Horologion Valentine, 1932

Harden, Curt W., Davidson, Robert L., Malabad, Thomas E., Caterino, Michael S. & Maddison, David R., 2024, Phylogenetic systematics of the enigmatic genus Horologion Valentine, 1932 (Coleoptera, Carabidae, Trechinae, Horologionini), with description of a new species from Bath County, Virginia, Subterranean Biology 48, pp. 1-49 : 1

Horologion Valentine, 1932

Description.

Small, eyeless, pubescent beetles with short appendages and pedunculate body form. Head with one supraorbital seta on each side and a posterior row of three to five pairs of inwardly curved macrosetae. Mandibles with scrobal seta present, elongate and similar in shape. Clypeus with two pairs of fixed setae. Head with frontal furrows weakly impressed and poorly defined. Labrum with six fixed setae. Ligula with four large fixed setae, inner pair fused. Head ventrally with suborbital seta on each side. Pronotum strongly constricted posteriorly, lacking posterior angles and posterior marginal setae. Elytral humeri modified, with a raised carinate shelf of variable length and shape. Eight umbilicate punctures along margin of elytra, subapical seta (sensu Schmidt et al. 2021) present, not separated from umbilicate series by carinate interval. Apical recurrent stria absent. One discal seta in third elytral interval. Elytral striae poorly defined, shallow and coarsely punctate. Preapical plica present, well developed. Tarsomeres of all legs short and transverse in both sexes. Males with two basal protarsomeres each bearing a row of adhesive setae ventrally, either both markedly expanded and dentate on inner margin ( H. hubbardi ) or with only the first protarsomere moderately expanded and weakly dentate on inner margin ( H. speokoites ). Procoxae closed posteriorly. Mesocoxae conjunct. Mesoventrite elongate and bell-shaped, coarsely sculptured, with median depression flanked by coarsely setose carinae. Metacoxae widely separated. Median lobe of aedeagus open dorsally, membranous along entire dorsal margin and most of ventral face. Internal sac with flagellum present, swollen basally, broadly curved and rotated dorsally so that it appears as a complex sclerotized structure in lateral aspect. Spermathecal duct broad, with abrupt U-shaped bend proximally. Spermatheca small and saclike. Spermathecal gland present and elongate. Gonocoxites slender and glabrous except for a single small seta on inner margin near apex. Tergite of female genital segment strongly sclerotized and forming a V-shaped bridge behind gonocoxites.