Calappa saheliensis Van Straelen, 1937

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 : 16-18

Calappa saheliensis Van Straelen, 1937

( Fig. 2 A-D)

Calappa saheliensis Van Straelen, 1937: 473 , 474, pl. 33, fig. 1. — Saint Martin & Müller 1988: 251. — Moissette & Müller 1990: 738. — Mayoral et al. 1998: 508, fig. 2.4. — Díaz-Medina et al. 2017: 181. — Ossó & Gagnaison 2019: 370, 371.

Calappa sahelensis [sic] – Schweitzer et al. 2010: 83.

Calappa cf. saheliensis – Mayoral et al. 1998: 508, fig. 2.3. (non Calappa saheliensis Van Straelen, 1936 ).

TYPE MATERIAL. — Holotype MNHN.F.R03768 and five paratypes MNHN.F.A28898 , A28899 , A28900 , A28901 , A28902 (Arambourg coll.).

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

TYPE AGE. — Late Miocene (late Messinian ).

DESCRIPTION

Carapace

Carapace subovate, strongly vaulted longitudinally and transversely, with spined posterolateral flanges; maximum width at level of third posterolateral tooth; front poorly preserved; orbits small, rounded; supraorbital margin entire; anterolateral margins strongly arcuate; posterolateral margins strongly convex; flange extensions with five triangular teeth: three teeth equal in size, followed by two teeth decreasing in size posteriorly; posterior margin short, slightly convex; carapace surface covered by small tubercles densely arranged uniformly; tubercles more scattered along posterior margin; central regions bounded longitudinally by deep two parallel grooves running from orbits to cardiac region; small tubercle between metagastric and urogastric regions.

DISCUSSION

Van Straelen (1937) reported eight type specimens partially decorticated. The check of the type material highlighted that two paratypes seem to be lost. Though Van Straelen (1937) did not provide a detailed description of this species, he assigned it to Calappa without justification. Based on Schweitzer & Feldmann (2019), we concur with this systematic assignment for the presence of the spined posterolateral flanges.

Regarding the Miocene of the Mediterranean and Paratethys, Calappa is represented by three species, Calappa heberti Brocchi, 1883 , C. praelata Lőrenthey in Lőrenthey & Beurlen, 1929, and C. saheliensis . As pointed out by Díaz-Medina et al. (2017) the last two species are morphologically very close to each other. However, the reappraisal of the type series of C. saheliensis has pointed out that the carapace regions are covered by small tubercles densely and uniformly arranged (versus large tubercles in these regions in C. praelata ). Calappa heberti differs from C. saheliensis in having large tubercles in the anterior half of the carapace and short squamous ridges in the posterior portion. Therefore, based on the different carapace ornamentations, C. saheliensis can be considered as a valid species within Calappa .

Mayoral et al. (1998) reported an incomplete calappid crab from the early Pliocene of Guadalquivir Basin ( Spain) identified as Calappa cf. saheliensis , based on the smooth ornamentation of the posterior part of the carapace. It is difficult, however, to assert that this poorly preserved specimen could be related to C. saheliensis simply for the smooth ornamentation, lacking the main diagnostic characters of this species, such as orbits, antero- and posterolateral margins, urogastric and cardiac regions, and spined posterolateral flanges. In conclusion, we limit the stratigraphic range of C. saheliensis to the late Miocene ( Messinian ).

Figures

FIG. 2. — Brachyurancrabs from thelate Messinian of Oran(Les Planteursquarry,Arambourg coll.):A-D,Calappa saheliensis Van Straelen,1937:A,holotype MNHN.F.R03768, dorsal view;B, paratype MNHN.F.A28898, dorsal view;C, paratype MNHN.F.A28899, dorsal view;D, paratype MNHN.F.A28902, dorsal view;E, F, Wahrania arambourgi (Van Straelen, 1937), n. comb. holotype MNHN.F.R03773, dorsal view and line drawing of carapace. Abbreviations: b, branchiocardiac groove; ca, cardiac region; i, intestinal region; ms, mesogastric region; mt, metagastric region; o, orbit; u, urogastric region; 1, pseudorostral spine (= rostrum); 2, postorbital spine; 3, hepatic spine; 3.1, accessorial spine of hepatic spine;4, epibranchial spine;5, mesobranchial spine;6, 7, metabranchial spines. Scale bars: 1 cm. Photographs: Lilian Cazes.