Parashiela soniae Amati & Giulio & Oliverio 2023, n. sp.
Creators: name: Amati, Bruno
name: Giulio, Andrea Di
name: Oliverio, Marco
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Rissoidae
Parashiela
Parashiela soniae

description: Parashiela soniae n. sp.
(Figs 32; 33; 51C; 53N; Tables 4; 5; 6)
urn:lsid:zoobank.org:act: A878ED1E-73A7-4421-A6B5-A47F77EA564F
TYPE MATERIAL. — Holotype. Marquesas • dd (height 1.17 mm, width 0.73 mm, Figs 32 A-C; 33; 53N); Nuku Hiva, Les 4 grottes, PAKAIHI I TE MOANA Stn MQ2-GR; 8°56’13”S, 140°7’15”W; 20-23 m; 07, 11-13, 29.I.2012; MNHN-IM-2000-38720.
Paratypes. Marquesas • 8 dd, 7 lv (Fig. 32 D-H); same locality data as holotype; MNHN-IM-2000-38721.
TYPE LOCALITY. — Marquesas: Nuku Hiva, Les 4 grottes, PAKAIHI I TE MOANA Stn MQ2-GR; 8°56’13”S, 140°7’15”W; 20- 23 m.
OTHER MATERIAL EXAMINED. — Marquesas • 3 dd, 4 lv; Tahuata PAKAIHI I TE MOANA Stn MQ12-M; 9°58’12”S, 139°7’33”W; 0-1 m; 15.I.2012; MNHN • 4 dd, 6 lv; Ua Pou, Hatu Iti cave, PAKAIHI I TE MOANA Stn MQ 27-GR; 9°23’41”S, 140°7’44”W; 5-22 m; 25.I.2012; MNHN • 1 dd; Nuku Hiva, Anao Bay; 8°49’40”S, 140°3’32”W; beached; coll. MB • 5 dd, 10 lv; Nuku Hiva, Matateteiko, PAKAIHI I TE MOANA Stn MQ 3-GR; 8°55’58”S, 140°13’33”W; 20-25 m; 8.I.2012; MNHN • 1 lv; Hatutu, Hatutaa Cave, PAKAIHI I TE MOANA Stn MQ 32-GR; 7°54’25”S, 140°33’57”W; 17-22 m; 27.I.2012; MNHN • 1 dd; Banc Hinakura, PAKAIHI I TE MOANA Stn MQ 31-ACH1 2; 7°55’58”S, 140°58’58”W; 120-300 m; 7.I.2012; MNHN.
DISTRIBUTION AND SYMPATRY. — Parashiela soniae n. sp. is at present known in the South Pacific Ocean from the Marquesas, with 28 live specimens collected (along with 23 empty shells) in 0-25 m, and an empty shell from Banc Hinakura in 120-300 m (Fig. 51C). No congener collected sympatrically.
ETYMOLOGY. — Named after Sonia Turchi, wife of one of the authors (ADG).
DIAGNOSIS. — Parashiela of small size for the genus (height c. 1 mm). Protoconch paucispiral with strong spiral cordlets. Protoconch-teleoconch boundary very marked and sinuous, with slight adapical detachment. Umbilical fissure evident. Teleoconch microsculpture of sparse dense microgranules.
DESCRIPTION OF HOLOTYPE
Shell (Figs 32 A-C; 33A; 53N)
Small for the genus, height 1.17 mm, width 0.73 mm, height/ width ratio 1.60, ovate-conical, rather robust, thick.
Protoconch (Fig. 33D, E)
Paucispiral, with nucleus moderately intorted, of 1.1 convex whorls, height 0.225 mm, nucleus diameter 0.075 mm, first half whorl diameter 0.175 mm, maximum diameter 0.250 mm. Six equidistant strong spiral cordlets made of tightly fused granules (less tightly on nucleus and near the protoconch-teleoconch boundary), the last abapical partially covered by the first teleoconch whorl; an additional adapical thinner cordlet of smaller and less tightly fused granules (Fig. 33D, E). Protoconch-teleoconch boundary very marked, sinuous, with slight adapical detachment (Fig. 33D, E).
Teleoconch
Of 2.75 convex whorls with weak double anglulation on the whorls. Axial sculpture on the last whorl of 14 orthocline and thin ribs, reaching the base and entering the umbilical fissure. Interspaces twice as wide as the axial ribs. Absence of macro spiral sculpture. Microsculpture of dense microgranules vaguely arranged in spiral series (Fig. 33B, C). Umbilical fissure evident. Aperture round-ovate, height 0.50 mm, height/ aperture height ratio 2.34; peristome duplicated; outer lip slightly prosocline, internally smooth, externally very thickened and with numerous growth striae; columellar lip slightly angled in the middle.
Colour
Colouration white-yellowish.
Operculum and soft parts
Operculum typical for the genus. Soft parts not examined.
VARIABILITY
Based on the examined material, the variability is low (see Table 5 and Appendix 14).
REMARKS
Parashiela soniae n. sp. is the first species of the genus formally described, with paucispiral protoconch, indicating non-planktotrophic larval development. However, an undescribed Parashiela with a protoconch paucispiral and spirally sculptured, from Madagascar (Indian Ocean, MNHN) was reported by Ponder (1985: 51); another species from Papua New Guinea, https://ingokurtz.jimdofree.com/mollusca-weichtiere/rissoidae/ also has a paucispiral protoconch; it differs from P. soniae n. sp. in the presence of an evident subsutural shoulder, absent or very narrow in P. soniae n. sp.; the prosocline axial ribs, orthocline or slightly prosocline in P. soniae n. sp.; the umbilical fissure very narrow or closed, clearly evident in P. soniae n. sp.
Parashiela expansilabrum n. sp. differs from P.soniae n. sp. in the multispiral protoconch (vs paucispiral in P. soniae n. sp.); the larger size (height 1.12-1.55 mm, mean 1.35 vs height 0.93-1.17 mm, mean 1.06 in P. soniae n. sp.); the more numerous axial ribs (18 vs 14 in P. soniae n. sp.); the broader base; the presence of a subsutural cord on the first whorls of teleoconch, absent in P. soniae n. sp.
Parashiela liddelliana (Hedley, 1907) differs from Parashiela soniae n. sp. in the multispiral protoconch (vs paucispiral in P. soniae n. sp.); the more numerous axial ribs (20 vs 14 in P. soniae n. sp.).
Parashiela rimatara n. sp. differs from P. soniae n. sp. in the multispiral protoconch (vs paucispiral in P. soniae n. sp.); the larger size (height 1.38-1.53 mm vs height 0.93-1.17 mm in P. soniae n. sp.); the thinner and more numerous axial ribs (26 vs 14 in P. soniae n. sp.); the subsutural cord on the first teleoconch whorls, absent in P. soniae n. sp.; the slightly wider umbilical fissure; the different teleoconch microsculpture, formed by threads arranged in dense spiral rows vs dense microgranules vaguely arranged in spiral series in P. soniae n. sp.
Parashiela rotundata n. sp. differs from P. soniae n. sp. in the multispiral protoconch (vs paucispiral in P. soniae n. sp.); the wider umbilical fissure; the microsculpture of teleoconch formed by groups of 3-4 thin threads separated by micro furrows vs dense microgranules vaguely arranged in spiral series in P. soniae n. sp.
description: Published as part of 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, pp. 803-892 in Zoosystema 45 (25) on pages 850-853, DOI: 10.5252/zoosystema2023v45a25, http://zenodo.org/record/10458066