Chelaner euryodon

Widespread throughout Australia, reaching at least as far north as the central Queensland coast. The ant prefers sandy soils.

Identification
Heterick (2001) - A member of the rubriceps group. Chelaner euryodon may be confused with some forms of Chelaner leae, but can be distinguished by the enlarged basal tooth, and presence of true polymorphism in the worker caste.

Heterick (2009) - The broad basal tooth on its mandible and its strongly polymorphic workers distinguish this widely ranging but rare species.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  euryodon. Monomorium euryodon Heterick, 2001: 424, figs. 11, 44, 91 (w.q.m.) AUSTRALIA.
 * Combination in Chelaner: Sparks et al., 2019: 232.

Worker
Worker. HML 2.63; HL 0.97; HW 0.89; Cel 92; SL 0.61; SI 69; PW 0.51. Others. HML 1.54-2.99; HL 0.58-1.07; HW 0.46-1.04; CeI 78-96; SL 0.34-0.64; SI 60-82; PW 0.32-0.66 (29 measured).

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

Head. Head square or rectangular, or cordate. Compound eyes elliptical; (viewed from front) compound eyes set in anterior half of head capsule. Anteromedial clypeal margin convex, straight or slightly emarginate, median clypeal carinae indistinct. Posteromedial clypeal margin level with posterior surface of antennal fossae. Frontal lobes parallel, sinuate. Basal tooth enlarged, much broader than other non-apical teeth.

Alitrunk. Dorsal promesonotal face convex anteriad, otherwise flattened. Metanotal groove present as feebly impressed furrow between promesonotum and propodeum. Propodeal sculpture present as faint microreticulation with few striae, mainly on lower lateral surface; propodeal processes absent (propodeum smoothly rounded in profile or with slight hump at propodeal angle). Propodeal angle absent; declivitous face of propodeum longitudinally concave between its lateral margins. Erect and suberect propodeal setae greater than 10; propodeal setulae decumbent and subdecumbent.

Petiole and postpetiole. Petiolar spiracle lateral and in anterior sector of petiolar node. Petiolar node cuneate, dorsally rounded; sculpture absent, petiolar node smooth and shining. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 2: 1, or near 4:3. Anteroventral process distinct in some individuals as slender carina that tapers posteriad. Height ratio of petiole to postpetiole near 1: l to near 4:3; height-length ratio of postpetiole near 2:1 to near 4:3. Sculpture absent on dorsum, at least: postpetiole smooth and shining.

General characters. Colour fulvous to deep orange. Worker caste polymorphic.

Queen
HML 3.44-3.78; HL 1.01-1.09; HW 1.01-1.14; CeI 95-105; SL 0.70-0.75; SI 64-74; PW 0.98 (4 measured).

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

Head. Head square or rectangular, or cordate; frons striolate with a combination of appressed setulae and erect and suberect setae. Compound eyes circular or subcircular; (viewed laterally) compound eyes set at midline of head.

Alitrunk. Mesoscutum in profile evenly flattened. Mesoscutal pilosity consisting of dense incurved setulae and setae; 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 faint microreticulation with few striae, mainly on lower lateral surface; dorsal propodeal face flattened. Propodeal processes present on posterior propodeal angles as small denticles or sharp flanges. Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum.

Wing. Vein m-cu absent.

Petiole and postpetiole. Petiolar spiracle lateral and in anterior sector of petiolar node. Petiolar node cuneate, dorsally rounded. Anteroventral process distinct in some individuals as slender carina that tapers posteriad. Height ratio of petiole to postpetiole near 3:4 to near l: 1; height-length ratio of postpetiole near 3: 1. Sculpture present in form of microreticulation.

General characters. Colour of head, alitrunk, petiole, postpetiole russet; gaster, legs amber. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

Male
HML 2.84-2.90; HL 0.75-0.83; HW 0.84-0.93; CeI 113-118; SL 0.21; SI 22-25; PW 0.75-0.78 (2 measured).

As for the male of Chelaner leae, but with the following apomorphies.

Head. Head width-mesoscutal width ratio near 4:3. Ratio of length of first funicular segment of antenna to length of second funicular segment near 1:2. Maximum number of mandibular teeth and denticles: four.

Alitrunk. Mesoscutum in profile evenly convex; dorsal appearance of mesoscutum striolate and microreticulate; mesoscutal pilosity consisting of numerous short setae, incurved medially. Parapsidal furrows present and distinct.

Wing. Vein m-cu absent.

Petiole and postpetiole. Anteroventral process distinct in some individuals as slender carina that tapers posteriad. Height-length ratio of postpetiole near 4:3; sculpture present in form of microreticulation; ventral process present and distinct.

General characters. Brown.

Type Material
Holotype. Worker (top point), South Australia, 36 miles NW Adelaide, 15.viii.1971, B. B. Lowery, sandy coastal heath, nest in sand, SA 357, ANIC ants, via\66.16. Paratypes. Queensland: 2 workers, 5 km NE Mount Morgan 23°37'S, 150°24'E, 27.x.1976, R. W. Taylor & T. A. Weir, ace. no. 76/246, ANIC ant vial 66.15 (ANIC); 1 queen, 5 workers, St George, 19.i.1966, B. B. Lowery, black soil, plain box timber, large series under small shrub in sandy debris, R.66 ; 2 workers, Taroom, 20.viii.1975, B. B. Lowery, brigalow and box trees, in soil ; 1 queen, 7 workers (1 head missing), 4 miles WNW Yelarbon, l.iii.1949, T. Greaves, 6966 (MCZ). South Australia: 1 queen, 2 males, 2 workers with same data as the holotype (ANIC).



Etymology
Greek: “broad-toothed”.

References based on Global Ant Biodiversity Informatics

 * CSIRO Collection
 * Heterick B. E. 2001. Revision of the Australian ants of the genus Monomorium (Hymenoptera: Formicidae). Invertebrate Taxonomy 15: 353-459.
 * Heterick B. E. 2009. A guide to the ants of south-western Australia. Records of the Western Australian Museum Supplement 76: 1-206.
 * Heterick B. E. 2013. A taxonomic overview and key to the ants of Barrow Island, Western Australia. Records of the Western Australian Museum Supplement 83: 375-404.
 * Majer J. D., S. K. Callan, K. Edwards, N. R. Gunawardene, and C. K. Taylor. 2013. Baseline survey of the terrestrial invertebrate fauna of Barrow Island. Records of the Western Australian Museum Supplement 83: 13-112.