Semisulcospira niponica
Creators: name: Sawada, Naoto
name: Fuke, Yusuke
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Semisulcospiridae
Semisulcospira
Semisulcospira niponica

description: Semisulcospira niponica (Smith, 1876)
(table 2, supplementary table S1; figs. 8A–K, Q –AN, 12A–G)
Melania niponica Smith, 1876: 123–124 (part); Martens, 1877: 116 (exact taxonomic account uncertain; TAU); Brot, 1877: 338–339, pl. 34, figs 10 (part); Kobelt, 1879: 131, pl. 19, figs 5–7, 10 –14 (part); Pilsbry, 1902: 119; Iwakawa, 1919: 82 (part; TAU); Annandale, 1916: 45, pl. 3, fig. 3A (part).
Melania biwae Kobelt, 1879: 132–133, pl. 19, fig. 9; Pilsbry, 1902: 120.
Melania (Melanoides) niponica – Nevill, 1884: 264 (TAU).
Melania (Semisulcospira) niponica – Boettger, 1886: 8.
Melania nipponica – De Elera, 1896: 335.
Semisulcospira niponica – Kuroda, 1929: 186, 189, pl. 5, figs 32–33 (part); Fukuoka, 1933: 114, 117, fig. 5; Kajiyama & Habe, 1961: 167; Kuroda, 1962: 86 (part; TAU); Kuroda & Habe, 1965: 57 (part); Habe & Kosuge, 1967: 28, pl. 11, fig. 22 (part); Davis, 1969: 243–246, pl. 4, figs 1–3; Watanabe, 1984: fig. 3b–d, f–h (part); Watanabe, 1989: 11–13, 47, figs 10, 27, 28 (part); Köhler, 2016: fig. 4O, P.
Melanoides (Semisulcospira) niponicus – Mori, 1936: 229–230; Mori, 1937: 37–38, fig. 1.
Hua? niponica – Kira, 1954: 127, pl. 63, fig. 1.
Biwamelania niponica – Habe, 1978: 94; Nishino & Tanida, 2018: 56, 251 (part).
Biwakomelania niponica – Habe, 1984: 305.
Semisulcospira (Biwamelania) niponica – Matsuoka, 1985: 190; Nishino, 1991: 9–10, unnumbered figures (part); Urabe, 2007: 80, fig. 1A; Kihira, et al., 2009: 24–25, unnumbered figure (part); Miura et al., 2019: fig. S1f; Nishino, 2021: 621.
Semisulcospira nipponica – Higo & Goto, 1993: 97; Goto & Poppe, 1996: 204.
Semisulcospira (Biwamelania) niponica (nodose type) – Watanabe & Nishino, 1995: 17–18, fig. 5b (part).
Material examined: Voucher specimens: Lectotype: NHM 1875.11.24.11/1, adult shell, sex undetermined, collected from Lake Biwa in central Honshu Island, Japan in 1875 by Charles Wycliffe Goodwin. Paralectotypes: NHM 1875.11.24.11/2, 1875.11.24.11/3, 2 adult shells, sex undetermined, collected with lectotype. SMF 29151, 1 adult shell, sex undetermined, collected from Lake Biwa in 1874 by Johannes Justus Rein. KUZ Z3959 14 males, KUZ Z3766, 15 females, collected from Otsu Port on 23 June 2020 by Naoto Sawada.
Additional materials:KUZ Z4091, 15 females, KUZ Z4092, 1 male, collected from Oura Port on 28 November 2021; KUZ Z4093,15 females, KUZ Z4094, 15 males, collected from Nagahama Port on 28 November 2021; KUZ Z4095, 12 females, KUZ Z4096, 5 males, collected from Iso on 24 January 2021; KUZ Z4097, 8 females, collected from Kitakomatsu Port on 28 November 2021; KUZ Z4098, 1male, collected from Kitakomatsu Beach on 9 January 2022; KUZ Z4099, 15 females, KUZ Z4100, 10 males, collected from Katata Port on 28 November 2021; KUZ Z4101, 15 females, KUZ Z4102, 10 males, collected from Nango on 28 November 2021.
