An overview on inland freshwater molluscs
Inland freshwater molluscs in Vietnam mainly include two classes: Gastropoda and Bivalvia. Gastropoda including snail species being one of the most class of mollusc with about 30,000 descripted species and about 15,000 species in fossil forms. Fossil date of this class is continuous, started from Cambrian period. Two main groups of Caenogastropoda and Pulmonata/Hetero-branchia are main of global freshwater snail fauna. Of 409 families are recently recorded (Bouchet & Rocroi, 2005), 26 families were typical for freshwater biotopes (Neritidae, Assimineidae, Hydrobiidae, Stenothyridae), and some genera isolated from marine families and live in freshwater bodies such as Cremnoconchus (Littorinidae), Clea (Buccinidae), Rivomarginella (Marginellidae).
However, there are approximately 4,000 species of freshwater snail (or exactly 3,795-3,972 species) were descripted (Strong, Gargominy, Ponder, Bouchet, 2008). This number of snail species occupied only 70-90% of real number in nature. Of them, hydrobioids with small size (less than 5 mm) were determined about 1,000 species, occupied 25% of real number of this group, therefore, number of freshwater snail species is expected about 8,000.
Bivalvia (Pelecypoda or Lamellibranchia) including species of subclasses Pteriomorpha, Palaeoheterodonta, Heterodonta, Anomalodesmata. Global freshwater bivalve has at least 19 families in 6 orders, 4 subclasses (Deaton & Greenberg, 1991, Bogan, 2008). Up to now 1,026 species belonging to 209 genera of freshwater bivalves were recorded in global (Bogan, 2008). Families Sphaeriidae and Corbiculidae are largely radiated in freshwater. Unionoida has 6 families, about 180 genera and 800 species. Of them, families belonging to Unionoida are most diversity in species composition. Species of Unionoida are unique of bivalve have parasitically obligatory stage in gill, scale of body of host fish (Wachtler et al., 2001).
Taxonomic history of freshwater bivalve of Unionoida order started by Linnaeus (1758). Of them, several freshwater bivalve species were in a marine genus Mya. After that, taxa of freshwater bivalve that recognized by Linnaeus were moved to different genera and new taxa (Retzius, 1788; Lamarck, 1799).
The history of study on inland freshwater clams and snails in Vietnam
Compared with the group of other aquatic invertebrate, freshwater clams and snails of Vietnam, in the period before 1954, have been studied much more. The first result of freshwater clams and snails of South Vietnam and Cambodia were Crosse and Fischer announced since 1863, based on the collected specimens of Michau 1861, has recorded that 45 species of freshwater clams and snails in the Cochinchine (Nam Bo).
The author has published a list of clams and snails were found in Indochina at that time (including Thailand, Laos, Cambodia, Vietnam), including 1,129 species, belonging to 203 genera, including 323 species of fresh and brackish water clams and snails, 477 sea clams, snails and 309 species of terrestrial snails.
In 1904, the research results of the research group of Mision Pavie III on clams, snails in Indochina that are synthetized and commented by Fischer and Dautzenberg on an abundance of freshwater and brackish water snail fauna, particularity species belonging genera of Pseudodon, Canidia and families of Paludinidae, Melaniidae, Unionidae.
To the early twentieth century, there is some researchers adding new species or described new species for science such as Rolle (1904), Dautzenberg & Fischer (1905, 1908), Demage (1912), Haas (1910, 1924-1925, 1929), Prashad (1928) etc., but can say that the works of Fischer and Dautzenberg fairly complete basic species composition of freshwater clams and snails in Indochina and Vietnam in particular. However, it should be noted that in study results before 1954 on composition of freshwater clams and snails in the Vietnam, that are many issues unclear on taxonomical position, nomenclature of many species. There are many new species for sciense described are unfounded in the works of Fischer & Dautzenberg.
From 1954 to now, there are many studies on freshwater mollusks of both two regions of northern and southern Vietnam. Of them, in publication of Dang Ngoc Thanh et al. (1980): Identification offreshwater invertebrates of North Vietnam, 99 species including 47 species of snail, 52 species of clams are recorded and described in detail. This work can be the uniquely sufficient publication on freshwater mollusks in North Vietnam in that time.
Beginning in the early years of the twenty-first century, the work of investigation, research mussels, freshwater snails Vietnam got another start for a new phase to complete monograph of this group. Dang Ngoc Thanh, Ho Thanh Hai (2002) recognized 141 species of inland freshwater clams and snails belonging to 59 genera, 21 families. Of them, the number of species firstly described in Vietnam occupied one third of total number of species found in this area. These species are characterized for Vietnam or Indo-China area. This shows high specificity of the fauna of freshwater clams, snails in Vietnam.
