Undetermined

Ossó, Àlex, Gagnaison, Cyril & Gain, Olivier, 2022, A re-appraisal of the middle-late Miocene fossil decapod crustaceans of the ‘ Faluns’ (Anjou-Touraine, France), Geodiversitas 44 (6), pp. 207-228 : 222

Undetermined cheliped

( Fig. 6H-J )

Cancer sismondae – Couffon 1908: 5, pl. 2, figs 3-4.

Eriphia? sp . – Glaessner 1933: 6-7, pl. 1, fig. 2.

Undetermined cheliped – Ossó & Gagnaison 2019: 378-379, fig.6E-F.

MATERIAL EXAMINED AND MEASUREMENTS (in mm). — One left cheliped with complete propodus and dactyli, and carpus attached, MNHN.F.B39266: (palm) L = 65.3, H = 31.55, T = 15.80.

LOCALITY AND HORIZON. — Doué-la-Fontaine (Maine-et-Loire), probable Tortonian.

DESCRIPTION

Palm subtrapezoidal, robust, wider than high, higher distally. Outer side convex, surface smooth, five transverse rows of weakly marked spaced spines more pointed proximally. Inner side slightly convex, smooth. Upper margin flattened, with rounded edges, with two rows of spaced spines, irregularly aligned. Lower margin slightly convex, rounded. Dactyli about one third of the length of the chela. Dactylus gently curved with strongly curved spooned tip; upper margin spiny proximally; occlusal margin with four weakly prominent blunt teeth. Index robust, with rounded lower margin; occlusal margin, longitudinally depressed with spooned tip, with three blunt teeth in the outer edge. Carpus rounded subtriangular, robust, surface smooth; armed with spaced spines placed irregularly; inner angle with a prominent spine, and a second spine placed below.

REMARKS Couffon (1908) reported this large left cheliped for the first time and attributed it to Lobocarcinus sismondai (as Cancer sismondae ). Subsequently, Glaessner (1933) examined the cheliped and an additional right chela and discarded its belonging to Cancer , based on the absence of a cutting-edge in that cheliped, pointing out to a possible relationship with xanthids and particularly with Eriphia Latreille, 1817, but with a question mark. Ossó & Gagnaison (2019) discussed on this cheliped, discarding any relationship with Cancridae and avoiding any systematic assignation without prior examination of the specimen. Personal examination of this cheliped at MNHN, also did not clarify a clear identification.However, it cannot be attributed to Eriphia due to the lack of cutting-edge in its dactyli, that Eriphia spp. possess.No remains of carapace have been found in the ‘Faluns’ outcrops, that give us any clue. Nevertheless, the general construction of the cheliped, the weakly spiny in the upper portion of the palm, and the absence of cutting-edge, and the slightly spooned tips of the dactyli, recall that of some species of xanthids, for instance Etisus H. Milne-Edwards, 1834 . Therefore, this cheliped is left as Xanthidae sensu lato, with reservations.

Figures

FIG. 6. — Decapod from the ‘Savignean facies’ (Langhian) of ‘La Sonneterie’ quarry,Meigné-le-Vicomte (Maine-et-Loire):A-C, Necronectes michelini (A. Milne-Edwards, 1861), MHNH-2016-79-2003: A, ventral view; B, view of upper margin of chelipeds; C, frontal view of chelipeds. Decapods from the ‘Savignean facies‘ (Langhian-Serravallian) of the ‘Blandinerie’ quarry, Breil (Maine-et-Loire): D-G, Xantho moldavicus (Yanakevich, 1977): D, ULB-IV-A (6), dorsal view; E, frontal view; F, ULB-IV-A (11), dorsal view; G, frontal view. Decapod from the probable Tortonian of Doué-la-Fontaine (Maine-et-Loire): H-I, Undetermined cheliped MNHN.F.B39266: H, outer margin; I, upper margin; J, inner margin. Scale bars: A-C, 50 mm; D-G, 5 mm; H-J 20 mm. Photographs of: A-C, by P. Saulet; D-J, by À. Ossó.