Parahyas oranensis ( Van Straelen, 1937 ) Charbonnier & Garassino & Pasini & Chény, 2024

Charbonnier, Sylvain, Garassino, Alessandro, Pasini, Giovanni & Chény, Cédric, 2024, Review of brachyuran crabs from the late Miocene (Messinian) of Oran, Algeria, Geodiversitas 46 (2), pp. 13-29 : 19-22

Parahyas oranensis ( Van Straelen, 1937) , n. comb.

( Fig. 3 )

Hyas oranensis Van Straelen, 1937: 474 , 475, pl. 33, fig. 2. — Saint Martin & Müller 1988: 251. — Moissette & Müller 1990: 738. — Schweitzer et al. 2010: 97. — Kato et al. 2013: 270, 275-277. — Guinot et al. 2019: 307.

TYPE MATERIAL. — Holotype MNHN.F.R03767 , one paratype MNHN.F.A28903 (Arambourg coll.).

TYPE LOCALITY. — Les Planteurs quarry , Sanaouber district of Sidi El Houari, Oran.

TYPE AGE. — Late Miocene (late Messinian ).

DESCRIPTION

Carapace

Carapace pyriform, convex both longitudinally and transversely, length slightly exceeding width; widest posteriorly; rostrum not preserved; orbit composed of supraorbital rim and widely cup-shaped postorbital spine bearing marginal spines; anterolateral margins poorly preserved; posterolateral margins rounded, bearing row of 6-7 wide tubercles extending along entire length of margin; posterior margin partially preserved; hepatic region depressed; proto-, meso-, and metagastric regions raised; diamond-shaped cardiac region strongly elevated; branchial regions inflated; urogastric and cardiac regions raised and limited laterally by deep branchiocardiac groove; intestinal region protruding distally beyond and under branchial regions; dorsal surface of carapace covered with small tubercles arranged uniformly.

DISCUSSION

Van Straelen (1937) figured only the holotype but the paratype is better preserved and shows some additional characters such as the wide cup-shaped postorbital spine, the well-developed intestinal region beyond and under the inflated branchial regions, and the posterolateral margins with a row of large aligned tubercles.

Extant members of the Oregoniidae are relatively rare in the Mediterranean Basin and only Ergasticus A. Milne-Edwards, 1882 has been reported ( GBIF 2022:https://www.gbif.org/species/4375129). In the fossil record, Hyas meridionalis Glaessner, 1928 was described from the Miocene of Austria, but the type specimen is poorly preserved and, even if it is surely a member of Majoidea , the generic assignment seems to be doubtful. In conclusion, Parahyas n. gen. is most likely the only Mediterranean representative of the Oregoniidae in the fossil record.

Figures

FIG. 3. — Parahyas oranensis (Van Straelen,1937),n. comb.from the late Messinian of Oran (Les Planteurs quarry,Arambourg coll.):A, B, holotype MNHN.F.R03767, dorsal view and line drawing of carapace; C, D, MNHN.FA28903 (ex paratype of Calappa saheliensis Van Straelen, 1937), dorsal view and line drawing of carapace. Abbreviations:b, branchiocardiac groove; br, branchial region;ca, cardiac region;i, intestinal region;mt, metabranchial region; ps, cup-shaped postorbital spine; u, urogastric region. Scale bars: 1 cm. Photographs: Lilian Cazes.