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 Author Amati, Bruno Largo Giuseppe Veratti, 37 / D, I- 00146 Roma (Italy) bruno _ amati @ yahoo. it amati@yahoo.it Author Giulio, Andrea Di Dipartimento di Scienze, LIME Lab, Università “ Roma Tre ”, Viale Marconi, 446, I- 00146 Roma (Italy) and NBFC, National Biodiversity Future Center, Palermo I- 90133 (Italy) andrea. digiulio @ uniroma 3. it Author Oliverio, Marco Dipartimento di Biologia e Biotecnologie ‘ Charles Darwin’, Sapienza Università di Roma, Viale dell’Università 32, I- 00185 Roma (Italy) marco. oliverio @ uniroma 1. it text Zoosystema 2023 2023-12-22 45 25 803 892 https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2023v45a25.pdf journal article 283961 10.5252/zoosystema2023v45a25 6247b5e8-e434-4ff4-a408-d8ee87c09da7 1638-9387 10458066 054D312B-C54B-459D-8A47-AC9CB681D7D4 Parashiela obesula n. sp. ( Figs 29 ; 51C ; 53K ; Tables 4 ; 5; 6) urn:lsid:zoobank.org:act: 8E9BA374-355A-4140-AA62-97657B1A62F5 TYPE MATERIAL . — Holotype . Australes • dd (height 1.32 mm , width 0.88 mm , Figs 29 ; 53K ); S of Rurutu , BENTHAUS Stn DW2010; 22°31’58”S , 151°20’59”W ; 520-950 m ; 24.XI.2002 ; MNHN-IM-2000-38714 . Paratypes . Australes • 2 dd; same locality data as holotype; MNHN- IM-2000-38715 . TYPE LOCALITY . — Australes: S of Rurutu; BENTHAUS Stn DW2010; 22°31’58”S , 151°20’59”W ; 520- 950 m . DISTRIBUTION AND SYMPATRY . — The species is at present known in the South Pacific Ocean from the Australes (Rurutu) ( Fig. 51C ), where it is sympatric with P. ambulata Laseron, 1956 and P. expansilabrum n. sp. ( Table 5 ). ETYMOLOGY . — From the Latin obesus, -a, -um meaning plump or fat, referring to the plump outline (- ula is a diminutive suffix). DIAGNOSIS . — Parashiela small for the genus, height 1.07-1.32 mm . Protoconch multispiral. Teleoconch with numerous, thin axial ribs, entering the umbilical fissure; convex whorls with no angles, macro spiral sculpture of only a thin suprasutural cordlets on the first whorl, vanishing on the second whorl. Microsculpture of dense spiral threads, some more marked. Peristome duplicated, with moderately thickened varix crossed by evident growth striae. DESCRIPTION OF HOLOTYPE Shell ( Figs 29 A-D; 53K) Small for the genus, height 1.32 mm , width 0.88 mm , height/ width ratio 1.50, rather robust, ovate-conical. Protoconch ( Fig. 29E, F ) Multispiral,dome-shaped, of1.35 whorls, height 0.200mm, nucleus diameter 0.063 mm , first half whorl diameter 0.137 mm , maximum diameter 0.250 mm ; protoconch I devoid of sculpture, protoconch II with only a thin spiral cordlet on lower third and microtubercles on the abapical area ( Fig. 29F ). Protoconch I-II boundary weak, sinuous. Protoconch-teleoconch boundary marked, with a sinusigera notch. Teleoconch Of 3.15 convex whorls, with a weak cordlet on the first whorl, fading and eventually disappearing on the second whorl. Axial sculpture on the last whorl of 37 thin, flexuose, slightly prosocline ribs, reaching the base and entering the umbilical fissure. Interspaces twice as wide as axial ribs, sculptured by numerous spiral threads, some thicker and more marked ( Fig. 29G ). Very narrow umbilical fissure. Aperture ovate-piriform height 0.58 mm , height/aperture height ratio 2.28; peristome continuous, duplicated; outer lip prosocline, slightly sinuous, smooth internally, externally expanded and very thickened, with numerous growth striae; columellar lip slightly angled medially. Colour Whitish colouration. Operculum and soft parts Unknown. VARIABILITY Only three specimens examined, all adults: no significant variation detected (see Table 5 and Appendix 11 ). REMARKS See under P. rimatara n. sp. and P. rotundata n. sp. for detailed comparisons.