Zoological Studies 47(4): 481-494 (2008)
Taxonomy and Distribution of the Neritidae (Mollusca: Gastropoda) in
Singapore
Siong Kiat Tan1 and Reuben Clements2,3,*
Rafles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore, Singapore 117543,
Republic of Singapore
2
Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore
3
World Wide Fund for Nature-Malaysia, 49, Jalan SS23/15, 47400 Petaling Jaya Selangor, Malaysia
1
(Accepted January 3, 2008)
Siong Kiat Tan and Reuben Clements (2008) Taxonomy and distribution of the Neritidae (Mollusca:
Gastropoda) in Singapore. Zoological Studies 47(4): 481-494. Molluscs from the gastropod family Neritidae
are primarily found in marine habitats, but they are also known from brackish and freshwater systems. In
Singapore, there is a paucity of information on the diversity of Neritids in all 3 aquatic environments. Herein, we
provide taxonomic descriptions and distributional data for locally occurring Neritids. Surveys of 31 sites over
a period of 10 yr yielded a total of 19 species, of which 6 species are considered new records for Singapore.
http://zoolstud.sinica.edu.tw/Journals/47.4/481.pdf
Key words: Clithon, Estuarine, Nerita, Neritina, Snail.
G
papers on Neritids, especially in the tropics.
On the tropical island of Singapore, Neritids
are poorly represented in the malacological
literature (e.g., Tweedie 1967, Tan and Chou
2000), despite being considered one of the
more-conspicuous mollusc groups above the
waterline. In one of the irst attempts to document
,
Singapore s entire biodiversity, Chou et al. (1994)
listed only 11 species of Neritids, of which 2 were
known synonyms. The inclusion of such obsolete
names and the lack of taxonomic and distributional
data on local Neritids highlight the need for a moreaccurate account of the Neritidae in Singapore.
Herein, we report 19 species from the
family Neritidae occurring in marine and brackish
waters of Singapore. We include notes on their
taxonomy, distribution, and status in relation to
historical checklists (e.g., Purchon and Purchon
1981). This report represents part of our ongoing
efforts to revise and document the malacofauna of
Singapore.
astropods from the family Neritidae
Rafinesque, 1815 occur in marine, brackish,
and freshwater systems. Along the coast, these
herbivores usually inhabit the middle to upper
intertidal zones and are known to be gregarious.
Neritids are generally euryhaline; species from the
genus Nerita are more closely associated with the
marine environment, while species from Neritina
and Clithon prefer to inhabit brackish or freshwater
habitats.
Neritids can be extremely polymorphic as
the shells of some species possess a wide variety
of colors and patterns. As such, multiple names
have been created and many are now considered
synonyms; this situation has complicated efforts
to revise the entire family. Despite several
attempts to resolve the taxonomy of species within
the Neritidae (e.g., Mienis 1973, Vermeij 1984,
Krijnen et al. 1996, Haynes 2005), inconsistencies
still remain over the use and validity of its
representatives. Such taxonomic irregularities
have, in part, resulted in the lack of comprehensive
*To whom correspondence and reprint requests should be addressed. E-mail:clements@alumni.nus.edu.sg
481
Zoological Studies 47(4): 481-494 (2008)
482
trunks and roots, canal walls, and submerged
plant debris. Except for Nerita albicilla, Nerita
planospira, and Neritina spp., measurements of
shell heights were taken from the apex to the
anterior of the shell in line with its coiling axis,
and shell width refers to the widest distance
perpendicular to the shell height. Due to their
nearly lat or sunken apex, shell lengths for Nerita
albicilla, Nerita planospira, and Neritina spp. were
defined as the distance from the anterior edge
to the posterior end of the shell placed flat with
the aperture down, while shell width refers to the
widest point perpendicular to the shell length.
The sizes indicated represent the minimum and
maximum dimensions of our examined specimens.
Observations of the animal refer to color and
patterns (if any) on the upper part of the foot.
Synonyms in local checklists and literature
were reviewed and are discussed under
“ Remarks ”, but an attempt to provide an
exhaustive list of all known synonyms was not
MATERIALS AND METHODS
During the period of 1996 to early 2007,
monthly surveys were conducted in marine and
mangrove habitats (including monsoon canals and
drains near the coast) around Singapore (Fig. 1).
The following sites were sampled: Sarimbun (1),
Lim Chu Kang Road end (2), Kranji (3), Sungei
China (4), Tanjong Irau (5), Sungei Simpang (6),
Sungei Khatib Bongsu (7), Seletar Dam (8), Sungei
Punggol (9), Punggol (10), Pulau Ubin (11), Pulau
Ketam (12), Pasir Ris (13), Sungei Loyang (14),
Sungei Changi (15), Tanjong Changi (16), Changi
North Bay (17), Tanah Merah (18), South Changi
(19), Sungei Bedok (20), Marina East (21), Kallang
Basin (22), Marina South (23), Berlayar Canal (24),
,
Sentosa (25), Pulau Sakijang Bendera/St. John s
I. (26), Pulau Hantu (27), Pulau Semakau (28),
Pulau Salu (29), Tuas (30), and Tuas South (31).
Neritids were sampled from habitats such
as intertidal rocks, breakwaters, mangrove tree
Thailand
N
Malaysia
Borneo
Sumatra
2
1
4
3
6
5
7
8
11
9
10
12
13
15
16
14
17
20 19
18
30
22
21
A
31
24
B
23
25
0
5
10 km
C
29
27
26
Fig. 1. Distribution of sampling sites throughout Singapore: (1) Sarimbun; (2) Lim Chu Kang Road end; (3) Kranji; (4) Sungei China; (5)
Tanjong Irau; (6) Sungei Simpang; (7) Sungei Khatib Bongsu; (8) Seletar Dam; (9) Sungei Punggol; (10) Punggol; (11) Pulau Ubin; (12)
Pulau Ketam; (13) Pasir Ris; (14) Sungei Loyang; (15) Sungei Changi; (16) Tanjong Changi; (17) Changi North Bay; (18) Tanah Merah;
(19) South Changi; (20) Sungei Bedok; (21) Marina East; (22) Kallang Basin; (23) Marina South; (24) Berlayar canal; (25) Sentosa;
(26) Pulau Sakijang Bendera/St. John’s Island; (27) Pulau Hantu; (28) *Pulau Semakau; (29) Pulau Salu; (30) Tuas; (31) Tuas South.
