Pterostichus (Circinatus) zhygealu, 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 : 25-29

Taxon classification Animalia Coleoptera Carabidae

Pterostichus (Circinatus) zhygealu sp. n. Figures 8, 38, 54, 75, 94, 117

Type locality.

Sichuan: Dafengding national reserve, Yizi pass between Meigu and Ebian County (N28.67477° E103.05248°), altitude 2923 m.

Type material.

Holotype (IZAS): male, body length = 13.5 mm, pin mounted, genitalia dissected and glued on plastic film pinned under specimen, "CHINA, Sichuan prov., Yizi / pass btw. Meigu county and / Ebian county, mixed forest, / 2923 m, / N28.67477 E103.05248 "; "2012.VI.12, in dead log, / SHI Hongliang, LIU Ye leg., / Institute of Zoology, CAS. / 美姑县-峨边县椅子垭口”; "HOLOTYPE ♂/ Pterostichus (Circinatus) / zhygealu new species / des. SHI H.L. 2015" [red label]. Paratypes, a total of 3 males and 7 females: 1 male, 2 females (IZAS): the same data as holotype. 2 males, 5 females (IZAS): "CHINA, Sichuan Prov., Yizi pass btw. Meigu county and Ebian county, mixed forest; N28.67477 E103.05248, 2923 m; 2012.VI.15; by pit fall trap; SHI Hongliang & LIU Ye leg.".

Non-type material.

1 female (IZAS): "CHINA, Sichuan, Mianning county, Yele conservation, mixed forest, N28.96508, E102.16137; 2988 m, 2012.VI.22, under stone, YANG Xiaodong lgt."

Diagnosis.

Relatively large-sized species within subgenus; pronotum with three or four mid-lateral setae; hind angle completely rounded; outer basal foveal groove faintly defined, approx half length of inner one, outer area of inner groove distinctly concave; elytron with distinct transverse or isodiametric microsculpture; humeral tooth indis tinct, not pointed; males with terminal sternum unmodified, penultimate sternum weakly tumid on each side; apical lamella of aedeagus long, slightly hooked to left.

This new species can be easily distinguished from all other species of the agilis -group by its distinct larger size. Including the new species, a total of three known Circinatus species (the other two are Pterostichus agilis and Pterostichus camelus sp. n.) have their male secondary sexual characters on the penultimate sternum. Pterostichus camelus sp. n. is distinguishable from the others by its fifth tarsomeres setose, and different male penultimate sternum. Pterostichus agilis is the species most similar to Pterostichus zhygealu sp. n. in their similar male secondary sexual characters on penultimate sternum (weakly tumid on each side). These two species can be separated by: (1) Pterostichus zhygealu sp. n. is much larger than Pterostichus agilis ; (2) Pterostichus zhygealu sp. n. have the outer groove of the pronotal basal foveal present, but completely vanished in Pterostichus agilis ; (3) elytral humeral tooth almost invisible in Pterostichus zhygealu sp. n., but sharp and distinct in Pterostichus agilis ; (4) apical lamella of aedeagus with obtuse hook in Pterostichus zhygealu sp. n., but simple in Pterostichus agilis .

Among its sympatric species, Pterostichus zhygealu sp. n. is most similar to Pterostichus adelphus sp. n. In addition to the difference in size, they also differ in elytral microsculpture: isodiametric or transverse in Pterostichus zhygealu sp. n., very faint and linear in Pterostichus adelphus sp. n.

Description.

