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 : 375

Subgenus Neotichnus Kataev , subgen.n.

Type species: Trichotichnus (Neotichnus) bellorum Kataev, sp.n.

DIAGNOSIS. The adults of this subgenus are recognizable by combination of the following distinctive characters: head large and thick, with fronto-ocular furrows indistinct or shallow and short; ligular sclerite not widened apically; paraglossae wide, separated from ligular sclerite by narrow notch; pronotal basal margin not bordered; elytral intervals impunctate, with distinct short or moderately long transverse meshes; interval 3 without discal pore; prosternum glabrous; metepisternum not longer than wide; and wings reduced to small scales.

DESCRIPTION. Body slightly smaller than average for the genus (6.9–7.3 mm), with comparatively large and thick head and short legs. Coloration of body brown to black, not iridescent on dorsum and not mottled on abdominal sternites. Fronto-clypeal suture superficial or slightly impressed. Fronto-ocular furrows indistinct or shallow and short, not reaching supraorbital furrows. Supraorbital pore markedly removed from supraorbital furrow. Eyes comparatively small and weakly convex, markedly separated from buccal fissure ventrally. Genae glabrous. Mentum and submentum fused. Ligular sclerite not widened apically and with outer angles not protruded laterally, with two ventral setae at apical margin not distant from lateral margins. Paraglossa wide, rounded apically, separated from ligular sclerite by narrow notch (much narrower than paraglossa apically). Pronotal sides more or less sinuate basally, basal angles well defined, at most only blunted at tip, basal margin not bordered. Elytral intervals impunctate, with distinct microsculpture, consisting of short or moderately long transverse meshes, interval 3 without discal pore, parascutellar (abbreviate) striole short, lateral groove flat throughout or with elongate convexity along this groove apically, marginal umbilicate series with or without a gap at middle, consisting of 14– 17 setigerous pores. Thoracic sternites, including prosternum, glabrous. Metepisternum short, not longer than wide, slightly or moderately narrowed posteriorly. Protibia not sulcate. Pro- and mesofemur with no more than four setae along lower margin. Metafemur with two setae at posterior margin. Tarsi dorsally glabrous. Abdominal sternites glabrous, without extra setae and fine pubescence.

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

COMPOSITION AND DISTRIBUTION. The new subgenus includes two new species from Papua New Guinea.

REMARKS. The adults of this subgenus are most similar in the general habitus with a cordate pronotum and in the short metepisternum to those of Amaroschesis and the leptopus group of Trichotichnus s. str., but distinctly differ from them in having the wide paraglossae, the unbordered basal pronotal margin and the glabrous prosternum. Based on the structure of paraglossae and ligular sclerite, Neotichnus subgen.n. is apparently more closely related to the less specialized subgenera Iridessus and Parairidessus , which have these characters in plesiomorphic condition (paraglossae wide and ligular sclerite not widened apically). The narrow paraglossae and ligular sclerite, widened at apex, which are present in Amaroschesis and Trichotichnus s. str., are clearly apomorphic features [ Kataev , 2020]. In the unbordered basal pronotal margin, the new subgenus also differs from both Iridessus and Parairidessus . The species of Parairidessus and most species of Iridessus are also distinct from the new subgenus in having the prosternum with fine short setae, the elytra with a discal setigerous pore on the interval 3, and the metepisternum elongate, its inner margin markedly longer than anterior margin [discal pore is occasionally absent and metepisternum is wider than long only in T. (Iridessus) tonklii Kirschenhofer, 1992 from the Himalaya]. The subgenus Parairidessus is distinguished from Neotichnus subgen.n. by a larger number of setigerous pores (24–34) of the elytral umbilicate series, and the most species of the subgenus Iridessus is distinct from Neotichnus subgen.n. in the finer or indistinct dorsal microsculpture on the elytral intervals. It is worth noting that elytral microsculpture in most species of the genus Trichotichnus consists of the fine transverse lines or indistinct, but this character is variable within the genus; in some Chinese Amarochesis, for example T. oblongus (Tschitschérine, 1906) , T. modestus (Tschitschérine, 1906) and T. obtusicollis Schauberger, 1936 , and in the Indian T. (Parairidessus) perforatus Kataev, 2020, the elytral microsculpture is very distinct, consisting of short transverse meshes. Among Iridessus , somewhat distinct moderately long transverse meshes are present in the Oriental T. parvus Ito, 2001 and T. malayanus Ito, 2001 .

In the general habitus and short fronto-ocular furrows, the species of Neotichnus subgen.n. are somewhat similar to Trichotichnus (s. str.) tolgae Baehr, 1990 , which was described from a single female found in Australia (Queensland). According to the original description [ Baehr, 1990], this species is obviously unrelated to any New Guinean and Australian species. Unfortunately, the original description does not include the information about its ligular sclerite and paraglossae, but in any case T. tolgae , like most species of the nominotypical subgenus, well differs from both species of Neotichnus subgen.n. in having the pronotal base distinctly bordered along entire length, the elytral interval 3 with a discal setigerous pore, the prosternum, metasternum and basal abdominal sternite medially with short pubescence, and the wings fully developed. The taxonomic position of T. tolgae needs further study.

Like Neotichnus subgen.n., the monobasic genus Lyter Darlington, 1968 from New Guinea is characterized by the glabrous prosternum and the elytra without discal pore on the interval 3; in addition, its pronotal margin is vaguely defined and present only laterally. This genus, however, is readily distinguished from Neotichnus subgen.n. in many characters including the ligula with two ventral setae distant from apical margin and situated before preapical constriction of ligula, the pro- and mesofemora along lower margin and metafemora ventrally along the posterior margin with numerous setae, the adhesive vestiture on the male pro- and mesotarsi not arranged in two rows and the metepisternum elongate.

Pronotum without or with indistinct basal border is characteristic of many Harpaloxenus , but the species of the latter taxon differ in having the ventral side mottled, with fine setae at least on the prosternum and on the abdominal sternites medially, the elytra on the lateral intervals distinctly densely punctate, the other intervals more finely punctate, the mentum and submentum completely separated, the metepisternum much longer than wide, etc.

The species of the subgenus Botchrus with unbordered basal margin of pronotum, for example brachypterous T. newtoni Kataev, 2016 from the Philippines, differ in the deeper fronto-ocular furrows.

Interestingly, the species of Neotichnus subgen.n. as well as a single species of the described below Allotichnus subgen.n. are very similar in appearance to the small brachypterous species of the subgenus Bottchrus and even to those of the irvinei group of the genus Chydaeus Chaudoir, 1854 and Nornalupia Kataev, 2002 [see, for example, Kataev , Schmidt, 2002, 2017; Kataev , 2003, 2016], though the latter two genera belong to the subtribe Anisodactylina . This resemblance is a good example of parallel evolution under similar environmental conditions. Notice that two species of the Australian genus Nornalupia , like the two species of Neotichnus subgen.n., differ markedly from each other in punctation on the head and pronotum [ Kataev , 2007].