638 research outputs found
FIGURE 6 in Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae)
No full textFIGURE 6 Map of Lake Biwa indicating geographical variation in the frequency of sculpture types in the adult females of five Semisulcospira species. Colours of locality names correspond to the colour coding in fig. 1Published 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 page 13, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
FIGURE 4 in Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae)
No full textFIGURE 4 Results of ADMIXTURE analysis based on 738 SNP s conducted for five Semisulcospira species. Bar colours of the species in K = 5 correspond to the colour coding in fig. 3Published 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 page 9, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
FIGURE 7 in Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae)
No full textFIGURE 7 Results of Random Forest analyses conducted for five Semisulcospira species. Euclidean distances generated from proximities among individuals are plotted. A, Female. B, MalePublished 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 page 16, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
FIGURE 3 in Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae)
No full textFIGURE 3 Results of principal components analysis based on 738 SNP s conducted for five Semisulcospira species. A, Principal component (PC) 1 vs PC 2. B, PC2 vs PC3. C, PC 3 vs PC4. D, PC4 vs PC5Published 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 page 8, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
FIGURE 1 in Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae)
No full textFIGURE 1 Map of Lake Biwa (A) and Oura Bay (B) showing 15 sampling localities: blue, Semisulcospira niponica; green, S. fuscata; purple, S. watanabei sp. nov.; red, S. nakanoi sp. nov.; orange, S. salebrosa sp. nov; black, putative hybrid between S. fuscata and S. watanabei sp. nov.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 page 3, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
FIGURE 11 in Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae)
No full textFIGURE 11 Shells of Semisulcospira salebrosa sp. nov. A–G, Holotype, KUZ Z4131. H–J, Paratype, KUZ Z4133. K–L, Paratype, KUZ Z4135. M–O, Specimen from Take-shima Island, KUZ Z4138. A–C, H, K, M, Adult shell. A–C, H, M, Female. K, Male. D, I, L, N, Operculum. E–G, J, O, Embryonic shell. Scale bars: 10 mm (A–D, H–I, K–L, M–N), 1 mm (E–G, J, O). All specimens were treated with 3% sodium hypochloritePublished 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 page 22, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
FIGURE 10 in Diversification in ancient Lake Biwa: integrative taxonomy reveals overlooked species diversity of the Japanese freshwater snail genus Semisulcospira (Mollusca: Semisulcospiridae)
No full textFIGURE 10 Shells of Semisulcospira nakanoi sp. nov. A–G, Holotype, KUZ Z4122. H–J, Paratype, KUZ Z4125. K–L, Paratype, KUZ Z4126. M–Q, Specimens from Onoe Port, KUZ Z4129, Z4130. A–C, H, K, M, P, Adult shell. A–C, H, M, Female. K, P, Male. D, I, L, N, Q, Operculum. E–G, J, O, Embryonic shell. Scale bars: 10 mm (A–D, H–I, K–L, M–N, P–Q), 1 mm (E–G, J, O). All specimens were treated with 3% sodium hypochloritePublished 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 page 21, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
Semisulcospira salebrosa Sawada 2023, sp. nov.
