A New Species of the Genus Cornisepta Mclean, 1988 (Gastropoda: Fissurellidae) from Japan

©Malacological Society of Japan

Short Notes

A New Species of the Genus Cornisepta McLean, 1988 (Gastropoda: Fissurellidae) from Japan

Mitsuo Chino 6-23-18-202 Arima, Miyamae-ku, Kawasaki, Kanagawa 216-0003, Japan; [email protected]

The fissurellid genus Cornisepta was established extremely high shell profile and overall resemblance by McLean (1988) to accommodate Fissurisepta to the type species. antarctica Egorova, 1972 (type species, by original designation) and 11 other small and high conical Cornisepta monsfuji n. sp. species. Only one representative, C. soyoae (Habe, (Figs. 1–6) 1951), has hitherto been recorded from Japanese waters. A new species, Cornisepta monsfuji n. sp., is Description: Shell small for genus, translucent, here added to this genus from southwestern Japan. thin and fragile, with highly elevated conical profile, The description and comparative remarks are given anterior slope convex; posterior slope concave; in the following lines. aperture oval, rim with regular projections. Apical whorl lost; foramen present at summit, sharpened at Abbreviations: MC — Mitsuo Chino collection, both anterior and posterior end, narrowed at centre; Kawasaki, Japan; MNHN — Muséum National septum thin, high, straight across, slightly concave d'Histoire Naturelle, Paris, France; MY — Masaumi posteriorly. Sculpture of 40–42 dense, raised, Yada collection, Ushibuka, Japan; NSMT — National sawtooth-shaped pustules running down towards Museum of Nature and Science, Japan. aperture, looking like stairs in lateral view, studded by acute notches, aligned in 24–28 curving rows, Taxonomy intercalated by 14–16 short interstitial rows and 38– 44 white lines, running towards and sharpened at Family Fissurellidae Fleming, 1822 aperture. Genus Cornisepta McLean, 1988 Type material: Holotype, NSMT-Mo 76806, SH (shell height) 2.2 mm, SL (shell length) 2.0 mm, Remarks: The genus Cornisepta was originally SW (shell width) 1.4 mm. Paratype 1, MNHN separated from the allied genus Fissurisepta 21208, SH 2.2 mm, SL 2.1 mm, SW 1.4 mm. Seguenza, 1863, mainly by the differences in radula Paratype 2, NSMT-Mo 76880, SH 2.2 mm, SL 2.2 characters, but it can also be distinguished from the mm, SW 1.5 mm. All specimens are empty shells latter in shell characters, specifically a higher from the type locality. profile, concave posterior slope and higher septum. Additional material examined: Paratype 3, MC, The shell of this genus is also characterized by the SH 2.0 mm, SL 1.9 mm, SW 1.3 mm. Specimen 1, sculpture of raised pustules aligned in curved rows. MC, SH 2.1 mm, SL 2.1 mm, SW 1.4 mm; specimen However, there is considerable interspecific 2, MY, SH 2.1 mm, SL 2.0 mm, SW 1.4 mm. All variability in the shell height/length ratio and from the type locality. morphology of the pustules (McLean & Geiger, Type locality: East China Sea 180 km southwest 1998; Table 1), and examination of the radula is off Kagoshima Prefecture, 30°18´N, 127°50´E, necessary to determine the precise generic position 240–270 m depth. All the specimens were obtained in some cases. Nevertheless, the present new together with numerous other small shells from a species, which is represented only by empty shells, clod of mud that was attached to the anchor of a is confidently assigned to this genus because of its tuna-fishing boat operated by Mr. Masaumi Yada. 64 VENUS 68 (1–2), 2009

Table 1. Comparison of conchological characters of Cornisepta spp. Species L (mm) H/L L/W Sculpture Distribution monsfuji n. sp. 2.0 1.0–1.1 1.4–1.5 white radial rows, and SW Japan; 240–270 m (holotype) curved rows of pustules acuminata Watson, 1883 5 0.83)–1.302) 1.143) dense pustule studded on Charlston, South Carolina, (=triangulata Dall, 1889) (holotype) 30 radial rows to Cozumel Is., Yucatan, and Virgin Is.; 290–700 m rostrata Seguenza, 1862 3.5–5.02),3) 0.92–1.432),3) 1.43–1.463) minute pustules 70 encircle, West France, northeatern (=elata Seguenza, 1862) 24 downward, scattered Atlantic to regularly on the surface Meditteranean; 1000– 2000 m festiva Crozier, 1966 5.133) 1.04–1.222),3) n.a. similar to fumarium with Three king’s Is., New scattered pustules, minute Zealand; 805 m growth lines, lack radial rows3) fumarium Hedley, 1911 2.153) 0.863)–0.802) 1.593) similar to acuminate Cape Willis, Australia; 180 m microphyma Dautzenberg 63) 0.833)–0.842) 1.53) similar to acuminate Azores; 861–1202 m & Fisher, 1896 onychoides Herbert & 4.53) 1.173) 1.403) pustules in curving rows South Africa; 250–430 m Kilburn, 1986 antarctica Egorova, 1972 7.03) 0.953) 1.433) pustular sculpture not Weddell and Antarctic apparent, pustules aligned Seas; 280–700 m in diagonal rows soyoae Habe,1951 3.6–4.21) 0.641)–0.672) 1.301) numerous bluntly prominent Sagami Bay, off Izu minute tubercles, evenly Peninsula, Suruga Bay distinguished granules, and south western Kyushu; pustules aligned in diagonal 120–270 m rows papillosa Seguenza, 1862 2.82) 0.56–0.722) n.a minute pustules in chains Lisbon, Portugal; 1000– 44–46 encircle the slope of 2000 m the shell, 14–16 downward scattered, regularly on the surface verene MacLean, 1988 1.6 0.813) 1.233) pustules appearing to be Axial Seamount, Juan de (holotype) linked in chains that Fuca ridge; 1530 m encircle the slope of the shell, the ridge interspaces deeply pitted levinae McLean, 1988 5.2 0.753) 1.271) thin, elongate, projecting Eastern pacific Rise; 1775 (holotype) in radial rows during early m growth and continuing in straight rows disorganized on sides pacifia Cowan, 1969 4.83) 0.753) 1.373) pustules in chains that Alaska, Vancouver, encircle the slope of the Oregon and southern shell California; 850 m 1) based on the data by Habe (1951); 2) based on the data by Ghisotti & Giannini (1983); 3) based on the data by McLean & Geiger (1998).