In the group of snails, the species with less than 5 mm in size were little known previously becaused they often escaped from sampling tools. Therefore, until 2002, in Vietnam, the taxa of small snails belong Pomatiopsidae not been studied, or some other families such as Stenothiridae, Assimineidae etc. has not been sufficiently studied before.
Recently, the collection of freshwater snails is continuously supplemented by samling in investigations implemented in whole Vietnam, particularly snails with small size less than 5 mm were noted sampling and research on taxonomy. Based on analysis of snails collected from inland freshwaters of Vietnam, Dang Ngoc Thanh, Ho Thanh Hai (2003, 2004, 2006, 2007, 2008) revised on species composition of several families of freshwater snails such as Ampullariidae, Viviparidae, Thiaridae, Stenothiridae and subfamily Triculinae belonging to family Pachychilidae (the family with small size of body less than 5 mm).
Recently, besides the Vietnamese experts, also foreign scientists conducted the investigation on taxonomy some taxa of freshwater snails in Vietnam. In the new studies on taxonomy revision of freshwater snails in Southeast Asia, and in the whole of Vietnam, such as works of Köhler (2002, 2006, 2009), Köhler & Glaubrecht (2006) on family of Pachychilidae building towards morphological taxonomy, combined with anatomy, embryonic development, and techniques of modem molecular biology.
Investigations, studies on systematic, taxonomy of freshwater mollusks in global, ASEAN and in Vietnam as well have experienced many stages with some good results. However, in all most of studies on taxonomy of freshwater mollusks of Vietnam mainly based on morphological criteria of shell, meanwhile in many countries, advanced technique aided for taxonomy such as comparison anatomy of reproductive organs, morphology of young and DNA sequence of mitochondria. That limited exactness of taxonomy when determination of species that have exchanges on morphology by different habitats. Moreover, there are many different views and judgment on systematic, phylogeny, evolution of freshwater mollusks in general, taxa of lower levels particularly. Therefore, these existences should be continuously studied and discussed much again in future.
Species composition of inland freshwater clams and snails in Vietnam
On the basis of analysis of samples collected continuously added over the years, so far has identified a check list of 168 species of freshwater clams and snails known in Vietnam belonging to 71 genera, 25 families, including 93 species of snails (41 genera, 17 families) and 75 species of clams, mussels (30 genera, 8 families).
The number of clams and snails such freshwater (excluding the clams, snails described above new fossil specimens of about 55-25 million years ago) may be insufficient compared to the actual nature of the current Vietnam today by many species, especially small sized snails belonging to family Pomatioptsidae that have not obtained samples. And some specimens collected, so far, are not enough documentation to determine the name.
The subfamily Triculinae with small sized snails in the middle and lower Mekong (southern Laos, Thailand and Cambodia) has 92 species (Davis, 1979), while in Vietnam, identified 15 new species, including 13 species new to science and was first described. This shows that in nature, the number of species of snail subfamily Triculinae in Vietnam still have more. Brandt (1974) gave 380 species and subspecies of freshwater, brackishwater clams and snails in Thailand, of which 284 species and sub - species of snail and 96 species and subspecies of clams, mussels. From the resulting data, one could estimate the quantities of inland freshwater clams and snails in Vietnam if fully well right more than 200 species.
