Pseudastacus Oppel, 1861

Charbonnier, Sylvain & Audo, Denis, 2020, A new stenochirid lobster (Crustacea, Decapoda, Stenochiridae) from the Early Jurassic of France, Geodiversitas 42 (7), pp. 93-102 : 95-96

Genus Pseudastacus Oppel, 1861

Pseudastacus Oppel, 1861b: 360 .

TYPE SPECIES. — Bolina pustulosa Münster, 1839, by subsequent designation of Glaessner (1929: 350).

INCLUDED SPECIES. — Schweitzer et al. (2010) listed five species included in Pseudastacus : P. hakelensis Fraas, 1878 (Cenomanian, Lebanon), P. minor Fraas, 1878 (Cenomanian, Lebanon), P. mucronatus ( Phillips, 1835) (Hauterivian, United Kingdom), P. pusillus Van Straelen, 1925 (Bajocian, France), and P. pustulosus ( Münster, 1839) (Tithonian, Germany). TAXONOMIC COMMENTS

Pseudastacus hakelensis was moved to Notahomarus by Charbonnier et al. (2017). The type material of Pseudastacus minor is lost (G. Schweigert pers. comm. 2019) and the illustration proposed by Fraas (1878: pl. 4, fig. 2) is not conclusive concerning the taxonomic determination. Indeed, his illustration is relatively strange for the following reasons: 1) either there is a wrong number of pleonal somites (7 instead of 6 excluding the telson), or the first somite is rather large; 2) the rostrum is exceedingly long in comparison with the rest of the carapace; and 3) as the carapace and pleon seem to be in connection suggesting that the specimen was a corpse, the first chelipeds appear strangely placed and should be positioned more anteriorly; in addition, the general morphology of the chelae does not fit with that observed in Pseudascatus.

The type material of Pseudastacus pusillus was destroyed during World War II (see Bigot 1945) and the figure proposed by Van Straelen (1925: pl. 9, fig. 7) is not conclusive. Even if the line drawing provided by Van Straelen (1925: fig. 134) shows the carapace groove pattern, it is difficult to confirm the assignation to Pseudastacus , which was already proposed with a question mark in the original publication.

The type material of Pseudastacus mucronatus corresponds to a fragment of P1 chela figured by Phillips (1829: pl.3, fig. 3) and Phillips (1835: pl. 3, fig. 3), and refigured by Bell (1863: pl. 9, fig. 6). This isolated chela is very massive and the occlusal margins of index and dactylus show very strong tubercles alternating with smallest ones. This general morphology is not consistent with the more elongate and thinner P1 chelae observed in Pseudascatus. Following Woods (1931: 89), this P1 chela might be referred to Hoploparia dentata (Roemer, 1841).