All labeled Bothriechis nigroadspersus in Suppl. material 1.

Central American Eyelash-Pitviper

Bocaracá, toboba de pestañas, víbora de pestañas, oropel (yellow morph).

Bothriechis nigroadspersus is diagnosed based on the following combination of characters: (1) two raised and spinelike supraciliary scales; (2) anterior dorsal head scales keeled; (3) gular scales much smaller than chinshields; (4) 7–24 interoculolabials; (5) 2–6 canthals which may be nearly flat or with raised triangular projections; (6) loreal not in contact with preocular; (7) yellow morph present and common in some areas; (8) dorsal bands absent; (9) opposing kidney shaped dorsal marks present in the majority of individuals; (10) black speckles on dorsal scales usually absent; (11) black speckling on ventral surfaces usually absent or brown and faint; (12) ventral surfaces entirely white in some individuals; (13) iris pale straw yellow to golden with black reticulations or spots; (14) 21–25 dorsal scale rows at mid-body; (15) 153–169 ventrals in males, 148–167 in females; (16) maximum total length in males 626 mm, in females 916 mm.

Bothriechis nigroadspersus is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from all of them by having a higher number of ventral scales in both males and females (although there is overlap with some species), two raised and spinelike supraciliary scales (vs low and granular or broad and triangular in the other species), and by lacking dorsal bands. Instead, most individuals of B. nigroadspersus have either opposing kidney shaped reddish dorsal marks o are of the golden morph (=oropel) (Fig. 5). Bothriechis nigroadspersus differs from B. supraciliaris by having a higher number of ventral scales, no broad blotches or dorsal bands, and a different pattern on the dorsal aspect of the snout. Bothriechis nigroadspersus differs from B. torvus by having opposing kidney-shape dorsal marks, a higher number of ventrals, loreal not in contact with preocular, and comparatively smaller spines on the hemipenial body (Fig. 8).

Figure 8.

Hemipenial architecture of Bothriechis nigroadspersus in sulcate, lateral, and asulcate views. a. UTA R-32143 from Limón province, Costa Rica; b. UTA R-12957 from Aldea Vista Hermosa, Izabal department, Guatemala. Photos by Eric N. Smith.

An adult female, SVL 532 mm, tail length 96 mm (18.1% SVL); head length 34.4 mm (6.5% SVL) from tip of snout to angle of jaw; head width 28.5 mm (82.9% head length) taken at broadest point; rostral broader than high; nasal not entirely divided, but fused with first supralabial; loreal about 1/2 size of pit, in contact with nasal, canthals, 1 suprafoveal, 2 prefoveals, prelacunal, and supralacunal; prefoveals 4; subfoveals 3/3; postfoveals 0; prelacunal fused with second supralabial; sublacunals 1/1; supralacunal elongated and in contact with orbit; preoculars 1/1 (2/2 if supralacunal is considered a preocular); suboculars 1; postoculars 2; loreal pit large, directed anteriorly, located slightly below line drawn from center of eye to naris; supralabials 9 (including lacunolabial); infralabials 12, first pair meet posteriorly; mental broader than long; 1 pair of chin shields; 5 pairs of gulars between chin shields and preventrals; preventrals 3; anterior internasals 3; canthals 3/3; 2/2 moderately triangular but low supraciliary scales; supraoculars kidney-shaped, 2.2× longer than wide; intersupraoculars 5; anterior dorsal head scales keeled; posterior head scales keeled; dorsal scale rows at mid-body 23; ventrals 160; cloacal plate entire; 55 undivided subcaudals; tail prehensile.

(n = 2, Fig. 8) Everted and inflated, the organ is deeply bilobed, unicalyculate and slightly capitate; hemipenial lobes thick and cylindrical; in sulcate and asulcate views, lobe crotch ornamented with scattered spinules; sulcus spermaticus centrolineal, bifurcate and with walls weakly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal one third of each hemipenal lobe ornamented with calyces with spinulate edges. In sulcate view, hemipenial body surface nude, but with a pair of enlarged and strongly calcified lateral spines (basal hooks), one on each side; each hemipenial lobe ornamented with 1–3 mesial spines and 5–7 lateral spines, all about a third of the size of the basal hooks; the spines in each lobe are replaced distally by calyces with spinulate edges. In lateral view, hemipenial body nude with the exception of two basal spines; lobes also largely nude but with 5–6 smaller spines that are replaced distally by calyces. In asulcate view, the hemipenial body is nude with the exception of the pair of large lateral spines and also a pair of smaller mesial spines; hemipenial lobes largely nude but ornamented with smaller spines that decrease in size towards the lobe crotch.

Bothriechis nigroadspersus is an arboreal snake that inhabits evergreen lowland/foothill forests, plantations, and rural gardens. In Panama (Sorrell 2007, 2009) and Costa Rica (Solórzano 2004) these vipers were found to be mostly active at night or at dusk and on the base of tree or on low shrubby vegetation, and Leenders (2019) and Witold Lapinski (pers. comm. to AA) reports that they have been found in the canopy at heights of 32–35 m in Costa Rica. Sorrell (2007, 2009) observed that some snakes reside in the same perch for up to 14 days, 70.2% of individuals relocated each night, and only 6.4% remained at the same daytime perch site for more than two days. According to Rand and Myers (1990), Seifert (1983), Savage (2002), and our own observations, B. nigroadspersus is primarily nocturnal. During the day, most individuals of B. nigroadspersus remain in hunting posture on or close to their night perches, but others hide inside bromeliads, or occasionally remain active and move at ground level or on vegetation. Sorrell (2009) showed that members of this species are primarily ambush predators, but they also forage actively in search for food. In a study by Antonio (1980), captive juveniles fed mostly on frogs and attracted them by means of moving their bright yellow tails as a lure. Campbell and Lamar (2004), Sorrell (2009), Barrio-Amorós (2015), Morgan and Barrio-Amorós (2015), and Entiauspe-Neto et al. (2021) provide details on the dietary preference of adults encountered in the wild. These authors found that this age category also feeds on frogs (primarily treefrogs and rainfrogs), but also on lizards (anoles, whiptails, and geckos), birds (including hummingbirds), and mammals (bats, mice, and mouse opossums). We report on additional specimens found feeding on bats: CH 5651 from Coclé, Panama is preserved with an Artibeus jamaicensis in its mouth. An uncollected specimen photographed by Philipp Hoenle in Chiapas, Mexico was feeding on an unidentified bat, as well as it was another uncollected individual found by Barrio-Amorós near Arenal, Costa Rica, on the ground on a dirt road feeding on a bat, with only one wing out of its mouth. Gerhardt et al. (1993), Laurencio (2005), and Chavarría and Barrio-Amorós (2014) provide accounts of predation on this viper by hawks (Buteogallus urubitinga and Herpetotheres cachinnans) and snakes (Clelia clelia). Solórzano (2004) suggests that in Costa Rica, breeding in Bothriechis nigroadspersus coincides with the rainy season. Blody (1983) observed that females become sexually mature at an age of less than three years and can produce more than one litter per year. Antonio (1980) described the courtship and copulatory behavior of captive B. nigroadspersus from Honduras and Gómez et al. (2015) recorded a case of a female from Costa Rica that produced a litter after presumably storing sperm for no less than ~35 months (slightly under three years). A specimen from Lago Yojoa, Honduras, kept at Centro El Ocotal, produced a litter of four eggs and one live young after being kept in a terrarium without a male for 18 years (Alejandro Velasquez pers. comm. to AB). Antonio (1980), Blody (1983), Gómez et al. (2015), and Murphy and Mitchell (1984) report a gestation period of 150–166 days (~5 months) and litters of 6–23 neonates that measure 16–22.5 cm in total length at birth. Campbell and Lamar (2004) report that captive B. nigroadspersus have lived up to 20 years.

In a series of 477 snakebite cases in Costa Rica in 1979, 18.9% were caused by Bothriechis nigroadspersus (Bolaños 1984). Mekbel and Céspedes (1963) report that four of a series of 27 autopsied snakebite cases in San José were caused by this species. Savage (2002) observed that between 90 and 100 bites by B. nigroadspersus are reported in Costa Rica in a typical year, with 3–6 resulting in deaths according to Seifert (1983). An average bite results in the injection of ~0.5 cc of venom. The venom is hemotoxic and strongly myonecrotic when compared to other Central American vipers (Gutiérrez and Chaves 1980). In humans, it causes intense localized pain, progressive hemorrhagic edema, and, in some cases, hemorrhagic blisters or hives, ecchymoses, and necrosis (Lomonte et al. 2008; Pla et al. 2017). Prezotto-Neto et al. (2016) studied the composition of the venom of specimens of B. nigroadspersus from Costa Rica and found that its properties differ drastically from specimens of Bothriechis torvus from Vegachi, Antioquia. When compared to the latter, the venom of B. nigroadspersus was found to be more edematous, hemorrhagic, and lethal. LD50 estimated as 1.7–5.6 mg/kg in B. nigroadspersus vs 9.24 mg/kg in B. torvus (Bolaños 1972; Gutiérrez and Chaves 1980; Lomonte et al. 2008, 2012; Prezotto-Neto et al. 2016).

