Stenodactylina delphinensis ( Moret, 1946 ) 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 : 525

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).

Figures

FIG. 5. — Stenodactylina delphinensis (Moret, 1946) n. comb. from the Berriasian of Noyarey, France, holotype OSUG.UJF-ID 11152: A, carapace in dorsal view showing the two sides; B, line drawing of right side. Abbreviations: a, branchiocardiac groove; b, antennal groove; b1, hepatic groove; c, postcervical groove; d, gastro-orbital groove; e1e, cervical groove; i, inferior groove; PoA, post-orbital area. Photograph: L. Cazes. Line drawing: J. Devillez. Scale bars: 5 mm.