Brief review of the freshwater Ark shells belonging to the genus Scaphula Benson, 1834 (Fam. Arcidae).

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BRIEF REVIEW OF THE FRESHWATER ARK SHELLS BELONGING TO
THE GENUS SCAPHULA BENSON, 1834 (FAM. ARCIDAE)
Henk K. Mienis* & Oz Rittner**
Abstract: A brief enumeration is given of the species comprising the genus Scaphula Benson, 1834, a group of rarely seen
freshwater Ark shells confined in their distribution to India, Myanmar, Thailand and Vietnam.
Key-words: Mollusca, Bivalvia, Arcidae, Scaphula, freshwater, distribution.
Recent Ark shells are usually associated with marine bivalves characterized by porcelaneous shells
bearing numerous taxodont teeth on the hinge. They might belong to four families: the Arcidae, the
Parallelodontidae, the Noetiidae and the Cucullaeidae. Hardly known among students of freshwater
bivalves is the fact that among the Arcidae we can find a small group of tiny Ark shells belonging to
the genus Scaphula Benson, 1834 which live in fresh or slightly brackish water. They are confined to a
restricted area in Asia: India, Bangladesh, Myanmar, Thailand and Vietnam.
At least five species of freshwater Arks are known and they are briefly discussed below. The few
samples present in the National Mollusc Collection of the Hebrew University of Jerusalem (HUJ) are
enumerated.
Family ARCIDAE
Genus Scaphula Benson, 1834
Benson, 1834a: 91 (no type species mentioned).
Benson, 1834b: 464 (no type species mentioned).
Benson, 1836: 750 (type species by monotype: Scaphula celox Benson, 1836).
Note: Benson (1836: 750) referred to plate VII, figs. 2-3 in Gleanings of Science Vol. 1, but such a
plate was not found in the volume which I could consult, however WHB[=Benson] (1829: 265)
referred to the find of an unidentified freshwater Arca species in the Jumna River.
Scaphula celox Benson, 1836
B[enson], 1829: 265 (as Arca species).
Benson, 1834a: 91 (as Arcaceous shell).
Benson, 1834b: 465 (as Arcaceous shell).
Benson, 1836: 750.
Benson, 1856: 129.
Blanford, 1867: 72, plt. 14, figs. 14-15.
Hanley & Theobald, 1874: 47, plt. 116, figs. 8-9.
Crosse & Fischer, 1876: 339.
Fischer, 1886: 976 (as Arca (Scaphula) scaphula (sic!))
Lamy, 1907: 109 (as Arca (Scaphula) celox in part).
Preston, 1915: 129.
Annandale, 1922: 146.
Ghosh, 1922: 1139 text-figs. 1-5.
Janaki Ram & Radhakrishna, 1984: 53, table 1.
Subba Rao, 1989: 160, figs. 371-373 & 380-381.
Nesemann, Gopal & Ravindra, 2003: 6, figs. 3A-B.
Huber, 2010: 575.
Neseman, Gopal & Ravindra, 2011: 26.
Patil & Talmale, 2011: 17.

