Melophorus subulipalpus 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 : 142-144

Melophorus subulipalpus Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker from Tropicana Minesite 29°15'40"S, 124°35'50"E, Western Australia, January 2009, J. Summerhayes, pitfall tap, Casuarina , CA1:5 [JDM32-004701] (WAM). Paratypes: minor worker from Cambrai, South Australia, 24-28 February 1972, P.J. M. Greenslade, dune [ANIC32-900128] (ANIC); minor worker from 30 km ESE of Onslow 21°46'44"S, 115°22'01"E, Western Australia, 15 May 2006-29 August 2006, CALM Pilbara Survey, Site OYW12: ethylene glycol pitfalls [JDM32-004850] (WAM).

Other material examined.

Western Australia: Packsaddle (van Leeuwen, S.)

Diagnosis.

Melophorus subulipalpus is a member of the M. anderseni species-group (maxillary palp segments short [not reaching neck sclerite], narrow and terminating in a subulate [awl-shaped] segment; PF 6,4; metatibial apical spur absent; in full-face view, masticatory margin of mandible strongly oblique with four teeth in known major workers [except chrysus ], and four to six teeth in minor worker). The major worker of this species is unknown. The minor worker of M. subulipalpus can be distinguished from its sister species ( M. chrysus ) by having, in profile, the pronotum more-or-less flattened and only very weakly inclined anteriad, the head and body weakly to moderately shining, the sculpture ranging from superficial microreticulation to evident shagreenation or minutely striate sculpture, and in having, in profile, the clypeus strongly convex, tending to bulbous. The " pillipes " condition has not been not seen in the few workers collected.

Minor worker description.

Head. Head square; posterior margin of head strongly convex; frons shining and uniformly striolate, or 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, divergent posteriad; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin straight, or broadly and evenly convex; clypeal psammophore set below midpoint of clypeus; palp formula 6,4. Five or six mandibular teeth in minor worker; mandibles narrow, strap-like, internal and external margins parallel or nearly so; in five-toothed workers third mandibular tooth distinctly shorter than apical tooth and tooth no. two, tooth no. four vestigial; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining, uniformly striolate or superficially microreticulate; anterior mesosoma in profile weakly elevated anteriad, thereafter gently sinuate, pronotum and mesonotum on same plane; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum shining and uniformly striolate, or matt or with a weak sheen and microreticulate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between1:1 and 1:2; 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). Petiolar. In profile, petiolar node subcuboidal, vertex bluntly rounded; in full-face view, shape of petiolar node tapered with blunt vertex; node shining and distinctly shagreenate-microreticulate or superficially microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation, or shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour pale brownish-yellow to tan.

Measurements.

Worker (n = 4): CI 102-108; EI 26-30; EL 0.22-0.25; HL 0.70-0.93; HW 0.72-0.93; ML 1.15-1.53; MTL 0.97-1.29; PpH 0.12-0.15; PpL 0.49-0.63; SI 135-140; SL 1.01-1.26.

Comments.

Only four collections are known for this species, which can be distinguished from M. chrysus by its more matt appearance, less rounded pronotum and ochre colouration. The species occurs in WA and SA (at least). The sole South Australian specimen was collected from a dune, but otherwise nothing is known of the taxon.

Etymology.

Latin subulus ( ‘awl’) plus palpus ( ‘stroking’/‘caress’; applied to the palps of an arthropod); noun in the nominative singular standing in apposition to the generic name.