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The study was conducted in July 2018. Sampling of sedut snails (Cerithidea obtusa) which was carried out in the waters of Mendol Island, Kuala Kampar District, Pelalawan Regency was aimed to determine the differences in the content of Pb, Cu and Zn between slugs and sediments and to know the consumption limits and the level of heavy metal pollution in the waters of Mendol Island. The method used in this study is the survey method. Sampling was determined using purposive sampling. The results of this study indicate the value of the metal content of Pb, Cu, and Zn in sedut snail highest at station 2, respectively: 9,2633 µg / g, 72,040 µg / g, 111,748 µg / g. Whereas for Pb, Cu, and Zn metals, the highest sediment was found at station 2, namely: 23.990 µg / g, 4.795 µg / g, 48.587 µg / g The results of linear regression analysis of Pb metal concentrations in snail meat showed negative results, and the concentration of Zn and Cu metals in snail meat showed positive results. namely Pb with a value of 14.1930 kg / week on Zn metal with a value of 111.7483 kg / week, while Cu metal at station 2 with a value of 72.0400 kg / week

International audience; Mangrove sediments can store high amount of pollutants that can be more or less bioavailable depending on environmental conditions. W hen in available forms, the se elements can be subject to an uptake by mangrove biota, and can thus become a problem for human health. The main objective of this study was to assess the distribution of some trace elements (Fe, Mn, Co, Ni, Cr, As, and Cu) in tissues of different plants and snails in a tropical mangrove (Can Gio mangrove Biosphere Reserve) developing downstream a megacity (Ho Chi Minh City, Vietnam). In addition, we we re interested in the relationships between mangrove habitats, sediment quality and bioaccumulation in the different tissues studied. Roots and leaves of main mangrove trees (Avicennia a lba and Rhizophora apiculata) were collected, as well as different snail species: Chicoreus capucinus, Littoraria m el ano st oma , Cerithidea obtusa, Nerita articulata. Trace elements concentrations in the different tissues were determined by ICP-MS after digestion with concentrated HNO3 and H2O2. Concentrations differed between stands and tissues, showing the influence of sediment geochemistry, species specific requirements, and eventually adaptation abilities. Regarding plants tissues, the formation of iron plaque on roots may play a key role in preventing Fe and As translocation to the aerial parts of the mangrove trees. Mn presented higher concentrations in the leaves than in the roots, possibly because of physiological requirements. Non-essential elements (Ni, Cr and Co) showed low bioconcentration factors (BCF) in both roots and leaves, probably resulting from their low bioavailability in sediments. Regarding snails, essential elements (Fe, Mn, and Cu) were the dominant ones in their tissues. Most of snails were "macroconcentrators" for Cu, with BCF values reaching up to 42.8 for Cerithidea obtusa. We suggest that high quantity of As in all snails may result from its high bioavailability and from their ability to metabolize As.

Objective: To study the possible effects of Cerithidea obtusa extract as antidiabetic and to screen the secondary metabolites presence. Methods: Antidiabetic activity of Cerithidea obtusa extract was measured in vitro using α-glucosidase inhibition method. Whereas, secondary metabolites screening was measured qualitatively. Results: The methanol extract had antidiabetic activity (IC50 = 36.40 mg/mL). However, the control drug acarbose had significantly higher antidiabetic activity (IC50 = 0.32 mg/mL). Secondary metabolites screening showed the presence of alkaloids, flavonoids, triterpenoids and saponins. Conclusions: The methanol extract had antidiabetic activity and the presence of alkaloids, flavonoids and triterpenoids might contribute to the activity.

International audience; We sequenced the complete mitogenome of the red chut-chut snail Cerithidea obtusa, from the Cần Giờ mangrove in Vietnam. The mitogenome is 15,708 bp long. It is colinear with the mitogenomes of other members of the superfamily Cerithioidea, and the maximum-likelihood phylogeny obtained with the cox1, cox2 and cox3 genes of several Caenogastropoda associated all Cerithioidea together inside a strongly supported clade.

Snail Cerithidea obtusa has an important role in the mangrove ecosystem as a decomposer and this species generally serve as food in some Southeast Asian countries, especially in Indonesia. The research of the population studies the snail in the mangrove forest of Pangkal Babu was conducted in January to February 2012. In conducting the research, we divided the sites into 3 stations by using the Purposive Random Sampling. The average of density population ranges between 3.87–7.87 ind/m2. The highest of average density population was founded in station 3, which was located in the back of the mangrove forest. It was dominated by plants of Avicennia sp. and Rhizophora sp. The snail has cluster spreading pattern. The shell length was measured between 1.8–4.4 cm, the weight was between 0.38–1.8 grams, and biomass ranges from 0.3–1.8 grams. The Spearman correlation test results indicated there was no correlation between the density of C. obtusa and abiotic parameters.

