Trichotichnus (Iridessus) nitidulus (Chaudoir, 1843)

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 : 188-190

Trichotichnus (Iridessus) nitidulus

( Chaudoir, 1843), nom. resurr.

(Figs 29–38)

Harpalus nitidulus Chaudoir, 1843: 788 .

Harpalus fulgens Csiki, 1932: 1162 (non Dejean, 1829), unnecessary substitute name for Harpalus nitidulus Chaudoir, 1843 (see Remarks below).

Type material examined. Lectotype (designated by Lindroth, 1968: 811). Male, “Ex Musaeo Chaudoir // Lectotypus nitudulus Chaud. design. Lindroth // fulgens Cki. ( nitidulus Chd. ) det. Lindroth 66)”, “G.R. Noonan 02–87” ( MNHN).

Additional material examined. More than 80 specimens from USA collected in Illinois, Indiana, Pennsylvania, New Jersey, Maryland, District of Columbia, West Virginia, Virginia, Kansas, Tennessee, Texas, Louisiana, Alabama, and Florida ( FMNH, UASM, ZIN, ZMUC) .

Diagnosis. Easily recognised among the other members of Iridessus by the following characters: head without or with very short and fine fronto-ocular furrows, genae moderately wide, pronotum impunctate, parascutellar pore absent, and tarsi dorsally with very short and sparse setae.

Description. Body length 6.1–7.1 mm, width 2.6–2.9 mm. Dark brown to black, shiny, with epipleurae, palpi, antennae and legs brownish yellow. Fronto-clypeal suture very fine, superficial. Fronto-ocular furrows lacking or only slightly visible (Figs 29, 30). Genae moderately wide, about as wide as antennomere 1. Left mandible truncate at tip. Mentum (Fig. 31) separated from submentum by complete suture; ligular sclerite narrow, very slightly widened apically; paraglossa moderately wide, separated from ligular sclerite by narrow notch. Pronotum (Figs 32, 33) impunctate or with a few fine punctures in basal foveae, with round- ed basal angles. Parascutellar striole more or less reduced. Parascutellar pore absent. Elytra with lateral groove narrow and flat throughout, without elongate convexity along this groove apically. Elytral umbilicate series with more or less wide gap medially, consisting of six to eight setigerous pores in anterior group and of eight to ten such pores in posterior group. Metepisternum longer than wide. Profemur anteriorly with two setigerous pores in basal third of lower margin. Metafemur ventrally with two setigerous pores at posterior margin. Tarsi dorsally covered with very short and sparse setae (Figs 34, 35). Mesotarsomere 1 in male short, with reduced (occasionally absent) vestiture. Metatarsomere 1 elongate, but shorter than metatarsomeres 2 and 3 combined. Abdominal sternite VII with two pairs of marginal setae in both sexes. Gonocoxite (Fig. 36) without seta on outer margin. Median lobe of aedeagus (Figs 37, 38) with apical orifice slightly shifted to left Figs 29–42. Trichotichnus spp. 29–38, T. (Iridessus) nitidulus ( Chaudoir, 1843) . 39, T. (s. str.) vicinus (Tschitschérine, 1897) ; 40, T. (s. str.) anthracinus Landin, 1955 ); 41, T. (s. str.) vulpeculus ( Say, 1823) ; 42, T. (s. str.) laevicollis (Duftscmid, 1812) . Right half of head (29, 30); labium, ventral view (31); right half of pronotum (32, 33); metatarsus (34, 35); laterotergite, gonosubcoxite and gonocoxite, ventral view (36); median lobe of aedeagus, dorsal view (37); the same, lateral view (38); ligular sclerite and paraglossae, ventral view (39–42). Scale bars: 0.5 mm (A: 29, 30, 32, 33; B: 31, 34–42).

and with apical capitulum prominent both dorsally and ventrally. Inner sac with several groups of moderately sized spines and with one larger spine medio-dorsally.

Distribution. Southeastern Canada (southernmost Ontario) and the eastern United States south from Pennsylvania and Massachusetts to Florida and Texas ( Noonan, 1991; Bousquet, 2012).

Remarks. The species was for a long time considered as a representative of the genus Harpalus (for example, Lindroth, 1968; Noonan, 1991; Bousquet & Larochelle, 1993; Lorenz, 2005) until Kataev (in Ball and Bousquet, 2000) transferred it to the genus Trichotichnus based on the following combination of characters typical for the latter genus and separating it from Harpalus : the paraglossae glabrous, elytral microsculpture transverse, metafemur ventrally with two setigerous pores at posterior margin, metatarsomere 1 somewhat elongate and head with fronto-ocular furrows in at least some specimens (while indistinct in many others; similar character state is observed also in some Trichotichnus , for example, T. lucidus ). Based on structure of labium and oth- er features, T. nitidulus is included in the subgenus Iridessus . Trichotichnus nitidulus is similar to T. autumnalis in having impunctate pronotum and moderately wide genae. These two North American species are somewhat isolated from the Asian and Australian species and may represent one or two separate species groups within Iridessus .

The name Harpalus fulgens Csiki, 1932 was introduced instead of H. nitidulus Chaudoir, 1843 because of the supposed secondary homonymy with H. nitidulus (Stephens, 1828) . However, Stephens’ name Ophonus nitidulus actually refers to Carabus nitidulus Schrank, 1781 [now in Chlaenius ] (see Telfer, 2001: 34; Wrase, 2005: 835) and is thence unavailable ( International Commission on Zoological Nomenclature, 1999: Article 49). Since Stephens’ name does not fall under the rules of homonymy ( International Commission on Zoological Nomenclature, 1999: Article 54.2), H. fulgens Csiki, 1932 is the unnecessary substitute name (junior objective synonym) for H. nitidulus Chaudoir, 1843 . Therefore, the valid name of the species being considered should be Trichotichnus nitidulus . This removes the problem (see Bousquet, 2012: 1158) of the junior primary homonymy of H. fulgens Csiki, 1932 with H. fulgens Dejean, 1829 .