Tethysastacus, Devillez & Charbonnier & Hyžný & Leroy, 2016

Devillez, Julien, Charbonnier, Sylvain, Hyžný, Matúš & Leroy, Lucien, 2016, Review of the Early Cretaceous erymid lobsters (Crustacea: Decapoda) from the Western Tethys, Geodiversitas 38 (4), pp. 515-541 : 536

Genus Tethysastacus n. gen.

( Fig. 1M )

TYPE SPECIES. — Eryma tithonia Van Straelen, 1936 by monotypy.

DIAGNOSIS. — Fusiform intercalated plate; straight ocular incision; wide post-orbital area; wide and deep cervical groove; no gastroorbital groove; wide postcervical groove, straight, strongly inclined, joined to hepatic groove; concave hepatic groove, joined to cervical groove; dense heterogeneous ornamentation, branchial region with small tubercles and small depression, gastric region with pits, frontal region with strong tubercles and pits.

ETYMOLOGY. — A combination of Tethys, the vast Mesozoic ocean, and the Latin astacus (“marine crayfish” or “escrevisse” in Old French).

DISCUSSION

Tethysastacus n. gen. is assigned to the Erymidae based on the presence of the intercalated plate. It differs from all other genera of erymid lobsters by its extremely simple carapace groove pattern and the absence of branchiocardiac and gastroorbital grooves. The postcervical groove is straight, whereas it is inflected in all other genera.

Figures

FIG. 1. — Line drawings of carapaces and P1 chelae of Early Cretaceous erymid lobsters from Western Europe: A-C, Eryma Meyer, 1840: carapace (A), P1 chela form I (B), P1 chela form II (C); D-F, Stenodactylina Beurlen, 1928: carapace (D), P1 chela form I (E), P1 chela form II (F); G-H, Palaeastacus Bell, 1850: carapace (G), P1 chela (H); I-J, Enoploclytia M’Coy, 1849: carapace (I), P1 chela (J); K-L, Pustulina Quenstedt, 1857: carapace (K), P1 chela (L); M, Tethysastacus n. gen.: carapace. Abbreviations: a, branchiocardiac groove; b, antennal groove; b1, hepatic groove; c, postcervical groove; cd, cardiac groove; d, gastro-orbital groove; e1e, cervical groove; i, inferior groove; ip, intercalated plate; PoA, post-orbital area; ω, attachment site of mandibular muscle; χ, attachment site of adductor testis muscle. Line drawings: J. Devillez and S. Charbonnier.