Tethysastacus tithonius ( Van Straelen, 1936 ) 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

Tethysastacus tithonius ( Van Straelen, 1936) n. comb.

( Fig. 10 A-D)

Eryma tithonia Van Straelen, 1936: 8-9 , pl. 2, fig. 1-2. — Roger 1946: 42. — Secrétan 1964: 68. — Förster 1966: 123. — Feldmann & Titus 2006: 64.

Eryma tithonium – Schweitzer et al. 2010: 25.

TYPE MATERIAL. — Holotype MNHN.F. J03351 .

TYPE LOCALITY. — Laciterne-Boisset near Moulès-et-Baucels, Hérault department, Languedoc-Roussillon region, South France.

TYPE AGE. — Valanginian, Early Cretaceous.

DESCRIPTION

Subrectangular carapace in lateral view (holotype: CL = 21 mm; CH = 10 mm); long, toothless rostrum; intercalated plate present; short, oblique ridge near rostrum basis; straight ocular incision; wide tuberculate post-orbital area; wide, deep cervical groove, probably joined to dorsal margin, joined to antennal groove; antennal groove shallower than cervical groove, reaching post-orbital area; gastro-orbital groove absent; straight, oblique postcervical groove, as wide and deep as cervical groove, joined to hepatic groove; slightly concave hepatic groove, narrower than cervical and postcervical grooves, joined to cervical groove; curved inferior groove, joined to ventral margin behind its junction to hepatic groove, as wide and deep as hepatic groove; branchial, cardiac and hepatic regions with small tubercles intercalated with deep circular pits; similar ornamentation in pterygostomial region but with smaller and shallower pits; cephalic region with heterogeneous ornamentation: gastric region with circular pits, frontal region with strong tubercles and small pits; dense ornamentation on the whole carapace.

COMMENTS

The holotype presents a carapace in butterfly-like position with a strong dorsoventral flattening along the dorsal midline ( Fig. 10A ). This mode of preservation is characteristic of a lobster molt ( Glaessner 1969; Charbonnier et al. 2012b). A pronounced rupture of the dorsal midline is observed with a strong rotation of the two halves of carapace. This suggest a probable hinge-type opening during the ecdysis ( Charbonnier et al. 2012b).

Figures

FIG. 10. — Type material of Tethysastacus n. gen.: A, B; holotype MNHN.F.J03351 of Tethysastacus tithonius (Van Straelen, 1936) n. comb. from the Valanginian of Laciterne-Boisset near Moulès-et-Baucels, France: almost complete right side of carapace and cephalic region of left side of carapace (A), detail of cephalic region showing the wide post-orbital area (B), line drawing of carapace (C) close-up of cephalic region (D). Abbreviations: b, antennal groove; b1, hepatic groove; c, postcervical groove; cam, carina of anterior margin; e1e, cervical groove; i, inferior groove; ip, intercalated plate; PoA, post-orbital area;Sag, S-shaped anterior groove. Photographs: L. Cazes. Line drawings: J. Devillez. Scale bars: 5 mm.