Eoparanaxia eocenica, Ferratges & Domínguez & Ossó & Zamora, 2023

Ferratges, Fernando A., Domínguez, Josep Lluis, Ossó, Àlex & Zamora, Samuel, 2023, Spider crabs (Decapoda: Brachyura: Majoidea) from the upper Eocene of south Pyrenees (Huesca, Spain), Palaeontologia Electronica (a 27) 26 (2), pp. 1-29 : 11

Eoparanaxia eocenica n. sp.

Figures 3 and 4

zoobank.org/ 1AAD44D5-0D9C-4642-8FC2-85193465EFDF

Type material. Holotype ( MPZ 2023 /1), a near-complete carapace, partially decorticated . Paratypes ( MPZ 2023 /2 and MPZ 2023 /3) that correspond to one rostrum and half of a posterior carapace .

Diagnosis. As for the genus, by monotypy.

Description. Carapace pyriform, longer than wide, with spines and conical tubercles; pseudorostral spines parallel and fused, distally bifid, 0.53 times CW, with a row of aligned granules on each spine; orbits not well preserved, small, rounded, obliquely directed. Regions well defined by shallow grooves and deep branchiocardiac groove, with spaced and large spines at the top of the dorsal regions. Gastric region prominent, slightly higher than other regions, with pointed tubercles distributed in anterior gastric region, becoming long gastric spines on the axis of the carapace; urogastric region more depressed. Hepatic region slightly swollen, with one acute stout spine directed anterolaterally. Branchial regions inflated; epibranchial region inflated; mesobranchial region crossed by oblique ridge with five tubercles/spines. Cardiac region elevated, with two tubercles in the anterior part and one in the posterior margin. Intestinal tubercle large, protruding beyond posterior margin of carapace, conical, apex pointed.

Anterolateral margin slightly sinuous. Posterolateral margin convex, with a long spine laterally directed obliquely. Posterolateral and posterior margin rimmed.

Etymology. The specific name refers to the Eocene.

Remarks. Some species of the genus Paranaxia like P. keesingi Hosie and Hara, 2016 , and P. serpulifera (Guérin, 1832, in Guérin-Méneville 1829- 1837) show similarities with the material studied here. Nevertheless, these taxa have unfused pseudorostral spines, clearly divergent. The new taxon bears some similarities with Macrocheira longirostra Schweitzer and Feldmann, 1999 , with a similar outline of the carapace, bifid rostrum, very long pseudorostral spines fused at the base, and divergent at the tip. However, M. longirostra show some differences: 1) lacks spines at the posterolateral margins; 2) has a posterior margin almost straight without intestinal spine; and 3) a dorsal surface much more tuberculated than the new taxon.

Figures

FIGURE 3. Eoparanaxia eocenica n. gen. n. sp. A-C: Holotype MPZ 2023/1, from the Pamplona Marls Formation (upper Eocene, southern Pyrenees); D: posterior part of Eoparanaxia eocenica, paratype MPZ 2023/2; E-F: paratype MPZ 2023/3. A-C are from locality west Fanlillo (Figure 1) and D-F from locality east Fanlillo.

FIGURE 4. Idealized reconstruction of Eoparanaxia eocenica n. gen. n. sp. carapace.