Paracratis borealis (Jeffreys, 1869)

Simone, Luiz Ricardo L., 2024, New species, misidentifications and problematic taxonomy of some Atlantic South American marine mollusks: a review, Papéis Avulsos de Zoologia 64, pp. 1-104 : 73

Paracratis borealis (Jeffreys, 1869) revalidated, new combination ( Fig. 48F )

Limopsis borealis Jeffreys, 1869: 174-175 .

Limopsis minuta : Maury, 1920: 43; Poirier, 1954: 148; Rios, 1975: 195 (pl. 62, fig. 952), 1985: 211 (pl. 76 fig. 1075), 1994: 233 (pl. 81, fig. 1152), 2009: 478 (fig. 1345); Gofas et al., 2001: 206; Janssen & Krylova, 2014: 56; Janssen, 2015: 16, 25; Molluscabase, 2024; Passos et al., 2024: 28 (non Philippi, 1836).

Type localities: 50 miles N of Hebrides, 189 fms. E Nordland, 70-100 fms. Upper Norway, 450 fms.

Remarks: Paracratis borealis ( Fig. 48F ) has previously been identified as Limopsis minuta , described by Philippi as Pectunculus minutus in 1836 (pg. 63, pl. 5, fig. 3) ( Fig. 48E ). This species was initially described from the Plio-Pleistocene deposits in Sicily, Italy (Mediterranean). It has been reported as present in the Recent period from Canada to Mexico, with some disjunct occurrences in South Brazil (e.g., Rios, 2009).

Despite the significant temporal and regional differences, which might suggest a strong case for specific separation, Limopsis minuta , as described and illustrat- ed by Philippi (1836), still exhibits conchological distinctions ( Fig. 48E ). It is notably larger, reaching around 15 mm, whereas P. borealis measures approximately 6 mm. Furthermore, Limopsis minuta features a more arched hinge and a taller umbo compared to those of P. borealis ( Fig. 48F ). The shell outline is also much less inclined (around 80°), while P. borealis has an angulation of approximately 65°.

Based on these temporal, geographic, and morphological differences, the most appropriate taxonomical procedure is to maintain Limopsis minuta as a Plio-Pleistocene Italian fossil within the genus Paracratis . Concurrently, its previous synonym, P.borealis , should be revalidated to represent the Recent Atlantic species.

Figures

Figure 48.Reported species of Limopsidae:(A) replica of Arcaaurita Brocchi,1881 original image (pl.11, sp.9), aPliocene Italian fossil;(B-D) L.paucidentata MZSP 156267 (W 10.4 mm);(B) fully left view; (C) right valve,inner view;(D) left valve containing soft parts, right view;(E) replica of Pectunculus minutus Philippi,1836 original image (pl. 5,fig.3),a Plio-PleistoceneItalian fossil;(F) Paracratisborealis from Josephine seamount (W 6.7 mm) (by Gofas Serge,MolluscaBase,reproduced under permission),left valve,outer view,and rightvalve,inner view.