Paralithomerus parallelus, Chang, Huali, Zhang, Fan & Ren, Dong, 2008

Chang, Huali, Zhang, Fan & Ren, Dong, 2008, A new genus and two new species of fossil Elaterids from the Yixian Formation of Western Liaoning, China (Coleoptera: Elateridae), Zootaxa 1785, pp. 54-62 : 58-60

Paralithomerus parallelus sp. nov.

( Figs. 11–15 )

Type specimen: Holotype. CNU-C-LB2006872, an impression of elaterid with almost complete body, but most antennal segments absent, housed in Key Lab of Insect Evolution & Environmental Change, Capital Normal University, Beijing, China.

Locality and horizon. Collected from 2nd Bed of Yixian Formation in Huangbanjigou, near Chaomidian Village, Shangyuan County, Beipiao City, Liaoning Province, China; Upper Jurassic-Lower Cretaceous.

Etymology. Specific name derived from Latin “ parallelus ”, (meaning “parallel”), for the striae of the elytra that are parallel to each other.

Diagnosis. This new species is distinguished from P. exquisitus by the following characters: (1) pronotum width shorter than length if the length is measured at the median line; (2) prosternal process quite short; (3) metepisternum narrow; (4) elytra with 9 distinct longitudinal striae, each stria nearly parallel to the sutural margin, the 3rd and 4th, 7th and 8th not united; and (5) apical ventrite 1.33 times longer than the previous one and broadly rounded apically.

Description. Body subcylindrical, medium sized, with length 12.5 mm, width 4.5 mm, elytron length 7.8 mm; Elytra with nine nearly parallel longitudinal striae ( Figs. 11, 13 , 14 ).

Head sub-triangular, convex; eyes oval, medium sized; mandibles incurved, bidentate at apex; labrum small, transverse ( Fig. 11 ).

Pronotum subtrapezoidal, 2.17 times as long as head, width 1.23 times wider than long; anterior margin arched inside, with short angles, lateral sides slightly arcuate in front of hind angles, basal margin bisinuate, with basal pleural furrow; disc slightly convex, with a mild median longitudinal depression; hind angles acute, produced posteriorly, with distinct short carina ( Figs. 11, 12 ).

Elytra wider than prothorax, 3.45 times as long as wide, with 9 distinct longitudinal striae, each stria nearly parallel to the sutural margin, apex of elytra slightly obtuse; epipleural rim normal ( Figs. 13 , 14 ).

Ventral surface with chin piece normally arcuate; pronotosternal suture double, widely opened anteriorly; procoxal cavities quite small, rounded and separated, open behind; prosternal process short, wedge-shaped; Mesoventrite small, mesoventral cavity circular, mesepimeron subtriangular, mesocoxae open to mesepimeron. Metaventrite and mesoventrite separated by distinct suture, metaventrite relatively long and flat, with longitudinal suture; metepisternum narrow; metacoxal plates slender, obtusely long triangular, evenly narrowed laterally. Abdomen with 5 visible ventrites, narrowed from the base of fifth visible ventrite, apical ventrite 1.33 times longer than ventrite 4 and broadly rounded apically ( Figs. 12 , 15 ).

Legs with procoxa rounded; mesocoxa circular, larger than procoxa, metacoxa transverse ( Fig. 11 ).

Remarks. Although most of the antennal segments are absent, the new species can be assigned to the new genus Paralithomerus based on the following characters: (1) head subtriangular, convex; (2) pronotosternal sutures double, open anteriorly; (3) mesocoxae open to mesepimeron; mesoventrite and metaventrite separated by distinct suture; and (4) metacoxal plates slender, obtusely long triangular, evenly narrowed laterally.

Figures

FIGURES 11 – 13. Paralithomerus parallelus sp. nov., 11 — dorsal view, 12 — prothorax, 13 — apical half of elytron.

FIGURES 14 – 15. Paralithomerus parallelus sp. nov., holotype. 14 — dorsal view, 15 — ventral view.