Paradoris lopezi, Hermosillo & Valdes, 2004

Dayrat, Benoît, 2006, A taxonomic revision of Paradoris sea slugs (Mollusca, Gastropoda, Nudibranchia, Doridina), Zoological Journal of the Linnean Society 147 (2), pp. 125-238 : 195-197

PARADORIS LOPEZI ( FIG. 52 )

Paradoris lopezi Hermosillo & Valdés, 2004: 551–556 , figs 1A, B, 2, 3.

Type material: Holotype, by original designation: Mexico, Baja California Sur, La Paz, Punta de Pichilingue, 24°21.25′N, 105°33.88′W [note that the original description provides the erroneous longitude of 110°17′W], 1 m depth, 31 October 2004, one specimen 32/ 22 mm, leg. A. Hermosillo ( CASIZ 171661 ). One paratype: Mexico, Jalisco-Nayarit, Bahía de Banderas , Majahuitas, 20°29.111′N, 105°35.057′W, 12 m depth, 10 March 2004, one specimen 27 mm in length ( LACM 3041 ). The holotype, deposited at the CAS, could be reexamined. The paratype, however, requested in January 2005 from Dr Valdés, Los Angeles County Museum of Natural History , was never received. The holotype had been opened dorsally and the reproductive system pulled out from the body cavity before the present study. Here I add drawings of the reproductive system of the holotype (the original description was largely based on the paratype).

Distribution: So far, lopezi is only known from two specimens collected from the Pacific coasts of Mexico.

Remarks on the original description ( Fig. 52 ): According to Hermosillo & Valdés (2004), the preserved holotype measured 22/ 12 mm. However, I found that it measured 32/ 22 mm. The background colour of the dorsal notum is grey, mainly due to pigmentation around the wide holes ( Fig. 52B ), and the tubercles are yellowish. The authors counted seven branchial plumes and 15 rhinophoral lamellae: I could not count them. The dorsal notum is covered by tall indecora -like tubercles ( Fig. 52A ), the ones in the median part of the notum being larger. Contrary to what the original description indicates, the oral tentacles are distinctly grooved ( Fig. 52C ). The stomach is free. According to the original description, the labial cuticle of lopezi only has one pair of lateral jaw plates. It is very probable that the third, median jaw plate was overlooked by the authors. According to the authors, the radular formula was 23 × (17-0-17): the number of rows is remarkably small compared with what is known in Paradoris , and it is probable that future specimens will have significantly longer radulae. The description of the reproductive system provided in the original description differs from what I could observe in the holotype. The deferent duct of the holotype had fewer loops than the paratype ( Hermosillo & Valdés, 2004; fig. 3A). The authors mentioned an ‘extremely narrow’ deferent duct: the deferent duct certainly is narrow, as in the vast majority of discodorids, but not ‘extremely narrow’ ( Fig. 52D ). The authors mentioned an unarmed penis. I did not find any penis in the reproductive system of the holotype, and it is probable that the authors called ‘penis’ what might just have been an evaginable papilla, simply part of the distal deferent duct. More importantly, the authors found just one stylet sac and two accessory glands in the distal part of the reproductive system of the paratype. I actually found three stylet sacs and two accessory glands ( Fig. 52D, F ). One sac was easily observable, on the external side of the reproductive system. Two additional stylet sacs ( Fig. 52F ) were embedded within some tissue between the deferent, vaginal, and female ducts, and could only be seen by taking apart the distal region of the reproductive system.

Discussion: This species clearly belongs to Paradoris , but not for the reasons given by Hermosillo & Valdés (2004). Indeed, none of the ‘features characteristic of the genus Paradoris ’ that they listed are synapomorphies of Paradoris . However, based on my reexamination of the holotype (grooved oral tentacles, wide holes in the notum) and the original description (lateral groove of the radular teeth), lopezi does present the synapomorphies of Paradoris . I could not verify whether lopezi has three jaw plates (instead of two, as described by Hermosillo & Valdés), and whether it has an elongated radula (the number of rows provided by Hermosillo & Valdés is suspicious).

Hermosillo & Valdés compared lopezi with four existing species: leuca , then known from New Zealand and regarded here as a synonym of dubia ; tsurugensis , from Japan; araneosa and imperfecta , both names being regarded as synonyms here, from deep waters off New Caledonia. One of the main arguments of the authors for distinguishing lopezi from these species is the fact that lopezi supposedly has two accessory glands and one stylet sac in the distal part of the reproductive system. The fact that I found three stylets instead of one in the holotype invalidates the comparisons provided by Hermosillo & Valdés. The problem is that I could not verify the number of accessory glands and sacs in the paratype (I requested it but I never received it). Therefore, it is not possible for me to say whether the paratype had a different number of glands and sacs than the holotype (which would definitely be possible given that this number does vary infra-specifically), or if Hermosillo & Valdés also overlooked two stylets in the holotype. In any case, lopezi differs from dubia , with which it does not share the diagnostic reproductive feature (the fused fertilization and vaginal ducts near the bursa copulatrix); and the colour of lopezi differs from that of araneosa . The comparison with tsurugensis , poorly known, is highly problematic: the number of radular rows mentioned by Hermosillo & Valdés might be less clear-cut because they might have underestimated the number of rows in the paratype of lopezi .

More importantly, Hermosillo & Valdés overlooked the existence of mulciber , known from Brazil and Costa Rica. The main problem is that our knowledge of the anatomy and external morphology of mulciber is quite limited: the colour of the live animal is unknown; it has three stylet sacs (but only two specimens were dissected) and an unknown number of accessory glands.

In summary, our knowledge of lopezi is problematic for several reasons: only two specimens have been dissected and we have no knowledge of individual variation (especially for coloration); the anatomy of the holotype, re-examined for the present study, contradicts the original description for several important features, such as the grooved oral tentacles and the number of accessory glands and stylet sacs in the distal part of the reproductive system. Finally, comparisons with other species, such as tsurugensis and, more importantly, mulciber , are jeopardized by the fact that those species are also very poorly known. However, an interesting and potentially useful character for distinguishing lopezi from the rest of the species is the presence of dark red tubercles on the dorsal notum. However, this will need to be studied in more specimens, as well as in other species. Here I regard lopezi as a valid species name, but that refers to a very insufficiently known taxon. Whether it is a distinct taxon will have to be addressed more thoroughly when additional specimens are available (for lopezi as well as for other species with which it will need to be compared).

Figures

Figure 52. Paradoris lopezi, holotype, CASIZ 171661. A, dorsal mantle tubercles, scale = 2.3 mm. B, wide mantle holes, scale = 0.3 mm. C, anterior foot, with grooved oral tentacles, scale = 1.2 mm. D, reproductive system (external view, no dissection), scale = 1 mm. E, spermatic pouches and ducts (dissected), scale = 0.8 mm. F, distal part of the reproductive system (dissected), scale = 0.3 mm.