Prionopelta robynmae, Shattuck, S. O., 2008

Shattuck, S. O., 2008, Revision of the ant genus Prionopelta (Hymenoptera: Formicidae) in the Indo-Pacific region., Zootaxa 1846, pp. 21-34 : 30-32

Prionopelta robynmae sp. n.

(Figs 6-7, 17-19, 23)

Types. Holotype worker from 1.5km EbyN Mt. Sorrow, 16°05'S 145°27'E, Queensland, A. Calder & T. Weir, 25 March 1984, litter sample, rainforest on stony slope ( ANIC, ANIC 32-039009). Eight paratype workers, same data as holotype ( ANIC, MCZC, BMNH, ANIC 32-031327).

Diagnosis. Anterolateral corners of head, near mandibular insertions, rounded. Pronotal sculpturing consisting of small, closely spaced foveae which contrast markedly with the widely spaced foveae on mesonotum and propodeum, the foveae on the propodeum varying strongly in density across its width (weakest medially, stronger laterally). Body small, head width less than 0.48mm but petiole relatively broad, PetW greater than 0.22mm;

Description. Anterolateral corners of head, near mandibular insertions, rounded and lacking a tooth. Dorsal pronotal sculpturing consisting of small closely spaced foveae which contrast markedly with the widely spaced foveae on the mesonotum and propodeum. Foveae on dorsum of propodeum varying across its width (weakest medially, stronger laterally). Lateral mesosomal sculpturing consisting of small, widely spaced foveae on pronotum and anterior region of mesopleuron, ventral regions of mesopleuron and propodeum weakly striate, posterodorsal region of mesopleuron and majority of propodeum smooth. Fenestra present within subpetiolar process. Colour pale yellow to yellow-red, queens generally slightly darker.

Measurements. (n=19) CI 72-78; HL 0.46-0.63; HW 0.35-0.47; ML 0.56-0.73; PetL 0.15-0.19; PetW 0.22-0.28; PI 131-165; SI 64-73; SL 0.24-0.34; T 1W 0.32-0.41.

