VIERAEA Vol. 36 137-141 Santa Cruz de Tenerife, octubre 2008 ISSN 0210-945X First record of Atlanta selvagensis de Vera & Seapy, 2006 (Gastropoda: Pterotracheoidea) from the Cape Verde Archipelago, Northeast Atlantic Ocean ALEJANDRO DE VERA1, FÁTIMA HERNÁNDEZ1, Mª EUGENIA LEÓN1 & ROGER R. SEAPY2 1 Museo de Ciencias Naturales de Tenerife (TFMC). O.A.M.C., Ap. Correos 853. S/C de Tenerife. Canary Islands. Spain. e-mail: avera@museosdetenerife.org 2 Department of Biological Science, California State University. Fullerton, California 92834 U.S.A. e-mail: rseapy@fullerton.edu DE VERA , A., F. HERNÁNDEZ, M.E. LEÓN & R. R. SEAPY (2008). Primer registro de Atlanta selvagensis de Vera & Seapy, 2006 (Gastropoda: Pterotracheoidea) para el archipiélago de Cabo Verde (Atlántico nororiental). V IERAEA , 36: 137-141. RESUMEN: Atlanta selvagensis, molusco heterópodo recientemente descrito a partir de muy pocos ejemplares capturados en una muestra de profundidad en el archipiélago de Salvajes (De Vera & Seapy, 2006), se registra ahora para Cabo Verde. La presente cita amplía el rango de distribución atlántico de esta nueva especie al haberse recogido a una latitud más meridional. Palabras clave: molusco, gasterópodo, Pterotracheoidea, Atlanta, Cabo Verde. ABSTRACT: The heteropod Atlanta selvagensis is recorded for the first time from Cape Verde Archipelago. This species was recently described from a limited number of specimens collected from waters around the Selvagens Islands (de Vera & Seapy, 2006). The present record extends the distribution range of this new species. Key words: mollusc, gastropod, Pterotracheoidea, Atlanta, Cape Verde. INTRODUCTION Atlanta selvagensis (de Vera & Seapy, 2006) was recently described from eight specimens collected from three samples during Cruise TFMCBMSV/00 to the Selvagens Islands. Based on the limited number of specimens collected, A. selvagensis appears to be an uncommon planktonic species. Subsequently, the first author has examined more 138 than a hundred of plankton samples, collected from a dozen of cruises to the Macaronesian archipelagos, deposited at the Museum of Natural Sciences of Tenerife (TFMC). This work extends, for the present time, the geographical range of A. selvagensis southeastward from the Selvagens Islands to the Cape Verde Archipelago (Figure 1). MATERIAL AND METHODS One specimen of Atlanta selvagensis was separated from a sample with code 11C05D19, collected during Cruise TFMCBMCV/05 to the Cape Verde archipelago aboard the Oceanographic Vessel “Pixape” during June, 2005. The sample was obtained by a vertical haul from 1000 m of depth to the surface, using a modified triple WP-2 net system with 200 µm mesh net. The sample was fixed in 4% formalin-seawater solution, and transferred after one week to 70% ethanol for long-term storage. Sample Code Date Time (start/end) 13:03 11C05D-19 11/Jun/2005 14:13 Latitude, Longitude Bottom Depth (m) 15º 58’ 45.5’’ N 23º 07’ 20.8’’ W 1158 Table I. Characteristics of the station where the specimen of A. selvagensis was collected, during Cruise TFMCBMCV/05 (see de Vera & Seapy, 2006 for cruise code explanation). 139 Imagen en BN Fig. 1. Actual distribution of A. selvagensis in Northeastern Atlantic Ocean. The white dots correspond to the locations where this species has been collected (image modified from Google Earth). 140 RESULTS AND DISCUSSION Phyllum MOLLUSCA Class GASTROPODA CUVIER, 1797 Subclass PROSOBRANCHIA MILNE EDWARDS, 1848 Superorder CAENOGASTROPODA COX, 1960 Superfamily PTEROTRACHEOIDEA RAFINESQUE, 1814 Family ATLANTIDAE RANG, 1829 Genus Atlanta LESUEUR, 1817 Atlanta selvagensis de Vera and Seapy, 2006 Specimen small, with a diameter of 0.9 mm. Keel mostly absent and shell partially dissolved (figs. A-B); presumably resulting from the acidity of the formalin fixative. Primary features that distinguish this specimen as A. selvagensis are the number of spire whorls (3 and ¾; fig.A), the very low, conical spire with incised sutures, the violet pigmentation of the sutures (fig. C-D) and the type a eyes (fig. A). With regard to spiral sculpture on the spire whorls, the first two are smooth, and at the beginning of the third whorl a thin spiral ridge appears near the suture that continues in the first quarter of the whorl. From this point, up to 3 spirals ridges appear, but tend to disappear towards the end of the third whorl, leaving the surface of the fourth whorl smooth. Further analysis using the SEM -not recommended yet since it is a unique museum collection piece of a scarce species in the world- would allow seeing the complete spiral sculpture of this specimen. The authors didn’t remove the operculum for the same reason. Nevertheless, observations of the shell spire using the compound microscope coincide completely with the original description of the species (de Vera & Seapy, 2006). Despite the examination by the senior author of hundreds of samples deposited in the TFMC, only the one specimen reported here was discovered. More specifically, analysis of planktonic molluscs from the previous cruises to Cape Verde carried out by TFMC in 1998, has not contributed new specimens of A. selvagensis (de Vera et al., in preparation). In the original description of A. selvagensis (de Vera and Seapy, 2006), noted that “it is not plausible that this species is restricted to the Selvagens archipelago”, since the Selvagens Islands are immersed in the Macaronesian biogeographic area (in the descending oriental branch of the Gulf Stream, known as Canary Stream). The hypothesis of its presence at least along the North Atlantic Ocean turns out to be reinforced by the current record. 141 Fig. 2. Details of Atlanta selvagensis specimen collected in Cape Verde. A: Right lateral view; B: Left lateral view; C: Apertural view; D: Spire detail. LITERATURE CITED DE VERA, A. & R. R. SEAPY (2006). Atlanta selvagensis, a new species of heteropod mollusc from the Northeastern Atlantic Ocean (Gastropoda: Carinarioidea). Vieraea 34: 45-54. Fecha de recepción: 3 abril 2008 Fecha de aceptación: 5 mayo 2008