A CHECKLIST OF INLAND FRESHWATER CLAMS AND SNAILS
SPECIES IN VIETNAM
(All the species are listed in accordance to numbers indicated in the content)
PHYLUM MOLLUSCA
CLASS GASTROPODA
SUBCLASS PROSOBRANCHIA
SUPERORDER CAENOGASTROPODA
ORDER MESOGASTROPODA
1. Family Viviparidae Gray, 1847
- Angulyagra boettgeri (Heude, 1890)
- Angulyagra duchieri (Fischer, 1898)
- Angulyagra polyzonata (Frauenfeld, 1862)
- Sinotaia aeruginosa (Reeve, 1863)
- Cipangopaludina lecythoides (Benson, 1856)
- Filopaludina sumatrensis (Dunker, 1852)
- Idiopoma umbilicata (Lee, 1856)
- Mekongia lithophaga (Heude, 1889)
- Mekongia hainesiana (Lea, 1864)
2. Family Ampullariidae Gray, 1847
10. Pilapolita (Deshayes, 1830)
11. Pila conica (Wood, 1828)
12. Pila ampullacea (Linnaeus, 1758)
13. Pomacea canaliculata (Lamarck, 1819)
14. Pomacea maculata Perry, 1810
3. Family Bithyniidae Walker, 1927
15. Allocinma longicornis (Benson, 1836)
16. Bithyniafuchsiana (Möellendorff, 1888)
17. Bithynia goniomphalos (Morelet, 1866)
18. Bithynia misella (Gredler, 1884)
19. Digoniostoma siamensis (Lea, 1856)
20. Parafossarulus striatulus (Benson, 1856)
21. Wattebledia crosseana (Wattebled, 1886)
ORDER SORBEOCONCHA
4. Family Pachychilidae Troschel, 1857
22. Adamietta housei (Lea, 1856)
23. Adamietta reevei (Brot, 1862)
24. Brotia annamita Köhler, Holford, Do & Ho, 2009
25. Brotia costula (Rafmesque, 1833)
26. Brotia dautzenbergiana (Morlet, 1884)
27. Brotia hoabinhensis Köhler, Holford, Do & Ho, 2009
28. Brotia swinhoei (Adams, 1870)
29. Sulcospira collyra Köhler, Holford, Do & Ho, 2009
30. Sulcospira dakrongensis Köhler, Holford, Do & Ho, 2009
31. Sulcospira hainanensis (Brot, 1872)
32. Sulcospira proteus (Dautzenberg & Fischer, 1906)
33. Sulcospira quangtriensis Köhler, Holford, Do & Ho, 2009
34. Sulcospira tonkiniana (Morlet, 1887)
35. Sulcospira touranensis (Souleyet, 1852)
36. Sulcospira vietnamensis Köhler, Holford, Do & Ho, 2009
37. Semisulcospira aubryana (Heude, 1888)
38. Paracrostomapaludiformis (Yen, 1939)
5. Family Thiaridae Gray, 1847
39. Melanoides tuberculatus (O. F. Müller, 1774)
40. Neoradina prasongi Brandt, 1974
41. Sermyla tornatella (Lea, 1851)
42. Tarebia granifera (Lamarck, 1822)
43. Thiara scabra (O. F. Müller, 1774)
ORDER HYPSOGASTROPODA
6. Family Littorinidae Gray, 1847
44. Cremnoconchus messageri Bav. & Dautz., 1900
7. Family Assimineidae H. Adams & A. Adams, 1858
45. Assiminea brevicula (Pfeiffer, 1854)
46. Assiminea francoisi Dautz. & Fisch., 1905
47. Assiminea lutea Adams A., 1861
48. Assiminea obtusa Wattebled, 1886
49. Assiminea interrupta Dautz. & Fisch., 1905
8. Family Fairbankiidae Thiele, 1928
50. Fairbankia cochinchinensis Bav. & Dautz., 1910
51. Fairbankia rohdei Brandt, 1968
52. Fluviocingula elongata Dang, 1967
9. Family Stenothyridae P. Fischer, 1887
53. Stenothyra alba Dang & Ho, 2010
54. Stenothyra conica Dang & Ho, 2010
55. Stenothyra cyrtochila van Benthem, 1959
56. Stenothyra divalis (Gould, 1859)
57. Stenothyra glabra A. Adams, 1861
58. Stenothyra glabrata (A. Adams, 1851)
59. Stenothyra messageri Bav. & Dautz., 1900
60. Stenothyra monilifera (Benson, 1856)
61. Stenothyra ovata Dang & Ho, 2010
62. Stenothyra polita (A. Adams, 1851)
63. Stenothyra schlickumi Brandt, 1968
10. Family Iravadiidae Thiele, 1928
64. Iravadia ornata Blanford, 1867
65. Iravadia reticulata Brandt, 1968
66. Iravadia tuberculata Brandt, 1974
11. Family Pomatiopsidae Stimpson, 1865
Subfamily Triculinae Annandale, 1924
67. Tricula ovata Dang & Ho, 2006
68. Tricula semilunaris Dang & Ho, 2006
69. Vietricula alba (Dang & Ho, 2006)
70. Vietricula caobangensis Dang & Ho, 2011
71. Vietricula flexuosa (Dang & Ho, 2006)
72. Vietricula laki Dang & Ho, 2010
73. Vietricula leae (Dang & Ho, 2006)
74. Vietricula minuta (Dang & Ho, 2006)
75. Vietriculapioacensis Dang & Ho, 2011
76. Vietricula serepoki Dang & Ho, 2010
77. Vietricula sinhoensis (Dang & Ho, 2006)
78. Vietricula taybacensis (Dang & Ho, 2006)
79. Vietricula undulata (Dang & Ho, 2006)
Subfamily Lithoglyphinae P. Fischer, 1885
80. Lacunopsis harmandi Poirier, 1881
81. Paraprososthenia levayi (Bavay, 1895)
12. Family Fluminicolidae Clessin, 1880
82. Lithoglyphopsis tonkinianus Bav. & Dautz., 1900
ORDER NEOGASTROPODA
13. Family Buccinidae Fleming, 1821
83. Clea (Anentome) Helena (Philipi, 1847)
SUBCLASS PULMONATA ORDER BASOMMATOPHORA
14. Family Ancylidae Rafinesque, 1815
84. Pettancylus brenieri (Bav. & Dautz., 1912)
15. Family Lymnaeidae Gray, 1842
85. Lymnaea rubiginosa (Michelin, 1831)
86. Lymnaea swinhoei H. Adams, 1866
87. Lymnaea viridis Quoy & Gaimard, 1832
87* Lymnaea sp.
