Melophorus nemophilus 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 : 130-134

Melophorus nemophilus Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype media worker (top ant) from 17 miles N of Colona HS, South Australia, 23 October 1960, McInnes & Dowse, Series A 336 [ANIC32-900077] (ANIC). Paratypes: 2 major workers on same pin and with same details as holotype (ANIC); 3 minor workers from 31.1 km S of Shearer’s Quarters 141°01'40"S, 34°50'30"E, Millewa South Bore Track, Murray Sunset National Park, Victoria, 14-23 November 2002, C. Lambkin, D. Yeates, N. Starwick & J. Recsei, 2m Sharkey malaise opening in closed mallee [ANIC32-043297] (ANIC); major worker, 2 media workers and a minor worker from 15 km WNW Yaapeet 32°42'S, 141°52'E, Victoria, 13 January 1980, 1500 hrs, A. N. Andersen, Melophorus (BMNH); 2 minor workers from Cambrai, South Australia, 4 February 1972, P.J. M. Greenslade, dune IIb (MCZ); minor worker from 10 km E Mt Ive HS, Gawler Ranges, South Australia, 21 October 1980, P.J. M. Greenslade, (1) (MCZ); minor worker from 10 km E Mt Ive HS, Gawler Ranges, South Australia, 22 October 1980, P.J. M. Greenslade, A2 Sa (SAM); media worker from Cambrai, South Australia, 20 January 1972, P.J. M. Greenslade, dune III (SAM); minor worker from Junana Rock 33.23S, 123.24E, 9 km NW of Mt Ragged, Western Australia, 26 October 1977, R.W. Taylor, 77.667 day strays (WAM).

Other material examined.

South Australia: Callanna Bore, Callanna Stn (Stony Desert survey), Cambrai (Greenslade, P.J. M. ), Cambrai (Greenslade, P.J. M. ), Cambrai (Greenslade, P.J. M. ), Ferries McDonald NP (Mathews, E. G [M116]), Keith, 5 km W Mt. Rough, Coorong (Greenslade, P.J. M. [ANIC32-900078]), near Mt. Westall (Taylor, R.W., Bartell, R.J. & Lowery, B.B.), Poochera (Taylor, R.W. & Bartell, R.J.), Scorpion Springs CP, 6.3 km S Pine Hut Soak (Forrest, J. [M91]), Wudinna townsite (Heterick, B.E. [M334]). Victoria: Little Desert Nat. Pk., Eastern Block, Dahlenburgs Mill Track, 17.8 km S Nhill (Lambkin, C., Yeates, D., Starwick, N. & Recsei, J. [ANIC32-030801]), Wyperfeld National Park, Murrayville Track, 45.2 km SSE Murrayville (Lambkin, C., Yeates, D., Starwick, N. & Recsei, J. [ANIC32-030935]). Western Australia: 28 mi SbyW Balladonia Motel (Taylor, R.W.); media worker from Junana Rock (Taylor, R.W.).

Diagnosis.

Melophorus nemophilus is a member of the M. 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 M. 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) but is placed in its own, monotypic species-complex. Uniquely for this group, the setae of the clypeal psammophore are fine and placed at around the midpoint of clypeus, and the anterior margin of the clypeus is a moderately flattened curve in all workers and does not cover the base of the mandibles. The ant has five to seven mandibular teeth, the major worker having the same mandibular structure as minor worker, and, in profile, the mesosoma is long and gracile, with an obliquely descending propodeum. Molecular data support the placement of M. nemophilus as belonging to a unique complex within the broader M. aeneovirens species-group.

Minor worker description.

Head. Head rectangular; posterior margin of head strongly convex; frons matt or with weak sheen, 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 around 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 broadly and evenly convex; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five to seven 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 convex anteriad, mesonotum often slightly overlapping pronotum, mesosoma planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae long and separated by at least own length; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length <0.50 × height of propodeum). Petiole. In profile, petiolar node subcuboidal, vertex bluntly rounded; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial sculpture. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour light brown to blackish, usually concolorous, but gaster may be darker.

Major worker description.

Head. Head square; posterior margin of head planar or weakly concave; cuticle of frons 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 moderate (eye length 0.20-0.49 length of head capsule); in full-face view, eyes set at midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anterior clypeal margin broadly and evenly convex; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six 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 moderately shining and shagreenate throughout; anterior mesosoma in profile convex anteriad, mesonotum overlapping pronotum, planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle and metathoracic spiracles; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae absent; appressed propodeal setae short, separated by more than own length and inconspicuous; 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 generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of foreparts orange or brownish-orange with dark brown gaster.

Measurements.

Worker (n = 8): CI 96-123; EI 17-30; EL 0.25-0.40; HL 0.86-1.94; HW 0.83-2.38; ML 1.65-2.77; MTL 1.25-1.83; PpH 0.16-0.33; PpL 0.72-1.18; SI 77-94; SL 0.78-1.83.

Comments.

This common, gracile species is intermediate in appearance between the M. bagoti complex and the M. aeneovirens complex. Limited sequencing data suggests the ant forms a monotypic complex basal to M. bagoti and M. gracilipes . Morphologically, this species is readily distinguished from others in the M. aeneovirens group by the high placement of the clypeal ammochaetae on the clypeus. Melophorus nemophilus is an arid or semi-arid resident of the southern states, and has been recorded from SA, Victoria and WA. The species may also occur in southwestern NSW, but is most probably absent from QLD and Tasmania. Most samples have been collected from remote areas in dunes, mallee woodland and spinifex and mallee woodland. The species most probably derives much of its nutriment from carrion, honeydew and nectar. A photograph by Ajay Narendra shows two minor workers carrying the corpse of a membracid bug while a major worker looks on (Fig. 6). Interestingly, this very gracile species can climb and forages on trees: the senior author of this paper has seen workers of M. nemophilus scurrying along smooth-trunked eucalypts near Norseman, WA, and workers have been taken in malaise traps in Little Desert N P, Murray Sunset N P and Wyperfeld N P in mid-western and northern Victoria.

Etymology.

Latin nemus ( ‘forest’) plus Neo-Latin philus ('attracted to’); noun in the nominative singular standing in apposition to the generic name.