| Polyrhachis sexspinosa|
Polyrhachis sexspinosa is a relatively common and widespread species reported from most of the New Guinean mainland and islands of eastern Indonesia, including several doubtful records from the southern Philippines (Kohout, 1989). In Australia it ranges from Lockerbie Scrub south to Rocky River, northeast of Coen. Polyrhachis sexspinosa is somewhat singular within the sexspinosa-group in that it builds pocket-like nests of silk, vegetation debris and bark fragments against the trunks of rainforest trees (see images below).
A member of the Polyrhachis sexspinosa species group.
Kohout (2010) - Polyrhachis sexspinosa resembles Polyrhachis reclinata, with their main distinguishing characters given in remarks section under the latter species.
Keys including this Species
Distribution based on Regional Taxon Lists
Distribution based on specimens
Males and immature stages (eggs, larvae in various stages of development and pupae) in QM spirit collection.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- sexspinosa. Formica sexspinosa Latreille, 1802c: 126, pl. 4, fig. 21 (w.) INDONESIA ("Indes orientales"). Mayr, 1867a: 42 (q.); Karavaiev, 1927e: 26 (m.). Combination in Polyrhachis: Smith, F. 1858b: 59; in P. (Myrmhopla): Viehmeyer, 1916a: 167. Senior synonym of argentata: Lepeletier de Saint-Fargeau, 1835: 219; of irritabilis: Roger, 1863b: 6; of sericea: Bolton, 1975c: 12; of barnardi: Kohout & Taylor, 1990: 519. See also: Kohout, 2010: 196.
- argentata. Formica argentata Fabricius, 1804: 413 (w.) NEW CALEDONIA. Combination in Polyrhachis: Smith, F. 1858b: 73. Junior synonym of sexspinosa: Lepeletier, 1835: 219; Roger, 1863b: 6.
- irritabilis. Polyrhachis irritabilis Smith, F. 1859a: 141 (q.) INDONESIA (Aru I.). Junior synonym of sexspinosa: Roger, 1863b: 6.
- sericea. Polyrhachis (Myrmhopla) sexspinosa var. sericea Karavaiev, 1927e: 26, fig. 13 (w.q.m.) INDONESIA (Aru I.). [Also described as new by Karavaiev, 1928: 316.] Junior synonym of sexspinosa: Bolton, 1975c: 12.
- barnardi. Polyrhachis (Myrmhopla) barnardi Clark, 1928a: 39, pl. 1, figs. 37, 38 (w.) AUSTRALIA. Clark, 1930c: 14 (q.). Junior synonym of sexspinosa: Kohout & Taylor, 1990: 519. See also: Bolton, 1975c: 6.
- Formica sexspinosa Latreille, 1802: Neotype (designated by Kohout (2010)), worker, West Sepik Prov., Pes Mission, 12 km SW of Aitape, < 50m, Papua New Guinea, Australian National Insect Collection; rainforest. , 3 August 1984, RJK acc. 84.207,
- Polyrhachis (Myrmhopla) barnardi Clark, 1928: Syntype, worker(s), Cape York, Queensland, Australia, Australian National Insect Collection.
- Polyrhachis (Myrmhopla) barnardi Clark, 1928: Syntype, 1 worker, Cape York, Queensland, Australia, Museum of Comparative Zoology.
- Polyrhachis (Myrmhopla) barnardi Clark, 1928: Syntype, worker(s), Cape York, Queensland, Australia, Museum Victoria, Melbourne.
Polyrhachis sexspinosa was originally described from a queen collected in the ‘East Indies’. The holotype queen of this species should be lodged in the Musee National d'Histoire Naturelle, but an extensive search by the author failed locate it there or in any collections examined and it is considered lost. I support the earlier decision of Kohout & Taylor (1990: 518-520) who recognised the specimens of a nest series from Papua New Guinea (see above) as the voucher specimens of P. sexspinosa by designating one of these workers as the neotype for this name (ANIC, QM). A worker specimen was designated as the neotype of Polyrhachis sexspinosa (Latreille) from this colony of 50+ workers, a dealate queen and several males collected from a pocket nest on the trunk of a rainforest tree. The neotype has been deposited in ANIC.
