Benthonella communis, 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 : 344-347

Benthonella communis n. sp.

( Figs 4 A-G; 5H-J; 25C; 26C; Tables 1 ; 2)

urn:lsid:zoobank.org:act:C42E14D5-7CED-4B62-BA1A-CAC05282C3E4

TYPE MATERIAL. — Holotype. Tarava Seamounts • dd (height 2.2 mm, width 1.45 mm, Figs 9 A-C; 10H-J); Mont Ari’i Moana , TARASOC Stn DW3309 ; 19°12’S, 151°35’W; 614-664 m depth; MNHN-IM-2000-37670 .

Paratypes. Tarava Seamounts • 13 dd; same locality data as holotype; MNHN-IM-2000-37671 • 11 dd; Mont Ari’i Moana, TARASOC Stn DW3311; 19°12’S, 151°33’W; 24.IX.2009; 571-586 m depth; MNHN-IM-2000-37672 • 50 dd; Mont Ari’i Moana, TARASOC Stn DW3319; 19°14’S, 151°32’W; 25.IX.2009; 480 m depth; MNHN-IM-2000-37673 • 24 dd; Mont Ari’i Moana, TARASOC Stn DW3318; 19°15’S, 151°31’W; 25.IX.2009; 557-569 m depth; MNHN-IM-2000-37674 • 6 dd; Mont Ari’i Moana, TARASOC Stn DW3321; 19°13’S, 151°32’W; 25.IX.2009; 540-572 m depth; MNHN-IM-2000-37675 • 4 dd; Mont Ari’i Moana, TARASOC Stn DW3310; 19°13’S, 151°37’W; 24.IX.2009; 613-698 m depth; MNHN-IM-2000-37676 • 126 dd; Mont Ari’i Moana, TARASOC Stn DW3316 519- 19°14’S, 151°33’W; 24.IX.2009; 520 m depth; MNHN-IM-2000-37677.

TYPE LOCALITY. — Tarava Seamounts, Mont Ari’i Moana,TARASOC Stn DW3309; 19°12’S, 151°35’W; 614-664 m depth.

OTHER MATERIAL EXAMINED. — Society Islands • 22 dd; Maupiti, TARASOC Stn DW 3407; 16°32’S, 152°31’W; 12.X.2009; 445- 645 m depth; MNHN • 5 dd; Moorea, TARASOC Stn DW 3481; 17°29’S, 149°45’W; 22.X.2009; 610 m depth; MNHN • 20 dd; Tahiti, TARASOC Stn DW 3484; 17°47’S, 149°23’W; 23.X.2009; 300-650 m depth; MNHN • 2 dd; Bora Bora, TARASOC Stn DW 3416; 16°35’S, 151°44’W; 13.X.2009; 914 m depth; MNHN • 1 dd; Huahine, TARASOC Stn DW 3420; 16°46’S, 151°04’W; 14.X.2009; 550 m depth; MNHN • 1 dd; Raiatea, TARASOC Stn DW 3451 16°53’S, 151°21’W; 18.X.2009; 440-490 m depth; MNHN. Tarava Seamounts • 33 dd; Mont Punu Taipu, TARASOC Stn DW 3302; 19°15’S, 150°57’W; 23.IX.2009; 600-660 m depth; MNHN • 2 dd; Mont Punu Taipu, TARASOC Stn DW 3300; 19°19’S, 151°00’W; 22.IX.2009; 670-757 m depth; MNHN.

