Melophorus fulvidus 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 : 218-220

Melophorus fulvidus Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker (top ant), from St George, Queensland, 14 January 1965 3.30 pm, B.B. Lowery, M. , R154, red soil, box pine scrub, 104°, foraging, very fast, (other side of label) nest a small dome [ANIC32-900119] (ANIC). Paratypes: Major worker, 2 media workers and 2 minor workers on same pine and with same details as holotype (ANIC); 2 minor workers from Manbulloo, SW of Katherine, Northern Territory, 7-11 April 1978, P.J. M. Greenslade, BB, 17) [ANIC32-900118] (MCZ).

Other material examined.

Queensland: ‘Gumbardo’ (Beutel, T.), ‘Merigol’ (Beutel, T.), St. George (Lowery, B.B. [ANIC32-900119]). Western Australia: 3 km E Fitzroy Crossing (Heterick, B.E. [M197]), Ethel Creek (Varris, P.A. [JDM32-004579]).

Diagnosis.

Melophorus fulvidus can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. This species is also placed in the M. fieldi species-complex because of the appearance of the anteriorly placed clypeal psammophore, the compact propodeum, the presence of more than one preapical spine on the metatibia, at least in the major worker, the long, even spindly legs and the unmodified mandible in the major worker. Melophorus fulvidus is a relatively distinctive species. The Major, media and minor workers are uniformly microreticulate and, in profile, the petiolar node of the minor and media worker is thick and tuberculate in shape, while that of the major worker is squamiform. The metatibial apical spur is absent in this species. The mesosoma of the minor and media workers is matt and glabrous, while that of the major worker has around 12 short, bristly, erect setae. These features, combined with the distinctive colour (minor and media workers are orange, the major worker orange with a brown gaster), will serve to identify the species.

Minor worker description.

Head. Head square; posterior margin of head planar or weakly 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 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 distinctly concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin straight; clypeal psammophore set at or above midpoint of clypeus; 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 matt or with weak sheen and microreticulate throughout; anterior mesosoma in profile broadly convex; appearance of erect pronotal setae long (i.e., longest erect setae longer than length of eye) and unmodified; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum matt or with a weak sheen and microreticulate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity about 4:3; erect propodeal setae always absent; appressed propodeal setulae sparse or absent, if present then not regularly spaced 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 cuboidal, rounded above; in full-face view, shape of petiolar node square with rounded angles; 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 concolorous dusky light orange.

Major worker description.

Head. Head square; posterior margin of head planar or weakly convex; cuticle of frons matt or with weak sheen, microreticulate; frons consisting mainly of appressed and stout erect setae, the latter bristly in appearance and distinctly modified (flattened) distally. Eye moderate (eye length 0.20-0.49 length 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. In full-face view, frontal carinae distinctly concave; frontal lobes straight in front of antennal insertion. Anterior clypeal margin broadly and evenly convex; clypeal psammophore set below midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker, or 4-5; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four, or absent; 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 broadly convex; erect pronotal setae short and often expanded distally, at times clavate; in profile, metanotal groove shallow, indicated mainly by an angle and metathoracic spiracles; propodeum matt or with a weak sheen and microreticulate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 1:1 and 1:2; erect propodeal setae present and sparse to moderate (1-12); appressed propodeal setae sparse or absent, if present then not regularly spaced; 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; node matt, and microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of thick, often distally flattened, erect setae over well-spaced, short, appressed setae. General characters. Colour of foreparts orange, gaster light orange-brown.

Measurements.

Worker (n = 6): CI 98-113; EI 26-37; EL 0.17-0.24; HL 0.47-0.83; HW 0.46-0.94; ML 0.68-1.14; MTL 0.46-0.66; PpH 0.08-0.12; PpL 0.30-0.50; SI 81-132; SL 0.61-0.77.

Comments.

Rather surprisingly, this species in TERC is placed by Andersen in his ' fulvihirtus ' group (as 'species 21'), despite its morphological similarity to similarly-coloured M. fieldi complex members. Limited sequencing (just one specimen) clearly places it within the M. fieldi complex. However, its closest relative remains uncertain. The uniform microreticulation of the cuticle, the yellowish-orange colour and the tuberculate nature of the node in minor and media workers are sufficient to characterize the species. Despite its relative rarity in collections the species is widespread, with samples from NT, QLD, and WA. Specimens from Gumbardo and Merigol Stations (QM) were collected in mulga habitat. In general, this ant has a northern distribution, with material from St George, Qld, constituting the most southerly record. The St George specimens were collected in box-pine scrub over red soil. The collector added the comment that the ant was foraging in 104°F and was 'very fast’.

Etymology.

Late-Latin fulvidus ('dull brownish-yellow’); adjective in the nominative singular.