Melophorus mullewaensis Heterick, Castalanelli & Shattuck

Heterick, Brian E., Castalanelli, Mark & Shattuck, Steve O., 2017, Revision of the ant genus Melophorus (Hymenoptera, Formicidae), ZooKeys 700, pp. 1-420 : 101-102

Melophorus mullewaensis Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker (top ant) from Mullewa, Western Australia, 15 September 1931 [collector unknown] [ANIC32-06621] (ANIC). Paratype: Minor worker on same pin and with same details as holotype (ANIC).

Diagnosis.

Melophorus mullewaensis is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus , the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. mullewaensis the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly). Only the (damaged) minor worker of Melophorus mullewaensis is known. This species can be distinguished from all others in its species-complex by its flattened, attenuated pronotum.

Minor worker description.

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20-0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex, frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly and evenly convex and protrusive; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile convex anteriad, mesonotum often slightly overlapping pronotum, mesosoma planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum matt or with a weak sheen and indistinctly shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its decliv ity greater than 2:1; erect propodeal setae always absent; appressed propodeal setulae long, each reaching setae behind and in front, but not forming pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length <0.50 × height of propodeum). Petiole. In profile, petiolar node rectangular, vertex blunt, directed posteriad; in full-face view, shape of petiolar node uniformly rounded; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster missing in two known specimens. General characters. Colour chocolate.

Measurements.

Worker (n = 2): CI 88; EI 25-28; EL 0.25-0.26; HL 1.05-1.18; HW 0.92-1.04; ML 1.91-2.01; MTL 1.13-1.21; PpH 0.17-0.14; PpL 0.80-0.87; SI 144 (one specimen); SL 1.49 (one specimen).

Comments.

This ant is known from a single pin of two damaged minor workers collected in the vicinity of Mullewa, Western Australia, very many years ago. These ants resemble the much more common Melophorus aeneovirens but are more gracile and the pronotum is more-or-less planar. Unfortunately the gaster of both specimens is missing. Nothing more is known about the species.

Etymology.

Named after the type locality; third declension masculine suffix added to toponym to form an adjective.