Trachys semicircucollis Peng, 2024

Peng, Zhongliang, 2024, Studies on the Genus Trachys Fabricius from China (5) - Descriptions of Two New Species (Coleoptera: Buprestidae: Agrilinae: Tracheini), The Coleopterists Bulletin 78 (1), pp. 76-80 : 76-78

Trachys semicircucollis Peng , new species zoobank.org/ urn:lsid:zoobank.org:act:A9D3447B-0A29-493A-98B9-38F64D0E8BC6 ( Figs. 1–5 ) Chinese Common Name: Njfi潜吉丁

Type Specimen. Holotype ( BPCQ), male, labeled: “ Tianjingshan National Forest Park , 24°34ʹN 112°56ʹE, Luoyang, Ruyuan, Guangdong, China, 06-V-2023, Leg. Z-L. Peng et Y-Q. Cai, 广东省乳 ⁂县洛Dffik井山国Ẏƛff公园 ”.

Description. Habitus ( Fig. 1 ): Length 2.90 mm, width 1.60 mm; both dorsal side and underside uniformly bronze-brown with slightly golden reflections; a relatively small species. Head ( Fig. 4 ): Widely excavated between eyes; vertex transversely and arcuately flattened; frons depressed along midline with an indistinct groove, uniformly covered with ocellate sculpture and irregularly clothed with dense, pale yellow pubescence; eyes nearly reniform, inner margins biarcuate and strongly carinate; antennal sockets situated just above lower margins of eyes, subcircular and deep, widely open near sides; clypeus golden-bronze, metallic and shiny, 2.30 times as long as wide, anterior margin semicircularly emarginate, clypeal suture upwardly arcuate, lateral margins inwardly arcuate, surface covered with dense transverse wrinkles; two circular frontal pits situated just above clypeus on each side; antenna short, barely reaching anterior margin of pronotum when laid alongside; antennal scape and pedicel moniliform, 1.50 times as long as wide; antennomeres 3–6 cylindrical, much shorter than scape and pedicel, slightly shorter than remaining apical ones, 1.80 times as long as wide; antennomeres 7–11 serrate; base of head much narrower than anterior margin of pronotum, lateral margins oblique. Pronotum: 2.80 times as wide as long, widest just before base, basal margin 1.56 times as wide as anterior margin in dorsal view but narrower than elytra at base and much narrower at elytral humeri; lateral margins nearly semicircular, tips of basal angles angulate; anterior margin biarcuate, median lobe slightly produced forwards; outer basal edge trisinuate, inner basal edge indistinct; disc convex medially, uniformly covered with scaly or ocellate sculpture, nearly uniformly clothed with mainly pale yellow pubescence mixed with a few brown-yellow setae but nearly glabrous in middle. Scutellar shield: Very small but clearly visible, triangular, smooth. Elytra: 1.45 times as long as wide, 4.20 times as long as pronotum, widest at humeri; lateral margins arcuate from base to humeri, slightly emarginate from behind humeri to posterior third, then rather sharply attenuate to subapices and arcuately to apices; apices jointly arcuate without distinct apical and lateral denticles; elytral surface convex; humeri projecting beyond elytral outline; basal depressions wide and deep; entire surface nearly uniformly covered with small foveae, coarser and denser near suture; elytral ornamentation consisting of mainly white pubescence mixed with a few pale yellow setae, arranged on each elytron as a wide spot at humeral depression, a strip near lateral margin, a spot at basal third near suture, and two transverse bands on apical half with some extra pubescence at apex. Lateral view ( Fig. 2 ): Thickest point lying at basal third of elytra, maximal thickness slightly exceeding length of pronotum plus head; curvature with angle of 125° between pronotal margin and subhumeral lobe; lateral margin of pronotum slightly biarcuate; basal part of elytral margin rather obliquely straight, angulate above metaventrite, humeral carina weak or indistinct. Underside ( Fig. 3 ): Nearly uniformly covered with short, pale pubescence; anterior part of prosternum transverse, nearly rectangular, posterior margin slightly oblique each side; anterior margin transversely straight; prosternal process dumbbell-like, 1.70 times as long as wide, widest at apical angles; apical angles rather arcuate, lateral margins slightly narrowed at apical third; apical margin arcuate, surface very smooth and scattered with a few pale setae; hypomeron uniformly and densely covered with reticulate or wavy microsculpture but without depressed hypomeral marking; mesoventrite completely divided by prosternal process; metaventrite uniformly covered with coarse foveae centrally, with strong reticulate or arcuate wrinkles near anterior margin and towards sides; anterior margin deeply and semicircularly emarginate; first abdominal ventrite covered with strong longitudinal wrinkles, remaining ventrites nearly uniformly covered with reticulate or wavy microsculpture; margins of both anal ventrite and pygidium arcuate. Legs: Procoxa and mesocoxa globular, posterior coxa expanded as a transverse plate and covered with dense ocellate sculpture; all trochanters small, nearly triangular; all femora moderately dilated; all tibiae slender and rather straight with sparse, pale yellow pubescence; all tarsi lobate, completely red-yellow; each claw long and brown with a very short but sharp tooth at base. Aedeagus ( Fig. 5 ): Length 0.70 mm, width 0.23 mm; brownyellow; phallobase narrow but relatively long, much narrower than parameres at base, length 0.28 times total aedeagal length; tegminal strut rather short, apical margin angulate; parameres gradually diverging from base to apical fourth, then arcuately converging to apices; median lobe very wide, strongly sclerotized apically and laterally, membranous centrally. Sexual dimorphism: Female unknown.

Differential Diagnosis. This species is unique and can be distinguished from any other species of the genus by its semicircular pronotal margin and by the hypomeron without depressed hypomeral marking.

Etymology. The specific epithet is an adjective based on the combination of two Latin words, the Latin adjective “semicirculatus”, meaning semicircular, and noun “collum”, meaning neck. It refers to the semicircular shape of the lateral margins of pronotum in this species.

Figures

Figs. 1–10. New species of Trachys, holotypes. T. semicircucollis, new species, male, 2.9 mm: 1) Dorsal view; 2) Lateral view; 3) Ventral view; 4) Head, frontal view; 5) Aedeagus (fully dissected). T. langyashancola, new species, male, 2.5 mm: 6) Dorsal view; 7) Lateral view; 8) Ventral view; 9) Head, frontal view; 10) Aedeagus (fully dissected).