Tuamotu • 6 dd; SW Kaukura, TARASOC Stn DW3359; 15°57’S, 147°08’W; 1.X.2009; 462-980 m depth; MNHN • 3 dd; Kaukura , TARASOC Stn DW 3373; 15°41’S, 146°54’W; 4.X.2009; 507-607 m depth; MNHN • 4 dd; between Tikehau and Rangiroa ,TARASOC Stn DW 3349; 15°05’S, 148°03’W; 30.IX.2009; 976-997 m depth; MNHN. Australes • 11 dd; Récif Neilson , BENTHAUS Stn DW 1924; 27°01’S, 146°05’W; 12.XI.2002; 340-800 m depth; MNHN • 1 dd; Récif Neilson , BENTHAUS Stn DW 1925; 27°00’S, 146°05’W; 12.XI.2002; 560-790 m depth; MNHN • 10 dd; Banc Mac Donald , BENTHAUS Stn DW 1875; 28°59’S, 140°15’W; 4.XI.2002; 110-150 m depth; MNHN • 29 dd; Banc Président Thiers , BENTHAUS Stn DW 1933; 24°41’S, 146°01’W; 14.XI.2002; 500-850 m depth; MNHN • 54 dd; Banc Président Thiers , BENTHAUS Stn DW 1932; 24°41’S, 146°02’W; 14.XI.2002; 500-800 m depth; MNHN • 40 dd; Marotiri , BENTHAUS Stn DW 1885; 27°52’S, 143°33’W; 6.XI.2002; 700- 800 m depth; MNHN • 3 dd; Rimatara , BENTHAUS Stn DW 2012; 22°38’S, 152°50’W; 25.XI.2002; 270-320 m depth; MNHN • 188 dd, 1 lv; Banc Arago, BENTHAUS Stn DW 1979; 23°21.7’S, 150°43.9’W; 21.XI.2002; 176-340 m depth; MNHN • 1 dd; Banc Arago, BENTHAUS Stn DW 1973; 23°23.5’S, 150°43.9’W; 20.XI.2002; 200-350 m depth; MNHN • 2 dd; Banc Arago, BENTHAUS Stn DW 1974; depth 23°24’S, 150°44’W; 20.XI.2002; 450-618 m depth; MNHN • 1 dd; Banc Arago, BENTHAUS Stn DW 1975; 23°24’S, 150°44’W; 20.XI.2002; 600-691 m depth; MNHN • 29 dd; South coast of Rurutu , BENTHAUS Stn DW 2010; 22°32’S, 151°21’W; 24.XI.2002; 520-950 m depth; MNHN • 1200+ dd; North coast of Rurutu , BENTHAUS Stn DW 1998; 22°25’S, 151°22’W; 23.XI.2002; 250-302 m depth; MNHN • 6 dd; Marotiri , BENTHAUS Stn DW 1886; depth 27°51’S, 143°32’W; 6.XI.2002; 620-1000 mdepth; MNHN • 8 dd; East coast of Rurutu , BENTHAUS Stn DW 2003; 22°27.6’S, 151°18.9’W; 24.XI.2002; 250-330 m depth; MNHN • 9 dd; North coast of Raivavae , BENTHAUS Stn DW 1943; 23°49’S, 147°39’W; 24.XI.2002; 950 m depth; MNHN • 8 dd; North of Raivavae , BENTHAUS Stn DW 1941; 23°49’S, 147°42’W; 15.XI.2002; 290-620 m depth; MNHN • 7 dd; Marotiri , BENTHAUS Stn DW 1884; 27°54’S, 143°33’W; 6.XI.2002; 570-620 m depth; MNHN • 50 dd; Tubuai , BENTHAUS Stn DW 1962; 23°21’S, 149°33’W; 19.XI.2002; 470-800 m depth; MNHN • 17 dd; Tubuai , BENTHAUS Stn DW 1955; 23°19’S, 149°26’W; 18.XI.2002; 750-850 m depth; MNHN • 69 dd; Tubuai , BENTHAUS Stn DW 1961; 23°21’S, 149°34’W; 19.XI.2002; 470-800 m depth; MNHN • 1000+ dd; Banc Lotus , BENTHAUS Stn DW 1951; 23°49’S, 147°53’W; 17.XI.2002; 206-450 m depth; MNHN • 118 dd; East of Rapa , BENTHAUS Stn DW 1889; 27°37’S, 144°16’W; 7.XI.2002; 600-620 m depth; MNHN • 60 dd; Rimatara , BENTHAUS Stn DW 2021; 22°37’S, 152°49’W; 25.XI.2002; 1200-1226 m depth; MNHN • 77 dd; Rimatara , BENTHAUS Stn DW 2020; 22°37’S, 152°49’W; 25.XI.2002; 920-930 m depth; MNHN .