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General distribution: India and Bangladesh.
Material in HUJ: India, ex-coll. H. McClelland, ex-coll. Blok 6350 (HUJ 40855/2 valves); Orissa State,
Manahadi River, 250 miles from the coast, ex-coll. H.B. Preston, ex-coll. Coen 4891 (HUJ 40856 /1
complete specimen).
Remark: The posterior acute carina running from the umbo to the lower posterior edge consists often of
a double carina.
The figures show two Scaphula species. Left: Scaphula celox Benson, 1836, length 10.33 mm; Right: Scaphula deltae
Blanford, 1867, Length 7.51 mm. (Photographs Oz Rittner)
Scaphula pinna Benson 1856
Synonym: Scaphula bensoni H. Adams, 1872.
Benson, 1856: 128.
Adams & Adams, 1857: 540, plt. 125, figs. 6-6a.
Blanford, 1867: 72, plt. 14, figs. 11-13.
Adams, 1872: 14, plt. 3, fig. 24 (Scaphula bensoni).
Hanley & Theobald, 1874: 47, plt. 116, figs. 5-6.
Crosse & Fischer, 1876: 339.
Preston, 1915: 130.
Stevenson, 1972: 196 (Scaphula bensoni = Scaphula pinna).
Janaki Ram & Radhakrishna, 1984: 53, table 1.
Subba Rao, 1989: 160, figs. 377-379 & 382-383.
Huber, 2010: 143, textfigures, 575.
General distribution: Myanmar.
Remark: The numerous records of this species from Thailand are most probably all based on
misidentifications of Scaphula minuta (see: Additional remarks).
Material in HUJ: none.
Scaphula deltae Blanford 1867
Blanford, 1867: 71, plt. 14, figs. 7-10.
Hanley & Theobald, 1874: 47, plt. 116, figs. 2-3.

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Lamy, 1907: 109 (as Arca (Scaphula) celox in part)
Preston, 1915: 130.
Annandale, 1922: 146.
Janaki Ram & Radhakrishna, 1984: 53, Table 1.
Subba Rao, 1989: 160, figs. 374-376.
Nesemann, Gopal & Ravindra, 2003: 7, figs. 4A-B.
Huber, 2010: 143, textfigures, 575.
Neseman, Gopal & Ravindra, 2011: 26.
General distribution: India, Bangladesh and Myanmar.
Material in HUJ: Myanmar, Pegu, Irrawaddy River, leg. J.G. Dalgleish, ex-coll Blok 9793 (HUJ
40857/1 complete specimen).
Scaphula minuta Ghosh, 1922
Ghosh, 1922: 1143, text-figs. 6-7.
Brandt, 1974: 254, plt. 18, fig. 17 (as Scaphula pinna).
?Swennen et al., 2001: 67, fig. 039 (according to Huber, 2010).
Kittivorachate &Yangyuen, 2004: 134 (as Scaphula pinna).
Getwongsa, Hanjavanit, & Sangpradub, 2010: 105 (as Scaphula species).
Huber, 2010: 575.
Quang, Sinh, Tu, Lam & Lan, 2013: 24 (as Scaphula pinna)
Chompapon, Tantiwaranurak & Domrongrojwattana, 2013:128, text-fig. p. 129 (as Scaphula pinna)
Bogan & Do, 2014: 115, figs. 114-115.
General distribution: Thailand and Vietnam.
Material in HUJ: none.
Scaphula nagarjunai Janaki Ram & Radhakrishna, 1984
Janaki Ram & Radhakrishna, 1984: 51, figs. 2-3.
Subba Rao, 1989: 159 (as Scaphula nagarjuni (sic!)).
Huber, 2010: 575.
General distribution: India.
Material in HUJ: none.
Additional remarks
According to Huber (2010: 575) Brandt's large parallel sided "pinna" from northern Thailand seems to
be undescribed and represents the largest Scaphula known. Brandt (1974: 254) mentioned specimens
up to 13 mm, which is only 2 mm longer than the size given by Benson (1856: 128) for his Scaphula
pinna and only 1 mm longer than the latter's Scaphula celox (Benson, 1856: 129). Here Bogan & Do
(2014: 115) is followed and all references to Scaphula specimens from Thailand and Vietnam are
considered to belong to Scaphula minuta.
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¹ National Natural History Collections, Berman Building, Hebrew University of Jerusalem, Edmond J.
Safra Campus, IL-9190401 Jerusalem, Israel and the Steinhardt Museum of Natural History and Israel
National Center for Biodiversity Studies, Tel Aviv University, IL-6997801 Tel Aviv, Israel.
mienis@netzer.org.il
² The Steinhardt Museum of Natural History and Israel National Center for Biodiversity Studies, Tel
Aviv University, IL-6997801 Tel Aviv, Israel. israelbutterflies@gmail.com