Chelaner longiceps

In Australian mainland states Chelaner longiceps is a relatively common and widespread red or red-and-brown ant that has been collected from both ground and vegetation. Some populations can still be found in relictual bushland in the Perth metropolitan area and on Rottnest Island (Heterick 2009).

Identification
Heterick (2001) - A member of the rubriceps group. A reddish-orange species, a color shared with numerous other dry sclerophyll woodland Chelaner. Chelaner longiceps is rather variable in appearance. Infuscation of the propodeum, petiole and postpetiole may be present or absent. The morphology may also vary: some workers are more robust than the typical form, with a strongly rugose alitrunk and pronounced clypeal teeth.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Biology
Heterick (2001) - This species is one of several red or reddish-orange Chelaner that are mostly found in dry sclerophyll woodlands, particularly those dominated by mallee or Acacia spp. This ant has been taken by vegetation sweeps, hand collection in litter, and in pitfall traps.

Nomenclature

 *  longiceps. Monomorium (Notomyrmex) longiceps Wheeler, W.M. 1934d: 146 (w.) AUSTRALIA.
 * Heterick, 2001: 432 (q.).
 * Combination in Monomorium: Taylor, 1987b: 3.
 * Combination in Chelaner: Ettershank, 1966: 97; Sparks et al., 2019: 233.

Worker
Length 2.3-2.8 mm.

Averaging slightly smaller than Chelaner insolescens and differing in the following characters: Head trapezoidal, longer, narrower and more distinctly broader in front than behind, with straight sides; eyes smaller and nearer the middle of the sides; mandibles narrower, 4-toothed; antennal scapes shorter as are also joints 2-8 of the funiculus. Epinotum in profile rectangular, the declivity perpendicular, with the denticles larger and continued as crenulated ridges to the metasternal angles, which are small and poorly developed. Peduncle of petiole longer, more sharply marked off from the node. This and the postpetiole are of the same width but much more rounded and less cuboidal than in insolescens; petiolar node from above as long as broad, rather narrowly rounded in front, contracted behind; postpetiole subtrapezoidal one and one-third times as broad as long, broader in front than behind, with rounded corners and short, straight, posteriorly converging sides.

Sculpture of the head similar to that of insolescens, but the longitudinal rugules are continued back beyond its middle and the sparse punctures on its posterior portion are coarser. Mandibles rather coarsely striate-punctate. Thorax longitudinally rugulose throughout, except the declivity of the epinotum which is transversely striate; dorsal portion of pronotum more loosely rugose and therefore more shining than the remainder of the thorax. Petiolar node above arcuately rugulose; postpetiole with a few short, longitudinal sulci. Gaster smooth and shining, with very sparsely, piligerous punctures.

Pilosity somewhat more abundant than in insolescens.

Colour of the head and thorax the same, but the gaster is also red and not yellow and the antennae and legs are brownish red, darker than the head and thorax, the tarsi paler.

Heterick (2001) - HML 1.85-2.49; HL 0.67-0.91; HW 0.56-0.74; CeI 75-84; SL 0.48-0.63; SI 84-93; PW 0.32-0.48 (28 measured).

Head. Head square or rectangular; vertex planar; frons microreticulate and striolate with combination of incurved decumbent and subdecumbent setulae and erect and suberect setae. Compound eyes circular or subcircular; (viewed from front) compound eyes set in anterior half of head capsule; (viewed laterally) compound eyes set at midline of head capsule; eye moderate, eye width 0.5-1.5x 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 apically as pair of pronounced teeth, or emarginate, median clypeal carinae produced apically as pair of pronounced teeth, with an additional tooth or denticle on either side, or straight or slightly emarginate, median clypeal carinae not produced as teeth or 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, or parallel, sinuate. 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 striate, with piliferous punctures; basal tooth not enlarged; basal angle indistinct; apical and basal mandibular margins meeting in tooth or denticle.

