Melophorus majeri

Known from a couple of records from heathland near the south coast of WA (Agosti 1997) and, more recently, from Eneabba. The one known nest was made directly into white sand. (Heterick 2009)

Identification
Heterick et al. (2017) - The armed propodeum in all worker sub-castes, the flattened and laterally carinate pronotum and mesonotum in the minor worker, the raised antennal lobes, and the absence of a metatibial apical spur distinguish Melophorus majeri from all other Melophorus and cause it to be placed in its own, unique species-group (Melophoprus majeri species-group).

This enigmatic species can be distinguished from all other Melophorus by reason of its armed propodeum in all worker subcastes. Other apomorphies include the absent metatibial apical spur (shared only with the unrelated Melophoprus anderseni group and Melophorus fulvidus) and the peculiarly flattened and carinate mesosoma in the minor worker, hence our tentative placement of M. majeri in its own species-group. The affinities of this ant are unknown, as no specimens were available for sequencing, but the appearance of the major worker suggests it may be close to the Melophoprus biroi species-group, if not a very aberrant member of that group.

Heterick (2009) - Minor workers of M. majeri are the only Melophorus with propodeal spines, and the dorsal and lateral surfaces of their flattened mesosomas are delimited by carinae. The minors also have very elongate heads and antennal scapes

Distribution
Known from southwestern WA.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Biology
Heterick et al. (2017) - The only known specimens (one nest series and a couple of strays) have come from white sand in southwestern WA. The minor worker, in particular, has more than a suggestion of being a mimic of a pselaphid beetle inquiline, with an extraordinary antennal scape that becomes incrassate distally and a flattened mesosoma. Could this be a kleptoparasite or subterranean nest raider of other ants? However that may be, minor workers are also active on the soil surface and have been collected as foragers. The nest series was associated with a piece of wood (Agosti 1997).

Nomenclature

 *  majeri. Melophorus majeri Agosti, 1998: 166, figs. 6-9 (s.w.) AUSTRALIA.

Worker
Heterick et al. (2017) - (n = 2): CI 70-102; EI 21-30; EL 0.14-0.19; HL 0.65-0.89; HW 0.46-0.91; ML 0.92-0.24; MTL 0.44-0.64; PpH 0.09-0.14; PpL 0.32-0.47; SI 96-223; SL 0.88-1.01

Minor. Head. Head elongate, truncate posteriad; posterior margin of head planar to 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 small (eye length less than 0.2 × length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set around midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight, elevated. Anteromedial clypeal margin narrowly convex and protruding, clypeal margin entire or very weakly indented; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six 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 matt or with weak sheen and microreticulate throughout; anterior mesosoma in profile gently undulate, dorsal and lateral surfaces separated by carinae; erect pronotal setae absent; in profile, metanotal groove a weak or vestigial furrow; propodeum matt or with a weak sheen and microreticulate; propodeum distinctly angulate, propodeal angles produced as short, erect denticles; length ratio of propodeal dorsum to its declivity about 3:2; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and longer (length ≥ 0.50 × height of propodeum). Petiole. In profile, petiolar node trapezoidal with sharply defined flange posteriad; in full-face view, shape of petiolar node tapered with squared-off vertex; node matt and microreticulate. Gaster. Gaster matt with distinct microreticulate pattern; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour blackish-brown.

Major. Head. Head square; posterior margin of head planar or weakly concave; cuticle of frons matt or with weak sheen, microreticulate; 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 small (eye length less than 0.2 × 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, elevated. Anterior clypeal margin convex, acuminate anteromedially, margin entire; clypeal psammophore set at or just above anterior clypeal margin; 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 matt or with weak sheen and microreticulate throughout; anterior mesosoma in profile gently sinuous after initial steep pronotal incline; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove a narrow but deep slit; propodeum matt or with a weak sheen and microreticulate; propodeum distinctly angulate, propodeal angles produced as short denticles; length ratio of propodeal dorsum to its declivity between 1:1 and 1:2; erect propodeal setae absent; appressed propodeal setae short, separated by more than own length and inconspicuous; 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 matt, and microreticulate. Gaster. Gaster matt with a distinct microreticulate pattern; pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly spaced appressed setae. General characters. Colour generally dark brown, head brown.

Type Material
Heterick et al. (2017) - Holotype minor and paratype major workers Hassel Road, Jerramungup, Western Australia. ,, (examined: ANIC holotype (second ant on pin of three workers) and paratypes CASENT0172019, CASENT017020, AntWeb images of AMNH (CASENT0104674) and CASC (CASENT0173922, CASENT0173922) specimens). The AntWeb Automontage image for the holotype erroneously depicts a paratype major worker from the same pin as the holotype. specimens, Note. Syntype label also erroneously displayed for CASENT0104674 (paratype).



References based on Global Ant Biodiversity Informatics

 * Agosti D. 1998. Two new enigmatic Melophorus species (Hymenoptera: Formicidae) from Australia. J. N. Y. Entomol. Soc. 105: 161-169.