Cerithidea obtusa ( Lamarck, 1822 )

Reid, David G., 2014, The genus Cerithidea Swainson, 1840 (Gastropoda: Potamididae) in the Indo-West Pacific region, Zootaxa 3775 (1), pp. 1-65 : 27-31

Cerithidea obtusa ( Lamarck, 1822)

( Figures 2 B, 8, 9)

Cerithium obtusum Lamarck, 1822: 71 (“les mers de Timor”, probably in error, see Range below;

lectotype MHNG INVE 51623 (formerly 1097/25), here designated, 43.8 mm, Fig. 8 A;

in part, includes C. anticipata ). Kiener, 1841 –1842: 95–96, pl. 29, fig. 1 (in part, includes C. anticipata ). Hombron & Jacquinot, 1848: pl. 23, fig. 3 (living animal). Souleyet, 1852: 600, Atlas pl. 39, figs 1, 2 (living animal). Rousseau, 1854: 96. Sowerby, 1855: 885, p. 186, fig. 271. Hanley, 1856: 215, suppl. pl. 4, fig. 8.

Strombus obtusus — Wood, 1828: 13, pl. 4, fig. 8. Hanley, 1856: 215, suppl. pl. 4, fig. 8.

Cerithidea obtusa — H. Adams & A. Adams, 1854: 292–293, pl. 31, fig. 2b. Adams, 1855: 83. Sowerby, 1866: sp. 4, pl. 1, fig. 4a, b. Morlet, 1889: 144. Van Benthem Jutting, 1956: 433 –435, fig. 106. Habe & Kosuge, 1966: 25, pl. 7, fig. 23. Subba Rao & Mookherjee, 1975: 170. Subba Rao, Dey & Barua, 1983: 51, pl. 2, fig. 2. Houbrick, 1986: 284, figs 7, 8, figs 10 and 14 (radula). Subba Rao, Dey & Barua, 1992: 177, pl. 5, figs 3, 6. Poutiers, 1998: 450, fig. Dharma, 2005: 92, pl. 21, fig. 8. Thach, 2005: 49, pl. 10, fig. 4. Dey, 2006: 35 –36, figs 38–40. Ahmed & Mahmoud, 2007: 9, 95, figs pp. 9, 95 (in part, includes C. weyersi ). Reid et al., 2008: 680 –699, figs 1, 2 (phylogeny), 2H. Hamli et al., 2013: 412 –418, fig. 2a. Reid et al., 2013: figs 1 (shell, phylogeny), 2 (map).

Potamides (Cerithidea) obtusus —von Martens, 1880: 282. von Martens, 1887: 168. Tryon, 1887: 161, pl. 33, figs 59–60 (as obtusa ; in part, includes C. quoyii , C. anticipata ). von Martens, 1897a: 186 –187; pl. 9, fig. 22; pl. 10, fig. 5 (head). von Martens, 1897b: 266. Fischer & Dautzenberg, 1904: 416. Oostingh, 1923: 76 –77, fig. 12. Dautzenberg, 1929: 489.

Cerithium (Cerithidea) obtusum — Kobelt, 1890a: 42 –43, pl. 9, figs 3–5 ( Cecalupo 2005: pl. 31, fig. 10).

Potamides obtusum — Prashad, 1921: 495.

Cerithidea (Cerithidea) obtusa — Brandt, 1974: 192 –193, pl. 14, fig. 52. Houbrick, 1984: 15, 16, fig. 5C. Subba Rao, Surya Rao & Maitra, 1991: 44. Subba Rao, Dey & Barua, 1995: 45, 58. Glaubrecht, 1997: 299, pl. 12, fig. 6. Subba Rao, 2003: 136, pl. 22, figs 5, 6. Cecalupo, 2005: 316, pl. 31, fig. 10. Cecalupo, 2006: 116, 223, pl. 57, fig. 12a–c. Ramakrishna et al., 2007: 47.

Cerithium decollatum —Sowerby, 1834: pl. 214, fig. 2 (not Linnaeus, 1767). Reeve, 1842: 178, pl. 227, fig. 2 (not Linnaeus, 1767).

Melania lineolata Gray in Griffith & Pidgeon, 1833: pl. 14, fig. 4

(no locality; holotype NHMUK 20130227,

seen; not Wood, 1828).

