Perigonini

Baehr, Martin & Reid, Chris A. M., 2017, On a Collection of Carabidae from Timor Leste, with Descriptions of Nine New Species (Insecta: Coleoptera, Carabidae), Records of the Australian Museum 69 (6), pp. 421-450 : 435-436

Tribe Perigonini

The tribe Perigonini includes small, characteristically shaped Carabid beetles which occur on all continents, but are most common in tropical regions ( Csiki, 1931). The mostly small, more or less depressed, Trechus - or Tachys -like beetles are easilY identified bY the elongate, conical terminal palpomeres, short frontal furrows, and the wide, depressed, usually pilose apical marginal channel of the elytra. The affinities of the tribe Perigonini are not fullY understood, but probably they belong to the lachnophorine-odacanthine lineage ( Jeannel, 1948).

The genus Perigona Castelnau, 1835 has been divided into several subgenera (see Lorenz, 2005) which some authors consider genera. One of these subgenera is Trechicus LeConte, 1853 , which is distinguished from Perigona s. str. by the subapical marginal setiferous punctures of the elytra forming a triangle instead of a straight line. The nominate subgenus Perigona includes about 90 described species which are distributed almost worldwide, while the subgenus Trechicus includes about 45 described species most of which occur in the Afrotropical, Oriental, and Papuan-Australian regions, but one of which is a synanthropic species, Perigona nigriceps ( Dejean, 1831) , distributed almost worldwide. However, the number of yet unknown or undescribed species in the genus Perigona may be large, because, apart from Basilewsky’s (1989) revision of the African Perigonini and Baehr’s (2013) revision of a subgroup of Perigona s. str. from the Oriental-Pacific region, no recent comprehensive work has been done on the tribe. The keys of Jedlicka (1964) for the East Asian species, of Darlington (1964, 1968) for the Australian and New Guinean species, and of Andrewes (1929) for the Sumatran species are of some use, although they are outdated, and even were incomplete for the then described species. Moreover, these keys, including those of Darlington (1964, 1968), make no use of genitalic characters. However, the male genitalia in most Perigona species are complex and thus give an excellent tool for differentiation of the externally usually very similar species. Indeed, certain species are barely distinguishable without consideration of the genitalia.

Most Perigona species occur in litter in closed forest; therefore specimens are usually only collected by specialized sampling methods, such as Berlese extraction or sifting ground litter. Most species can fly, so they are also encountered at light and in flight intercept traps. Because such sampling methods have been employed in few areas and moreover, usually rather casually, the taxonomic knowledge of this group is not satisfactory and rather fragmentary.

No species of the genus has previously been recorded from Timor, although P. nigriceps would be expected (present in the examined material) and the related P. litura (Perroud & Montrouzier, 1864) might also be expected as it is a similarly distributed species.