Anillomyrma tridens

Bolton (1987) tentatively suggested that A. tridens is nomadic.

Identification
Eguchi et al. (2009) - Body sculpture absent except for hair-pits, which are most conspicuous on head and promesonotum; dorsum of head, promesonotum and gaster relatively densely covered with short suberect to decumbent hairs. Head in full-face view roughly rectangular, longer than broad; mandible with three large sharp teeth. Apical and preapical teeth close together, separated by a diastema from 3rd tooth; 3rd much larger than 2nd; antennal scape short, reaching only 7 / 10 - 3 / 4 of distance from anterior margin of clypeus to posterior margin of head; apical antennal segment more than 3 times as long as preapical segment. Dorsum of mesosoma in lateral view flat. Dorsum and posterior slope of propodeum in lateral view forming rounded outline. Petiolar peduncle in lateral view relatively slender.

Anillomyrma tridens is morphologically very similar to Anillomyrma decamera. The only conspicuous morphological characters separating the two species are as follows: head slightly longer than broad, masticatory margin of mandible of A. tridens having 3 distinct teeth as mentioned by Bolton (1987) (but very small 4th tooth rarely present); the 3rd tooth of A. tridens much larger than 2nd; posterior slope of propodeum in lateral view ex-panding posterodorsad more strongly in A. tridens than in A. decamera; petiolar peduncle in lateral view more slender in A. tridens than in A. decamera.

Distribution
Malaysia: Sarawak.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia.

Biology
Bolton (1987) - A. tridens was discovered in Sarawak crossing a small forest path by means of a covered runway in the topsoil. The runway was very conspicuous where it crossed the path and consisted of a narrow shallow groove in the soil which was covered by a canopy of small soil particles, concealing the ants moving along inside the tube thus formed. On disturbing the soil of the runway large numbers of minute yellowish ants poured out to investigate. Handling these tiny ants proved to be a mistake as they use their stings freely and, though minute, they are capable of penetrating the skin and delivering a painful sting out of all proportion to the size of the ant. The ant runway was revisited a few hours later and workers were still moving along within though no trace of sexuals or brood could be found. I am unable to say whether this movement represented a nest transfer or whether A. tridens is nomadic, but the ant runway was not on the forest path the day before its discovery and was deserted the day after, and shortly after that was washed away by a downpour. The site of the runway was checked periodically for the next couple of weeks but the ants never returned.

Castes
Known only from the worker caste.

Nomenclature

 *  tridens. Anillomyrma tridens Bolton, 1987: 274, figs. 1, 4 (w.) BORNEO. See also: Eguchi, Bui, et al. 2009: 36.

Worker
Holotype and 10 paratype workers: CI 88 - 90, HL 0.37 - 0.39, HW 0.33 - 0.36, PW 0.24 - 0.25, SI 57 - 60, SL 0.21 - 0.23, WL 0.35 - 0.39.

With habitus as in Figs 1, 4, and with characters of generic diagnosis. Mandibles with three large sharp teeth, which are darker in colour than the remainder of the body. Apical and preapical teeth close together, separated by a diastema from the third (basal) tooth, the third tooth shallowly curved towards the apex of the mandible. Antenna. scapes short (SI 60 or less), slightly shorter than the funiculus which measures ca 0.36 in the holotype. Of the funicular segments the first is ca 0.06, the annular segments 2-6 measure only 0.06 together, and the relatively large club is 0.24 (the club is longer than the scape). Pronotal humeri very broadly rounded in dorsal view, the dorsal alitrunk pinched in at the metanotal line. Petiole node longer than broad in dorsal view, the postpetiole slightly broader than long. All dorsal surfaces of head and body with abundant short soft fine standing hairs; the legs, scapes and sides of head with similar hairs which project freely. Sculpture absent except for hair-pits, which are most conspicuous on the head and pronotum. Colour very pale yellowish white, extensively depigmented.

Type Material
Holotype worker: East Malaysia: Sarawak, 4th Division, Gunong Mulu Nat. Park, RGS Exped., Long Pala, lowland rain forest in sandy soil, leg. B. Bolton, 11.X.1977 ; para-types: workers with same data as holotype (BMNH,, , NMB). Fifteen paratypes (personally donated to by B. Bolton) and 9 paratypes (MCZC) examined.