Cerithidea lineolata — Swainson, 1840: 342.

Cerithium truncatum ‘Lam.’ Griffith & Pidgeon, 1834: 596, 598 (refers to pl. 14, fig. 4; as Cerethium p. 598;

no locality; holotype NHMUK 20130227, seen ;

not Gray in Griffith & Pidgeon, 1833: pl. 13, fig. 1).

Cerithidea ornata — Li, 2008: 82, fig. (not Sowerby, 1855).

Taxonomic history. This species has been recognized under its original specific name by almost all authors, although there was some early misidentification as C. decollata (e.g. Sowerby 1834; Reeve 1842). The original concept of the species was broader than today; Lamarck’s (1822) description of his Cerithium obtusum included a ‘var. b’, which referred to C. anticipata . This was followed by Kiener (1841 –1842) and Tryon (1887) also had a broad concept of the species. As recorded by Lamarck’s daughter Rosalie (in an annotated copy of his Histoire Naturelle de Animaux sans Vertèbres), his collection contained a single specimen of the typical form of Cerithium obtusum and two of var. b (the latter, registered as MHNG INVE 51622, formerly MHNG 1097/24, are C. anticipata and have no type status; ICZN 1999: Art. 72.4.1). There are, however, currently two specimens in the lot of the typical form, one an adult (H = 43.8 mm; Fig. 8 A) and the other a juvenile (H = 37.8 mm) (Y. Finet, pers. comm.). Lamarck (1822) gave “19 lignes” (= 42.7 mm) for the typical form, so the larger shell corresponds most closely with his description. It may be the holotype but, to avoid any potential for future ambiguity, it is here designated lectotype.

This is the type species of the genus Cerithidea , but the designation refers to its synonym, Melania lineolata , and the case is a complicated one. The molluscan taxa introduced in volume 12 of Griffith’s edition of Cuvier’s Animal Kingdom have been discussed in detail by Petit & Coan (2008), including their authorship and dates of publication. Briefly, some of the molluscan plates (including plates 13 and 14) were newly drawn for the molluscan volume ( Griffith & Pidgeon 1833 –1834), from specimens in NHMUK provided by Gray. While Gray may also have supplied the names used in the legends (i.e. text appearing on the plates themselves), the index (an alphabetical list of species figured in the plates) was prepared by someone else and contains “many errors and misattributions of species” ( Petit & Coan 2008: 222). In their commentary on the availability of names, Petit & Coan (2008) adhered strictly to the published evidence. Thus in the legend of plate 14 the shell illustrated in figure 4 (here shown to be C. obtusa , see below) is labelled Melania lineolata , which they interpreted as an available but invalid name (a junior homonym of Melania lineolata Wood, 1828 ) attributed to Gray and published in 1833. Previous authors, including Swainson (1840), Bequaert (1942a, b) and Houbrick (1984), have also reached the same conclusion. Since Wood’s species was illustrated and correctly labelled on the preceding plate 13, and because the genera Melania and Cerithium (in a broad sense, to include Cerithiidae and Potamididae ) were clearly diagnosed in the main text and would not have been confounded by the experienced Gray, it seems more likely that the legend of plate 14, figure 4, was simply an error. This error was corrected in the index of the volume, published the following year (Griffith & Pidgeon 1834). On page 596 the caption to plate 14, figure 4, is given as “ Cerithium truncatum, Lam. ” and this is repeated on page 598 (without the attribution); Bequaert (1942b) and Petit & Coan (2008) have interpreted this action as a replacement name for the preoccupied Melania lineolata . Again, without evidence of intent by the original authors, this seems questionable, because the name was attributed to Lamarck (who introduced no such name); more plausibly, this was another error, for Lamarck’s Cerithium obtusum , a name of similar descriptive meaning. To compound the confusion, the name Cerithium truncatum had been used for plate 13, figure 1, and was subsequently renamed “ Cerithium laeve, Gray ” in the index (this is the species now known as Campanile symbolicum Iredale, 1917 ). Both Iredale (1917: 326) and Houbrick (1981: 283) described the use of Cerithium truncatum in this latter context as “a careless slip” and did not accept it as an available name. However, Petit & Coan (2008) did accept it as available and therefore a senior homonym of the replacement name for the shell of plate 14, figure 4. Regardless of this speculation about the original intent of Gray and likelihood of errors in the publication of Griffith & Pidgeon, it is recommended that the strict interpretation of Petit & Coan (2008) should be followed (see Synonymy above). This has no effect on the valid name of the present species, since both the synonyms are junior primary homonyms. It does, however, have an implication for the concept of the genus Cerithidea because, in introducing the genus, Swainson (1840) gave “ C. lineolata . Griff. Cuv. 14. f. 4” (i.e. Melania lineolata Gray in Griffith & Pidgeon, 1833) as one of only two originally included species (the other being a fossil), which was subsequently designated type species by Makiyama (1936). For stability, it is therefore important to accept this name as available. If considered unavailable from Griffith & Pidgeon (1833), the name could still be accepted as available as Cerithidea lineolata Swainson, 1840 , because Swainson’s reference to the published figure is a valid indication of the name (ICZN 1999: Art. 12.2.7).

