Chelaner insolescens

Little has been published on the biology of C. insolescens, but Andersen (1991a: 448) mentions that it is almost exclusively graminivorous (feeding on grass).

Identification
Heterick (2001) - A member of the insolescens group. Chelaner insolescens has a highly variable morphology, but as here defined almost certainly includes a complex of species. Compared with the type workers, several specimens are considerably larger and show distinct clypeal characters, a flattened and almost carinate anterior promesonotum, and an elliptical dorsum to the node. Additional variants are held in the A. Andersen collection. However, the group can be distinguished from all other Chelaner by the highly developed anteroventral postpetiolar process. Furthermore, larger specimens have a distinctive indentation on the ventral face of the petiole near its junction with the postpetiole.

The male from Bamboo Ck is bright orange-red with thick antennae, contrasting with the smaller brown paralectotype male. Nonetheless, the structure of the alitrunk and the petiole clearly place the specimen within the insolescens-group.

Since the taxon is known from so few specimens, it is difficult to determine the species status of all material examined. The erection of a lectotype fixes the species name for the smaller specimens with a rounded promesonotum and cuboidal (rather than elliptical) petiolar node.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  insolescens. Monomorium (Notomyrmex) insolescens Wheeler, W.M. 1934d: 145 (w.m.) AUSTRALIA.
 * Combination in Monomorium: Taylor, 1987b: 3.
 * Combination in Chelaner: Ettershank, 1966: 97; Sparks et al., 2019: 232.
 * See also: Heterick, 2001: 383.

Worker
Length 2.5-3 mm.

Head subrectangular, slightly longer than broad and scarcely broader jn front than behind, with feebly convex sides and concave posterior border. Eyes rather large, moderately convex, situated about their own length from the anterior corners of the head. Mandibles broad, their masticatory borders with five regular teeth, their external borders rather straight. Clypeus very short, strongly bicarinate, the carinae projecting anteriorly as two stout teeth, separated by a deep concavity. Frontal carinae flattened, horizontal, slightly lobulate behind the antennal insertions; frontal area small, indistinct, impressed; frontal furrow obsolete. Antennae 12-jointed, scapes reaching to about twice their greatest diameter from the posterior corners of the head; joints 2-7 of the funiculi a little broader than long; eighth joint as long as broad; club 3-jointed, its two basal joints subequal and together as long as the terminal joint. Thorax stout, about twice as long as broad, and nearly as broad as the head through the humeri, which are rounded, both the pro-mesonotal and the mesoepinatol sutures absent. Mesonotum and epinotum laterally compressed. In profile the thorax is convex in front, the dorsal outline straight, without mesoepinotal impression or constriction, sloping slightly at the base of the epinotum which is feebly angular in the middle in profile, longer than the declivity, which bears at its middle on each side a blunt denticle continued down as a ridge to the well-developed, translucent metasternal angle. Petiole and postpetiole stout, the peduncle of the former very short, the node subcuboidal, a little higher than long, with perpendicular anterior and posterior surfaces and horizontal summit; from above broader than long, rounded in front and straight behind. Postpetiole with a prominent acute tooth at its anteroventral end, the node somewhat lower than that of the petiole, also subcuboidal in profile, as long as high, rectangular from above, distinctly broader than long and broader than the petiolar note. Gaster small, lenticular, scarcely longer .than broad, convex above, with concave anterior border. Legs rather stout.

Shining; mandibles smooth, sparsely punctate; bead covered with scattered, piligerous punctures, cheeks and front longitudinally rugulose; thorax, petiole and postpetiole subopaque, densely and finely punctate, except the upper surface of the pronotum which is smooth and shining; meso- and metapleurae vaguely, longitudinally rugulose. Gaster and legs smooth and shining; sparsely punctate.

Hairs yellow, sparse, erect, moderately long on the body, shorter and more numerous on the legs and scapes.

Red; pedicel and posterior portion of thorax darker; head and antennae paler; gaster and legs, including coxae, yellow.

Heterick (2001) - HML 2.05-3.55; HL 0.72-1.18; HW 0.59-1.04; Cei 78-91; SL 0.52-0.98; SI 85-102; PW 0.41-0.81 (16 measured). Lectotype. HML 2.46; HL 0.85; HW 0.67; Cel 78; SL 0.67; SI 0.67; SI 100; PW 0.48.

Head. Head square or rectangular; vertex slightly concave; frons smooth and shining with combination of appressed setulae and erect and suberect setae. Compound eyes elliptical; (viewed from front) compound eyes set in anterior half of head capsule; (viewed laterally) compound eyes set posterior of midline of head capsule, or set at midline of head capsule; eye moderate, eye width 0.5-1.5 x greatest width of antennal scape to large, eye width greater than 1.5x greatest width of antennal scape. Antennal segments 12; club three-segmented. Anteromedial clypeal margin emarginate, median clypeal carinae produced as pair of bluntly rounded denticles. Longest lateral anterior clypeal setae long, extending beyond dorsal margin of closed mandibles. Posteromedial clypeal margin level with posterior surface of antennal fossae. Anterior tentorial pits situated nearer antennal fossae than mandibular insertions. Frontal lobes parallel straight. Venter of head capsule without elongate, basket-shaped setae. Palp formula 2,3. Maximum number of mandibular teeth and denticles: five; mandibles (viewed from front) triangular and smooth, with piliferous punctures; basal tooth not enlarged; basal angle indistinct; apical and basal mandibular margins meeting in tooth or denticle.

