Chelaner brachythrix

The species is known from a few workers only, all taken from coastal woodland and sand-plain heath north of Perth.

Identification
Heterick (2001) - This small member of the rubriceps group resembles a species of Solenopsis, but can be distinguished from members of that genus by its 3-segmented antennal club and larger eye. A Burakin specimen has a narrower petiolar node than the other workers, and in this respect approaches Chelaner leae (i.e. the “flavipes-insularis” and “leae” morphs).

Heterick (2009) - The workers are covered in very short, erect setae.

Distribution
Heterick (2009) - WA. Appears to be confined to the sand- plains north and north-east of Perth.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  brachythrix. Monomorium brachythrix Heterick, 2001: 420, figs. 44, 76, 85 (w.) AUSTRALIA.
 * Combination in Chelaner: Sparks et al., 2019: 232.

Worker
Holotype. HML 1.59; HL 0.55; HW 0.46; Cei 83; SL 0.37; SI 80; PW 0.32. Others. HML 1.34-1.79; HL 0.50-0.61; HW 0.40-0.49; CeI 77-88; SL 0.34-0.42; SI 76-85; PW 0.32-0.34 (7 measured).

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

Head. Head square or rectangular; vertex slightly concave; frons smooth and shining with incurved decumbent and subdecumbent setulae. Compound eyes elliptical; (viewed from front) compound eyes set in anterior half of head capsule; (viewed laterally) compound eyes set at midline of head capsule. Posteromedial clypeal margin extending slightly posteriad of posterior surface of antennal fossae. Anterior tentorial pits situated nearer antennal fossae than mandibular insertions. Frontal lobes parallel, sinuate. Palp formula unknown.

Alitrunk. Dorsal promesonotal face convex anteriad, otherwise flattened. Metanotal groove present as distinct and deeply impressed trough between promesonotum and propodeum. Propodeal sculpture present as faint microreticulation with few striae, mainly on lower lateral surface; dorsal propodeal face gently convex, or sloping posteriad, with wedge-shaped flattening or shallow depression that is widest between propodeal angles; processes absent (propodeum smoothly rounded in profile or with slight hump at propodeal angle. Propodeal angle absent; declivitous face of propodeum flat. Erect and suberect propodeal setae greater than 10; propodeal setulae decumbent and subdecumbent.

Petiole and postpetiole. Petiolar spiracle lateral and in anterior sector of petiolar node. Petiolar node tumular and inclined posteriad; sculpture absent, petiolar node smooth and shining. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 4:3 to near 1: 1. Anteroventral process always absent or vestigial. Height ratio of petiole to postpetiole near 1:1 to near 4:3; height-length ratio of postpetiole near 4:3 to near 1:1. Sculpture absent on dorsum, at least: postpetiole smooth and shining. Ventral process absent or vestigial, or present and distinct.

Gaster. Pilosity of first gastral tergite consisting entirely of well-spaced erect and suberect setae.

General characters. Colour fulvous. Worker caste monomorphic.

Type Material
Holotype. Worker, Western Australia, Eneabba, ix.1975, J. Fox, pitfall trap A290, JDM 163. Paratypes. Western Australia: I worker with same data as the holotype ; 4 workers, Eneabba, ii.l980, M. Sartori & R. Stone, minesite, rehab. study A1372 E80, JDM 525 (2 pins each to, ); 1 worker, 5 km E of Burakin, 29.iv.l989, B. E. Heterick, soil, native veg., rural environ., 521/6MonBH45 (ANIC); 1 worker, 5 km E Ledge Point, 10.iii.1989, B. E. Heterick, soil, native veg., rural environ., 510/6MonBH42 (ANIC).



Etymology
Greek: “short-haired”.