Amended diagnosis: Viviparous semisulcospirid. Adult shell medium sized [SH 27.7 ± 2.9 (mean ± SD) (female), 23.8 ± 2.1 (male) mm; BWL 17.3 ± 1.6, 14.8 ± 1.3 mm], nearly triangular (SA 23.2 ± 2.7, 22.7 ± 2.6 degrees); color in black or brackish brown background; outer lip of aperture hardly swell (ASL 0.06 ± 0.04, 0.09 ± 0.04 mm); 3.3 ± 1.0, 3.2 ± 0.9 BCN; 13.1 ± 2.1, 11.8 ± 1.9 distinct, longitudinal ribs slightly to moderately nodulated on penultimate whorl; 4.2 ± 0.8, 3.9 ± 0.8 SCN; 1.6 ± 0.1, 1.7 ± 0.1 ASR; 2.9 ± 0.3, 3.0 ± 0.3 WER. Embryonic shell medium sized, with distinct nodes on surface; color in black background or beige background with 3 brown or black bands.
Lectotype designation: One syntype, NHM 1875.11.24.11/1 (fig. 8A–C), was chosen as the lectotype for S. niponica in this study because the specimen possesses 15 longitudinal ribs and 3 spiral cords on the body whorl, which correspond to the values in the original description. The other two syntypes, NHM 1875.11.24.11/2 (fig. 8D) and NHM 1875.11.24.11/3 (fig. 8E) have 6 or 7 spiral cords on the body whorls and were described as a variation of the species (Smith, 1876).
Description: Lectotype, NHM 1875.11.24.11/1 (fig. 8A–C): AH 9.1 mm, AL 9.3 mm, ASR 1.62, AW 5.7 mm, BCN 2, BWL 15.4 mm, NL 0.04 mm; PWL 5.5 mm, RN 15, SA 22.1 degrees, SCN 3, SH 22.1 mm, SW 9.9 mm, TWL 4.6 mm, WN 3.25. Shell nearly triangular; suture hardly undulating; whorl sides slightly convex; outer lip of aperture hardly swell; longitudinal ribs distinct, almost straight, oblique, prominently nodulated in penultimate to body whorl; apex of shell eroded; shell color partly faded, colored brown in body to penultimate whorl, blackish brown in remaining whorls, without color band; without operculum.
Paralectotypes: NHM 1875.11.24.11/2 (fig. 8D): AH 5.9 mm, AL 5.2 mm, BCN 3, BWL 10.3 mm, FWL 3.0 mm, NL 0 mm, PWL 4.1 mm, SA 11.3 degrees, SCN 7, SH 17.0 mm, SW 6.1 mm, TWL 3.6 mm, WER 1.97; WN 3.25; shell greatly elongated; suture moderately undulating; whorl sides moderately convex; swell of outer lip of aperture absent; longitudinal ribs indistinct, moderately curved, oblique, crossed by prominent spiral cords in penultimate to body whorl; apex of shell eroded; shell color partly faded, colored blackish brown background; aperture chipped; without operculum. NHM 1875.11.24.11/3 (fig. 8E): AH 6.3 mm, AL 6.1 mm, ASR 1.62, AW 3.8 mm, BCN 3, BWL 10.9 mm, FWL 2.5 mm; PWL 4.2 mm, SA 17.7 degrees, SCN 6, SH 17.2 mm, SW 6.8 mm, TWL 3.2 mm, WER 2.49; WN 3.25; shell elongated; suture moderately undulating; whorl sides slightly convex; swell of outer lip of aperture absent; sculpture distinct, slightly curved, vertical, ribbed longitudinally in penultimate whorl, ribs partly nodulated in body whorl; apex of shell eroded; shell color partly faded, colored beige background; aperture slightly chipped; without operculum.
Variation: Adult shells (fig. 8G–I, Q, T, X, AA, AD, AF, AI, AL): Holotype of S. biwae, SMF 291511: AH 9.6 mm, AL 9.9 mm, ASR 1.53, AW 6.4 mm, BCN 3, BWL 15.7 mm, PWL 5.3 mm, RN 11, SA 25.6 degrees, SCN 3, SH 21.6 mm, SW 10.9 mm, TWL 4.1 mm, WN 3.25; shell nearly triangular; suture hardly undulating; whorl sides moderately convex; outer lip of aperture slightly swell; longitudinal ribs distinct, almost straight to slightly curved, prominently nodulated in penultimate to body whorl; apex
of shell largely eroded; shell colored beige in lower half of body whorl, brown in remaining whorls, without color band; without operculum.
Newly collected specimens: Measurements and counts shown in table 2 and supplementary table S1. Shell near thick to slightly elongated triangular; suture hardly to slightly undulating; whorl sides slightly convex; outer lip of aperture hardly to slightly swell; longitudinal ribs on penultimate whorl distinct, almost straight to slightly curved, oblique, slightly to prominently nodulated by spiral cords, rarely spiral cords alone on penultimate whorl; sculptures often ribbed on upper whorls, granulated in lower whorls; shell colored black or brackish brown in
Downloaded from Brill.com 08/29/2023 02:12:56AM
via free access background, sometimes several indistinct brown band on lower part of each whorl.
