Iyotrechus S. Uéno et Naitô, 2009

Karaoğlan, Beliz Bahar, Yekedüz, Emre, Yazgan, Satı Coşkun, Mocan, Eda Eylemer, Köksoy, Elif Berna, Yaşar, Hatime Arzu, Şenler, Filiz Çay, Utkan, Güngör, Demirkazık, Ahmet, Akbulut, Hakan & Ürün, Yüksel, 2022, Contribution to the Knowledge of the Rakantrechus Complex (Coleoptera, Carabidae, Trechini), with Description of a New Subgenus and a New Species of the Genus Nipponaphaenops S. Uéno, 1971 from Northwestern Shikoku, Western Japan, Bulletin of the National Museum of Nature and Science. Series A, Zoology (Zoology) 48 (3), pp. 119-138 : 127-129

publication ID	https://doi.org/ 10.50826/bnmnszool.48.3_119
persistent identifier	https://treatment.plazi.org/id/A95B8783-390E-FFE0-FF12-F9EEFC85C500
treatment provided by	Felipe
scientific name	Iyotrechus S. Uéno et Naitô, 2009
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Subgenus Iyotrechus S. Uéno et Naitô, 2009

Iyotrechus S. Uéno et Naitô, 2009: 246 View in CoL (type-species: Iyotrechus hisamatsui S. Uéno et Naitô, 2009: 248 View in CoL , figs. 1–4, 6–8; genus Iyotrechus View in CoL )

Remarks. As noted in the introduction, Iyotrechus S. Uéno et Naitô, 2009 was originally described as an independent genus in comparison with the genus Ishikawatrechus Habu, 1950 from which the former is distinctly different in the absence of deep transverse furrow on the inclined face of elytral basal peduncle and in the position of the fourth pore of marginal umbilicate series of elytra. However, despite the supposition in the original description that Iyotrechus is probably more closely related to members of the Rakantrechus Complex than to Ishikawatrechus , no key characters that allow the discrimination of Iyotrechus from the other constituents of the Rakantrechus Complex were proposed by us ( Uéno & Naitô, 2009, p. 245–246). Even the range of taxa indicated by the term l Rakantrechus Complexz was not clearly defined in that paper; in any case, Ishikawatrechus was not included in it. Actually Iyotrechus is very similar to subgenera of Rakantrechus ( Figs. 1a–g, j–m View Fig , 2a–d, f–j, m View Fig , 5 View Fig ) but barely discriminated from them as shown in the Identification section below. Based on these, it seems reasonable to regard Iyotrechus as a subgenus of the genus Rakantrechus .

Identification. Within the subgenera of Rakantrechus , Iyotrechus is comparatively similar to Uozumitrechus S. Uéno , and Izushites S. Uéno in the structure of elytral basal parts and in the shape of mentum tooth ( Uéno, 1982b) ( Figs. 2a, c View Fig , 5a–c View Fig ), but different from them in larger body size (BL: 5.55–6.10 mm), in having glabrous genae and in the absence of pronotal postangular setae. On the other side, in having glabrous genae and in the absence of pronotal postangular setae, Iyotrechus is similar to the species of the subgenus Paratrechiama S. Uéno belonging to the species-group of R. nomurai , which is the only one species-group represented in Shikoku within the subgenus (the latter character state is known only in R. (P.) elegans S. Uéno, 1959 of the group; Fig. 5d View Fig ). However, a single representative of Iyotrechus differs from the latter in larger body size (BL: 4.4–5.60 mm, in the nomurai -group), in having simple mentum tooth (bifid in the nomurai -group; Fig. 2d View Fig ), in having only a single discal seta on elytral stria 5, and in having elytral intervals 5–6 which are not distinctly carinate basally (carinate and embracing a round depression between carinae in the nomurai -group; Figs. 3e View Fig , 5d View Fig ).

Taxonomic notes. This subgenus is presently monotypic. In this subgenus (as far as known from the type species), the distance between the pore 1 and 4 of the marginal umbilicate series of elytra (as a value U4–U1) is on average smallest within the genus Rakantrechus (cf. Figs. 5a–f View Fig ); besides, the pore 4 and 5 of the series are relatively close to marginal gutter in this subgenus: the condition closest to that exhibited by the Trechiama species. In a diminutive individual of R. (I.) hisamatsui recorded as one of the problematical specimens in the original description ( Uéno & Naitô, 2009, p. 247, 251), pore 4 of the humeral set is more widely removed from pore 3 than in the type specimens of the same species, though this condition is observed solely at the left side ( Fig. 5b View Fig ).

Geographic range. Northwestern area of Shikoku, southwestern Japan; traversing the ranges of the subgenera Rakantrechus S. Uéno and Izushites S. Uéno ( Fig. 7 View Fig ).

Erratum. Morphometric value of PW/PL given in the original description of Iyotrechus hisamatsui S. Uéno et Naitô, 2009 (= Rakantrechus hisamatsui comb. nov.) is an error. It is to be corrected as follows: (Page 250, line 3–4) For: PW/PL 0.82–1.00 (M 0.93) Read: PW/PL 0.92– 1.00 (M 0.93).