The original figure of Melania lineolata Gray in Griffith & Pidgeon, 1833 shows a rather elongate spire and the apertural lip is neither extremely flared nor strongly thickened. For these reasons Reid (quoted in Petit & Coan 2008) suggested it might represent C. reidi , rather than C. obtusa as previously interpreted (e.g. Houbrick 1984). The original shell has since been discovered (NHMUK 20130227), proving that the figure was poorly drawn from an oblique angle and that it is indeed a specimen of C. obtusa .

Diagnosis. Shell: large, solid, broad, periphery rounded; aperture strongly thickened and flared; 14–37 rounded axial ribs on penultimate whorl; ventrolateral varix a moderate rib at 200–270°; 5 spiral cords on spire, 5– 9 above periphery on last whorl; often a broad brown band from periphery to shoulder. E India, SE Asia to Borneo and Java. COI GenBank HE680209 –680219, AM932765 .

Material examined. 106 lots.

Shell ( Fig. 8 ): H = 31.3–57.2 mm. Shape relatively broad, elongated conical (H/B = 1.78–1.91, SH = 2.20– 2.59); decollate, 5–7 whorls remaining; spire whorls rounded, suture distinct; spire profile straight to slightly convex; periphery rounded, not marked by cord or keel; solid. Adult lip strongly thickened and flared; apertural margin planar in side view; strong anterior projection adjacent to canal. Sculpture on spire of slightly opisthocline curved (opisthocyrt) axial ribs, occasionally bifurcating posteriorly (adapically), usually weaker and more distant on final 0.3 whorl; ribs prominent, rounded, interspaces 1–2 times width of ribs, 14–37 ribs on penultimate whorl; occasionally 1–2 varices on spire; spire whorls with 5 spiral cords, intersecting with axial ribs to give reticulate sculpture, increasing by interpolation of narrower cords to 6–9 spiral cords above periphery on final whorl; base with 10–13 cords, only slightly narrower than those above periphery and not separated from them. Ventrolateral varix a slightly to moderately thickened rib at 200–270°. Surface with fine spiral microstriae on periostracum. Colour: fawn, usually a broad dark brown band from shoulder to periphery and another on base; aperture white, pale brownish within.

Animal ( Fig. 2 B): Head and base of tentacles grey with pale yellow spots; snout dark grey with 3 transverse bands of orange red, the 2 posterior bands wavy or interrupted and with a broad black band between; eyes with black surround and red ring; tentacles pinkish grey, darker at base; sides of foot dark grey with red spots and red margin; mantle cream (red colour fading to dark pink in ethanol-preserved specimens.)

