The genusErymaMeyer, 1840 (Crustacea: Decapoda: Erymidae): new synonyms, systematic and stratigraphic implications

Abstract

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.

Review of the Late Jurassic erymoid lobsters (Crustacea: Decapoda)

“…The age of this species is Callovian (Middle Jurassic). Devillez & Charbonnier (2019) have redescribed it in the review of the Early and Middle Jurassic erymids, so it will not be discussed here.…”

“…With 36 species reported, the Late Jurassic erymoid fauna is the most diversified. Indeed, it is more than the number of species reported in Early and Middle Jurassic together (Devillez & Charbonnier 2019) or in Cretaceous (Devillez et al 2016(Devillez et al , 2017. So, this period is of high interest in the evolutionary history of these lobsters.…”

“…Following the recent studies of Devillez et al (2016Devillez et al ( , 2017 and Devillez & Charbonnier (2017), the present contribution aims to give a new look at the Late Jurassic erymoid species, which benefit of new descriptions.…”

New erymid lobsters from the Nusplingen and Usseltal formations (Upper Jurassic) of southwest Germany

“…More complete specimens, with the carapace and corresponding chelae preserved, are only found when conditions were favourable or within concretions (e.g., Hyžný et al, 2015). At generic level, erymid lobsters are distinguished mainly by their characteristic carapace groove pattern (Devillez & Charbonnier, 2017, 2020Devillez et al, 2018), while chela shape is less characteristic, at least in Eryma s. str. In the latter, there is one clade that has chelae with relatively short fingers; this group is distinguished from another with strikingly longer, straight fingers, although the groove pattern of the carapace is the same.…”

“…As a result, some species of Eryma of the second clade, previously included in a distinct genus, Erymastacus Beurlen, 1928(see Hyžný et al, 2015, have later been considered to belong to Eryma s. str. (Devillez & Charbonnier, 2017, 2020. However, there are further taxa that have long and curved fingers, but a different groove pattern on their carapace.…”