Chelaner nightcapensis

This ant is one of several species in the C. rubriceps species-complex that are known from one or a few collections only. This ant, like others in the species-complex, nests in wood. (Heterick 2001)

Identification
Heterick (2001) - A member of the rubriceps group. The appearance of C. nightcapense is very similar to that of Chelaner rubriceps, but the eye is large and the alitrunk is smooth and bare of sculpture.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  nightcapense. Monomorium nightcapense Heterick, 2001: 433, fig. 42 (w.) AUSTRALIA.
 * Combination in Chelaner: Sparks et al., 2019: 233.

Worker
Holotype. HML 3.10; HL 1.08; HW 0.98; CeI 90; SL 0.92; SI 94; PW 0.64. Others. HML 2.92-3.23; HL 0.98-1.08; HW 0.88-0.98; CeI 88-91; SL 0.81-0.91; SI 93-96; PW 0.55-0.61 (7 measured).

As for the worker of Chelaner rubriceps, but with the following apomorphies.

Head. Head square or rectangular; vertex planar; frons smooth and shining with combination of incurved decumbent and subdecumbent setulae and erect and suberect setae. Compound eyes circular or subcircular, or elliptical; eye large, eye width greater than 1.5x greatest width of antennal scape. Anteromedial clypeal margin straight or slightly emarginate, median clypeal carinae not produced as teeth or denticles. Mandibles (viewed from front) triangular and smooth, with piliferous punctures.

Alitrunk. Promesonotal sculpture absent, promesonotum smooth and shining; setulae decumbent and subdecumbent. Metanotal groove present as feebly impressed furrow between promesonotum and propodeum. Propodeal sculpture absent; propodeum smooth and shining; dorsal propodeal face flattened; processes absent (propodeum smoothly rounded in profile or with slight hump at propodeal angle). Declivitous face of propodeum flat. Erect and suberect propodeal setae > 5.

Petiole and postpetiole. Petiolar node tumular and inclined posteriad. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 1: 1. Anteroventral process always absent or vestigial. Height-length ratio of postpetiole near 4:3 to near 1:1. Ventral process vestigial.

General characters. Colour of most of head capsule brown, mandibles and surrounding part of head, alitrunk, petiole, postpetiole, and appendages amber, anterior sector of first gastral tergite yellow, remainder of gaster dark brown. Worker caste monomorphic.

Type Material
Holotype. Worker (top point), New South Wales, Blue Knob, Mt Nightcap Ra., 5.ix.l966, B. B. Lowery, rainforest, 3000 ft., ANIC ants vial 1.147. Paratypes. New South Wales: 2 + 3 workers with same data as the holotype (ANIC, ); 5 workers and 1 ergatoid, same collection details as holotype, additional data: “in centre of large moss-covered branch, A211” [ants on this pin wrongly identified as M. kilianii].



Etymology
Named after the Nightcap Ranges.