Range and habitat: Known only from the type aperture. Species of Cornisepta are highly variable locality, represented by empty shells. in height/length ratio, from 1.43 (C. rostrata) to Etymology: Cornisepta monsfuji n. sp. is named 0.56 (C. papillosa) (Table 1). The ratio is 1.0–1.1 in after snow covering Mt. Fuji, Japan’s highest and C. monsfuji n. sp., and is most similar to that of C. symbolic mountain. acuminata Watson, 1883 (around 1.10) from the Remarks: Present new species is characterized western Atlantic. However, C. acuminata differs by its small and highly conical shell with distinctly from the present new species in having dense serrated white radial riblets that reach to the pustules arranged in numerous curving rows Short Notes 65

Figs. 1–6. Cornisepta monsfuji n. sp. 1–4. Holotype, hight 2.2 mm, length 2.0 mm, width 1.4 mm, NSMT- Mo 76896. 5–6. Paratype 3, hight 2.0 mm, length 1.9 mm, MC. Figs. 7–10. Cornisepta soyoae Habe, 1951, height 3.1 mm, lentgh 4.2 mm, width 3.8 mm, south-west off Kagoshima Prefecture, East China Sea, 30°18´N, 127°50´E, 240–270 m deep. Scale: 1–3, 5–6 = 2 mm (at the same scale); 7–9 = 2 mm; 4, 10 = 1 mm.

(Farfante, 1947: pl. 64, figs. 1–3) . The sole other from the present new species, however, not only in Japanese species, C. soyoae Habe, 1951 (Figs. 5–7), the shell profile (3.6–4.2 in height/length ratio in C. occurs sympatrically with C. monsfuji. This soyoae) but also in the sculpture (Figs. 1–8; Table represents a range extension for C. soyoae westward 1). to the East China Sea. It is readily distinguishable 66 VENUS 68 (1–2), 2009

Acknowledgments: I am grateful to Mr. Masaumi Yada of Ushibuka, Kumamoto Prefecture, for 鹿児島県南西沖より採集された providing specimens for study, Dr. Takashi Okutani, フジスカシガイ属の 1新種 Japan Agency for Marine-Earth Science and Technology, Dr. Kazunori Hasegawa (NSMT) and 知野光雄 Dr. Takenori Sasaki of the University of Tokyo for providing references and correcting the manuscript, and Dr. Paolo Crovato, President Societa Italiana di McLean & Geiger (1988) は Fissurisepta Seguenza, Malacologia for providing references. Dr. Hasegawa 1862に含まれていた種類のうち，特殊化した歯舌 also took the photographs and prepared the plate. と高い殻高を持つ種に対し新属 Corniseptaフジスカシガイ属（新称）を設け，この中に 2新種を含 References む 12種を含めた。本属には，本邦産として C. Farfante, I. P. 1947. The genera Zeidora, Nesta, soyoae（ Habe, 1951）フジスカシガイも含められて Emarginula, Rimula and Puncturella in the いるが，今般，鹿児島県南西部より得られた標本 western Atlantic. Johnsonia 2: 93–148. により，さらに 1新種を認めたので記載する。 Ghisotti, F. & Gianini, F. 1983. Considerazioni sul genere Fissurisepta. Bollettino Malacologico Cornisepta monsfuji n. sp. ユキフリスカシガイ 9: 25–36. （和名新称） Habe, T. 1951. Fissurellidae in Japan. Illustrated 同属種の中ではやや小型。著しく高円錘形，前 Catalogue of the Shells of Japan 17: 109–120, pl. 17. 部斜面は膨らみ，後部斜面は凹み，殻口底面は楕 McLean, J. H. & Geiger, D. L. 1998. New genera 円形。殻表面には殻頂から殻底に向け約 24～28条， and species having the Fissurisepta shell form, 殻底付近では肋間に短い 14～16条の規則的な放射 with a generic-level phylogeneric analysis (Gastropoda: Fissurellidae). Contributions in 状白線放射肋あり，殻底周縁でやや突出する。白 Science, Natural History Museum of Los 線を構成する顆粒は 40～42のギザギザの棘を生じ Angeles County (475): 1–32. る。放射条線は僅かに認められるが不鮮明。 (Accepted June 17, 2009) 比較：フジスカシガイに比べ殻高が著しく高く，殻高，殻長とも小型。同種では殻表面に無数の細かい顆粒点列が斜行し，対角線が交差するように規則的に並ぶのに対し，本種では殻頂から殻底に向け放射状白線の縦肋が走ることで異なる。種名は富士山，和名は富士山の尖った頂上から雪渓が降下する様を想定した。タイプ標本：ホロタイプ， NSMT-Mo 76806，殻高 2.2 mm，殻長 2.0 mm。タイプ産地：鹿児島県坊岬沖 180 km，戦艦大和沈没地点近辺水深 350 m。漁船の抜錨に付着した砂泥塊より採集。生貝は得られていない。フジスカシガイが同所的に得られ，同種の分布域も相模湾，駿河湾から九州南西沖に拡大した。