Benthonellania bouteti, 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 : 358-361

Benthonellania bouteti n. sp.

( Figs 14 A-H; 16A-E; 25D; 26I; Tables 1 ; 2)

urn:lsid:zoobank.org:act:D5879068-B303-4D8B-B7B2-CC9E2F53D353

TYPE MATERIAL. — Holotype. Society Islands • dd (height 3.45 mm, width 1.9 mm, Figs 14 A-D; 16A-E); Moorea , TARASOC Stn DW3460 ; 17°28’S, 149°50’W; 19.X.2009; 660-680 m depth; MNHN-IM-2000-37678 .

Paratypes • 34 dd; same data as holotype; MNHN-IM-2000-37679 • 4 dd; Stn DW3481; 17°29’S, 149°45’W; 22.X.2009; 610 m depth; MNHN-IM-2000-37680 • 8 dd; Stn DW3461; 17°27’S, 149°49’W; 19.X.2009; 844-877 m depth; MNHN-IM-2000-37681 • 35 dd; Stn DW 3474; 17°28’S, 149°50’W; 21.X.2009; 720 m depth; MNHN-IM-2000-37682 • 2 dd; Stn DW3476; 17°29’S, 149°45’W; 21.X.2009; 435-490 m depth; MNHN-IM-2000-37683 • 18 dd, 1 lv; Stn DW3459; 17°28’S, 149°48’W; 19.X.2009; 485-560 m depth; MNHN-IM-2000-37684.

TYPE LOCALITY. — Society Islands, Moorea,TARASOC Stn DW3460, 17°28’S, 149°50’W; 660-680 m depth.

OTHER MATERIAL EXAMINED. — Society Islands • 36 dd; Huahine, TARASOC Stn DW 3425; 16°43’S, 151°03’W; 14.X.2009; 557 m depth; MNHN • 4 dd; Huahine,TARASOC Stn DW 3435; 16°41’S, 151°02’W; 15.X.2009; 500-612 m depth; MNHN • 17 dd, 1 lv; Huahine, TARASOC Stn DW 3429; 16°43’S, 150°38’W; 15.X.2009; 493-540 m depth; MNHN • 12 dd, 2 lv; Huahine, TARASOC Stn DW 3420; 16°46’S, 151°04’W; 14.X.2009; 550 m depth; MNHN • 9 dd; Huahine, TARASOC Stn DW 3426; 16°41’S, 151°03’W; 14.X.2009; 801-874 m depth; MNHN • 10 dd, 1 lv; Huahine, TARASOC Stn DW 3421; 16°46’S, 151°04’W; 14.X.2009; 782- 847 m depth; MNHN • 38 dd; Huahine, TARASOC Stn DW 3434; 16°42’S, 151°03’W; 15.X.2009; 700-785 m depth; MNHN • 10 dd; Tahiti, TARASOC Stn DW 3491; 17°29’S, 149°26’W; 24.X.2009; 440-500 m depth; MNHN • 4 dd; Tahiti, TARASOC Stn DW 3501; 17°36’S, 149°17’W; 25 Oct. 2009; 800-820 m depth; MNHN • 48 dd; Tahiti, TARASOC Stn DW 3498; 17°43’S, 149°17’W; 25.X.2009; 347-460 m depth; MNHN • 5 dd; Tahiti,TARASOC Stn DW 3487; 17°47’S, 149°21’W; 23.X.2009; 400-440 m depth; MNHN • 126 dd; Tahiti, TARASOC Stn DW 3484; 17°47’S, 149°23’W; 23.X.2009; 300-650 m depth; MNHN • 4 dd; between Raiatea and Tahaa, TARASOC Stn DW 3442; °41’S, 151°26’W; 16.X.2009; 515-550 m depth; MNHN • 6 dd; between Raiatea and Tahaa, TARASOC Stn CP 3439; 16°43’S, 151°25’W; 16.X.2009; 800 m depth; MNHN • 10 dd; between Raiatea and Tahaa ,TARASOC Stn DW3436; 16.X.2009; 430 m depth; MNHN • 7 dd, 1 lv; Raiatea , TARASOC Stn DW 3451; 16°53’S, 151°21’W; 18.X.2009; 440- 490 m depth; MNHN • 11 dd; Raiatea , TARASOC Stn DW 3452; 16°51’S, 151°19’W; 18.X.2009; 600-705 m depth; MNHN • 5 dd; Raiatea , TARASOC Stn DW 3457; 16°45’S, 151°24’W; 18.X.2009; 520-572 m depth; MNHN • 21 dd; Bora Bora, TARASOC Stn DW 3416; 16°35’S, 151°44’W; 13.X.2009; 914 m depth; MNHN • 1 dd; Bora Bora, TARASOC Stn DW 3418; 13.X.2009; 580-618 m depth; MNHN • 24 dd; Tahaa , TARASOC Stn DW 3447; 16°42’S, 151°31’W; 17.X.2009; 620-700 m depth; MNHN • 12 dd, 1 lv; Maupiti,TARASOC Stn DW3407; 16°32’S, 152°31’W; 12.X.2009; 445-645 m depth.