Red Eye Snail (Cerithidea obtusa) is one species of marine gastropod utilized by coastal communities as a source of animal protein other than fish. Cerithidea obtusa is exploited with varying sizes. This research was conducted at intertidal zone of Pulau Tebing Tinggi beach, Meranti Island regency, Riau from May to June 2017. The objective of the research was to analyse morphometric variation and long-term relationship of Cerithidea obtusa. Samples of Cerithidea obtusa were randomly collected and morphometric parameters measured included shell length, shell width, spire height, shell opening length, shell opening width, and shell depth using digital calipers. The results showed that the long shell of Cerithidea obtusa varied between 21-43 mm, while the width of the shell varied between 13-24 mm. Cerithidea obtusa has a low spire with an oval body shape based on the ratio of shell length to shell width parameters, spire height, shell opening length, shell opening width and shell depth. The relative growth pattern of Cerithidea obtusa is negative allometric.

In Malaysian and certain Asian countries, snail has high market demand and popular to the local people as food. However, snail is also frequently reported as one of the worst food allergens, dominated by severe symptoms such as asthma and anaphylactic shock. Thus, the aims of this study is to determine the allergenicity of two species of edible snails; the local sea snail, Cerithidea obtusa and the freshwater snail Pomacea canaliculata. Snail extracts were prepared from the snail flesh and analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to determine their protein profiling. Allergenic proteins were detected by immunoblotting test using sera from 10 snail-allergic patients. The snails contain 31 to 34 protein fractions between 11 to >250 kDa. The prominent bands were seen at 33, 42, 74 and 250 kDa. Immunoblotting detected 15 and 16 allergenic proteins in C. obtusa and P. canaliculata, respectively. Three protein fractions at 30, 33 and 42 kDa were identified as the major allergens of C. obtusa, while six major allergens at 30, 33, 42, 74, 124 and 218 kDa were detected in P. canaliculata. Various minor allergens were also detected in both snails. This study indicated that numerous proteins of C. obtusa and P. canaliculata were allergenic. Thus, combined allergen extracts of both snails are essential to be included in diagnosis of snail allergy among local allergic patients.

The present study aims to determine the concentrations of Cd, Cu, Fe, Ni, Pb, and Zn in the different tissues of five species of tropical intertidal gastropods from Malaysia. Each of the species have organs/tissues that highly accumulated certain metals. For Cu, the mantles of Cerithidea obtusa, Pugilina cochlidium, and Murex trapa; and the digestive caeca of Thais sp. and Chicoreus capucinus highly accumulated Cu. The shells of Chi. capucinus and M. trapa, the digestive caeca of P. cochlidium, and the digestive glands of Thais sp. and Chi. capucinus highly accumulated Cd. The tentacles and the digestive caeca of Cer. obtusa and P. cochlidium, respectively, highly accumulated Zn, the digestive glands of Thais sp., Chi. capucinus, and M. trapa also highly accumulated Zn. The shells of most of the gastropods accumulated high levels of Pb and Ni. The opercula of most of the gastropods, besides the digestive glands for Thais sp., accumulated high levels of Fe. The present study on interspecific variations of ...

Multivariate analysis including correlation, multiple stepwise linear regression, and cluster analyses were applied to investigate the heavy metal concentrations (Cd, Cu, Fe, Ni, Pb, and Zn) in the different parts of bivalves and gastropods. It was also aimed to distinguish statistically the differences between the marine bivalves and the gastropods with regards to the accumulation of heavy metals in the different tissues. The different parts of four species of bivalves and four species of gastropods were obtained and analyzed for heavy metals. The multivariate analyses were then applied on the data. From the multivariate analyses conducted, there were correlations found between the soft tissues of bivalves and gastropods, but none was found between the shells and the soft tissues of most of the molluscs (except for Cerithidea obtusa and Puglina cochlidium). The significant correlations (P < 0.05) found between the soft tissues were further complemented by the multiple stepwise linear regressions where heavy metals in the total soft tissues were influenced by the accumulation in the different types of soft tissues. The present study found that the distributions of heavy metals in the different parts of molluscs were related to their feeding habits and living habitats. The statistical approaches proposed in this study are recommended for use in biomonitoring studies, since multivariate analyses can reduce the cost and time involved in identifying an effective tissue to monitor the heavy metal(s) bioavailability and contamination in tropical coastal waters.

