Melophorus rufoniger

One WA worker from Karonie was collected by sweeping, suggesting this species may forage on low vegetation. Given its typical appearance and its environmental adaptability, this species is likely a generalized scavenger. (Heterick et al. 2017)

Identification
Heterick et al. (2017) - Melophorus rufoniger is a member of the Melophorus aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in Melophorus nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In Melophorus rufoniger the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly). Melophorus rufoniger major and minor workers can be distinguished by their large size (HW > 1 mm in minor workers and > 3 mm in major workers), the asymmetrical vertex in the minor worker and the well-developed and protrusive clypeal flange in both major and minor workers. This species is also predominantly red-and-black compared with the shades of brown or yellow seen in similar species.

Melophorus rufoniger is on average larger than Melophorus praesens and lighter in colour, predominantly red or orange with a darker gaster. The clypeus is produced well beyond the base of the mandibles, and this feature and the asymmetrical head enable it to be distinguished from other members of its complex except for some morphologically very similar populations of reddish Melophorus curtus, in which case the pilosity of the hind femur must be closely examined. Despite its close physical resemblance to M. praesens, a three-gene tree places this species as sister to Melophorus sulconotus, a quite different-looking species with a distinctively plateau-like pronotum and mesonotum that descends abruptly to the propodeum. (Melophorus sulconotus was not successfully sequenced for the full five genes, so M. rufoniger and M. praesens appear as sisters on the five-gene tree, as might be expected from the morphology.)

Distribution
Heterick et al. (2017) - This species is widely distributed throughout Australia, although it avoids the wetter south-west corner of WA and similarly cool, moist habitats in SA and Vic.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Habitat
Melophorus rufoniger has been collected frequently in both red clay soil and yellow soil and also in a variety of vegetation zones. The latter include eucalyptus savanna, sclerophyll woodland, riparian woodland, mallee, Callitris woodland and Melaleuca woodland.

Nomenclature

 *  rufoniger. Melophorus rufoniger Heterick, Castalanelli & Shattuck, 2017: 122, fig. 19 (w.) AUSTRALIA.

Worker
Worker (n = 8): CI 87–109; EI 14–25; EL 0.28–0.47; HL 1.26–3.19; HW 1.10–3.46; ML 2.12–3.59; MTL 1.43–2.30; PpH 0.21–0.47; PpL 0.96–1.65; SI 69–158; SL 1.74–2.39.

Minor. Head. Head approximately oval, sides of head divergent towards mandibular articulations; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; frons shining with superficial shagreenation or microreticulation only; frons consisting almost completely of appressed setae that may form pubescence (tiny, erect setae, if present, usually confined to ocular triangle). 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, or distinctly concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; 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 moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove deep, ‘V’-shaped, or shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity greater than 2:1; erect propodeal setae always absent; appressed propodeal setulae minute and closely aligned, creating a silvery sheen; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node rectangular, vertex blunt, directed posteriad; in full-face view, shape of petiolar node uniformly rounded, or square with rounded angles; node shining and smooth with vestigial sculpture. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, long, whitish, appressed setae only, erect setae always absent. General characters. Colour of foreparts orange to reddish-tan, legs light tan, gaster chocolate.

Major. Head. Head quadrate (i.e., heart-shaped); posterior margin of head strongly concave; cuticle of frons shining and smooth except for piliferous pits, or shining with superficial shagreenation or microreticulation only; 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, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal midpoint notched; 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, but equivalent in length to remaining teeth; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt with indistinct shagreenate sculpture throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum matt or with a weak sheen and indistinctly shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae absent; appressed propodeal setae minute and closely aligned, creating a silvery sheen; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded, or generally rounded with median indentation, or square with rounded angles; node shining and faintly shagreenate-microreticulate. Gaster. Gaster 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 of foreparts reddish- or orange-brown, gaster brown to chocolate.

Type Material
Minor worker (bottom ant) from Koonamore, South Australia, 24-27 February 1973, P.J.M. Greenslade, pitfall traps [ANIC32-066663]. Paratypes: media and minor worker on same pin and with same data as holotype (ANIC); media and 2 minor workers from Katarapko island, South Australia, 29 April 1999, Loxton High, River Red Gum Pitfall [ANIC32-046417] (ANIC); 2 minor workers from Whiporie, 55 km s of Casino 29°15'S, 152°27'E, New South Wales, February 1997, SGO. 7-9, ‘Melophorus sp. 1 RTU 78 (ANIC); major and minor worker from Koonamore, South Australia, 24 February 1973, P.J.M. Greenslade, 1), [ANIC32-066641] ; major and minor worker from WNW Morgan, South Australia, 2 March 1975, P.J.M. Greenslade (leg. R. B. Halliday), (Nest 284) ; minor and 1 media worker from Cooloola, Noosa River, Queensland, 20 February 1977, P.J.M. Greenslade, (7) ; 2 minor workers from Reny Island 34°03'59"S, 140°42'41"E, South Australia, 6 November 1998, Renmark High, Black Box flight intercept [ANIC32-046592] . 2 minor workers from 15 km ESE Gympie 26°16'S, 152°48'E, Queensland, 2 January 1989, S. O. Shattuck,100m, #1244, Wet sclerophyll, random ground foragers, ANIC ANTS VIAL 77.109 [ANIC32-044509].

Etymology
Latin rufus plus niger (‘red-and-black’); adjective in the nominative singular.