16. Family Bulinidae Baker, 1945
88. Indoplanorbis exustus (Deshayes, 1834)
17. Family Planorbidae Gray, 1840
89. Gyraulus heudei (Clessin, 1886)
90. Gyraulus convexiusculus (Hutton, 1849)
91. Hippeutis umbilicalis (Benson, 1836)
92. Polypylis hemisphaerula (Benson, 1842)
CLASS BIVALVIA SUBCLASS PTERIOMORPHA
ORDER ARCOIDA
18. Family Arcidae Lamarck, 1809
93. Scaphula minuta Gosh, 1922
ORDER MYTILOIDA
19. Family Mytilidae Rafinesque, 1815
94. Limnopema fortunei (Dunker, 1857)
SUBCLASS PALAEOHETERODONTA ORDER UNIONOIDA
20. Family Unionidae Fleming, 1828
95. Chamberlainia hainesiana (Lea, 1856)
96. Contradens crossei (Deshayes, 1876)
97. Contradens fultoni (Haas, 1930)
98. Contradens tumidula (Lea, 1856)
99. Cristaria bialata (Lea, 1829)
100. Cristaria herculea (Middendorff, 1848)
101. Cristaria plicata (Leach, 1814)
102. Cristaria truncata Dang, 1980
103. Cuneopsis demangei Haas, 1929
104. Ensidens ingallsianus (Lea, 1852)
105. Hyriopsis bialatus Simpson, 1900
106. Hyriopsis delaportei (Crosse & Fischer, 1876)
107. Lanceolaria bilirata (von Martens, 1902)
108. Lanceolaria fruhstorferi (Bav. & Dautz., 1901 )
109. Lanceolaria gladiola (Heude, 1877)
110. Lanceolaria grayii (Gray in Grif. & Pidg., 1833)
111. Lanceolaria laevis (von Martens, 1902)
112. Nodularia douglasiae (Griffith & Pidgeon, 1833)
113. Nodularia dorri (Wattebled, 1886)
114. Oxynaia diespiter (Mabille, 1887)
115. Oxynaia jourdyi (Morlet, 1886)
116. Oxynaia micheloti (Morlet, 1886)
117. Physunio micropterus (Morelet, 1866)
118. Physunio superbus (Lea, 1843)
119. Pilsbryoconcha compressa (Martens, 1860)
120. Pilsbryoconcha exilis (Lea, 1838)
121. Pilsbryoconcha lemeslei (Morelet, 1875)
122. Pletholophus discoideus (Lea, 1834)
123. Pletholophus inangulatus (Haas, 1910)
124. Pletholophus swinhoei (Adams, 1866)
125. Protunio messageri (Bavay & Dautzenberg, 1901)
126. Pseudodon inoscularis (Gould, 1844)
127. Pseudodon mouhotii (Lea, 1863)
128. Pseudodon resupinatus Martens, 1902
129. Pseudodon thompsoni Morlet, 1884
130. Ptychorhynchuspfisteri (Heude, 1874)
131. Sinanodonta elliptica (Heude, 1878)
132. Sinanodonta jourdyi (Morlet, 1886)
133. Sinohyriopsis cumingii (Lea, 1852)
134. Solenaia iridinae (Heude, 1874)
135. Trapezoideus comptus (Deshayes & Jullien, 1874)
136. Trapezoideus exolescens (Gould, 1843)
137. Unionetta fabagina (Deshayes & Jullien, 1874)
21. Family Amblemidae Rafinesque, 1820
138. Diaurora aurorea (Heude, 1883)
139. Gibbosula crassa (Wood, 1815)
140. Lamprotula bazini (Heude, 1877)
141. Lamprotula blaisei (Dautz. & Fischer, 1905)
142. Lamprotula caveata (Heude, 1877)
143. Lamprotula leai (Gray in Griffith & Pidgeon, 1833)
144. Lamprotula liedtkei (Rolle, 1904)
145. Lamprotula nodulosa (Wood, 1815)
146. Scabies crispata (Gould, 1843)
22. Family Margaritiferidae Henderson, 1929
147. Margaritanopsis laoensis (Lea, 1863)
SUBCLASS HETERODONTA
ORDER VENEROIDA
23. Family Sphaeriidae Deshayes, 1855
148. Pisidium clarkeanum Nevill & Nevill, 1871
