Erymoid lobsters (Crustacea, Decapoda, Erymoidea) are an important component of Mesozoic crustacean faunas in Europe, especially during the Jurassic. With 36 species reported, these lobsters reach their highest diversity during the Late Jurassic. After the review presented here, 23 species belonging to Eryma Meyer, 1840 (11 species), Palaeastacus Bell, 1850 (2 species), Pustulina Quenstedt, 1857 (2 species) and Stenodactylina Beurlen, 1928 (8 species) remain valid. One new species is described: Stenodactylina shotoverigiganti n. sp., and Eryma pseudoventrosa Beurlen, 1928 is integrated to Stenodactylina. We also notice the oldest representative of Enoploclytia M'Coy, 1849, known by a single specimen unidentified at specific level. Eryma ventrosum (Meyer, 1835) is the most common species in Western Europe, and may be seen as emblematic of the Middle-Late Jurassic. Moreover, the lithographic limestones of Germany yield an exceptionally diversified erymoid fauna, with four genera (Eryma, Palaeastacus, Pustulina, Stenodactylina) and 11 species listed. All the Late Jurassic representatives of Palaeastacus were found in this lithology. Finally, the examination of some specimens allows the observation of the strong effects of the decortication on the ornamentation of the erymoids and the resulting taxonomic issues.
Erymid lobsters (Crustacea, Decapoda, Erymidae) are an important component of Mesozoic crustacean faunas in Europe, especially during the Jurassic. The 29 species reported from the Early and Middle Jurassic are the oldest found in Western Europe and North America, and constitute an important part of the evolutionary history of these lobsters. After the review presented here, 24 species are maintained within the genera Eryma Meyer, 1840 (7 species), Palaeastacus Bell, 1850 (5 species), Pustulina Quenstedt, 1858 (2 species) and Stenodactylina Beurlen, 1928 (9 species). All these species, with the exception of Eryma ventrosum (Meyer, 1835), have a new description and the diagnoses of the genera Eryma, Palaeastacus and Stenodactylina are emended. Four species are transferred to another genus: Palaeastacus numismalis (Oppel, 1862) n. comb., Palaeastacus foersteri (Feldmann, 1979) n. comb. and Stenodactylina guisei (Wright, 1881) were previously assigned to Eryma, and Stenodactylina spinosa (Étallon, 1861) n. comb. was previously assigned to Palaeastacus. Our study shows that Stenodactylina was the most diversified genus in Early – Middle Jurassic, but the fossils of Eryma are more common. Furthermore, Eryma compressum (Eudes-Deslongchamps, 1842) is the emblematic species of Erymidae Van Straelen, 1925 during the end of Early Jurassic and Middle Jurassic in Western Europe (Toarcian – Bathonian). This species includes now Eryma bedeltum (Quenstedt, 1858) in its synonymy. The genus Pustulina is very rare and the specimens show some characteristics on their carapace recalling other erymid genera (an almost sinuous hepatic groove for example), that are absent in more recent species. Finally, we point out that only E. compressum, P. foersteri and Stenodactylina walkerae (Feldmann and Haggart, 2008) are reported outside Europe.
Among Erymidae Van Straelen, 1925 (Van Straelen V. 1925. Contribution à l'étude des crustacés décapodes de la période jurassique. Mémoires de la Classe des Sciences de l'Académie royale de Belgique 7: 1–462), typical Mesozoic crustaceans, the genus Eryma Meyer, 1840 (Meyer H. von. 1840a. Briefliche Mittheilungen. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefactenkunde 576–587) includes the largest number of species, mainly from Jurassic deposits. However, the lack of clear diagnoses for erymid genera has led to mistakes in generic assignments and to the establishment of redundant genera. The review of the concept of Eryma herein presents an attempt to clarify its diagnosis, mainly supported by the carapace groove pattern and the morphology of chelae of the first pair of pereiopods, and to emphasize its systematic implications. Thus, we maintain the synonymy of Klytia Meyer, 1840, Bolina Münster, 1839 (Münster G. 1839. Decapoda Macrura. Abbildung und Beschreibung der Fossilen Langschwänzigen Krebse in den Kalkschiefern von Bayern. Beiträge zur Petrefaktenkunde 2: 1–88) (sensu Étallon [Étallon A. 1859. Description des crustacés fossiles de la Haute-Saône et du Haut-Jura. Bulletin de la Société géologique de France 16: 169–205]), and Erymastacus Beurlen, 1928 (Beurlen K. 1928. Die Decapoden des Schwäbischen Jura mit Ausnahme der aus den oberjurassischen Plattenkalken stammenden. Palaeontographica 70: 115–278) with Eryma. Moreover, a review of the genera Protoclytiopsis Birshtein, 1958 (Birshtein JA. 1958. Ein Vertreter der ältesten Ordo der Crustacea Decapoda Protoclitiopsis antiqua gen. nov. sp. nov. aus dem Permo West-Sibiriens. Doklady Akademii Nauk, SSSR 122: 477–480), and Galicia Garassino and Krobicki, 2002 (Garassino A, Krobicki M. 2002. Galicia marianae n. gen., n. sp. (Crustacea, Decapoda, Astacidea) from the Oxfordian (Upper Jurassic) of the Southern Polish Uplands. Bulletin of the Mizunami Fossil Museum 29: 51–59), reveals the presence of a junction between the postcervical and branchiocardiac grooves. This feature is diagnostic of Eryma and supports the integration of these genera into the synonymy of Eryma. The addition of Protoclytiopsis to the synonymy of Eryma makes Eryma antiquum (Birshtein, 1958) nov. comb. the oldest representative of the genus and of the family, extending its stratigraphic range to the Late Permian (Changhsingian). Thus, this work also emphasizes that Erymidae crossed the Permian-Triassic boundary.
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