Range ( Fig. 9 ): Bay of Bengal, Malay Peninsula, S Vietnam, Sumatra, Java, Borneo. Records: India: Pichavaram, Tamilnadu ( Sreenivasan & Natarajan 1986; Subba Rao 2003); Godavari Estuary, Andhra Pradesh ( Subba Rao, 2003); Port Canning, West Bengal ( NHMUK 1893.12.2.119) . Bangladesh: R. Ganges ( ZMB). Burma: Moulmein, Salween R. ( NHMUK 1954.6.2.2). Thailand: Ko Nok, Satun Prov. ( NHMUK; MNHN; RMNH; AM C.079263; USNM 777316); Kanchanadit, Surat Thani Prov. ( NHMUK 20100436; USNM 828815); Ban Tamrua, Chonburi Prov. ( USNM 776723). Malaysia: Klang, Selangor ( NHMUK; USNM 661023; ANSP 267498); Kuantan, Pahang (AM C.124490); Simunjan, Sarawak ( ZMB 112.764). Singapore: Pulau Ubin ( NHMUK 20130239). Cambodia: Kampot ( Morlet 1889). Vietnam: Vung Tau ( ANSP 330753); Long Hai ( NHMUK); Khanh Hoa ( Thach 2005). Indonesia: Pulau Weh, Sumatra ( RMNH); Pulau Bangka (AM C.009036); Tanjung Priok, Java ( RMNH); Pasuruan, Java ( RMNH); Banjarmasin, Kalimantan ( RMNH); 14 km N Mahakan R., Kalimantan (AM C.410364).

Lamarck (1822) gave the type locality as “Mers de Timor” but, at this early date, this might refer to a wider region than the island of Timor. There are in addition four museum records from Timor (RMNH; ANSP 18055; ZMB), but all are old and are considered unreliable; the locality may have been copied from Lamarck, or ships returning to Europe from Timor may also have acquired specimens from Java or elsewhere. Three species of Potamididae were listed from the mangroves of Timor by Studer (1889), but C. obtusa was not among them.

The Australian C. reidi and C. anticipata have sometimes been misidentified as C. obtusa (see their respective Synonymies). Houbrick (1986: 284), while distinguishing all three, also noted that C. obtusa “does not appear to be common in Australia, although there are some reliable records from Queensland”. In fact there is no evidence that C. obtusa occurs in Australia. Among other authors, von Martens (1897a, b) included Australia and Madagascar in the recorded distribution; Brandt (1974) included Madagascar, Philippines and Australia; and Poutiers (1998) also mentioned Madagascar. Its incorrect occurrence in Madagascar can be traced to the record by Kiener (1841 –1842), who was later quoted by von Martens (1880) and Dautzenberg (1923, 1929). The distribution in India has been said to include the Andaman and Nicobar islands ( Subba Rao 2003; Subba Rao et al. 1992), but this is unsubstantiated; occurrence of Cerithidea there could refer to C. andamanensis . Records of shells outside its natural range could possibly be a consequence of its widespread use as food in Southeast Asia.

Habitat and ecology. In Rhizophora and Bruguiera forest, Avicennia parkland and landward fringes of mangrove forests, on firm mud and on trunks and stilt roots up to 1–1.5 m above the ground; in fully marine and estuarine areas. It has been recorded from the Rajang River at Sibu, Sarawak ( Hamli et al. 2013), 60 km from the open sea. Several authors have observed that C. obtusa rests on branches, roots and trunks of trees, and descends to feed on firm mud below as the tide recedes, before climbing again during the ebb tide ( Sreenivasan & Natarajan 1986; Ahmed & Mahmud 2007); according to Berry (1972) descent to the forest floor occurs during neap tides in Malaysia. In Malaysia and Thailand the animals are often found close to the ground on the bases of trees and on firm mud among tree roots (pers. obs.), but presumably climb higher to avoid submersion during spring tides. In Bangladesh the snails are said to be often found partly buried in the mud with the top of the spire projecting ( Ahmed & Mahmud 2007). Densities of 2–10 /m2 have been recorded in Sundarbans ( Subba Rao et al. 1983, 1995; Dey 2006). It was rare in a mangrove forest at Phuket, Thailand, perhaps as a result of collection for food by local people ( Frith, Tantanasiriwong & Bhatia 1976). According to the growth rate estimated by Sreenivasan & Natarajan (1986) in India, 13 mm is achieved at the end of the first year and maximum size of 26 mm after 4 years. Houlihan (1979) measured an air/water respiration rate ratio of 5.5 at 28°C and reported 50% death after submersion for 48 h, also at 28°C.