24. Family Dreissenidae Gray, 1840
149. Sinomytilus harmandi (Rochebrune, 1881)
25. Family Cyrenidae (= Corbiculidae) Gray, 1847
150. Geloina bengalensis (Lamarck, 1818)
151. Geloina coaxans (Gmelin, 1791)
152. Geloina expansa (Mousson, 1849)
153. Corbicula baudoni Morlet, 1886
154. Corbicula blandiana Prime, 1864
155. Corbicula bocourti Morelet, 1865
156. Corbicula Castanea (Morelet, 1865)
157. Corbicula cyreniformis Prime, 1860
158. Corbicula fluminea (O. F. Müller, 1774)
159. Corbicula lamarckiana Prime, 1867
160. Corbicula leviuscula Prime, 1864
161. Corbicula luteola Prashad, 1929
162. Corbicula lydigiana Prime, 1861
163. Corbicula messageri Bav. & Dautz., 1901
164. Corbicula moreletiana Prime, 1867
165. Corbicula siamensis Prashad, 1928
166. Corbicula solidula Prime, 1861
167. Corbicula tenuis Clessin, 1887
Note: (*): This species with data unavailable is not included in the content.
Characteristics on the North-Southern distribution of freshwater snails, clams in Vietnam
The nature of the North-Southern distribution of inland freshwater clams and snails has been clearly expressed: each of the North and the South of Vietnam has different characterized species groups. Typical species for the North Vietnam belonging to genera of Cuneopsis, Protunio, Chamberlainia, Hyriopsis, Solenaia etc. that are endermic species for Vietnam, or may be distributed in the South China. Especially, whole 6 species belonging to genus Lamprotula (family Amblemidae) distributed only in the Red River system and Bang River belonging to Bac Bo area.
Of total 46 endermic species of clams and snails for Vietnam, there are 31 endermic species for North Vietnam (occupied 67.4% of total endermic species of clams and snails for Vietnam). There are some species only distributed in the South Vietnam but not found in North such as Wattebledia crosseana, Indoplanorbis exustus, Mekongia hainesiana, Ensidens ingallsiana, Hyriopsis bialatus, Hyriopsis delaportei, Physunio superbus, P. micropterus, Pilsbryoconcha exilis, Unionetta fabagina, Pseudodon exilis, P. lemeslei, Sinomytilus harmandi, Vietricula serepoki, V. laki, Lacunopsis harmandi, Scaphula minuta, etc.
Characteristics on zoogeography of inland freshwater clams, snails in Vietnam
Vietnam's territory stretches over 14 latitudes with a large range of climate change. Particularly important is that there are two major river systems in the North of the Red river and the Mekong river in Southern Vietnam is a basis for differentiating characteristics of freshwater snails and clams between these two regions. In terms of zoogeography, can distinguish the following species composition of freshwater clams and snails in Vietnam as follows:
- The species is widely distributed in Central India and the world: including 21 species.
- The tropical species, distributed in the sub-region of India-Malaixia and to the North Vietnam: 52 species.
- The common species with China. This component consists of 49 species.
