Chelaner falcatus

Monomorium falcatum is currently known only from material collected by J. W. Armstrong in October 1946 (the holotype and paratypes), and again on l.ix.l964. The collector stated on a label accompanying the second series that they came from the “type colony”(!) Various collectors in and around Nyngan have made many subsequent collections of ants, and the absence of M. falcatum from such collections suggests that it is very rare and possibly highly localised. Nothing is known of its biology. (Heterick 2001)

Identification
Heterick (2001) - A member of the falcatum group. Of the Australian Monomorium, only Monomorium elegantulum has an appearance similar to M. falcatum, and the latter is much smaller (HML <2 mm).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  falcatum. Schizopelta falcata McAreavey, 1949: 15, figs. 42-47 (w.q.m.) AUSTRALIA. Combination in Chelaner: Ettershank, 1966: 96; in Monomorium: Taylor, 1987b: 2. See also: Heterick, 2001: 380.

Worker
Heterick (2001) - HML 2. 72-2.91; HL 1.09-1.23; HW 1.07-1.13; Cel 92-97; SL 0.38-0.65; SI 52-58; PW 0.56-0.61 (5 measured).

Head. Head square or rectangular; vertex slightly concave; frons smooth and shining with combination of minute setulae in evenly spaced pits, and sparse erect and suberect setae. Compound eyes elliptical; (viewed from front) compound eyes set in anterior half of head capsule; (viewed laterally) compound eyes set anterior of midline of head capsule; eye large, eye width greater than 1.5 x 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. Longest lateral anterior clypeal setae short, not reaching dorsal margin of closed mandibles. Posteromedial clypeal margin situated between anterior and posterior surfaces 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: three; mandibles (viewed from front) strap-like with inner and outer edges subparallel, striate, with piliferous punctures; basal tooth not enlarged; basal angle indistinct; apical and basal mandibular margins meeting in curve.

Alitrunk. Promesonotal sculpture present in form of microreticulation on mesopleuron; promesonotal dorsum smooth and shining, with evenly spaced foveae; dorsal promesonotal face evenly convex; erect and suberect promesonotal setae absent; setulae decumbent and subdecumbent. Mesonotal suture visible externally as faint ridge. Metanotal groove present as feebly impressed furrow between promesonotum and propodeum. Propodeal sculpture present as uniform microreticulation, with few or no striae or costulae; 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 sharp spines; lobes present as blunt flanges. Propodeal angle present; length ratio of dorsal face to declivitous face near 2: l to near 4:3; declivitous face of propodeum flat. Erect and suberect propodeal setae absent or very sparse; propodeal setulae absent. 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 tumular and inclined anteriad; sculpture present in form of microreticulation. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 4:3, or near l: l. Anteroventral process present as pronounced spur, or slender carina that tapers posteriad. Ventral lobe always absent. Height ratio of petiole to postpetiole near 4:3; height-length ratio of postpetiole near 4:3. Sculpture present in form of microreticulation. Ventral process present and distinct.

Gaster. Pilosity of first gastral tergite consisting entirely of well-spaced appressed setulae.

General characters. Colour orange: an exception is a paratype ergatoid/intercaste, which has a black head capsule with an orange strip near the occiput, black fore coxae, and infuscation of venter of alitrunk. Worker caste monomorphic.

Male
Heterick (2001) - PW 0.69. (McAreavey (1949) mentions that the length of the intact specimen was 3.2 mm.)

Alitrunk. Mesoscutum in profile convex anteriad, thereafter flattened; dorsal appearance of mesoscutum reticulate; mesoscutal pilosity cons1stlng of long, dense setae. Parapsidal furrows present, but difficult to see because of surrounding sculpture; notauli absent. Axillae separated by distance of 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 present; petiolar node rugose; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 3:4. Anteroventral process present as a blunt spur; ventral lobe absent. Height-length ratio near 1 :2; sculpture present in form of microreticulation; ventral process present and distinct.

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

General characters. Colour chocolate.

Type Material
Heterick (2001) - Holotype. Worker, New South Wales, Bogan R., J. Armstrong ( — as “Schizopelta falcata”). Paratypes. New South Wales: Ergatoid/intercaste and male (lacking head) on same pin as holotype (ANIC); 2 workers, Bogan R. (MV- as “Schizopelta falcata”, T -15254).