Notes on the genus Xestopus from China, with description of a new species (Carabidae,Sphodrini, Dolichina)

Abstract The genus Xestopus Andrewes, 1937 in China is reviewed, with the description of a new species: X. gutangensis Zhu & Kavanaugh, sp. nov. (type locality: Xizang: Mêdog, 29.46414°N, 95.73563°E). The male of X. cyaneus Sciaky & Facchini, 1997 is described for the first time, and the first record of this species in Yunnan, China, represents an eastward range extension for the species. A key is provided for the eight known species of the genus.


Introduction
Xestopus Andrewes, 1937 (Sphodrini, Dolichina) is a small genus previously comprised of seven species, all distributed along the Himalaya (Nepal, Bhutan, China, and Myanmar). This genus is differentiated from related genera mainly by its larger size (15 mm > BL > 25 mm) and the hooked right paramere of the male genitalia (Sciaky and Wrase 1998).
Type species. Pristonychus alticola Fairmaire, 1889 (type locality: Mountain Yeomatong, North Myanmar; holotype in NZSI), by monotypy. Diagnosis. Among the seven genera of Dolichina, Xestopus can be distinguished from others by the following character combination: third antennomere very long, usually longer than the first two antennomeres combined; tooth of mentum bifid; pronotum more or less cordiform; elytra with microsculpture nearly isodiametric, parascutellar seta present, elytral disc without setigerous pores; lateral grooves absent on metatarsomeres I-IV; males with right paramere hooked at apex; female apical gonocoxite with one ensiform seta at external margin (in most specimens) and sensory pit absent. Detailed descriptions and a key to the genera in the subtribe Dolichina have been provided by Casale (1981) and Sciaky and Wrase (1998).
Comparisons. This genus is most similar to the genus Dolichus Bonelli, sharing the large body size (>15 mm), but its members differ from those of the latter in having the tooth of the mentum bifid, the pronotum cordiform, elytral interval 3 without setigerous pores, and the right paramere of male genitalia apically hooked.
Distribution. This genus includes eight species distributed along the Himalayas (two in Nepal, three in Bhutan, two in China, and one in Myanmar).
Remarks. The type species of this genus, Xestopus alticola (Fairmaire, 1889) was described from Mount Yeomatong, northern Myanmar. In the two versions of the Catalogue of Palearctic Coleoptera (Hovorka and Sciaky 2003;Hovorka 2017), the distribution of this species includes Sichuan and Sikkim and both these two are doubtful. The record for Sikkim was added by Andrewes (1937); however, this locality and the type locality are extremely distant from each other for a species with apterous members. In addition, the record for Sikkim maybe a different species (Morvan 1979;Casale 1981). No other literature records have reported X. alticola from Sichuan, and, in fact, no Xestopus specimens have been found in that province during our many expeditions in Sichuan, so we also doubt the reliability of this distributional record. Casale (1981) pointed out that the three species from Bhutan (X. walteri (Morvan, 1978), X. bhutanensis (Morvan, 1979), and X. cordicollis (Morvan, 1979)) may represent three subspecies of a single species or eventually be combined into one species when abundant materials are available. Conversely, the male allotype and female holotype of X. nepalensis probably represent two different species, in our opinion, based on the original description and figures. The male differs from the female in having elytra with (1) rufous color in the scutellar region and along the sutural margin to mid-length, (2) the humeri more rounded, (3) the basal margination markedly sinuate, and (4) the apices more rounded and slightly oblique medially. Thus, a revision appears necessary to deal with this situation.  Diagnosis. Dorsum black, elytra with more or less bluish metallic luster. Anterior supraorbital setae present. Pronotum with lateral margins faintly sinuate before posterior angles. Apices of elytra rounded (Fig. 6). Hind wings full-sized. Metepisternum long and narrow.