DISTRIBUTION AND SYMPATRY. — The species is at present known in the South Pacific Ocean from the Tarava Seamounts (Mont Ari’i Moana, Mont Punu Tipu), Society Islands (Maupiti, Moorea, Huahine, Tahiti, Bora Bora, Raiatea), Tuamotu (WS Kaukura, Kaukura, between Tikehau and Rangiroa) and Australes (Récif Neilson, Banc Mac Donald, Banc Président Thiers, Marotiri, Rimatara, Banc Arago, North coast of Rurutu, Tubuai, South coast of Rurutu, East coast of Rurutu, North coast of Raivavae, Banc Lotus, East coast of Rapa), with empty shells collected in 110-1226 m depth, and one live specimen collected at Australes, Banc Arago in 176-340 m depth ( Fig. 25C ). Benthonella communis n. sp. is sympatric with Benthonella boucheti n. sp. at the Australes (Récif Neilson, Banc Président Thiers, Marotiri, Rimatara, Banc Arago, Tubuai, South coast of Rurutu, East coast of Rurutu, North coast of Raivavae), Tuamotu (between Tichehau and Rangiroa); with Benthonella basistriata n. sp. at the Tuamotu (Kaukura), Society Islands (Huahine, Moorea); with Benthonellania maestratii n. sp. at the Australes (Récif Neilson, South coast of Rurutu); with Benthonellania bouteti n. sp. at the Tarava Seamounts (Mont Ari’i Moana, Mont Punu Tipu), Society Islands (Maupiti, Moorea, Huahine, Tahiti, Bora Bora, Raiatea), Tuamotu (WS Kaukura, Kaukura, entre Tichehau & Rangiroa), Australes (Récif Neilson, Banc Président Thiers, Rimatara, Banc Arago, North coast of Rurutu, South coast of Rurutu, East coast of Rurutu, Banc Lotus, East of Rapa, Tubuai); with Benthonellania tarava n. sp. at the Tarava Seamounts (Mont Ari’i Moana), Society Islands (Moorea), Tuamotu (WS Kaukura, Kaukura, between Tichehau and Rangiroa), Australes (Rimatara, South coast of Rurutu, East coast of Rimatara); with Benthonellania tuamotu n. sp. at the Tarava Seamounts (Mont Punu Tipu), Society Islands (Maupiti, Raiatea), Tuamotu (WS Kaukura, Kaukura, between Tikehau and Rangiroa), Australes (Rimatara, South coast of Rurutu, Récif Neilson); with Benthonellania megan n. sp. at the Australes (Rimatara); with Benthonellania alis 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) ( Table 2).

ETYMOLOGY. — For the large number of specimens found, (Latin) communis – common.

DESCRIPTION OF HOLOTYPE.

Shell ( Figs 4 A-C; 5H-J)

Small for the genus, height 2.2 mm, width 1.45 mm, height/ width ratio 1.517, not very solid, ovate-conical.

Protoconch ( Figs 4E, F ; 5I, J ; Table 1 )

Multispiral, dome-shaped, of 2.3 whorls, height 0.30 mm, nucleus diameter 0.05 mm, first half whorl diameter 0.112 mm, maximum diameter 0.425 mm; protoconch I with sparse microtubercles and traces of spiral threads (embryonic shell in poor condition) ( Fig. 5J ), protoconch II with two fine and slightly wavy spiral cordlets, and a series of axial L-shaped subsutural rodlets between abapical cordlet and suture on the last half protoconch whorl ( Fig. 5I ). Protoconch-teleoconch boundary indistinct, sinuous.

Teleoconch

Of 3.25 slightly convex whorls, suture canaliculate, crowned by small tubercles on tip of axial ribs. Height last whorl 1.575 mm. height/height last whorl ratio 1.396. Axial sculpture of 27 flexuose, opisthocline ribs on last whorl, as broad as the interspaces, abruptly interrupted before the base. Spiral sculpture absent.Microsculpture of only growth striae ( Fig. 5I ). Umbilical chink present. Aperture pyriform, small, height 1.0 mm, height/height aperture ratio 2.200, peristome continuous, varix weak; outer lip opisthocline, sharp, internally smooth. Columella arcuate simple.

