Benthonella tenella ( Jeffreys, 1869 )

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 : 29-30

Benthonella tenella ( Jeffreys, 1869)

( Fig. 17 )

Material examined. (15 empty shells and 9 with soft parts in 7 samples): SPAIN • 3 sh + 2 spc; 43° 57.030′N, 008° 54.795′W to 43° 57.248′N, 008° 54.133′W; 1191– 1132 m; 08–15 SeP. 2002; DIVA-Artabria I AT-1000 • 2 sPc; 43° 35.451′N, 008° 34.432′W to 43° 34.810′N, 008° 35.407′W; 153– 151 m; 08–15 SeP. 2002; DIVA-Artabria I EBS-150 • 1 sh + 3 sPc; 43° 48.587′N, 008° 51.402′W to 43° 49.545′N, 008° 51.197′W; 610– 598 m; 10–20 SeP. 2003; DIVA-Artabria I EBS-600 • 4 sPc + 7 sh; 42° 45.9′N, 009° 41.68′W to 42° 47.00′N, 009° 42°.12′W; 1499– 1373 m; 15–30 Sep. 2008; DIVA-Artabria II EBS-27 • 3 sh; 42° 38.21′N, 009° 51.46′W to 42° 39.45′N, 009° 50.73′W; 1961–1971 m; 15–30 Sep. 2008; DIVA-Artabria II EBS-28 • 1 sPc; 42° 27.66′N, 009° 46.13′W to 42° 29.08′N, 009° 45.31′W; 2033–2091 m; 15–30 SeP. 2008; DIVA-Artabria II EBS-29 • 1 sh; 42° 29.55′N, 01010.5′W to 42° 30.08′N, 01° 009.57′W; 2798– 2765 m; 14–25 Feb. 2009; FORSAGAL EBS-4 .

Remarks. Benthonella tenella is the most common Atlantic and Mediterranean bathyal rissoid species, with the widest geographic and bathymetric range of all. It is distributed on both sides of the Atlantic, from Iceland to the Caribbean in the west and to the Macaronesian islands in the east, and in the whole Mediterranean basin, being also patchily present in the southern Atlantic ( Bouchet & Warén 1993; Hoffman et al. 2011; Sysoev 2014; Negri & Corselli 2016). It is also common in the northeastern Atlantic seamounts ( Gofas 2007). Its planktotrophic development with ontogenetic vertical migration allows the potential for large-scale dispersal ( Rex & Etter 1990). Nevertheless, in the samples studied it has not been very abundant, having been found between 1400 and 2100 m. The few shells found in the samples belong to the smooth morph ( Fig. 17a ). Multispiral protoconch with just over three whorls. The embryonic whorls show three fine spiral lines and microgranules in between ( Figs. 17d–e, g ). Subsequent whorls (protoconch II) with two suprasutural spiral threads ( Figs. 17b, f ), the upper one like a keel framing a flattened shoulder ( Fig. 17c ).

Figures

FIGURE 17. Benthonella tenella (Jeffreys, 1869) (DA-II(08): EBS-27). a Shell (3.2 mm); b–c protoconch and detail of the growth lines; d–e embryonic protoconch and detail of its microsculpture; f–g lateral of other protoconch and detail of its embryonic protoconch.