Iridessus Bates, 1883

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 : 183-187

Subgenus Iridessus Bates, 1883

Argestes LeConte, 1849: 26 [as genus; nomen oblitum, see Bousquet (2008: 328)]. Type species: Harpalus nitidulus Chaudoir, 1843 ), by monotypy.

Iridessus Bates, 1883: 240 [as genus]. Type species: Harpalus relucens Bates, 1973 [= Trichotichnus orientalis (Hope, 1845) ], designated by Tschitschérine (1906). [Designation of Harpalus lucidus Morawitz, 1863 as a type species of this subgenus by Habu (1954) is invalid].

Episcopellus Casey, 1914: 220 [as genus]. Type species: Feronia autumnalis Say, 1823 , by original designation.

Carbanus Andrewes, 1937: 27 [as genus]. Type species: Carbanus flavipes Andrewes, 1937 [= Trichotichnus claripes Lorenz, 1998 ], by monotypy.

Diagnosis. Fronto-ocular furrows shallow, at most deepened only at clypeus, reaching or not reaching supraorbital furrows, occasionally only traces visible. Fronto-clypeal suture superficial or slightly deepened. Ligular sclerite not widened apically, parallel-sided or slightly narrowed before apex, in most members with outer angles slightly prominent laterally. Paraglossa moderately wide, rounded apically, separated from ligular sclerite by narrow notch (much narrower than paraglossa apically). Elytra with lateral groove flat throughout, without elongate convexity along this groove apically. Elytral marginal umbilicate series with more or less wide gap at middle, occasionally with one intermediate pore in gap, consisting of 15–20 setigerous pores. Abdominal sternites glabrous, without extra setae. Abdominal sternite VII with two pairs of marginal setigerous pores in both sexes. Gonocoxite with one short seta on ventral out- er edge at base (in some members also on dorsal outer edge) or without seta. Median lobe of aedeagus with apical orifice in dorsal position or shifted to left.

Composition. This subgenus includes 25 described species. Most of them are distributed in the Oriental region and the southeastern Palaearctic, but a few are also known from the Australian and Nearctic regions.

Remarks. Iridessus was originally erected as a genus for two species: Harpalus lucidus Morawitz, 1863 from Japan and H. relucens Bates, 1873 [= T. orientalis (Hope, 1845) ] from Japan and China. Iridessus was cited as a separate genus by many subsequent authors ( Tschitschérine, 1897b, 1900, 1901, 1906; Jacobson, 1907; Andrewes, 1919; Csiki, 1932; Jedlička, 1954) until Habu (1954) synonymised it with Trichotichnus . Several Oriental and Australian species, included now in the subgenus Iridessus , were described within the genus Carbanus ( Andrewes, 1937, 1947; Louwerens, 1962). Darlington (1968: 51) included Carbanus in Trichotichnus although noted that this taxon is rather distinct in its appearance and “may eventually be separated from Trichotichnus ”. More recently, Noonan (1976, 1985), Lorenz (2005) and Bousquet (2012) considered Carbanus as a synonym of Trichotichnus s. str. Japanese authors (for example, Habu, 1961, 1973; Ito, 2001, 2002, 2014) treated the Palaearctic and Oriental species of Iridessus , including the type species of the latter, as the members of the orientalis group of the nominotypical subgenus without reference to Carbanus . Ball & Bousquet (2000), Bousquet (2012) and Kataev & Wrase (2017) considered Iridessus as a separate subgenus. In the latter work, Carbanus was considered as a synonym of Iridessus since their diagnostic characteristics are the same. Carbanus flavipes Andrewes, 1937 (= T. claripes Lorenz, 1998 ) from Java, the type species of Carbanus , is at most only a geographical form of T. szekessyi ( Jedlička, 1954) which was originally described as Iridessus and treated as a member of the orientalis group by Ito (2001).

The subgenus is well defined morphologically. In addition to the features listed in the diagnosis, it is also characterised as follows: body comparatively small (4.8–8.8 mm), wide and flat, Amara (Celia) or Harpalus -like, with pronotal basal angles in many species more or less rounded at apex; genae narrow to moderately wide, in most species narrower than antennomere 2; protibia not sulcate; and median lobe of aedeagus in many species with more or less developed apical capitulum having flanges both dorsally and ventrally. Iridessus differs from Trichotichnus s. str. in somewhat wide, rounded apically paraglossae which are separated from ligular sclerite by narrow notches.

