Melophorus propebiroi 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 : 191-193

Melophorus propebiroi Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker from Perth, Western Australia, 14 October 1976, J. D. Majer, P. trap RH10 A1089 [JDM32-001947] (WAM). Paratypes: minor worker from Murdoch 32°03'59"S, 115°51'07"E, Western Australia, August, 2011, C. Smithyman, control (S2/T2): remnant bushland adjacent to South Street Railway Station, Curtin University JDM Collection donated 13 Jan 2015 (WAM); minor worker from Bunbury, Western Australia, 20 December 1969, B.B. Lowery [ANIC32-900112] (ANIC).

Diagnosis.

Melophorus propebiroi can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. The species is placed in the M. biroi species-complex on the basis of a further suite of characters (viz, metatibia of major worker with only one preapical spur [except rarely in the mjobergi clade]; clypeal psammophore placed anteriorly at or just above anterior margin of clypeus in the minor worker and often in the major worker; head dorsoventrally compressed to varying degrees in the minor worker of most species with the eyes placed high on the sides; compact legs, and small body size [excluding mjobergi clade]; HW of smallest minor 0.36 mm, average HW of smallest minors 0.46 mm; HW of largest known major 1.29 mm, average HW of largest majors [where known] 1.05 mm). The minor worker of M. propebiroi closely resembles M. biroi but has relatively long, partially overlapping appressed setae that form a weak pubescence on the mesosoma and gaster and also numerous short, bristly, erect setae on the mesosoma and gaster. The pilosity pattern enables this species to be distinguished from all other taxa in its species-complex. Only the minor worker is known.

Minor worker description.

Head. Head square; posterior margin of head planar or weakly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only. 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, divergent posteriad; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly and evenly convex; 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 smoothly rounded anteriad, thereafter pronotum and whole of mesonotum flattened and on same plane as propodeum; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove a narrow but deep slit; propodeum shining and densely microreticulate, with distinct striolae on metapleuron; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity greater than 1:2; erect propodeal setae always absent; appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and longer (length ≥ 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node tapered with squared-off vertex; node shining and distinctly microreticulate. Gaster. Gaster shining with superficial microreticulation; pilosity of first gastral tergite consisting of well-spaced, short, thick, erect setae over long, closely aligned, whitish, appressed setae. General characters. Colour concolorous brown.

Measurements.

Worker (n = 2): CI 97-101; EI 24-25; EL 0.15-0.16; HL 0.64-0.67; HW 0.59-0.67; ML 0.82-0.91; MTL 0.44-0.51; PpH 0.10-0.10; PpL 0.37-0.41; SI 112-119; SL 0.70-0.76.

Comments.

As with M. latinotus , this species appears to be confined to woodland on the Swan Coastal Plain, WA, where it appears occasionally in collections. Apart from the material recorded here, this ant has also been taken in the Gingin area, near the Mitchell Freeway and at Bold Park. The major worker is unknown. Melophorus propebiroi looks very much like a hirsute M. biroi , and its weak pubescence, small eye and general pilosity enable it to be distinguished from other, similar species that occur with it in sympatry. No specimens were available for sequencing and nothing is known of its habits.

Etymology.

Latin prope ( ‘near’) plus biroi .