Melophorus cerasinoniger 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 : 289-291

Melophorus cerasinoniger Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker (fifth ant from top) from Tailem Bend, South Australia, 26 January 1969, B.B. Lowery, limestone mallee [ANIC32-900136] (ANIC). Paratypes: 4 major workers and 2 minor workers on same pin and with same details as holotype (ANIC); 2 minor workers, minor worker and 2 major workers from Blyth, South Australia, 28 November 1957, B. Lowery, ' M. laticeps Wh.' [sic] (ANIC); 3 major workers from Big Desert, Victoria, 10 December 1979, A. N. Andersen, ' Melophorus ' (BMNH); 2 major workers from 7 km NW of Morgan, 16 December 1976, P.J. M. Greenslade, (6) (MCZ); media worker from Mundoora National Park, South Australia, 16 January 1975, P.J. M. Greenslade (SAM).

Other material examined.

New South Wales: Bogan River (Armstrong, J.), Callubri Station (Armstrong, J.). South Australia: Cambrai (Greenslade, P.J. M. ), Cambrai (Greenslade, P.J. M. ), Cambrai (Greenslade, P.J. M. ), Cambrai (Greenslade, P.J. M. ), Murray Bridge (Lea), Scorpion Springs CP, at northern entrance (Gross, G. F. [M85]), Waikerie (Greenslade, P.J. M. ).

Diagnosis.

Melophorus cerasinoniger can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. The species is also placed in the M. wheeleri species-complex because it agrees with the following apomorphies possessed by the complex: the minor worker often has more than five teeth, the largest major worker has a short, massive, elbowed mandible directed posteriad; in profile, the maxillary palps are short in the major and generally short in minor workers (in the minor worker, usually only attaining the neck sclerite at their maximum extent when the head is moderately inclined) and, in full-face view, the anterior margin of the clypeus in the large major worker is usually planar or weakly concave (variable in other subcastes but planar or narrowly protuberant anterior clypeal margins predominate). All workers of M. cerasinoger have a narrowly convex mesonotum, the pronotum being steeply (i.e., 60°>) inclined and flattened dorsally. Minor workers have a maximum of five mandibular teeth and in the major worker all teeth are on the same plane. This combination of characters, and in particular the conformation of the pronotum and mesonotum serves to distinguish the species.

Minor worker description.

Head. Head square; posterior margin of head weakly concave; frons shining and smooth except for piliferous pits; 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. Frontal carinae straight or weakly convex in full-face view, or straight, divergent posteriad; 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 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 shining and mainly smooth, vestigial shagreenation most noticeable on humeri and mesopleuron; anterior mesosoma in profile pronotum smoothly rounded anteriad and flattened posteriad, mesonotum narrowly convex; appearance of erect pronotal setae short and unmodified, or weakly expanded distally, or erect pronotal setae absent; in profile, metanotal groove deep, ‘V’ -shaped; propodeum shining and microreticulate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length <0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial sculpture. Gaster. Gaster shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly placed appressed setae. General characters. Colour of foreparts bright brownish-orange, gaster black or blackish-brown.

Major worker description.

Head. Head horizontally rectangular, broader than wide; posterior margin of head weakly concave; cuticle of frons shining and smooth except for piliferous pits; 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). Eyes 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 curved toward antennal insertion. Anterior clypeal margin straight, or broadly convex with anteromedial dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Mandibular teeth in major worker always 4; mandibles strongly incurved, apical sector weakly carinate or incompletely carinate; 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 shining and mainly smooth, vestigial shagreenation most noticeable on humeri and mesopleuron; anterior mesosoma in profile pronotum smoothly rounded anteriad and flattened posteriad, mesonotum narrowly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove deep, v-shaped; propodeum shining and shagreenate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae variable in number, may be absent; appressed propodeal setae short and closely aligned in sparse patches; 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 shining and smooth with vestigial microreticulation anteriad. Gaster. Gaster shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly spaced appressed setae. General characters. Colour of foreparts bright brownish-orange, gaster black or blackish-brown.

Measurements.

Worker (n = 6): CI 116-124; EI 13-18; EL 0.23-0.32; HL 1.09-1.95; HW 1.26-2.42; ML 1.37-2.00; MTL 0.91-1.29; PpH 0.15-0.21; PpL 0.54-0.74; SI 55-82; SL 1.03-1.33.

Comments.

Melophorus cerasinoniger is an aesthetically appealing species because of its bright, usually cherry-red foreparts and black gaster (thus the name chosen here for the ant). Along with the colour, the steeply convex pronotum and flattened posterior pronotum and anterior mesonotum serve to separate this taxon from related or similar species. No specimens of this exclusively eastern Australian ant, found in NSW, SA and Vic, were available for sequencing. Interestingly, all collections of M. cerasinoniger have been taken from the Murray-Darling drainage system, and thus the ecological requirements of the species may be associated with features of the habitat to be found along that system of rivers. Be that as it may, the only ecological records indicate the species has been collected from dunes at Cambrai and in limestone mallee in Tailem Bend, both in SA.

Etymology.

Latin cerasin ('of cherry’ [here, colour]) plus niger ( ‘black’); adjective in the nominative singular.