The study area experiences the sea water influx during high tide and fresh water during rainfall, flooding season etc. The Creek area is beset mostly with dwarf mangroves on either side, aquaculture ponds, agriculture fields, saltpans etc. The Creek life is influenced by these activities either directly or indirectly throughout the year. It is an almost unexplored area and is represented with diverse fauna and flora. In observation of that, the current investigation was undertaken to study the status of bioaccumulation of heavy metals, specifically Cu, Cd, Zn, Pb, Ni and Fe in soft tissues namely, in foot, digestive caecum, total body and operculum and shells of three different species of molluscs namely Telescopium telescopium, Cerithidea obtusa and Cerithidea cingulata using the Flame Atomic Absorption Spectrophotometer. All the outcomes were expressed in μg/gram of dry weight and the end result reveals reflective amounts of heavy metals, except Cd, Pb and Ni. The statistical analysis of all in vitro studies of heavy metal concentration within and in between the matching organs of all tested species with oneway ANOVA showed significant difference except one. It can be concluded that, although molluscs provide information on the bioavailability of contaminants in ecosystems, it is hardly possible to derive any predictions of biological effects of these pollutants at the given level of exposure; such predictions are the main perspectives of biological effect monitoring.

Gastropod was one of the class from mollusca in mangrove ecosystem. Lubuk Kertang Village's mangrove forest was been converted into tourist areas, agricultural land and settlements. The purpose of this study was to analyze the structure of gastropods at Avicennia lanata, Rhizophora apiculata and Sonneratia alba. This research was conducted at Lubuk Kertang Village in February-March 2017. Gastropod were collected in 1 m × 1 m transect in mangrove. Examples of biota were taken by using shovel, then the biota was inserted into a plastic bag sample, wrote date of sampling and identified. The results showed there were 15 species Gastropods, namely Achatina fulica, Cerithidea alata, Cerithidea cingulata, Cerithidea obtusa, Chicoreus capucinus, Cymatium pileare, Ellobium aurimisdae, Ellobium aurisjudae, Littoraria melanostoma, Littoraria scabra, Murex tribulus, Nerita balteata, Nerita planospira, Pugilina cochlidium, Stramonita gradata, Telescopium telescopium and Terebralia sulcata. Diversity index ranged 1.702 to 2.165 was in medium category, Similarity index ranged 0.676 to 0.799 was in low category and Dominance index ranged 0.142 to 0.282 that categorized was low. The highest gastropod density was 31 individuals/m2 in the Sonneratia alba. The conclusion of the research is the existing mangrove ecosystem in Lubuk Kertang Village in a stable state.

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. 2 b. Adams, 1855: 83. Sowerby, 1866: sp. 4, pl. 1, fig. 4 a, 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), 2 H. Hamli et al., 2013: 412 –418, fig. 2 a. 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, 1897 a: 186 –187; pl. 9, fig. 22; pl. 10, fig. 5 (head). von Martens, 1897 b: 266. Fischer & Dautzenberg, 1904: 416. Oostingh, 1923: 76 –77, fig. 12. Dautzenberg, 1929: 489. Cerithium (Cerithidea) obtusum — Kobelt, 1890 a: 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. 5 C. 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. 12 a–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 (1942 a, 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 (1942 b) 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 HE 680209 –680219, AM 932765. 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 (1897 a, 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 /m 2 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. 4 a, 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., Published as part of Reid, David G., 2014, The genus Cerithidea Swainson, 1840 (Gastropoda: Potamididae) in the Indo-West Pacific region, pp. 1-65 in Zootaxa 3775 (1) on pages 27-31, DOI: 10.11646/zootaxa.3775.1.1, http://zenodo.org/record/285731, {"references":["Lamarck, J. B. P. A. de (1822) Histoire Naturelle de Animaux sans Vertebres. Vols 6 (2), 7. Paris, 232 pp., 711 pp.","Kiener, L. - C. (1841 - 1842) Genre Cerite. (Cerithium, Adanson.) In: Kiener, L. - C. (Ed.), Species General et Iconographie des Coquilles Vivantes. Rousseau & Bailliere, Paris, 104 pp.","Hombron, J. B. & Jacquinot, H. (1848) Atlas d'Histoire Naturelle Zoologie par MM. Hombron et Jacquinot, Chirurgiens de l'Expedition. In: Jacquinot, H. (Ed.), Voyage au Pole Sud et dans l'Oceanie sur les corvettes l'Astrolabe et la Zelee. Livre 26. Gide et Cie, Paris. 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Species of the Potamididae occupy the full range of aquatic habitats and differ not only in the morphology and size of their shells but also in sperm morphology. In the past, several species were classified as Cerithiidae. Characters of the developing and the mature spermatozoa have been used to gain better insight into their taxonomy. Cerithidea obtusa (Lamarck 1822) is the most dominant brackish water gastropod of the mangrove forests in Southern Thailand. Spermatological data are scarce in this species. In order to confirm its taxonomic position within the Potamididae, euspermatogenesis and euspermatozoa are examined by transmission electron microscopy. The morphological changes during spermiogenesis such as nucleus condensation, acrosome formation and development of the midpiece are described.

