Trigonotoma digitata, Zhu & Shi & Liang, 2020

Zhu, Pingzhou, Shi, Hongliang & Liang, Hongbin, 2020, Notes on the genus Trigonotoma from China, with descriptions of two new species (Carabidae, Pterostichinae), ZooKeys 921, pp. 49-64 : 49

Trigonotoma digitata sp. nov. Figures 1-4

Type locality.

Guangdong: Xinfeng, Yunji Mountain (24.12N, 114.16E), altitude 1318 m.

Type material.

Holotype: Male (IZAS), BL = 17.2 mm, board mounted, genitalia preserved in 100% ethanol in a microvial pinned under specimen, "China, Guangdong, Xinfeng, Yunji Mountain, pitfall trap, 24.115841N, 114.163535E "; "1318 m, 2017.V.20-25, Liu Y. Z. & Yu S. P. lgt., Institute of Zoology, CAS, Yunji Mountain, Xinfeng"; "HOLOTYPE ♂ Trigonotoma digitata sp. nov., des. ZHU & SHI 2019" [red label].

Diagnosis.

Dorsal side bicolored, with strong metallic luster, pronotum cupreous green, elytra dark purple; pronotum slightly narrowed to the base; posterior angles completely rounded; pronotal base including the basal fovea completely glabrous; basal fovea with inner and outer grooves well defined; metepisternum short and wide, length subequal to its basal width; median lobe of aedeagus strongly lobed and notched on the left margin.

Comparison.

The new species is different from all other known species of Trigonotoma by its distinct male genitalia (Fig. 3 ). At first glance, the new species is very similar to T. lewisii in external appearance, but these two species can be readily distinguished by the differences of metepisternum and male genitalia.

Description.

BL = 17.2 mm, BW = 6.2 mm. Dorsal side bicolored with strong metallic luster: head and pronotum cupreous green, elytra purple; appendages dark, antennomeres 2-11, labial and maxillary palpi, apex of mouthparts and tarsomeres dark brown; ventral side black, without metallic luster. Head and pronotum with isodiametric microsculpture and minute punctures; elytra with transversal microsculpture.

Head with vertex smooth; frontal impressions deep and straight, longitudinally extending to the level of midpoint of eyes; labrum and clypeus both with anterior margins deeply emarginate; temporae straight, not swollen behind eyes; antennae reaching pronotum basal quarter.

Pronotum slightly transverse, PW/PL = 1.24, widest near anterior third; lateral margins curved in middle, and then gently narrowed to base, PW/PBW = 1.55; lateral margins straight in front of posterior angles, posterior angles rounded, not forming distinct angle; anterior margin straight, anterior angles widely rounded; posterior margin of nearly same width as anterior margin, gradually extended backward at lateral sides; disc completely glabrous, gently convex; median line fine but clearly defined, almost reaching posterior margin. Basal fovea deep and glabrous, without puncture or wrinkle; inner and outer grooves well defined, region between them deeply depressed, inner groove straight, slightly longer than curved outer groove.

Elytra oviform, EL/EW = 1.63, widest near posterior third; basal ridge complete, curved at fourth interval; humeral angles rounded, without teeth; intervals fairly convex, striae deeply incised, with coarse punctures; parascutellar striae short, apex almost conjunct to first stria; parascutellar pore present; third interval without setigerous pore; umbilicular series on ninth interval composed of approximately 25 pores, sparse in middle.

Ventral side: Propleuron and mesoepisternum with sparse and coarse punctures; metepisternum short and wide, ML/MW = 1.02, with sparse and coarse punctures; abdominal sternites glabrous on middle, with a few coarse punctures on lateral sides of sternites II and III, and shallow wrinkles on lateral sides of all sternites.

Legs: Metatarsomeres I and II strongly carinate on basal 3/4 of outer surface, distinctly carinate on basal half of mesotarsomere I and metatarsomere III; fifth tarsomeres of all legs with three or four pairs of spines ventrally.

Median lobe of male genitalia bent approx. 45° (the included angle between apical lamella and axes of basal portion of aedeagus). Apical orifice long and sinuate, constricted in middle, opened dorsally, and slightly turned to left. In dorsal view, right margin of aedeagus straight, and then sinuate before apical lamella; left margin with a digitiform lobe near midpoint of apical orifice, deeply notched anterior to lobe, and then widely arched reaching apex of apical lamella; apex of digitiform lobe rounded and bent to dorsal side; apical lamella short and wide, length approx. half its basal width; strongly bent to right, apex truncated, without tooth; dorsal surface without ridge.

Endophallus (Fig. 4 ) rotated to dorsal-left direction of aedeagus, major portion of endophallus on dorsal side of aedeagus; gpl folded so, invisible in Fig. 4 ; bb elongated, extended from apical orifice to middle part of endophallus; cp at left margin of apical orifice. Three distinct lobes recognized: bl moderately large, slightly prolonged, located at base of apical orifice, pointing to apical direction of aedeagus, membranous, without scales; lb small, rounded, located at base of endophallus and left side of apical orifice, pointing to left basal direction of aedeagus; la smaller than lb, rounded, located at left side of endophallus, with fine scales. Apex of endophallus large, elongate, with heavy spines on central and basal surfaces, and fine scales on other areas.

Distribution.

Yunji Mountain, Xinfeng, Guangdong. Only known from the holotype.

Etymology.

The specific epithet digitata is based on the Latin for finger and indicates the finger-shaped lobe on the aedeagus of the males. It is treated as an adjective in the nominative singular.

Figures

Figures 1 - 4. Trigonotoma digitata sp. nov. 1 Habitus of holotype (male, Guangdong, IZAS) 2 labels of holotype 3 median lobe of aedeagus (holotype) A dorsal view B left lateral view 4 endophallus (holotype) A left lateral view B dorsal view C right lateral view D apical view.