- The species endemic to Vietnam. This component accounts for the largest, to 46 species, demonstrating high levels of endemism of mussels, freshwater snails Vietnam.
|
Rate % the species is widely distributed
|
Rate % the tropical species native Indian - Malaixia
|
Rate % the species native China
|
Rate % the endermic species
|
|
21 (12.5%)
|
52 (30.9%)
|
49 (29.2%)
|
46 (27.4%)
|
The position of Vietnam in the bio-geographical zoning Oriental region (Region Central India)
Opinion of the majority of authors studies on bio-geographical present that can not be considered as a whole Vietnam homogeneous unit on bio-geography in the biogeographical Oriental region (Central-India) due to the significant differences between North and South Vietnam, both in terms of structure, bio-geographical relationships, both in features and hydrological systems, climate regime.
So more reasonable to consider South Vietnam (south boundary Deo Ngang-Hai Van Pass, 16°-18° north latitude) as a unit under the sub-region of India-Malaixia, with tropical species composition absolutely dominant, with a tropical climate regime typical Mekong system separate from the Red River system in Northern Vietnam.
North Vietnam (north boundary of Hai Van Pass) have considered a particular biogeographical unit, separate from the sub-region of India-Malaixia (including South Vietnam) in the south as well as the sub-region of China in the North. Independent nature of North Vietnam with neighboring bio-geographical units based on the following:
1) North Vietnam can be considered as lying in the boundary area between the aggregate distribution subtropical species north and gather south tropical species, meaning transition zone on zoo-geography.
2) North Vietnam has a high component of endemic species (31 species of clams and snails, 26 species of freshwater shrimps, crabs) both endemism degree and endemism level. The degree of endemism of freshwater fauna of North Vietnam showing characteristics of this area compared with neighboring areas, but that there are very large natural obstacles, make it difficult to consider this region as a province of China’s sub-region as well as the sub-region of India-Malaixia.
If we consider only groups of species distributed in North Vietnam and South China are endemic to the area of North Vietnam and South China, the degree of endemism for bigger areas (particularly freshwater fish to 136/193 species, 37 genera, other animal groups to 101/346 species). This level of endemism can we consider this area (South China-North Vietnam) as a distinctive sub-region, separate from the existing sub-regions in Central India’s region.
3) In terms of natural conditions in general, we can see the separation of the Red River system, Da River, Ma River, both in North Vietnam to the Mekong river system in Southern Indochina Peninsula. To the North of Vietnam, we can see the relationship between the system near the Red River and Pearl river (Xijiang), the upper part of the Pearl river is located in the territory of North Vietnam (Ky Cung river in Lang Son province, Bang River in Cao Bang province), separate from the system much more distant Yangtze to the North. Panoramic hydrological system in Eastern Asia region, could see intermediate position of the Red river system-the Pearl river, between two large river systems North and South basins created three separate areas together, with different properties in East Asia:
a. Yangtze river flows Northeast to the system of reservoirs downstream.
b. Pearl river and Red river flows East, South east with a small lake in the area of the South and North Vietnam. This area is separated from the Yangtze basin area by the mountain, that was Mori considered as natural boundary separating the two sets of different species. It can be considered as high limit absolute distribution north of the tropical species and the absolute lower limit distribution south of the species temperate and subtropical in Eastern Asia.
c. Catchments of Mekong river flow South with system of lakes, rivers in Tay Nguyen highlands (South Vietnam) and the Tonle Sap (Cambodia), separated from the area over by Truong Son range, that is considered as the natural boundary, split two sets different species: India - Malaixian species to the South and assemble mixed species also has elements of temperate, subtropical of North Vietnam and South China.
4) Separation of northern Vietnam as a zoo-geographical unit, independent of the sub-region of China and the sub-region of India-Malaixia is also consistent with the climate regime typical of this region.
Expanding on this point, considering the close nature of the aquatic species composition of the South China and North Vietnam as well as a close relationship between the hydrological system of the two regions, as discussed above may propose the establishment of the sub-region of the North Vietnam-South China in the Oriental region, the nature of transition between two the sub-regions of China and the subregion of India-Malaixia in East Asia (Dang Ngoc Thanh, Ho Thanh Hai, Duong Due Tien, Mai Dinh Yen, 2002).
