Alvania candasae Oliver & Gofas, 2022

Oliver, Joan Daniel, Gofas, Serge, Urgorri, Victoriano, Díaz-Agras, Guillermo & Templado, José, 2022, Rissoidae gastropods of the outer continental shelf and slope off Galicia (NW Spain), Zootaxa 5196 (1), pp. 1-45 : 21

Alvania candasae Oliver & Gofas sp. nov.

( Fig. 13 )

Type material. Holotype: SPAIN • 1 emPty shell ( Fig. 13 ); 42° 51.20′N, 009° 43.85′W to 42° 52.97′N, 009° 44.25′W; 1861– 1177 m; 15–30 Sep. 2008; DIVA-Artabria II DRNp-26; MHNS, deposit number: MHN-USC-10118 . Paratypes: SPAIN • 3 sh (ParatyPes 1–3); 44° 11.652′N, 008° 58.152′W to 44° 11.539′N, 008° 57.574′W; 908–1106 m; 15–24 Jul. 2008; A SELVA DRN-7 ; MHN-USC, deposit number: MHN-USC-10118; • 5 sh (1 juv) (paratypes 4–8); 43° 19.92′N, 009° 38.13′W to 43° 21.25′N, 009° 37.11′W; 1267–1286 m; 15–30 SeP. 2008; DIVA-Artabria II EBS-15 ; MNCN 15.05 /200226.

Type locality: Muxía Canyon off W Galicia (42° 51.20′– 42° 52.97′ N; 009° 43.85′– 009° 44.25′W, 1177–1861 m) .

Derivatio nominis: This species is dedicated to Dra. María Candás who has participated in the collection of samples in all oceanographic campaigns and has participated in the sorting of the samples and procedure of the species obtained.

Description. Small oval shell (1.8 x 1.1 mm in the holotype with somewhat more than 4 whorls) with moderately high conical sPire and blunt aPex ( Fig. 13a ), aPical angle of about 42°, colour white. APerture Pyriform, Pointed at union with penultimate whorl, height 0.7 mm (about 38% of total height). Teleoconch with slightly convex whorls and channeled suture highlighted by a subsutural spiral depression ( Fig. 13o ). Sculpture of weak, axial ribs almost orthocline, at about 10° with sPire axis; flat sPiral cords towards the base and minute sPiral striae ( Figs. 13j–k ) also in the channeled suture ( Fig. 13e ). On the body whorl there are about 30 ribs disappearing at the base. Rounded aperture with a thin edge, not thickened. Umbilicus open but partly covered by columellar lip; umbilical area with chink and coarse growth lines ( Figs. 13a, f, l ).

Paucispiral protoconch of just over a whorl ( Figs. 13b, c, g, m ) with inconspicuous sculpture of very weak axial threads and scattered or slightly spirally aligned microtubercles ( Figs. 13d, i ). At the base of the nucleus certain roughness can be observed under high magnification ( Fig. 13h ).

Soft parts and radulae unknown.

Remarks. Alvania candasae sp. nov. seems to belong to the same group as A. electa , A. porcupinae , A. adinogramma Bouchet & Warén, 1993 and A. cancapae Bouchet & Warén, 1993 . This last species, from off Morocco and Canary and Madeira Islands, is larger (more than 2 mm) with less numerous and more pronounced axial ribs, as well as A. electa , whose protoconch has a microsculpture of fine spiral threads and microgranules, different from that of the new species. Alvania porcupinae is also larger (more than 2 mm), its suture is not so channeled and its protoconch surface is smooth. A. adinogramma has more convex whorls, less ribbed suture, and a conspicuous spiral sculpture throughout the shell. Alvania adiaphoros Bouchet & Warén, 1993 is somewhat larger, with axial ribs more widely separated and not extending on the abapical part of the body whorl, and its channeled suture is less pronounced. Also, A. microstriata and A. seinensis , from Madeira and Seine Seamount, resemble this new species in their shape and size, but they have a shallow subsutural furrow instead of a channeled suture and their protoconch surface are densely covered by very fine microtubercles.

Nine empty shells were found in samples collected between 900 and 1600 m.

Figures

FIGURE 13. Alvania candasae Oliver & Gofas sp. nov. Holotype (DA-II(08): DRNp-26). a Shell (1.85 mm); b Lateral view of its protoconch; c Apical view of the protoconch; d Detail of its microsculpture; e Detail of the microsculpture of the subsutural furrow. Paratypes 4 and 5 (DA-II(08): EBS-15). f–k Paratype 4; f Shell (1.7 mm); g Lateral view of its protoconch; h–i Details of its microsculpture; j–k Details of microsculpture of the teleoconch; l–o Paratype 5; l Shell (1.8 mm); m–n Protoconch and detail of its microsculpture; o Detail of the sculpture of the teleoconch in the subsutural area.