Hepatus beurleni

Lima, Daniel, Silva, Rafael Costa da, Aguilera, Orangel, Pinheiro, Allysson Pontes & Santana, William, 2023, Brazilian Miocene crabs I. Taxonomic review of Cyclocancer tuberculatus Beurlen, 1958 and Hepatella amazonica Beurlen, 1958 (Pancrustacea, Decapoda, Brachyura), Papéis Avulsos de Zoologia 63, pp. 1-9 : 3-4

Hepatus beurleni nomen nov.

( Fig. 2 A-E) https://zoobank.org/ 78AF63CA-91E9-499D-B3E8-ED1BE02E7A26

Cyclocancer tuberculatus Beurlen, 1958: 15 [type locality: Pirabas Formation, Brazil, Pará holotype (MNRJ-4617-I). – Schweitzer et al., 2010: 102; Távora et al., 2010b: 214; Luque et al., 2017: 12.

Type material: Holotype MNRJ-4617-I, part and counterpart, early-middle Miocene, Pirabas Formation, Brazil, Pará, Ilha de Fortaleza , Ponta da Fazenda, C.S. Ferreira e O. R. da Cunha coll.

Occurrence and age: Brazil, Pará,Ilha de Fortaleza,Ponta da Fazenda, Pirabas Formation, early-middle Miocene.

Etymology: The specific epithet of the new name honors Karl Beurlen, a prominent German paleontologist who worked in the Instituto Geológico Brasileiro and described this species.

Diagnose: Carapace ovoid, wider than long (cw 38 mm, cl 28 mm; W/L ratio 1.4). Rostrum narrow, orbits small. Anterior margins convex, strongly crenated, lobes extending to anterior posterolateral margins.Posterolateral margins short, slightly concave, upturned anteriorly, crenulated posteriorly, with a large knob-like lobe separating it from the posterior margin. Posterior margin narrow, straight, crenulated. Greatest width near midlength. Carapace with 8 protuberances on gastric, cardiac, and branchial regions; mesogastric region higher than the remaining carapace regions; protuberances surmounted with a cluster of small granules. Mesobranchial protuberance oblong, transversal separated from gastric and cardiac regions by a shallow groove.

Remarks: Cyclocancer tuberculatus Beurlen,1958 is herein transferred into Hepatus as H. beurleni nomen nov., a new species name for H. tuberculatus ( Beurlen, 1958) as it became a junior homonym of H. tuberculatus Saussure (1858) , a junior synonym of Hepatus pudibundus (Herbst, 1785) .

Janssen & Müller (1984) were the first to indicate that Cyclocancer tuberculatus is more related to Hepatus than to any other Cancroidea (superfamily where Cyclocancer Beurlen, 1958 was originally included). Salva & Feldmann (2001) also questioned the position of Cyclocancer in Cancridae , although not citing its resemblance with Hepatus . Feldmann et al. (2005) mentioned that when the front of the carapace is missing, as is the case of the holotype of Hepatus beurleni nomen nov., it is difficult to distinguish Hepatus from the cancrid Metacarcinus A. Milne-Edwards, 1862 ; however, the presence of distinct elevations of the carapace in Hepatus makes possible to differentiate it from Metacarcinus .

Hepatus beurleni nomen nov., has the diagnostic characters of Hepatus (as understood by Feldmann et al., 2005: 433), such as carapace much broader than long, broadly obovate, vaulted; crenated anterolateral margins; posterolateral margin concave; and posterior margin narrow.

Among the fossil species, H. lineatinus and H. biformis from the late Pliocene of Panama and Miocene- Pliocene of Panama and Costa Rica, respectively, differ from H. beurleni nomen nov. (characters within brackets) by having the carapace anterolateral margins tridenticulate (vs anterolateral margins with short lobes of about the same size). Hepatus guraboensis Collins , in Collins et al., 2009, from the Miocene of the Dominican Republic stands apart by having the anterolateral margins with short triangular spines increasing in size posteriorly (vs anterolateral margins strongly crenated). Hepatus nodosus Collins & Morris, 1976 , from the Miocene of Trinidad differs by having the anterolateral margins divided into four blunt teeth (vs anterolateral margins strongly crenated, extending to anterior posterolateral margins). Hepatus bottomsi Blow, 2003 , from the Pliocene of Virginia, United States, can be distinguished by the anterolateral margins of the carapace consisting of 40 blunt denticles situated from 12-13 or more bidentate or tridentate teeth (vs anterolateral margins consisting of simple lobes). Hepatus pauli Collins, Garvie & Mellish, 2014 , from the Pleistocene of Texas, United States, differs by having 12-13 tridentate spines on the anterolateral margins (vs anterolateral margins consisting of simple lobes). Hepatus spinimarginatus Feldmann, Schweitzer & Encinas, 2005 , from the Miocene of Chile differs by having the posterolateral margins rimmed by very finely beaded elevation (vs posterolateral margin strongly crenulated).

The following set of characters differentiate H. beurleni nomen nov., from all of its extant congeners: 1) posterior margin narrow, crenulated, almost straight; 2) posterolateral margin strongly crenulated with a large lobe between the posterolateral and posterior margins; and 3) anterolateral margin crenated, with short lobes of about the same size.

The holotype MNRJ-4617-I had been missing for decades and was considered lost, but was recently found together in the MCTer collection, probably due to an old forgotten loan, posteriorly returned to the institution of origin (Museu Nacional do Rio de Janeiro /MNRJ). This fact allowed the specimen to escape the fire that hit the Museu Nacional in 2018 and destroyed a large part of the paleontological collections, which gives it even greater importance.