Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)

Abstract

The Late Jurassic marks the first major radiation among true crabs (Brachyura) in reef environments, followed by another diversification in the mid-to Late Cretaceous in multiple habitats. We studied brachyuran carapaces from Mesozoic sponge-and coralassociated limestones in Europe. Six new taxa are described: Late Jurassic Europrosopon gen. nov., Eodromites bernchrisdomiorum sp. nov., Prosopon josephcollinsi sp. nov., Tanidromites nightwishorum sp. nov., and T. weinschenki sp. nov.; and mid-Cretaceous Eodromites cristinarobinsae sp. nov. Furthermore, we recognize four junior synonyms: Eodromites grandis (=E. guenteri), Tanidromites scheffnerae (=T. wysokaensis), and Europrosopon aculeatum (=E. verrucosum and E. barbulescuae). Five taxa are reassigned: Eodromites aequilatus to Tanidromites, Tanidromites rotundus to Eodromites, Nodoprosopon dzhafarberdensis to ?Abyssophthalmus, Nodoprosopon from Nodoprosopidae to Homolodromiidae, and Rathbunopon from Glaessneropsidae to Prosopidae. Several other taxa are redescribed. The latter reassignment indicates that Rathbunopon does not represent an example of extreme convergent evolution as implied previously. Conversely, the frontal structure consisting of a rostrum with two diverging spines and outer orbital spines appears a remarkable example of convergent evolution of the goniodromitid Navarradromites toward members of Homolodromiidae, for which this frontal structure is characteristic. Rostral spines represent another example of convergent evolution. Some specimens are extraordinary: A specimen of Abyssophthalmus cf. A. spinosus represents the largest complete reported Jurassic brachyuran thus far and one specimen of Planoprosopon aff. P. hystricosus bears one of the largest known parasitic isopod-induced swellings (ichnotaxon Kanthyloma crusta) relative to carapace size. Overall, our results indicate that biodiversity and convergent evolution in Mesozoic brachyurans remain understudied.

Bajoprosopon piardi n. gen. and sp. from the Middle Jurassic of France, with a revised diagnosis of the family Prosopidae von Meyer, 1860 (Brachyura, Podotremata) and notes on the availability of names introduced by Hermann von Meyer (1835, 1857)

“…Order DECAPODA Latreille, 1802 Infraorder BRACHYURA Linnaeus, 1758 Section PODOTREMATA Guinot, 1977Subsection DYNOMENIFORMIA Guinot, Tavares, and Castro, 2013Superfamily HOMOLODROMIOIDEA Alcock, 1900 Family PROSOPIDAE von Meyer, 1860 Included genera (see Figure 3). Klompmaker et al (2020). These authors also argued that the orbital construction in Prosopon, Europrosopon, and Rathbunopon was less unique than previously thought by Schweitzer et al (2012Schweitzer et al ( , 2018; we concur.…”

“…The stratigraphical range of the family is Middle Jurassic (Bajocian: Bajoprosopon piardi n. gen.and sp. and Prosopon mammillatum Woodward, 1868) to mid-Cretaceous (Cenomanian: Rathbunopon woodsi Withers, 1951 and R. polyakron [Stenzel, 1945]), with numerous Jurassic members having been recorded from sponge-coral reef environments (Schweitzer and Feldmann, 2009;Klompmaker et al, 2020) (see also Table 1). Morphologically, the new genus appears closest to Prosopon, based on the weak branchial condensation, i.e., the clear separation of branchial and cervical grooves, considered to be a basal condition.…”

“…In many recent papers dealing with prosopid crabs, the date for these species has been erroneously noted as 1857. For instance, Klompmaker et al (2020) have recently considered Prosopon verrucosum Reuss, 1858 to be a junior synonym of Prosopon aculeatum von Meyer, 1857. However, the specific epithet aculeatum did not become available until 1860, and should thus be considered a junior synonym of verrucosum, instead vice versa.…”

“…However, the specific epithet aculeatum did not become available until 1860, and should thus be considered a junior synonym of verrucosum, instead vice versa. Klompmaker et al (2020) have also erected a new genus, Europrosopon Klompmaker, Starzyk, Schweigert and Fraaije, 2020, indicating (p. 21) the type species to be "Prosopon aculeatum von Meyer, 1857 (=Prosopon verrucosum Reuss, 1858)". ICZN Article 67.1.2 states that "The name of a type species remains unchanged even when it is a junior synonym or homonym".…”

A new subfamily classification of the highly diversified Dorippidae H. Milne Edwards, 1837 (Crustacea, Decapoda, Brachyura, Dorippoidea), using morphological, molecular and palaeotonlogical data, with special emphasis on its unique female reproductive system

“…Depending on the authors and groups considered (and even more so if podotreme crabs are included), it appears that the interpretation of the cervical groove in relation to the gastric pits is highly variable, with the gastric pits (also called ‘cervical pits’) being positioned either behind the cervical groove or on the cervical groove itself, leading to confusions (Klompmaker et al 2019, 2020). Numerous surveys have been conducted on the carapace and its grooves in Decapoda by neontologists (Boas 1880; Huxley 1877; Bouvier 1896; Pearson 1908; Renaud 1977) and many palaeontologists (e.g.…”