Melophorus gilliatensis 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 : 220-223

Melophorus gilliatensis Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker (top ant) from 3 miles ENE of Gilliat, Queensland, 15 April 1962, J. E. Dowse, A.307 [ANIC32-066645] (ANIC). Paratypes: 2 major workers on same pin and with same details as the holotype (ANIC); minor worker and 2 major workers from 3 miles ENE of Gilliat, Queensland, 15 April 1962, J. E. Dowse, A.307 [ANIC32-900059] (MCZ); minor worker from Ernest Henry Mine 20°28.0'S, 140°43.1'E, M. Sanders, site 1 (grassland A), pitfall 52010, native Atrebla grassland, Queensland Museum Loan Date: Nov. 2012 No. Ent 12.47 (QM).

Diagnosis.

Melophorus gilliatensis can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. The species is also placed in the M. fieldi species-complex because of the appearance of the anteriorly placed clypeal psammophore, the compact propodeum, the presence of more than one preapical spine on the metatibia, at least in the major worker, the long, even spindly legs and the unmodified mandible in the major worker. The clypeus is folded back abruptly slightly below its midpoint, so that the anterior portion projects as a protuberance at about 90° to the mandible, the clypeal psammophore being placed along the line of demarcation. The unusual form of the clypeus, suggestive of ants in the M. wheeleri complex, serves to identify the species, which is restricted to a small area of central QLD.

Minor worker description.

Head. Head square; posterior margin of head planar or weakly concave; frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of short, erect and semi-erect setae interspersed with shorter decumbent setae and well-spaced, short, appressed setae. 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 straight and retroussé anteromedially; clypeal psammophore set below midpoint of clypeus; 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 shining and microreticulate, microreticulation reduced on humeri; anterior mesosoma in profile broadly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and finely striolate and microreticulate; propodeum smoothly rounded or with indistinct angle, or angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 1:1 and 1:2; erect propodeal setae present and sparse to moderate (1-12); 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 squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and faintly striolate and microreticulate. Gaster. Gaster shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of a mixture of curved, erect and semi-erect setae and decumbent and appressed setae that form a variable pubescence. General characters. Colour of foreparts brown, gaster dark brown.

Major worker description.

Head. Head square tending to trapezoid anteriad; posterior margin of head weakly concave; cuticle of frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of many long, curved, semi-erect setae over well-spaced short semi-erect, decumbent and appressed setae. Eye moderate (eye length 0.20-0.49 length 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. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight in front of antennal insertion. Anterior clypeal margin broadly and evenly convex; clypeal psammophore set below midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining with very superficial microreticulation, entire lower mesopleuron distinctly shagreenate; anterior mesosoma in profile pronotum smoothly rounded anteriad and flattened posteriad, mesonotum narrowly convex; erect pronotal setae long (i.e., longer than length of eye) and unmodified; in profile, metanotal groove shallow, indicated mainly by an angle and metathoracic spiracles; propodeum shining and finely striolate and microreticulate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (at least a dozen); appressed propodeal setae long, each reaching setae behind and in front, but not forming pubescence; propodeal spiracle situated nearer to midpoint of propodeum than to its declivitous face, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly striolate and microreticulate. Gaster. Gaster shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of a mixture of curved, erect and semi- erect setae and decumbent setae that form a variable pubescence. General characters. Colour of foreparts very variable, including orange, black, or orange with brownish-red head; gaster dark brown to black.

Measurements.

Worker (n = 4): CI 103-120; EI 18-32; EL 0.28-0.30; HL 0.83-1.38; HW 0.85=1.66; ML 1.20-1.66; MTL 0.77-1.05; PpH 0.11-0.20; PpL 0.50-0.81; SI 64-113; SL 0.97-1.07.

Comments.

Material belonging to this species has been collected in just two almost contiguous localities (Gilliat and Ernest Henry Mine) in central QLD. The minor worker from Ernest Henry Mine was collected in a pitfall trap in Astrebla grassland. Nothing more is known of this rare and localized ant.

Etymology.

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