Psacodromeus recta Lee, Nam & Park, 2024, sp. nov.
Creators: name: Lee, Soo Bin
name: Nam, Gi Soo
name: Park, Jong Kyun
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Trachypachidae
Psacodromeus
Psacodromeus recta

description: Psacodromeus recta sp. nov.
Material. Holotype KNUL-1114-106, Paratype KNUL-1114-109
Etymology. The species name recta is derived from the Latin word recta, meaning straight.
Locality and horizon. Sacheon-si, Sanam-myeon, Gyeongsangnam-do, Republic of Korea; Jinju Formation, Early Cretaceous, Albian
Diagnosis. Lateral margin of the pronotum straight; the anterior margin of the pronotum is extremely narrower than the posterior margin.
Description. Body lengths ranging from 6.3 mm (KNUL-1114-109) to 9 mm (KNUL-1114-106) and widths from 3.5 mm (KNUL-1114-106) to 5 mm (KNUL-1114-109). Head narrowed anteriorly, with a rounded basal edge; anterior edge of labrum rounded; maxillary palp with three segments, third one slightly wider than others; antennae long, with 11 antennomeres.
Pronotum wider posteriorly, with lateral outer margins straight; posterior margin concave, but the middle partly protruding, pronotum with an overall tetragonal shape; prosternum almost straight posteriorly and contiguous with procoxae; prosternal process short and contiguous with mesoventrite, mesoventrite large, resembling an inverted triangle, with anterior margin pulled posteriorly in middle and posterior margin slightly pulled anteriorly in middle; metepisternum anteriorly large and extremely narrowed posteriorly; metepimeron roughly square-shaped, with posterior part slightly wider than anterior one; epipleuron thick; elytra oval and narrowed posteriorly; no striae or punctures on elytra; prolegs preserved with procoxae and profemora in KNUL-1114-106; profemora poorly preserved in KNUL-1114-109; procoxa polygonal, profemur slightly narrower distally, but with a straight overall outer margin; midleg preserved in KNUL-1114-106, including mesocoxa, mesofemur, and a part of mesotibia; mesocoxa rounded to polygonal and larger than procoxa; mesofemur wide distally, with widest part at middle; mesofemora poorly preserved in KNUL-1114-109; hindlegs preserved in both KNUL-1114-106 and KNUL-1114- 109; metacoxal plate elongated laterally and meeting epipleuron; metacoxae large and polygonal; metafemur widest anteriorly and slightly narrowed distally; metatibia almost straight, widest at distal end; metatarsus with five segments.
Remarks. The overall morphology of KNUL-1114-106 and KNUL-1114-109 are showing the features of the family Trachypachidae including: 1) head narrower than prothorax; 2) Antennae inserted between eyes and base of mandibles; 3) antenna filiform and formed with 11 antennomeres; metacoxae extended laterally, meeting with lateral margins of body (Ball, 2000).
The overall body shape of KNUL-1114-106 and KNUL-1114-109 is teardrop-shaped. The head is narrowed anteriorly, with a triangular shape. The anterior edge of the pronotum is rounded and sharp. These features are diagnostic for the genus Psacodromeus (Ponomarenko, 1977). Most species of Psacodromeus (P. crassus, P. gutta, P. ovalis, and P. rugosus) have been discovered from the Jurassic of Kazakhstan (Ponomarenko, 1977). Only P. minor has been discovered from the Gurvaneren Formation in Mongolia, which is dated as Early Cretaceous, Aptian (Ponomarenko, 1986). P. recta sp. nov. is differ from the P. minor that 1) lateral margin of the pronotum is straight (rounded in P. minor) and 2) width of anterior margin of pronotum noticeably narrower than the posterior margin (slightly narrower in P. minor).
description: Published as part of Lee, Soo Bin, Nam, Gi Soo & Park, Jong Kyun, 2024, Cretaceous beetles from Jinju Formation: Trachypachidae (Coleoptera: Adephaga), pp. 94-106 in Zootaxa 5562 (1) on pages 98-99, DOI: 10.11646/zootaxa.5562.1.12, http://zenodo.org/record/14595661