Protrechiama, Belousov & Kabak, 2003

Belousov, Igor A., Kabak, Ilya I. & Liang, Hongbin, 2019, New species of the tribe Trechini from China (Coleoptera: Carabidae), Zootaxa 4656 (1), pp. 143-152 : 150-152

Protrechiama сrassipes ( Uéno, 1997)

( Fig. 6 )

Trechiama crassipes Uéno, 1997: 38 . Type locality: “Mt Dafengding, Wahei Xiang of Meigu Xian, southern Sichuan ”. Protrechiama crassipes: Uéno, 2006 .

Material examined: CHINA: 1♀, with label data “ China, Sichuan prov., Yizi Pass btw. Meigu County and Ebian County , mixed forest, 2923 m, N 28.67477, E 103.05248 ”; “ 2012.VI.12, in dead log, Shi Hongliang, Liu Ye leg., Institute of Zoology , CAS. [In Chinese]: Meigu Xian—Ebian Xian, Yizi Yakou” ( IOZ) .

Although the species was adequately and thoroughly described by S.–I. Uéno (1997), we give here its description based on newly available female specimen from another collecting site in order to illustrate variation in some characters and to draw attention to some others. In addition, the photograph will help in more accurate understanding of external morphology, in particular concerning the shape of pronotum.

Description. The smallest species of the genus, body length 4.8 mm. Habitus relatively narrow, subparallel, depressed, with rather thick (compared to congeners) antennae and legs ( Fig. 6 ).

Color of dorsum amber brownish, with slightly darker posterior portion of head and disc of pronotum and elytra. Appendages pale reddish.

Microsculpture fine, consisting of well-engraved rather small isodiametric meshes on head, very shallow irregular transverse meshes on pronotum and fine transverse lines on elytra. All upper surface finely micropunctured and faintly iridescent.

Head somewhat trapezoid ( PW / HW 1.34), eyes medium-sized (YL/TL 1.42, L3/YL 1.12), slightly convex; tempora glabrous, slightly convex anteriorly, much more markedly in posterior portion. Frontal furrows rather deep, subparallel in median portion, more deeply impressed and divergent anteriorly, abruptly divergent posteriorly. Parietal transverse impression distinct. Supraorbital setiferous pores located in lines clearly convergent posteriad, anterior one deeply, posterior one moderately foveolate. Anterior margin of labrum concave. Mandibles relatively slender, evenly curved. Tooth on right mandible not large, with long basis, tridentate, median denticle being shortest, while the distal one—longest. Labial tooth distinctly cleft at apex. Labial suture very fine but traceable. Six submental setae. Segments of maxillary palpi of medium length, fusiform, glabrous. Penultimate segment of the labial palpi quadrisetose. Ligula obtusangular, blunt at apex, with two long apical setae and three lateral setae on each side. Paraglossae moderately long, slender, arcuate and distinctly pubescent.Antennae average in length, rather thick, AL/EL 1.04, middle antennomeres approximately twice as long as wide, L3/ W3 2.60, L3/L2 1.46.

Pronotum transverse ( PW / PL 1.27), markedly contracted to base ( PW / PB 1.39), slightly wider at base than at apex ( PB /PA 1.14). Lateral margins convex nearly for all of their length, except for a slight and shallow emargination just before hind angles, markedly reflexed, especially in their posterior portion. Hind angles rather small and slightly obtuse, with blunt apices. Anterior margin concave, front angles rounded, slightly but distinctly produced anteriad. Posterior margin straight medially, obliquely emarginate laterally. Disc of pronotum slightly convex, depressed along suture, basal foveae large and deep. Prebasal transverse impression not sharply impressed. Base of pronotum irregularly wrinkled. Apical transverse impression distinct, triangular-shaped. Median line distinct but rather shallow. Lateral groove rather wide, its inner margin slightly waved. Discal foveae shallow. Anterior lateral seta located in anterior third of pronotum (PSa 34%), posterior one just at hind angles.

