Maja orbignyana Millet de la Turtaudière, 1865

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 : 216

Maja orbignyana Millet de la Turtaudière, 1865

( Fig. 4H-M )

Maia orbignyana Millet de la Turtaudière, 1865: 577 . — Millet 1854: 152 (nomen nudum). — Couffon 1934: 171, fig. 155.

Maja orbignyana – Couffon 1908: 2, 3, pl. 1, figs 1-4. — Glaessner 1929: 247. — Ossó & Gagnaison 2019: 373, figs 4A-F.

MaÏa orbigniana – Couffon 1910: 130, fig. 4.

Maia sp . – Vía 1932: 9.

Maia cfr. orbignyana – Vía 1941: 118, 119, pl. 10, fig. 70.

Maja cf. orbigniana – Müller 1993: 13, fig. 6E.

MATERIAL EXAMINED AND MEASUREMENTS (in mm) (length measurements taken from the basis of the pseudorostral spines). — Two complete carapaces, ULB-IV-A (1): L = 23; W = 17.5. — ULB-IV-A (2): L = 22.5; W = 17.5. — Five fragments of carapaces, ULB-IV-A (23): L = 22.5; W = 22. — ULB-IV-A (24): L = 21; W = 17. — ULB-IV-A (27): L = 22; W = 18. — ULB-IV-A (28): L = 17; W = 18. — ULB-IV-A (29): L = 22; W = 18.5.

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

DESCRIPTION

Carapace pyriform with spiny outline, longer than wide, strongly vaulted transversely; regions well defined, inflated; surface coarsely tuberculate except in the cervical and gastrohepatic grooves. Front narrow with two long, sharp and conical pseudorostral divergent spines. Orbits shallow, rounded, opened; supraorbital eave broad, strongly vaulted; antorbital spine sharp, laterally directed; intercalated spine subtriangular, short; postorbital spine the longer, sharp, conical, obliquely and slightly upwardly directed; suborbital tooth blunt. Hepatic spine short, laterally directed. Lateral margins with three sharp spines laterally directed. Frontal and epigastric regions defined by two rows of tubercles, separated by a shallow groove, that end at the base of the pseudorostral spines. Gastric process raised over the other regions. Proto-, meso- and metagastric regions strongly swollen, weakly differentiated between them; mesogastric lobe defined by longitudinal rows of coarse rounded tubercles, with medial spine; metagastric lobe with sharp spine; protogastric lobes sloping laterally, with scattered tubercles. Urogastric region transversely narrow, slightly swollen, with prominent tubercles; separated from metagastric lobe by cervical groove. Cardiac region swollen, rhomboidal elongate, prominent sharp central spine. Branchial regions strongly swollen, indistinct, sharp branchial spine upward and laterally directed at posterior part. Intestinal region not preserved. Hepatic region slightly swollen, ornate with rounded granules, the biggest ones at the basis of the hepatic spine. Interantennular spine prominent. Basal antennal article broad with two distal spines.

REMARKS

Two almost complete small carapaces, and remains of anterior pars of carapace of five larger specimens, allows us to attribute them all with confidence to Maja orbignyana (cf. Couffon 1908: figs 1, 2, 4). Likewise, the new material preserves elements not described previously such as, some cephalic appendages and frontal spines, which allows a more detailed description of the species ( Fig. 4K, M ). A clear distinction between Maja orbignyana and M. biaensis Lőrenthey in Lorenthey & Beurlen, 1929, can be established not only by the strong, rounded and raised tubercles in the protogastric lobes and hepatic regions in the former (see Müller 1993: 13), but also by the more distinct branchial regions in the latter (see Müller 1993: pl. 48, figs 1-6, t. 49, fig. 1). The general shape and the conformation of the regions of Maja orbignyana , strongly recalls those of the extant M. crispata Risso, 1827 , which, like the fossil species, inhabits the Mediterranean and the Atlantic coast of Europe (e.g. Ng & Richer de Forges 2015: 126-127, fig. 6A-B).

Figures

FIG. 4. — Decapod from the Tortonian of the ‘ Noyant-la-Plaine’ quarry, Doué-la-Fontaine (Maine-et-Loire): A-C, Lobocarcinus sismondai (von Meyer, 1843), ULB-IV-A (3): A, dorsal view; B, close-up of front in dorsal view; C, close-up of front and orbits in frontal view. Decapods from the ‘ Savignean facies‘ (Langhian) of the ‘Blandinerie’ quarry, Breil (Maine-et-Loire): D, E, Hebertides jurassica Guinot, De Angeli & Garassino, 2007, ULB-IV-A (5): D, left lateral view; E, dorsal view; F, G, ‘Ebalia’ cf. hungarica Müller, 1974a, ULB-IV-A (7): F, frontal view; G, dorsal view; H-M, Maja orbignyana Millet de la Turtaudière, 1865: H, ULB-IV-A (1), dorsal view; I, ULB-IV-A (2), left lateral view; J dorsal view; K, ULB-IV-A (23), frontal view; L, dorsal view; M, ventral view. Abbreviations: ab, basal antennal article; dsab, distal spines of basal article; ias, interantennular spine; iot, infraorbital tooth. Scale bars: A-E, H-M, 10 mm; F, G, 5 mm. Photographs by À. Ossó.