Polyrhachis decumbens
Polyrhachis decumbens | |
---|---|
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Hymenoptera |
Family: | Formicidae |
Subfamily: | Formicinae |
Tribe: | Camponotini |
Genus: | Polyrhachis |
Subgenus: | Cyrtomyrma |
Species: | P. decumbens |
Binomial name | |
Polyrhachis decumbens Kohout, 2006 |
Polyrhachis decumbens builds arboreal nests of silk and vegetation debris between the leaves of trees and shrubs. (Kohout 2006)
Identification
Similar to Polyrhachis nomo from New Guinea. Both share the characteristic pile of short, decumbent hairs covering most of the body. However, the pubescence in P. decumbens is abundant, while it is rather diluted in P. nomo. They differ in other aspects, including their relative size (HL 1.22-1.40 in P. decumbens versus 1.47-1.50 in P. nomo), and in the shape of their heads. In P. nomo the head is wider than long (CI 104-106) with the eyes not reaching the lateral cephalic outline in full face view. In P. decumbens the head is mostly longer than wide (CI 93-100) and the eyes clearly break the lateral cephalic outline. Both species feature rounded lateral pronotal margins, but several P. decumbens specimens from Iron Range have weakly indicated, blunt humeral angles and the pronotal dorsum is distinctly widest across the shoulders. Some of these specimens also feature more-or-less distinct, rudimentary propodeal spines or tubercles, that are completely absent in specimens of other populations of P. decumbens and in P. nomo. The spines of the petiole in P. decumbens are subequal, while in P. nomo the lateral petiolar spines are distinctly longer.
Keys including this Species
Distribution
Cape York Peninsula, north of the 13° parallel, extending to southern Papua New Guinea.
Latitudinal Distribution Pattern
Latitudinal Range: -10.76666667° to -10.76666667°.
North Temperate |
North Subtropical |
Tropical | South Subtropical |
South Temperate |
- Source: AntMaps
Distribution based on Regional Taxon Lists
Australasian Region: Australia (type locality).
Indo-Australian Region: New Guinea.
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. |
Estimated Abundance
Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species. |
Abundance
Relatively common in its favored rainforest habitats.
Biology
Castes
Males unknown, immature stages (eggs, larvae and pupae) in the Queensland Museum spirit collection. (Kohout 2006)
Nomenclature
The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.
- decumbens. Polyrhachis decumbens Kohout, 2006b: 96, figs. 1C, H-I (w.q.) AUSTRALIA.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Type Material
- Paratype, 4 workers, Lockerbie Scrub, Cape York Peninsula, Queensland, Australia, Australian National Insect Collection.
- Paratype, 2 workers, Lockerbie Scrub, Cape York Peninsula, Queensland, Australia, The Natural History Museum.
- Paratype, 2 workers, Lockerbie Scrub, Cape York Peninsula, Queensland, Australia, Museum of Comparative Zoology.
- Paratype, 2 workers, Lockerbie Scrub, Cape York Peninsula, Queensland, Australia, Musee d'Histoire Naturelle Genève.
- Paratype, worker, Lockerbie Scrub, Cape York Peninsula, Queensland, Australia, Queensland Museum.
- Paratype, 5 workers, 1 queen, Lockerbie Scrub, Cape York Peninsula, Queensland, Australia, Queensland Museum.
- Paratype, 2 workers, Lockerbie Scrub, Cape York Peninsula, Queensland, Australia, National Museum of Natural History.
Description
Worker
Dimensions (holotype cited first): TL c. 5.14, 4.79-5.49; HL 1.34, 1.22-1.40; HW 1.31, 1.17-1.40; CI 98, 93-100; SL 1.65, 1.50-1.78; SI 126, 121-130; PW 1.00, 0.87-1.03; MTL 1.65, 1.65-1.93 (23 measured).