KEYS TO GENERA AND SPECIES OF INLAND FRESHWATER SNAILS AND
CLAMS IN VIETNAM
Family VIVIPARIDAE GRAY, 1847
Key to genera in Vietnam
| 1a |
Shell large, over 40 mm, broad |
Cipangopaludina |
| b |
Shell medium or small in size, less than 40 cm, narrowly-elongated |
2 |
| 2a |
Shell thick, with spual edges, without umbilicus |
Angulyagra |
| b |
Shell thin or moderately thick, with or without umbilicus |
3 |
| 3a |
Umbilicus large, deep, shell small, less than 20 cm |
Idiopoma |
| b |
Umbilicus very narrow, length over 20 cm |
4 |
| 4a |
Shell moderately thick with spiral black thin lines |
Filopaludina |
| b |
Shell ovate or elongated, umbilicus clear |
5 |
| 5a |
Shell shortly-ovate, with axial edges on body whorl, whorl convex |
Mekongia |
| b |
Shell long, with spiral brown lines on body whorl |
Sinotaia |
Genus Angulyagra Rao, 1931
Key to species in Vietnam
| 1a |
Shell very thick. Length of aperture higher than spire |
Angulyagra duchieri |
| b |
Shell moderately thick. Length of aperture equal or lower than spire |
2 |
| 2a |
Shell elongated pyramid, length equal or more than 30 mm. Whorls flatted, aperture heart shaped |
Angulyagra boettgeri |
| b |
Shell shortly conic, length lower than 30 mm. Whorls inflated, aperture rather circle |
Angulyagra polyzonata |
Genus Mekongia Crosse & Fischer, 1876
Key to species in Vietnam
| 1a |
Suture deep. Umbilicus clear. Inside angle of aperture's anterior margin acute |
Mekongia hainesiana |
| b |
Sutter low. Umbilicus unclear. Inside angle of aperture's anterior margin round |
Mekongia lithophaga |
Family AMPULLARIIDAE GRAY, 1847
Key to genera in Vietnam
| 1a |
Shell with umbilicus large and deep |
Pomacea |
| b |
Shell without umbilicus or umbilicus thin, short |
Pila |
Genus Pomacea Perry, 1810
Key to genera in Vietnam
| 1a |
Shell elongated, spire high, suture deep, angle at base of aperture acute |
Pomacea canaliculata |
| b |
Shell circle, spire low, suture shallow, angle at base of aperture right |
Pomacea maculata |
Genus Pila Roding, 1798
Key to species in Vietnam
| 1a |
Shell large, conic, surface with deep brown ribs |
Pila ampullacea |
| b |
Shell large or medium, ovate or circle, surface with or without spiral ribs |
2 |
| 2a |
Shell large, ovate, surface shiny without deep brown ribs, spire high, aperture narrow |
Pila polita |
| b |
Shell medium, surface not shiny, with or without deep brown ribs, spire low, aperture large |
Pila conica |
Family BITHYNIIDAE WALKER, 1927
Key to genera in Vietnam
| 1a |
Umbilicus deep, cleared |
Digoniostoma |
| b |
Without umbilicus or unclear |
2 |
| 2a |
Shell shortly-ovate, thick |
Allocinma |
| b |
Shell elongated, thin |
3 |
| 3a |
Shell smooth, body whorl convex in medium |
4 |
| b |
Shell with sprial ribs, body whorl regularly round |
Parafossarulus |
| 4a |
Peristome tortuous generally quadrilateral |
Wattebledia |
| b |
Peristome round, without tortuous |
Bithynia |
Genus Bithynia Leach, 1818
Key to species in Vietnam
| 1a |
First whorls occupied only 1/4 length of shell. The body whorl not convex. Aperture formed the upper angle |
Bithynia fuchsiana |
| b |
First whorls occupied 1/2 length of shell. The body whorl is not convex. Aperture not formed the upper angle |
2 |
| 2a |
Apex obtuse |
Bithynia misella |
| b |
Apex slightly pointed often eroded |
Bithynia goniomphalos |
Family PACHYCHILIDAE TROSCHEL, 1857
Key to genera in Vietnam
| 1a |
Shell pyramid elongated, pointed with 9-10 whorls |
2 |
| b |
Shell shortly conic, less than 10 whorls |
3 |
| 2a |
Shell medium or small size. Whorls flatted, aperture shortly, aperture rhomboidal. Shell smooth without spiral ribs |
Adamietta |
| b |
Whorls convex, aperture oval. Shell sculptured, with spiral ribs, raw axial edges |
Brotia |
| 3a |
Shell elongated but width narrow, smooth |
Sulcospira |
| b |
Shell short but width large, apex eroded |
