Xantho cf. moldavicus ( Yanakevich, 1977 )

Ossó, Àlex & Gagnaison, Cyril, 2019, An appraisal of the Middle-Late Miocene fossil decapod crustaceans of the ‘ Faluns’ (Anjou-Touraine, France), Geodiversitas 41 (9), pp. 367-383 : 378

Xantho cf. moldavicus ( Yanakevich, 1977) ( Figs 5 F-I)

MATERIAL EXAMINED AND MEASUREMENTS (in mm). — Two left chelae, ULB-SO-11: L = 6, W = 12; ULB-SO-12: L = 11, W= 21.5.

LOCALITY AND HORIZON. — ‘La Sonneterie’ quarry, Meigné-le- Vicomte (Maine-et-Loire). ‘Savignean facies’, Langhian-Serravallian (Middle Miocene).

DESCRIPTION

Propodi transversely elongate, stout. Palm of left propodus subtrapezoidal, slightly wider than high; maximum height at the distal end. Upper margin straight, flattened, rugose. Lower margin gently convex. Outer side convex, with longitudinal rugose ridges; transverse stepped depression parallel to the upper margin, about to the three quarters of the total height. Inner side obliquely convex distally and concave in the upper proximal corner. Dactyli slightly shorter than palm; dactylus gently curved downwards with a blunt keel in upper margin, and occlusal margin with six or seven subequal triangular teeth; pollex straight, stout, lower margin slightly convex, transverse lateral keel and groove, with occlusal margin with seven or eight subtriangular teeth, the biggest ones in the middle. Tip of both dactyli spoon like. Setal pits visible.

REMARKS

We have not found carapace remains of Xantho moldavicus among the recovered decapod remains in the ‘Faluns’ outcrops, though the specimen figured by Couffon (1908: pl. 2, fig. 6) as Titanocarcinus pulchellus could to be referred to this species. In any case, the chelae examined match exactly the chelae of X. moldavicus described and depicted in the literature (e.g. Müller 1984a: pl. 86, figs 5-8, pl. 86, figs 3, 5; Ossó & Stalennuy 2011: fig. 9, 1-2; Górka in Wysocka et al. 2016: fig. 14G). Furthermore, the typically spooned occlusal surface of the dactyli tips, would allow us to assign, those chelae to the aforementioned species. A successful search of this specimen in the museum collections would confirm the assignation of both, the Couffon’s carapace and the chelae reported herein to X. moldavicus. Meanwhile, in absence of complete carapaces, or remnants of them, with which to relate the chelae, we prefer to leave them in open nomenclature.

Figures

FIG. 5. — A, B, Liocarcinus sp., MS2012 0 172b: A, dorsal view; B, frontal view; C, D, Necronectes michelini (A. Milne-Edwards, 1861): C, ULB-SO-9, right dactylus; D, ULB-SO-10, left dactylus; E, Paguristes gagnaisoni Gagnaison, 2012, MS2006 FS 134b, right chela; F-I, Xantho cf. moldavicus (Yanakevich, 1977): F, ULB-SO-11, left chela, inner lateral view; G, outer lateral view; H, ULB-SO-12, left chela, outer lateral view; I, frontolateral view; J-M, undetermined chelae: J, ULB-SO-13, lateral view of right chela; K, frontal view; L, ULB-SO-14, lateral view of left chela; M, close-up showing an encrusted colony of bryozoans. Scale bars: A, B, 5 mm; C-M, 10 mm. Photographs by À. Ossó.