The following notes on V.A. Karavaiev type specimens have been provided by Martynov & Radchenko (2016) based on material held in the Institute of Zoology, Ukrainian Academy of Science:
Polyrhachis (Myrmhopla) sexspinosa Latr. var. sericea Karawajew, 1927.
Type locality(-ies): “Wammar, Aru, 24.III.1913 (Nr. 2642), ww, geflüg. qq und mm in einem Nest gesammelt”.
Original Karawajew label(-s): “Polyrhachis (Myrmhopla) / sexspinosa Latr. v. sericea / Karav. typus. / Wammar, Aru, 2597, 2642, Leg. / et det. V. Karavaev”.
Material: SYNTYPES, 6 w, 1 q (newly mounted, IN 314/6/2), 27 w (in alcohol, IN 314/BAMS1/Karaw11–13).
Notes. Karawajew (1927a) provided in the original description collection number 2462 for the type series of this taxon, while in the single vial with alcohol material in NMNH NASU there are original Karawajew labels with collection numbers 2642 and 2597. We investigated all workers from this vial and confirm their conspecificity. Moreover, among the mounted specimens of var. sericea from SIZK there are syntypes series with number 2462, and one worker labeled as “Wamman, Aru. 2671. Karawajew”, “Polyrhachis (Myrmhopla) sexspinosa Latr. v. sericea Karaw. typus” that also does not correspond to the collection number given in the original description. We may only suppose that Karawajew did not provide all the collection numbers when describing this taxon, and we consider all the material from NMNH NASU as syntypes.
Holotype worker in Oxford University Museum of Natural History. Labelled “Aroo” (= Aru I., New Guinea) and with a Donisthorpe type-label.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Kohout (2010) - TL c. 12.60-14.76; HL 3.12-3.58; HW 1.84-2.17; CI 57-62; SL 3.78-4.48; SI 195-216; PW 1.81-2.03; MTL 4.79-5.74 (27 measured).
Anterior clypeal margin arcuate, often with very shallow median emargination. Clypeus with median carina, virtually straight in profile, posteriorly curving into moderately impressed basal margin. Frontal carinae sinuate with acute, highly raised margins. Sides of head in front of eyes almost straight, weakly diverging towards mandibular bases; behind eyes sides strongly tapered into narrow occipital margin with strongly developed occipital lobes. Eyes strongly convex, in full face view clearly exceeding lateral cephalic outline. Ocelli lacking, positions indicated by distinctly raised cephalic sculpture. Pronotal dorsum convex in profile, distinctly higher than mesonotum; humeri armed with strong, acute, more-or-less horizontal, anterolaterally directed spines; promesonotal suture distinct. Mesopleural process a distinct, dentiform lobe. Mesonotum and propodeum weakly convex in profile. Propodeal spines relatively long, virtually straight, in lateral view usually vertical to main axis of body or inclined forwards, tips sometimes curved posteriorly or inwards. Dorsum of petiole with a pair of lateral, dorsoposteriorly directed, acute spines.
Mandibles with numerous piliferous pits. Clypeus and sides of head finely reticulate-punctate with intensity and density of sculpturation distinctly increasing posteriorly, vertex and occiput rather coarsely sculptured. Mesosomal dorsum rugose with intensity decreasing posteriorly with propodeal dorsum finely reticulate-punctate. Gaster very finely shagreened.
Mostly silvery or grey, erect or variously curved hairs of variable lengths and densities over the entire body and appendages, including antennal scapes. Longest hairs on mesosomal dorsum, clearly longer than greatest diameter of eye. Head and mesosoma with somewhat untidy, relatively long, mostly silvery, suberect pubescence that never completely hides underlying sculpturation; most dense and more appressed on dorsum of head and mesosoma, somewhat radiating on sides. Gastral pubescence ranging from diluted on venter to dense on dorsum, where it is arranged in characteristic midline pattern.
