Chelaner punctulatus

The four known specimens of C. punctulatum were collected in a pitfall trap in a sand-dune 102 km SE of Newman in the Mid West Region of Western Australia, as part of a CALM survey. Interestingly, the ant fauna collected in this general area during the survey appears to have a greater affinity with that of far northern and north-eastern Australia than with the ant fauna of the adjacent Pilbara Region. (Heterick 2003)

Identification
Heterick (2003) - Distinguished from other Chelaner in the rubriceps species-group by a combination of its shagreenate and finely microreticulate sculpture, and its large eyes.

Chelaner punctulatum belongs to the Chelaner rubriceps species-group, as evidenced by certain of its features, namely the shape of the node, the number of mandibular teeth (five), and the compact postpetiole. Within the C. rubriceps group, C. punctulatum closely resembles Chelaner leae (especially specimens originally placed under Chelaner flavipes and Chelaner insulare, and also Chelaner centrale, but may be separated from these close relatives through its larger eye and shagreenate sculpture. The exotic Monomorium pharaonis has a similar body sculpture, but the shape of the node is quite different and the metanotal groove is a distinct furrow in this species. Moreover, M. pharaonis is a tramp species, rarely found far from built-up areas.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  punctulatum. Monomorium punctulatum Heterick, 2003: 251, figs. 1, 4, 5 (w.) AUSTRALIA.
 * Combination in Chelaner: Sparks et al., 2019: 233.

Worker
Holotype. HML 1.69; HL 0.58; HW 0.48; CeI 82; SL 0.39; SI 81; PW 0.34. Other workers. HML 175–1.90; HL 0.59–0.61; HW 0.47–0.50; CeI 78–81; SL 0.41–0.43; SI 88–90; PW 0.32–0.37 (3 measured).

Head. Head rectangular, vertex planar; frons densely microreticulate with minute, inwardly curved, decumbent setae directed towards the midline of the head capsule, and almost invisible in some lights. Compound eyes elliptical; (viewed from front) eyes set slightly below midpoint of head capsule; (viewed from side) eyes set slightly posterior of midline of head capsule; eye size large, about 2 times width antennal scape. Antennal segments 12; antenna with 3-segmented club. Anteromedian portion of clypeus bicarinate, protruding narrowly, median clypeal carinae not produced apically as teeth or denticles; median seta present on anterior margin of clypeus; longest lateral anterior setae long, extending beyond dorsal margin of closed mandible; posterior clypeal margin extending slightly posteriad of posterior surface of antennal fossae; anterior tentorial pits straight; venter of head capsule without long, strongly curved setae. Palp formula unknown (palps not visible in specimens seen). Mandibles subtriangular, smooth and shining with scattered piliferous punctures; mandibles each with five teeth and denticles; basal tooth a tiny denticle; basal angle of mandible distinct, apical and basal mandibular margins ending in a denticle. Alitrunk (Fig. 5). Promesonotal sculpture in form of dense microreticulation, heavier sculpture lacking, matt in appearance; in profile, dorsal promesonotal face very gently concave anteriad, otherwise flattened; short, erect setae sometimes present on humeral angles, otherwise promesonotal setae very short and decumbent or appressed. Mesonotal suture absent. Metanotal groove virtually absent. Propodeal sculpture in form of dense microreticulation, with a few faint striae on lower lateral surface; dorsal propodeal face flattened anteriad, sloping gradually toward propodeal declivity posteriad, propodeal processes absent (propodeum bluntly angulate in profile); metapleural lobes present as blunt flanges; length ratio of dorsal propodeal face to its declivous face near 2:1; declivous face of propodeum flat; propodeal setae minute, appressed, almost invisible; propodeal spiracle lateral and about midway between metanotal grove and declivous face of propodeum; propodeal spiracular vestibule indistinct. Petiole and postpetiole (Fig. 5). Petiolar spiracle minute, lateral and positioned slightly ahead of petiolar node; in profile, peduncle of moderate length, its length slightly less than width of node (in profile). In profile, shape of petiolar node cuboidal to subcuboidal; sculpture of node densely microreticulate; ratio of greatest node breadth (i.e., viewed from front) to greatest node width (i.e., viewed in profile) between 1:1 and 1:2; subpetiolar process absent or vestigial, an anteroventral process present in some individuals as a small spur. Height-length ratio of postpetiole between 1:1 and 1:2; sculpture of postpetiole present in form of dense microreticulation; ventral process on postpetiole present and distinct. Gaster. Pilosity of first gastral tergite consisting of combination of erect and decumbent yellowish setae of approximately the same length; surface of sclerites smooth and shining. General characters. Colour of head, alitrunk and nodes orange-yellow, gaster and legs yellow. Worker caste apparently monomorphic.

Type Material
Holotype. Western Australia. Worker (bottom point), 102.5 km SSE Newman 24°06′16′S, 120°19′36′E, viii. 1997, S. van Leeuwin & R. N. Bromilow, Perm. invert. pitfall trap, C4, Sand dune. Paratype: 1 worker (top point) with same data as holotype (ANIC).

The four specimens of Chelaner punctulatum were donated by Department of Conservation and Land Management (CALM). The holotype and one paratype of C. punctulatum were deposited with the Australian National Insect Collection. Two specimens of the latter were retained by the JDM Collection, Curtin University of Technology, Bentley, Western Australia, Australia.



Etymology
Latin adjective ‘minutely dotted’.