Epopostruma topendi

Epopostruma topendi
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Epopostruma
Species:	E. topendi
Binomial name
Epopostruma topendi Pettit & Andersen, 2021

Epopostruma topendi is a rare species currently known from two single specimens collected in different remote regions in the Top End of the Northern Territory. Both were collected in pitfall traps set in savanna woodlands.

Identification

This species lacks lateral expansions of the postpetiole, and so belong to the E. quadrispinosa group (Shattuck 2000). The presence of pronounced posterolateral but not anterolateral teeth on the postpetiole, along with an entirely smooth gaster, indicates that it is closely allied to Epopostruma areosylva from New South Wales and southeastern Queensland, from which it is readily distinguished by its generally smooth appearance (especially dorsally) and dentate rather than spinose petiole. The only representatives of Epopostruma previously known from far northern Australia are Epopostruma quadrispinosa and Epopostruma monstrosa, both occurring in the wet tropics of North Queensland (Shattuck 2000). They are readily distinguished from E. topendi by their coarser sculpture, lack of posterolateral teeth on the postpetiole, and presence of gastric sculpture.

Keys including this Species

• Key to Epopostruma Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -11° to -14°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: Pettit & Andersen, 2021

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Castes

• 

  Epopostruma topendi holotype worker: (a) frontal head full face; (b) lateral view; (c) dorsal view; (d) petiole and postpetiole in dorsal view (from Pittit & Andersen, 2021, Fig. 1).

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• topendi. Epopostruma topendi Pettit & Andersen, 2021: 142 (w.), figs. 1a-d, AUSTRALIA (Northern Territory).

Type Material

• Holotype, worker, Nitmiluk National Park, Northern Territory, Australia, 14°14′2″S 132°14′28″E, April–May, 2015, S. Oberprieler, 32 163815, Australian National Insect Collection; pitfall trap, sandstone woodland.
• Paratype, 1 worker, Taracumbi, Melville Island, Northern Territory, Australia, 11°37′8″S 130°42′12″E, 27–30 Jul 2009, M. Pettit, 32 163816, Australian National Insect Collection; pitfall trap, savanna woodland.

Taxonomic Notes

Although both known specimens of this species are extremely similar, they have notable differences in the structure of the petiole and postpetiole. In the holotype from Nitmiluk National Park, the petiole is rectangular in dorsal view and the anterior corners are conspicuously dentate (Fig. 2a). In the Melville Island specimen, the petiole is broader and dome-shaped anteriorly and has very small and inconspicuous denticles (Fig. 2b). Furthermore, in the Melville Island specimen the anterolateral corners of the postpetiole are more rounded, and the posterolateral teeth are narrower. We have conservatively described the two specimens as conspecific due to a lack of additional collections and therefore information on intraspecific variation. However, they possibly represent different species and were considered as such in Andersen et al. (2018).

• 

  Petiole and postpetiole in dorsal view of Epopostruma topendi: (a) holotype worker collected from Nitmiluk National Park; (b) paratype worker collected from Melville Island.

Description

Holotype worker. TL 3.9; HL 0.81; HW 0.75; CI 93; ML 0.43; MI 53; SL 0.49; SI 65; PW 0.51 AL 1.01. In full-face view the lateral margin of the head between the eye and the occipital lobe slightly angular. Posterior margin of head deeply concave, with occipital lobes somewhat angled posteriorly. Pronotal spines present, elongate. Posterior section of mesonotum in approximately the same plane as the dorsal face of propodeum, the junction of these plates forming a very shallow depression. Posterior face of propodeum with thin flanges between bases of spines and propodeal lobes. Petiolar node with a pair of conspicuous, semi-erect denticles on the dorsolateral margins. In dorsal view, petiolar node narrow and parallel-sided. Anterior face of the postpetiole distinctively flattened, with angular lateral margins. Sides of postpetiole not expanded laterally. In dorsal view, postpetiole bluntly square anterolaterally and conspicuously dentate posterolaterally, with denticles broader than long. Dorsum of petiole, postpetiole and gaster with numerous short, blunt and often clubbed erect hairs. Head, mesosoma, petiole and postpetiole with well-spaced foveolae and to a large extent smooth and shiny, especially dorsally. First gastral tergite entirely smooth. Colour uniformly reddish-brown.

References

• Andersen, A.N., Hoffmann, B.D., Oberprieler, S. 2018. Diversity and biogeography of a species-rich ant fauna of the Australian seasonal tropics. Insect Science 25, 519–526 (doi:10.1111/1744-7917.12402).
• Pettit, M.J., Andersen, A.N. 2021. A new species of Epopostruma (Hymenoptera: Formicidae) from monsoonal Australia. Zootaxa 5048, 141-144 (doi:10.11646/zootaxa.5048.1.9).
• Shattuck, S.O. 1999. Australian ants: their biology and identification. CSIRO Publishing, Collingwood, Victoria (doi:10.1071/9780643100671).
• Shattuck, S.O. 2000. The epopostrumiform genus group. In: Bolton, B., The ant tribe Dacetini. Memoirs of the American Entomological Institute, 65, pp. 30–67.
• Shattuck, S.O. 2007. New species of Myrmicine ants from Western Australia (Hymenoptera: Formicidae). Zootaxa 1661, 47–53.