Material examined (in ANIC unless otherwise noted). Australia: New South Wales: 20km E Legume (Greenslade,P.J.M.); Bruxner Park, Coffs Harbour (Lowery,B.B.; Monteith,G.); Cedar Creek, Mt. Warning (Lowery,B.B.); Dorrigo Nat. Park (Hill,L.); Gerroa (Lowery,B.B.); Mt. Warning (Lowery,B.B.); Sandy Creek, Bonalbo (Kearney,E.G.); The Bird Tree, Middle Brother State Forest, nr. Kendall (Harvey,M.S. & Rentz,D.C.F.); Wiangaree S.F. Sheepstation Ck. (Newton,A. & Thayer,M.) ( MCZC); Northern Territory: Radon Ck., Kakadu Area (Kikkawa,J.); Sawcut Gorge (Taylor,R.W. & Feehan,J.E.); Queensland: 1.5km EbyN Mt. Sorrow (Calder,A. & Weir,T.); 14km SW Yarraman (Hill,L.); 2.5km W Cape Tribulation (Site 5) (Monteith, Yeates & Thompson); 2km N by E Mt. TipTree (Calder,A. & Weir,T.); 4.5 km W of Cape Tribulation(Site 9) (Monteith, Yeates & Thompson; Monteith,G.B. & Yeates,D.K.); 4km W of Cape Tribulation (site 8) (Monteith, Yeates & Thompson); 5km E Yarraman (Hill,L.); 6km E Butchers Creek School (Monteith,G.); 6km SSW North Tamborine (Ward,P.S.); 7km NNW North Tamborine (Ward,P.S.); Alexandra Bay (Taylor,R.W.); Bakers Blue Mt., 17km W Mount Molloy (Monteith,G.B. & Cook,D.); Bellenden Ker Range, 1km S Cable Tower 6 (Earthwatch, Qld Museum); Binna Burra (Woodward,T.E.); Biolela (Andersen,A.N) (TERC); Boar Pocket Rd., N Gillies Highway (Brooks,J.G.); Burpengary Creek (Woodward,T.E.); Burwilla, Cooloola Natl. Pk. (Greenslade,P.J.M.); c. 3km S of Eungella (Taylor,R.W.); Cape Tribulation (Monteith,G.B.); Cannon Vale (Monteith,G.); Cooloola Natl. Pk., Kabali W (Greenslade,P.J.M.); Cooloola, Chalambar(Greenslade,P.J.M.); Cooloola, Kabali E (Greenslade,P.J.M.); Cunninghams Gap (Lowery,B.B.); Danbulla Forestry Reserve (Holt,J.); Elliot Range v. Townsville (Darlington,P.F.); Kroombit Tops, 45km SSW Calliope, Site 14 (Monteith, Davies, Gallon & Thompson); Kroombit Tops, 45km SSW Calliope, Site 4 (Monteith, Davies, Gallon & Thompson); Kroombit Tops, 45km SSW Calliope, Site 8 (Monteith, Davies, Gallon & Thompson); Kroombit Tops, 65km SW Gladstone (Monteith,G.B. & Thompson,G.); L. Eacham Nat. Pk (Taylor,R.W.); Landsborough (Taylor,R.W.); Lockerbie, Cape York Pen. (Sedlacek,J.); Lower Ballunji Falls, Palm Grove, Lamington Nat. Pk (Woodward,T.E.); Malanda Falls Environmental Park (Cutter,A.D.); Mt. Bartle Frere (Darlingtons); Mt. Chinghee, 12km SE Rathdowney (Monteith, Yeates & Thompson); Mt. Father Clancy, 10km S Millaa Millaa (Monteith,G.B. & Yeates,D.K.); Mt. Hypipamee NP (Monteith,G.); Mt. Webb Nat. Pk (Cardale,J.C.; Calder,A. & Feehan,J.); Mulgrave River Road, 7km WbyS Bellenden Ker (Calder,A. & Weir,T.); Noah Creek, 7km ENE Thornton Peak (Calder,A. & Weir,T.); Noah Creek, Cape Tribulation (Moneith,G.B.); Nob Creek, Byfield (Monteith,G.B.); road summit on Alexandra Ra., Daintree (Monteith, G.); Shiptons Flat (Naumann,I.D.); slopes below Wilsons Peak, Border [NSW and QLD] (Woodward,T.E.); Tambourine Mt. (E Side below Eagle Point) (Woodward,T.E.); Tambourine Mt. (N Side nr. Curtis Falls) (Woodward,T.E.); Tamborine Mt., Queensland National Park 793 (Curtis,H.S.); Upper Tallebudgera Ck., below Springbrook (Monteith & Thompson); Wacol, Brisbane (Lowery,B.B.); Wallaman Falls, via Ingham (Monteith,G.); Warrawonga, Cooloola Natl Pk (Greenslade,P.J.M.); Yungaburra State Forest (Gush,T.); Victoria: The Grampians (McAreavey,J.). Western Australia: near Boddington (Postle,A.). Papua New Guinea: Madang: Wau, Kunai Creek (Taylor,R.W.); Morobe: 24km NW Wau (Anderson,R.S.) ( CASC).

Comments. Specimens here placed in P. robynmae were previously considered to belong to P. kraepelini and/or P. opaca (see Introduction for details). However, the above diagnosis will separate these specimens from others in the genus and suggest that they belong to a distinct species. This species shows only slight and minimal variation in overall colour (from light to dark yellow-brown) and sculpturing (in the density of punctations on the head and dorsal mesosoma). Additionally, no geographic pattern is apparent in this variation and it seems to be randomly distributed geographically. However, the species does show considerable variation in body size. For example, numerous workers from Mt. Bartle Frere, Queensland, are consistently larger than any other known specimens while specimens from Mt. Webb Nat. Pk, Queensland, are distinctly smaller than (Fig. 7). But while these specimens differ in size they are essentially identical in all other characters to more typical specimens placed in this taxon with no indication that they represent a separate species.

P. robynmae is most similar to P. kraepelini but differs in having small foveae on the pronotum rather than small punctures, stronger variation in the density of sculpturing across the width of the propodeum, in having a broader petiolar node (width greater than 0.22mm versus less than 0.21mm in kraepelini, Fig . 6) and in having a relatively longer and narrower head (although the smallest robynmae workers are essentially identical to similarly sized kraepelini workers) (Fig. 7). See Comments under P. kraepelini for further details.

Geographically this species is exceptionally widespread for a member of this genus, occurring from PNG in the north to Victoria and Western Australia in the south. It also shows considerable ecological variability with specimens being found in a range of forested habitats including rainforests, open forests, paperbark swamps and Picabean palm forests. Foraging workers occur in leaf litter while nests have been found in soil under objects, between rock slices and in rotten wood.