Trichotichnus (Iridessus) tonklii Kirschenhofer, 1992

( Figs 17–23)

Trichotichnus (s. str.) tonklii Kirschenhofer, 1992: 39 .

Type material examined. Holotype. Male, “Shabru, 1500–2200 m, 19.IV.1978, Nepal, Tonkli P. // Holotypus // Trichotichnus tonklii n. sp., det. Kirschenhofer, 91” ( NHMW) . Paratype. Female, same data as for holotype but labelled “ Paratypus ” ( NHMW) .

Additional material examined. Nepal, Bagmati: 5 males, 2 females, Langtang National Park, Dhunche- Shin Gompa , 28°06.63ʹN 85°20.47ʹE, 1950–3250 m, 1.V.2000, A. Konstantinov, S. Lingafelter & M. Volkovitsh leg. ( ZIN, cWR) ; 2 females, “ Rasuwa Distr., Langtang Tal zw. Syabru Bensi u. Ghora Tabela ”, 1600–3000 m, IV.1998, St. Roth leg. (cJS) ; 1 male, 1 female, Langtang National Park, Ghora Tabela , 3000 m, 13.V.1988, S. Bily leg. ( NHMB) ; 2 males, 2 females, Langtang Valley, Khangiung – Sharpugaon , 2225–2600 m, 16.IX.1984, P. Beron & St. Andreev leg. ( NMNHS) ; 4 males, Langtang Valley, Bamboo Lodge – Lama Hotel, 1900–2400 m, 15.IX.1997, Ahrens leg. (cJS, ZIN) .

Diagnosis. Apterous species markedly differing from other members of Iridessus in very short metepisternum which is markedly wider than long.

Description. Body length 6.3–8.1 mm, width 2.6–3.5 mm. Habitus as in Fig. 17. Piceous, shiny on dorsum, with palpi, antennae and legs brownish; femora distinctly infuscate. Fronto-clypeal suture and fronto-ocular furrows shallow. Genae moderately wide, about as wide as antennomere 1. Left mandible truncate or blunted at tip. Mentum ( Fig. 18) completely fused with submentum; ligular sclerite almost parallel-sided, with outer angles slightly prominent laterally; paraglossa moderately wide, rounded apically, separated from ligular sclerite by narrow notch. Pronotum very finely punctate basally, with basal angles obtuse, slightly blunted at tip. Elytra with lateral groove narrow and flat throughout, without elongate convexity along this groove apically. Elytral marginal umbilicate series with a short gap at middle, consisting of 15–18 setigerous pores (seven or eight pores in anterior group and eight to ten such pores in posterior group). Metepisternum markedly wider than long. Profemur anteriorly with two setigerous pores in basal third of lower margin. Metafemur ventrally with two setigerous pores at posterior margin. Tarsi dorsally glabrous. Mesotarsomere 1 of male with two very small adhesive scales just at apex. Abdominal sternite VII with two pairs of marginal setigerous pores in both sexes. Gonocoxite ( Figs 19, 20) with a very short (hardly recognisable) seta on both ventral and dorsal outer edges basally. Median lobe of aedeagus ( Figs 21–23) with apical orifice shifted to left, without sclerotised elements in inner sac.

Distribution. This species is endemic to the Langtang Valley in Central Nepal (Bagmati Province) where it occurs at altitudes of 1500–3250 m.

Remarks. A single known species of Iridessus with highly reduced hind wings. It was described as a member of the nominotypical subgenus, without reference to the orientalis group, Iridessus or Carbanus , as closely related to T. (s. str.) aquilo Andrewes, 1930 . In the general habitus with shallow fronto-ocular furrows and transverse metepisternum, it reminds species of Amaroschesis , but in the structure of labium and other characters it should be included in the subgenus Iridessus .

Figs 24–28. Trichotichnus (Iridessus) autumnalis ( Say, 1823) . 24, labium; 25, gonocoxite; 26, laterotergite, gonosubcoxite and gonocoxite; 27, 28, median lobe of aedeagus. Ventral view (24, 26), lateral view (25, 27), and dorsal view (28). Scale bar: 0.5 mm.