Tuamotu • 10 dd; SW Kaukura, TARASOC Stn DW3559; 15°57’S, 147°08’W; 1.X.2009; 462-980 m depth; MNHN • 36 dd, 2 lv; Kaukura, TARASOC Stn DW 3373; 15°41’S, 146°54’W; 4.X.2009; 507-607 m depth; MNHN • 1 dd; Tikehau ,TARASOC Stn DW 3387 550-600 m depth; 14°57’S, 148°16’W 6.X.2009; MNHN • 2 dd; Tikehau , TARASOC Stn DW 3389; 14°55’S, 148°15’W; 6.X.2009; 889 m depth; MNHN • 3 dd; between Tikehau and Rangiroa, TARASOC Stn DW 3349; 15°06’S, 148°03’W; 30.IX.2009; 976- 997 m depth; MNHN • 5 dd; between Tikehau and Rangiroa, TARASOC Stn DW 3351; 15°04’S, 148°01’W; 30.IX.2009; 976- 983 m depth; MNHN .

Tarava Seamounts • 10 dd; Mont Ari’i Moana, TARASOC Stn DW 3316; 19°14’S, 151°33’W; 24.IX.2009; 519-520 m depth; MNHN • 1 dd; Mont Ari’i Moana, TARASOC Stn DW 3317; 19°13’S, 151°29’W; 25.IX.2009; 593-668 m depth; MNHN • 9 dd; Mont Honu, TARASOC Stn DW 3340; 18°24’S, 154°09’W; 27.IX.2009; 787-792 m depth; MNHN • 5 dd; Mont Punu Taipu, TARASOC Stn DW 3302; 19°15’S, 150°57’W; 23.IX.2009; 600- 660 m depth; MNHN • 61 dd; Mont ‘ Otaha, TARASOC Stn DW 3327; 18°45’S, 152°16’W; 26.IX.2009; 747-836 m depth; MNHN • 1 dd; Mont ‘ Otaha, TARASOC Stn CP 3329; 18°45’S, 152°16’W; 26.IX.2009; 755-840 m depth; MNHN • 11 dd; Mont ‘ Otaha, TARASOC Stn DW 3328; 18°46’S, 152°15’W; 26.IX.2009; 788-836 m depth; MNHN .