Bothriechis nigroadspersus is known from at least 335 localities (listed in Suppl. material 3) throughout much of the Mesoamerican biome, from the isthmus of Tehuantepec in Mexico to extreme northwestern Colombia (Cerro Tacarcuna) along the Panamanian border. The species occurs over an estimated 352,139 km² area and has been recorded at elevations 0–1,434 m above sea level (Fig. 3). Approximately 1.0% of the predicted area of distribution of B. nigroadspersus overlaps with that of B. supraciliaris. Although sympatry has not been reported, we bring attention to a photographic record of an individual of B. nigroadspersus from the vicinity of San Pedro, Puntarenas province, just 4 km away from a record of B. supraciliaris (Photo by Ethyn Maki on iNaturalist; Suppl. material 3). An estimated 1.0% of the predicted area of distribution of B. nigroadspersus overlaps with that of B. torvus, and we found evidence of sympatry between the two species in Cordillera de Pirré, Darién province, Panama. MHCH 1664 is a B. nigroadspersus and MVUP 1384 is a B. torvus; both from the same mountain range.

The specific epithet nigroadspersus comes from the Latin words nigrum (meaning “black”) and adspersus (meaning “sprinkled”). It refers to the minute black specks scattered throughout the dorsum of the holotype (Fig. 4).

We consider Bothriechis nigroadspersus to be included in the Least Concern category following IUCN Red List criteria (IUCN 2012) because the species is widely distributed (but see Discussion), present in dozens of protected areas, tolerates moderate habitat degradation, and is presumably not declining fast enough to qualify in a threatened category. In a rainforest locality in Panama, the occurrence rates of B. nigroadspersus have increased by a factor of ten in the period from 2006 to 2012 (Zipkin et al. 2020). In another locality in Panama, the species was found to be extremely common in forest islands within a matrix of pastures (Sorrell 2007). However, it is unsure whether such “forest islands” will sustain the species without the presence of a dense population nearby that may act as a source of individuals that can immigrate to the fragmented habitat (Sorrell 2007).

all labeled Bothriechis supraciliaris in Suppl. material 1.

Blotched Eyelash-Pitviper.

Bocaracá manchada.

Bothriechis supraciliaris is diagnosed based on the following combination of characters: (1) two or three raised and spinelike supraciliary scales; (2) anterior dorsal head scales smooth or barely keeled; (3) gular scales much smaller than chinshields; (4) 7–24 interoculolabials; (5) 4–5 canthals, most of which have raised triangular projections; (6) loreal in contact with preocular; (7) oropel morph extremely rare and with noticeably dark dorsal blotches on a yellowish background, rather than uniform golden-yellow; (8) reddish-brown irregular oval blotches or bands on dorsum; (9) opposing kidney shaped dorsal marks absent; (10) black speckles on dorsal scales absent; (11) black speckling on ventral surfaces usually absent or faint; (12) ventral surfaces not entirely white but yellowish anteriorly and light bluish-green posteriorly; (13) iris straw yellow with fine black speckles; (14) 21–23 dorsal scale rows at mid-body; (15) 144–150 ventrals in males, 139–148 in females; (16) maximum total length in males 382 mm, in females 583 mm.

Bothriechis supraciliaris occurs near and is most similar to B. nigroadspersus. It can be identified from this other much more variable and widely distributed viper species primarily by having fewer ventral scales (Table 2), loreal in contact with preocular, anterior head scales smooth or barely keeled (vs keeled in B. nigroadspersus), and by having reddish dorsal blotches or bands (Fig. 10). Lotzkat (2014) accurately pointed out that the two species differ in the dorsal pattern of the snout in contrastingly marked specimens. In B. supraciliaris there is a single anteriormost dorsal blotch centrally on the snout (Figs 9a, 10b–e); in B. nigroadspersus, there are two paramedian blotches that may touch each other or be fused to form a short transverse band, but nevertheless remain discernible. Lotzkat (2014) also brings attention to the fact that specimens of B. supraciliaris have very little or no dark pigmentation on the ventral surfaces at least anteriorly in adult specimens (vs. extensive dark pigmentation throughout the venter which are not of the oropel morph in B. nigroadspersus).

Figure 9.

Adult female holotype of Bothriechis supraciliaris KU 31997 in a. Dorsal and b. Ventral view. Photos by Hannah Som.

Figure 10.

Photographs of some specimens of Bothriechis supraciliaris in life. a, d, e. From Reptilandia, Costa Rica; and b, c. From a private collection in Costa Rica. Photos by Jose Vieira.

(n = 2, Fig. 11) Everted and inflated, the organ is deeply bilobed, calyculate and semicapitate; hemipenial lobes cylindrical and with minimal separation between them; in sulcate and asulcate views, lobe crotch ornamented with densely packed spinules; sulcus spermaticus centrolineal, bifurcate and with walls weakly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal one third of each hemipenal lobe densely ornamented by calyces with strongly defined spinulate edges. In sulcate view, hemipenial body surface nude medially, but with enlarged and strongly calcified lateral spines followed by 1–2 rows of smaller obliquely-arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with 1–2 mesial spines and 3–4 lateral spines, all about half the size of the larger lateral spines at the base of the hemipenial body; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes with rows of spines, but otherwise smooth; distal 1/4 strongly calyculate. In asulcate view, the center of hemipenial body is nude except for a pair of large lateral spines; hemipenial lobes ornamented with 3–4 rows of smaller spines that decrease in size towards the lobe crotch.

Figure 11.

Hemipenial architecture of Bothriechis supraciliaris in sulcate, lateral, and asulcate views. a. UTA R-35246 from Jardin Botánico Las Cruces, Puntarenas province, Costa Rica; b. UTA R-35192 from Jardin Botánico Las Cruces, Puntarenas province, Costa Rica. Photos by Eric N. Smith.

Bothriechis supraciliaris is an arboreal snake that inhabits evergreen lower-montane forests, cloud forests, clearings with coffee and banana plantations, edges of farm fields, and rural gardens (Campbell and Lamar 2004; Lotzkat 2014; Leenders 2019; Solórzano et al. 2021). Solórzano et al. (1998) and Solórzano (2004) report that individuals of B. supraciliaris are crepuscular, nocturnal, and tend to spend more time on the ground than other Bothriechis: they found 22 out of 25 individuals on the forest floor. However, all individuals seen by CLBA (n=10) were on bushes from 30 cm to 2 m above the ground. Another naturalist, Norberto Solano, with more than 80 sighting of the species, only found one on the ground (Norberto Solano, pers. comm. to CLBA). During the day, individuals have been found resting on the ground or at the base of trees and shrubs (Solórzano 2004). Lotzkat (2014) and Batista et al. (2020) found individuals on low understory vegetation 0.5–2 m above the ground, either in ambush posture, crawling, or hanging from the tail. These authors also report that SMF 89764 was in the process of swallowing a comparatively large Craugastor fitzingeri. Solórzano et al. (1998) found mostly small forest-floor rodents in the stomach contents of four dissected specimens. They also report that specimens found in resting positions were curled in a loose circle and mostly on horizontal, wide surfaces.

Lomonte et al. (2012) studied the venom of this species in Costa Rica and found that it has a potent hemorrhagic action, moderate myotoxicity, and very weak procoagulant activity. These authors estimated its lethal activity at LD50 6.04 mg/kg and found that the equine polyvalent (Viperidae) antivenom from Instituto Clodomiro Picado was able to neutralize the lethal effect of B. supraciliaris venom. The antivenom tested was produced from the plasma of equines immunized with a mixture of the venoms of Bothrops asper, Crotalus simus, and Lachesis stenophrys (Lomonte et al. 2012).

Bothriechis supraciliaris is known from at least 24 localities (listed in Suppl. material 3) along the Pacific slopes of the Cordillera de Talamanca in southwestern Costa Rica and western Panama. The species occurs over an area of approximately 3,568 km² and has been recorded at elevations 734–1,506 m above sea level (Fig. 3). We found that 100% of the predicted area of distribution of B. supraciliaris is included in the predicted area of distribution of B. nigroadspersus.

The specific epithet supraciliaris, which comes from the Latin words supra (meaning “above”) and cilium (meaning “eyelash”), refers to the prominent spinelike scales above the eye.

We consider Bothriechis supraciliaris to be included in the Endangered category (instead of Least Concern; see Solórzano et al. 2021) following the IUCN criteria B1a, b (i, iii, iv) (IUCN 2012), because the species’ extent of occurrence is estimated to be less than 5,000 km² (Fig. 3) and its habitat is severely fragmented and declining in extent and quality due to deforestation. Although B. supraciliaris occurs in three protected areas (Estación Biológica Las Cruces, Las Nubes Biological Reserve, and Parque Binacional La Amistad), the remaining localities where the species has been recorded (Suppl. material 3) are in forest patches surrounded by a matrix of pastures and small settlements. Based on the species distribution model presented in Fig. 3 in combination with maps of vegetation cover of Central America (CATHALAC 2011), we estimate that nearly 37% of the forest cover throughout the species’ potential distribution area has been destroyed, mostly due to the expansion of the agricultural frontier.

All labeled Bothriechis schlegelii in Suppl. material 1.

Highland Eyelash-Pitviper, Schlegel’s Eyelash-Pitviper.

Víbora de tierra fría, víbora de pestañas de Schlegel, guaruma.

Bothriechis schlegelii is diagnosed based on the following combination of characters: (1) two or three triangular and moderately raised supraciliary scales; (2) anterior dorsal head scales smooth; (3) gular scales much smaller than or similar in size to chinshields; (4) 3–11 interoculolabials; (5) 1–3 canthals which may be flat or slightly raised forming a ridge along the canthus; (6) loreal in contact with preocular in ~1/3 of specimens; (7) yellow morph absent; (8) dorsal bands black or dark brown; (9) no opposing kidney shaped dorsal marks; (10) black speckles on dorsal scales usually absent; (11) black speckling on ventral surfaces usually absent; (12) ventral surfaces never entirely white; (13) iris pale orange, light green, or golden yellow usually without speckles; (14) 21–25 dorsal scale rows at mid-body; (15) 139–156 ventrals in males, 135–153 in females; (16) maximum total length in males 834 mm, in females 969 mm.