Remarks. The sculpture of the shell is quite variable (as observed by Sowerby 1866: fig. 4a, b), specimens from India and Bangladesh ( Fig. 8 G, H) usually having finer sculpture than the typical form from the western Pacific ( Fig. 8 I), but both can be found, together with intermediates, on the west coast of the Malay Peninsula (Fig. B–F, J–M). A phylogeographic break between Indian and Pacific oceans is common in shallow-water marine organisms (e.g. Reid et al. 2006; Carpenter et al. 2011) and in some cases sister species occur in each ocean ( Gaither & Rocha 2013), but the existence of intermediates suggests conspecificity in the case of C. obtusa . In addition, the distinctive coloration of the body is the same in both forms; Subba Rao (2003: 136) reported “alternating broad black and red bands” on the head in India. Samples often show size dimorphism of small and large shells (e.g. Fig. 8 G, H), which presumably represent male and female individuals.

The species is commonly used for food in Southeast Asia and Indonesia ( Brandt 1974; Poutiers 1998; Hamli et al. 2013).

Cerithidea obtusa is a member of a large clade of Cerithidea species (excluding the C. balteata group and C. weyersi ), but within this its relationships are not clearly resolved in molecular phylogenies ( Reid et al. 2013; Fig. 1 ). The shell is similar to that of C. anticipata , but is larger, broader and more robust. It is also close to C. reidi , which is of similarly large size, but paler in colour. Cerithidea obtusa differs from both these congeners ( Fig. 10 ) in its more thickened and flared aperture.

Figures

FIGURE 1. Molecular phylogeny of Cerithidea species produced by Bayesian analysis of partial COI sequences, using Cerithideopsilla species as outgroup (after Reid et al. 2013). Localities details given by Reid et al. (2013). Support values are posterior probabilities; only values ≥ 0.95 (i. e. with strong support) are shown.

FIGURE 2. Living animals of Cerithidea species (not to scale). A. C. charbonnieri, Tapi R. estuary, Surat Thani, Thailand. B. C. obtusa, W Johore, Malaysia. C. C. anticipata, Brunswick R., NSW, Australia. D. C. quoyii, Singapore. E. C. moerchii, Kumamoto City, Kumamoto Pref., Kyushu, Japan. F. C. tonkiniana, Kumamoto City, Kumamoto Pref., Kyushu, Japan. G. C. reidi, Port Smith, Western Australia. H. C. weyersi, Tha Pom, Krabi, Thailand. Photography credits: C, D. Riek; D, S. K. Tan; E, F, H. Fukuda (from Fukuda, 2000). H, B. Craig.

FIGURE 8. Cerithidea obtusa. A, Cerithium obtusum Lamarck, 1822, lectotype, Timor (probably in error) (MHNG INVE 51623). B – E, Melaka, Malaysia (NHMUK 20130237; views of same specimen). F, Phuket I., Thailand (NHMUK 20100441). G, H, Port Canning, West Bengal, India (NHMUK 20130240). I, Jelutong, Pulau Ubin, Singapore (NHMUK 20130239). J – M, Melaka, Malaysia (NHMUK 20130238; views of same specimen). Photography credit: A, MHNG.

FIGURE 9. Distribution of Cerithidea obtusa (circles) and C. decollata (triangles). Solid symbols, specimens examined; open symbols, literature records: A, Sreenivasan & Natarajan (1986); B, Thach (2005); C, Morlet (1889); D, Ramakrishna et al., (2007); E, Subba Rao et al. (1991); F, Macnae (1963); G, Fischer-Piette & Vukadinovic (1973).

FIGURE 10. A – P, Cerithidea anticipata. Q – V, C. reidi. A, Cerithium kieneri Hombron & Jacquinot, 1848, holotype, Raffles Bay, Coburg Peninsula, Northern Territory, Australia (MNHN 25692). B, C, Buffalo Creek, Northern Territory, Australia (NHMUK 20130241). D, Casuarina Beach, Northern Territory, Australia (NHMUK 20130242). E – G, Kokenau, Mimika R., East Papua, Indonesia (AM C. 458258). H, I, Rowes Bay, Townsville, Queensland, Australia (NHMUK 20130243). J, Moa I., Torres Strait, Queensland, Australia (NHMUK 20130244). K – M, Moreton Bay, Queensland, Australia (NHMUK 20130245; views of same specimen). N – P, Merauke, East Papua, Indonesia (AM C. 121289; N, O views of same specimen). Q – V, Willies Creek, N of Broome, Western Australia (NHMUK 20130246; same lot as type series; T – V views of same specimen). Photography credit: A, MNHN.