Pterostichus (Circinatus) dimorphus, Shi, Hongliang & Liang, Hongbin, 2015

Shi, Hongliang & Liang, Hongbin, 2015, The genus Pterostichus in China II: the subgenus Circinatus Sciaky, a species revision and phylogeny (Carabidae, Pterostichini), ZooKeys 536, pp. 1-92 : 11-14

Taxon classification Animalia Coleoptera Carabidae

Pterostichus (Circinatus) dimorphus sp. n. Figures 17, 18, 44, 65, 81, 103, 123, 133

Type locality.

Yunnan: Dayao County, Xiaobaicaoling, Zhuanwanhe station (N26.07700°, E101.03183°), altitude 2881 m.

Type material.

Holotype (IZAS): male, body length = 11.8 mm, pin mounted, genitalia dissected and glued on plastic film pinned under specimen, "CHINA, Yunnan, Dayao, / Santai town, Xiaobaicaoling / Mt., Zhuanwanhe con. stat. / N26.07700, E101.03183 "; "2881 m, 2012.V.29 night, / mixed forest, / SHI Hongliang, LIU Ye leg. / Institute of Zoology, CAS / 三台乡小白草岭转弯河”; "HOLOTYPE ♂/ Pterostichus (Circinatus) / dimorphus new species / des. SHI H.L. 2015" [red label]. Paratypes, a total of 3 males and 2 females: 1 female (IZAS): the same data as holotype. 1 male, 1 female (IZAS): "CHINA, Yunnan, Dayao, Santai town, pass of Xiaobaicaol ing, 3105 m, N26.05615, E101.05448, 2012.V.30 day, in dead wood, mixed forest, SHI Hongliang leg.". 1 male (IZAS): "CHINA, Yunnan, Dayao, Santai town, pass of Xiaobaicaoling, 3105 m, N26.05615, E101.05448, 2012.V.29 day, under stone, mixed forest, SHI Hongliang leg.". 1 female (IZAS): "CHINA, Yunnan, Dayao, Santai town, pass of Xiaobaicaoling, 3105 m, N26.05615, E101.05448, 2012.V.30, pit fall trap, mixed forest, SHI Hongliang & LIU Ye leg."

Diagnosis.

Pronotum with single mid-lateral seta; hind angle completely rounded; basal fovea almost impunctate; each sex with different elytral microsculpture: granular in females (elytron luster dull), and isodiametric as usual in males; terminal sternum of male weakly depressed in middle, with two sharp teeth near posterior margin pointing to apex of sternum.

The females of this new species can be rapidly distinguished from all the other Circinatus species by the special granular elytral microsculpture. The males are similar to Pterostichus liciniformis . In addition to the different sexual characters on the male terminal sternum, Pterostichus liciniformis also differs from the new species by its smaller and stouter body form.

Description.

