Chelaner gilberti

Biological data is lacking for the few specimens available for study. However, one worker from the MacDowall Range, north of Daintree, was recovered from a pyrethrum knockdown, and three specimens from Tolga were collected from a log. (Heterick 2001)

Identification
Heterick (2001) - A member of the rubriceps group. This ant is very distinctive, and Australian specimens vary only in the width of the head capsule and the thickness of the node. At the time of this research, I had available for study only two extralimital specimens, a worker from New Guinea and a queen from Rose Island, Papua. The New Guinean worker differs from Australian workers only in its uniformly dark chocolate colouration, more rounded propodeum and obliquely inclined postpetiolar node. The queen exhibits the same colouration as a M. gilberti queen from northeast Queensland. Later, I received on loan a type of Chelaner edentatus. This worker was collected 4.iii.1890 by L. Loria on “Woodlajk” (=Woodlark Island). The ant is of the same colouration and general habitus as the New Guinean worker. However, since there was no other material available for detailed comparison at the time of this research, the taxonomic relationship between M. edentatus and M. gilberti has been left open for the present.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: New Guinea.

Nomenclature

 *  gilberti. Monomorium gilberti Forel, 1902h: 440 (w.) AUSTRALIA.
 * Heterick, 2001: 426 (q.).
 * Combination in M. (Notomyrmex): Emery, 1922e: 169.
 * Combination in Monomorium: Taylor, 1987b: 2.
 * Combination in Chelaner: Ettershank, 1966: 97; Sparks et al., 2019: 232.
 * Senior synonym of mediorubra, turneri: Heterick, 2001: 426.
 * turneri. Vollenhovia turneri Forel, 1910b: 26 (w.) AUSTRALIA. Combination in Monomorium: Emery, 1914f: 407 (footnote); in M. (Notomyrmex): Emery, 1922e: 169; in Chelaner: Ettershank, 1966: 97; in Monomorium: Bolton, 1987: 284. Junior synonym of gilberti: Heterick, 2001: 426.
 * mediorubra. Monomorium gilberti var. mediorubra Forel, 1915b: 72 (w.) AUSTRALIA. Combination in M. (Notomyrmex): Emery, 1922e: 169; in Chelaner: Ettershank, 1966: 97; in Monomorium: Taylor, 1987b: 2. Subspecies of gilberti: Taylor & Brown, D.R. 1985: 56. Junior synonym of gilberti: Heterick, 2001: 426.

Heterick (2001) - Forel's association (Forel 1910) of this species with the genus Vollenhovia is puzzling; the more so, since he had correctly described the same ant as a Monomorium 12 years earlier. Chelaner gilberti completely lacks the large subpetiolar process found in Vollenhovia.

Worker
Heterick (2001) - HML 2.80-3.44; HL 0.93-1.16; HW 0.75-1.06; CeI 80-98; SL 0.57-0.76; SI 76-98; PW 0.52-0.64 (11 measured.)

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

Head. Head square or rectangular; frons smooth and shining with combination of appressed setulae and erect and suberect setae. Mandibles (viewed from front) triangular and smooth, with piliferous punctures, or triangular and striate, with piliferous punctures.

Alitrunk. Promesonotal setulae appressed. 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, or present as uniform rugosity, with well defined costulae on declivitous face of propodeum; dorsal propodeal face strongly convex, or 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 >5; propodeal setulae appressed.

Petiole and postpetiole. Petiolar node cuboidal; 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. Height-length ratio of postpetiole near 4:3 to near 1:1.

General characters. Colour of head chocolate to black, anterior promesonotum russet to chocolate, propodeum dark red, petiole and postpetiole chocolate, appendages chocolate. Worker caste monomorphic.

Queen
Heterick (2001) - HML 4.40; HL 1.40; HW 1.27; CeI 91; SL 0.78; SI 61; PW 0.93 (1 measured.)

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

Head. Head square or rectangular; vertex planar; frons striolate between frontal carinae, otherwise smooth and shining with a combination of decumbent and subdecumbent setulae and erect and suberect setae. (Viewed laterally) compound eyes set posterior of the midline of head capsule.

Alitrunk. Axillae contiguous or nearly so. Propodeal processes absent (propodeum angulate in profile), or present on posterior propodeal angles as small denticles or sharp flanges. Propodeal angle present. Propodeal spiracle lateral and nearer metanotal groove than declivitous face of propodeum.

Petiole and postpetiole. Petiolar node cuboidal; striolate and shining. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 4:3. Anteroventral process distinct in some individuals as slender carina that tapers posteriad. Height-length ratio of postpetiole near 4:3.

General characters. Colour generally reddish-brown to russet; petiole and postpetiole lighter in colour. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.