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NATURE IN SINGAPORE 2013 6: 257–263 Date of Publication: 5 November 2013

© National University of Singapore

SINGAPORE MOLLUSCA: 3. THE FAMILY DONACIDAE

(BIVALVIA: VENEROIDA: TELLINOIDEA)

Siong Kiat Tan* and Martyn E. Y Low

Raffles Museum of Biodiversity Research, National University of Singapore

6 Science Drive 2, Singapore 117546, Republic of Singapore

(*Corresponding author: dbstsk@nus.edu.sg)

ABSTRACT. — The family Donacidae in Singapore is reviewed, and the occurrence of two species, Donax (Latona)

cuneata and Donax (Latona) faba, is confirmed. Donax pallidus, which was first described from Singapore, is regarded

to be a junior subjective synonym of Donax (Latona) faba based on examination of photographs of a syntype and

topotypic material.

KEY WORDS. — Mollusca, Donacidae, Donax, Latona, taxonomy, synonymy, records, Singapore

INTRODUCTION

The family Donacidae Fleming, 1828, is large family of about 100 recognised species found worldwide in warm waters

(Huber, 2010). These clams generally live shallowly-buried just under the surface of wave-swept parts of beaches in the

intertidal zone. Wave action often flushes the animals out, which they then move with the wash before quickly

reburying themselves with their strong foot (K. S. Tan & Chou, 2000).

In Singapore, donacids are abundant in some places where they occur and are sometimes collected for food. Being

brightly and variably coloured, shells of donacids are quite attractive. Freshly dead articulate shells are usually widely

splayed open, somewhat reminiscent of butterflies (Fig. 1). Empty shells sometimes occur in large numbers along the

strandline of some beaches, where beachgoers have often been seen to delight in making a small collection of them.

Fig. 1. Donax (Latona) faba Gmelin, 1791, at Changi East Bay (Red Cliff Shoal; see Fig. 2 for location) showing the colourful,

freshly-dead, articulate shells which are widely splayed open, and resemble butterflies. (Photograph by: S. K. Tan).

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Herein, we report on the donacids from Singapore with descriptions and notes on their taxonomy, nomenclature, and

local distribution. Details of records in the literature, and other notes of interest are also included. Two species of

donacids, namely Donax (Latona) cuneata Linnaeus, 1758 and Donax (Latona) faba Gmelin, 1791, have been recorded

from Singapore. Donax pallidus (Gould, 1850; type locality: Singapore) is herein identified as a junior subjective

synonym of Donax faba Gmelin, 1791.

MATERIAL AND METHODS

Relevant literature on the taxonomy of the family Donacidae was reviewed. Records of the species of the family

Donacidae were compiled from a review of published literature. Primary synonyms and records mentioning Singapore

are listed. Material from various collections were also examined. Abbreviations used for collections are: ZRC =

Zoological Reference Collection of the Raffles Museum of Biodiversity Research, National University of Singapore;

and TSK = collection of the first author. Other abbreviations used: Measurements are given in the form of shell height

(SH) × shell length (SL). Shell height is defined as the distance from the highest part of the dorsal side to the lowest part

of the basal edge, and shell length is the perpendicular distance between the anterior and posterior ends. All

measurements are in millimetres (mm).

SYSTEMATIC ACCOUNTS

SUPERFAMILY TELLINOIDEA BLAINVILLE, 1814

FAMILY DONACIDAE FLEMING, 1828

Donacidae Fleming, 1828: 433 (type genus Donax Linnaeus, 1758).

Genus Donax Linnaeus, 1758

Donax Linnaeus, 1758: 682 (type species Donax rugosus Linnaeus, 1758, by subsequent designation by Anton, 1838: 3;

gender feminine).

Remarks. — The gender of Donax is regarded as feminine based on the names originally included by Linnaeus (e.g.,

rugosa, denticulata, scripta).

Subgenus Latona Schumacher, 1817

Latona Scumacher, 1817: 156 (type species Donax cuneata Linnaeus, 1758, by subsequent designation in Opinion 1057

[ICZN, 1976: 19]; gender feminine).

Remarks. — The genus-group name Latona Schumacher, 1817, was placed on the Official List of Names in Zoology in

Opinion 1057 (ICZN, 1976: 19). As the name is in current usage for a genus or subgenus of bivalve molluscs, all later

uses of the genus-group name Latona are unavailable junior homonyms. This includes the cladoceran genus-group

Latona Strauss, 1820, which is also in current use for the group of crustaceans (e.g., Korosi & Smol, 2012).