Operculum (fig. 8R, U, Y, AB, AE, AG, AJ, AM): 5.5–8.5 mm in long diameter; nearly egg-shaped subcircular, paucispiral, comprising around 3 whorls; nucleus subcentral.
Embryonic shells (fig. 8S, W, Z, AC, AH, AK, AN): Measurements and counts shown in table 2 and supplementary table S1. Shell globose; suture prominently depressed by discrepancy in adjacent whorls; nodes remarkable, on central part of whorls; keels weak, on lower part of whorls; shell colored black background or beige background with 3 brown or black bands on upper and lower part of each whorl and on basal part of shell.
Radulae (fig. 12A–G): Taenioglossa consisting of rachidian in single, lateral teeth, interior and exterior marginal teeth in double row. Rachidian roughly triangular, with large central denticle and 2–3 minor pointed triangular cusps on each side. Lateral teeth with large central denticle, 2–3 inner and outer pointed cusps. Central denticle tip of rachidian and lateral teeth mostly flat, rarely pointed; central denticle of rachidian approximately regular triangular, about 2.5 to 6.0 times longer than other triangular cusps; central denticle of lateral teeth irregular triangular, about 1.5 to 4.0 times longer than other triangular cusps. Interior and exterior marginal teeth spoon-shaped, with 4–6 rounded denticles.
Reproductive organs: Female: Long narrow oviduct, entering near seminal receptacle with long protrusions. Ventral edge of spermatophore bursa with curved sperm gutter, extending toward mantle cavity. Brood pouch on dorsal side of spermatophore bursa, inflated dorsally, separated into many cells, including eggs and embryos; eggs and embryos radially developing from base of brood pouch near seminal receptacle and embryos in anterior or dorsal cells more developed.
Male: Gonad consisting of testes, vas deferens, and prostate without penis. Posterior ventral part of inflated prostate with deep groove, forming U-shape in transverse section. Anterior prostate narrowly opening to mantle cavity.
Distribution and ecology: Semisulcospira niponica is one of the most widespread species in Lake Biwa (Watanabe & Nishino, 1995; fig. 5b, S. (B.) niponica nodose). The species was discovered in eight localities in this study and is most widely distributed in the S. niponica -group (fig. 1). Semisulcospira niponica mainly inhabits coastal shallow rocky areas and on concrete blocks around harbours at 0–1 m, while it is rarely found on small rocks in shallow sandy areas (e.g., Kitakomatsu Beach and Iso). This species was found with S. watanabei at Kitakomatsu Port and occurred with other Lake Biwa species: S. habei at Oura Port, Nagahama Port, Kitakomatsu Beach, Otsu Port; S. dilatata Watanabe & Nishino, 1995 at Iso; S. decipiens at Otsu Port.
Remarks: One of paralectotypes of S. niponica (NHM 1875.11.24.11/2) was identified as S. decipiens by the small SA and shell surface with longitudinal ribs and spiral cords following Davis (1969) and Watanabe and Nishino (1995). The other paralectotype (NHM 1875.11.24.11/3) was similar to S. habei in the middle SA and had a moderately convex shell with shell surface sculptures. A note “+ v. minor ” was added to the label of the type lot (fig. 8F). As Urabe (2007) discussed the name-bearing types of S. niponica cannot be a type specimen of S. niponica var. minor (Brot, 1883). The taxonomic account of the latter species was established based on specimens collected from Taiwan. The three species included in the type lot of S. niponica are indigenous to Lake Biwa.
Semisulcospira niponica resembles S. watanabei sp. nov. in shell outline shape and outer lip of the aperture, which hardly undulates. However, the former species tends to possess granulated longitudinal ribs on the shell surface, and this tendency is stronger where both species coexist (fig. 7). Semisulcospira niponica also represents a greater value of BWL, RN, SA, and SHE than S. watanabei sp. nov. Semisulcospira niponica can be discriminated from other congeners with its blackish triangular adult shell and few longitudinal ribs and spiral cords, and globose embryonic shells with several brown bands (supplementary fig. S1).
description: Published as part of Sawada, Naoto & Fuke, Yusuke, 2023, Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae), pp. 1-37 in Contributions to Zoology 92 (1) on pages 20-24, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/8349612