Sampling sites mentioned in Purchon and Purchon (1981): Tanjong Penjuru (A), Labrador (B), Pulau Bukom (C), *Pulau Sudong (D),
*Rafles Light (E). * Indicates sites not visible on the map.
Tan and Clements - Neritids of Singapore
made. Nomenclature follows Abbott (1994) and
references therein. Additional nomenclatural
issues were discussed with and obtained through
personal communication with local and foreign
malacologists. Species were classified as new
records based on historical local data from Chuang
(1973), Way and Purchon (1981), Chou et al.
(1994), and Tan and Chou (2000). Sampling sites
mentioned in Purchon and Purchon (1981) that
were not surveyed in this study are as follows
(Fig. 1): Tanjong Penjuru (A), Labrador (B), Pulau
Bukom (C), Pulau Sudong (D), and Raffles Light
(E). Abbreviations used in the text are as follows:
Is., island; Sg., sungei (= river); P., pulau (= island);
SH, shell height; SL, shell length; SW, shell width;
and Tg., tanjong (= cape or projecting land mass
along the coast line). All measurements are in
mm. Voucher specimens of species sampled
from Singapore were deposited in the Zoological
Reference Collection (ZRC.MOL.002776-002807),
Rafles Museum of Biodiversity Research, National
Univ. of Singapore, Republic of Singapore.
SYSTEMATICS
Nineteen species belonging to the family
Neritidae are presently known from Singapore
and 6 are considered new records. The species
are listed as follows (* indicates a new record):
Nerita albicilla Linnaeus, 1758, Nerita articulata
Gould, 1847, Nerita chamaeleon Linnaeus, 1758,
*Nerita costata Gmelin, 1791, Nerita grayana
Recluz, 1844, Nerita histrio Linnaeus, 1758, Nerita
planospira Anton, 1839, *Nerita plicata Linnaeus,
1758, Nerita polita Linnaeus, 1758, Nerita signata
Lamarck, 1822, Nerita undata Linnaeus, 1758,
*Neritina auriculata Lamarck, 1816, *Neritina
coromandeliana (Sowerby, 1836), Neritina
cornucopia Benson, 1836, *Neritina siquijorensis
(Recluz, 1843), *Neritina sulculosa (von Martens,
1879), Neritina violacea (Gmelin, 1791), Clithon
faba (Sowerby, 1836), and Clithon oualaniensis
(Lesson, 1831).
Genus Nerita Linnaeus, 1758
Description: Shell solid, generally globular;
dorsal surface smooth, spirally ribbed or with axial
sculpturing; ventral side with large columellar
callus or parietal wall, usually sculptured with
wrinkles or small pustules; spire generally low.
Columellar edge and aperture usually dentate,
sometimes with small serrations. Operculum thick,
483
calcareous, either smooth or granose, with a peg.
Remarks: Several subgenera have been
proposed, but the placement of many species
has not been consistent in the opinions of various
authors. Subgeneric placements within the genus
Nerita were revised by Vermeij (1984), but a
subgeneric classiication is not adopted here (see
Wilson 1993, Abbott and Dance 1982).
Nerita albicilla Linnaeus, 1758
(Figs. 2-1, -2)
Material examined: SINGAPORE: SL 22-22,
SW 17-17 P. Salu (ZRC.MOL.002776); SL 21-32,
SW 18-24 Tanah Merah (ZRC.MOL.002777); SL
28-29, SW 22-22 Tanah Merah.
Description: SL 19-32, SW 15-24. Shell
sculptured with closely set rounded spiral ribs;
spire sunken. Color white with varying amounts
of black blotches and fine axial lines between
blotches, all black, or alternating black and
orangish-red spiral bands. Parietal shield pale
yellow with rounded pustules becoming smaller
near columellar teeth. Columellar edge with small
teeth on central part. Outer lip dentate with 1st
teeth at 2 ends largest. Operculum yellowish-pink
with small granules over entire surface. Animal
sand-colored with black lines.
Distribution: 11, 16-19, 23, 25-27, 29, 31, B, E.
Habitat: On rocks, breakwaters, and seawalls
in lower to middle intertidal zone.
Remarks: Spiral sculpture may be indistinct
or missing in eroded shells, which often appear as
solid black bands or patches on a white ground
color, making the shell appear rough in texture.
Nerita articulata Gould, 1847
(Figs. 2-3, -4)
Material examined: SINGAPORE: SH 25-29,
SW 25-29 Berlayar Canal (ZRC.MOL.002778); SH
30-36, SW 30-35 Sg. Punggol (ZRC.MOL.002779);
SH 27-27, SW 28-28 P. Ketam.
Description: SH 20-36, SW 21-35. Shell
sculptured with numerous raised spiral cords;
older specimens usually with finer spiral threads
between main cords. Color relatively constant;
grayish to pinkish-brown with black spiral cords.
Columellar edge with several teeth, usually 3 on
center part. Parietal wall white with yellowish
tinge, usually smooth, sometimes with slightly
raised cords at edge adjoining body whorl. Outer
lip crenulate. Operculum grayish, generally darker
Zoological Studies 47(4): 481-494 (2008)
484
on central part, granular over entire outer surface.
Animal sand-colored with black lines.
Distribution: 1-15, 17, 18, 20-22, 24, 28.
Habitat : On mangrove tree trunks and roots,
monsoon canal walls, muddy banks, and rocky
areas in or near mangroves.
