Odontomachus sumbensis

Little is known about the biology of .

Identification
Brown (1976) - As befits its relatively isolated source island, situated below the main Sunda chain, O. sumbensis is the most distinct member of its subgroup. The coloration; with red head, blackish body and yellow legs, is much like that of Odontomachus floresensis, but the reduced sculpture is quite different. The shape of the petiolar node is also different, being thicker and more convex (more dome-like), with the apical spine shorter in sumbensis than in floresensis, and the preapical series of mandibular teeth are somewhat larger in sumbensis. This species and floresensis could well be only extreme insular variants of Odontomachus papuanus or one of the other infandus group species. This group needs much more study on New Guinea.

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

Nomenclature

 *  sumbensis. Odontomachus sumbensis Brown, 1976a: 166 (w.) INDONESIA (Sumba I.).

Worker
Holotype: TL 12.8, HL 3.03, HW ( across vertex) 1.93, HW (across ocular prominences) 2.22, ML 1.64, scape L 2.84, eye L 0.51, WL 4.10 mm; CI 64, MI 48, SI 115.

Paratypes, 7 workers from type locality (Mao Marru) and 1 from Kananggar, Sumba; only 2 were measured in detail, and the measurements are given combined with those of the holotype, which was the largest of all the specimens in the type series.

A relatively broad-headed member of the infandus group (palpal formula 4,4) with apical, intercalary and subapical teeth of mandibles normally acute, the subapical tooth longconical, and a strong preapical series of 7-10 teeth on the inner margin; of these preapical teeth, the first and second counting away from apex toward base are large, triangular, the second usually largest (in one specimen, a denticle exists between these two teeth), and from there decreasing in size to the base of the mandible. Antennal scapes when held straight back surpassing the posterior border by an amount about equal to the length of the pedicel (first funicular segment), or by a little more in the smallest specimen. Second funicular segment much longer than pedicel and subequal to third; beyond the third, segments decreasing slightly in length toward apex; apical segment only slightly longer than second.

Trunk rather slender; pronotum with a fairly long, tapered anterior cervical portion and a gently convex, sloping anterior face. Mesonotum as seen from the side tilting upward cephalad, with a narrowly rounded anterior edge projecting upward rather sharply above posterior margin of pronotum. Mesonotal profile almost straight (feebly convex) but seen from above it is convex from side to side. Metanotum distinct, impressed slightly but distinctly below level of propodeal dorsum. Side-view profile of propodeal dorsum long, straight to very feebly concave.

Petiole broad and as seen in side view, thick from front to rear, with a very brief anterior peduncle ; anterior face forming one long, sloping convexity from peduncle to root of apical spine, where the profile changes to a very slight concavity from root to apex of the fairly long, sharp, posteriorly inclined spine. Posterior profile of node bisinuate; concave at root of spine, convex at a posterior, slightly swollen portion of the upper posterior nodal face, and below this nearly vertical, or even slightly concave to near base. Seen from the rear, the swollen upper rear face of the node is feebly sulcate vertically on the midline. Thus the lateral outline of the petiole is much like that of O. biumbonatus, but with the apical spine back-tilted instead of erect. Gaster high, strongly vaulted above, the first tergum not flattened or impressed, but strongly convex in both directions; tergum II with a well developed stridulatory file on the acrotergite, behind this a feeble transverse impression, after which the tergum is broadly convex in both directions.

Sculpture of the usual striate type on the head and trunk, but the striation effaced and replaced on the vertex and sides of head, and posterior half of disc of pronotum, by a smooth or nearly smooth, shining surface. Striation weak behind ocular ridges, distinct in extraocular furrows, but not extending back beyond temporal ridges, nor below level of eyes on sides of head. Cheeks from in front of eyes to mandibular insertions nearly or quite smooth. Cervix and front half of pronotal disc finely transversely striate, striae becoming weaker caudad, and finally effaced completely or nearly completely on posterior disc, where in some lights on some specimens, feeble traces of transverse striation can still be seen on an essentially smooth and shining convex surface. Rest of trunk transversely striate, vertically striate on sides, except middle and most of posterior part of mesopleura, which are smooth and shining. The above smooth areas mostly bear scattered punctures. Petiolar node and all normally exposed surfaces of gaster glassy-smooth and shining.

Pilosity, and especially pubescence, in generally weakly, developed (some specimens rubbed). The usual long middorsal cephalic pair, 3-0 fine, erect hairs on underside of head near buccal opening, 0-6 fine, erect hairs in pronotum, 1-5 short, erect hairs near posterior border of gastric tergum I, and a rather sparse complement of long, fine hairs on underside of gaster and on dorsum of second and apical gastric segments. Pubescence appressed to subappressed, fine, nearly obsolete, except on legs ; especially reduced and sparse on node and gaster, where almost invisible in most lights.

Head ferruginous red; trunk, petiole and gaster piceous (perhaps nearer black in life or in fresh specimens; types probably somewhat faded), pronotum more or less suffused with reddish; legs yellow; antennae light reddish brown; funiculi yellowish brown.

Type Material
Holotype and 7 paratypes (MCZ, -London ) from Mao Marru, 450 m, Sumba Island, Indonesia; and a single paratype (MCZ) from Kananggar, 700 m, Sumba, all collections by K. Dammerman, May 1925.

References based on Global Ant Biodiversity Informatics

 * Brown W. L., Jr. 1976. Contributions toward a reclassification of the Formicidae. Part VI. Ponerinae, tribe Ponerini, subtribe Odontomachiti. Section A. Introduction, subtribal characters. Genus Odontomachus. Stud. Entomol. 19: 67-171.