Cerithideopsis largillierti (Philippi, 1848) (Figures 2A–E, 3A, 4) Cerithium (Potamides) largillierti Philippi, 1848: 20 (China; neotype here designated NHMUK 20130431/1, Shanghai, China, Fig. 2B). Philippi, 1849: 15, Cerithium pl. 1, fig. 7 (cited as fig. 6 in error, p. 15; Fig. 2A herein). Cerithidea (Pirenella) largillierti —H. Adams & A. Adams, 1854: 293. A. Adams, 1855: 84. Cerithium (Cerithidea) largillierti —Kobelt, 1890: 65, pl. 13, figs 2, 3 (Cecalupo, 2005: pl. 32, fig. 25). Cerithidea largillierti — Dautzenberg & Fischer, 1905: 135. Hirase, 1934: 53, pl. 84, fig. 9. Kuroda & Habe, 1952: 44. Habe & Kosuge, 1967: 34, pl. 13, fig. 12. Habe, 1968: 38, pl. 11, fig. 25. Higo, 1973: 79. Fan, 1989: 38–39, pl. 5, fig. 26. Choe, 1992: 310, pl. 65, fig. 102. Higo & Goto, 1993: 105. Higo, Callomon & Goto, 1999: 87. Fukuda, 2000: 109, 135, figs 5.4c, 5.5c (headfoot). Ma, 2004: 38, pl. 016E. Min et al., 2004: 129, figs 219-1, 219-2. Kojima et al., 2006: 525–535, fig. 2e–g. Li & Huang, 2012: 152, fig. Cerithidea (Cerithidea) largillierti — Oyama, 1959: Cerithidea plate, figs 6, 13 (as C. largillerti). Fukuda, 1996: 21, pl. 3, fig. 5. Hasegawa, 2000: 133, pl. 66, fig. 3 (in part, includes C. malayensis, C. australiensis). Hong, Choi & Tsutsumi, 2010: 260, fig. 4a. Fukuda & Kimura, 2012: 28, text fig. a (living animal), b, c (shells). Cerithidea? largillierti — Houbrick, 1984: 16 (in part, includes C. australiensis). Cecalupo, 2005: 318, pl. 32, fig. 25. Cecalupo, 2006: 87, 211. Cerithideopsis largillierti — Reid et al., 2008: 680–699 (in part, includes C. australiensis). Lozouet & Plaziat, 2008: 112 (in part, includes C. australiensis, C. malayensis). Cerithidea fortunei A. Adams, 1855: 85 (China; lectotype NHMUK 20130431/1, Fig. 2B; 2 paralectotypes NHMUK 20130431/2, Fig. 2C, 20130413/3, Fig. 2D). Sowerby, 1866: sp. 15, pl. 3, fig. 15a, b. Yen, 1942: 207, pl. 15, fig. 77. Potamides (Cerithidea) fortunei — Tryon, 1887: 162, pl. 33, figs 65, 66. Fischer & Dautzenberg, 1904: 416. Iwakawa, 1919: 76. Cerithium montagnei — Sowerby, 1855: 888, pl. 186, fig. 286 (in part, includes C. montagnei, C. pulchra; not d’Orbigny, 1841). Cerithidea montagnei — Sowerby, 1866: sp. 26 (in part, includes C. montagnei; not d’Orbigny, 1841). Cecalupo, 2006: 70, 202 (in part, includes C. montagnei; not d’Orbigny, 1841). Potamides (Cerithidea) montagnei — Tryon, 1887: 161 (in part, includes C. montagnei, C. pulchra; not d’Orbigny, 1841). Cerithidea ornata — Yoo, 1995: 61, pl. 9, figs 7, 8. Min et al., 2004: 129, fig. 218 (both not Cerithium ornatum ‘A. Adams’ G.B. Sowerby II, 1855 = Cerithidea balteata (A. Adams, 1855)). Taxonomic history. The original description by Philippi (1848) was brief and he only figured the species later (Philippi 1849). This may explain why Adams (1855) listed it as a distinct species in his monograph on Cerithidea, while also naming Cerithidea fortunei. The synonymy of these two names was noted by Sowerby (1855), although he erroneously considered both to be synonyms of Cerithium montagnei (= C. montagnei), a species from the Pacific coast of Central America. This error was pointed out by Carpenter (1857: 343), but Cerithium largillierti was still listed under Cerithidea montagnei by Sowerby (1866) and Tryon (1887). Meanwhile, Cerithidea fortunei continued to be widely used as the name of the present species (Sowerby 1866; Tryon 1887; Fischer & Dautzenberg 1904; Iwakawa 1919). The name Cerithidea largillierti was reinstated by Dautzenberg & Fischer (1905) and thereafter this specific name has been almost universally used. There has been occasional misidentification as ‘ Cerithidea ornata ’ (Yoo 1995; Min et al. 2004). No type material of Cerithium largillierti has been traced (not present in MNHN, ZMB or SMF, which all contain some specimens of other species collected by Largilliert and/or described by Philippi). Philippi’s (1849) figure could serve as lectotype, but is not clearly drawn (Fig. 2A) and an actual specimen is desirable. Therefore, a shell from Shanghai is here designated the neotype (NHMUK 20130431/1; Fig. 2B). This shell is also one of the syntypes of C. fortunei A. Adams, 1855. To avoid any possible confusion, and to reinforce the synonymy, this specimen is also designated the lectotype of C. fortunei. Diagnosis. Shell of medium size (to 36 mm), brown with two pale spiral bands above periphery; animal black with yellow tip to snout and tentacle bases; northern Vietnam, China, Korea, southern Japan; COI: AM 932788, AM 932789, HE680618, HE680623. Material examined. 