Eryma ventrosum ( Meyer, 1835 )

Charbonnier, Sylvain, Garassino, Alessandro, Gendry, Damien, Devillez, Julien & Picot, Laurent, 2023, The decapod crustacean fauna from the Late Jurassic of Cricqueboeuf, Normandy (France), Geodiversitas 45 (19), pp. 573-588 : 583

Eryma ventrosum ( Meyer, 1835)

( Figs 7 ; 8 )

Glyphea ventrosa Meyer, 1835: 329 .

Eryma ventrosum – Devillez & Charbonnier 2021: 32 , 33-35, figs 3-5 [cum syn.].

TYPE MATERIAL. — Holotype housed at the University of Strasbourg and destroyed by fire in 1967, cast MNHN.F.B12484.

TYPE LOCALITY. — Frétigney, Haute-Saône, Burgundy, France.

TYPE AGE. — Late Jurassic (Oxfordian).

ADDITIONAL EXAMINED MATERIAL. — 89 specimens including nine articulated specimens with partially preserved pereiopods ( MPV 2013.1.288.34, 43, 45, 47, 52, 55, 56, 60, 61). — 46 isolated, more or less complete carapaces ( MPV 2013.1.164.1, 2013.1.288.1, 2, 4-16, 18, 19, 22-24, 27-33, 37, 38, 41, 42, 46, 49, 53, 54, 57-59, 77-83). — Eight pleons with or without telson or tail fan ( MPV 2013.1.288.20, 25, 48, 50, 51, 74, 87, 88). — 16 isolated P1 chelae more or less complete ( MPV 2013.1.288.17, 21, 26, 35, 36, 39, 40, 44, 63, 64, 68, 71, 73, 76, 86, 89). — Five isolated P1 dactylus and index ( MPV 2013.1.288.62, 66, 67, 69, 85). — Five isolated P1 carpomeral articulations ( MPV 2013.1.288. 65, 70, 72, 75, 84). All the samples are from the Oxfordian of Cricqueboeuf, Calvados, Normandy, France.

DESCRIPTION AND DISCUSSION

Devillez & Charbonnier (2021: 34, 36) provided an updated and very complete description of Eryma ventrosum . The specimens from Cricqueboeuf show the fusiform intercalated plate typical of the erymid lobsters and a carapace groove pattern typical of Eryma : cervical groove, strongly inclined dorsally, joined to dorsal margin and to antennal groove; short gastro-orbital groove, originating as a slight median inflexion of the cervical groove; postcervical groove joined to branchiocardiac groove at carapace mid-height; branchiocardiac groove usually strongly inclined, joined to the posterior extremity of hepatic groove; hepatic groove concavo-convex, joined to cervical groove; inferior groove convex posteriorly, joined to hepatic groove and to ventral margin, inflated pleural basis.

The specimens from Cricqueboeuf have a cervical groove slightly inflected, a short gastro-orbital groove, slightly curved postcervical and branchiochardiac grooves, joined at carapace mid-height, a ventral extension of the postcervical groove, an inflated ω area, a dense, fine ornamentation made of tubercles and crescent-shaped depressions, orbital and antennal rows of tubercles, elongated P1 chelae with a subrectangular propodus which is compressed dorso-ventrally, bearing long thin fingers, progressively curved inward, and armed with numerous teeth. In addition, some specimens show rounded stalked eyes with a well-preserved framework of subsquare ommatidia ( Fig. 8B , D-F).All these morphological characters are typical of E.ventrosum , which is well-known in the Callovian-Oxfordian deposits of Normandy ( Devillez & Charbonnier 2021).

Figures

FIG. 7. — Eryma ventrosum (Meyer,1835) from the late Oxfordian of Cricqueboeuf,Normandy:A, carapace MPV 2013.1.288.2,right lateral view;B, carapace MPV 2013.1.288.13,left lateral view;C, carapace MPV 2013.1.288.54, right lateral view; D, carapace MPV 2013.1.288.28,partially enclosed in carbonate nodule, right lateral view; E-G, carapace MPV 2013.1.288.57, interpretative line drawing,right lateral and ventral views; H, carapace MPV 2013.1.288.49, close-up of cephalic region,note the strong orbital and antennal spines;I, carapace MPV 2013.1.288.8,close-up of antennal-pterygostomial and ventral regions.Abbreviations:a, branchiocardiac groove;as, antennal spine;b, antennal groove;b1, hepatic groove;c, postcervical groove;d, gastro-orbital groove; ep, epistome;e1e, cervical groove; i, inferior groove; md, mandible; os, orbital spine; PoA, postorbital area; r, rostrum. Photographs: L. Cazes. Line drawings: S. Charbonnier. Scale bars: 5 mm.

FIG. 8. — Eryma ventrosum (Meyer, 1835) from the late Oxfordian of Cricqueboeuf, Normandy: A-C, subcomplete specimen MPV 2013.1.288.61, right lateral, dorsal, and ventral views; D-F, specimen MPV 2013.1.288.56, cephalic region showing the eyes, dorsal view (D), close-up of stalked-eye (E), close-up of ommatidia network (F); G, specimen MPV 2013.1.288.8, P1 chela, outer view; H, specimen MPV 2013.1.288.39, P1 chela, index and propodus, inner view; I, J, isolated pleon MPV 2013.1.288.50, dorsal and right lateral views; K, specimen MPV 2013.1.288.60, close-up of tail fan. Abbreviations: ip, intercalated plate; o, eye; os, orbital spine; r, rostrum. Photographs: L. Cazes, except (E-F): D. Audo. Scale bars: A-C, G-K, 1 cm; D, 5 mm; E, 1 mm; F, 200 μm.