Body form fairly slender, body length 11.5-11.9 mm; dorsal side almost black, moderately shining, female elytron dull; elytron without iridescent shine; mouthparts, antenna, tarsus, and apex of tibia dark brown; ventral side blackish. Microsculpture isodiametric on vertex, transverse on pronotum. Elytral microsculpture different in each sexes: isodiametric as usual in males; granular in females, making elytral luster much duller in females. Head. Frons without punctures; antenna hardly reaching elytron base; gena approx same length as eye, briefly tumid behind eye. Pronotum narrowed to base, posterior margin a little narrower than anterior margin; lateral margin evenly rounded, widest a little before middle, PW/PL = 1.16-1.21; one mid-lateral seta present, located a little before greatest width; posterior seta far distant from hind angle, distance between seta and hind angle greater than distance between hind angle and inner basal foveal groove; hind angle completely rounded; basal fovea shallow, faintly defined; inner groove subparallel to median line, basal half oblique outwards; outer groove completely vanished, outer area of inner groove flat; basal foveal area with sparse and fine punctures on inner side of inner groove. Elytron oviform, with basal ridge slightly curved; elytral shoulder slightly narrowed, basal ridge and lateral margin forming obtuse angle, humeral tooth small but distinct; intervals almost even; striae moderately deep, with faint punctures inside; scutellar stria short, apex free; third interval with two setigerous pores adjacent to second stria; umbilical pore series on ninth interval sparse in middle, composed of 14-16 pores (5-6, 1-2, 7-9). Ventral side. Proepisternum impunctate, mesepisternum and metepisternum finely punctate; male terminal sternum weakly depressed in middle, with two sharp teeth close to posterior margin pointing to apex of sternum (Fig. 123). Legs. Fifth tarsomeres glabrous beneath; males with apical half of mesotibia slightly widened, inner margin not crenulate; only first metatarsomere with carina on outer surface, fairly distinct. Male genitalia. Median lobe of male genitalia bent approx 90 degrees, apex nearly straight, a little bent ventrally (Fig. 44A); ventral margin straight in middle, dorsal margin gradually curved; apical orifice large, slightly turned to left side, largely opened on ventral side (Fig. 133); in lateral view, apical lamella laminate, slightly twisted, apex not thickened, its length approx one fifth length of apical orifice; in dorsal view, apical lamella narrow and small, located on right side, pointing apically, length approx 1.5 times basal width, apex rounded (Fig. 44B). Right paramere straight and stout, inner margin slightly expanded near middle, length approx 3.5 times greatest width, apex rounded (Fig. 44C). Endophallus (Figs 44D, E, F) very thick, bent to ventral side from ventral opening of apical orifice, major portion of endophallus located on left-ventral side of aedeagus; gonopore (gp, gonopore lobe folded in Fig. 44) located close to aedeagal base, pointing to right side. Four distinct lobes recognized: left lobe (lf) large, apex bifid in left view, decorated with fine scales, located on left side of endophallus; right lobe (rl) large, pointed to right side with truncate apex in ventral view, located on ventral side of endophallus, adjacent to vl, with a small pigmented patch near base; ventral lobe (vl) smaller than rl, composed of two sub-lobes, with a narrow pigmented band across its full width; pre-apical lobe (pa) indistinct, weakly pointed, just before gp; basal lobe absent. Ventral piece (vp, only partly shown in Fig. 44F) is a short and arcuate chitinized piece, located just behind gp. Female genitalia. Spermatheca with seminal canal approx two times as long as receptaculum; receptaculum clavate (Fig. 65); seminal canal inserted at base of common oviduct, base of seminal canal with a very fine sclerotized spine. Stylomere II with two ensiform setae at outer margin and one at middle of inner margin; two short nematiform setae located in a furrow near apex. Female sternum VIII (Fig. 81B) with dense and fine setae on posterior margin; posterior margin curved, deeply notched in middle; posterior region chitinized, anterior region semi-chitinized, pigmented with sparse denser areas; anterior margin notched in middle; middle transparent region arrow-shaped, adjacent to posterior and anterior notches in middle. Female tergum VIII (Fig. 81A) with most of region semi-chitinized, pigmented with dense spots, only lateral-anterior region with two chitinized patches.

Distribution.

This species is known only from Xiaobaicaoling Mts., Dayao County of north Yunnan (Map 1). The two collecting localities are very close, approx 1 km apart. The altitude range is 2881-3105 m.

Etymology.

The scientific name “dimorphus” of the new species comes from Greek meaning "two forms", referring to the different elytral luster between male and female.

Affinities.

This new species appears close to Pterostichus liciniformis and has the following similarities: the pronotal hind angle completely rounded, males with the terminal sternum distinctly concave, and the median lobe of the aedeagus with the apical orifice opened ventrally. These two species are the only members of the baenningeri -group that have the typical Circinatus pronotum (posterior seta distant from hind angle; hind angle completely rounded). However, based on aedeagal characters (apical orifice largely opened on the ventral side and apical lamella abruptly narrowed after the apical orifice), Pterostichus dimorphus sp. n. could also be close to Pterostichus wangjiani .

Habitat.

Pterostichus dimorphus sp. n. was collected in mixed forest with dominant large pines and rhododendron trees approx 3 - 5 m tall. Some individuals were found inside dead logs in day time, others were found running along tree trunks during night or were taken by pitfall traps.