Melophorus macrops 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 : 177-179

Melophorus macrops Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker from Lake Mere field stn, New South Wales (label now missing, possibly mislaid during photographing), ' Melophorus sp. J’ [ANIC32-900105] (ANIC). Paratypes: 3 minor workers from Wilpena Pound, South Australia, 18 June 1972, B.B. Lowery (ANIC); minor worker from Cunnamulla, Queensland, 17 September 1974, P.J. M. Greenslade, (8), 16), [ANIC32-900101] (MCZ).

Diagnosis.

Melophorus macrops 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. macrops is defined at a species level by its large eye (EI 40-41), the presence of at least several erect setae on the mesosoma including propodeal setae, the deeply impressed metanotal groove (when viewed in profile) and the rounded propodeum. The first gastral tergite has erect setae, including a line of marginal setae. The major worker is unknown.

Minor worker description.

Head. Head approximately oval with straight sides; posterior margin of head weakly convex; frons shining and smooth except for piliferous pits; pilosity of frons a mixture of short, erect and semi-erect setae interspersed with shorter decumbent setae and well-spaced, short, appressed setae. Eye large (eye length ≥ 0.50 × length of side of head capsule), or moderate (eye length 0.20-0.49 length of side of head capsule); in full-face view, eyes set at about 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 curved toward 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 shining and smooth on dorsum, entire lower mesopleuron distinctly striolate-microreticulate; anterior mesosoma in profile weakly elevated anteriad, thereafter gently sinuate, pronotum and mesonotum on same plane; 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 smooth on dorsum and declivitous face, metapleuron with striolate-microreticulate sculpture; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and sparse to moderate (1-12); appressed propodeal setulae long and separated by at least own length; 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 smooth throughout. Gaster. Gaster smooth and glossy; pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly placed appressed setae. General characters. Colour of foreparts uniformly tan (or head dark chocolate, mesosoma tan), gaster dark chocolate.

Measurements.

Worker (n = 2): CI 92-95; EI 40-41; EL 0.18-0.19; HL 0.48-0.51; HW 0.45-0.47; ML 0.61-0.68; MTL 0.32-0.33; PpH 0.08-0.08; PpL 0.24-0.25; SI 109-110; SL 0.49-0.51.

Comments.

Melophorus macrops is here described from minor workers from Lake Mere Field Station, NSW, Cunnamulla, QLD and Wilpena Pound, SA, respectively. The only other material seen is a pin of three workers (a fourth point on the pin held a minor worker of Melophorus ludius -now removed) from Wilpena Pound, SA. This pin was inadvertently included among specimens of Melophorus sericothrix , so was not included in data collection. In appearance this ant is morphologically similar to M. biroi , but has at least a dozen erect setae on the mesosoma, and the eye is rather large (EI 40-41). The ant can also be distinguished from the smaller-eyed M. gracilis by the scalloped mesopleuron. The Lake Mere specimen was collected from a paddock. Apart from this, nothing more is known about M. macrops and no specimens were available for sequencing.

Etymology.

Greek makros ( ‘long’) plus ops ( ‘eye’); adjective in the nominative singular.