Open-access, online, rapid taxonomy
ISSN: 2653-4649 (Online)

Australian Journal of

Taxonomy

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A new species of the jumping spider genus Opisthoncus (Araneae: Salticidae) from southeastern Australia, with a redescription of Opisthoncus sexmaculatus

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John C. Douglas

Queen Victoria Museum and Art Gallery, 2 Invermay Road, Invermay, Launceston, Tasmania 7248, Australia

jcdouglas46@hotmail.com

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Abstract

Opisthoncus mileshendyi is newly described from Tasmania and Victoria (Australia). The diagnosis, description and diagnostic figures are given, and remarks on distribution, biology and relationships are provided. Along with this previously undescribed species of Opisthoncus, this paper also provides a redescription of the female of Opisthoncus sexmaculatus (C.L. Koch, 1846). This paper also describes the previously undescribed male of the same species.

urn:lsid:zoobank.org:pub:F30E7A4E-0A1B-4F27-A507-AAE4679C45B6

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Introduction

Jumping spiders are one of the most diverse spider families in the world with over 6815 species (WSC, 25 June 2025); 501 of which have been recorded from Australia (AFD, 18 April 2025). Opisthoncus is one of 91 salticid genera occurring in Australia (AFD, 18 April 2025). They are quite large and often easily recognised, at least to genus. Unusually males have enlarged chelicerae with characteristically large fused teeth; females are not so dramatically modified. A common feature of the genus is the small cephalic protuberance located centrally in a dark band between the posterior lateral eyes. Many of the species have a double row of dark patches or figures along the dorsal surface of the abdomen as observed in the two species described here. This is another feature of the genus. Very little is known of their biology, mating behaviour and little of their taxonomy.

The genus Opisthoncus (L. Koch, 1880 ), includes 32 described species (World Spider Catalogue, version 26), 25 of which were treated by Gardzinska & Żabka (2013). Species of Opisthoncus have been reported Australia-wide, New Guinea and Lord Howe Island, but not in Norfolk, Christmas or Cocos Keeling Islands. Since 1920, no new species have been added to the list. The genus is clearly understudied owing to the number of species collected for which there is no description and according to Marek Zabka (pers. comm.), some 100 species can be expected in Australia, including Tasmania.

Specimens of a distinctive species of Opisthoncus have been observed around Launceston which could not be assigned to a described species. However, it appeared to be similar to O. sexmaculatus (C.L. Koch, 1846) (see C.L. Koch, 1846; Simon, 1903; Gardzińska & Zabka, 2013) (Fig. 1) (Fig. 6), as indicated by the double row of dark patches along the abdomen. This paper provides a description of the Tasmanian species (which is also recorded from Victoria) and is compared with O. sexmaculatus, which is redescribed from specimens collected in Western Australia.

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Materials & Methods

Microscopic photos were taken with a Leica EZ4 W microscope with inbuilt camera linked to an Apple Macbook Pro. Multiple images were taken on different focal planes and combined using Photoshop software.

Habitus photographs of Opisthoncus mileshendyiwere taken using an Olympus TG6 using inbuilt image stacking. Opisthoncus sexmaculatus habitus photos were taken with a Canon EOS R5 and a Canon 100mm rf speedlight macro lens.

Map diagrams by author.

Measurements are given in millimetres.

Abbreviations used in the text are as follows:

CL cephalothorax length, CW cephalothorax width, CH cephalothorax height, AL abdomen length, AW abdomen width, AEW anterior eye row width, PEW posterior eye row width, EFL eye field length, PLE posterior lateral eyes, L1 leg 1, QVM Queen Victoria Museum and Art Gallery, Launceston, Tasmania, WAM West Australian Museum, ALA Atlas of Living Australia.

Specimens of the new species were collected by beating of tree branches. After photographing live spiders, they were euthanased by freezing, then preserved in 80% Ethanol. Prior to examination, dissected female genitalia cleared in lactic acid for 24 hours at room temperature.

Specimens of Opisthoncus mileshendyi are deposited in the collection of the Queen Victoria Museum, Launceston, Tasmania, while specimens of Opisthoncus sexmaculatus are held at the West Australian Museum and the lectotype female at the Museum für Naturkunde, Berlin.

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Results

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Discussion

Distribution

The spiders of the new species were collected in Churchill Park, Invermay, Launceston, northern Tasmania (Fig. 2). After extensive searching in the same parkland, no further specimens were found however, specimens were collected from the same tree over an 18 month period. Subsequently another specimen was found at a roadside stop at Paramatta Park, 79 kilometres to the north-east. No other specimens have been recorded from Tasmania. (Fig. 3). One specimen has also been recorded from Victoria.