Alitrunk. Promesonotal sculpture present in form of microreticulation and rugosity over entire promesonotum; dorsal promesonotal face convex anteriad, otherwise flattened; erect and suberect promesonotal setae greater than 10; setulae decumbent and subdecumbent. Mesonotal suture absent, or visible as fine line under transparent surface of cuticle. Metanotal groove absent, or present as feebly impressed furrow between promesonotum and propodeum. Propodeal sculpture present as uniform rugosity, with well defined costulae on declivitous face of propodeum; dorsal propodeal face sloping posteriad, with wedge-shaped flattening or shallow depression that is widest between propodeal angles; processes present on posterior propodeal angles as small denticles or sharp flanges; lobes present as blunt flanges. Propodeal angle present; length ratio of dorsal face to declivitous face near 2:1 to near 4:3; declivitous face of propodeum flat. Erect and suberect propodeal setae greater than 10; propodeal setulae decumbent and subdecumbent. Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum; vestibule conspicuous through cuticle.

Petiole and postpetiole. Petiolar spiracle lateral and slightly anteriad of petiolar node. Petiolar node cuboidal, or tumular and inclined posteriad; sculpture present; petiolar node rugose. 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 present as pronounced spur. Ventral lobe always absent. Height ratio of petiole to postpetiole near 1:1 to near 4:3; height-length ratio of postpetiole near 4:3. Sculpture present in form of microreticulation, or present; postpetiole rugose. 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 and anterior promesonotum reddish orange to fulvous, variously infuscated with brown in some individuals, posterior promesonotum, propodeum, petiole and postpetiole concolorous with these parts, or darkly infuscated, gaster orange to red, legs and antennae orange through to dark brown. Worker caste monomorphic.

Heterick (2001) - HML 2.97-3.26; HL 0.93-0.98; HW 0.78-0.88; Cel 83-89; SL 0.67; SI 87; PW 0.72 (2 measured).

Head. Head rounded; vertex slightly concave; frons longitudinally striate with combination of incurved decumbent and subdecumbent setulae and erect and suberect setae. Compound eyes circular or subcircular, or elliptical; (viewed from front) compound eyes set in posterior half of head capsule, or set in anterior half of head capsule; (viewed laterally) compound eyes set at midline of head capsule; eye large, eye width greater than 1.5 x greatest width of antennal scape.

Alitrunk. Mesoscutum in profile evenly flattened. Mesoscutal pilosity consisting of dense in curved setulae and setae; dorsal appearance of mesoscutum striolate and microreticulate; length-width ratio of mesoscutum and scutellum combined near 4:3. Axillae separated by distance less than half greatest width of scutellum. Propodeal sculpture present as uniform rugosity, with well defined costulae on declivitous face of propodeum; dorsal propodeal face flattened. Propodeal processes present on posterior propodeal angles as small denticles or sharp flanges; lobes present as blunt flanges. Propodeal angle present. Erect and suberect propodeal setae greater than 10; propodeal setulae decumbent and subdecumbent. Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum.

Petiole and postpetiole. Petiolar spiracle lateral and slightly anteriad of petiolar node. Petiolar node cuneate, dorsally rounded; sculpture present in form of microreticulation. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 2:1 to near 4:3. Anteroventral process always present as pronounced spur. Height ratio of petiole to postpetiole near 1: 1; height-length ratio of postpetiole near 2: 1. Sculpture present in form of microreticulation; ventral process present and distinct.

Wing. Dealate

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

General characters. Colour tawny orange; propodeum infuscated with brown; appendages brown. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

Type Material
Described from a single specimen which I found running on the ground near Lady Edeline Beach (X.23.'31), and two workers from Ludlow, Western Australia, received from Mr. John Clark.

Heterick (2001) - Lectotype. One worker, Western Australia, Ludlow, J. Clark (MCZ-'Cotype' 23233), here designated. [A syntype worker has been chosen to become a lectotype, so as to fix the species name for the typical form of M. longiceps, i.e. an ant with dark appendages and tumular rather than cuboidal petiolar node. The other syntype specimen on the pin becomes a paralectotype.] Paralectotype. One worker, same data as lectotype, here designated.