Remarks: This species is often known as
Nerita balteata Reeve, 1855 in the literature or
as Nerita lineata Gmelin, 1791 (not Nerita lineata
Muller, 1774). Nerita birmanica“Philippi”was
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
Fig. 2. (1, 2) Nerita albicilla Linnaeus, 1758; (3, 4) Nerita articulata Gould, 1847; (5, 6) Nerita chamaeleon Linnaeus, 1758; (7, 8)
*Nerita costata Gmelin, 1791; (9, 10) Nerita grayana Recluz, 1844; (11, 12) Nerita histrio Linnaeus, 1758; (13, 14) Nerita planospira
Anton, 1839; (15, 16) *Nerita plicata Linnaeus, 1758; (17, 18) Nerita polita Linnaeus, 1758. * Indicates a new record for Singapore.
Tan and Clements - Neritids of Singapore
also used for this species, but according to Mienis
(1973), Philippi never described such a taxon.
Krijnen et al. (1996) considers Nerita articulata and
Nerita balteata as distinct species based on minor
conchological differences, but we provisionally
treat them as conspecifics, with Nerita articulata
being the earliest name available.
Nerita chamaeleon Linnaeus, 1758
(Figs. 2-5, -6)
Material examined: SINGAPORE: SH
25-26, SW 24-25 P. Sakijang Bendera (ZRC.
MOL.002780); SH 22-23, SW 23-23 P. Salu (ZRC.
MOL.002781); SH 22-24, SW 22-25 Tanah Merah.
Description: SH 18-28, SW 17-27. Shell with
numerous raised smooth spiral ribs and very ine
indistinct axial sculpturing; spire low. Periostracum
thin, straw-colored. Color highly variable; ranging
from black and white to a combination of 2 or more
shades of gray, brown, orange, and red in random
arrays of spiral bands, wavy blotches, or axial
bands. Parietal shield white with several small
pustules and ridges on side adjoining body whorl.
Columellar edge with 2-4 small teeth on center
part. Outer lip dentate, usually with 1 distinctly
larger tooth at upper corner. Operculum grayish
with small granules over entire outer surface.
Animal light grayish with black lines.
Distribution: 11, 16-19, 23, 25-29, 31, A-D.
Habitat : Intertidal, on rocks, breakwaters, and
seawalls.
Remarks: Very similar to Nerita histrio, but
Nerita chamaeleon can be diagnosed by the higher
spire, smoother ribs, more-distinct teeth in the
outer lip and the consistently smoother and more
regularly rounded outline of the peristome.
*Nerita costata Gmelin, 1791
(Fig. 2-7, -8)
Material examined: SINGAPORE: SH 18-20,
SW 19 Tanah Merah (ZRC.MOL.002783).
Description: SH 13-30, SW 13-31. Shell
form and color relatively consistent, sculptured
with thick, raised, widely spaced grayish-black
spiral cords; spire low. Outer lip strongly dentate,
uppermost largest. Columellar edge with 3 strong
teeth, 2nd tooth most prominent and squarish.
Parietal shield white, smooth in juveniles, coarsely
wrinkled in large individuals. Operculum pinkishgray, slightly concave, covered with granules;
lower end smooth, glossy near nucleus. Animal jet
485
black.
Distribution: 18, 28, 29.
Habitat: Boulders, rocks, seawalls, and
breakwaters in middle to high intertidal zone,
usually in crevices and hollows.
Remarks: Superficially similar to Nerita
articulata, but differs by having thick spiral cords
and a distinct aperture.
Nerita grayana Recluz, 1844
(Figs. 2-9, -10)
Material examined: SINGAPORE: SH 15-24,
SW 15-21 Seletar Dam (ZRC.MOL.002784);
SH 15-17, SW 15-17 Sg. Khatib Bongsu (ZRC.
MOL.002785); SH 20-22, SW 19-20 Lim Chu Kang
road end; SH 19-22, SW 18-20 P. Ketam; SH 24,
SW 24 Punggol.
Description: SH 8-31, SW 8-31. Shell
with well-developed thin spiral ridges and axial
sculpturing between ridges; spire relatively high.
Color purplish-brown, variably patterned with
dark dashes on spiral ribs or wavy dark axial
patches, often with 3 indistinct darker spiral bands.
Columellar edge with 3 or 4 teeth, uppermost
squarish. Parietal shield smooth to strongly
wrinkled, color varying from white with yellowish
tinge to yellow with orangish tinge. Outer lip
dentate with prominent last tooth at upper end.
Operculum grayish, usually with patchy beige
coloration, with small granules over entire surface.
Animal creamy-white.
Distribution: 1-9, 11, 12, 14, 15.
Habitat : On tree trunks and roots and among
or under rocks in interior or coastal fringes of
mangroves.
Remarks: Spire more prominent than those
of other local Nerita species. Some forms of
Nerita grayana have a superficial similarity to
Nerita undata, but the latter was not found in the
same habitat during our surveys, and the animals
rather differ. This species is also similar to Nerita
helicinoides Reeve, 1855, which Mienis (1992a)
listed as a junior synonym of Nerita guamensis
Quoy and Gaimard, 1834. Nerita guamensis is
apparently conined to the western Paciic Ocean
and has not been recorded in this region. Vermeij
(1973) mentioned the presence of Nerita striata
(probably Nerita grayana) in Singapore. However,
we were unable to find descriptions for Nerita
striata, which is usually listed as a synonym of
Nerita undata, and we therefore treat it as such.
There are a few forms of Nerita grayana among
486
Zoological Studies 47(4): 481-494 (2008)
local populations, and we may actually be looking
at a species complex. Until further studies show
otherwise, we are provisionally regarding them as
conspeciics.
Nerita histrio Linnaeus, 1758
(Figs. 2-11, -12)
Material examined: SINGAPORE: SH 21, SW
23 Sarimbun (ZRC.MOL.002790); SH 14-17, SW
15-19 Tuas South (ZRC.MOL.002791); SH 24-25,
SW 24-27 South Changi.