22 lots. Shell (Fig. 2A–E): H = 23.9–35.9 mm. Shape elongated conical (H/B = 2.17–2.42, SH = 2.88–3.31); not routinely decollate, 9–11 whorls remaining in well preserved shells, but apex and protoconch always eroded. Spire whorls rounded, suture distinct; spire profile slightly convex, slightly concave towards apex; periphery rounded; relatively solid. Adult lip only slightly thickened, not flared; sometimes 1–2 previous lips on final whorl; apertural margin sinuous in side view; anterior canal a weak notch. Sculpture on spire of straight axial ribs, usually becoming curved (opisthocyrt) on last 2–3 whorls, ribs rounded, ribs and interspaces of similar width, 20–26 ribs on penultimate whorl, ribs becoming weaker and irregular on final whorl; 3–6 spiral cords on smallest apical whorls if well preserved, macroscopic spiral sculpture usually absent above periphery of larger whorls, sometimes 10–13 weak spiral elements visible between axial ribs on last 2 whorls; base with 8–9 cords, of which two at periphery are strong, with marked groove between, those towards columella becoming smaller. No ventrolateral varix, but 0–2 indistinct or prominently raised and rounded varices may be present at any point on last 2 whorls (Fig. 2D). Surface with spiral microstriae on thick periostracum, short periostracal fringe or bristles remaining on larger striae (i.e. 10–13 striae macroscopically visible above periphery) if well preserved; shiny where periostracum worn away; surface often covered by thick black concretion, presumably of microscopic algae and sediment. Colour: brown, with pale band just above periphery and another at shoulder, often indistinct beneath periostracum; aperture brown with indistinct pale bands. Animal (Fig. 3A): sides of foot black, paler towards margin; head grey, snout black, snout tip and tentacle bases yellow. Yellow coloration not preserved after storage in ethanol, but pattern visible as absence of black pigment (examined in two lots from Japan and Korea). Range: N Vietnam, China, Taiwan, S Korea, S Japan. Records: Vietnam: Quikim, Hai Phong (NHMUK; ZMSP). China: Tsim Bei Tsui, Hong Kong (NHMUK); Shanghai (NHMUK 20130431; ZMB; ANSP 275721); “throughout Chinese coasts” (Ma 2004: 38). Taiwan: Hsinchu (Yan Yu-Xiu; photo seen). S Korea: Daehang-ri, Byeonsan-myeon, Buan-gun, Jeollabuk-do (NHMUK 20070408); Suncheon Bay (Kamimura et al. 2010). Japan: Nagasaki (USNM 343900); Hikawa, Kumamoto Pref. (NHMUK); Onoda City, Yamaguchi Pref. (NHMUK); Tokyo (USNM 343901; Callomon & Goto 1999: quoting Okamoto 1995; Hasegawa 2000). Habitat and ecology. Mud flats at high tidal levels, on bare mud and among Phragmites reeds, often at river mouths; among saltmarsh vegetation (Korea) and at margins of brackish shrimp ponds (northern Vietnam). Remarks. Over much of its range this species overlaps with two other potamidids, Cerithidea sinensis (Philippi) (China and northern Vietnam) and Cerithidea tonkiniana Mabille (Vietnam to southern Japan) (see Reid 2014 for detailed descriptions). The shells of these Cerithidea species are decollate as adults, the aperture is more strongly flared (and planar, not sinuous, in Cerithidea tonkiniana), the whorls less rounded, the axial ribs less numerous (14–19 in Cerithidea sinensis; 11–25 in Cerithidea tonkiniana), the periostracum is thin and the ventrolateral varix often present. The living animals also differ. That of Cerithidea sinensis has a cream head and foot with grey mottling, the tip of the snout is yellow with two transverse black bands just behind, and the tentacle yellow at the base with a black stripe across the eye. That of Cerithidea tonkiniana has a blackish foot, a grey head with cream spots, the anterior half of the snout is blackish with yellow spots arranged in 2–3 transverse bands, and the tentacle is grey with black rings and a black base. For comparison between the three species of Cerithideopsis in the Indo-West Pacific, see Remarks on C. australiensis below and Table 2. There have been two genetic studies of C. largillierti. Kojima et al. (2006) found two shared haplotypes of COI and no significant differences in frequencies between Japan and China. This was interpreted as suggesting recent migration between the two regions, either during the last glacial stage when there was a connection between Kyushu and Korea, or through a possible planktotrophic larva (larval development is unknown in this species). Kamimura et al. (2010) reported that COI haplotypes were of low diversity in Suncheon Bay, South Korea. The species inhabits threatened wetlands in southern Japan, where it has been listed as endangered (Fukuda 1996) or vulnerable (Fukuda & Kimura 2012).

Published as part of Reid, David G. & Claremont, Martine, 2014, The genus Cerithideopsis Thiele, 1929 (Gastropoda: Potamididae) in the Indo-West Pacific region, pp. 61-80 in Zootaxa 3779 (1) on pages 68-70, DOI: 10.11646/zootaxa.3779.1.8, http://zenodo.org/record/4910133