Bothriechis schlegelii sensu stricto is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from the other species except B. klebbai sp. nov. and B. khwargi sp. nov. in having two triangular and moderately raised supraciliary scales (supraciliaries either low and granular or enlarged and spinelike in the other species). Bothriechis schlegelii occurs near the distribution of B. torvus (Fig. 3), from which it differs by having anterior dorsal head scales smooth, 1–3 canthals (rather than 3–8), bands black or dark brown (rather than pink or red), ventral surfaces never entirely white, a lower number of ventrals in both males and females, and larger basal hooks on the hemipenial body (Fig. 14). Bothriechis schlegelii is most similar to B. klebbai sp. nov. and B. rasikusumorum sp. nov., but these other species occur parapatrically and are characterized by having small supraciliary scales, dorsal and ventral surfaces heavily speckled with black, gular scales similar in size or larger than chinshields, and no enlarged basal hooks on the hemipenial body. Bothriechis schlegelii differs from B. khwargi sp. nov. by having smooth anterior dorsal head scales (instead of keeled), a lower number of canthals, no reddish bands, and an entirely pale white belly.

Figure 12.

Photographs of some specimens of Bothriechis schlegelii from Antioquia department, Colombia, in life. a, c, f. From the live collection at INSV-SR, Serpentario Nacional de Colombia; b, d, e, g. from the live collection at SUA, Serpentario de la Universidad de Antioquia. Photos by Jose Vieira.

Figure 13.

Photographs of some specimens of Bothriechis schlegelii in life. a. Adult from Planes de San Rafael, Risaralda department, Colombia; b–f. Adults from Popayán, Cauca department, Colombia, photographed at the Serpentario de la Universidad del Cauca. Photos by Jose Vieira and Amanda Quezada.

Figure 14.

Hemipenial architecture of Bothriechis schlegelii in sulcate, lateral, and asulcate views. a. IAVH-R 6055 from Reserva Tesorito, Valle del Cauca department, Colombia; b. IAVH-R 6598 from Popayán, Cauca department, Colombia; c. IAVH-R 5465 from Fresno, Tolima department, Colombia. Photos by Duván Zambrano.

(n = 7; three depicted in Fig. 14) Everted and inflated, the organ is deeply bilobed, calyculate and noncapitate; hemipenial lobes uniformly cylindrical or tapering towards the tip; in sulcate and asulcate views, lobe crotch ornamented with densely packed spines that become larger distally; sulcus spermaticus centrolineal, bifurcate and with walls strongly defined (weakly in IAVH-R 5465 and ICN PR 13225), bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal one third to one half of each hemipenal lobe densely ornamented with small calyces with strongly defined spinulate edges. In sulcate view, hemipenial body surface with small spinules medially, but with enlarged and strongly calcified lateral spines (basal hooks) followed by 2–4 rows of much smaller obliquely-arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with mesial and lateral spines about 1/3–1/10 the size of the large basal hooks; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes with rows of spines, but otherwise non-spiculate; distal 1/3–1/2 of lobes strongly calyculate. In asulcate view, the center of hemipenial body is nude to barely spiculate; hemipenial lobes ornamented with 3 rows of smaller spines that decrease in size towards the lobe crotch.

A juvenile, SVL 183 mm, tail length 35.3 mm (19.3% SVL; tail-tip missing); head length 12.8 mm (7.0% SVL) from tip of snout to angle of jaw; head width 10.3 mm (80.5% head length) taken at broadest point; rostral broader than high (2.6 × 1.9 mm); nasal divided and not fused with first supralabial; loreal about 1/3 size of pit, in contact with preocular, postnasal, second canthal, 1 suprafoveal, 1 prefoveal, prelacunal, and supralacunal; prefoveals 3/4; subfoveals 2/2; postfoveals 0; prelacunal fused with second supralabial; sublacunals 2/2; supralacunal L-shaped and in contact with orbit; preoculars 1/1 (2/2 if supralacunal is considered a preocular); suboculars 1/1; postoculars 2/2; loreal pit large, directed anteriorly, located slightly below line drawn from center of eye to naris; supralabials 8/8 (including lacunolabial); infralabials 10/10, first pair meet posteriorly; mental broader than long (2.7 × 1.5 mm); 1 pair of chinshields; 3 pairs of gulars between chinshields and preventrals; preventrals 3; anterior internasals 3; canthals 2/2; 3/3 moderately triangular but low supraciliary scales; supraoculars oblong, 2.5× longer than wide; intersupraoculars 5; anterior dorsal head scales smooth; posterior head scales keeled; interrictals 25; dorsal scale rows 21/21/17; ventrals 150; cloacal plate entire; 50 undivided subcaudals; tail prehensile.

Bothriechis schlegelii is an arboreal snake that inhabits evergreen montane forests, planted forests, coffee plantations, and urban/rural gardens. Based on our own field notes, iNaturalist records, and the literature (Rojas-Morales 2012; Galofre-Ruiz 2016), vipers of this species are found at night perched on low (less than 3 m above the ground) shrubby vegetation or at ground level during the day, either in ambush posture or moving. Most observations are of snakes active on rocks, leaf-litter, grass, and even crossing roads during daylight hours. Santiago Ayerbe (pers. comm. to AA) reports that in Cauca, individuals of this species prey upon lizards (anolines and Pholidobolus), rodents, and hummingbirds. Rojas-Morales (2012) reports that “though generally docile, individuals of B. schlegelii defend themselves with frontal displays and striking.”

Galofre-Ruiz (2016) reports two cases of human envenomation by this snake species in departments Caldas and Tolima. The victims developed pain at the site of the wound, paresthesia, and edema, but recovered with the use of polyvalent antivenom. Sevilla-Sánchez et al. (2021) report that most accidents caused by this snake involve coffee plantation workers bitten on the hands or face during the harvesting work. In a series of 1,653 cases of envenomation in Cauca province between 2009 and 2018, 8.4% were caused by B. schlegelii (Sevilla-Sánchez et al. 2021), whereas 5.5% of 218 cases in departments Antioquia and Chocó between 1989 and 1990 were caused by a combination of B. schlegelii and B. torvus (Otero et al. 1992a). Of these, one envenomation was moderate, 11 were mild, and none involved systemic complications. The venom in this Antioquian-Chocoan mixed Bothriechis sample was found to be the least edematous, hemorrhagic, and lethal (LD50 estimated as 10.3 mg/kg) among a sample of eight Colombian venomous snakes (Otero et al. 1992b). Ayerbe et al. (1979) provided a report of a coffee plantation worker that died after being bitten on the tongue.

Bothriechis schlegelii is endemic to Colombia. It is known from at least 161 localities (listed in Suppl. material 3) on Colombia’s Cordillera Central and Occidental, from Cauca department in the south to Antioquia department in the north. The species occurs over an area of approximately 40,432 km² and has been recorded at elevations 1,034–2,597 m above sea level (Fig. 3). Approximately 8.8% of the predicted area of distribution of B. schlegelii overlaps with that of B. torvus, but we did not find evidence of sympatry. In Valle del Cauca department, we found the two species separated by an airline distance of about 10 km.

The specific epithet schlegelii honors Hermann Schlegel (1804–1884), a renowned German ornithologist and herpetologist.

We consider Bothriechis schlegelii to be included in the Near Threatened category following IUCN Red List criteria (IUCN 2012) primarily because the species’ extent of occurrence is estimated to be much larger than the 20,000 km² needed to meet B1 criteria for the Vulnerable category. However, although the species occurs in numerous protected areas (no less than 13; see Suppl. material 2), the majority of the species’ montane forest habitat has been destroyed. Based on the distribution model presented in Fig. 3 in combination with maps of vegetation cover of Colombia (IDEAM 2014), we estimate that only ~23% of the species’ forest habitat is still standing.

All labeled Bothriechis torvus in Suppl. material 1.

Birri Eyelash­-Pitviper.

Víbora birrí, serpiente guinda, pestañona.

Bothriechis torvus is diagnosed based on the following combination of characters: (1) 3 raised supraciliary scales, triangular, but rounded and not spinelike; (2) anterior dorsal head scales keeled; (3) gular scales much smaller than chinshields; (4) 6–18 interoculolabials; (5) 3–8 canthals, most of them with raised triangular projections; (6) loreal in contact with preocular in some populations; (7) yellow morph absent; (8) dorsal bands pink or red; (9) no opposing kidney shaped dorsal marks; (10) black speckles on dorsal scales absent; (11) black speckling on ventral surfaces absent or faint; (12) ventral surfaces entirely white in some individuals; (13) iris pale bluish-green or straw yellow with fine black speckling; (14) 21–23 dorsal scale rows at mid-body; (15) 148–159 ventrals in males, 141–153 in females; (16) maximum total length in males 378 mm, in females 657 mm.

Bothriechis torvus is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from all of them by having three raised and triangular supraciliary scales, anterior dorsal head scales keeled, a high number of canthals (3–8) and interoculolabials (6–18), thin pink dorsal bands, and entirely pale white belly. Bothriechis torvus differs from B. schlegelii sensu stricto by having anterior dorsal head scales keeled, 3–8 canthals (rather than 1–3), bands pink or red (rather than black or dark brown; Fig. 15), ventral surfaces entirely white, a higher number of ventrals in both males and females, smaller body size, and smaller basal hooks on the hemipenial body (Fig. 16). Bothriechis torvus is sympatric with B. nigroadspersus along the Serranía de Pirre, Darién province, Panama (lime green shade in Fig. 3). The two species differ in coloration (Figs 5, 15). Bothriechis torvus has dorsal bands (vs opposing kidney shaped marks), three broad and triangular enlarged supraciliary scales (vs two thin and spinelike), a lower number of ventral scales, and lateral surface of the hemipenial body and lobes more heavily packed with larger spines (Fig. 16). Bothriechis torvus resembles B. rahimi sp. nov., but this other species occurs south of the known distribution of B. torvus and is characterized by having a lower number of ventrals, enlarged spinelike supraciliary scales, faint dorsal banding, and presence of the yellow morph. Bothriechis torvus differs from B. khwargi sp. nov. by having pink bands (bands absent or dark vertebral blotches in B. khwargi sp. nov.).