No full textSemisulcospira salebrosa Sawada sp. nov. [New Japanese name: Konpeito-kawanina] (table 2, supplementary table S2; figs 11, 12O, P) urn:lsid:zoobank.org:act: 003C4CE6-596C-4F67-8C30-E5A51DC88B37 Semisulcospira niponica – Watanabe, 1984: fig. 3c–d, g–h. Semisulcospira (Biwamelania) niponica – Nishino, 1991: 9–10, unnumbered figures (part); Kihira et al., 2009: 24–25, unnumbered figure (part); Miura et al., 2019: fig. S1d, e. Biwamelania nipponica – Minato, 1991: 79, unnumbered figure. Semisulcospira (Biwamelania) niponica (biwae type) – Watanabe & Nishino, 1995: 17–18, fig. 5b (part). Biwamelania niponica – Nishino & Tanida, 2018: 56, 251, unnumbered figure (part). Material examined: Holotype:KUZ Z4131, adult female with embryonic shells treated with sodium hypochlorite, collected from a depth of 3.0 m of Lake Biwa at Shiraishi-jima Island, Takashima City, Shiga Prefecture, Japan, on 9 September 2020 by first author. Paratypes: KUZ Z4132–Z4135, 3 adult females, 1 adult male, collected with holotype. Additional materials: KUZ Z4136, 11 females, KUZ Z4137, 3 males, collected with type specimens; KUZ Z4138, 15 females, KUZ Z4139, 10 males, collected from Take-shima Island on 25 July 2021. Etymology: The specific name is after prominent granulated longitudinal ribs on adult shells of the new species. Diagnosis: Viviparous semisulcospirid. Adult shell large (SH 35.7 ± 2.0, 27.6 ± 4.9 mm, BWL 21.9 ± 1.5, 16.6 ± 2.8 mm), nearly triangular (SA 21.2 ± 2.5, 21.5 ± 4.6 degrees); color in black background; outer lip of aperture prominently swell (ASL 0.44 ± 0.12, 0.33 ± 0.14 mm); 2.5 ± 0.7, 2.3 ± 0.5 BCN; ribs relatively few, prominently nodulated on penultimate whorl (RN 11.1 ± 1.6, 10.6 ± 1.4); 3.4 ± 0.7, 3.2 ± 0.4 SCN; 1.6 ± 0.1, 1.6 ± 0.1 ASR; 3.0 ± 0.3, 3.2 ± 0.6 WER. Embryonic shell medium sized, with distinct nodes on surface; color in beige background with 3–4 brown or black bands. Description of holotype: Adult shell (fig. 11A–C): AH 14.2 mm, AL 14.5 mm, ASR 1.63, AW 8.9 mm, BCN 3, BWL 23.0 mm, FWL 5.3 mm; NL 0.42 mm; PWL 8.2 mm, RN 9, SA 18.5 degrees, SCN 3, SH 39.4 mm, SW 15.7 mm, TWL 6.6 mm, WER 2.71; WN 4.75; shell near slightly elongated triangular; suture hardly undulating; whorl sides slightly convex; outer lip of aperture swell prominently; longitudinal ribs slightly curved, straight, nodulated prominently in upper to body whorl; apex of shell eroded; shell colored black background without color band. Operculum (fig. 11D): 8.8 mm in long diameter; nearly egg-shaped subcircular, paucispiral, comprising around 3 whorls; nucleus subcentral. Embryonic shells (fig. 11E–G): EN 30, RNE 12, SHE 2.7 mm, SWE 2.5 mm, WNE 2.5; shell globose; suture prominently undulating; remarkable nodes present on central part of whorls, keels absent on lower part of whorls; shell colored beige background with 3 black bands on upper and/or lower part of each whorl and/or on basal part of shell. Radula: 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 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 3.0 times longer than other triangular cusps; central denticle of lateral teeth irregular triangular, about 3.5 times longer than other triangular cusps. Interior and exterior marginal teeth spoon-shaped with 4–5 rounded denticles. Reproductive organ: 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. Variation: Adult shells (fig. 11M): Measurements and counts shown in table 2 and supplementary table S2. Shell nearly triangular to slightly elongated; suture slightly to moderately undulating; whorl sides slightly to moderately convex; sculptures prominent, almost straight to slightly curved, vertical to slightly oblique, prominently nodulated, rarely ribbed on upper whorls; shell colored black to brackish brown background with or without several color bands on upper, middle, and lower part of each whorl and basal part of shell; surface of shells covered with thin algae layer before treatment. Operculums (fig. 11I, L, N): 8.8–11.1 mm in long diameter. Embryonic shells (fig.11J, O):Measurements and counts shown in table 2 and supplementary table S2. Suture slightly or prominently undulating; distinct keels present or absent on lower part of whorls; shell colored beige background with 3 brown or black bands on upper and/or lower part of each whorl and/or on basal part of shell. Radulae (fig. 12O, P): 2–4 minor pointed triangular cusps on each side of rachidian; lateral teeth with 1–4 inner and outer pointed cusps; central denticle of rachidian about 2.5 to 5.0 times longer than other triangular cusps; central denticle of lateral teeth about 1.5 to 3.0 times longer than other triangular cusps. Reproductive organs: 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: The known distribution of S. salebrosa sp. nov. is restricted to Shiraishi-jima Island and Take-shima Island in Lake Biwa (fig. 1). The new species inhabits the wharf and rocky bottom of the islands. Semisulcospira salebrosa sp. nov. was found with S. shiraishiensis in the Shiraishi-jima Island and S. takeshimensis in Take-shima Island. Remarks: The new species has been identified as S. biwae together with S. nakanoi sp. nov. and assigned as an intraspecific variation of S. niponica. The new species can be discriminated from S. nakanoi sp. nov. and other semisulcospirids by the large, blackish, triangular adult shell with well-granulated ribs and strongly undulating outer lip of the aperture and globose embryonic shells with several brown bands (supplementary fig. S1).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 30-32, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
Semisulcospira nakanoi Sawada 2023, sp. nov.
