Benthonellania alis, Amati & Giulio & Oliverio, 2022

Amati, Bruno, Giulio, Andrea Di & Oliverio, Marco, 2022, Deep-water Rissoidae of the genera Benthonella Dall, 1889 and Benthonellania Lozouet, 1990 (Gastropoda, Caenogastropoda, Rissooidea) from French Polynesia, Zoosystema 44 (12), pp. 335-389 : 361-363

Benthonellania alis n. sp.

( Figs 15 A-H; 16F-H; 25E; 26J; Tables 1 ; 2)

urn:lsid:zoobank.org:act:42BB5584-4C5F-4386-A53B-7E5B2F088541

TYPE MATERIAL. — Holotype. Australes • 1 dd (height 3.35, width 1.87 mm, Figs 15 D-G; 16F-H); South coast of Rurutu , BENTHAUS Stn DW2010 ; 22°32’S, 151°21’W; 24.XI.2002; 520-950 m depth; MNHN-IM-2000-37685 .

Paratypes. Australes • 87 dd; same data as holotype; MNHN- IM-2000-37686 .

TYPE LOCALITY. — Australes, South coast of Rurutu, BENTHAUS Stn DW2010; 22°32’S, 151°21’W; 520-950 m depth.

OTHER MATERIAL EXAMINED. — Australes • 23 dd; East coast of Rurutu, BENTHAUS Stn DW 2004; 22°27.7’S, 151°18.7’W; 24.XI.2002; 430-850 m depth; MNHN • 12 dd; Rimatara, BENTHAUS Stn 2020; 22°37’S, 152°49’W; 25.XI.2002; 920- 930 m depth; MNHN • 8 dd; Rimatara, BENTHAUS Stn DW 2021 22°37’S, 152°49’W; 25.XI.2002; 1200-1226 m depth; MNHN • 2 dd; Marotiri, BENTHAUS Stn DW 1886; 27°51’S, 143°32’W; 6.XI.2002; 620-1000 m depth; MNHN • 3 dd; Tubuai, BENTHAUS Stn DW 1955; 23°19’S, 149°26’W; 18.XI.2002; 750-850 m depth; MNHN • 12 dd; Banc Président Thiers, BENTHAUS Stn DW 1932; 24°41’S, 146°02’W; 14.XI.2002; 500-800 m depth; MNHN • 11 dd; East coast of Rapa, BENTHAUS Stn DW 1889; 27°37’S, 144°16’W; 7.XI.2002; 600-620 m depth; MNHN .

Tarava Seamounts • 5 dd; Mont ‘ Otaha, TARASOC Stn DW 3328; 18°46’S, 152°15’W; 26.IX.2009; 788-836 m depth; MNHN • 1 dd; Mont Punu Taipu, TARASOC Stn DW 3300; 19°19’S, 151°00’W; 22.IX.2009; 670-757 m depth; MNHN • 3 dd; Mont ‘ Otaha, TARASOC Stn DW 3329; 18°45’S, 152°16’W; 20.IX.2009; 755- 840 m depth; MNHN • 15 dd; Mont ‘ Otaha, TARASOC Stn DW 3327; 18°45’S, 152°16’W; 26.IX.2009; 747-836 m depth; MNHN • 3 dd; Mont Honu, TARASOC Stn DW 3340; 18°24’S, 154°09’W; 27.IX.2009; 787-792 m depth; MNHN .

Society Islands • 2 dd; Bora Bora, TARASOC Stn DW 3416; 16°36’S, 151°44’W; 13.X.2009; 914 m depth; MNHN .

DISTRIBUTION AND SYMPATRY. — The species is at present known from the South Pacific Ocean, at Australes (East coast of Rurutu, South coast of Rurutu, Rimatara, Marotiri, Tubuai, Banc Président Thiers, East of Rapa), Tarava Seamounts (Mont ‘Otaha, Mont Punu Taipu, Mont Honu), Society Islands (Bora Bora), with only empty shells collected in 430-1226 m depth ( Fig. 25E ).

Benthonellania alis n. sp. is sympatric with Benthonella boucheti n. sp. at the Australes (East coast of Rurutu, South coast of Rurutu, Rimatara, Marotiri, Tubuai, Banc Président Thiers), Tarava Seamounts (Mont ‘Otaha); with Benthonellania maestratii n. sp. at the Australes (South coast of Rurutu); with Benthonella communis n. sp. at the Tarava Seamounts (Mont Punu Taipu), Australes (East coast of Rurutu, South coast of Rurutu, Rimatara, Marotiri, Tubuai, Banc Président Thiers, East of Rapa), Society Islands (Bora Bora); with Benthonellania bouteti n. sp. at the Tarava Seamounts (Mont ‘Otaha, Mont Punu Taipu, Mont Honu), Australes (East coast of Rurutu, South coast of Rurutu, Rimatara; Banc Président Thiers, East of Rapa, Tubuai); with Benthonellania tarava n. sp. at the Tarava Seamounts (Mont ‘Otaha, Mont Honu), Australes (Rimatara, South coast of Rurutu, East coast of Rurutu); with Benthonellania tuamotu n. sp. at the Tarava Seamounts (Mont ‘Otaha, Mont Punu Taipu), Australes (Rimatara, South coast of Rurutu); with Benthonellania megan n. sp. at the Australes (Rimatara) ( Table 2).

