Pleurobranchus iouspi, Ev. Marcus, 1984

Grzelak, Katarzyna & Sørensen, Martin V., 2022, Echinoderes galadrielae Grzelak & amp; Sørensen 2022, sp. nov., Zoological studies 55 (15), pp. 1-31 : 27-28

Pleurobranchus iouspi and P. testudinarius are distinct species

Pleurobranchus iouspi is currently considered a potential synonym of P. testudinarius ( Goodheart et al. 2015) . The configuration of the penial flaps is similar in both P. testudinarius and P. iouspi , however, they are not identical. According to the original description and illustrations and the redescription in the present study of P. iouspi and the specimen from Maranhão state (Ev. Marcus 1970), the genital aperture, including the penis, is surrounded by three distinct large penial flaps ( Figs. 12 A-C). In contrast, P. testudinarius has several penial flaps laterally and ventrally to the penis in P. testudinarius ( Martynov and Schrödl 2009: 60, fig. 5A; this study, P. testudinarius from Bay of Naples, Italy [1]: MV F85659). Therefore, the penial flaps do not surround the penis in P. testudinarius as is the case in P. iouspi ( Figs. 12 A-B), which leads us to believe that the specimen from Maranhão state (Ev. Marcus 1970) actually corresponds to P. iouspi .

Pleurobranchus iouspi Ev. Marcus, 1984 was described based on a single specimen from the coast of São Paulo state, and only recorded as “ Oscanius (?) testudinarius ” based on specimen from Maranhão state. Recently collected specimens and the rediscovery of the slides of the holotype in the MZSP allowed us to re-describe this species. The distinguishing features mentioned in the original description, which allowed the determination of the specimens in this study are: the size of the tubercles on the mantle, genital apertures surrounded by three large flaps ( Figs. 12 A-C), deferent duct spiraling into the smooth muscular conical penis, the non-contractile penis ( Figs. 11 F-H; 12F), and the asymmetrical basal penial lobe ( Figs. 11G ; 12 B-C, E-F). Goodheart et al. (2015) analyzed only nuclear data (histone 3, H3) of specimens from Brazil and Mediterranean Sea and suggest that P. iouspi and P. testudinarius are possibly synonyms. We believe that it is better to keep P. testudinarius and P. iouspi as distinct due the fact that the nuclear data alone of few specimens is not a strong evidence of conspecificity because it is a conservative data, the fragment studied by Goodheart et al. (2015) is very short resulting in a limited data problem, and mostly due the diagnostic differences in the flaps on the gonopore. The detailed anatomical study provided in the present paper permit that future studies compare anatomically this description with material from Mediterranean Sea.

Figures

Fig. 12. Pleurobranchus iouspi Ev. Marcus (1984). (A) lateral view, detail near gill (MNRJ 33070). (B-C) detail of gonopore. (B) view from the top (MNRJ 33069). (C) lateral view (SAE ML 95). (D-E) reproductive system deflected; (D) (MNRJ 33070). (E) (MNRJ 33069). (F) penis dissected longitudinally (SAE ML 95). (G) nervous system (SAE ML 95). Abbreviations: a, anus; am, ampulla; bc, buccal ganglion; bu, bursa copulatrix; ccpb, connective between buccal and cerebro-pleural ganglia; cp, nerves that leave from the cerebro-pleural ganglion; cpg, cerebro-pleural ganglion; cpp, commissure between the pedal ganglia; dd, deferent duct; e, eye; f, female opening; fg, female gland; gi, gill; go, gonopore; gm, gill membrane; nb, nerves that leave from the buccal ganglion; np, nerves that leave from the pedal ganglion; ov, oviduct; p, penial papilla; pb, prebranchial aperture; pf, penial flap; pg, pedal ganglion; pr, prostate; rg, rhinophoral ganglion; rh, rhinophore; rn, rhinophoral nerve; sr, seminal receptacle; tu, tubercles; va, vagina.

Fig. 11. Microscopic slides of the holotype of Pleurobranchus iouspi Ev. Marcus, 1984 (MZSP 119936); for discussion about slides’s label, see text. (A) radula. (B) jaw platelets. (C) portions of the mantle. (D) unrecognizable parts of reproductive system. (E) penis. (F-H) details of the penis. Abbreviations: bb, basal bulb; dd, deferent duct; p, penial papilla; pe, penis; pr, prostate.