No full textSemisulcospira nakanoi Sawada sp. nov. [New Japanese name: Chikubu-kawanina] (table 2, supplementary table S2; figs 10, 12M, N) urn:lsid:zoobank.org:act: 9CB53BD3-F776- 4ACB-9C9D-DE0755AADA16 Melania niponica – Annandale, 1916: 45, pl. 3, fig. 3B (part). Melania biwae – Annandale, 1916: 45, pl. 3, fig. 4. Semisulcospira niponica – Kuroda, 1929: 186, 189, pl. 5, fig. 31 (part); Hirase & Taki, 1951: pl. 82, fig. 15; Kuroda, 1962: 86 (part; TAU); Kuroda & Habe, 1965: 57 (part); Habe & Kosuge, 1967: 28, pl. 11, fig. 21 (part); Watanabe, 1984: fig. 3b, f; Watanabe, 1989: 11–13, 47, figs 10, 27, 28 (part). Semisulcospira niponica var. biwae – Fukuoka, 1933: 114, 117, fig. 6. Semisulcospira (Biwamelania) niponica – Nishino, 1991: 9–10, unnumbered figures (part); Kihira et al., 2009: 24–25 (part). Semisulcospira nipponica biwae – Higo & Goto, 1993: 97; Goto & Poppe, 1996: 204. Semisulcospira (Biwamelania) niponica (biwae type) – Watanabe & Nishino, 1995: 17–18, fig. 5b (part). Biwamelania niponica – Nishino & Tanida, 2018: 56, 251 (part). Material examined: Holotype: KUZ Z4122, adult female with embryonic shells treated with sodium hypochlorite, collected from depth of 3.0 m of Lake Biwa at Chikubu-shima, Nagahama City, Shiga Prefecture, Japan, on 9 September 2020 by first author. Paratypes: KUZ Z4123–Z4126, 3 adult females, 1 adult male, collected with holotype. Additional materials: KUZ Z4127, 11 females, KUZ Z4128, 2 males, collected with type specimens; KUZ Z4129, 16 females, KUZ Z4130, 5 males, collected from Onoe Port on 25 July 2021. Etymology: The specific name is dedicated to Dr Takafumi Nakano, who greatly supported the first author’s study of Japanese Semisulcospira. Diagnosis: Viviparous semisulcospirid. Adult shell medium sized (SH 30.6 ± 2.7, 23.1 ± 3.0 mm; BWL 18.9 ± 1.3, 14.8 ± 1.7 mm), nearly triangular (SA 21.5 ± 2.6, 21.4 ± 3.5 degrees); color in black background; outer lip of aperture moderately swell (ASL 0.20 ± 0.05, 0.24 ± 0.06 mm); 2.5 ± 0.5, 2.3 ± 0.6 BCN; longitudinal ribs relatively few, prominently nodulated on penultimate whorl (RN 11.3 ± 1.3, 9.4 ± 1.2); 3.7 ± 0.6, 3.4 ± 0.5 SCN; 1.6 ± 0.1, 1.6 ± 0.1 ASR; 2.9 ± 0.2, 3.2 ± 0.6 WER. Embryonic shell small, with distinct nodes on surface; color in black background or beige background with 3 brown or black bands. Description of holotype: Adult shell (fig. 10A–C): AH 11.5 mm, AL 12.5 mm, ASR 1.48, AW 8.5 mm, BCN 2, BWL 19.7 mm, FWL 4.4 mm; NL 0.18 mm; PWL 7.3 mm, RN 9, SA 23.1 degrees, SCN 4, SH 34.1 mm, SW 15.7 mm, TWL 5.9 mm, WER 2.61; WN 4.75; shell nearly thick triangular; suture hardly undulating; whorl sides slightly convex; outer lip of aperture moderately swell; longitudinal ribs slightly curved, oblique, prominently nodulated in upper to body whorl; apex of shell eroded; shell colored black background without color band. Operculum (fig. 10D): 8.9 mm in long diameter; nearly egg-shaped subcircular, paucispiral, comprising around 3 whorls. Nucleus subcentral. Embryonic shells (fig. 10E–G): EN 62, RNE 12, SHE 2.3 mm, SWE 2.2 mm, WNE 2.5; shell globose; suture prominently undulating; remarkable nodes on central part of whorls and weak keels on lower part of whorls; shell colored beige background with 3 brown or black bands on upper and/or lower