Pusillina inconspicua ( Alder, 1844 )

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 : 33-34

Pusillina inconspicua ( Alder, 1844)

( Fig. 20 )

Material examined. (12 empty shells and 23 with soft parts in 8 samples): SPAIN • 1 sPc; 43° 52.823′N, 008° 56.151′W to 43° 52.837′N, 008° 55.597′W; 988– 920 m; 08–15 SeP. 2002; DIVA-Artabria I DRN-1000 • 5 spc (1 juv); 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; 43° 26.703′N, 008° 30.669′W to 43° 27.452′N, 008° 29.612′W; 103– 102 m; 10–20 SeP. 2003; DIVA-Artabria I EBS-100 • 1 sh; 43° 40.250′N, 008° 43.755′W to 43° 40.760′N, 008° 42.120′W; 207– 197 m; 10–20 Sep. 2003; DIVA-Artabria I EBS-200 • 5 sPc; 43° 29.412′N, 008° 28.362′W to 43° 29.779′N, 008° 28.240′W; 110– 111 m; 17–28 Sep. 2004; VERTIDOS GA-AT-110 • 10 sPc + 10 sh; 42° 30.391′N, 009° 19.517′W to 42° 29.428′N, 009° 17.924′W; 147–148 m; 17–28 SeP. 2004; VERTIDOS AG-EBS-150 • 1 sPc: 42° 31.176′N, 009° 23.380′W to 42° 32.132′N, 009° 24.151′W; 242–248 m; 17–28 SeP. 2004; VERTIDOS AG-EBS-250 • 1 sPc; 42° 50.507′N, 009° 25.773′W to 42° 48.810′N, 009° 25.198′W; 151– 148 m; 17–28 SeP. 2004; VERTIDOS CA-EBS-150 .

Remarks. A species-complex can hide under the name Pusillina inconspicua ( Gofas & Oliver 2011) due its variability, its discontinuous geographic distribution along the eastern Atlantic from Norway to Angola, including the Mediterranean, and due the different habitats where the species supposedly lives, from sublittoral to bathyal bottoms below 100 m depth, and even in brackish lagoon areas ( Gofas & Oliver 2011). Cordeiro & Ávila (2015) also recorded P. inconspicua in the Azores.

The shells found in the samples studied exhibited a remarkable variability ranging from weak axial ribs, thickened lip, curved columella and closed umbilicus ( Fig. 20a ), to almost smooth surface with incised peripheral lines, thin lip, straightened columella and narrow umbilicus ( Fig. 20b ). The protoconch bears a characteristic spiral microcord close to the suture ( Figs. 20c, g ). Transition between protoconch I and II well delimited ( Figs. 20d–f ).

Shells with soft parts have been found in samples collected between 111–248 m depth on muddy sand bottoms, and one specimen at 920 m. It should be noted that some micromolluscs living in coastal algae could be swept by the currents away from the coast.

Figures

FIGURE 20. Pusillina inconspicua (Alder, 1844) (VE:AG-EBS-150). a Shell (1.5 mm); b Shell (1.2 mm); c Lateral view of the protoconch; d Detail of the embryonic/larval protoconch transition (arrow); e embryonic protoconch. f Variable sculpture of wide axial ribs very weak or almost totally missing; g Spiral micro-cord close to the suture of the protoconch.