The second species, Opisthoncus sexmaculatus, treated here occurs in coastal Western Australia (Fig. 9).

According to the Atlas of Living Australia, occurrences of O. sexmaculatus have been recorded 767 times, mostly from Queensland, New South Wales, Victoria and Western Australia, with 1 specimen recorded for Tasmania. As none of the specimens shown on ALA are substantiated by documentary or microscopic evidence, but are of human observation it cannot be verified that the specimens are actually O. sexmaculatus. However, from the images shown most appear to be of the new species described here, apart from the four specimens shown to be from Western Australia which are consistent with O. sexmaculatus.

Despite intense sampling of spiders around Tasmania conducted over the last 10 years, no other specimens of this O. mileshendyihave been collected. This does not preclude that other localities of the species may exist in unsampled areas. It is also notable that within the park where the species occurred, no specimens were found on other species of trees, or other blackwood trees.

While O. mileshendyi is unusual in Tasmania, it is only one of a number of Opisthoncus species that are commonly found around the state that have not yet been described.

Biology

The specimens of O. mileshendyi were collected from the foliage of one particular blackwood tree (Acacia melanoxylon) (Fig. 2). Also found with these spiders were other species, including crab spiders (Thomisidae), sac spiders (Clubionidae), numerous small cockroach nymphs (Blattidae) and small caterpillars. The cockroaches are numerous and being soft bodied, make good prey for the jumping spiders.

Living specimens of the Opisthoncus sexmaculatus photographed were exclusively found on the leaves of the grass tree (Xanthorrhoea preissii) (Fig. 6 D), a Western Australian native shrub. Other preserved specimens also have been recorded on the grass tree.

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Table content

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Key title

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Taxonomy

Family Salticidae

Subfamily Salticinae

Genus Opisthoncus L. Koch, 1880

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Acknowledgments

I wish to thank Dr Robert Raven (Queensland Museum) for his continued support and assistance with technical issues, Professor Marek Żabka (University of Siedlce, Poland) for his editorial assistance and encouragement to continue the description of the Opisthoncus genus of Salticids, my arachnophobic wife Rainie Douglas for her tolerance of my obsession with spiders, Alfonsina Arriaga-Jiménez, Senior Curator, Natural Sciences, for her editorial help, Simon Fearn and Judy Rainbird, Collections Officers Natural Sciences at the Queen Victoria Museum, Launceston for their support and encouragement to complete this project. Thanks too to Jason Dunlop, curator of arachnids and myriapods at the Museum für Naturkunde, Berlin for locating C.L. Koch’s specimen of Plexippus (Opisthoncus) sexmaculatus, Oskar Werb for taking photographs of the original female specimen and Kaylene Taylor for her photographs of live Opisthoncus sexmaculatus spiders. Robert Douglas for grass tree photo. Also Dr Volker Framenau for selecting specimens from the WAM collection and Julianne Waldock for arranging for specimens to be sent for my research.

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Supplementary Material

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References

Gardzinska, J & Żabka, M. 2013. Redescription of the genus Opisthoncus, L. Koch 1880 (Araneae: Salticidae). Zootaxa 3717: 401-447.

Koch, C. L. (1846). Die Arachniden. J. L. Lotzbeck, Nürnberg, Dreizehnter Band, pp. 1-234, pl. 433-468 (f. 1078-1271); Vierzehnter Band, pp. 1-88, pl. 467-480 (f. 1272-1342).

Simon, E. (1903a). Histoire Naturelle des Araignées. Deuxième édition, tome second. Roret, Paris, pp. 669-1080.

Whyte, R. and Anderson, G. 2017. A Field Guide to the Spiders of Australia, CSIRO Publishing, Clayton South, Victoria.

Żabka, M. (1991c). Studium taksonomiczno-zoogeograficzne nad Salticidae (Arachnida: Araneae) Australii. Wyższa Szkola Rolniczo-Pedagogiczna w Siedlcach Rozprawa Naukowa 32 1-110.

Atlas of Living Australia. https://www.ala.org.au/

Arachne.org.au. https://www.arachne.org.au/

Australian Faunal Directory. https://biodiversity.org.au/afd/taxa/SALTICIDAE/statistics (Accessed June 2025)

Australian National Herbarium. https://www.cpbr.gov.au/biography/preiss-ludwig.html

World Spider Catalog (2025) World Spider Catalog, version 26, available from http://wsc.nmbe.ch (Accessed June 2025)

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Open-access, online, rapid taxonomy ISSN: 2653-4649 (Online)

Australian Journal of

Taxonomy

Open-access, online, rapid taxonomy
ISSN: 2653-4649 (Online)