Research Article |
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Corresponding author: Pedro de S. Castanheira ( pedro.castanheira@murdoch.edu.au ) Academic editor: Danilo Harms
© 2023 Giullia de F. Rossi, Pedro de S. Castanheira, Renner L. C. Baptista, Volker W. Framenau.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Rossi GF, Castanheira PS, Baptista RLC, Framenau VW (2023) Venomius, a new monotypic genus of Australian orb-weaving spiders (Araneae, Araneidae). Evolutionary Systematics 7(2): 285-292. https://doi.org/10.3897/evolsyst.7.110022
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A new monotypic Australian genus in the orb-weaving spider family Araneidae Clerck, 1757 is described, Venomius gen. nov., with V. tomhardyi sp. nov. as type species. Somatically, Venomius gen. nov. is similar to the typical leaf-curling orb-weaving spiders, such as Phonognatha Simon, 1894 or Leviana Framenau & Kuntner, 2022, due to a similar elongate cylindrical abdomen and colouration; however, the genital morphology of the new genus is very different. Most unusual are the presence of two strong macrosetae on the male pedipalp tibia. Male pedipalp sclerites are complex, with diagnostic characters including the tibial macrosetae and a keeled median and a rounded basal process on the stipes. The epigyne of females is wholly covered by the scape that has a short median process. Venomius tomhardyi gen. nov. et sp. nov. has been collected in southern Australia, from Tasmania to Western Australia, where it builds a circular, vertical orb-web. Spiders often hide in silk-lined hollows in branches of trees when disturbed during the day.
Australia, systematics, monotypy, taxonomy
With 223 described species in 41 genera, the orb-weaving spider family Araneidae Clerck, 1757 is the third-largest spider family in Australia (
Like other araneoids, such as the Linyphiidae Blackwall, 1859 and Theridiidae Sundevall, 1833, there is high genus level diversity in the Araneidae, resulting in many genera with a small number of species. Fifteen of the Australian araneid genera include five or less species; of these, four are currently monotypic: Abba Castanheira & Framenau, 2023, Cyrtobill Framenau & Scharff, 2009, Lariniophora Framenau, 2011 and Quokkaraneus Castanheira & Framenau, 2022 (see also
During a recent field trip in southern Australia, we collected a large number of specimens of an unusual species of orb-weaving spiders that did not display the synapomorphies of any of the recently revised genera nor any other genus known to us. Somatic morphology, particularly the somewhat elongate and cylindrical abdomen without any humeral or posterior humps, resembled that of leaf-curling orb-weavers, such as Phonognatha Simon, 1894 or Leviana Framenau & Kuntner, 2022 (see
We here propose a new monotypic genus to harbour this unusual species as part of an ongoing revision of Australian Araneidae. Due to its unusual morphology, we are not able to place the species in any of the established subfamilies of orb-weaving spiders or any of the informal clades proposed by
This study was triggered by specimens collected during our recent fieldtrip targeting orb-weaving spiders in southern Australia, although the new species had already been known from a few records in Australian museums. Overall, this study is based on an examination of more than 12,000 Araneidae records (= vials) as part of an ongoing revision of Australian Araneidae that commenced in 2005.
Descriptions and terminology follow recent publications on Australian Araneidae (e.g.,
The male pedipalp was expanded by alternatively submerging it for around 10 min in 10% KOH and distilled water until fully expanded. The terminology of the views of the male pedipalp considers its position as a limb. In Araneidae, the pedipalp is twisted so that the cymbium is situated mesally; therefore, the full view of the bulb with the cymbium in the background is retrolateral. We here recognise two new sclerites on the pedipalp stipes, i.e. a transverse median keel and a basal protrusion. The epigyne was cleared by submerging it for around 10 min in 10% KOH. It has two main parts, the base (encapsulating the internal genitalia) and the scape.
Microscopic photographs were taken at different focal planes with a set-up of a Leica DMC4500 digital camera mounted to a Leica M205C stereomicroscope, and combined using the Leica Application Suite X, v. 3.6.0.20104. All photos were edited and combined to plates with Photoshop CC 2023.
All measurements are given in millimetres. They were taken with an accuracy of one tenth of a millimetre, except for eye and labium measurements taken with an accuracy of one hundredth of a millimetre.