Clypeus in profile straight; basal margin moderately impressed. Frontal triangle indistinct. Frontal carinae sinuate, margins very weakly raised anteriorly, rather flat posteriorly. Sides of head in front of eyes weakly convex; rounding behind eyes into convex occipital margin. Eyes convex, in full face view clearly breaking lateral cephalic outline. Ocelli lacking. Pronotum in dorsal view with humeri widely rounded; greatest pronotal width at or near mid-length of segment. Mesosomal dorsum in profile evenly convex; promesonotal suture distinct, metanotal groove lacking. Petiole with anterior face almost straight, posterior face weakly convex; dorsum armed with four subequal, acute spines. Subpetiolar process acute anteriorly, rounded posteriorly. Anterior face of first gastral segment straight, relatively low, narrowly rounding onto dorsum of segment.
Head, mesosoma and gaster shagreened, with intensity of sculpturation markedly increasing laterally, becoming distinctly wrinkled; sculpturation strongly reticulate-rugose on meso- and metapleurae and sides of petiole.
Several curved and suberect hairs on mandibular masticatory borders with shorter appressed hairs towards mandibular bases. Anterior clypeal margin with 1 long and 2 slightly shorter, anteriorly directed setae medially and several short setae fringing margin laterally. Mostly paired, medium length, erect hairs near anterior and basal margins of clypeus, along frontal carinae and on vertex; tuft of usually 4 erect, undulated, medium length hairs on summit of mesosoma. Gaster with numerous semierect hairs lining posterior margins of apical segments, more numerous on venter. Pubescence consisting of abundant very fine, short, decumbent and semierect hairs everywhere, including appendages, but excluding propodeal declivity that is smooth and shiny.
Colour. Black with mandibles, clypeus, sides of head and tibiae medium to dark reddish-brown, except mandibular masticatory borders and legs, including coxae, distinctly lighter. Dorsum of gaster black, posterior margins of segments diffusely lined with dark reddish-brown.
Queen
Dimensions (queen from nest of holotype cited first): TL c. 7.00, 7.26; HL 1.62, 1.72; HW 1.43, 1.59; CI 88, 92; SL 1.96, 2.06; SI 137, 129; PW 1.56, 1.68; MTL 2.46, 2.59 (2 measured). Apart from sexual characters, closely resembling worker except: pronotal humeri rounded; mesoscutum marginally wider than long with lateral margins converging anteriorly, forming relatively narrowly rounded anterior margin; median line bifurcate and weakly raised; parapsides flat anteriorly, slightly raised posteriorly; mesoscutum in profile with widely rounded anterior face and very weakly convex dorsum. Mesoscutellum only weakly convex, marginally elevated above dorsal plane of mesosoma. Metanotal groove distinct. Propodeum armed with distinct denticles; dorsum descending abruptly into virtually vertical declivity. Sculpturation, pilosity and colour virtually as in worker.
Type Material
HOLOTYPE: QUEENSLAND, Cape York Pen., Lockerbie Scrub, 10°46’S, 142°29’E, 19-23.iii.1987, ex nest between leaves, R.J. Kohout acc. 87.67 (worker). PARATYPES: data (and nest) as for holotype (15 workers, 1 dealate queen); data as for holotype, except RJK acc. 87.66 (4 workers). Holotype (QMT99334), 3 paratype workers and paratype queen (from holotype nest) and 2 paratype workers in Queensland Museum; 4 paratype workers (2 from holotype nest) in Australian National Insect Collection; 2 paratype workers (from holotype nest) each in The Natural History Museum, Museum of Comparative Zoology, Musee d'Histoire Naturelle Genève and National Museum of Natural History.
References
References based on Global Ant Biodiversity Informatics
- Janda M., G. D. Alpert, M. L. Borowiec, E. P. Economo, P. Klimes, E. Sarnat, and S. O. Shattuck. 2011. Cheklist of ants described and recorded from New Guinea and associated islands. Available on http://www.newguineants.org/. Accessed on 24th Feb. 2011.
- Kohout R.J. 2006. Review of Polyrhachis (Cyrtomyrma) Forel of Australia, Borneo, New Guinea and the Solomon Islands with descriptions of new species. Memoirs of the Queensland Museum 52: 87-146.