Description: SH 14-26, SW 15-28. Shell
sculptured with rough, unevenly raised spiral
cords, usually stronger at base of body whorl;
axial sculpturing prominent, appearing scale-like in
uneroded specimens; spire low to nearly lat. Color
and markings variable; white or light yellow to gray
and orange with random patterns of dark blotches,
axial patches, or spiral bands. Few small obsolete
teeth at center of columellar edge, sometimes with
reddish stain around parietal teeth in juveniles.
Parietal shield white or pale yellow, smooth or
with small wrinkles. Outer lip with small teeth.
Operculum flesh-colored, granulate, somewhat
convex, sometimes with varying degrees of dark
blotches. Animal sand-colored with black lines.
Distribution: 1, 11, 13, 14, 16-20, 22, 23,
25-27, 31.
Habitat: On mangrove tree trunks and
stilt roots; muddy rocks at coastal fringes of
mangroves; among rocky rubble along edge of
muddy sand lats; on breakwater rocks.
Remarks: This species when found in
mangroves appears to be rather drab (usually
white with some black markings) compared to
those found along the open sea. We speculate
that this phenomenon may be driven by
environmental factors, but further studies are
required to conirm this. Usually known as Nerita
squamulata Le Guillou, 1841 (e.g., Springsteen
and Leobrera 1986, Tan and Chou 2000), Nerita
histrio was treated by Mienis (2004) as a senior
synonym and a igure of a specimen illustrated in
Rumphius (1705: plate 22, Fig. 5) was proposed
as the lectotype.
Nerita planospira Anton, 1839
(Figs. 2-13, -14)
Material examined: SINGAPORE: SL 20-24,
SW 16-20 Marina East (ZRC.MOL.002786); SL
28-29, SW 21-22 P. Ubin (ZRC.MOL.002787), SL
26-28, SW 20-22 Pasir Ris.
Description: SH 18-27, SW 18-30. Shell
sculptured with raised spiral ridges and smaller
cords between primary ones; spire sunken.
Periostracum thin, brown. Color pink with
somewhat axially aligned dark-violet patches and
bands. Aperture light beige to white, peristome
black with a black blotch at parietal shield
edge. Four or 5 teeth present on columellar
edge extending over 1/2 of septum as folds
and pustules. Outer lip with very fine indistinct
serrations. Dark gray to blackish operculum,
entirely smooth and glossy. Animal black.
Distribution: 1-3, 11-13, 15, 21, A.
Habitat : On mangrove tree trunks and roots,
muddy rocks, trash (e.g., discarded rubber tires
and wooden planks), and monsoon canal walls.
Remarks: This species was tentatively
identified as Nerita sp. in Lim (1963), and the
Nerita plancapira mentioned in Chou et al. (1994)
is probably a typographical error.
*Nerita plicata Linnaeus, 1758
(Figs. 2-15, -16)
Material examined: AUSTRALIA: SH 21-23,
SW 20-22 Langford Is., Queensland; SH 22-27,
SW 23-25 Dirk Hartog Is., western Australia.
INDONESIA: SH 16-21, SW 16-21 Bali; SH
21-24, SW 22-25 Baron, south-central Java; SH
20-21, SW 18-20 Kabaena, southeast Sulawesi.
PHILIPPINES: SH 12-24, SW 12-23 Sulu
Archipelago.
Description: SH 15-21, SW 16-21. Shell
with numerous widely spaced, regularly rounded
spiral cords; spire low to moderately high. Color
consistently pale creamy-pinkish, ribs sometimes
with a darker tone or black markings. Columellar
edge with 3 or more strong squarish teeth. Parietal
shield white, wrinkled. Outer lip bordered by a
yellow line, strongly dentate, teeth at both ends
most prominent. Operculum pink, concave, glossy,
smooth, inely granulated along border. Animal not
observed.
Distribution: 28.
Habitat: Observed in holes and crevices in
rocks, boulders, hollows, and crevices around
supralittoral zone of sandstone and limestone
boulders, and cliffs facing the open surf of Pulau
Langkawi, Malaysia and in Java, Indonesia.
Remarks: This species has a wide IndoPaciic distribution and is generally restricted to the
high intertidal zone. Interestingly, Mienis (1992b)
Tan and Clements - Neritids of Singapore
noted that this species reached the Galapagos
Islands by hitchhiking on transoceanic vessels.
Nerita polita Linnaeus, 1758
(Figs. 2-17, -18)
Material examined: SINGAPORE: SH 19-22,
SW 20-24 Sentosa (ZRC.MOL.002788); SH 15-21,
SW 15-22 South Changi (ZRC.MOL.002789); SH
37, SW 38 Sg. Bedok; SH 19-20, SW 20-21 South
Changi.
Description: SH 15-36, SW 17-40. Shell
generally smooth without raised spiral cords or
other prominent sculpturing, sometimes with fine
spiral grooves in juveniles, larger specimens
usually with fine axial striae; spire very low,
sometimes nearly flat. Color highly variable;
markings including shades of white, gray, brown,
orange, and red, zigzag markings, spiral or
axial bands, or blotches with specks and dots.
Columellar edge with a few fine teeth at center
extending into small ridges on parietal shield,
which is otherwise smooth, glossy. Aperture white
or with some yellow around edges. Outer lip with
fine obsolete crenulations. Operculum greenishgray, smooth, glossy except for fine transverse
lines along border. Animal yellowish with black
lines.
Distribution: 19, 20, 25, 26, 30, B.
Habitat: Intertidal rocks. Nocturnal in habit
and frequently found shallowly buried in sand
against base of rocks during the day.
Remarks: All examined shells found locally
belong to what was formerly known as Nerita
polita form rumphii (e.g., Abbott and Dance 1982),
which is now often referred to as Nerita litterata.