Donax (Latona) cuneata Linnaeus, 1758

(Figs. 2, 3)

Donax cuneata Linnaeus, 1758: 683, no. 87 (type locality: none).

Singapore records:

Donax sp. – Traill, 1847: 239; K. S. Tan & Chou, 2000: 147 [in part; bottom two shells in upper figure].

Donax cuneatus – S. K. Tan & Woo, 2010: 16; Wang et al., 2011: 295.

Material examined. — Singapore: Tanah Merah Ferry Terminal (TSK 22809), 22 Apr.2001; East Coast Park, just east

of Sungei Bedok (TSK), 13 Nov.2005.

Distribution in Singapore. — See Fig. 2.

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Fig. 2. Distribution of the family Donacidae Fleming, 1828, in Singapore: , Donax (Latona) cuneata Linnaeus, 1758; and ,

Donax (Latona) faba Gmelin, 1791. Solid symbols represent records based on material examined, while open symbols represent

records from both published literature and unpublished data. Abbreviations used: BE, Bedok; CH1, Changi East Bay (Red Cliff

Shoal); CH2, Changi (carpark 7 area); CH3, Changi; CP, Changi Point Beach; EC1 (East Coast Park, just east of Sungei Bedok);

EC2, East Coast Park (Katong area); ME, Marina East; NS, National Service Resort and Country Club; SI, Siglap; TM, Tanah Merah

Ferry Terminal; PT, Pulau Tekukor (east side).

Habitat. — Intertidal, shallowly buried in sand of exposed sandy beaches, migrating up and down between the high and

low tide marks following the ebb and flow of the tide (Poutiers, 1998; K. S. Tan & Chou, 2000; pers. obs.).

Diagnosis. — The following diagnosis is based on specimens from Singapore and Swennen et al. (2001). Shell solid,

compressed, distinctly inequilateral, trigonal-ovate in outline, to about 35 mm long; surface smooth with fine concentric

lines, radial sculpture distinct at posterior end, forming reticulate scale-like sculpture. Colour variable: white, cream,

brown, grey; usually with radial bands of varying thickness and prominence; interior white to purple, often with tinted

yellow, brown or purple blotch.

Remarks. — This is the more uncommon of the two species currently known from Singapore. It was first recorded from

Singapore by Traill (1847) as an unidentified Donax species (see Discussion). This species is superficially similar to

Donax faba, but may be easily diagnosed by the presence of radial ridges and reticulate sculpture at the posterior end.

Lamprell & Whitehead (1992) provides a list of synonyms of this species.

Donax (Latona) faba Gmelin, 1791

(Figs. 1, 2, 4–6)

Donax faba Gmelin, 1791: 3264, no. 8 (type locality: none).

Donax radians Lamarck, 1818: 547, no. 6 (type locality: none).

Donax pallidus Gould, 1850: 254, 255 (type locality: Singapore) [new synonym].

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Fig. 3. Donax (Latona) cuneata Linnaeus, 1758, from Singapore: A, B, Tanah Merah Ferry Terminal (SH 21.0 × SL 26.8 mm; TSK

22809); C, D, East Coast Park (SH 21.9 × SL 29.0 mm; TSK). Scale bars = 10 mm. (Photographs by: S. K. Tan).

Fig. 4. Donax (Latona) faba Gmelin, 1791, from Singapore: A, B, Tanah Merah Ferry Terminal (SH 17.1 × SL 25.2 mm); C, D,

National Service Resort and Country Club (SH 17.3 × SL 27 mm). Scale bars = 10 mm. (Photographs by: S. K. Tan).

A

B

C

D

A, B C, D

A

B

C

D

A, B C, D

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Fig. 5. Variation in shell shape, colour and patterns in Singapore populations of Donax (Latona) faba Gmelin, 1791: A–D, Tanah

Merah Ferry Terminal (A, B, SH 17.1 × SL 25.2 mm; C, D, SH 16.4 × SL 23.5 mm; TSK 22810); E–N, National Service Resort and

Country Club (E, F, SH 17.3 × SL 27.0 mm; G. H, SH 16.3 × SL 23.7 mm; I, J, SH 15.3 × SL 24.0 mm; K, L, 16.4 × SL 25.5 mm).

