Kataev, Kataev, 2022

Kataev, B. M., 2022, Description of two new subgenera of Trichotichnus, with new brachypterous species from New Guinea and Sumatra (Coleoptera: Carabidae), and notes on three previously described species, Russian Entomological Journal 31 (4), pp. 373-384 : 380-382

Subgenus Allotichnus Kataev , subgen.n.

Type species: Trichotichnus (Allotichnus) beroni Kataev, sp.n.

DIAGNOSIS. The adults of this subgenus are recognizable by combination of the following distinctive characters: head very large and thick, with fronto-ocular furrows vaguely defined; ligular sclerite widened apically; paraglossae narrow, separated from ligular sclerite by wide notch; pronotal sides without lateral seta; basal margin with incomplerte border; elytral intervals impunctate, with distinct moderately long transverse meshes; interval 3 without discal pore; prosternum with setae; metepisternum wider than long; wings reduced to small scales; last visible abdominal sternite of both sexes with one pair of marginal setae.

DESCRIPTION. Body smaller than average for the genus (5.2–5.5 mm), with very large and thick head and short legs. Coloration of body brown, not iridescent on dorsum and not

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mottled on abdominal sternites. Fronto-clypeal suture shallow. Fronto-ocular furrows short, vaguely defined. Supraorbital pore markedly removed from supraorbital furrow. Eyes weakly convex, markedly separated from buccal fissure ventrally. Genae glabrous. Mentum and submentum fused. Ligular sclerite markedly widened apically, with two ventral setae at apical margin slightly distant from lateral margins. Paraglossae narrow, separated from ligular sclerite by wide notch (about as wide as paraglossae apically). Pronotal sides without lateral seta, sinuate basally, basal angles well defined, basal margin vaguely bordered laterally. Elytral intervals impunctate, with distinct microsculpture consisting of moderately long transverse meshes, interval 3 without discal pore, parascutellar striole short, lateral groove flat throughout, marginal umbilicate series with a gap at middle, consisting of 12–15 setigerous pores. Prosternum with scattered fine and short setae. Metepisternum wider than long. Protibia not sulcate. Pro- and mesofemur with one or two setae along lower margin; metafemur with two setae at posterior margin. Tarsi dorsally glabrous. Abdominal sternites glabrous, without extra setae; last visible abdominal sternite of male and female with one pair of marginal setae.

ETYMOLOGY. The subgenus name is a combination of the Greek allo meaning “other, different”, and a part of the name of the carabid taxon Trichotichnus .

COMPOSITION AND DISTRIBUTION. This new subgenus includes only Trichotichnus beroni sp.n. from Sumatra ( Indonesia).

REMARKS. Though the single member of this new subgenus is similar to species of Neotichnus subgen.n. in general habitus and some distinctive structural characters (for example, short metepisternum, vaguely defined fronto-ocular furrows, completely fused mentum and submentum, elytra without discal pore), in my opinion, these subgenera, are not closely related since their resemblance is apparently convergent and based on adaptation to similar environmental conditions. The two subgenera are significantly distinguished from each other by the structure of the ligular sclerite and paraglossae, and based on this character, Allotichnus subgen.n. is more similar and obviously more related to Trichotichnus s. str. and Amaroschesis . The subgenera Allotichnus subgen.n. and Amaroschesis are particularly similar in having a transverse metepisternum, though this character appears to have arisen independently in these taxa, which are most likely descended from different ancestors with an elongate metepisternum and fully developed wings.Two characters of Allotichnus subgen.n. (the absence of setigerous pore on the pronotal lateral margins and the presence of one pair of marginal setigerous pores on the last visible abdominal sternite of male and female) are very rare among harpalines and are probably unique within Trichotichnus ; they should be treated as apomorphies for this subgenus. In the harpalines, the pronotum without lateral setigerous pore is known among Chydaeus , for example in the Chinese Ch. asetosus Kataev et Kavanaugh, 2012; one pair of marginal setigerous pores on the last visible abdominal sternite of female occurs, for example in Allocinopus Broun, 1903 and in many species of Hyphaereon MacLeay, 1825 . All known species of Trichotichnus s. str. and Amaroschesis also differ from the single species of this new subgenus in larger body size, with length of more than 6.0 mm.

Since the distinctive features of this taxon are very unusual for Trichotichnus , further studies may show the need to treat it as a separate genus.