Stenodactylina delphinensis (Moret, 1946) n. comb.

(Fig. 5A, B)

Eryma delphinensis Moret, 1946: 49-51, fig. 3. — Förster 1966: 122-123. — Schweitzer et al. 2010: 23.

TYPE MATERIAL. — Holotype OSUG.UJF-ID 11152 (Touchon coll.).

TYPE LOCALITY. — Noyarey, Isère department, Rhône-Alpes region, southeastern France.

TYPE AGE. — Berriasian, Early Cretaceous.

DESCRIPTION

Subcylindrical carapace (holotype: CL = 36 mm; CH = 17 mm); short toothless rostrum; fusiform intercalated plate; slightly curved ocular incision; narrow tuberculate post-orbital area; wide cephalic region, extending at almost half of carapace length; wide, deep cervical groove, strongly inclined, joined to dorsal margin and to antennal groove; narrow antennal groove; short gastro-orbital groove originating as a slight median inflexion of cervical groove; postcervical and branchiocardiac grooves subparallel; deep and narrow postcervical groove, strongly inclined and curved forward, intercepting dorsal margin, interrupted in hepatic region; shallow branchiocardiac groove, as wide as postcervical groove, deeper towards its junction to hepatic groove, not joined to dorsal margin, joined to hepatic groove; narrow, hepatic groove, shallow, concave posteriorly, slightly convex anteriorly, joined to cervical groove; flat attachment site of adductor testis muscle (χ bulge); wide and deep inferior groove, convex posteriorly, joined to hepatic groove; carapace ornamentation made of small tubercles delimited anteriorly by shallow depressions; ornamentation growing more dense towards branchial region.

DISCUSSION

The examination of the holotype reveals the absence of a junction between postcervical and branchiocardiac grooves which remain subparallel until postcervical groove interrupts in hepatic region. This carapace groove pattern is typical of Stenodactylina . Stenodactylina delphinensis (Moret, 1946) n. comb. is the only representative of the genus for the Early Cretaceous. In addition, the holotype presents a carapace in butterfly-like position with a strong dorsoventral flattening along the dorsal midline (Fig. 5A). This layout is characteristic of a lobster molt (Glaessner 1969; Charbonnier et al. 2012b). A rupture of the dorsal midline is observed with a slight rotation of the two halves of carapace. This suggest a probable hinge-type opening during ecdysis (Charbonnier et al. 2012b).