Colour

Coloration of teleoconch white, outer lip pale orange, slightly darker adapically, protoconch pale whitish-orange.

Operculum and soft parts

Unknown.

VARIABILITY

Species not very variable (see Table 1 and Appendix 3). Minimum height 1.27 (from North coast of Rurutu, 250- 302 m); maximum height 2.40 (from Mont Ari’i Moana, 614-664 m). Variable number of axial ribs: 16-27. In about 10% of specimens examined, the external lip presents a more or less conspicuous angulation ( Fig. 4G ). The axial ribs are thinner when they are more numerous.

REMARKS

The axial ribs abruptly stopping before the base (around the maximum diameter of the whorl), generate a sort of false spiral cord.

Benthonella olangoensis from the Philippines, is very similar to Benthonella communis n. sp. in the general shape, but is distinguished by the presence of 2-3 spiral cordlets vs absent in B. communis n. sp.

Benthonella brontodes Lozouet, 1990 , from the upper Oligocene of the Aquitaine basin ( France), is very similar to B. communis n. sp., but differs mainly in its different protoconch, narrower and lower (height 151 µm and maximum diameter 379 µm vs height 0.275 -0.325 mm and maximum diameter 0.400 - 0.437 mm in B. communis n. sp.), and with different sculpture: with a fine median cordlet, doubled in the first half whorl vs two fine and slightly wavy spiral cordlets, and a series of axial L-shaped subsutural rodlets between abapical cordlet and suture on the last half protoconch whorl ( Fig. 10I ) in B. communis n. sp. (see Lozouet 1990: 325, figs 24-25).

Figures

FIG. 4. — Benthonella communis n. sp.: A-C, holotype, height 2.2 mm, width 1.45 mm, Tarava Seamounts,TARASOC Stn DW3309 614-664 m 19°12’S, 15°35’W (MNHN-IM-2000-37670); D-F, specimen, height 2.35 mm, width 1.5 mm, Australes: BENTHAUS Stn DW1998 250-302 m 22°25’S, 151°22’W, MNHN; G, specimen, height 2.01 mm, width 1.35 mm, Australes: BENTHAUS Stn DW1998, 250-302 m, 22°25’S, 151°22’W, MNHN. Scale bars: E, F, 0.25 mm.

FIG. 9. — Benthonellania spp. (SEM): A, B, Benthonellania hertzogi (Thiele, 1925), syntype, Agulhas-Bank (south of South Africa), height 2.85 mm, ZMB/Moll. no. 64981, shell (A), detail of the protoconch (B); C, D, Benthonella africana (Thiele, 1925) n. comb., lectotype, East Africa (off Somalia), height 3.85 mm, ZMB/ Moll. No. 64955a, shell (C), detail of the protoconch (D). Scale bars: B, D, 100 μm.

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. 5. — Benthonella spp. (SEM): A-E, Benthonella boucheti n. sp. holotype, MNHN-IM-2000-37666, Tarava Seamounts, height 4.32 mm: A, shell; B, C, detail of the protoconch microsculture; D, detail of the teleoconch sculpture spiral; E, detail of the first whorls; F, G, Benthonella basistriata n. sp. holotype, MNHN- IM-2000-37668, Tuamotu,height 2.0 mm:F, shell; G, detail of the protoconch microsculture;H-J, Benthonella communis n. sp., holotype,MNHN-IM-2000-37670, Tarava Seamounts: height 2.2 mm; H, shell; I, J, detail of the protoconch microsculture. Scale bars: B, 40 μm; C, J, 20 μm; D, E, I, 100 μm; G, 50 μm.

FIG. 10. — Benthonellania thielei n. sp., Valdivia Stn 251, East Africa, 693 m depth: A-C, holotype, height 3.05 mm width 1.92 mm, ZMB/Moll. No. 64955a; D-F, paratype,height 2.8 mm, ZMB/Moll.No. 64955b; G-L, paratype,height 2.97 mm, ZMB/Moll. No. 64955b; J, K, detail of the first whorls,L, detail of the spiral sculpture on the last teleoconch whorl; M, original label; N, original drawing (Thiele 1925, 83, pl. 6, fig. 21). Scale bars: J, K, L, 0.50 mm.