Runcina divae, OR LAPINURA DIVAE

Araujo, Ana Karla, Pola, Marta, Malaquias, Manuel Antonio E, Ballesteros, Manuel, Vitale, Fabio & Cervera, Juan Lucas, 2022, Molecular phylogeny of European Runcinida (Gastropoda, Heterobranchia): the discover of an unexpected pool of complex species, with special reference to the case of Runcina coronata, Zoological Journal of the Linnean Society 194 (3), pp. 761-788 : 781

RUNCINA DIVAE OR LAPINURA DIVAE ?

The genus Lapinura (type species: Ildica divae Marcus & Marcus, 1963 ), introduced by Marcus & Marcus (1970) for specimens collected in Curaçao, Bonaire and Florida, is characterized by an external cupshaped larval shell. This genus was synonymized with Runcina by Clark (1984) after examining populations from Bermuda of supposed Lapinura divae in which some specimens lacked the external shell. Because of this ‘variability’, Clark disregarded the external shell and others characteristics that define the genus, emphasizing only the radular formula (N × 1.1.1) and the presence of gizzard plates – common for most runcinids – to assign Lapinura divae to the genus Runcina .

Representatives of the Caribbean species Lapinura/ Runcina divae from Bermuda branched off outside Clade F (the one with the type species of the genus Runcina ) with other runcinids in Clade H. Therefore, we suggest that the genus Lapinura should be reinstated as valid and at least applied for the Caribbean species described by Marcus & Marcus (1963). Moreover, we agree with Ortea et al. (2017) about a possible existence of more than one species being referred under the name Lapinura divae , due to the discrepancies (number of rows of the radula, presence/absence of the shell and number of crests of the gizzard plates) among specimens collected in the Caribbean Sea and Brazil ( Marcus & Marcus, 1963; Marcus & Marcus, 1970; Thompson, 1977; Clark, 1984).

WHAT ABOUT EUROPEAN RUNCINIDS?

Three genera have been referred in European waters: Runcina (31 species), Runcinella (one species) and Pseudoilbia (one species). We have studied specimens of Runcina and Pseudoilbia but, unfortunately, specimens of Runcinella condio Moro & Ortea, 2015, described from the Canary Islands, were not available for study.

Runcinida

Here we add a fourth genus to the European fauna, namely Runcinida . To date, the genus Runcinida was restricted to the western Pacific Ocean and included three species, R. elioti ( Baba, 1937) , R. valentinae and R. marisae . However, according to our results, a specimen identified as Runcinida sp. 1, collected in Cap Ferret, France (Atlantic coast), clustered together with R. marisae and R. valentinae (PP = 1, BS = 90). Externally, all species of Runcinida can be distinguished by their unique colour pattern, with a dark-brown notum, yellowish or orange edge of notum and foot, and gills arranged in a semicircle above the anus. Our specimen ( Runcinida sp. 1; Fig. 8 ) fits this colour pattern and arrangement of the gills, but differs from the other species in the genus by having small, black dots spread on the dorsal and ventral surfaces of the foot and several larger white spots on the notum ( Fig. 8 ). Runcinida elioti ( Baba, 1937) has fewer white spots too, but lacks small, black dots on the foot ( Baba, 1937). Runcinida marisae has small, black dots on the ventral surface of the foot but white dots are absent (Chernyshev, 1998). Finally, Runcinida valentinae lacks black and white dots, but has a triangular orange patch on the anterior part of the notum ( Chernyshev, 2006). The ABDG and bPTP recognized Runcinida sp. 1, R. marisae and R. valentinae as distinct species with COI uncorrected p -distances ranging between 6.5% to 16.6% ( Table 2).

Figures

Figure 8. Living animal of Runcinida sp. (MNCN 15.05/90670, 3 mm in length, Cap Ferret, north of France, Atlantic Ocean). Image courtesy of Marina Poddubetskaia.