Abacaecus, Allegro & Giachino, 2020

Allegro, Gianni & Giachino, Pier Mauro, 2020, Abacaecus n. gen. walterrossii n. sp., a notable hypogean carabid species from Sierra Leone, Western Africa (Coleoptera, Carabidae, Pterostichinae), Zootaxa 4766 (3), pp. 435-446 : 437

Genus Abacaecus n. gen.

Type species. Abacaecus walterrossii n. sp.

Differential diagnosis. A genus of the tribe Abacetini Chaudoir, 1873 (sensu Will & Park, 2008) distinguished by the combination of second antennomere eccentrically inserted on first, strongly transverse mentum, a parascutellar setigerous pore at base of stria 2, angular base of stria 1 (‘‘scutellar stria’’ auct.) absent, median lobe of aedeagus distally almost rectilinear in lateral view and ostium in dorsal position. It differs from most species of this tribe by body slender and parallel sided, pronotum narrow with markedly protruding fore angles, eyes strongly reduced and not functional.

Description. The description of this monospecific new genus is coincident with the description of the type species, Abacaecus walterrossii n. sp.

Remarks. The attribution of this new genus to the tribe Abacetini sensu Will & Park (2008) is based on a set of characters some of which can be regarded as synapomorphic for Abacetini sensu stricto, such as the eccentrically inserted second antennomere and the strongly transverse mentum, and some others which are recurrent in this tribe, although also present in other pterostichine-grade taxa, such as the single pair of deeply impressed linear basal impressions of the pronotum, the angular base of stria 1 (‘‘scutellar stria’’ auct.) absent, no dorsal puncture on the third elytral interval, the parascutellar elytral puncture at stria two.

Etymology. The genus name results from crasis of the tribal name ( Abacetini ) with the Latin adjective ‘ caecus’, meaning ‘devoid of sight’. The name is masculine.