Figure 15.

Photographs of some specimens of Bothriechis torvus in life. a. Adult and b. Juvenile (same individual) from Morromico Reserve, Chocó department, Colombia; c. TH 145 adult female from Morromico Reserve, Chocó department, Colombia; d. Adult and e. Juvenile from Urabá, Antioquia department, Colombia. Photos by Jose Vieira.

Figure 16.

Hemipenial architecture of Bothriechis torvus in sulcate, lateral, and asulcate views. ICN 0421 from Valle del Cauca department, Colombia. Photos by Duván Zambrano.

(n = 1; Fig. 16) Everted and inflated, the organ is deeply bilobed, calyculate and noncapitate; hemipenial lobes cylindrical, but tapering towards the capitulum; in sulcate and asulcate views, lobe crotch ornamented with densely packed spines that become larger distally; sulcus spermaticus centrolineal, bifurcate and with walls strongly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal half of each hemipenal lobe densely ornamented with small calyces with defined spinulate edges. In sulcate view, hemipenial body surface spinulate medially with enlarged and strongly calcified lateral basal hooks followed by rows of smaller obliquely arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with mesial and lateral spines about 1/5 the size of the large basal hooks; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes non-spiculate but with rows of spines; distal half of lobes strongly calyculate. In asulcate view, the center of hemipenial body is nude to barely spiculate; hemipenial lobes ornamented with 2 rows of smaller spines (about 1/3 the size of the lateral basal hooks) that decrease in size towards the lobe crotch.

Bothriechis torvus is an arboreal snake that inhabits evergreen lowland/foothill forests. We have found vipers of this species active at night crawling on ferns, tree branches, and trunks from 1.8 to 5 m above the ground or during the day perched on arboreal vegetation up to 3.5 m above the ground. Specimens from Cerro Sapo and Pirre Mountain ranges, eastern Panama, were found in a cloud forest consisting predominantly of trees covered with moss and a large variety of understory and midstory bromeliads. In captivity, TH 145 (Fig. 15c) and another specimen from Morromico, Chocó department, Colombia, consumed lizards (Anolis and Lepidodactylus) and frogs (Craugastor and Pristimantis).

Prezotto-Neto et al. (2016) studied the composition of the venom of specimens of Bothriechis torvus from Vegachi, Antioquia, and found that its properties differ drastically from specimens of B. nigroadspersus from Costa Rica. When compared to the latter, the venom of B. torvus was found to be less edematous, hemorrhagic, and lethal (LD50 estimated as 9.24 mg/kg vs 5.60 mg/kg).

Bothriechis torvus is known from at least 37 localities (listed in Suppl. material 3) along the Chocó and Río Magdalena valley regions of northern Colombia and extreme southeastern Panama. The species occurs over an area of approximately 61,466 km² and has been recorded at elevations 61–1,413 m above sea level (Fig. 3). The ENM suggests the distribution is not continuous across the valley of the Río Atrato (see Discussion).

The specific epithet torvus is a Latin word meaning “fierce.” It refers to the protruding supraciliary scales, which according to Andrés Posada Arango, give this species an “air féroce.”

We consider Bothriechis torvus to be included in the Least Concern category following IUCN Red List criteria (IUCN 2012) because the species is distributed over a region that holds large areas of continuous unspoiled forest. Based on the species distribution model presented in Fig. 3 in combination with maps of vegetation cover of Colombia (IDEAM 2014) and Panama (CATHALAC 2011), we estimate that more than half (~59%) of the species’ forest habitat is still standing. Unfortunately, vast areas of the Chocó rainforest in northern Colombia and towards central Panama have already been converted to pastures (Myers et al. 2000). However, B. torvus occurs over an area greater than 50,000 km² and is presumably not declining fast enough to qualify for a threatened category.

Holotype : UIS-R 4294 (Figs 17, 18b), adult female collected by Elson Meneses-Pelayo on November 15, 2017 at Finca la Esperanza, vereda Sogamoso, municipio de Betulia, Santander department, Colombia (7.00600, -73.421608; 1195 m).

Paratypes : All labeled Bothriechis khwargi sp. nov. in Suppl. material 1.

Khwarg’s Eyelash-Pitviper.

Víbora de pestañas de Khwarg.

Bothriechis khwargi sp. nov. is diagnosed based on the following combination of characters: (1) two triangular and moderately raised supraciliary scales; (2) anterior dorsal head scales keeled; (3) gular scales much smaller than chinshields; (4) 7–14 interoculolabials; (5) 3–4 canthals, some of which with raised triangular projections; (6) loreal in contact with preocular in ~1/3 of specimens; (7) yellow morph absent; (8) dorsal bands absent, faint, or restricted to top of dorsum in juveniles; (9) opposing kidney shaped dorsal marks absent; (10) black speckles on dorsal scales absent; (11) black speckling on ventral surfaces absent; (12) ventral surfaces entirely white in most individuals; (13) iris pale green or straw yellow; (14) 21–23 dorsal scale rows at mid-body; (15) 144–153 ventrals in males, 145–154 in females; (16) maximum total length in males 219 mm, in females 610 mm.

Bothriechis khwargi sp. nov. is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from all of them by having two triangular and moderately raised supraciliary scales, anterior head scales keeled, gular scales much smaller than chinshields, entirely pale white belly in most individuals, and dorsal bands faint or absent. Bothriechis khwargi sp. nov. resembles B. torvus, but this other species does not occur along the slopes of the Cordillera Oriental and is characterized by having thin pink bands on the dorsum (Fig. 15). Bothriechis khwargi sp. nov. occurs in sympatry with B. klebbai sp. nov. along the upper slopes of the Serranía De Los Yariguíes, but it differs from this other species by being smaller in body size, having an entirely white belly, pale greenish iris, keeled anterior dorsal head scales, gulars much smaller than chinshields, and by lacking black speckling on dorsal and ventral surfaces (Fig. 18).

Figure 17.

Female holotype of Bothriechis khwargi sp. nov. UIS-R 4294 in a. Dorsal and b. Ventral view. Photos by Johan Cordón-Rangel.

Figure 18.

Photographs of some specimens of Bothriechis khwargi sp. nov. in life. a. UIS-R-4921 female from Quebrada La Boquerona, vereda La Putana, municipio de Betulia, Santander department b. UIS-R 4294 female holotype from Finca La Esperanza, vereda Sogamoso, municipio de Betulia, Santander department, Colombia. Photos by Jose Vieira and Elson Meneses Pelayo.

An adult female, SVL 511 mm, tail length 99 mm (19.4% SVL); head length 31.7 mm (6.2% SVL) from tip of snout to angle of jaw; head width 21.8 mm (68.8% head length) taken at broadest point; rostral broader than high (3.0 × 2.6 mm); nasal divided and not fused with first supralabial; loreal about same size of pit, contacting postnasal, 1 canthal, 1 prefoveal, supralacunal, lacunolabial, and preocular; prefoveals 4/4; subfoveals 3/3; postfoveals 0; prelacunal fused with second supralabial; sublacunals 1/1; supralacunal elongated and barely reaches orbit; preoculars 1/1 (2/2 if supralacunal is considered a preocular); suboculars 1/1; postoculars 1/1; loreal pit large, directed anteriorly, located slightly below line drawn from center of eye to naris; supralabials 9/8 (including lacunolabial); infralabials 11/12, first pair meet posteriorly; mental broader than long (4.0 × 1.4 mm); 1 pair of chinshields; 5 pairs of gulars between chinshields and preventrals; preventrals 2; anterior internasals 2; canthals 3/3; supraciliary scales low and granular with the exception of a pair of low, but triangular and pointed scales; supraoculars bean-shaped, 2.3× longer than wide; intersupraoculars 8; anterior dorsal head scales lightly keeled; posterior head scales strongly keeled; interrictals 25; dorsal scale rows 23/23/19; ventrals 154; cloacal plate entire; 54 undivided subcaudals; tail prehensile.

Bothriechis khwargi sp. nov. is an arboreal snake that inhabits evergreen foothill forests. Vipers of this species have been seen at night or during the day, either at ground level or on low understory vegetation. EMP and CLBA found one individual at 1 m above the ground in a fern foraging at night.

We know of no snakebites caused by this species in Colombia.

Bothriechis khwargi sp. nov. is known from at least 19 localities (listed in Suppl. material 3) along the western foothills of Colombia’s Cordillera Oriental. The species occurs over an area of approximately 14,697 km² and has been recorded at elevations 167–1,800 m above sea level (Fig. 3). Approximately 29% of the predicted area of distribution of B. khwargi sp. nov. overlaps with that of B. klebbai sp. nov., and we found evidence of sympatry between the two species at elevations above 1,700 m on the western slopes of the Serranía de los Yariguíes. UIS-R 4447 is a B. klebbai sp. nov. and was found just 3.7 km airline distance from a photographic record of an B. khwargi sp. nov.

