Myrmecia pilosula

Taylor, Robert W., 2015, Ants with Attitude: Australian Jack-jumpers of the Myrmecia pilosula species complex, with descriptions of four new species (Hymenoptera: Formicidae: Myrmeciinae), Zootaxa 3911 (4), pp. 493-520 : 496-497

The Myrmecia pilosula species complex

Diagnosis. Workers of the M. pilosula complex are easily recognized within Myrmecia (Ogata and Taylor, 1991). Relatively small species: total length, including mandibles, ranging overall from about 10 to 14 mm; mean size only slightly different in the separate species. Body color essentially uniformly dark blackish brown to black; mandibles, antennae, and frequently tarsi and/or tibiae reddish-orange; clypeus pale yellowish to light brown. Tip of apical antennomere flushed dark brown. Foreleg tarsi and tibiae in all known species prominently reddishorange; coxae, trochanters and femora always darkly colored, approximately matching body color; no transverse dorsal preoccipital carina; a ventral secondary tooth present near mandibular apex; mandibular dentition complete along length of jaw, all teeth essentially symmetrically erect, none inclined asymmetrically towards the mandibular base.

General morphology: General habitus as in the accompanying figures. Sculpturation generally similar among the species: mandibles smooth and shining, each dorsally with a few effaced apical longitudinal rugae. Head with longitudinal spaced striae separated by fine puncturation and effaced on the sides behind the eyes. Pronotum more strongly longitudinally striate than head, the nucal collar smooth to very finely transversely striate. Mesonotum similarly or more finely longitudinally striate than pronotum, varying to almost smooth, with a “leathery” appearance in several species due to superficial sculpturing, notably in both races of M. pilosula . Propodeal dorsum generally with a short anterior section bearing essentially longitudinal, often posteriorly divergent striate rugosity; the remainder transversely more strongly striate rugose. Petiolar dorsum ranging from almost smooth to quite strongly rugose, the intensity of sculpturation varying, but in most specimens approximately matching that of the mesonotum. In both races of M. pilosula the sculptural intensity in these areas varies allometrically and in concert. Postpetiole and gaster very finely and densely micropunctate, only moderately shining. The exposed anterior sections of the second and third gastral tergites (true abdominal segments 5 and 6), which each insert beneath the preceding tergite, minutely transversely striate and reflective.

Pilosity generally abundant on body and appendages, with the notable exception of M. haskinsorum (see key couplet 1 below); the hairs generally short and erect to suberect, longer and more flexuous on the underside and apex of the gaster, beneath the postpetiole and on the propleurae.

Pubescence generally very fine, often dense, varying in density and color interspecifically (generally either silvery grey or yellowish gold) as specified below in the species descriptions.

Human exposure

Urban Jack-jumpers are common in Hobart ( M. pilosula (Western Race)), Canberra ( M. croslandi , M. impaternata ) and Adelaide ( M. pilosula (Western Race)). They are less commonly represented in collections from Melbourne, with records of both races of M. pilosula and of M. croslandi , and poorly represented from Sydney, where there is only a single current record of M. banksi from Leumeah in the southeast of the city. There have been relatively few reports of Jack-jumper sting allergy from Sydney (B. Baldo, pers comm.) unlike Melbourne and especially Hobart, Adelaide and Canberra, so Jack-jumpers might not be well represented there. This was also the view of long-time Sydney resident Rev B.B. Lowery (pers comm.), who collected many Jack-jumper samples elsewhere (including all species recognized here). I have located few Melbourne urban records, but this is a possible artifact of inadequate collecting. Brisbane and Perth are, as far as known, outside the range of any species, though M. imaii is likely present in Perth.

In recreational bushland areas “Western” M. pilosula is common in the Adelaide Hills, the Grampians (VIC) and widely in Tasmania. The eastern race of M. pilosula is widespread in the NSW Snowy Mountains and associated ranges including the Victorian Alps, the Brindabella Ranges (ACT) and in the Blue Mountains west of Sydney.

Taxonomy of the primary JACP report and other papers

Imai, Taylor et al. (1994) and Crozier et al. (1995) recognized the species M. banksi , M. croslandi , M. haskinsorum and M. imaii precisely as defined here. The “scientific” names of these taxa, apart from M. croslandi , were then used prematurely (and with explanation) without the sanction of formal taxonomic publication. Nomenclature of these neglected species is rectified here, and this is their place of formal taxonomic publication. The name “ M. pilosula s. str. ” of the JACP publications was applied to the Western Race of that species as defined here. Other entities deemed speculatively in 1994 to represent hybrids between M. banksi (B) and M. pilosula (P) are assigned here to the Eastern Race of M. pilosula . These and the other “PB hybrids” of the above papers are allocated below as follows: (1) The Tasmanian P/PB–1 Mix and P/PB–2 Mix entities are assigned to the Western Race of M. pilosula ; (2) PBF1–1 and PBF1–2 are “synonymous” with M. impaternata ; and (3) PB–1 and PB–2 are identified as the Eastern Race of M. pilosula . Details are discussed in the following section and under the relevant species headings.