Tarsagonum Darlington, 1952

Fedorenko, D. N., 2020, New species of Meleagros and Tarsagonum (Coleoptera: Carabidae: Platynini) from the Oriental region, Russian Entomological Journal 29 (2), pp. 139-147 : 144-145

Tarsagonum Darlington, 1952

Darlington, 1952: 114, 120; Louwerens, 1966: 36.

Type species: Tarsagonum latipes Darlington, 1952 .

DIAGNOSIS.Macropterous, small- to medium-sized (BL 7–11 mm) platynines; body glabrous, black, with mouthparts, antennae and tarsi more or less pale. Head with neck constriction, genae well-developed. Submentum quadrisetose; mentum tooth simple, pointed and more or less sulcate longitudinally, setae very distant. Prosternal process with a thick marginal bead, inclination costate to carinate. Pronotum cordate and rather small. Elytra wide, subquadrate, without basal ridge (at least inside stria 5). Tibiae deeply grooved externally. Tarsi wide, flat, bisulcate, with meso- and metatarsi tricarinate, and asymmetric: tarsomeres 1–3 parallel-sided, in posterior part considerably wider than in anterior (relative to longitudinal axis), tarsomere 4 with anterior lobe as long as the tarsomere proper and posterior lobe indistinct. Body setation as for Meleagros , except as follows: two supra-ocular setae on each side, with posterior seta inserted distinctly behind the level of posterior margin of eye; posterolateral pronotal seta present or not; elytral discal setae not adjoining striae, apical sutural seta missing; profemur glabrous anteriorly, with three posterior setae; metafemur with one anteroventral seta, median. Basal three protarsomeres with ventral pad in male.

GEOGRAPHIC DISTRIBUTION. New Guinea, Borneo, Laos, Southern India.

HABITATS AND HABITS. Collecting circumstances of T. latipes [ Darlington, 1952] and the fact that morphological adaptations are similar in Meleagros and Tarsagonum suggest arboricolous way of life of the adults of the latter genus.

COMMENTS. The genus includes four species hitherto known from very few localities in the Papuan and Oriental regions. Two earlier described species are strictly insular and southern in distribution, and discovery of further two species in mainland South and Southeast Asia extends the genus range much northwards and westwards.

Many features, including such synapotypic characters as tarsal shape and setation, elytral basal ridge obliterate and discal setigerous pores isolated from the striae, seem to support well monophyly of the genus. On the other hand, differences between the Papuan and Oriental species are sufficient to erect a new subgenus for the latter.