Australes • 91 dd; Banc Lotus, BENTHAUS Stn DW1951; 23°49’S, 147°53’W; 17.XI.2002; 206-450 m depth • 1200+ dd (many juveniles), 7 lv; East of Rapa , BENTHAUS Stn DW 1889; 27°37’S, 144°16’W; 7.XI.2002; 600-620 m depth; MNHN • 53 dd; Tubuai , BENTHAUS Stn DW 1962; 23°21’S, 149°33’W; 19. XI.2002; 470-800 m depth; MNHN • 5 dd; Tubuai , BENTHAUS Stn DW 1955; 23°19’S, 149°26’W; 18.XI.2002; 750-850 m depth; MNHN • 28 dd; Tubuai , BENTHAUS Stn DW 1961; 23°21’S, 149°34’W; 19.XI.2002; 470-800 m depth; MNHN • 19 dd; Rimatara , BENTHAUS Stn DW 2020; 22°37’S, 152°49’W; 25.XI.2002; 920-930 m depth; MNHN • 5 dd; Rimatara , BENTHAUS Stn DW 2021; 22°37’S, 152°49’W; 25.XI.2002; 1200-1226 m depth; MNHN • 15 dd; Banc Arago, BENTHAUS Stn DW 1974; 23°24’S, 150°44’W; 20.XI.2002; 450-618 m depth; MNHN • 2 dd; South coast of Rurutu , BENTHAUS Stn DW 2010; 22°32’S, 151°21’W; 24.XI.2002; 520-950 m depth; MNHN • 2 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 • 6 dd; North coast of Rurutu , BENTHAUS Stn DW 1999; 22°25’S, 151°22’W; 23.XI.2002; 270-500 m depth; MNHN • 20 dd; Récif Neilson , BENTHAUS Stn DW 1925; 27°00’S, 146°05’W; 12.XI.2002; 560-790 m depth; MNHN • 3 dd; Récif Neilson , BENTHAUS Stn DW 1924; 27°01’S, 146°03’W; 12.XI.2002; 340-800 m depth; MNHN • 2 dd; Banc Président Thiers , BENTHAUS Stn DW 1937; 24°40’S, 145°56’W; 14.XI.2002; 469-500 m depth; MNHN • 1 dd; Banc Président Thiers , BENTHAUS Stn DW 1932; 24°41’S, 146°02’W; 14.XI.2002; 500-800 m depth; MNHN .

DISTRIBUTION AND SYMPATRY. — The species is known from the South Pacific Ocean, at the Tarava Seamounts (Mont Ari’i Moana, Mont Punu Taipu, Mont Honu, Mont ‘Otaha), Society Islands (Maupiti, Moorea, Huahine, Tahiti, Bora Bora, Raiatea, Btw Raiatea & Tahaa, Tahaa),Tuamotu (SW Kaukura, Kaukura,Tikehau, between Tikehau and Rangiroa) and Australes (Récif Neilson, Banc Président Thiers, Rimatara, Banc Arago, North coast of Rurutu, Tubuai, South coast of Rurutu, East coast of Rurutu, Banc Lotus, East of Rapa), with empty shells collected at 206-1250 m depth, and 16 specimens collected with the soft parts at 440-847 m depth in various locality (see Material examined) ( Fig. 25D ).

Benthonellania bouteti n. sp. is sympatric with Benthonella boucheti n. sp. at the Tarava Seamounts (Mont Honu and Mont ‘Otaha), Australes (Récif Neilson, Banc Président Thiers, Rimatara, Banc Arago, South coast of Rurutu, East coast of Rurutu, Tubuai), Tuamotu (between Tikehau and Rangiroa); with Benthonella basistriata n. sp. at the Tuamotu (Tikehau, Kaukura), Society Islands (Huahine, Moorea); with Benthonellania maestratii n. sp. at the Australes (Récif Neilson, South coast of Rurutu); with Benthonella communis 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, between Tikehau and Rangiroa, Tikehau), 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, Mont ‘Otaha, Mont Honu), Society Islands (Moorea), Tuamotu (SW Kaukura, Kaukura, Tikehau, between Tikehau and Rangiroa), Australes (Rimatara, East coast of Rurutu, South coast of Rurutu); with Benthonellania tuamotu n. sp. at the Tarava Seamounts (Mont ‘Otaha, Mont Panu Taipu), Tuamotu (SW Kaukura, Kaukura, between Tikehau and Rangiroa, Tikehau), Society Islands (Maupiti, Raiatea), Australes (Rimatara, South coast of Rurutu, Récif Neilson); with Benthonellania megan n. sp. from the Australes (Rimatara); with Benthonellania alis 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) ( Table 2).