part of each whorl and/or on basal part of shell. Radula: Taenioglossa consisting of rachidian in single, lateral teeth, interior and exterior marginal teeth in double row. Rachidian roughly triangular with large central denticle and 3 minor pointed triangular cusps on each side. Lateral teeth with large central denticle, 3–4 inner and outer pointed cusps. Central denticle tip of rachidian and lateral teeth mostly flat; central denticle of rachidian approximately regular triangular, about 2.5 times longer than other triangular cusps; central denticle of lateral teeth irregular triangular, about 1.5 times longer than other triangular cusps. Interior and exterior marginal teeth spoon-shaped with 5–6 rounded denticles. Reproductive organ: 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. Variation: Adult shells (fig. 10M, P): Measurements and counts shown in table 2 and supplementary table S2. Shell nearly thick to elongated triangular; surface sculptures almost straight to slightly curved, oblique, rarely ribbed on upper whorls; shell colored black to brackish olive background with or without several color bands on upper and lower part of each whorl and basal part of shell; surface of shells covered with thin algae layer before treatment. Operculums (fig. 10I, L, N, Q): 7.1–8.9 mm in long diameter. Embryonic shells (fig. 10J, Q): Measurements and counts shown in table 2 and supplementary table S2. Shell with or without keels on lower part of whorls; shell colored blackish brown background or beige background with 3 brown or black bands on upper and/or lower part of each whorl and/or on basal part of shell. Radulae (fig. 12M, N): Rachidian with 2–4 minor pointed triangular cusps on each side; lateral teeth with 2–4 inner and outer pointed cusps; central denticle of rachidian about 1.5 to 4 times longer than other triangular cusps; central denticle of lateral teeth about 1.5 to 4.0 times longer than other triangular cusps; 4–6 rounded denticles in interior and exterior marginal teeth. Reproductive organs: 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: The new species has been found only in Chikubu-shima Island and the coastal Onoe Port in Lake Biwa (fig. 1). Semisulcospira nakanoi sp. nov. inhabits the wharf and rocky bottom of Chikubu-shima Island and concrete blocks around Onoe Port. This species was found with S. morii and S. habei at Chikubu-shima Island. Remarks: The new species has been identified as S. biwae together with S. salebrosa sp. nov. and has been treated as a junior synonym of S. niponica since Kuroda (1929). Semisulcospira nakanoi sp. nov. resembles S. salebrosa sp. nov. with well-developed nodes on the shell surface. However, the former species is distinguishable from the latter by the smaller adult and embryonic shell size and less undulating outer lip of the aperture. The new species can be discriminated from other congeners by its large, blackish, triangular adult shell, prominent granulated ribs, the moderately undulating outer lip of the aperture, and globose embryonic shells with several brown bands (supplementary fig. S1).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 28-30, DOI: 10.1163/18759866-BJA10035, http://zenodo.org/record/834961
Semisulcospira watanabei Sawada 2023, sp. nov.
