Trichotichnus (Parairidessus), Kataev, 2020

Kataev, B. M., 2020, Description of a new subgenus of Trichotichnus (Coleoptera: Carabidae), with two new species from the Western Ghats (India), and remarks on other subgenera, Zoosystematica Rossica (China) 29 (2), pp. 172-194 : 174-175

Subgenus Parairidessus subgen. nov.

Type species: Trichotichnus saluki sp. nov.

Diagnosis. Fronto-ocular furrows deepened at clypeus, shallow posteriorly, reaching supraorbital furrows. Fronto-clypeal suture superficial or slightly deepened. Ligular sclerite markedly narrowed apically, truncate at apex, with two ventral setae just at apical edge. Paraglossa moderately wide, rounded apically, separated from ligular sclerite by narrow notch (much narrower than paraglossa apically). Elytra with lateral groove flat throughout, without distinct elongate convexity along this groove apically. Elytral marginal umbilicate series without any gap at middle, consisting of 24–34 setigerous pores. Abdominal sternites glabrous, without extra setae. Last visible ( VII) abdominal sternite with two pairs of marginal setigerous pores in both sexes.

Etymology. The subgenus name is a combination of the Greek para meaning “near”, and the name of the carabid taxon Iridessus .

Composition. The new subgenus includes two new species from the Western Ghats, India.

Remarks. In the combination of the distinctive characters, Parairidessus subgen. nov. is most similar to Iridessus but clearly differs in having the ligular sclerite markedly narrowed apically, the elytral marginal umbilicate series without gap at middle, and the body more convex and elongate, more similar to that of the members of Trichotichnus s. str. The new subgenus is also characterised by: dorsum, including head, pronotum and elytra, micropunctate or finely punctate, glabrous; genae narrow, eyes ventrally almost reaching buccal fissure; mentum and submentum fused; palpi with rather long dense setae; metepisternum markedly longer than wide, strongly narrowed posteriorly; protibia not sulcate dorsally; metafemur ventrally with two or three setae at posterior margin and without setae at anterior margin; gonocoxite basally with tiny, hardly recognizable spine at both ventral and dorsal outer edges or only on ventral edge; apical orifice of aedeagus in dorsal position, prolonged to basal bulb; terminal lamella thin, with acute ventral flange at apex; and inner sac with numerous small and moderately sized spines.

Each of the two included species has its own very peculiar distinctive features unusual for Trichotichnus . The median lobe of T. perforatus sp. nov. is sclerotised only laterally, leaving ventral side widely membranous. This character is unusual not only for Trichotichnus but also for most oth- er Harpalini , being found only in Dicheirotrichus Jacquelin du Val, 1857 , some representatives of Bradycellus Erichson, 1837 (both these genera belong to the subtribe Stenolophina ), and, according to Noonan (1973), present in one species of Allocinopus Broun, 1903 of the subtribe Anisodactylina (other species of this genus have the ventral side completely sclerotised). In T. saluki sp. nov., the tarsi are densely setose on dorsal side and the pronotal apical angles have several distinct setae. In most Trichotichnus , tarsi and pronotal apical angles are glabrous; dense tarsal setation is present only in a few species, for example, T. (s. str.) longitarsis Morawitz, 1863 , while sparse and short setae are observed in some species of Iridessus , Botthrus and Amaroschesis . In T. perforatus sp. nov., the tarsi are glabrous dorsally; the setae in pronotal apical angles are present, but much shorter and vary considerably in length up to nearly indistinct in some specimens. Similar extremely short setae are present in some other species of Trichotichnus unrelated to each other, for example, T. (s. str.) coruscus (Tschitschérine, 1895) , T. (Iridessus) szekessyi ( Jedlička, 1954) , T. (I.) parvus Ito, 2001 , some Bottchrus , and also in many other Harpalini , for example, some Lampetes Andrewes, 1940 , Dioryche MacLeay, 1825 , Parophonus Ganglbau- er, 1892, and even Stenolophus Dejean, 1821 . The presence of one or several longer setae in pronotal apical angles, as in Trichotichnus saluki sp.nov., is either an individual characteristic of some species, for example, Harpalus (Cryptophonus) schaumii Wollaston, 1864 ( Kataev, 2012), or a common character (synapomorphy) of several genera, including those of the Ophoniscus -complex ( Kataev, 2005). Although differences between T. saluki sp. nov. and T. perforatus sp. nov. in the aedeagi and the pronotal and tarsal setation are considerable, the new subgenus seems to be a natural group on the basis of the unique combination of the characters listed in the diagnosis. Many other common characters observed in these two species, including similar habitus, and their distribution in one geographical area also argue for their close relationship. Peculiar structure of the aedeagus of T. perforatus sp. nov., as well as the distinct setae in the pronotal apical angles and the densely setose tarsi of T. saluki sp.nov. are regarded as autapomorphies for these species.

The new subgenus and Iridessus (both with shallow fronto-ocular furrows, a narrow ligular sclerite and wide paraglossae) appear to be basal taxa within Trichotichnus . The nominotypical subgenus, Amaroschesis and Bottchrus seem to be more advanced because they have these characters modified: the former two subgenera have narrow paraglossae and the ligular sclerite widened in most species, and the latter subgenus has deep fronto-ocular furrows.