Using transmission electron microscopy, paraspermatozoa of representative species of the families Cerithiidae, Potamididae, Planaxidae, Dialidae and the genusAustralaba (family position uncertain) have been examined and compared with those produced by other prosobranchs, particularly other investigated cerithiaceans. Special attention is focused on the phylogenetic importance of paraspermatozoa and euspermatozoa within the superfamily Cerithiacea. The paraspermatozoa of cerithiacean gastropods fall into two structural categories: (1) those with a ‘head’ region and a ‘tail tuft’ (number of tails and the length of the tail tuft variable — Cerithiidae, Planaxidae, Potamididae, Modulidae, Turritellidae, Campanilidae, Pleuroceridae,Obtortio, Australaba); and (2) those with an elongate, vermiform body filled with large electron-dense vesicles and up to ninety axonemes — the latter emerging as numerous short tails from the posterior half of the paraspermatozoon body (Dialidae).

The oxygen consumption of three species of Malaysian mangrove gastropods was measured in air and sea water at the temperatures commonly recorded in the mangrove. The experiments in air were carried out after the animals had regained fluid lost from the mantle due to handling. Fluid loss can have considerable effects on rate of oxygen consumption. Nerita arliculata (Gould) was found throughout the mangrove and experiences from 50 to 92% aerial exposure. It has a gill and a ratio of aerial to aquatic respiration rates of 2.7 at 28°C. 50% of the animals can survive underwater for 72 h at 28°C. The other two species, Cerithidea obtusa (Lamarck) and Cassidula aurisfelis (Brugiere) experience over 95% aerial exposure, have their mantle cavities modified as lungs and have air : water respiration rate ratios of 5.5 and 6.0, respectively. 50% can survive from 48 to 36 h underwater at 28°C. Acclimated animals have Q10's of about 1.6 in air and 1.4 in water. The respiratory physiology of the snails is compared with that of rocky shore species.

The gastropod mollusc Cerithidea obtusa was examined for its lipids and fatty acids. The non-polar lipids identified were hydrocarbons, steryl esters, triglycerides, free fatty acids and sterols. The major phospholipid was phosphatidyl choline. The predominant fatty acids were myristic, palmitic, stearic, oleic, linolenic, arachidonic and eicosapentaenoic acids. Combinations of chromatographic techniques have been employed for the qualitative and quantitative determination of the lipids and fatty acids of C. obtusa .

The intertidal gastropod, Cerithidea obtusa were obtained from Bako and Sematan (Sarawak) and Deralik (Perak) in February and December 2006. Besides the shells, the snails were dissected into six different soft tissues. The soft tissues and the shell were used for detection of heavy metals. It was found that the highest concentrations of Cu (112 - 178 I¼g/g dw) and Zn (117 – 161 I¼g/g dw) were found in the tentacle; the highest concentrations of Cd (4.41 - 5.37 µg/g dw), Pb (53.2 – 63.8 µg/g dw) and Ni (26.1 - 27.9 µg/g dw) were found in the shell. On the other hand, the highest Fe concentrations (910 - 2921 µg/g dw) were found in the operculum. The cluster analysis revealed that the accumulation of heavy metals were clustered into a few groups, where metals were found in the shell are significantly different from the other soft tissues. The multivariate statistical analyses revealed that the accumulation by the different parts were inter-related with one another. Based on the multiple linear stepwise regression analysis, it was also found that the caecum was the most influential organ in accumulation of the studied heavy metals in the total soft tissues. The results indicate the ability of C. obtusa to accumulate heavy metals in the different tissues, hence fulfilling the important criteria as a good biomonitor.