Xantho moldavicus ( Yanakevich, 1977 )

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 : 221-222

Xantho moldavicus ( Yanakevich, 1977)

( Fig. 6 D-G)

Medaeus moldavicus Yanakevich, 1977: 80 , pl. 10, fig. 4.

Titanocarcinus pulchellus Couffon, 1908: 4-5 , pl. 2, fig. 6, text-fig. unnumbered p. 4.

Titanocarcinus vulgaris Glaessner, 1928: 185 , pl. 3, figs 9-11. — Bachmayer 1953b: 254, pl. 4, figs 1-9, pl. 6, figs 1-2.

Xantho cfr. X. incisus – Müller 1974a: 123, pl. 3, figs 1-2; 1979: 274, pl. 20, figs 1-5.

Xantho cf. X. vulgaris – Förster 1979: 263-264, pl. 5, fig. 4.

Xantho moldavicus – Müller 1984: 92, figs 5-8, pl. 86, figs 1-5, pl. 87, fig. 1.

Xantho cf. moldavicus – Friebe 1987: 61, pl. 2, fig. 5.

Xantho moldavicus – Vía 1988: 351. — Solé & Via 1989: 35. — Marras & Ventura 1991: 110, pl. 2, fig. 2. — Müller 1996: 11, pl. 2 fig. 6; 1998: 34. — Radwański et al. 2006: 96, pl. 2, figs 5, 6. — Gatt & De Angeli 2010: 1339, figs 8G-K. — De Angeli et al. 2011: 114-115, fig. 6. — Ossó & Stalennuy 2011: 37, figs 3.11-12, 9.1-2. — Górka et al. 2012: 171, fig. 21D. — Hyžný et al. 2014b: 226, pl. 1, fig. 6. — Górka in Wysocka et al. 2016: 379, fig. 14F-G. — Hyžný 2016, text-fig. 14F, G. — Ferratges 2017, pl. 33, fig. B. — Górka 2018: 528-529, text-fig. 8.3-8.4a-b. — Hyžný & Dulai 2021: 245-247, figs 98.1-11.

MATERIAL EXAMINED AND MEASUREMENTS (in mm). — One almost complete carapace, ULB-IV-A (6): L = 9.5, W = 14, FOW = 8.5. — Right half of carapace, ULB-IV-A (11): L = 14.5, W= 12.

LOCALITY AND HORIZON. — ‘Blandinerie’ quarry, Breil (Maine-et-Loire). ‘Savignean facies’, Langhian (middle Miocene).

DESCRIPTION

Carapace transversely subhexagonal, regions well marked, surface rugose; ratio length/width about 0.67. Front straight, bilobed, medial notch, edges granulated.Orbits complete,small,rounded, forwardly directed; supraorbital margin finely granulate with two fissures, one of them medially placed, the other close to the outer-orbital tooth; inner orbital tooth acute triangular,separated from the frontal lobe by a deep notch, outer orbital tooth blunt triangular; infraorbital margin, visible dorsally, finely granulate ends in a produced tooth. Ratio fronto-orbital margin/width about 0.60. Anterolateral margin bearing four subtriangular teeth with serrated margins, the fourth the smaller. Posterolateral margins straight, rounded in section. Posterior margin incomplete, rim of small granules. Frontal region divided medially by groove. Protogastric region swollen, anterior portion of lobes divided medially, the inner part confluent with epigastric lobes. Mesogastric region slightly swollen, slender anteriorly, broader rhomboidal posteriorly. Metagastric region not differentiated from mesogastric region.Urogastric region very narrow, separated from meso- metagastric by a groove with two gastric pits visible. Cardiac region broadly T-shaped, slightly swollen, laterally confluent with metabranchial lobes. Intestinal region narrow, transversely swollen, medially depressed. Epibranchial region transversely elongate, sigmoidal, bearing three lobes, the inner one smaller, the medial is separated from the distal lobe that ends at the epibranchial tooth, by an oblique groove. Mesobranchial region short, laterally placed, confluent with the distal lobe of epibranchial lobe. Metabranchial region broad, swollen, separated from epi- and mesobranchial regions by transverse grooves. Hepatic region slightly swollen. All regions covered by granules or rows of granules giving a rugose or squamous aspect. Cervical, branchiocardiac and accessory grooves delimiting regions and lobes well marked but shallow, smooth. Sterno-pleonal elements and appendages not preserved.

REMARKS

Ossó & Gagnaison (2019: 378, figs 5F-I), reported two left chelae likely referable to Xantho moldavicus , but without carapace remains, they left them in open nomenclature. Likewise, they suggested that the specimen figured by Couffon (1908: t. 2, fig. 6, text-fig. unnumbered), from Doué-la-Fontaine, could actually be a sample of Xantho moldavicus , which is confirmed by the new materail herein described, which fits perfectly with the carapaces described and depicted in the literature (e.g. Yanakevich 1969: pl., fig. 6; Müller 1984: pl. 86, figs 1-2, 4, pl. 87, fig. 1; Ossó & Stalennuy 2011: fig. 3, 11-12; Górka 2018: text-fig. 8.3, 4a-b).

Xantho moldavicus is widely present in middle/upper Miocene outcrops of the Central Paratethys and the Mediterranean (see Górka 2018: 530 and references therein). The occurrence of Xantho moldavicus in the Miocene of the ‘Faluns’, extends the presence of this species to the northeastern Atlantic waters, in a similar palaeogeographic distribution and environments of the extant representatives (e.g. Drach & Forest 1953; Reuschel & Schubart 2006)

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.