Alitrunk. Promesonotal sculpture absent with promesonotum smooth and shining, or promesonotum mainly smooth and shining with limited microreticulation and striolae on and around katepisternum; dorsal promesonotal face convex anteriad, otherwise flattened to evenly flattened; erect and suberect promesonotal setae greater than 10; setulae appressed. Mesonotal suture absent. Metanotal groove absent. Propodeal sculpture absent; propodeum smooth and shining, or present as faint microreticulation with few striae, mainly on lower lateral surface; dorsal propodeal face strongly 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); lobes present as blunt flanges. Propodeal angle absent; declivitous face of propodeum smoothly convex to flat. Erect and suberect propodeal setae 5-1 0; propodeal setulae decumbent and subdecumbent. Propodeal spiracle lateral and nearer declivitous face of propodeum than metanotal groove; vestibule conspicuous through cuticle.

Petiole and postpetiole. Petiolar spiracle lateral and slightly anteriad of petiolar node to lateral and positioned in pedicel well anteriad of petiolar node. Petiolar node variable: from cuboidal and inclined posteriad to narrow and elliptical; sculpture absent, petiolar node smooth and shining, or sculpture present in form of microreticulation. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 1:1 to near 3:4. Anteroventral process always absent or vestigial. Ventral lobe always absent. Height ratio of petiole to postpetiole near 3:4; height-length ratio of postpetiole near 4:3. Sculpture present in form ofmicroreticulation. Ventral process present and distinct.

Gaster. Pilosity of first gastral tergite consisting of combination of appressed setulae and longer, erect and suberect setae.

General characters. Colour of head, alitrunk, petiole and postpetiole dark orange to shining russet (head may be lighter than alitrunk), gaster and appendages amber. Worker caste monomorphic but variable in size, with series of intercastes between largest and smallest workers (monophasic allometry).

Male
Length 2.5 mm.

Heading including the eyes about as long as broad; hroadly convex behind; eyes and ocelli very large, cheeks very short; mandibles small 5-toothed; clypeus convex in the middle, with evenly rounded anterior border; frontal carinae short but distinct. Antennal scapes four times as long as broad, cylindrical, somewhat curved, first funicular joint as long as broad, not globose, the remaining joints longer but not narrowing distally. Thorax small and short, not broader than the head. Mesonotum convex, overarching the pronotum in front, without notauli (Mayrian furrows); scutellum rather small, not prominent. Epinotum sloping, without distinct base and declivity. Petiolar and postpetiolar nodes similar to those of the worker but smaller, lower and more rounded. Gaster small; genitalia prominent, the stipites thin, broad, rounded and incurved. Legs moderately slender. Wings with well-developed veins and pterostigma, with a discoidal and one cubital cell and the marginal cell open at the apex.

Mandibles shining, sparsely punctate; head opaque, densely and finely punctate; thoracic sculpture much as in the worker, but the sides of the epinotum and pedicel loosely, longitudinally rugulose.

Hairs shorter than in the worker and more abundant on the thorax and appendages.

Black; gaster, thoracic sutures and legs piceous; wings greyish hyaline, with pale brown veins and pterostigma.

Heterick (2001) - HML 3.05; HL 0.78; HW 0.78; CeI 1 00; SL 0.31; SI 40; PW ? (promesonotum obscured) (1 measured).

Head. Compound eyes protuberant and elliptical; (viewed laterally) compound eyes set posterior of the midline of head capsule; ocelli conspicuous and turreted. Ratio of length of first funicular segment of antenna to length of second funicular segment near 1:3. Number of mandibular teeth and denticles: five.

Alitrunk. Mesoscutum in profile evenly flattened; dorsal appearance of mesoscutum smooth and shining; mesoscutal pilosity consisting of long, dense setae. Parapsidal furrows vestigial; notauli absent. Axillae separated by distance more than half greatest width of scutellum.

Wing. Wing veins tubular and strongly sclerotised; vein m-cu present as an entire vein enclosing first discoidal cell; vein cu-a present.

Petiole and postpetiole. Petiolar spiracle lateral and slightly anteriad of petiolar node. Sculpture absent, petiolar node smooth and shining; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 3:4. Anteroventral process always absent or vestigial; ventral lobe always absent. Height-length ratio of postpetiole near 2:1; sculpture absent on dorsum, at least: postpetiole smooth and shining; ventral process present and distinct.

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

General characters. Colour orange.

Type Material
Heterick (2001) - Lectotype. One worker, Western Australia, Derby, W. D. Dodd (MV-“Cotype 20864”; “Paratype worker T-15057”), here designated. [A syntype worker has been chosen to become the lectotype, so as to fix the species name for the typical form of M. insolescens.] Paralectotypes. Western Australia: 5 workers, 1 male, same data as lectotype ; 1 worker same data as lectotype (MY); here designated.

Described from six workers and two males taken by W. D. Dodd at Derby, West Australia.