Elytra ( EL / PL 2.70; EW/ PW 1.39; EW /HW 1.86) rather narrow ( EL / EW 1.53), subparallel, depressed on disk ( EL /BH 2.44), their sides only marginally convex in their median portion; maximum width slightly behind middle, apex truncate. Humeri distinct though rounded. Marginal groove narrow. Elytral striation distinct: inner striae deep and coarsely punctured, outer striae shallower but traceable, finely punctured. Striolation on the apical slope distinctly engraved. Stria 8 shallow in anterior portion, becoming deeper on the apical slope and angularly curved near umbilicate pore 7, interval between stria 8 and the apical striole wide and convex, narrowing to the elytral apex, the neighbouring outer interval, on the contrary, plane. Inner interspaces subconvex, outer interspaces flat. Parascutellar striole long and deep, scutellar pore present. Apical striole nearly straight in anterior portion, abruptly terminated anteriorly at level slightly behind umbilicate pores 7; apical carinula well-developed and sharply delimited. On each elytron, 10 foveolate setiferous pores arranged in two irregular longitudinal series. The inner series, apart from the preapical pore, consists of four setae, of which the anterior one located in stria 2 and the remaining three pores in stria 3. The outer series consists of five pores located in stria 5. Preapical pore situated in the apical cross of striae 2 and 3 markedly behind the anterior termination of the apical striole, DP 91.9%. All pores of the apical triangle present, the inner side of the apical triangle is divergent from the elytral suture posteriad, since the angulo-apical pore shifted outward and located much closer to the exterior pore than to the elytral suture. All umbilicate pores well-aggregated within their groups, equidistant, except for pores 7 and 8 which are markedly more spaced. Umbilicate formula U1–8: 7.9%, 13.8%, 19.8%, 25.2%, 64.2%, 69.6%, 84.9%, 92.8%.

Ventral surface: metepisternites clearly longer than wide. Abdominal sternite 2 without setae, sternite 3 with one pair of paramedian setae, sternites 4 and 5 with 2–3 (usually 2) pair of setae. Anal sternite quadrisetose in one female specimen studied.

Legs rather thick, foretibiae sharply grooved and carinate on exterior surface, nearly glabrous, with only a few hairs just near the tibia apex on their anterior surface. Hind tibia ratios: EL/HTi 1.93; HTi/HTa 1.31.

Comparative notes. As it was indicated by Uéno (1997), P. crassipes is the most isolated species of the genus, although it shares all major characters of other congeners: the number and disposition of elytral setiferous pores (closer to the lower limit of variation in P. glabricollis Belousov & Kabak, 2003 and P. marginalis Belousov & Kabak, 2003 ), the anterior discal setiferous pore located in stria 2, the absence of setae on the pronotal disc and the broad lateral groove of the pronotum. However, P. crassipes differs readily from all other currently known Protrechiama in much smaller size (4.8-5.25 mm from anterior margin of labrum for all specimens currently known vs. more than 6.65 mm in other species), short and flat elytra (vs. long and convex, oblong-ovate elytra) and, specifically, much stouter legs and antennae with middle antennomeres only marginally more than twice as long as wide (vs. more than 3 times as long as wide in other species).

The female from the Yizi Pass differs from the type series in the following characters: 5 setiferous pores attached to stria 5 vs. 3–4 in the type specimens; shape of pronotum with basal margin straight medially vs. salient, nearly arcuate in the types specimens and tempora more evenly convex in anterior portion vs. nearly straight in the type specimens. These differences do not seem to be of great taxonomic importance and, for the moment, we prefer to consider the female from the Yizi Pass to be conspecific with the type series. Additionally, it is worth noting that figure 1 in the original description is slightly misleading with regard to, at least, basal foveae of pronotum which are large according to the paper text and nearly missing in the figure ( Uéno 1997).

Distribution. All of the known members of the genus Protrechiama are confined to a rather small mountainous area between the Niuri River in the west, the Dadu River in the north and the Yangtze River in the east. P. crassipes is not an exception, two known collecting sites are located less than 10 km from each other in the north of Meigu County and in the Yizi Pass between Meigu and Ebian counties.

Bionomics. The species was found in a mixed forest at rather low elevations from 2300 to slightly exceeding 2900 m a.s.l.

Figures

FIGURE 6. Protrechiama crassipes (Uéno, 1997) female, habitus.