Xestopus gutangensis
Comparisons. This new species is most similar to Xestopus cyaneus, sharing the bluish elytra and full-sized hind wings, which are distinctive features in the genus. X. gutangensis sp. nov. can be readily distinguished from X. cyaneus by: (1) anterior pair of supraorbital setae present; (2) apices of elytra rounded; (3) apical lamella of median lobe strongly bent ventrally like a hook; (4) endophallus without a densely setose area on left side; (5) gonocoxite II of female ovipositor very long. Supernumerary setae have been found in some X. gutangensis specimens in the area of the posterior supraorbital setae, on the pronotal lateral margins and posterior angles, and on the external margin of gonocoxite II (as ensiform setae). These additional setae were not observed on any of the specimens of X. cyaneus that we examined. Description. BL = 15.7-18.0 mm, BW = 6.4-7.8 mm. Dorsum ( Fig. 1) black, elytra with more or less bluish metallic luster, very faint in some specimens; appendages dark, antennomeres 4-11, labial and maxillary palpi, apex of mouthparts and tarsomeres dark brown; venter black, without metallic luster. Head, pronotum and elytra with strong isodiametric microsculpture.
Head with vertex smooth; frontal impressions shallow and curved, in front of eyes; clypeus with anterior margin faintly emarginate; labrum with anterior margin straight; temporae slightly swollen behind eyes; both anterior and posterior pairs of supraorbital setae present (two pairs of posterior supraorbital setae present in a few specimens); antennae long and slender, extended to basal one-third of elytra.
Pronotum cordiform, slightly transverse, PW/PL = 1.38-1.55, widest near anterior quarter; anterior margin markedly concave, slightly wider than basal margin, PAW/ PBW = 1.13-1.33, lateral margins broadly rounded before middle, then distinctly narrowed to base, faintly sinuate before posterior angles, PW/PBW = 1.31-1.50, lateral margins with one pair of setae at widest points and posterior angles respectively (with an additional seta on one or both sides and at either or both widest points and posterior angles), basal margin straight; anterior angles rounded, moderately extended forward, posterior angles distinctly obtuse; disc glabrous, gently convex; median line fine but clearly defined; basal fovea large and deep, without punctures but with some wrinkles; lateral explanations very wide and impunctate.
Legs long and slender, all tarsi smooth, claws distinctly denticulate in basal half. Male genitalia. Median lobe (Figs 3, 7) long, slender, and straight but slightly bent ventrally; apical orifice opened dorsally, very long and wide, from basal bulb to apical lamella; in dorsal view (Fig. 3A), left and right margins both straight, apical lamella long, length about twice its basal width, apex rounded; in left lateral view (Fig. 3B), ventral margin weakly expanded in the middle, apical portion slightly bent dorsally and then strongly bent ventrally like a hook at apex. Left paramere (Fig. 5) large and round, with a membranous filament at apex. Right paramere (Fig. 4) markedly styloid and curved, the angle between basal portion and apical portion near 90°; apical portion moderately bent ventrally, apical hook rounded. Endophallus (Fig. 7) simple, with only a single large lobe, straight, extended right at an angle of about 30° relative to longitudinal axis of the median lobe in dorsal view (Fig. 7D); surface smooth, without setae or scales; gonopore and gonopore lobe folded in this specimen.  (Figs 8-10). Gonocoxite II of ovipositor very long, length about four times basal width, with one ensiform seta at external margin in most specimens (two ensiform setae in a few specimens and ensiform seta very small in some specimens), sensory pit of apical gonocoxite absent. Bursa copulatrix very large, rounded. Spermatheca moderately long and tube-like, length about five times maximum width. Distribution (Fig. 19). This species is known from Bomi and Mêdog counties, Xizang, and from the northern part of the Dulongjiang valley in Gongshan County, Yunnan.

Female genitalia
Etymology. The new species is named for Gutang Township, where the type locality, Mêdog, is located.
Affinities. Among all Xestopus species, only X. gutangensis and X. cyaneus have the bluish elytra and full-sized hind wings. Thus, a close relationship of these two species is likely, and the absence of anterior supraorbital setae in the latter is clearly apomorphic within the genus.  (Fig. 2) black, elytra with more or less bluish metallic luster. Anterior pair of supraorbital setae absent (an anterior supraorbital seta present on one or both sides in a very few specimens). Pronotum with lateral margins very faintly sinuate before posterior angles. Apices of elytra acute (Fig. 12). Hind wings full-sized. Metepisternum long and narrow.
