Chelaner whitei

A seed harvesting species with polymorphic workers (Davison 1982, 1987).

Identification
Heterick (2001) - A member of the bicorne group. The whereabouts of extant type specimens of Monomorium whitei are unknown. Wheeler's thorough description of the ant, and his accompanying diagrams, leave no doubt as to its identity (it is the largest Australian Monomorium). Labels identifying specimens as “whitei” can also be found among the material from the various Australian museums. McAreavey distinguished his Monomorium armstrongi from M. whitei on the basis of the latter's supposedly smaller size and different colouration (McAreavey 1949). I have inspected the holotype and paratypes for M. armstrongi, together with over 170 other workers, and consider that this ant and M. whitei are conspecific. The disparity in size does not hold for extended series, and neither does the colour. As an instance of this, 36 workers collected by P. J. M. Greenslade at “Kapunda”, near Nyngan (NSW) include both morphs and a number of forms that are intermediate in colour. This series also includes specimens of varying sizes. Monomorium armstrongi, therefore, becomes a junior synonym in this work.

M. whitei is very closely related to M. bicorne but has proportionately larger eyes. The former species is found mainly in arid, inland Australia, while M. bicorne occurs in wetter coastal areas.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Biology
Heterick (2001) - M. whitei subsists largely or wholly on seeds (Davison 1982). Seeds of 20 plant species are harvested, but chenopods comprise the main part of the diet (Davison 1987). These findings are corroborated by data from specimen labels.

Nomenclature

 *  whitei. Monomorium (Holcomyrmex) whitei Wheeler, W.M. 1915g: 807, pl. 64, fig. 1 (w.) AUSTRALIA. Imai, Crozier & Taylor, 1977: 349 (k.). Heterick, 2001: 378 (q.m.). Combination in Chelaner: Ettershank, 1966: 97; in Monomorium: Taylor, 1987b: 4. Senior synonym of armstrongi: Heterick, 2001: 378.
 * armstrongi. Monomorium (Holcomyrmex) armstrongi McAreavey, 1949: 10, figs. 30-35 (s.w.q.m.) AUSTRALIA. Combination in Chelaner: Ettershank, 1966: 96; in Monomorium: Taylor, 1987b: 2. Junior synonym of whitei: Heterick, 2001: 378.

Worker
Heterick (2001) - HML 3.06-3.57; HL 1.06-2.06; HW 1.06-2.23; CeI 100-114; SL 0.71-1.35; SI 59-67; PW 0.45-0.84 (32 measured).

As for the worker of Monomorium bicorne, but with the following apomorphies.

Head. Frons microreticulate and striolate with combination of appressed setulae and erect and suberect setae. Compound eyes set in anterior half of head capsule, or set at midpoint of each side of head capsule; (viewed laterally); eye large, eye width greater than 1.5x greatest width of antennal scape. Posteromedial clypeal margin level with posterior surface of antennal fossae. Mandibles (viewed from front) strap-like with inner and outer edges subparallel, striate, with piliferous punctures.

Alitrunk. Setulae decumbent and subdecumbent. Mesonotal suture visible externally as faint ridge. Propodeal sculpture present as uniform microreticulation, with few or no striae or costulae; dorsal propodeal face gently convex; propodeal appearance generally as for M. bicorne but some specimens with propodeal processes present on posterior propodeal angles as small denticles or sharp flanges; lobes present as blunt flanges. Propodeal setulae decumbent and subdecumbent.

Petiole and postpetiole. Petiolar spiracle lateral and positioned in pedicel well anteriad of petiolar node. Anteroventral process present as pronounced spur, or slender carina that tapers posteriad. Height-length ratio of postpetiole near 1:1 to near 3:4. Sculpture present in form of microreticulation only.

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

General characters. Colour variable: head orange to dark brown, alitrunk, petiole and postpetiole dark orange to black, gaster light orange to black, appendages orange to dark brown. Worker caste monomorphic but variable in size, with series of intercastes between largest and smallest workers (monophasic allometry).

Queen
Heterick (2001) - HML 5.23-6.13; HL 1.45-1.76; HW 1.73-2.02; Cel 112-124; SL 1.14-1.32; SI 59-67; PW 1.29-1.60 (10 measured).

As for the queen of Monomorium bicorne, but with the following apomorphies.

Head. Compound eyes elliptical, or elongate; much longer than wide; (viewed from front) compound eyes set at midpoint of each side of head capsule; (viewed laterally).

Alitrunk. Propodeal processes always present as small denticles or sharp flanges in this species, and propodeal angle always present.

Petiole and postpetiole. Petiolar spiracle lateral and positioned in pedicel well anteriad of petiolar node. Petiolar node always rugose. Anteroventral process distinct in some individuals as slender carina that tapers posteriad. Sculpture present in form of microreticulation or rugosity; ventral process present and distinct in some specimens.

General characters. Colour either uniformly black with dark red mandibles, or head, alitrunk black, gaster, appendages, mandibles and region around mandibles tawny orange. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

Male
HML 3.98-5.33; HL 0.88-1.32; HW 0.98-1.19; Cel 90-112; SL 0.31-0.36; SI 30-37; PW 1.19-1.45 (10 measured).

As for the male of Monomorium bicorne, but with the following apomorphies.

Head. Head width-mesoscutal width ratio near 1:1 to near 3:4. Compound eyes set posterior of the midline of head capsule.

Alitrunk. Dorsal appearance of mesoscutum striolate and microreticulate.

Wing. Vein m-cu present as an entire vein enclosing first discoidal cell in all specimens seen.

Petiole and postpetiole. Height-length ratio of postpetiole near 1:1.

General characters. Colour black.

Type Material
Heterick (2001) - Syntypes. Monomorium whitei was described by Wheeler (1915b) from four workers taken at Flat Rock Hole, South Australia. One pin, minus the specimen, has been recovered from SAM. The specimen was apparently lost whilst being curated at the ANIC. Label data: Flat Rock Hole, Musgrave Ranges, Central Australia, Capt. S. A. White. I. 4186: “Co-type”. The whereabouts of the other syntypes are unknown.