Body black; mandibles, except bases, apical antennal segments and legs, including coxae, mostly light to medium reddish-brown.
Kohout (2010) - TL c. 13.46-16.28; HL 3.17-3.78; HW 1.86-2.37; CI 57-63; SL 3.73-4.59; SI 189-211; PW 2.02-2.82; MTL 4.74-5.64 (11 measured).
Queen very similar to worker; apart from usual characters identifying full sexuality, including three ocelli, complete thoracic structure and wings differing mainly in configuration of spines; pronotal spines shorter, projecting more anteriorly, tips directed forwards; propodeal spines distinctly shorter, oblique to main axis of body, weakly curved posteriorly; petiolar spines straight, distinctly shorter than in worker; sculpturation, pilosity and colour pattern identical to worker.
- Baltazar, C. R. 1966. A catalogue of Philippine Hymenoptera (with a bibliography, 1758-1963). Pac. Insects Monogr. 8: 1-488 (page 284, listed)
- Bolton, B. 1975c. The sexspinosa-group of the ant genus Polyrhachis F. Smith (Hym. Formicidae). J. Entomol. Ser. B 44: 1-14 (page 12, Senior synonym of sericea)
- Clark, J. 1928a. Australian Formicidae. J. R. Soc. West. Aust. 14: 29-41
- Karavaiev, V. 1927f. Ameisen aus dem Indo-Australischen Gebiet. III. Zb. Prats Zool. Muz. 3:3-52 [= Tr. Ukr. Akad. Nauk Fiz.-Mat. Vidd. 7:3-52]. (page 26, male described)
- Kohout, R.J. 2010. A review of the Australian Polyrhachis ants of the subgenera Myrmhopla Forel and Hirtomyrma subgen. nov. Memoirs of the Queensland Museum – Nature. 55:167-204. PDF
- Kohout, R. J.; Taylor, R. W. 1990. Notes on Australian ants of the genus Polyrhachis Fr. Smith, with a synonymic list of the species (Hymenoptera: Formicidae: Formicinae). Mem. Qld. Mus. 28: 509-522 (page 519, Senior synonym of barnardi)
- Latreille, P. A. 1802b. Histoire naturelle générale et particulière des Crustacés et des insectes. Tome 3. Familles naturelles des genres. Paris: F. Dufart, xii + 467 pp. (page 126, pl. 4, fig. 21 worker described)
- Lepeletier de Saint-Fargeau, A. 1835 . Histoire naturelle des insectes. Hyménoptères. Tome I. Paris: Roret, 547 pp. (page 219, Senior synonym of argentata)
- Martynov, A.V., Radchenko, A.G. 2016. Karawajew's ant type specimens (Hymenoptera, Formicidae) in the National Museum of Natural History of the National Academy of Sciences of Ukraine. Zootaxa 4097 (2): 244–254.
- Mayr, G. 1867a. Adnotationes in monographiam formicidarum Indo-Neerlandicarum. Tijdschr. Entomol. 10: 33-117 (page 42, queen described)
- Robson, S.K.A. & Crozier, R. 2009. An evaluation of two biochemical methods of age determination in insects (pteridines and lipofuscins) using the ant Polyrhachis sexpinosa Latrielle (Hymenoptera: Formicidae). Australian Journal of Entomology 48, 102-106
- Roger, J. 1863b. Verzeichniss der Formiciden-Gattungen und Arten. Berl. Entomol. Z. 7(B Beilage: 1-65 (page 6, Senior synonym of irritabilis)
- Smith, F. 1858a. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp. (page 59, Combination in Polyrhachis)
- Viehmeyer, H. 1916a . Ameisen von Singapore. Beobachtet und gesammelt von H. Overbeck. Arch. Naturgesch. (A) 81(8): 108-168 (page 167, Combination in P. (Myrmhopla))