Male genitalia. Median lobe (Figs 11, 15) long, stout and straight but slightly bent ventrally; apical orifice broadly open dorsally, very long and wide, from basal bulb to apical lamella; in dorsal view (Fig. 11A), left and right margins both straight, apical lamella very long, length about three times as its basal width, moderately dilated in the middle, apex acute; in left lateral view (Fig. 11B), ventral margin straight, not expanded in the middle, apical portion slightly bent ventrally, apical lamella thick and straight. Left paramere (Fig. 13) large and round, with a membranous filament at apex. Right paramere (Fig. 12) strongly styloid and curved, the angle between basal portion and apical portion nearly 100°; apical portion straight, apical hook acute. Endophallus (Fig. 15) simple, only a single large lobe, straight, extended left at an angle of about 45° relative to longitudinal axis of the median lobe in dorsal view (Fig. 15D); surface with a densely setose area present on left side, without scales; gonopore lobe long and narrow, located at apex of endophallus, gonopore directed toward apex.
Female genitalia . Gonocoxite II of ovipositor moderately long, length about three times basal width, with one ensiform seta at external margin, sen-sory pit of apical gonocoxite absent. Bursa copulatrix large and elongate. Spermatheca moderately long and tube-like, length about five times maximum width. Distribution (Fig. 19). This species is known from Xizang (Bomi and Mêdog counties) and Yunnan (Gongshan and Fugong, new provincial record). The records from Sichuan cited by Hovorka and Sciaky (2003) and Hovorka (2017) is clearly wrong.
Remarks. The number of pairs of supraorbital setae is a very important character within Carabidae for both classification and systematics. In most members of the tribe Harpalini, only one pair of supraorbital setae is present at a middle position in relation to the diameter of the eyes, while most other ground beetles have two pairs of supraorbital setae. A few non-harpaline carabids lack one pair of supraorbital setae, but the other pair is present either in an anterior or a posterior position relative to the eyes instead of at the middle position as in Harpalinae. It is, therefore, usually easy to determine whether it is the anterior or posterior pair of supraorbital setae that is missing. Variation in this apparently apomorphic feature does not appear to have much value in high-level phylogeny. For example, members of genus Reflexisphodrus Casale, 1988 andgenus Eosphodrus Casale, 1988 (Sphodrini, Sphodrina) lack the posterior pair of supraorbital setae while those of Pterostichus subgenus Unitrichus Sciaky, 1997 (Pterostichini) lack the anterior pair just like most members of Xestopus cyaneus. The single species of Unitrichus, Pterostichus platyops Sciaky, 1997, from Yunnan, China, is distinguished from members of other subgenera of Pterostichus by the absence of the anterior pair of supraorbital setae and the presence of many setae at the middle of mentum. We have found a second, undescribed species from Yunnan, China with the similar appearance of P. platyops and many setae present at the middle of mentum, but with the anterior pair of supraorbital setae present (unpublished data), as in Xestopus gutangensis Zhu & Kavanaugh, sp. nov. These two examples show that differences in the number of supraorbital setae between closely related species is possible, even if it is rarely seen.
In our examination of 260 specimens of X. cyaneus and X. gutangensis Zhu & Kavanaugh, sp. nov., we found only five that had abnormal numbers of supraorbital setae for their species assignment based on other characters. All were clearly X. cyaneus based on the shape of the elytral apex and features of either male or female genitalia. Three of these, including one male from Xizang and one male and one female from Yunnan, had an anterior supraorbital seta present on one side but absent from the other. In addition, we found one female from Xizang and one female from Yunnan that had anterior supraorbital setae present on both sides. Consequently, the presence or absence of anterior supraorbital setae is slightly less reliable for distinguishing these two species than are the shapes of the elytral apices and male and female genitalia. Apices of elytra markedly truncate; pronotum longer, anterior angles more extended anteriorly, posterior angles more rounded; apical hook of right paramere more developed; apical lamella of median lobe narrower; 20-23 mm ...  (Morvan, 1979)