Alvania proditoris ( Thiele, 1925 ) Amati & Giulio & Oliverio, 2023

Amati, Bruno, Giulio, Andrea Di & Oliverio, Marco, 2023, Shallow-water Rissoidae of the genera Alvania Risso 1826 Haurakia Iredale 1915 Parashiela Laseron 1956 Simulamerelina Ponder 1985 and Subestea Cotton 1944 Gastropoda Caenogastropoda Rissooidea from French Polynesia with the description of a new deep-water genus, Zoosystema 45 (25), pp. 803-892 : 807-808

Alvania proditoris ( Thiele, 1925) n. comb.

( Figs 3 ; 48 )

Rissoa proditoris Thiele, 1925: 80 , pl. 6, fig. 9.

TYPE MATERIAL. — Lectotype. South Africa • dd; Valdivia Stn 101 ; 33°50’27”S, 25°48’46”E; ZMB/Ma.64965 (here designated). Paralectotypes. South Africa • 5 dd; Valdivia Stn 95 ; 34°51’0”S, 19°37’47”E; 80 m; ZMB/Ma.64965 • 3 dd; Valdivia Stn 101 ; 33°50’27”S, 25°48’46”E; ZMB/Ma.64965 .

Angola • 1 dd; Valdivia Stn 81 ; 16°26’27”S, 11°41’27”E; ZMB/ Ma.64965 .

TYPE LOCALITY. — South Africa, Valdivia Stn 101; 33°50’27”S, 25°48’46”E.

DISTRIBUTION. — Only known from southern Africa (Valdivia Stns 95 and 101) and from a station in southern Angola (Valdivia Stn 81) ( Fig. 48 ).

DIAGNOSIS. — Alvania with small (height <3 mm), robust shell, ovate-conical; spiral sculpture stronger than axial; aperture piriform, peristome continuous and simple, outer lip with robust; umbilical fissure absent. Protoconch paucispiral, dome-shaped, with spiral sculpture. Colouration uniform whitish.

REMARKS

The lot from southern Angola (Valdivia Stn 81) comes form a completely distinct biogeographic area, and we are not sure it is not a case of mislabelling. In any case, to stabilize the type locality we have designated as lectotype a specimen from the Cape area (Valdivia Stn 95). Rissoa proditoris Thiele, 1925 is clearly a member of Alvania , with its shell devoid of umbilical fissure, with double sculpture (axial and spiral), piriform aperture, continuous and simple peristome, outer lip with robust varix, dome-shaped paucispiral protoconch with spiral sculpture. We accordingly propose Alvania proditoris ( Thiele, 1925) n. comb. as a new combination for Rissoa proditoris Thiele, 1925 .

Figures

FIG. 3. — Alvania proditoris (Thiele, 1925) n. comb.: A-E, lectotype, height 2.75 mm, width 1.65 mm, South Africa, Valdivia Stn 101, depth unknown, ZMB/Moll. N° 64965: shell (A-C); detail of the first whorls (D, E); F, original labels; G, original drawing. Scale bars: D, E, 20 μm.

FIG. 48. — Distribution maps of the Polynesian species of Alvania Risso, 1826 and Ellenstrongia n. gen.: A, Alvania letourneuxi n. sp. (●) and Alvania herosae n. sp. (○); B, Alvania parvimaculata n. sp. (○) and Alvania prosocostata n. sp. (●); C, Alvania uapou n. sp.; D, Ellenstrongia tarasoc n. gen., n. sp.