Trigonotoma constricta, 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 constricta sp. nov. Figures 5-8

Type locality.

Hunan: Guidong, Bamian Shan Mt. (25.99N, 113.71E), altitude 1510 m.

Type material.

Holotype: Male (IZAS), BL = 15.8 mm, board mounted, genitalia preserved in glycerin in a microvial pinned under specimen, "China, Hunan Guidong Co. Bamian Shan Mt., 25°59'33"N, 113°42'25"E, mixed forest, shrub, flower sifted & beating, ca. 1510m, 01.VI.2014, Peng, Shen, Yu & Yan"; “LX-5-1-1-8466”; "HOLOTYPE ♂ Trigonotoma constricta sp. nov., des. ZHU & SHI 2019" [red label].

Diagnosis.

Dorsal side bicolored, pronotum metallic dark green, elytra dark purple; pronotum strongly narrowed to the base; posterior angles obtuse-rounded; pronotal base including the basal fovea completely glabrous; basal fovea with inner and outer grooves vaguely defined, anterior half separated from each one, posterior half fused together; metepisternum short and wide, length subequal to its basal width.

Comparisons.

This new species can be readily distinguished from all other Trigonotoma from China by the narrowly constricted pronotum base. Trigonotoma concinna from Java has the pronotum shape and basal fovea very similar to T. constricta , but differs by its larger size (19-21 mm), longer metepisternum, and longer apical lamella of the aedeagus.

Description.

BL = 15.8 mm, BW = 5.9 mm. Dorsal side bicolored with strong metallic luster: head and pronotum dark 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 wide and round, PW/PL = 1.39, widest slightly before middle; lateral margins strongly widened and curved near middle, and then strongly constricted to base, PW/PBW = 1.81; lateral margins straight before posterior angles, posterior angles obtuse, forming indistinct angles; anterior margin straight, anterior angles widely rounded; posterior margin with width approximately equal to that of anterior margin, very slightly extended backward at lateral sides. Disc completely glabrous, gently convex; median line fine but clearly defined in middle, gradually shallowed, reaching neither posterior nor anterior margin; basal fovea deep and glabrous, without puncture or wrinkle; inner and outer grooves vaguely defined, partly fused together, region between them deeply depressed, so that basal fovea forms simple depressions.

Elytra oviform, EL/EW = 1.54, widest near posterior third; basal ridge complete, sinuate at inner half; humeral angles rounded, without tooth, intervals fairly convex; striae deeply incised, with fine punctures; parascutellar striae short, apex conjunct to first stria; parascutellar pore present; third interval without setigerous pore; umbilicate series on ninth interval composed of approximately 25 pores, sparse in middle.

Ventral side: Propleuron glabrous, mesoepisternum with dense and coarse punctures; metepisternum short and wide, ML/MW = 0.99, with dense 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 almost along their full length of outer surface, very shallowly 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 approximately 60° (the included angle between apical lamella and axes of basal portion of aedeagus). Apical orifice long and wide, reaching basal fourth of aedeagus, opened dorsally, slightly turned to left; right margin of apical orifice straight, left margin gently sinuate and notched near middle. In lateral view, aedeagus apex slightly bent downwards; ventral margin almost straight; apical lamella slightly thickened near base. In dorsal view, aedeagus apex broadly bent to right side; apical lamella length subequal to its basal width, with an indistinct oblique ridge, apex rounded-truncate, without tooth.

Endophallus (Fig. 8 ) rotated to dorsal-left direction of aedeagus, major portion of endophallus on dorsal side of aedeagus; gpl folded so, invisible in Fig. 8 , bb short, not reaching middle part of endophallus; cp at left margin of apical orifice. Seven distinct lobes recognized: bl moderately large, slightly prolonged, located at base of apical orifice, pointing to apical direction of aedeagus, membranous, without scales; lb-1 small, rounded, located at base of endophallus and left side of apical orifice, pointing to left basal direction of aedeagus, without decorations; lb-2 larger than lb-1, elongate, located at right side of lb-1, pointing to left apical direction of aedeagus, without decoration; la smaller than lb-1, rounded, located at left side of endophallus, with fine scales; al-1 small, rounded, located at right basal side of endophallus, without decoration; al-2 slightly larger than al-1, rounded, located at right apical side of endophallus, decorated with very fine scales; al-3 with same size as al-2, rounded, located at left apical side of endophallus, decorated with fine scales. Apex of endophallus large, elongate, with a list of heavy spines on central surface, and fine scales on other area.

Distribution.

Bamian Shan Mt., Guidong, Hunan. Only known from the holotype.

Etymology.

The specific epithet constricta refers to the narrowly constricted base of the pronotum. It is treated as an adjective in the nominative singular.

Figures

Figures 5 - 8. Trigonotoma constricta sp. nov. 5 Habitus of holotype (male, Hunan, IZAS) 6 labels of holotype 7 median lobe of aedeagus (holotype) A dorsal view B left lateral view 8 endophallus (holotype) A left lateral view B dorsal view C right lateral view D apical view.