This species is named in honor of Dr. Juewon Khwarg, in recognition of his support of the discovery and protection of new species of vipers in the Andes of Colombia. Khwarg is a conservationist with a special love for the lesser-known reptiles of the unexplored regions of the tropics.

We consider Bothriechis khwargi sp. nov. to be included in the Vulnerable category following the IUCN criteria B1a, b (i, iii, iv) (IUCN 2012), because the species’ extent of occurrence is estimated to be less than 20,000 km² (Fig. 3) and its habitat is severely fragmented and declining in extent and quality due to deforestation. Although B. khwargi sp. nov. occurs in one national park (Serranía de los Yariguíes) and a privately protected area (Reserva Natural Reinita Cielo Azul), most localities where the species has been recorded (Suppl. material 3) are in heavily human-modified areas. Based on the species distribution model presented in Fig. 3 in combination with maps of vegetation cover of Colombia (IDEAM 2014), we estimate that nearly 79% of the forest cover throughout the species’ potential distribution area has been destroyed, mostly due to the expansion of the agricultural frontier.

Holotype : ICN 2786 (Fig. 19), adult male collected by Pedro M. Ruiz-Carranza on September 21, 1979 at Vereda Virolín, municipio de Charalá, Santander department, Colombia (6.10720, -73.19781; 1819 m).

Paratypes : All labeled Bothriechis klebbai sp. nov. in Suppl. material 1.

Klebba’s Eyelash­-Pitviper.

Víbora de pestañas de Klebba.

Bothriechis klebbai sp. nov. is diagnosed based on the following combination of characters: (1) supraciliary scales low and granular or two raised, but not sharp; (2) anterior dorsal head scales smooth; (3) gular scales similar in size to chinshields; (4) 7–11 interoculolabials; (5) 2–4 canthals which may be flat or slightly raised forming a ridge along the canthus; (6) loreal in contact with preocular in ~1/3 of specimens; (7) yellow morph absent; (8) dorsal bands black; (9) opposing kidney shaped dorsal marks absent; (10) black speckles on dorsal scales present; (11) black speckling on ventral surfaces present, prominent; (12) ventral surfaces never entirely white; (13) iris rich dark reddish brown; (14) 21–23 dorsal scale rows at mid-body; (15) 144–151 ventrals in males, 141–151 in females; (16) maximum total length in males 671 mm, in females 874 mm.

Bothriechis klebbai sp. nov. is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from most of them by having supraciliaries low and granular or two raised but not sharp, a low number of canthals (2–4), gular scales similar in size to chinshields, and dorsal and ventral surfaces heavily speckled with black pigment. Bothriechis klebbai sp. nov. resembles B. rasikusumorum sp. nov., but this other species occurs on the southern portion of Colombia’s Cordillera Oriental and is characterized by having more than 151 ventrals in females, loreal not in contact with preocular, and by lacking paired oblong blotches on each side of the dorsum (a characteristic variably present in B. klebbai sp. nov.). Furthermore, Bothriechis klebbai sp. nov. lacks enlarged basal hooks on the hemipenial body (present in B. rasikusumorum sp. nov.). Bothriechis klebbai sp. nov. also resembles B. schlegelii, but this other species does not occur on the Cordillera Oriental and is characterized by having two triangular and moderately raised supraciliary scales, a different iris color (pale orange, light green, or golden yellow usually without speckles vs rich dark reddish brown), and by lacking black speckles on the dorsal and ventral scales in most populations (Figs 19, 20). Bothriechis klebbai sp. nov. occurs in sympatry with B. khwargi sp. nov. along the upper slopes of the Serranía De Los Yariguíes, but it differs from this other species by being larger in body size, having a dark green belly, smooth anterior dorsal head scales, gulars similar in size to or large than chinshields, and by having prominent black speckling on dorsal and ventral surfaces.

Figure 19.

Adult male holotype of Bothriechis klebbai sp. nov. ICN 2786 in a. Dorsal and b. Ventral view. Photos by Duván Zambrano.

Figure 20.

Photographs of some specimens of Bothriechis klebbai sp. nov. in life from Finca la Arrinconada, vereda Esparta, minicipio de Santa Bárbara, Santander department, Colombia. a. UIS-R 4139 adult male; b. INSV-SR-00098 adult of undetermined sex; and c. UIS-R-4296 juvenile male. Photos by Elson Meneses Pelayo and Jose Vieira.

(n = 3; Fig. 21) Everted and inflated, the organ is deeply bilobed, calyculate and noncapitate; hemipenial lobes cylindrical or spindle shaped; in sulcate and asulcate views, lobe crotch ornamented with densely packed small spines that become larger distally; sulcus spermaticus centrolineal, bifurcate and with walls weakly defined (strongly in ICN 2786), bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal half of each hemipenal lobe densely ornamented with small calyces with strongly defined spinulate edges. In sulcate view, hemipenial body surface spinulate medially; calcified spines at the base of the hemipenial body only slightly larger than adjacent rows of smaller obliquely arranged mesial spines that become gradually smaller towards each lobe’s capitulum (=no obvious basal hooks); each hemipenial lobe ornamented with mesial and lateral spines homogenous in size; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes with rows of spines, but otherwise non-spiculate; distal half strongly calyculate. In asulcate view, the center of hemipenial body is nude to barely spiculate; hemipenial lobes ornamented with 4 rows of spines that decrease in size towards the lobe crotch.

Figure 21.

Hemipenial architecture of Bothriechis klebbai sp. nov. in sulcate, lateral, and asulcate views. a. ICN 2786 and b. ICN 2855 from Virolín, municipio de Charalá, Santander department, Colombia; c. UIS-R 4803 from vereda Naranjal, municipio de Coromoro, Santander department, Colombia. Photos by Duván Zambrano and Elson Meneses Pelayo.

An adult male, SVL 349 mm, tail length 75 mm (21.5% SVL); head length 27.8 mm (8.0% SVL) from tip of snout to angle of jaw; head width 20.1 mm (72% head length) taken at broadest point; rostral broader than high (2.7 × 1.8 mm); nasal divided and not fused with first supralabial; loreal about 1/2 size of pit, contacting postnasal, 2 canthals, lacunolabial, supralacunal, and preocular; prefoveals 4/4; subfoveals 3/4; postfoveals 0; prelacunal fused with second supralabial; sublacunals 2/2 (one of which is small and granular); supralacunal elongated and in contact with orbit; preoculars 1/1 (2/2 if supralacunal is considered a preocular); suboculars 1/1; postoculars 1/1; loreal pit large, directed anteriorly, located slightly below line drawn from center of eye to naris; supralabials 8/8 (including lacunolabial); infralabials 11/11, first meet posteriorly; mental broader than long (3.3 × 3.0 mm); 1 pair of chinshields; 5 pairs of gulars between chinshields and preventrals; preventral 1; anterior internasals 2; canthals 3/3; supraciliary scales low and granular with the exception of one raised and triangular scale; supraoculars oblong, 1.8× longer than wide; intersupraoculars 6; anterior dorsal head scales smooth; posterior head scales barely keeled; interrictals 27; dorsal scale rows 21/21/18; ventrals 148; cloacal plate entire; 56 undivided subcaudals; tail prehensile.

Bothriechis klebbai sp. nov. is an arboreal snake that inhabits montane cloud forests. Vipers of this species have been seen at night or during the day, either at ground level or on low understory vegetation. In captivity, this species is known to hybridize with B. khwargi sp. nov. INSV-SR-1015 is believed to be a hybrid between the two species. We (JV and EMP) have seen this species preying upon Anolis heterodermus.

We know of no snakebites caused by this species in Colombia nor any studies on the venom that could be assigned to this species.

Bothriechis klebbai sp. nov. is known from at least 23 localities (listed in Suppl. material 3) along the western slopes of Colombia’s Cordillera Orien­tal. The species occurs over an estimated 20,061 km² and has been recorded at elevations 1,418–2,380 m above sea level (Fig. 3). Approximately 21% of the predicted area of distribution of B. klebbai sp. nov. overlaps with that of B. khwargi sp. nov.

Named after Casey Klebba, whose dedication to the preservation of tropical biodiversity is exemplary. As a co-founder of Minifund.org, alongside Carly Jones, he has been one of the most invaluable supporters of AA’s field expeditions to remote areas of Ecuador and Colombia, resulting in the discovery of many new species to science.

We consider Bothriechis klebbai sp. nov. to be included in the Near Threatened category following IUCN Red List criteria (IUCN 2012) primarily because the species’ extent of occurrence is estimated to be greater than the 20,000 km² needed to meet B1 criteria for the Vulnerable category. However, although the species occurs in at least two national parks (Serranía de los Yariguíes and Guanentá-alto Río Fonce), the majority of the species’ montane forest habitat has been destroyed. Based on the distribution model presented in Fig. 3 in combination with maps of vegetation cover of Colombia (IDEAM 2014), we estimate that only ~14% of the species’ forest habitat is still standing.

Holotype : CZUT-R 349 (Fig. 22), adult male collected by Hugo Hernández at Vereda El Regenero, Huila department, Colombia (1.82023, -75.99867; 1616 m).

Paratypes : All labeled Bothriechis rasikusumorum sp. nov. in Suppl. material 1.

Shah’s Eyelash-Pitviper.

Víbora de pestañas de los Shah.

Culebra de tiro.