Krijnen et al. (1999) regarded Nerita litterata as
a valid species in the Nerita polita complex, and
the main conchological differences with Nerita
polita are its generally smaller size, the flat to
concave parietal area, and fine spiral striae
that are obvious in smaller shells but obsolete
in larger shells. However, both shell forms are
often barely distinguishable, and forms of both
Nerita litterata and Nerita polita were observed
occurring sympatrically among the same boulders
at Teluk Burau in Langkawi, West Malaysia. This
suggests that they are polymorphic variations of
a single species. We are provisionally treating
Nerita litterata as a form of Nerita polita, and
further studies on both of these closely related
species are required to determine their actual
relationships within the Nerita polita complex.
487
Another commonly used taxon, Nerita doreyana,
is a junior synonym of Nerita litterata according
to Krijnen (1999). Species in the Nerita polita
group are often incorrectly placed in the subgenus
Amphinerita (e.g., Dharma 2005), which has a
granulated operculum as one of its characteristics
(Mienis 2000b).
Nerita signata Lamarck, 1822
(Figs. 3-19, -20)
Material examined: INDONESIA: SH 18-18,
SW 17-18 P. Semata, Maluku; SH 15-16, SW 16
Lampung, Sumatra. PHILIPPINES: SH 13, SW
13 Olango Is., Cebu; SH 15-18, SW 15-20 Manila
Bay, Luzon.
Description: SH 15-18, SW 16-18. Shell
sculptured with spiral cords crossed by axial
sculpturing, appearing scaly in uneroded shells;
spire low. Color and markings variable; white
to brown with black or brown maculations.
Columellar edge with several small teeth in center
extending into small ridges. Parietal shield with
distinct reddish-brown blotch from parietal teeth
extending to upper part. Aperture white. Outer lip
dentate. Operculum slightly convex, pinkish-lesh
color, minutely granulated. Animal not observed.
Distribution: E.
Habitat : On intertidal rocks under shade.
Remarks: Recorded as Nerita reticulata
Karsten, 1789 in Way and Purchon (1981), but
,
this name should not be used as Karsten s nonbinomial work (Museum Lekeanum) has been
suppressed by the ICZN (Opinion 1877; ICZN
1997) for nomenclatural reasons (Mienis 2000c).
Nerita undata Linnaeus, 1758
(Figs. 3-21, -22)
Material examined: SINGAPORE: SH 28-29,
SW 26-27 P. Salu (ZRC.MOL.002792); SH 15-33,
SW 14-29 South Changi (ZRC.MOL.002793); SH
29-30, SW 27-28 South Changi; SH 14-16, SW
13-16 Sg. Bedok (ZRC.MOL.002794); SH 29-30,
SW 27-28 P. Hantu.
Description: SH 17-37, SW 16-38. Shell
spirally sculptured with numerous low rounded
ribs; spire moderately high. Color variable; white
to light brown with varying amounts of random
black blotches, stripes, or axial bands, often with 3
indistinct darker spiral bands, sometimes all black.
Parietal shield wrinkled, white with varying degrees
of yellow staining around aperture. Columellar
Zoological Studies 47(4): 481-494 (2008)
488
edge with 3-5 teeth, uppermost 1 squarish. Outer
lip dentate with a distinctly larger tooth at upper
end. Operculum lat, gray with small granules over
entire outer surface. Animal gray with black lines.
Distribution: 11, 16-20, 23, 25-27, 29-31, B, E.
Habitat: In crevices and under rocks of
breakwaters and rocky shores of middle to upper
intertidal zones. Nocturnal, emerging from their
hiding places at dusk.
Remarks: There are many known synonyms
(19)
(20)
(21)
(22)
(23)
(24)
(25)
(26)
(27)
(28)
(29)
(30)
(31)
(32)
(33)
(34)
(35)
(36)
(37)
(38)
Fig. 3. (19, 20) Nerita signata Lamarck, 1822; (21, 22) Nerita undata Linnaeus, 1758; (23, 24) *Neritina auriculata Lamarck, 1816; (25,
26) *Neritina coromandeliana (Sowerby, 1836); (27, 28) Neritina cornucopia Benson, 1836; (29, 30) *Neritina siquijorensis (Recluz,
1843); (31, 32) *Neritina sulculosa (von Martens, 1879); (33, 34) Neritina violacea (Gmelin, 1791); (35, 36) Clithon faba (Sowerby,
1836); (37, 38) Clithon oualaniensis (Lesson, 1831). * Indicates a new record for Singapore.
Tan and Clements - Neritids of Singapore
(e.g., Nerita quadricolor Gmelin, 1791; Nerita
striata Burrow, 1815; and Nerita longii Recluz,
1842), and several have been consistently treated
as valid species in recent work (e.g., Krijnen et
al. 1997 2001). Although Neritids are known to
be polymorphic, the presence of cryptic species
is highly likely within the Nerita undata complex.
Local populations do not show clear intraspecific
variation and probably consist of a single species.
Krijnen et al. (2006) stabilized the taxonomical
status of Nerita undata with the designation of
a neotype, which agrees with the description of
shells examined in this study.
Genus Neritina Lamarck, 1816
Description: Shells cap-shaped, globular, or
semiglobose, generally thinner than shells of Nerita
spp.; surface generally smooth. Columellar edge
smooth or with fine denticulations. Operculum
smooth with thin horn border.
Remarks: Many genera and subgenera have
been designated mainly based on shell form, but
much confusion still remains regarding respective
specific placements and the validity of some of
the generic and subgeneric names. We concur
with the opinion of Haynes (2005) in regarding the
division of Neritina into various subgenera (e.g.
Neripteron, Neritona, and Vittina) as unnecessary
and unjustiiable based on shell shape and radular
differences.
