Chelaner tambourinensis

This species is a cryptic forager in cool temperate and tropical montane forests. Habitats include moss, rotten logs and leaf litter. Specimens taken from Lord Howe Island in 1972 were found nesting in subfossil bird bones.

Identification
Heterick (2001) - A member of the kilianii group. Chelaner tambourinensis can be distinguished from the similar Chelaner kiliani on the basis of the characters mentioned in the key to Chelaner species based on workers. This species also resembles Chelaner leae, from which it differs chiefly in the length of the petiolar peduncle and the shape of the postpetiole. Chelaner tambourinensis is very variable in colour, but is more uniform in morphology than either C. leae or C. rubriceps, the other widespread east coast Chelaner.

Monomorium howense has a yellow or orange head and gaster, and reddish-orange alitrunk, while the type of C. tambourinensis is brown with a yellow gaster and pale appendages. The C. tambourinensis colour morph is more common in northern New South Wales and southern Queensland, though it occurs elsewhere. Other colour patterns forming a continuum between these two extremes are common, and a pale yellow morph occurs on the Bellenden Ker range, thus there is no justification for M. howense and C. tambourinensis to be considered as anything other than colour varieties of a widespread species. Consequently, M. howense is here synonymised under the senior name C. tambourinensis.

Distribution based on Regional Taxon Lists
Australasian Region: Australia, Lord Howe Island.

Nomenclature

 *  tambourinensis. Monomorium kiliani var. tambourinensis Forel, 1915b: 71 (w.q.) AUSTRALIA.
 * Wheeler, G.C. & Wheeler, J. 1960b: 17 (l.).
 * Combination in M. (Notomyrmex): Emery, 1922e: 169.
 * Combination in Monomorium: Taylor, 1987b: 3.
 * Combination in Chelaner: Ettershank, 1966: 97; Sparks et al., 2019: 233.
 * Raised to species: Wheeler, G.C. & Wheeler, J. 1960b: 17.
 * Subspecies of kiliani: Taylor & Brown, D.R. 1985: 57.
 * Revived status as species and senior synonym of howense: Heterick, 2001: 389.
 * howense. Monomorium (Notomyrmex) howense Wheeler, W.M. 1927i: 138, fig. 5 (w.q.) AUSTRALIA. Combination in Chelaner: Ettershank, 1966: 97; in Monomorium: Taylor, 1987b: 2. Junior synonym of tambourinensis: Heterick, 2001: 389.

Worker
Heterick (2001) - HML 1.41-2.48; HL 0.50-0.81; HW 0.40-0.72; Cel 76-90; SL 0.36-0.67; SI 86-102; PW 0.28-0.50 (54 measured).

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

Head. Head square or rectangular; vertex slightly concave to planar. (Viewed laterally) compound eyes set at midline of head capsule. Anteromedial clypeal margin straight or slightly emarginate, median clypeal carinae not produced as teeth or denticles. Posteromedial clypeal margin level with posterior surface of antennal fossae. Palp formula 2,2. Maximum number of mandibular teeth and denticles: five; mandibles (viewed from front) triangular and smooth, with piliferous punctures.

Alitrunk. Mesonotal suture absent. Propodeal sculpture present as faint microreticulation with few striae, mainly on lower lateral surface, or present as uniform rugosity, with well defined costulae on declivitous face of propodeum. Propodeal angle absent; declivitous face of propodeum longitudinally concave between its lateral margins.

Petiole and postpetiole. Petiolar node conical, dorsally rounded, or 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 1:1, or near 3:4. Height-length ratio of postpetiole near 4:3 to near 3:4.

General characters. Colour very variable: two distinctive colour morphs: 1. head, alitrunk, petiole and postpetiole shining russet, gaster bright tawny yellow to russet, often with one or more brown bands, appendages a creamy yellow to amber; 2. head tawny yellow, alitrunk, petiole and postpetiole yellow, reddish-orange or fulvous, gaster as for 1., legs tawny yellow: other series yellowish, orange or dull brown with varying degrees of infuscation, particularly of propodeum. Worker caste monomorphic.

Queen
Heterick (2001) - HML 2.00-2.77; HL 0.62-0.82; HW 0.55-0.72; Cei 86-93; SL 0.45-0.64; SI 78-79; PW 0.48-0.71 (12 measured).

As for the queen of Chelaner kiliani, 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

Alitrunk. Mesoscutum in profile evenly convex, or convex anteriad; thereafter flattened. Mesoscutal pilosity consisting of dense incurved setulae and setae. Propodeal processes absent (propodeum angulate in profile). Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum.

Petiole and postpetiole. Petiolar node cuneate, dorsally rounded; sculpture absent, petiolar node smooth and shining. Height ratio of petiole to postpetiole near 1:1, or near 4:3; height-length ratio of postpetiole near 2:1, or near 4:3.

General characters. Colour variable: often tawny yellow or shining russet, alone or in combination. If alitrunk infuscated, head and gaster usually of lighter colour, gaster sometimes with transverse brown banding. Brachypterous alates not seen. Ergatoid or worker-female intercastes seen and examined.