Myrmoteras brachygnathum

Nothing is known about the biology of .

Identification
Moffett (1985) - Easily distinguished from Myrmoteras ceylonicum and Myrmoteras scabrum by the lack of sculpture on the head and pronotum.

Palpal segmentation 4,3 in all females checked; pilosity consistently sparse, with no more than 15 hairs breaking dorsal margin of trunk in profile.

Bharti and Akbar (2014) - M. brachygnathum belongs to subgenus Myrmoteras. The subgenus is characterized by the labrum having pointed anterior margin with long trigger hairs, relatively shorter mandibles and weakly developed frontal sulcus. M. brachygnathum is easily separated from closely related Myrmoteras ceylonicum and Myrmoteras scabrum by the lack of sculpture on the head and pronotum.

Distribution based on Regional Taxon Lists
Oriental Region: India.

Nomenclature

 *  brachygnathum. Myrmoteras (Myrmoteras) brachygnathum Moffett, 1985b: 26, figs. 19, 22 (w.q.) INDIA.

Worker
Holotype: TL 3.9, HW 0.92, HL 0.85 (CI 109), ML 0.73 (MI 86), SL 0.90 (SI 97), EL 0.56, HFL 0.94 (TWI 20), WL 1.18 mm; paratype worker from same series TL 4.0, HW 0.93 mm, and otherwise virtually identical to holotype. Only a trace of the frontal sulcus is visible. Frontal area not demarcated. Clypeus highly convex, with curvature continuing to lateral margins, as in Myrmoteras ceylonicum but unlike any other species in the subgenus. In M. brachygnathum the clypeus also exceptionally narrow, only 23 to 25% wider than long (greater than 35% for single specimens selected at random from all other species in the genus, including ceylonicum). Palpal segmentation of type 3,3 (in paratype worker 4,3). Mandibles with one to two preapical denticles. Curvature of distal ends of mandible shafts ventrad stronger than described for M. ceylonicum but still relatively weak; bend at penultimate tooth about 30 to 40°.

Pronotum low and evenly convex or slightly flattened; propodeum rounded, summit somewhat higher than mesothorax (virtually level with mesothorax in other species in the subgenus). Metanotal groove conspicuously impressed. Node of petiole tall, with nearly vertical posterior face and very steep, straight anterior face; summit slightly flattened, but lacking the transverse ridges found in M. ceylonicum and Myrmoteras scabrum. Spurs on middle and hind tibiae shorter than in other members of the subgenus, longest with a length of about twice the width of the base of the first tarsal segment.

Head, pronotum and propodeum smooth and polished, lacking sculpture. Mesothorax with two to three narrow longitudinal rugae on sides, weaker longitudinal rugae dorsally. Pilosity considerably reduced in comparison to M. ceylonicum and scabrum, with hairs sparse, 2 to 10 breaking dorsal margin of trunk in profile. Hairs rising 0.08 to 0.10 mm on head, trunk, and gaster. One or no hairs on or near each metathoracic tubercle; node of petiole with two to four hairs. Head and trunk translucent yellowish orange (rugae on mesothorax darker), antennae same but lighter; petiole orange yellow, legs and mandibles lighter orange yellow; gaster very dark orange brown.

Queen
Dealates from type series (one measured; other virtually identical), TL 4.3, HW 1.03, HL 0.92 (CI 112), ML 0.81 (MI 88), SL 0.98 (SI 95), EL 0.63, HFL 1.03 (TWI 20), WL 1.33 mm; very similar in shape and proportions to worker except for more massive trunk; petiole similar but narrower at summit. Trunk entirely smooth and shining, reddish orange; otherwise color same as in workers.

Male
Bharti and Akbar (2014) - TL 3.45-3.53, HW 0.66-0.69, HL 0.71-0.73, CI 92-94, SL 1.04-1.05, ML 0.28-0.29, MI 39-40, SI 152-157, PTL 0.33-0.35, EL 0.33-0.34, HFL 0.99-0.10, TWI 11-12, WL 1.05-1.07, EI 49-50, GL 1.08-1.09, PW 0.60-0.63 (n=2).

Head 0.04 × as long as broad, excluding the large convex compound eyes. The mandible reduced to a triangular peg like structure with apex simple and acute. Frontal sulcus feebly impressed at medial line. Palpi segmentation 3, 2. Antennae slender, 13-segmented; antennal scrobes absent. Mesonotum with reduced notauli; scutellum disc shaped and raised. Legs with claws simple. Gaster elongated; terminalia retracted; pygidium broadly rounded. Petiole node more slender than that of worker. Genitalia with parameres exerted out and prominent.

Sculpture. Head smooth and shiny with reduced frontal sulcus. Pronotum dorsum smooth but, lateral side’s rugulose; mesonotum and metanotum with similar sculpture. Metasoma smooth and shiny.

Vestiture. Head mostly devoid of any erect pilosity, some erect hairs ca 0.14mm along posterior margins of head; hairs on mesosoma similar to that of head; gaster with number of erect hairs.

Colour. Body uniformly dark brown with appendages brown.

Type Material
Holotype. Worker deposited in MHNG from India: Tamil Nadu: Palni Hills, south of Kodaikanal, 2,200 m, 12. XI. 72, #23 [tamisages dans foret degrade avec rhododendrons] (Besuchet and Lobl). Paratypes. One worker and two dealate queens with same locality data and collection number as holotype ( and ).

Etymology
Name derived from Gr. brachys + gnathum, referring to the relatively short mandibles of the females.