*Neritina auriculata Lamarck, 1816
(Figs. 3-23, -24)
Material examined: SINGAPORE: SL 8-13,
SW 6-9 Berlayar Canal (ZRC.MOL.002795); SL
9-13, SW 7-10 Sg. Punggol (ZRC.MOL.002796);
SL 13, SW 10 Sg. Punggol.
Description: SL 8-13, SW 6-10. Shell
semiglobular or bean-shaped; spire sunken.
Greenish-brown with darker brown, violet
reticulations or lames. Aperture large, surrounded
by a broad peristome ending in a point on upper
columellar side, sometimes with slight protrusion
at lower end. Operculum with reddish horn border.
Animal black.
Distribution: 9, 24.
Habitat : On stones submerged in mangrove
streams in running water.
Remarks: Local shells were not found
to have the large extended“wings”or“ ears”
seen on some specimens from Indonesia and
Peninsula Malaysia. Considerable variation in
489
the development of the“ears”was noted by van
Benthem Jutting (1956). This species is easily
mistaken for juvenile shells of Neritina cornucopia,
to which it bears a strong resemblance, and
juveniles can be difficult to identify with certainty.
Neripteron is usually used for this species, either
with full generic status or as a subgenus of Neritina
(e.g., Komatsu 1986, Swennen et al. 2001).
Dharma (2005) placed this species in the genus
Clypeolum.
*Neritina coromandeliana (Sowerby, 1836)
(Figs. 3-25, -26)
Material examined: INDONESIA: SH 19-28,
SW 17-24 Tg. Berlangkap, P. Bintan, Riau,
Sumatra (ZRC.MOL.002797). SINGAPORE: SH
15, SW 13 Marina East.
Description: SH 15, SW 13. Shell smooth,
somewhat conoidal; spire moderately elevated.
Pinkish with black stripes, appearing brown with
black stripes if periostracum intact. Parietal region
grayish-white, smooth with tiny dentition at center
of columellar edge. Operculum smooth, grayishbrown with reddish horn border. Animal not
observed.
Distribution: 21.
Habitat: In seepholes of small tributary
drains of monsoon canals. This species has
been observed on fallen leaves and branches
submerged in stagnant pools in mangroves of
Pulau Bintan, Riau, Indonesia, and on submerged
trunks of Nipah palms in Pahang, W. Malaysia.
Remarks: This species has often been
confused with Neritina zigzag Lamarck (Brandt,
1974). As such, it is likely that the Neritina zigzag
mentioned in van Benthem Jutting (1956) and
Way and Purchon (1981) referred to this species.
This species has also been placed in many
different genera and subgenera, e.g., Neritina
(Vittoida) coromandeliana (Brandt 1974); Neritina
(Provittoida) coromandeliana (Springsteen and
Leobrera 1986); and Vittina coromandeliana
(Swennen et al. 2001). Vittina (Provittoida)
paralella/Neritina (Vittina) parallela in a number of
Japanese publications (e.g., Komatsu 1986) is a
misidentiication of this species (Mienis 2000a).
Neritina cornucopia Benson, 1836
(Figs. 3-27, -28)
Material examined: SINGAPORE: SL 11-24,
SW 9-18 Marina East (ZRC.MOL.002798); SL
490
Zoological Studies 47(4): 481-494 (2008)
19-21, SW 14-15 Marina East; SL 12-16, SW 9-12
Sg. Punggol (ZRC.MOL.002799); SL 13-16, SW
9-10 Berlayar Canal; SL 12-13, SW 9-10 Punggol.
Description: 9-24, SW 6-17. Depressed
shell with rapidly expanding body whorl, nearly
symmetrical when viewed from dorsum; spire
sunken. Color white with purplish axial lines and
“tent”markings, spiral bands often devoid of
markings. Periostracum usually covering dorsum,
brown, with algae or silt. Peristome ovate,
continuous. Parietal shield and aperture white
with grayish shades or very dark gray throughout.
Small whitish denticulations along edge of
columellar, usually along entire length. Operculum
color similar to parietal area with an orangish-red
horn border. Animal black.
Distribution: 1-3, 7, 9-11, 13, 15, 21, 24.
Habitat : Usually submerged; on mud, plant
matter (e.g., fallen leaves and braches in stagnant
pools), on and under stones in streams, and on
concrete banks of drains.
Remarks: Very similar to Neritina violacea
in terms of shell shape and is usually considered
a variation of Neritina violacea (e.g., Ng et al.
1999b), but our study of conchological characters
of the collected material largely agree with that of
Huang (1997), and we are provisionally regarding
the 2 species as distinct due to the different ventral
colors.
*Neritina siquijorensis (Recluz, 1843)
(Figs. 3-29, -30)
Material examined: SINGAPORE: SL 5-7, SW
4-6 Pasir Ris (ZRC.MOL.002800); SL 9-11, SW 6-7
Sg. Bedok; SL 6-6, SW 5-5 Pasir Ris.
Description: SL 5-7, SW 4-6. Shell smooth
with very fine axial striae; spire very low or flat.
Periostracum thin, brownish. Color purplish with
white tongue-shaped patterns and darker-toned
shading somewhat aligned in a spiral pattern.
Parietal shield grayish with 4-6 small teeth at
center of columellar edge. Operculum smooth,
gray with a reddish horn border. Animal not
observed.
Distribution: 13, 20.
Habitat : On submerged fallen leaves in pools
and stones on mudlats.
Remarks: Neritina guerini is a very similar
species and could be conspecific (T. Eichhorst
pers. comm.), but we have been unable to
verify this due to a lack of available references
for Neritina guerini. It was placed in the genus
Puperita by Dharma (2005).
*Neritina sulculosa (von Martens, 1879)
(Figs. 3-31, -32)
Material examined: SINGAPORE: SL 8, SW 6
Berlayar Canal (ZRC.MOL.002801); SL 12, SW 8
Sg. Punggol.