ETYMOLOGY. — Dedicated to the research vessel ‘Alis’ and its crew, which during decades so greatly contributed to the increase of knowledge of the Pacific deep-water fauna.

DESCRIPTION OF HOLOTYPE

Shell ( Figs 15 D-G; 16G-H)

Large for the genus, height 3.35 mm width 1.79 mm, height/ width ratio 1.875, rather solid, ovate-conical.

Protoconch ( Figs 15D ; 16G, H ) Slender, acute, multispiral, of 2.3 whorls, height 0.337 mm, nucleus diameter 0.075 mm, first half whorl diameter 0.175 mm, maximum diameter 0.412 mm; protoconch I with 4 spiral cordlets of concatenated microtubercles ( Fig. 16H ), protoconch II with 3 zig-zag spiral cordlets on upper part, and a fourth irregular cordlet on lower part ( Fig. 16G ). Protoconch-teleoconch boundary barely visible, opisthocline, sinuous.

Teleoconch

Of 4 slightly convex whorls, suture canaliculate, crowned by small tubercles at tips of axial ribs, highlighted by a subsutural spiral groove. Height last whorl 2.2 mm, height/height last whorl ratio 1.522. Axial sculpture of 20 ribs on last whorl, as broad as the interspaces, opisthocline on first whorls, then orthocline, and slightly prosocline on last whorl, gradually vanishing at the base; last half whorl progressively devoid of axial sculpture. Spiral sculpture of 3 very weak cordlets on the suture line, the uppermost suprasutural visible on all whorls, base smooth ( Fig. 15H ). Microsculpture of only growth striae. Umbilical chink absent. Aperture pyriform, large, height 1.23 mm, height/height aperture ratio 2.723, peristome continuous, varix absent (outer lip broken). Columella arcuate, simple.

Colour

Coloration of teleoconch white, protoconch orange.

Operculum and soft parts

Unknown.

VARIABILITY

Species not very variable (See Table 1 and Appendix 9).

REMARKS

Most of the examined specimens have the outer lip broken; where the peristome is intact, no thickening was observed.

B. alis n. sp. is very similar to B. bouteti n. sp. but can be distinguished by the presence of 3-4 fine spiral cords on the last whorl vs absence of spiral sculpture in B. bouteti n. sp.; the protoconch with 4 spiral cordlets of concatenated microtubercles on protoconch I, and 3 zig-zag spiral cordlets on upper part, and a fourth irregular cordlet on lower part vs protoconch with six threads and microtubercles on protoconch I and 5 spiral cordlets (the three adapical with a zig-zag pattern) of concatenated dart-like microtubercles on protoconch II in B. bouteti n. sp.

B. alis n. sp. is also similar to Benthonellania africana ( Thiele, 1925) n. comb. ( Figs 11 A-N; 13A, B) from which it differs mostly in its multispiral protoconch with marked spiral sculpture vs paucispiral and smooth, except for a faint and confused spiral sculpture on the nucleus in B. africana n. comb.

See under Benthonellania aequatorialis ( Thiele, 1925) n. comb. for differences with this species.

Figures

FIG. 15. — Benthonellania alis n.sp.:A-C, specimen,height 3.7 mm,width 2.15 mm,Australes:BENTHAUS Stn DW2020,920-930 m, 22°37’S,152°49’W,MNHN;D-G, holotype,height 3.35,width 1.87 mm,Australes:BENTHAUS Stn DW2010 520-950 m,22°32’S,151°21’W, MNHN-IM-2000-37685; H, paratype,Australes:BENTHAUS Stn DW2010, 520-950 m, 22°32’S, 151°21’W, MNHN-IM-2000-37686, detail of the teleoconch sculpture spiral on the last whorl. Scale bars: D, 0.25 mm; H, 0.50 mm.

FIG. 25. — Distribution maps of the Polynesian species of Benthonella Dall,1889 and Benthonellania Lozouet,1990: A, Benthonella boucheti n. sp.;B, Benthonella basistriata n. sp.; C, Benthonella communis n. sp.; D, Benthonellania bouteti n. sp.; E, Benthonellania alis n. sp.; F, Benthonellania tarava n. sp. (◯) and Benthonellania lozoueti n. sp. (); G, Benthonellania megan n. sp. (◯) and Benthonellania maestratii n. sp. (); H, Benthonellania tuamotu n. sp.

FIG. 16. — Benthonellania spp. (SEM): A-E, Benthonellania bouteti n. sp. holotype, Society Islands, height 3.45 mm, MNHN-IM-2000-37678, shell (A), detail of the protoconch microsculture (B-D), detail of the teleoconch axial sculture (E); F-H, Benthonellania alis n. sp. holotype, Australes, height. 3.35 mm, MNHN- IM-2000-37685; shell (F); detail of the protoconch microsculture (G, H). Scale bars: B, C, 40 μm; D, H, 20 μm; E, 100 μm; G, 30 μm.

FIG. 11. — Benthonellania aequatorialis (Thiele, 1925) n. comb., syntypes: A-C, height 1.8 mm; D, height 1.95 mm; E, original label; F, original drawing (Thiele 1925, 84, pl. 6, fig. 23); G, syntype, detail of the first whorls; Valdivia Stn 199, ZMB-64973. Scale bar: G, 0.25 mm.