Hyalorisia tosaensis ( Otuka, 1939 ),

Fassio, Giulia, Russini, Valeria, Buge, Barbara, Schiaparelli, Stefano, Modica, Maria Vittoria, Bouchet, Philippe & Oliverio, Ma, 2020, High cryptic diversity in the kleptoparasitic genus Hyalorisia Dall, 1889 (Littorinimorpha: Capulidae) with the description of nine new species from the Indo-West Pacific, Journal of Molluscan Studies (Rijksuniversiteit te Gent. Fakulteit van de Landbouwkundige en Toegepaste Biologische Wetenschappen) 86 (4), pp. 401-421: 414-415

publication ID

http://doi.org/ 10.1093/mollus/eyaa028

publication LSID




persistent identifier


treatment provided by


scientific name

Hyalorisia tosaensis ( Otuka, 1939 )


Hyalorisia tosaensis ( Otuka, 1939) 

MOTU-3 ( Figs 3CView Figure 3, 4CView Figure 4, 6EView Figure 6, 7C, LView Figure 7)

Capulus (Hyalorisia) tosaensis Otuka, 1939: 93  , 94 (Japanese text), 96, 97 (English text), figs 1–3 ( Bay of Tosa , Japan, 457 m; holotype, Seto Marine Biological Laboratory, Field Science Education and Research Center, Kyoto University, Japan)  .

Material examined: Holotype (only photographic image examined; Fig. 8View Figure 8 D–F)  and other material ( MNHN-IM-2007-34029, MNHN-IM-2007-34199, MNHN-IM-2007-34789, MNHN-IM-2007-34790, MNHN-IM-2007-34794, MNHN-IM-2013-58350, MNHN-IM-2013-58352, MNHN-IM-2013-58358, MNHN-IM-2013-58359, MNHN-IM-2013-59236, MNHN-IM-2013-59287, MNHN-IM-2013-59698 and AORI_YK2262). 

COI-based diagnosis: One diagnostic (autapomorphic) position in alignment: 50(C).

Shell (data for holotype shown within parentheses): Size medium to large for genus: length 7.68–19 (15.5) mm, width 5.2–15 (10.7) mm, height 2.8–5.44 (4.9) mm; thin, ellipsoidal or rounded, depressed; white shell surface with a smooth yellowish periostracum; anterior margin rounded or angled; protoconch of 0.9– 1 whorls, diameter of nucleus 0.09–0.25 mm; teleoconch smooth except for distinct commarginal growth ridges; apertural margin thin, interior glossy white; lamella from wide to narrow, width 0.6–1.8 (1.2) mm.

Soft parts (ethanol preserved): Head completely whitish or grey at the base; cephalic tentacles completely whitish or grey at the base or grey up to half of their length; pseudoproboscis whitish; mantle whitish or grey with whitish border; foot whitish or grey.

Radula: Taenioglossate, 2-1-R-1-2; marginal teeth sickle shaped; lateral teeth triangular, smooth or with few denticles on outer edge; rachidian tooth triangular with many or few denticles on both edges.

Host: Five specimens (MNHN-IM-2013-58350, MNHN-IM-2013-58352, MNHN-IM-2013-59236, MNHN-IM-2013-59287 and MNHN-IM-2013-59698) were found attached to each of five examples of P. sibogai  (MNHN-IM-2013-58349, MNHN-IM-2013- 58351, MNHN-IM-2013-59235, MNHN-IM-2013-59286 and MNHN-IM-2013-59286, respectively). One specimen ( MNHN-IM- 2013-58359) was attached to P. investigatoris  (MNHN-IM-2013-58396). The specimen collected in Japan ( AORI _YK2262) was also found attached to P. sibogai  . Five other specimens (MNHN-IM-2007-34029, MNHN-IM-2007-34789, MNHN-IM-2007-34790, MNHN-IM-2007-34794 and MNHN-IM-2013-58358) were found at stations where the only reported Propeamussium  was P. sibogai  . In the original description, Otuka also reported a specimen on Terebra pretiosa  from Okinosima, Koti Prefecture (now Okinoshima, Kochi Prefecture, Japan), but this record is questionable (see Remarks under genus Hyalorisia  ).

Distribution: So far known from Japan, the South China Sea, the Philippines, Papua New Guinea and the Solomon Islands, at depths of 278–1,045 m.

Remarks: In the original description, the protoconch is described as twisted to the left side. However, all the newly found specimens are dextrally coiled, and examination of the holotype has shown that the protoconch is actually dextral. Hyalorisia tosaensis  was found sympatric with H. melanesica  n. sp. (MOTU-8) in New Ireland, Papua New Guinea.














Hyalorisia tosaensis ( Otuka, 1939 )

Fassio, Giulia, Russini, Valeria, Buge, Barbara, Schiaparelli, Stefano, Modica, Maria Vittoria, Bouchet, Philippe & Oliverio, Ma 2020

Capulus (Hyalorisia) tosaensis

OTUKA, Y. 1939: 93