No full text<i>Semisulcospira watanabei</i> Sawada sp. nov. <p>[New Japanese name: Tokitama-kawanina] (table 2, supplementary table S2; figs 9, 12K, L) urn:lsid:zoobank.org:act: CA379B5F-390A-4369-A921-A65B6CCE33A2</p> <p> <i>Melania niponica</i> – Martens, 1877: 116 (TAU).</p> <p> <i>Melania</i> (<i>Melanoides</i>) <i>niponica</i> – Nevill, 1884: 264 (TAU).</p> <p> <i>Semisulcospira niponica</i> – Kuroda, 1962: 86 (part; TAU).</p> <p> <i>Semisulcospira</i> (<i>Biwamelania</i>) <i>niponica</i> – Nishino, 1991: 9–10, unnumbered figures (part); Kihira et al., 2009: 24–25 (part).</p> <p> <i>Semisulcospira</i> (<i>Biwamelania</i>) <i>niponica</i> (ribbed type) – Watanabe & Nishino, 1995: 17–18, pl. 3, figs n–p (part).</p> <p> <i>Biwamelania niponica</i> – Nishino & Tanida, 2018: 56, 251 (part).</p> <p> <i>Material examined</i>: Holotype: KUZ Z4109, adult female with embryonic shells treated with sodium hypochlorite, collected from depth of 0.3 m of Lake Biwa at Kitakomatsu Port, Otsu City, Shiga Prefecture, Japan, on 28 November 2021 by first author. Paratypes: KUZ Downloaded from Brill.com 08/29/2023 02:12:56AM via free access</p> <p>Z4110–Z4114, 4 adult females, 1 adult male, collected with holotype.</p> <p> <i>Additional materials</i>: KUZ Z4115, 4 females, KUZ Z4116, 2 males, collected with type specimens; KUZ Z4117, 1 juvenile, collected from Oura on 28 November 2021; KUZ Z4118, 12 females, KUZ Z4119, 2 males, collected from Nihonmatsu on 24 January 2021; KUZ Z4120, 15 females, KUZ Z4121, 10 males, collected from Horikiri Port on 28 November 2021.</p> <p> <i>Etymology</i>: The specific name is dedicated to Dr Naoshi Watanabe, who significantly contributed to the systematics of <i>Semisulcospira</i> in Lake Biwa.</p> <p> <i>Diagnosis</i>: Viviparous semisulcospirid. Adult shell small (SH 26.8 ± 3.0, 25.0 ± 2.2 mm, BWL 15.9 ± 1.3, 14.8 ± 1.3 mm), nearly triangular to elongated (SA 21.1 ± 2.7, 20.5 ± 2.5 degrees); color in black or brown background; outer lip of aperture hardly swell (ASL 0.06 ± 0.05, 0.07 ± 0.04 mm); 2.8 ± 0.8, 2.9 ± 0.9 BCN; sculptures prominent, relatively few, ribbed on penultimate whorl (RN 11.1 ± 1.8, 10.1 ± 1.3); 4.6 ± 0.6, 4.4 ± 0.5 SCN; 1.7 ± 0.1, 1.8 ± 0.1 ASR; 2.8 ± 0.2, 3.0 ± 0.2 WER. Embryonic shell small, with distinct nodes on surface; color in black background or beige background with 1–3 brown or black bands.</p> <p> <i>Description of holotype</i>: Adult shell (fig. 9A–C): AH 9.1 mm, AL 9.4 mm, ASR 1.57, AW 6.0 mm, BCN 2, BWL 16.1 mm, FWL 3.4 mm; NL 0 mm; PWL 6.3 mm, RN 11, SA 23.4 degrees, SH 25.0 mm, SW 11.0 mm, TWL 4.5 mm, WER 2.67; WN 3.50; shell nearly thick triangular; suture hardly undulating; whorl sides slightly convex; swell of outer lip of aperture absent; sculpture prominent, almost straight, vertical to oblique, fully ribbed in shell apex to body whorl, faded in body whorl near aperture, spiral striae absent; apex of shell eroded; shell colored black background without color band.</p> <p>Operculum (fig 9D): 6.5 mm in long diameter; nearly egg-shaped subcircular, paucispiral, comprising around 3 whorls; nucleus subcentral.</p> <p>Embryonic shells (fig 9E–G): EN 81, RNE 11, SHE 2.3 mm, SWE 1.8 mm, WNE 3; shell globose; suture moderately depressed by discrepancy in adjacent whorls; nodes remarkable, on central part of whorls, keels weak, on lower part of whorls; shell colored blackish beige background with 3 brown or black bands on upper and/or lower part of each whorl and/or on basal part of shell.