Maurocarpilius binodosus, Ossó & Gagnaison & Bailleul, 2020

Ossó, Àlex, Gagnaison, Cyril & Bailleul, Julien, 2020, First report of Early Eocene Decapods in Morocco: description of a new genus and a new species of Carpiliidae (Decapoda: Brachyura) with remarks on its paleobiogeography, Geodiversitas 42 (4), pp. 47-56 : 52-53

Maurocarpilius binodosus n. gen., n. sp. ( Fig. 3 )

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MATERIAL AND MEASUREMENTS (IN MM). — Holotype. ULB-IV- A(1a), L = 17; W = 23; FOW = 12.5; F = 7.

Paratypes. ULB-IV-A(1b), L = 16; W = 23; FOW = 11; F = 6.5. — ULB-IV-A(1c) (deformed), L = 19.5; W = 25.5; FOW = 13; F = 7.5.

TYPE LOCALITY AND HORIZON. — Tamalout section, northern face of the Jbel Talouit, North of Kelâa M’Gouna (East of Ouarzazate, Maroc). Ait Ouarhitane Formation, Ypresian (early Eocene).

ETYMOLOGY. — In allusion to the two anterolateral nodes of the anterolateral margin.

DIAGNOSIS. — As for the genus.

DESCRIPTION

Carapace transversely ovate, wider than long, L/W ratio about 0.72; surface of carapace smooth. Carapace vaulted transversely, strongly vaulted longitudinally in the anterior part of carapace. Maximum width at half-length of carapace, between the first and second (epibranchial) anterolateral teeth. Front strongly downturned, bilobed, slightly rimmed, forms a very flattened inverted isosceles triangle; the two median lobes, with the inner orbital lobes, gives a quadrilobate appearance; slightly arched and produced in dorsal view. Orbits small, rounded, supraorbital margin entire, slightly rimmed only at the inner half of the supraorbital margin; inner orbital tooth blunt, outer orbital tooth short, acute subtriangular; visible dorsally. Anterolateral margin largely convex, acute, bearing two small nodes, one at half-length level, weakly visible, and a second more prominent (epibranchial tooth) at posterolateral junction. Posterolateral margin concave, entire, acute rounded rim in anterior half, starting about 60° respect to the axis. Posterior margin slightly convex. Regions not defined; cardiac region bounded by the branchiocardiac grooves. Gastric pits visible. Branchiocardiac grooves defined by muscle scars. Ventral features and appendages no preserved.

REMARKS

The dorsal carapace and the general outline of Maurocarpilius binodosus n. gen., n. sp., greatly recall several species present in the early Eocene, which present unarmed anterolateral margins and a smooth carapace, but differing, however, in the absence or presence of subtle, but distinctive characters, that precludes a congeneric relationship.

For instance, Braggicarpilius marginatus Beschin, Busulini & Tessier, 2015 , from the Ypresian (early Eocene) of northern Italy, differs from the new species by its more produced front, completely unarmed and rimmed anterolateral margin, and convex posterolateral margins. In contrary, Maurocarpilius binodosus n. gen., n. sp. presents two anterolateral nodes and

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their posterolateral margins are clearly concave ( Beschin et al. 2015: 82, fig-text. 11, t. 5, fig. 1; Schweitzer et al. 2018: 3, fig. 3.1; Fig. 4A ). Carpilius petreus Beschin, Busulini, De Angeli & Tessier, 2007, from the middle-late Ypresian of northern Italy, differs from the new species because presents only one anterolateral tooth (epibranchial), instead of two in Maurocarpilius binodosus n. gen., n. sp., and by the presence of the short oblique carina, typical for the genus, that extends from that tooth to the dorsal surface, which is absent in the new species, and in having a shorter posterior margin ( Beschin et al. 2007: 41-42, pl. 7, fig. 7a-b, 8a-b; Fig. 4B ). Eocarpilius ortegai Artal & Van Bakel, 2018, from the Ilerdian (early Ypresian) of northeastern of the Iberian Peninsula, presents a different L/W ratio, about 0.77/080 vs 0.73 in the new species. As well, their anterolateral margins are unarmed, with only a small node at the anterolateral/posterolateral angle, and its dorsal surface is densely covered by small granules, instead of the two clear anterolateral nodes and completely smooth dorsal surface of Maurocarpilius binodosus n. gen., n. sp., which makes the difference between the two species ( Artal & Van Bakel 2018: 30-34, figs 3-6; Fig. 4C, D ). Oscacarpilius rotundus Artal & Van Bakel, 2018, also from the Ilerdian of northeastern of the Iberian Peninsula, shows a very similar dorsal and outline pattern than Maurocarpilius binodosus n. gen., n. sp., however, differs from the latter in having a different L/W ratio, 0.80 vs 0.73, completely entire antero- and posterolateral margin, without nodes or sharp angles and by its dorsal surface pitted ( Artal & Van Bakel 2018: 23-29, figs 1-2; Fig. 4E, F ).

Figures

FIG. 3. — Maurocarpilius binodosus n. gen.,n.sp.,from the Ypresian (early Eocene) of Kelâa M’Gouna (Morocco):A-D, holotype ULB-IV-A(1a);A, dorsal view (digitally cut out of the matrix); B, frontal view; C, right lateral view; D, posterior view;E-H, paratype ULB-IV-A(1b); E, dorsal view; F, frontal view; G, posterior view;H, right lateral view; I, J, paratype ULB-IV-A(1c); I, dorsal view; J, frontal view. Arrows indicate the two anterolateral teeth distinctive of the species. Scale bar: 10 mm.

FIG. 4. — A, Braggicarpilius marginatus Beschin, Busulini & Tessier, 2015, holotype MCZ 3998, from the Ypresian (early Eocene) of Vestenanova (NE Italy) (digitally cut out of the matrix); B, Carpilius petreus Beschin, Busulini, De Angeli & Tessier, 2007, holotype MCZ 1809, from the Ypresian of Contrada Gecchelina (NE Italy) (digitally cut out of the matrix); C, D, Eocarpilius ortegai Artal & Van Bakel, 2018, topotype MGSB 77906a, from the Ilerdian (earlyYpresian) of Isábena (N Spain); C, frontal view; D, dorsal view; E, F, Oscacarpilius rotundus Artal & Van Bakel, 2018, from the Ilerdian of Isábena (N Spain); E, topotype MGSB 77905b; F, topotype MGSB 77905a. Scale bars: A, 5 mm; B-F, 10 mm.