Maja orbignyana Millet de la Turtaudière, 1865

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 : 373

Maja orbignyana Millet de la Turtaudière, 1865 ( Fig. 4 A-F)

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.

Maja orbigniana – Couffon 1910: 130, fig. 4. — Schweitzer et al. 2010: 95.

Maia sp. – Via 1932: 9.

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

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

MATERIAL EXAMINED AND MEASUREMENTS (in mm). — One fragment of anterior part of carapace preserving left rostral spine, left orbit and protogastric lobe, MS2012 0 172a: L = 26.3; W = 21. — Three fragments of left orbital region, ULB-SO-3: L = 9.5, W = 16; ULB-SO-3: L = 17, W = 11; ULB-SO-2: L = 19, W = 14.5. — Merus of ambulatory leg ULB-SO-4: L = 23; W = 5. — Dactylus of ambulatory leg ULB-SO-5: L = 21; W = 4.

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

DESCRIPTION

Rostrum bifid with long, conical and acute rostral spines. Orbits shallow, rounded, opened; supraorbital margin with medial, flattened, acute subtriangular tooth, bounded by two fissures, the outer one deepest; outer orbital tooth long, conical, acute, slightly upward directed; inner orbital tooth subtriangular, acute; infraorbital margin with a blunt, prominent inner tooth, separated from the outer lateral orbit margin by a deep fissure. Protogastric region strongly swollen, ornate with strong and raised rounded tubercles. Hepatic region slightly swollen, ornate with rounded granules, the biggest ones at the basis of the hepatic spine, which is conical, acute and laterally directed. Merus of ambulatory leg subcircular in cross section, slightly compressed laterally; dactylus of ambulatory leg conical, subcircular in proximal cross section, slightly compressed distally.

REMARKS

The recovered specimens are fragmentary portions of the left anterior parts of several carapaces (mainly orbits and front). After comparison with images of the holotype ( Couffon 1908: figs 1, 2, 4; 1934: pl. 1, fig. 155), and of the fragmentary left orbit figured there ( Couffon 1908: pl. 1, fig. 3), it is clear that the recovered remains can be attributed to M. orbignyana with confidence. The strong, rounded and raised tubercles in the protogastric lobe and hepatic region are distinctive for the species (see Müller 1993: 13).

Figures

FIG. 4. — A-F, Maja orbignyana Millet de la Turtaudière, 1865: A, ULB-SO-2, frontal view of left orbit; B, MS2012 0 172a, dorsal view of anterior part of carapace; C, ULB-SO-3, frontal view of left orbit; D, ULB-SO-3, frontal view of left orbit; E, ULB-SO-4, merus of ambulatory leg; F, ULB-SO-5, dactylus of ambulatory leg; G-L, Pilumnus mediterraneus (Lőrenthey, 1897): G, ULB-SO-6, dorsal view; H, frontal view; I, MS2012 0 170,frontal view; J, dorsal view; K, ULB-SO-7,left chela; L, ULB-SO-8, left chela. Scale bars: 10 mm. Photographs by À. Ossó.