Priacma latidentata, Tan, Jingjing, Ren, Dong & Shih, Chungkun, 2006

Tan, Jingjing, Ren, Dong & Shih, Chungkun, 2006, First record of fossil Priacma (Coleoptera: Archostemata: Cupedidae) from the Jehol Biota of western Liaoning, China, Zootaxa 1326, pp. 55-68 : 57-59

Priacma latidentata sp. nov.

( Figs. 1 , 5–9 , 24 )

Diagnosis. P. latidentata sp. nov. differs from P. serrata in the absence of spines on edge of elytra, from P. corrupta in the mesosternum of new species without cross suture, from P. longicapitis and P. oculata in the ventral head surface of new one without grooves for inserting antennae, from P. striata in the elytron of new one without paler flecks, from P. sanzii in new one’s pedicel shorter than third antennomere. P. latidentata sp. nov. is distinct from P. tuberculosa sp. nov. in having wide and flattened mandibles with tridentate in apex, connected posterior pair of tubercles on the dorsal of head, and margin of elytral cells without black macula, from both P. renaria sp. nov. and P. c l a v a t a sp. nov. in having markedly shorter pedicel.

Description. Body length 11.0 mm, body width 3.0 mm, elytron length 8.0 mm. Medium­sized and subcylindrical beetle, covered with tubercles ( Fig. 1 ).

Head slightly wider than long, subtriangular, bearing two pairs of tubercles, anterior pair of tubercles at base of antennae, conical, small, posterior ones sub­elliptic, connected to each other, larger than anterior pair; eyes medium­sized; mandibles prominent, wide, apex flattened, tridentate in apex ( Figs. 5 , 8 ), cervical constriction distinct.

Antennae filiform, with 11 segments, less than half as long as entire insect, pedicel 0.4 times as long as third antennomere ( Figs. 5 , 8 ), following antennomeres homonomous.

Pronotum transverse, wider than head, narrowed posteriorly, 1.4 times as wide as long at posterior edge, anterior margin nearly straight, anterior angles sharp ( Figs. 5 , 8 ), oblique, without propleuron, disc of pronotum bearing two circle elevations; scutellum linguiform.

Elytra about 1.5 times as wide as prothorax, 4 times as long as wide, with 10 rows of cells, elytral cells quadrate, angular rounded, without black macula on their margins ( Figs. 7 , 24 ), elongate in distal part of elytron, approximately 34 cells formed in a row.

Ventral surface ( Fig. 6 ) with gula rectangular, reaching posterior ridge of the head, widening posteriorly, genae widely separated ventrally. Prosternal process extending beyond coxae. Metaventrite oblong, 1.2 times as wide as long (at posterior margin), with well expressed longitudinal and transverse sutures ( Fig. 9 ). Abdomen with 5 visible ventrites superimposing each other, first visible abdominal ventrite as long as last one, both of them longer than other visible ventrites, last visible ventrite 2 times as long as previous one, its apex rounded.

Legs ( Fig. 6 ) with procoxae rounded, small, protrochanter subtriangular, protibiae longer than profemora, protarsi five­segmented, first tarsomere as long as last one, both of them longer than other three tarsomeres, other tarsomeres short, equal in size; mesocoxae rounded, large, mesotrochanter small, oblong, mesofemora thin, long, mesotibiae nearly as long as mesofemora, mesotarsi five­segmented, first tarsomere longest, following four tarsomeres homonomous.

Holotype. Nearly complete adult, No. CNU –C–LB2005010 deposited in the Key Lab of Insect Evolution & Environmental Changes, College of Life Science, Capital Normal University in Beijing, China.

Locality and horizon. Collected near Chaomidian Village, Beipiao City, Liaoning Province, China; the Yixian Formation, Late Jurassic­Early Cretaceous (Late Tithonian to the Berriasian).

Etymology. The specific epithet derives from the Latin adjectives latus, ­ a, ­ um (broad, wide) and dentatus, ­a, ­um (toothed, having teeth). It refers to the broad mandibles of the beetle with flattened apices.

Figures

FIGURES 1 – 4. Habiti of new Priacma species, photographs of rock impressions. 1 — Priacma latidentata sp. nov., 2 — Priacma tuberculosa sp. nov., 3 — Priacma clavata sp. nov., 4 — Priacma renaria sp. nov.

FIGURES 5 – 7. Priacma latidentata sp. nov., holotype. 5 — dorsal view, 6 — ventral view, 7 — outline of elytral cells.

FIGURES 8 – 9. Priacma latidentata sp. nov., holotype. 8 — head, 9 — metaventrite.

FIGURES 22 – 25. 22 — head of Priacma renaria sp. nov., 23 — metaventrite of Priacma renaria sp. nov., 24 — elytral cells of Priacma latidentata sp. nov., 25 — elytral cells of Priacma renaria sp. nov.