Body form stout, body length 13.5-14.5 mm; dorsal side black, shining; elytron without iridescent shine; mouthparts, antenna and tarsus dark brown; ventral side blackish. Both sexes with distinct elytral microsculpture, isodiametric on disc, gradually turned to transverse on elytral apex and outer intervals. Head. Frons without punctures; antenna reaching elytron basal fifth; gena approx same length as eye, briefly tumid behind eye. Pronotum round, widest at approx anterior third, PW/PL = 1.22-1.28; usually four (sometimes three) mid-lateral setae present, first one close to anterior angle, last one near middle of lateral margin, a little distant from others; posterior seta distant from hind angle, distance between seta and hind angle approx same as distance between hind angle and inner basal foveal groove; hind angle completely rounded; basal fovea shallow, faintly defined; inner groove subparallel to median line, slightly curved outwards; outer groove faint, approx half length of inner one, outer area of inner groove distinctly concave; basal foveal area usually impunctate, sometimes with sparse punctures on inner side of inner groove. Elytron oviform, with basal ridge weakly oblique; elytral shoulder slightly narrowed, basal ridge and lateral margin forming obtuse angle, humeral tooth indistinct, not pointed; intervals feebly convex; striae moderately deep, without punctures; scutellar stria short, usually incomplete; third interval with two setigerous pores adjacent to second stria; umbilical pore series on ninth interval sparse in middle, composed of 15-18 pores (6, 1-3, 7-9). Ventral side. Proepisternum impunctate; mesepisternum finely punctate on anterior half; metepisternum impunctate or very sparsely punctate; penultimate sternum of males very faintly tumid on each side, tumidities close to primary setae, middle region between tumidities faintly depressed (Fig. 117); terminal sternum of males without special structure. Legs. Fifth tarsomeres without setae beneath; males with apical half of mesotibia slightly widened, inner margin slightly crenulate; first metatarsomere with distinct carina on outer surface, such carina on second metatarsomere superficial. Male genitalia. Median lobe of male genitalia bent approx 90 degrees, apex slightly bent ventrally (Fig. 38A); ventral margin straight in middle, slightly sinuate before apex; dorsal margin gradually curved; apical orifice large, slightly turned to left side, not opened on ventral side; apical lamella long, approx half length of apical orifice, laminate, not thickened; in dorsal view, apical lamella distinctly inclined to right, nearly triangular with rounded apex, apex a little enlarged, slightly hooked to left; apical lamella length approx 1.5 times basal width (Fig. 38B). Right paramere straight and fine, length approx 3.5 times greatest width, apex rounded (Fig. 38C). Endophallus (Fig. 38 D, E, F) bent to ventral side across apical lamella; gonopore (gp, gonopore lobe folded in Fig. 38) located at level of apical lamella, pointing to aedeagal base. Four distinct lobes recognized, the three (vb-I, vb-II, va) located on ventral side of endophallus strongly chitinized: ventral-basal lobe I (vb-I) close to base of apical lamella, very small, covered by vb-II, upper surface strongly chitinized, lower surface membranous; ventral-basal lobe II (vb-II) larger than vb-I, upper surface strongly chitinized, lower surface membranous, apex of lower surface distinctly projected; ventral-apical lobe (va) close to apex of apical lamella, approx same length as vb-II, upper surface strongly chitinized, its apex strongly prolonged and sinuate, lower surface membranous; right lobe (rl) small and rounded, decorated with fine scales. Female genitalia. Spermatheca (Fig. 54) with seminal canal approx 5.5 times as long as receptaculum; receptaculum capitate, club approx half length of receptaculum; spermathecal gland slightly expanded; seminal canal inserted at base of common oviduct, base of seminal canal sclerotized. Stylomere II with two ensiform setae at outer margin, and one near middle of inner margin; two short nematiform setae located in a furrow near apex. Female sternum VIII (Fig. 75B) with dense and fine spines on posterior margin; posterior margin rounded, shallowly notched in middle; posterior region well chitinized, anterior region also, middle transparent region V-shaped, almost adjacent to posterior notch in middle. Female tergum VIII (Fig. 75A) with anterior half chitinized, posterior half semi-chitinized pigmented with sparse spots, without transparent region in middle.

Distribution.

Most specimens of this species were collected from the type locality (Yizi pass) on the border between Meigu and Ebian County (Sichuan, Liangshan Yi Autonomous Prefecture). One female, slightly different from other specimens, was collected in Yele Reserve in Mianning County. (Map 2)

Etymology.

The scientific name of the new species comes from Zhygealu , an honored hero in the Yi people’s legend. Yi is the local nation living in Liangshan Yi Autonomous Prefecture (Sichuan Province), where all known species of the agilis -group are distributed. This species deserves a hero’s name as the largest-sized of all known agilis -group species.

Affinities.

This new species is closest to Pterostichus agilis . Despite the difference in size, these two species are very similar in the following characters: (1) elytral microsculpture transverse or isodiametric; (2) male secondary sexual characters on the penultimate sternum; and (3) apical lamella of the aedeagus long and bent to the right. The type locality of Pterostichus agilis is Luojishan (Sichuan), a mountain approximately 150 km southwest of the Yizi Pass, which is the type locality of Pterostichus zhygealu sp. n.

Habitat.

Pterostichus zhygealu sp. n. was collected in mixed forest with dominant large pines, and rich in dead logs. In daytime, they hide in dead logs, usually under bark. In nighttime, they come out, and can be trapped by pitfalls. Pterostichus zhygealu sp. n. lives together with three other Circinatus species. Among them, Pterostichus zhygealu sp. n. and Pterostichus adelphus sp. n. are rarer than the other two species ( Pterostichus bullatus and Pterostichus cavazzutianus ).

Variation.

One female collected from Mianning County is slightly different from the holotype and the paratypes in the following characters: pronotum narrower, strongly narrowed to base, and body size small with a body length of 12.7 mm. Because of these morphological differences and a different locality (approximately 100 km NW of the type locality), we suspected that it might represent a different subspecies and excluded it from the type series.