Bothriechis rasikusumorum sp. nov. is diagnosed based on the following combination of characters: (1) supraciliary scales low and granular, or two pointy but not raised; (2) anterior dorsal head scales smooth; (3) gular scales similar in size to chinshields; (4) 5–10 interoculolabials; (5) 2–3 canthals which may be flat or slightly raised forming a ridge along the canthus; (6) loreal not in contact with preocular; (7) yellow morph absent; (8) dorsal bands dark brown or black; (9) opposing kidney shaped dorsal marks absent; (10) black speckles on dorsal scales present; (11) black speckling on ventral surfaces prominent posteriorly; (12) ventral surfaces never entirely white; (13) iris light green, yellow, or reddish brown with black reticulations; (14) 21–23 dorsal scale rows at mid-body; (15) 144–152 ventrals in males, 152–153 in females; (16) maximum total length in males 650 mm, in females 799 mm.

Bothriechis rasikusumorum sp. nov. is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from most of them by having supraciliaries not raised, a low number of canthals (2–3), a low number of ventral scales, and dorsal and ventral surfaces heavily speckled with black pigment (Figs 22, 23a). Bothriechis rasikusumorum sp. nov. resembles B. klebbai sp. nov., but this other species occurs on the northern portion of Colombia’s Cordillera Oriental and is characterized by having less than 152 ventrals in females, a rich reddish-brown iris, a series of paired oblong blotches on each side of the dorsum, and no basal hooks on the hemipenial body (Fig. 21). Bothriechis rasikusumorum sp. nov. is also similar to B. schlegelii, but this other species occurs northwest of the known distribution of B. rasikusumorum sp. nov. and is characterized by lacking black speckles on the dorsal and ventral scales in most populations (Figs 12, 13), having two triangular and moderately raised supraciliary scales, and basal hooks that are 3–10X the size of adjacent spines at the base of the hemipenial body (Fig. 14).

Figure 22.

Adult male holotype of Bothriechis rasikusumorum sp. nov. CZUT-R 349 in a. Dorsal and b. Ventral view. Photos by Duván Zambrano.

Figure 23.

Photographs of living specimens of Bothriechis rasikusumorum sp. nov. from Huila department, Colombia. a. La Umbría; b. SUA 4659 Finca Miraflores. Photos by Jose Vieira and Duván Zambrano.

(n = 1; Fig. 24) Everted and inflated, the organ is deeply bilobed, calyculate and noncapitate; hemipenial lobes cylindrical, narrower towards the capitulum; in sulcate and asulcate views, lobe crotch ornamented with densely packed small spines that become larger distally; sulcus spermaticus centrolineal, bifurcate and with walls strongly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal half of each hemipenal lobe densely ornamented with small calyces with strongly defined spinulate edges. In sulcate view, hemipenial body surface with small spinules medially, but with a pair of enlarged and strongly calcified lateral spines (basal hooks) followed by 4–5 rows of smaller obliquely-arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with mesial and lateral spines about half the size of the basal hook; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes with rows of spines, but otherwise non-spiculate; distal half of lobes strongly calyculate. In asulcate view, the center of hemipenial body covered with scattered spinules; hemipenial lobes ornamented with 3 rows of spines.

Figure 24.

Hemipenial architecture of Bothriechis rasikusumorum sp. nov. in sulcate, lateral, and asulcate views. ICN 11164 from Parque Nacional Cueva de Los Guácharos, Huila department, Colombia. Photos by Duván Zambrano.

An adult male, SVL 536 mm, tail length 114 mm (21.3% SVL); head length 30.2 mm (5.6% SVL) from tip of snout to angle of jaw; head width 24.2 mm (80.1% head length) taken at broadest point; rostral broader than high (4.2 × 2.3 mm); nasal not entirely divided; incomplete suture between nasal and first supralabial; loreal about 1/3 size of pit, contacting postnasal, 1 canthal, 1 suprafoveal, 2 prefoveals, lacunolabial, and preocular; prefoveals 5/4; subfoveals 2/2; postfoveals 0; prelacunal fused with second supralabial on the right side; sublacunals 2/2 (one of which is small and granular); supralacunal elongated and in contact with orbit; preoculars 1/1 (2/2 if supralacunal is considered a preocular); suboculars 1/1; postoculars 1/1; loreal pit large, directed anteriorly, located slightly below line drawn from center of eye to naris; supralabials 8/8 (including lacunolabial); infralabials 11/11, first pair barely fail to meet posteriorly due to stretched skin; mental broader than long (4.2 × 2.3 mm); 1 pair of chinshields; 5 pairs of gulars between chinshields and preventrals; preventrals 1; anterior internasals 2; canthals 3/2; supraciliary scales low and granular with the exception of a pair of raised and triangular scales; supraoculars B-shaped, 2.5× longer than wide; intersupraoculars 5; anterior dorsal head scales smooth; posterior head scales barely keeled; interrictals 27; dorsal scale rows 23/23/19; ventrals 147; cloacal plate entire; 56 undivided subcaudals; tail prehensile.

Bothriechis rasikusumorum sp. nov. is an arboreal snake that inhabits montane cloud forests and coffee plantations (Erik Gaitan, pers. comm.). Vipers of this species have been seen at night or during the day, either on leaf-litter or on low understory vegetation less than 2 m above the ground.

We know of no snakebites caused by this species in Colombia nor any studies on the venom that could be assigned to this species.

Bothriechis rasikusumorum sp. nov. is known from at least 26 localities (listed in Suppl. material 3) along the upper watershed of the Río Magdalena in Huila department, Colombia. The species occurs over an area of approximately 6,578 km² along the eastern slope of Cordillera Central and on both slopes of Cordillera Oriental at elevations 1,298–2,180 m above sea level (Fig. 3).

The specific epithet rasikusumorum is a patronym honoring Rasik Shah (1939–2022), Kusum Shah (1942–present), and their grandson Oscar Shah. The Shah family helped fund the expedition that led to the discovery of this new species.

We consider Bothriechis rasikusumorum sp. nov. to be included in the Vulnerable category following the IUCN criteria B1a, b (i, iii, iv) (IUCN 2012), because the species’ extent of occurrence is estimated to be much less than 20,000 km² (Fig. 3) and its habitat is severely fragmented and declining in extent and quality due to deforestation. Although B. rasikusumorum sp. nov. occurs in three protected areas (Parque Nacional Cueva de los Guácharos, Bosque Protector Pompeya, and Reverva Chiyurco), most localities where the species has been recorded (Suppl. material 1) are in forest patches surrounded by a matrix of pastures and plantations. Based on the species distribution model presented in Fig. 3 in combination with maps of vegetation cover of Colombia (IDEAM 2014), we estimate that nearly 71% of the forest cover throughout the species’ potential distribution area has been destroyed, mostly due to the expansion of the agricultural frontier. One of us (JV) interviewed coffee plantation workers in Huila, who report that they routinely kill these vipers when found. During a 10-night expedition to Huila department, a group of three field biologists led by JV failed to find a single specimen in four of the localities where the species has been reported nearby the city Pitalito.

Holotype : ZSFQ 5055 (18), adult female collected on January 1, 2017 at Tundaloma Lodge, Esmeraldas province, Ecuador (1.18236, -78.7525; 74 m).

Paratypes : All labeled Bothriechis rahimi sp. nov. in Suppl. material 1.

Rahim’s Eyelash-Pitviper.

Víbora de pestañas de Rahim.

Bothriechis rahimi sp. nov. is diagnosed based on the following combination of characters: (1) two or three raised triangular or spinelike supraciliary scales; (2) anterior dorsal head scales keeled; (3) gular scales much smaller than chinshields; (4) 8–13 interoculolabials; (5) 4–5 canthals, some raised slightly forming a ridge along the canthus; (6) loreal not in contact with preocular; (7) yellow morph present; (8) dorsal bands pink and faint; (9) opposing kidney shaped dorsal marks absent; (10) black speckles on dorsal scales absent; (11) black speckling on ventral surfaces absent; (12) ventral surfaces entirely white in some individuals; (13) iris pale straw yellow with fine black speckles; (14) 21–23 dorsal scale rows at mid-body; (15) 137–145 ventrals in males, 146–151 in females; (16) maximum total length in males 336 mm, in females 494 mm.

Bothriechis rahimi sp. nov. is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from all of them by having supraciliaries raised, anterior dorsal head scales keeled, 8–13 interoculolabials, faint pink dorsal bands, and low number of ventrals in both males and females. It is one of the two members of the SA Bothriechis group where the golden morph has been recorded (Fig. 26c), albeit it is not identical to the B. nigroadspersus golden morph (Fig. 5a–c), as it has faint pink bands. Bothriechis rahimi sp. nov. resembles B. torvus and B. nitidus. From the former, the new species differs by being smaller in body size, having less than 148 ventrals in males, supraciliaries spinelike (vs broad and triangular), and presence of yellow morph and red morph. From B. nitidus, the new species differs by being smaller in body size, having raised supraciliaries (vs low), a higher number of canthals (4–5 vs 2–3) and interoculolabials (8–13 vs 3–8), scales on the anterior dorsal surface of the head keeled (vs smooth), presence of a yellow morph, and lack of a green morph (all B. nitidus examined are green; Suppl. material 1).

Figure 25.

Adult female holotype of Bothriechis rahimi sp. nov. ZSFQ 5055 in a. Dorsal and b. Ventral view. Photos by Alejandro Arteaga.

Figure 26.

Photographs of living specimens of Bothriechis rahimi sp. nov. from Tundaloma Lodge, Esmeraldas province, Ecuador. a. Adult female; b. MZUTI 3325 adult male; and c. ZSFQ 5053 adult female. Photos by Lucas Bustamante, Alejandro Arteaga, and Frank Pichardo.