Scale bars = 10 mm. (Photographs by: S. K. Tan).

Singapore records:

Donax sp. – Traill, 1847: 239 (first record); K. S. Tan & Chou, 2000: 147 [in part; topmost shell in upper figure and

lower figure]

Donax pallidus Gould, 1850: 254, 255.

Donax faba – Chuang, 1961: 206, pl. 74, fig. 2 (Siglap; Bedok). – Chuang, 1973: 197; Morris & R. D. Purchon, 1981:

325 (Changi; Bedok [see R. D. Purchon & D. E. A. Purchon, 1981: 298]); Chou et al. , 1994: 75; S K Tan & Woo,

2010: 16; Wang et al., 2011: 295.

Material examined. — Singapore: Changi (ZRC.MOL.5649), 13 Nov.2008; Changi East Bay (Red Cliff Shoal)

(ZRC.MOL.5646), Nov.2008; Tanah Merah Ferry Terminal (TSK 22810), 22 Apr.2001; National Service Resort and

Country Club (TSK 22801), Apr.1997; Marina East (ZRC.MOL.5638), 25 Jul.2009.

Distribution in Singapore. — See Fig. 2.

Habitat. — Intertidal, shallowly buried in sand of wave swept sandy beaches, migrating between the high and low tide

marks of the beach slopes following the ebb and flow of the tides (Poutiers, 1998; K. S. Tan & Chou, 2000; pers. obs.)

Diagnosis. — The following diagnosis is based on specimens from Singapore and Swennen et al. (2001). Shell thick,

compressed, inequilateral, trigonal-ovate in outline, to about 25 mm long; surface smooth with fine concentric lines that

are usually more pronounced and appear as ridges on the posterior side. Colour variable: white, cream, brown, green,

grey, purple; often with one or more radial bands and random maculations; interior white, often with tinted yellow or

with purplish blotches, to purple, usually with whitish blotches and/or radial bands.

A

B

G

H

C E

D F

I K

L J G, H I, J K, L

A, B C, D E, F

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Fig. 6. Donax (Latona) faba Gmelin, 1791 from Singapore: A–D, the syntype of Donax pallidus Gould, 1850 (USNM 17942) first

described from Singapore and now a junior subjective synonym of Donax (Latona) faba Gmelin, 1791 (see text for details); E, F, a

topotypic specimen of Donax (Latona) faba Gmelin, 1791, from the National Service Resort and Country Club (SH 14.6 × SL 21.3

mm, see Fig. 2 for location), for comparison. Scale bars = 10 mm. (Photographs by: the Smithsonian Institution [A–D], and S. K. Tan

[E, F]).

Remarks. — This is a common, sometimes locally abundant species of sandy beaches in Singapore. It was first

recorded from Singapore by Traill (1847) as an unidentified Donax species (see Discussion). The shell is somewhat

similar to Donax cuneata, but is generally more slender in shape and easily distinguished by the lack of radial sculpture

at the posterior end.

Donax pallidus Gould, 1850, has been recognised as a valid species by some authors (e.g., Drivas & Jay, 1988: 56), but

it was suggested to be possibly synoymous with Donax (Dentilatona) incarnata (Gmelin, 1791) by Huber (2010). A

comparison however, of Gould’s figure and syntype (USNM 17942) of Donax pallidus clearly shows that the taxon is a

pale form of Donax (Latona) faba Gmelin, 1791 (see Fig. 6). Donax pallidus is therefore regarded a junior subjective

synonym of Donax (Latona) faba. Incidentally, Singapore is the type locality of Donax pallidus, and Donax incarnata

has not been recorded from Singapore to date.

DISCUSSION

Two unidentified species of Donax were listed in Traill (1847) whose catalogue included shells from Singapore and its

vicinity. Although neither figures nor references were provided, we herein presume that Traill’s unidentified species are

Donax (Latona) cuneata and Donax (Latona) faba since these are the only two species with a confirmed presence in

Singapore to date.

ACKNOWLEDGEMENTS

The images of the syntype Donax pallidus Gould, 1850, are reproduced with the permission of the Smithsonian

Insitution, Washington, D.C., and we acknowledge the assistance of M. G. Harasewych in obtaining these images.

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