ETYMOLOGY. — Named after Michel Boutet (Papara, Tahiti) for his indefatigable work of sorting the fine fractions of the material collected during the TARASOC cruise.

DESCRIPTION OF HOLOTYPE.

Shell ( Figs 14 A-D; 16A-E)

Large for the genus, height 3.45 mm, width 1.9 mm, height/ width ratio 1.816, rather solid, ovate-conical.

Protoconch ( Figs 14D ; 16 B-D)

Conical, multispiral, of 2.5 whorls, height 0.325 mm, nucleus diameter 0.075 mm, first half whorl diameter 0.15 mm, maximum diameter 0.40 mm; protoconch I with six threads with microtubercles in the interspaces ( Fig. 16D ); protoconch II with 5 spiral cordlets (the three adapical starting as zig-zag for 0.5 whorls) consisting of series of concatenated dart-like microtubercles ( Fig. 16B, C ). Protoconch-teleoconch boundary weak, flexuose, opisthocline.

Teleoconch

Of 4 slightly convex whorls, suture canaliculate, crowned by small tubercles at tip of axial ribs, highlighted by a spiral subsutural groove. Height last whorl 2.3 mm, height/height last whorl ratio 1.500. Axial sculpture of 15 slightly curved ribs, almost as broad as the interspaces, on the last whorl, gradually vanishing at the base. Last half whorl progressively devoid of axial ribs. Spiral sculpture absent. Microsculpture of growth striae, and subsutural spiral threadlets on interspaces between axial ribs ( Fig. 16E ). Umbilical chink present. Aperture pyriform, small, height 1.4 mm height/height aperture ratio 2.464, peristome continuous, varix absent, outer lip sharp, internally smooth (broken). Columella arcuate, simple.

Colour

Coloration of teleoconch very light pinkish-orange in fresh, live collected specimens, white in empty shells, protoconch orange.

Operculum and soft parts

Unknown.

VARIABILITY

Species not very variable (See Table 1 and Appendix 8). Less than a dozen specimens from Tahiti (DW3484 300-650 m), have the last whorl smooth or with very thin ribs. Maximum height 4.15 mm (from Rapa, 600-620 m). In some specimens, the tubercles at the tip of axial ribs of the last 0.25 whorl are smaller and progressively evanescent towards the aperture.

REMARKS

B. bouteti n. sp. differs from B. aequatorialis ( Thiele, 1925) n. comb. in its more robust tubercles at the subsutural crown; non-angled base (cfr juvenile shell of B. bouteti n. sp. in Fig. 14H with B. aequatorialis n. comb. in Fig. 11 A-D); higher protoconch 0.325 -0.375 mm and with five not equidistant spiral cordlets vs 0.275 with five equidistant cordlets in B. aequatorialis n. comb.

The juvenile specimen of an unidentified Benthonellania from southwestern Japan (Hasegawa: 152, fig. 5J) differs from juveniles of B. bouteti n. sp. in its more angled periphery, the weaker tubercled at the tips of axial ribs, and the faint spiral sculpture on the base (absent in Benthonellania bouteti n. sp.).

See under Benthonellania alis n. sp. for differences with this species.

Figures

FIG. 14. — Benthonellania bouteti n. sp.: A-D, holotype, height 3.45 mm, width 1.9 mm, Society Islands: TARASOC Stn DW3460, 660-680 m, 17°28’S, 149°50’W, MNHN-IM-2000-37678; E-G, specimen,height 4.15 mm,width 2.2 mm,Marquesas:BENTHAUS Stn DW1889,600-620 m, 27°37’S,144°16’W, MNHN;H, juvenile specimen, height 2.1 mm, Australes: BENTHAUS Stn DW1962, 470-800 m, 23°21’S, 149°33’W, MNHN. Scale bar: D, 0.25 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.