An adult female, SVL 374 mm, tail length 71 mm (18.9% SVL); head length 26.8 mm (7.2% SVL) from tip of snout to angle of jaw; head width 20.5 mm (76.5% head length) taken at broadest point; rostral broader than high (3.2 × 2.5 mm); nasal divided and not fused with first supralabial; loreal about 1/5 size of pit, contacting postnasal, canthals, prelacunal, and supralacunal; prefoveals 4/2; subfoveals 1/0; postfoveals 0; prelacunal fused with second supralabial; sublacunals 2/2; supralacunal elongated and in contact with orbit; preoculars 1/1 (2/2 if supralacunal is considered a preocular); suboculars 1/1; postoculars 2/3; loreal pit large, directed anteriorly, located slightly below line drawn from center of eye to naris; supralabials 9/8 (including lacunolabial); infralabials 12/12, first pair meet posteriorly; mental broader than long (3.2 × 2.8 mm); 1 pair of chinshields; 6 pairs of gulars between chinshields and preventrals; preventrals 1; anterior internasals 3; canthals 4/5; 2/2 triangular and raised supraciliary scales; supraoculars oblong with irregular borders, 1.8× longer than wide; intersupraoculars 6; anterior dorsal head scales keeled; posterior head scales keeled; interrictals 30; dorsal scale rows 27/23/19; ventrals 151; cloacal plate entire; 51 undivided subcaudals; tail prehensile.

Bothriechis rahimi sp. nov. is an arboreal snake that inhabits evergreen lowland forests usually within 25 km from the coastline. We have found vipers of this species active at night perched on stems, branches, and tangled vegetation 0.4–8 m above the ground. One individual was perched in hunting posture on a heliconia stem facing the flowers of the plant, presumably on the wait for hummingbirds. One individual was found feeding on a treefrog (Smilisca phaeota) and another one regurgitated an unidentified Pristimantis species, probably P. esmeraldas (field observations by Javier Aznar and JHV).

We know of only one snakebite cause by this species in Ecuador. A photographer was bitten on the right index finger by MZUTI 3332. The victim experienced intense local pain and swelling but recovered shortly after receiving three doses of polyvalent antivenom (elaborated by Instituto Clodomiro Picado).

Bothriechis rahimi sp. nov. is known from at least 12 localities (listed in Suppl. material 3) along the mouths of the rivers Esmeraldas, Santiago, Cayapas, and Mira in extreme northwestern Ecuador and southwestern Colombia. The species occurs over an area of approximately 6,003 km² of the Chocó biome and has been recorded at elevations of 11–200 m above sea level (Fig. 3). Approximately 7.6% of the predicted area of distribution of B. rahimi sp. nov. overlaps with that of B. nitidus, but we did not find evidence of sympatry between the two species.

The specific epithet rahimi is a patronym honoring Prince Rahim Aga Khan, a firm environmentalist who has inspired many with his work focused on tackling climate change, primarily in countries where the Aga Khan Development Network is active, alongside his brother Prince Hussain Aga Khan.

We consider Bothriechis rahimi sp. nov. to be included in the Vulnerable category following the IUCN criteria B1a, b (i, iii, iv) (IUCN 2012), because the species’ extent of occurrence is estimated to be much less than 20,000 km² (Fig. 3) and its habitat is severely fragmented and declining in extent and quality due to deforestation. Although B. rahimi sp. nov. occurs in two protected areas (Reserva Awá and Refugio de Vida Silvestre La Chiquita), the remaining ten localities where the species has been recorded (Suppl. material 3) are in heavily human-modified areas. Based on the species distribution model presented in Fig. 3 in combination with maps of vegetation cover of Colombia (IDEAM 2014) and Ecuador (MAE 2012), we estimate that nearly 49% of the forest cover throughout the species’ potential distribution area has been destroyed, mostly due to the expansion of the agricultural frontier.

All labeled Bothriechis nitidus in Suppl. material 1.

Ecuadorian Eyelash-Pitviper.

Víbora de pestañas ecuatoriana, cabeza de candado, equis voladora (Manabí), papagayo (Santo Domingo de los Tsáchilas), zampiña (cloud forest populations).

Bothriechis nitidus is diagnosed based on the following combination of characters: (1) supraciliary scales low and granular or two pointed but not raised; (2) anterior dorsal head scales smooth or barely keeled; (3) gular scales usually much smaller than chinshields or similar in size to chienshields in some cloud forest populations; (4) 3–8 interoculolabials; (5) 2–3 canthals, raised slightly and forming a ridge along the canthus; (6) loreal not in contact with preocular; (7) yellow morph absent; (8) dorsal bands dark reddish brown, red, or pink; (9) no opposing kidney shaped dorsal marks; (10) black speckles on dorsal scales usually absent, but present in some cloud forest populations; (11) black speckling on ventral surfaces usually absent, but present in some cloud forest populations; (12) ventral surfaces entirely white in some individuals; (13) iris pale golden yellow to light green with or without black speckles or spots; (14) 19–23 dorsal scale rows at mid-body; (15) 129–156 ventrals in males, 132–158 in females; (16) maximum total length in males 594 mm, in females 857 mm.

Bothriechis nitidus is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from all of them by having supraciliaries not raised, a low number of canthals (2–3) and interoculolabials (3–8), a low number of ventral scales, and a green dorsum with dark reddish brown, red, or pink bands (Fig. 27). Bothriechis nitidus resembles B. hussaini sp. nov., but this other species occurs south of the known distribution of B. nitidus and is characterized by having the loreal scale in contact with the preocular (not in contact in B. nitidus), supralabials spotted, dorsal scales densely stippled with black pigment, black-spotted ventral surfaces, and basal hooks of hemipenial body 4X (instead of 2X) the size of adjacent spines. Also, unlike B. nitidus, the golden morph is present in B. hussaini sp. nov. Bothriechis nitidus also resembles B. rahimi sp. nov., but this other species occurs north of the known distribution of B. nitidus and is characterized by having two or three raised and spinelike supraciliary scales, keeled anterior dorsal head scales, a higher number of interoculolabials (8–13 vs 3–8), canthals (4–5 vs 2–3), and a completely different array of color morphs, including red and pink.

Figure 27.

Photographs of living specimens of Bothriechis nitidus from Ecuador. a. AMARU SN adult female from Santa Rosa, Pichincha province; b. Adult from Reserva FCAT, Esmeraldas province; c. Juvenile from Verde Bambú, Pichincha province; d. Juvenile from Canandé Biological Reserve, Esmeraldas province; e. Adult from Gualpi, Esmeraldas province; f. Adult from Bosque Protector La Perla, Esmeraldas province; g. Adult from Santa Lucía Reserve, Pichincha province; h. Adult from Reserva FCAT, Esmeraldas province; i. Juvenile from Santa Lucía Reserve, Pichincha province; j. Juvenile from Canandé Biological Reserve, Esmeraldas province. Photos by Jose Vieira, Alejandro Arteaga, and Sebastián Di Doménico.

(n = 3; Fig. 28) Everted and inflated, the organ is deeply bilobed, calyculate and noncapitate; hemipenial lobes cylindrical, but tapering towards the capitulum; in sulcate and asulcate views, lobe crotch ornamented with densely packed spinules and spines that become larger distally; sulcus spermaticus centrolineal, bifurcate and with walls strongly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal one third to one half of each hemipenal lobe densely ornamented with small calyces with strongly defined spinulate edges. In sulcate view, hemipenial body surface with small spinules medially, basal hooks present, and 2–3 rows of smaller obliquely-arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with mesial and lateral spines about half the size of the basal hooks; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes with rows of spines, but otherwise non-spiculate; distal half strongly calyculate. In asulcate view, the center of hemipenial body is nude to sparsely spiculate; hemipenial lobes ornamented with 5 rows of smaller spines (about 1/3 the size of the lateral basal hooks) that decrease in size towards the lobe crotch.

Figure 28.

Hemipenial architecture of Bothriechis nitidus in sulcate, lateral, and asulcate views. a. MZUTI 3753 from Sachatamia Lodge, Pichincha province, Ecuador; b. MZUTI 3754 from Santa Rosa de Intag, Imbabura province, Ecuador; c. ZSFQ 5054 from Canandé Biological Reserve, Esmeraldas province, Ecuador. Photos by Amanda Quezada.

Bothriechis nitidus is an arboreal snake that inhabits evergreen lowland and montane forests, cloud forests, planted forests, plantations (cacao, coffee, and banana), and rural gardens. We have found vipers of this species at night perched on arboreal vegetation up to 10 m above the ground or, rarely, moving at ground level during the daytime. Individuals of B. nitidus are known to prey on frogs (Craugastor longirostris, Pristimantis achatinus, P. walkeri, and Trachycephalus jordani; Valencia et al. 2016; Meza-Ramos et al. 2019), anoles (personal observation by JV), hummingbirds, and mice (Meza-Ramos et al. 2019). Valencia et al. (2016) reports that females of this species give birth to litters of 5–9 young. One specimen (FHGO 7795) lived for 12 years in captivity.

In coastal Ecuador, 0.2–10.3% of snakebites are attributed to this species (Betancourt 2012; Valencia et al. 2016). Kuch et al. (1996) found the venom of this species to be not hemorrhagic, weakly coagulant, and only moderately lethal (LD50 estimated as 6.5 mg/kg).

Bothriechis nitidus is endemic to Ecuador. It is known from at least 121 localities (listed in Suppl. material 3) along the Chocoan lowlands and adjacent foothills of the Andes in Ecuador. The species occurs over an area of approximately 37,400 km² and has been recorded at elevations of 0–2,230 m above sea level (Fig. 3). An estimated 4.2% of the predicted area of distribution of B. nitidus overlaps with that of B. hussaini sp. nov. and we found evidence (MZUA.Re.288 and JM 75; Fig. 3) of sympatry between the two species where the model predicted it. Both species co-occur along the foothills of the Andes in the sector between Naranjal, Guayas province, and Cumandá, Chimborazo province. An estimated 3.3% of the predicted area of distribution of B. nitidus overlaps with that of B. rahimi sp. nov., but we did not find evidence of sympatry between the two species.