Maps were compiled in the software package QGis v. 3.2.6 Buenos Aires (https://qgis.org/en/site/; accessed 14 July 2023). For specimens collected during our own recent field trip, geographic coordinates were approximated using Google Earth Pro v. 7.3.6.9345 to the nearest tenths of a second of Latitude and Longitude. For other museum specimens, these data were extracted directly from original labels or the registration information, or estimated to the closest minute of Latitude and Longitude in Google Earth Pro.
Morphology
ALE anterior lateral eyes
AME anterior median eyes
PLE posterior lateral eyes
PME posterior median eyes
Collections
SAM South Australian Museum, Adelaide (Australia)
Order Araneae Clerck, 1757
Family Araneidae Clerck, 1757
Venomius tomhardyi sp. nov.; by monotypy.
The new genus Venomius is named after the Marvel Comics’ character “Venom”, created by David Michelinie and Todd McFarlane, whose full first appearance was in “The Amazing Spider-Man #300” (published in May 1988), after an alien symbiote bonded with the character Eddie Brock. This genus-group name is a reference to the head of the character Venom, with conspicuous black spots, that resembles the abdomen of our species, specifically the male holotype (Fig.
Somatically, specimens of Venomius gen. nov. resemble those of Phonognatha due to the similar abdomen shape and colouration of both genera (elongate cylindrical with dark brown to black markings dorsally on paler area) (Figs
Within an Australian context, an elongate cylindrical abdomen is also present in Leviana, but genital morphology is also very different in this genus. The male pedipalp in Leviana has a median apophysis with a basal arch over the radix that carries an internal spur, a proposed synapomorphy of this genus (Framenau and Kunter 2022; p. 107). In contrast, Venomius gen. nov. do not have such an arch or spur (Figs
Venomius tomhardyi sp. nov., male, expanded left pedipalp (
Venomius tomhardyi sp. nov., female (
We here identify the following characters to diagnose Venomius gen. nov.: the male pedipalp has two strong macrosetae on the tibia; a finger-like, long paracymbium (Figs
Medium-sized orb-weaving spiders, with males (ca. TL 5.5–6.4) smaller than females (ca. TL 9.1–11.7). Carapace considerably longer than wide, pear-shaped; colour from orange-brown in males to black in females, cephalic area darker in males (Figs
Holotype
male, Launceston, Trevallyn Nature Recreation Area, Stolen Spice Trail, 41°26'33.58"S, 147°05'56.26"E, 10.i.2023, R. Baptista coll. (
Australia: South Australia: 1 female, Coorong, Sandpiper Campground, 36°08'31.17"S, 139°38'24.15"E (
The species epithet is a patronym in reference to the English actor Edward Thomas “Tom” Hardy, who plays the character Eddie Brock and his alter-ego Venom in the super-hero films of the same name.
As for genus; Venomius gen. nov. is monotypic.
Male (based on holotype
Female (based on
Total length males 5.5–6.4 (n = 3). Total length females 9.1–11.7 (n = 5). Colour varies slightly among specimens, particularly females, with the carapace varying from dark brown to black and the abdominal posterior black field varying in size.
There is no clear phenological pattern in the collection data of V. tomhardyi gen. nov. et sp. nov. with mature males and females found in October, December, January, April and June.
Most specimens were found in vertical orb-webs at about 1 to 2 m height in bushland or forest habitat, often near the coast. Webs were found at night, most of them on exposed branches of trees, especially on dead branches or fallen trees, but sometimes also near the trunks inside the leaf cover. The webs usually had a signal line connecting its hub to the branches supporting them, sometimes also connected to silk-lined holes in the branches, especially in the case of females and big juveniles. When disturbed, the spiders quickly followed the signal line and disappeared into the holes. During the day, spiders were found hiding inside the holes or on tree branches after they absorbed the web. Males were spotted at the silk scaffolding of female webs at night (RLCB pers. obs., John Douglas pers. comm.).
As for the genus, which is monotypic (Fig.
This paper constitutes a further contribution to an ongoing revision of the Australian orb-weaving spiders in the family Araneidae (for a summary on previous studies see
Tibial modifications of the male pedipalp are rare in araneids and
The presence of an elongate cylindrical abdomen is a common feature of leaf-curling araneids in both the Phonognathidae/Phonognathinae (
We thank (in no particular order) Graham Milledge (retired), Helen Smith (both