Description: SL 8-12, SW 6-8. Shell with very
fine spiral striae; body whorl rapidly expanding;
spire low. Periostracum olive-green. Peristome
large, ovate, continuous, somewhat ridge-like
where it meets body whorl. Parietal region light
gray to brown, finely textured on parietal shield.
Operculum smooth, dark gray, darker centrally with
a red horn border. Animal not observed.
Distribution: 9, 24.
Habitat: In mangrove streams, on stones
submerged in running water.
Remarks: Apparently rare, this species was
not featured in our available references and was
positively identiied by Henk Mienis.
Neritina violacea (Gmelin, 1791)
(Figs. 3-33, -34)
Material examined: SINGAPORE: SL 18-27,
SW 13-20 Marina East (ZRC.MOL.002802); SL
24-25, SW 18-18 Marina East; SL 11-16, SW 9-13
Sg. Punggol (ZRC.MOL.002803).
Description: SL 11-26, SW 9-20. Depressed
shell; body whorl rapidly expanding, nearly
symmetrical when viewed from dorsum; spire
sunken. Color white with dark-purplish often solidly
banded axial bands and coarse "tent" markings.
Periostracum brown, usually covered with silt or
algae. Peristome ovate, continuous. Parietal
shield and aperture color varying from whitish with
orange tinge to brick-red. Denticulations along
columellar edge variable, often only in central part,
sometimes nonexistent. Operculum smooth; color
similar to parietal area, usually darker with varying
numbers of dark blotches. Animal orange with
some black patches.
Distribution: 1-4, 6-13, 15, 21, 24.
Habitat: Similar to that of Neritina cornucopia.
Remarks: Shell very similar to that of Neritina
cornucopia, mainly differing in having an orangishred parietal region, lacking the spiral bands that
are sometimes seen in Neritina cornucopia, and
generally attaining a larger size. A well-known
synonym, Neritina crepidularia, was listed in Chou
et al. (1994). Dostia is usually used as the genus
Tan and Clements - Neritids of Singapore
or subgenus for this species (e.g., Hill 1977,
Haynes 2001), but some authors (e.g., Swennen
et al. 2001) place this under Neripteron.
Genus Clithon Montfort, 1810
Description: Subglobose shells similar to
some Neritina spp., generally roughened with
wrinkles, ridges, or spines. Columellar edge with
a large tooth, followed by smaller teeth on central
part. Operculum smooth with a narrow horn
border and curved ridge; indentation occurring
where large tooth of columellar edge its.
Remarks: Smooth glossy shells within this
genus are often placed in the separate subgenus,
Pictoneritina.
Clithon faba (Sowerby, 1836)
(Figs. 5-35, -36)
Material examined: SINGAPORE: SH 10-19,
SW 10-17 Marina East (ZRC.MOL.002804); SH
9-16, SW 9-15 Sg. Bedok (ZRC.MOL.002805); SH
11, SW 11 Punggol; SH 14-17, SW 14-17 Berlayar.
Description: SH 11-19, SW 11-17. Shell
smooth; body whorl either regularly round, or
possessing an angular“ shoulder”with a slight
concavity beyond suture; spire low to turreted.
Color variable; pale yellow, yellowish-green, very
dark green, pink, or gray with variable patterns of
reddish to whitish, black-shaded spots, zigzag or
triangular-shaped markings, usually with darker
indistinct spiral bands, but spiral bands of large
blotches or bands not uncommon. Periostracum
greenish-brown. Parietal shield thick, white to
grayish with a single large tooth, 5-7 smaller
sometimes obsolete teeth on central part of
columellar edge. Operculum smooth, yellow to
grayish with a red horn border. Animal yellowish
with white lines and lecks.
Distribution: 7, 10, 20-22, 24.
Habitat: On sandy banks of mangrove
streams, on sand, stones, and concrete surfaces
of drains and canals near sea.
Remarks: Two specimens collected from P.
Bintan, Indonesia were found to have a single
protruding spine on the edge of the "shoulder".
Apart from the presence of the spines, all other
conchological aspects agree with the specimens
from Singapore, which is incidentally the type
locality of the species. Van Benthem Jutting (1956)
remarked that Clithon faba is never ornamented
with spines and C. faba from Singapore was
indeed never found with spines. Brandt (1974)
491
remarked that C. faba of van Benthem Jutting is
not this species, but he does not justify his claims.
Clithon oualaniensis (Lesson, 1831)
(Figs. 3-37, -38)
Material examined: SINGAPORE: SH 4-11,
SW 4-10 Kallang Basin (ZRC.MOL.002806); SH
6-11, SW 6-10 Sg. Bedok (ZRC.MOL.002807).
Description: SH 5-10, SW 5-9. Shell smooth,
glossy; spire low or conical, appearing increasingly
conical in larger shells. Color generally yellow or
greenish with highly variable patterns of triangular
markings, zigzag lines, spiral bands, and axial
lines. Parietal shield relatively small, yellow
or white with a larger tooth and ~4 min teeth
at columellar edge. Operculum greenish-gray,
somewhat lighter at edge with a red horn border.
Animal greenish-gray with black lines.
Distribution: 1, 10, 11, 13, 15, 17-22, 31.
Habitat: On sandy banks of mangrove
streams, on sand in drains and canals, intertidal
muddy sand banks, and on mud in mangroves.
Remarks: Unmistakable colorful glossy
little shells. Grüneberg (1978 1982) studied
the shell color and pattern variations in several
populations of this species and found that its axial
and spiral patterns were not entirely discontinuous
among individuals and used the term“pseudopolymorphism”for this category of variation.
