Benthonella basistriata Amati, Giulio, and Oliverio 2022
- Dataset
- Deep-water Rissoidae of the genera Benthonella Dall, 1889 and Benthonellania Lozouet, 1990 (Gastropoda, Caenogastropoda, Rissooidea) from French Polynesia
- Rank
- SPECIES
- Published in
- 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): 335-389, DOI: 10.5252/zoosystema2022v44a12
Classification
- kingdom
- Animalia
- phylum
- Mollusca
- class
- Gastropoda
- order
- Littorinimorpha
- family
- Rissoidae
- genus
- Benthonella
- species
- Benthonella basistriata
description
(Figs 3 A-H; 5 F, G; 25 B; 26 B; Tables 1; 2) urn: lsid: zoobank. org: act: 98730 F 8 F-ECFB- 479 D-BE 22 - 82 E 2 DB 64 DF 15
description
DESCRIPTION OF HOLOTYPE Shell (Figs 3 A-D; 5 F, G) Small for the genus, height 2.0 mm, width 1.3 mm, height / width ratio 1.538, rather solid, ovate-conical. Protoconch (Figs 3 D; 5 G) Multispiral, dome-shaped, of 2.5 whorls, height 0.3375 mm, nucleus diameter 0.075 mm, first half whorl diameter 0.125 mm, maximum diameter 0.375 mm; protoconch I with 5 spiral threads, interspaces covered by microtubercles (Fig. 5 G); protoconch II with 2 fine spiral cordlets, with irregularly set microtubercles on the subsutural area (Fig. 5 G). Protoconchteleoconch boundary indistinct. Teleoconch Of 3.25 whorls, the first 2 flat, the others slightly convex, sutures canaliculate, crowned by small tubercles on tip of axial ribs. Height last whorl 1.3 mm, height / height last whorl ratio 1.538. Axial sculpture on the last whorl of 18 curved, opisthocline ribs, almost as broad as the interspaces, gradually vanishing on the base. Spiral sculpture of 6 weak, fine cordlets, only on the base of last whorl (abapical last barely visible); one suprasutural cordlet visible on upper whorls. Microsculpture of only growth striae. Umbilical chink absent. Aperture pyriform, small, height 0.8 mm. height / height aperture ratio 2.424, peristome continuous, varix large; outer lip (broken) prosocline, internally smooth, sharp. Columella angled, simple. Colour Coloration of teleoconch white, outer lip orange faded, darker than subsutural zone, protoconch whitish-orange. Operculum and soft parts Unknown. VARIABILITY Species not very variable (See Table 1 and Appendix 2). Maximum height 2.60 mm, width 1.65 mm (from Tuamotu: Tikehau 889 m). The number of axial ribs on the last whorl can vary from 14 to 20.
discussion
REMARKS Benthonella basistriata n. sp. is similar in the general shape to the fossil Benthonella lutetiana Lozouet, 2014 and Benthonella priabonica Lozouet, 2014, both from the Eocene of France (see Lozouet 2014: 24 - 25, 28; 2 I-K; 5 A-E and 2014: 24 - 25, 29, figs 2 L-N; 6 A-H, respectively). They are essentially distinguished by the different sculpture of the protoconch II: B. lutetiana and B. priabonica have two thin spiral cordlets, one abapical close to the suture, the other adapical closer to the suture in B. lutetiana; B. basistriata n. sp. has two broader spiral cordlets, the adapical farther from the suture, and microgranules on the subsutural area (apparently lacking in the fossil species). Benthonella olangoensis (Poppe, Tagaro & Stahlschmidt, 2015) has a similar outline. It differs in the fewer spiral cordlets (2 - 3 vs 5 - 6 in B. basistriata n. sp.: based on the photos of the type material, since in the original description, this sculpture and the precise number of cordlets are not reported). B. basistriata n. sp. also resembles Benthonellania agastachys Bouchet & Warén, 1993. Benthonella basistriata n. sp. has a spiral sculpture of 6 basal cords vs c. 10 basal cords in an adult specimen of Benthonellania agastachys figured by Ortega & Gofas (2019: 525, figs 8 A-D; the holotype with 4 - 5 cords is a juvenile); the umbilical chink absent vs present in B. agastachys; the protoconch multispiral, with two fine spiral cordlets and subsutural microtubercles vs paucispiral, lacking spiral cordlets, densely granulated, with granules tending to be spirally arranged in B. agastachys (see Bouchet & Warén 1993: 682, figs 1584, 1592 - 1593). See under Benthonellania hertzogi (Thiele, 1925) n. comb. and Benthonellania thielei n. sp. for deatailed comparisons.
distribution
DISTRIBUTION AND SYMPATRY. — The species is known from the South Pacific Ocean in the Tuamotu (Tikehau, Kaukura) and Society Islands (Huahine, Moorea), with empty shells collected in 485 - 889 m depth (Fig. 25 B). Benthonella basistriata n. sp. is sympatric with Benthonella communis n. sp. at the Society Islands (Huahine, Moorea), Tuamotu (Kaukura); with Benthonellania bouteti n. sp. at the Tuamotu (Kaukura, Tikehau), Society Islands (Huahine, Moorea); with Benthonellania tarava n. sp. at the Tuamotu (Kaukura, Tikehau), Society Islands (Moorea); with Benthonellania tuamotu n. sp. at the Tuamotu (Kaukura, Tikehau) (Table 2).
etymology
ETYMOLOGY. — For the particularly marked basal sculpture, from the Latin basis – base, striata – striated.
materials_examined
TYPE MATERIAL. — Holotype. Tuamotu. • dd (height 2.0 mm, width 1.3 mm, Figs 8 A-D; 10 F, G); Tikehau, TARASOC Stn DW 3389; 14 ° 55 ’ S, 148 ° 15 ’ W; 889 m depth; MNHN-IM- 2000 - 37668. Paratypes • 2 dd; same locality data as holotype; MNHN- IM- 2000 - 37669. TYPE LOCALITY. — Tuamotu, Tikehau, TARASOC Stn DW 3389, 14 ° 55 ’ S, 148 ° 15 ’ W, 889 m depth. OTHER MATERIAL EXAMINED. — Society Islands • 1 dd; Huahine, TARASOC Stn DW 3425; 16 ° 43 ’ S, 151 ° 03 ’ W; 557 m; 14. X. 2009; MNHN • 2 dd; Huahine, TARASOC Stn DW 3435; 16 ° 41 ’ S, 151 ° 02 ’ W; 500 - 612 m; 15. X. 2009; MNHN • 1 dd; Moorea, TARASOC Stn DW 3459; 17 ° 28 ’ S, 149 ° 48 ’ W; 485 - 560 m; 19. X. 2009 • 3 dd; Moorea, TARASOC Stn DW 3481; 17 ° 29 ’ S, 149 ° 45 ’ W; 610 m; 22. X. 2009 • 1 dd; Moorea, TARASOC Stn DW 3474; 17 ° 28 ’ S, 149 ° 50 ’ W; 720 m; 21. X. 2009; MNHN. Tuamotu • 15 dd; Kaukura, TARASOC Stn DW 3373; 15 ° 41 ’ S, 146 ° 54 ’ W; 507 - 607 m; 4. X. 2009; MNHN.