Proeryon, a geographically and stratigraphically widespread genus of polychelidan lobsters

Polychelidan lobsters are decapod crustaceans characterized by their four to five pairs of claws. The first description of a polychelidan lobster dates back to 1817, and since then, numerous species have been described with varying level of details. This situation sometimes led to the description of synonymous species, and more generally, led to a lack of overview on the group systematic and evolutionary history. Herein, we review Proeryon¸ one of the most diversified and stratigraphically widespread polychelidan. We argue that Proeryon is closely allied to Tethyseryon and Gabaleryon and propose to assign them to Proeryoninae nov. subfam., which are mainly characterized by their hemicircular ocular incision, postorbital and branchial carinae not joined together, and axial carina on pleonites cut by transverse grooves. Proeryon is in turn characterized by its marked cervical and hepatic incisions, simple posterolateral spines and arched uropodal exopod diaeresis. Thus defined, we assign the following species to Proeryon: P. charbonnieri, P. giganteus, P. hauffi, P. laticaudatus, P. richardsoni, P. stoddarti and two unnamed species from the Hauterivian of Germany and Switzerland, respectively. In addition, we refer to Proeryon, with some reservations, two new species,?Proeryon quiltyi from the Callovian of Antarctica and?Proeryon erinaceus from the Oxfordian of France. Proeryon has highly discontinuous but large stratigraphic (Pliensbachian - Hauterivian: about 60 MA) and palaeogeographic (from United Kingdom to Siberia, and to Antarctica) distribution. Most of these species occurs in relatively deep neritic or deeper palaeoenvironments. It is possible that this deep-sea dwelling is one of the reasons why Proeryon survived so long. Also, we note the presence of abundant oysters living as epibionts on some specimens of Proeryon hartmanni. Their disposition and number suggest that P. hartmanni was an epibenthic animal.