Cretorabus rasnitsyni Wang & Zhang

Wang, Bo & Zhang, Haichun, 2011, A new ground beetle (Carabidae, Protorabinae) from the Lower Cretaceous of Inner Mongolia, China, ZooKeys 130, pp. 229-237 : 232-233

Cretorabus rasnitsyni Wang & Zhang sp. n. Figs 1-5

Holotype.

NIGP152464, male, a well-preserved beetle in ventral aspect. Yixian Formation, Lower Cretaceous; a fossil locality (41°25'N, 118°57'E) near Yangshuwanzi Village, Bisiyingzi Township, Ningcheng County, Chifeng City, Inner Mongolia, China. Deposited in the Nanjing Institute of Geology and Palaeontology (NIGP), Chinese Academy of Sciences.

Diagnosis.

Body medium-sized. Pronotum 1.8 times as wide as long. Prosternal process almost as wide as procoxae, much longer than procoxae. Metaventrite 3 times as wide as long. Metacoxae 1.8 times as wide as long. Metacoxal plates with lateral part of posterior margin not emarginate.

Description.

Head and pronotum strongly transverse. Length of head (including mandibles) slightly shorter than occiput width. Head capsule narrowing anteriorly from base. Eyes shorter than temples. Gular plate 1.5 times as long as wide, widened anteriorly. Antennae inserted at anterior margin of eyes; scape dilated; pedicellum slightly shorter than scape; first flagellomere slightly longer than scape. Mandibles large, slightly incurved, asymmetrical, with retinaculum small. Maxillary palps 4-segmented, conspicuously longer than mandibles; palpomere 4 with apical margin subtruncate.

Pronotum 1.8 times as wide as long, widest nearly in the middle; pronotal angles pointed, concealing the base of head dorsally. Propleura narrow. Prosternum before procoxae 1.4 times longer than procoxae. Prosternal process wide, 1.4 times as long as procoxae. Mesoventrite transverse, with subtriangular depression for reception of prosternal process. Mesepisternum almost rectangular, transverse. Mesepimeron short, extending to mesocoxal cavities, slightly widened laterally. Metaventrite short, 3 times as wide as long; its anterior margin half as long as the posterior. Metepisterna subtriangular, gradually widened anteriorly, its length 1.5 times width at anterior margin. Metacoxae oblique, slightly projecting over abdomen, 3 times as wide as long. Metacoxal plates slightly longer than coxae. Abdomen a little longer than meso- and metathorax combined, widened from base to apex of second visible sternite, then narrowing. Parameres rather long, with penis slightly projecting.

Profemur and protibia widened apically, almost equal in length. Tarsal segments widened apically; tarsomeres 1 almost as long as tarsomeres 2; tarsomeres 2 slightly longer than tarsomeres 3. Mesofemur and mesotibia almost equal in length. Mesotibia widened apically, 1.2 times as long as protibia. Metatrochanters one-third as long as metafemora. Metatibiae 1.1 times as long as metafemora, slightly widened apically; its outer side possibly with pits.

Measurements.

Body length 7.8 mm, width 4.0 mm. Head length (including mandibles) 1.9 mm, occiput width 2.6 mm; mandible length 0.8 mm. Pronotum: length 1.8 mm, maximal width 3.2 mm. Abdomen: length 3.3 mm. Fore legs: femur length 1.5 mm; tibia length 1.5 mm. Middle legs: femur length 1.7 mm; tibia length 1.7 mm. Hind legs: femur length 2.0 mm; tibia length 2.3 mm.

Etymology.

Specific epithet is devoted to Alexander P. Rasnitsyn, an outstanding Russian palaeoentomologist.

Remarks.

This specimens can be undoubtedly attributed to Cretorabus by the following characters: the pronotum constricted behind middle; mesoventrite longer than mesocoxae; metacoxal plates tapering strongly in lateral half, extending as a narrow tongue up to the lateral margins of metacoxae; and abdomen short, with rounded apex. The species mostly resembles Cretorabus orientalis in having the prosternal process much longer than procoxae, and metacoxae 2.5 times as wide as long, but differs from the latter in possessing the metacoxal plates with the lateral part of the margin not emar ginate. Furthermore, it is different from Cretorabus capitatus in having the comparatively wider prosternal process and metacoxae.