</p> <p>Radula: 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 3.5 times longer than other triangular cusps; central denticle of lateral irregular triangular, teeth about 2.5 times longer than other triangular cusps. Interior and exterior marginal teeth spoon-shaped with 4–5 rounded denticles.</p> <p>Reproductive organ: 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.</p> <p> <i>Variation</i>: Adult shells (fig. 9M, O, R): Measurements and counts shown in table 2 and supplementary table S2. Shell nearly slightly elongated triangular; suture hardly to slightly undulating; whorl sides hardly to slightly convex; outer lip of aperture hardly to slightly swell; longitudinal ribs distinct, slightly curved, vertical to oblique, on upper to body whorl; spiral cords indistinct, sometimes absent; shell colored black to brackish brown or beige in background, rarely indistinct brown band on lower part of each whorl and/ or basal part of shell; surface of shells covered with thin algae layer before treatment.</p> <p>Operculums (fig. 9I, L, N, P, S): 5.5–8.2 mm in long diameter.</p> <p>Embryonic shells (fig. 9J, Q, T): Measurements and counts shown in table 2 and supplementary table S2. Shell colored blackish brown background or beige background with 1–3 brown or black bands on upper and/or lower part of each whorl and/or on basal part of shell.</p> <p>Radulae (fig. 12K, L): Lateral teeth with 2–4 inner and outer pointed cusps; central denticle of rachidian about 3.5 to 5.5 times longer than other triangular cusps; central denticle of lateral teeth about 2.5 to 3.0 times longer than other triangular cusps; 4–6 rounded denticles in interior and exterior marginal teeth.</p> <p>Reproductive organs: 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.</p> <p> <i>Distribution and ecology</i>: The known distribution of the new species is discrete and limited to four sites in the coast of Lake Biwa (fig. 1). However, the species may be widespread on the Northern shore of the lake because the ribbed type of <i>S. niponica</i>, whose sculpture type is consistent with S. <i>watanabei</i> sp. nov. has been recorded there (Watanabe & Nishino, 1995, fig. 5b, <i>S</i>. (<i>B.</i>) <i>niponica</i> ribbed). <i>Semisulcospira watanabei</i> inhabits shallow rocky areas and concrete blocks around harbours. The new species was found with <i>S. niponica</i> at Kitakomatsu Port and with <i>S. fuscata</i> at Oura and Nihonmatsu. <i>Semisulcospira watanabei</i> sp. nov. was collected with other Lake Biwa species: <i>S. habei</i> at Oura, Nihonmatsu, and Horikiri Port; <i>S. decipiens</i> at Oura and Nihonmatsu.</p> <p> <i>Remarks</i>: The new species was first described as an intraspecific variation of <i>S. niponica</i> by Watanabe and Nishino (1995). <i>Semisulcospira watanabei</i> sp. nov. can be discriminated from <i>S. niponica</i> in the smaller size of the adult and embryonic shell and fewer prominent longitudinal ribs on the shell surface. Traits of a blackish, elongated triangular adult shell, prominent longitudinal ribs, and globose embryonic shells with several brown bands distinguish <i>S. watanabei</i> sp. nov. from other <i>Semisulcospira</i> species (supplementary fig. S1).</p>Published as part of <i>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)</i> on pages 26-28, DOI: 10.1163/18759866-BJA10035, <a href="http://zenodo.org/record/8349612">http://zenodo.org/record/8349612</a>
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