The specific epithet nitidus is a Latin word meaning “shining” or “elegant.” It refers to the eye-catching dorsal pattern of the holotype, which is shared by most individuals of lowland populations of this species (Fig. 27).

We consider Bothriechis nitidus to be included in the Near Threatened category following IUCN Red List criteria (IUCN 2012) primarily because the species’ extent of occurrence is estimated to be larger than the 20,000 km² needed to meet B1 criteria for the Vulnerable category. However, although the species occurs in numerous protected areas (no less than 30; see Suppl. material 3), the majority of the species’ forest habitat has been destroyed. Based on the distribution model presented in Fig. 3 in combination with maps of vegetation cover of Ecuador (MAE 2012), we estimate that only ~32% of the species’ forest habitat is still standing.

Holotype : ZSFQ 5056 (Figs 29, 30g), subadult male collected on June 11, 2019 at Buenaventura Biological Reserve, El Oro province, Ecuador (-3.65467, -79.76794; 524 m).

Paratypes : All labeled Bothriechis hussaini sp. nov. in Suppl. material 1 from museum collections AMNH, DHMECN, MZUA, and ZSFQ.

Hussain’s Eyelash-Pitviper.

Víbora de pestañas de Hussain.

Cabeza de candado, víbora sol (yellow morph).

Bothriechis hussaini sp. nov. is diagnosed based on the following combination of characters: (1) supraciliary scales low and granular to triangular; (2) anterior dorsal head scales smooth or barely keeled; (3) gular scales 1/2 size of chinshields; (4) 5–8 interoculolabials; (5) 2–3 canthals, which may be flat or slightly raised forming a ridge along the canthus; (6) loreal in contact with preocular; (7) yellow morph present; (8) dorsal bands black or pink or a combination of both; (9) opposing kidney shaped dorsal marks absent; (10) black speckles on dorsal scales present; (11) black speckling on ventral surfaces prominent; (12) ventral surfaces never entirely white; (13) iris green to yellow with fine black speckles, spots, or reticulations; (14) 21–23 dorsal scale rows at mid-body; (15) 140–151 ventrals in males, 147–153 in females; (16) maximum total length in males 608 mm, in females 656 mm.

Bothriechis hussaini sp. nov. is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2). It differs from all of them by having supraciliaries not raised, a low number of canthals (2–3) and interoculolabials (5–8), a low number of ventral scales, and a green dorsum heavily speckled with black pigment (Fig. 30). Bothriechis hussaini sp. nov. is similar to B. nitidus, but differs from this species by having the loreal scale in contact with the preocular (not in contact in B. nitidus), supralabials heavily marked by black speckles, dorsal and ventral scales densely stippled with black pigment, basal hooks of hemipenial body 4X (instead of 2X) the size of adjacent spines (Fig. 31), and by the presence of a yellow morph (=víbora sol; Fig. 30b). Bothriechis nitidus also resembles B. rahimi sp. nov., but this other species occurs north of the known distribution of B. nitidus and is characterized by having two or three raised and spinelike supraciliary scales, keeled anterior dorsal head scales, a higher number of interoculolabials (8–13 vs 3–8), canthals (4–5 vs 2–3), and a completely different array of color morphs, including pale gray and pink (Fig. 26).

Figure 29.

Adult male holotype of Bothriechis hussaini sp. nov. ZSFQ 5056 in a. Dorsal and b. Ventral view. Photos by Alejandro Arteaga.

Figure 30.

Photographs of living specimens of Bothriechis hussaini sp. nov. from Ecuador. a. CZ-003 adult female from El Colorado, El Oro province; b. CZ-001 adult male from El Colorado, El Oro province; c. CZ-004 adult male from San Carlos, Guayas province; d. ZSFQ 5058 juvenile female from Buenaventura Biological Reserve, El Oro province; e. AMARU SN adult female Buenaventura Biological Reserve, El Oro province; f. subadult of undetermined sex from Buenaventura Biological Reserve, El Oro province; g. ZSFQ 5056 adult male holotype from Buenaventura Biological Reserve, El Oro province. Photos by Alejandro Arteaga and Jose Vieira.

Figure 31.

Hemipenial architecture of Bothriechis hussaini sp. nov. in sulcate, lateral, and asulcate views. a. MZUTI 5872 and b. ZSFQ 5056 from Reserva Biológica Buenaventura, El Oro province, Ecuador. Photos by Amanda Quezada.

(n=2; Fig. 31) Everted and inflated, the organ is deeply bilobed, calyculate and noncapitate; hemipenial lobes cylindrical to spindle-shaped; in sulcate and asulcate views, lobe crotch ornamented with scattered spinules proximally and larger spines distally; sulcus spermaticus centrolineal, bifurcate and with walls strongly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal half of each hemipenal lobe densely ornamented with small calyces with strongly defined spinulate edges. In sulcate view, hemipenial body surface with small mesial spinules, a pair of enlarged calcified spines (basal hooks), and 3–4 rows of smaller obliquely-arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with mesial and lateral spines about 1/4 the size of the basal hooks; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes with rows of spines, but otherwise non-spiculate; distal half strongly calyculate. In asulcate view, the center of hemipenial body is nude to sparsely spiculate; hemipenial lobes ornamented with 4 rows of smaller spines (about 1/4 the size of the lateral basal hooks) that decrease in size towards the lobe crotch.

An adult male, SVL 358 mm, tail length 51+ mm (14.3% SVL; tail-tip missing); head length 29.2 mm (8.2% SVL) from tip of snout to angle of jaw; head width 21.6 mm (73.9% head length) taken at broadest point; rostral broader than high (3.1 × 1.9 mm); nasal completely divided and not fused with first supralabial; loreal about 1/2 size of pit, contacting nasal, canthals, 2 prefoveals, prelacunal, supralacunal, and preocular; prefoveals 4/5; subfoveals 2/2; postfoveals 0; prelacunal not fused with second supralabial; sublacunals 2/2; supralacunal elongated and in contact with orbit; preoculars 1/1 (2/2 if supralacunal is considered a preocular); suboculars 1/1; postoculars 1/1; loreal pit large, directed anteriorly, located slightly below line drawn from center of eye to naris; supralabials 8/9 (including lacunolabial); infralabials 11/11, first pair meet posteriorly; mental broader than long (3.2 × 2.0 mm); 1 pair of chinshields; 5 pairs of gulars between chinshields and preventrals; preventrals 0; anterior internasals 3; canthals 3/3; supraciliary scales low and granular, with one on the left side triangular; supraoculars kidney-shaped, 2.2× longer than wide; intersupraoculars 7; anterior dorsal head scales slightly keeled; posterior head scales strongly keeled; interrictals 28; dorsal scale rows 25/23/17; ventrals 152; cloacal plate entire; 38+ undivided subcaudals (tail incomplete); tail prehensile.

Bothriechis hussaini sp. nov. is an arboreal snake that inhabits evergreen lowland/foothill forests and plantations (coffee and banana). We have found vipers of this species at night or during the day perched on vegetation up to 1.2–3 m above the ground. Meza-Ramos et al. (2010) found a mouse of the genus Oryzomys in the stomach of DHMECN 2580 from El Oro province, Ecuador.

One biologist who was bitten in the shoulder by a Bothriechis hussaini sp. nov. from Azuay province reports intense localized pain, swelling, and tachycardia with two hours from the incident (personal comments to AA, 2022). The patient received antihistamines as treatment and recovered fully within 24 hours of the bite.

Bothriechis hussaini sp. nov. is known from at least 55 localities (listed in Suppl. material 3) along the Pacific lowlands and adjacent Andean foothills in southwestern Ecuador and extreme northwestern Peru. The species occurs over an area of approximately 13,591 km² in the transition area between the humid Chocó rainforests and the Tumbesian dry forests and has been recorded at elevations 1–1,680 m above sea level (Fig. 3). Approximately 11.7% of the predicted area of distribution of B. hussaini sp. nov. overlaps with that of B. nitidus and we found evidence (MZUA.Re.288 and JM 75) of sympatry between the two species where the model predicted it. Both species co-occur along the foothills of the Andes in the sector between Naranjal, Guayas province, and Cumandá, Chimborazo province.

The specific epithet hussaini is a patronym honoring Prince Hussain Aga Khan, who has devoted his life, influence, and wealth to environmental conservation since he was eleven years old. In 2014, he created a Swiss-based non-profit called Focused On Nature (FON), through which he protects endangered global biodiversity through local organizations worldwide.

We consider Bothriechis hussaini sp. nov. to be included in the Vulnerable category following the IUCN criteria B1a, b (i, iii, iv) (IUCN 2012), because the species’ extent of occurrence is estimated to be much less than 20,000 km² (Fig. 3) and its habitat is severely fragmented and declining in extent and quality due to deforestation. Although B. hussaini sp. nov. occurs in four protected areas (Reserva Ecológica Manglares Churute, Reserva Biológica Buenaventura, Reserva Forestal Cerro Samama, and Reserva Nacional Tumbes), the remaining localities where the species has been recorded (Suppl. material 3) are historical and probably do not represent extant populations. Based on the species distribution model presented in Fig. 3 in combination with maps of Ecuador (MAE 2012), we estimate that approximately 78% of the forest cover throughout the species’ potential distribution area has been destroyed, mostly due to the expansion of the agricultural frontier.