DISCUSSION
Neritids typically found in brackish waters
include Nerita articulata, Nerita grayana, and
Nerita planospira. These species usually occur
in mangroves along the northern coastline (e.g.,
Sarimbun and Sg. Simpang). From our sampling
results, Nerita grayana appears to be largely
confined to the Johor Straits, while the other
2 species have been found or reported from
other locations further south. Nerita planospira
was often associated with trunks and roots of
Rhizophora trees, but further studies are needed
to elucidate potential habitat affinities. Nerita
planospira appears to be moderately uncommon
and occurs in relatively low densities. The largest
local population of Nerita planospira appears to be
located in the mangroves of P. Ubin. It was also
reported by Way and Purchon (1981) to occur at
Tg. Penjuru, which is incidentally the last remaining
extensive mangrove forest of the southern
coastline, but that location was not sampled in this
492
Zoological Studies 47(4): 481-494 (2008)
study. The most widely distributed local species
is probably Nerita articulata, a species commonly
sighted on monsoon canal walls and mangrove
trees, sometimes numbering in the hundreds in
a single location and which was found in more
than 70% of the sampling sites. Although Nerita
articulata has been found on breakwater rocks
and seawalls facing the open coast (e.g., Tanah
Merah), individuals attain a much smaller average
adult size and never reach the abundance levels of
populations in mangroves.
All of the 8 local Neritina species appear
to be restricted to brackish habitats. Although
many freshwater species of Neritina are known
throughout Southeast Asia, no true freshwater
species have been found in Singapore. From
our observations, Neritina auriculata, Neritina
cornucopia, Neritina sulculosa, and Neritina
violacea were found sympatrically on stones in
streams of Sungei Punggol and Berlayar Canal.
Neritina auriculata and Neritina sulculosa appear
to have a preference for running water, as neither
species has been found in stagnant pools or mud
banks (e.g., Sarimbun and Kranji), where the other
2 species have been found. Among the Neritina
species sampled, Neritina coromandeliana was the
rarest with only a single specimen found at Marina
East. Subsequent trips to the same location
did not yield more samples and unfortunately,
construction activities have destroyed and altered
much of the original sampling location. Neritina
siquijorensis has only been found in Pasir Ris and
Sungei Bedok, but it may have been overlooked
by earlier workers due to its small size. It would
not be surprising if increased sampling efforts
reveal the occurrence of this species at other
locations. Local Clithon species are common in
brackish canals and drains near the coast, and
can also be found in muddy sand areas of lagoons
and estuarine areas with little tidal influence.
Both species were found on the sandy banks of
a creek in a mangrove forest at Punggol. Clithon
faba seems to prefer a sandier substratum and
is probably more conined to brackish conditions.
This species was not found on slightly muddy
intertidal sand lats, nor did it occur on mud among
mangroves where Clithon oualaniensis occurs.
Eight species of Neritids are typically
associated with marine environments. Nerita
albicilla, Nerita chamaeleon, Nerita costata,
Nerita polita, and Nerita undata are generally
found on rocky shores and breakwaters directly
facing the surf (e.g., Tg. Changi and Tanah
Merah). Although Nerita histrio is often found
sympatrically, it probably favors a slightly muddier
habitat and usually occurs near estuaries (e.g.,
Sungei Bedok), or on muddy sand and rocks of
lagoons (e.g., Tanah Merah and Pulau Sakijang
Bendera). Two other marine species, Nerita
plicata and Nerita signata, are known to occur
in Singapore but were not found in our surveys.
Nevertheless, they were included in this study and
described based on specimens from Indonesia
and Malaysia. Nerita signata (as Nerita reticulata
in Way and Purchon 1981) was collected from
Raffles Light Ecirca 1950-1960 (Purchon and
Purchon, 1981). Some juveniles of Nerita histrio
bear a strong resemblance to Nerita signata,
which begs the question of whether it could have
been a misidentification. It also seems suspect
that Nerita histrio, a common species in local
waters, was not listed by Way and Purchon (1981).
However, another reason for Nerita histrio not
being listed may be the lumping of this species
with that of another notoriously similar species:
Nerita chamaeleon. As the geographical position
of Singapore is within the known distribution
range of Nerita signata, the occurrence of this
species is provisionally treated as valid until
proven otherwise. Although Nerita plicata was
not found in our surveys, we came across a single
lot of 7 specimens of Nerita plicata from a private
collection. The shells were collected around the
late 1970s and early 1980s from Pulau Semakau,
which is an island within the geographical
boundaries of Singapore. Since this species
was not recorded in the literature to occur in local
waters, we consider this species a new record for
Singapore.
CONCLUSIONS
In total, 19 Neritid species were recorded
from the waters of Singapore. Overall, 8 species
are usually associated with marine habitats,
while 11 are typically found in mangrove/brackish
waters. Two marine and 4 brackish water species
were recorded for the 1st time, comprising
nearly 30% of the total number of sampled
species. All the sampled species are believed
to be native because Singapore is within their
known geographical distribution range. The high
proportion of new records may be attributed to
the lack of taxonomical work and undersampling
of the local malacofauna, which was evident
throughout the available literature. Future surveys,
particularly of other locations not covered in this
Tan and Clements - Neritids of Singapore
study may reveal species yet to be recorded and
increase the distribution ranges of known species.
Observations have shown that local Neritids do not
appear to be under threat from exotic species or
collection. Although major reclamation works over
the past few decades have drastically changed the
coastal environments of Singapore, populations
of most marine Neritids do not appear to be under
threat and have rapidly colonized artiicial habitats
such as breakwaters and seawalls. Increased
habitat alteration, however, may have a disastrous
effect on resident populations of Neritina auriculata,
Neritina coromandeliana, and Neritina sulculosa
as they appear restricted to certain niches within
their sampled localities. As such, the conservation
of remaining coastal habitats may be vital to the
survival of these species in Singapore.
Acknowledgments: We thank H. Mienis for
graciously imparting his taxonomic knowledge
on Neritids and help with obtaining references,
T. von Rintelen for photographs of the Neritid
syntypes, and T. Eichhorst for his many interesting
discussions. We are also greatly indebted to S.Y.
Chan, H.E. Ng, L. Nguang, and R. Tan for their
material and assistance. Finally, we are grateful
to the 2 anonymous referees whose comments
greatly improved the manuscript.
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