4 |
| 4a |
Shell smooth, body whorl large and convex |
Paracrostoma |
| b |
Shell sculptured, with axial edges. Body whorl not convex |
Semisulcospira |
Genus Adamietta Brandt, 1974
Key to species in Vietnam
| 1a |
Surface of shell without axial black brown ribs. Aperture short |
Adamietta reevei |
| b |
Surface of shell with axial black brown ribs. Aperture normal |
Adamietta housei |
Genus Brotia Adams, 1866
Key to species in Vietnam
| 1a |
Shell with harsh spiral and axial edges |
2 |
| b |
Shell without harsh spiral, axial edges |
3 |
| 2a |
Shell long, pyramid. The body whorl shorter than remained whorls |
Brotia swinhoei |
| b |
Shell short, large, conic. The body whorl longer than remainders |
Brotia annamita |
| 3a |
Shell medium, elongated tube-shaped, with axial deep brown lines |
Brotia dautzenbergiana |
| b |
Shell large, pyramid, without axial deep brown lines |
4 |
| 4a |
With 7-9 whorls, aperture rhombus, slightly wider, high 1/3 height of shell |
Brotia hoabinhensis |
| b |
With 9 whorls, aperture ellipse, shorter then less 1/3 height of shell |
Brotia costula |
Genus Sulcospira Troschel, 1857
Key to species in Vietnam
| 1a |
Shell thick, apex often pointed, outer peristome very thick |
Sulcospira proteus |
| b |
Shell thin, apex often eroded, outer peristome normal |
2 |
| 2a |
Shell with distinctly axial edges |
Sulcospira tonkiniana |
| b |
Shell smooth, without axial edges |
3 |
| 3a |
Shell piramid, apex pointed |
Sulcospira collyra |
| b |
Shell elongated, apex often eroded |
4 |
| 4a |
With 6-7 whorls |
Sulcospira touranensis |
| b |
Shell shortly-conic |
5 |
| 5a |
With 5-6 whorls, moderately flat |
Sulcospira hainanensis |
| b |
Shell large, thick-conic |
6 |
| 6a |
Shell conic, thick, with 6-8 whorls |
Sulcospira vietnamensis |
| b |
Shell conic, thin, with 4-6 whorls |
7 |
| 7a |
Shell with 4-5 whorls, aperture oval |
Sulcospira dakrongensis |
| b |
Shell with 5-6 whorls, aperture lozenge |
Sulcospira quangtriensis |
FAMILY THIARIDAE GRAY, 1847
Key to genera in Vietnam
| 1a |
Shell with 6,7 whorls |
2 |
| b |
Shell with more than 8 whorls |
3 |
| 2a |
Apex obtuse, sutures shallow, with deep spiral grooves and axial edges |
Sermyla |
| b |
Apex pointed, sutures deep, with row tubercles or thin spines |
Thiara |
| 3a |
Shell with tubercles rows or axial ridges |
4 |
| b |
Shell smooth, with dimly spiral lines. Shell large for the genus, elongated, apex pointed or eroded, whorls flatted
|
Neoradina |
| 4a |
Shell conic, the length of body whorl more than 1/2 of the shell height, with spiral tubercles |
Tarebia |
| b |
Shell pyramid, elongated, the length of body whorl less than 1/2 of the shell height, with spiral lines and axial ridges |
Melanoides |
FAMILY ASSIMINEIDAE H. & A. ADAMS, 1858
Genus Assiminea Fleming, 1828
Key to genera in Vietnam
| 1a |
Shell less than 5 mm. Whorls inflated |
2 |
| b |
Shell more 5 mm. Whorls flatted |
3 |
| 2a |
Shell ovate |
Assiminea francoisi |
| b |
Shell moderately circle |
Assiminea obtusa |
| 3a |
The body whorl forms an angle below, therefore shell pointed pyramid with light yellow color |
Assiminea interrupta |
| b |
The body whorl gradually round, shell ovate, red or yellow color |
4 |
| 4a |
Whorls flatted, sutures shallow |
Assiminea brevicula |
| b |
Whorls moderately inflated, sutures distinct |
Assiminea lutea |
FAMILY FAIRBANKIIDAE THIELE, 1928
Genus Fairbankia Blanford, 1868
Key to species in Vietnam
| 1a |
Shell conic, prolonged, with 8-10 whorls, apex pointed |
Fairbankia cochinchinensis |
| b |
Shell shortly conic, with 4-5 whorls, apex obtuse |
Fairbankia rohdei |
FAMILY STENOTHYRIDAE p. FISCHER, 1887
Genus Stenothyra Benson, 1856
Key to species in Vietnam
| 1a |
Shell surface with dotted lines |
2 |
| b |
Shell surface smooth |
5 |
| 2a |
Shell height less than 5 mm |
3 |
| b |
Shell height more than 5 mm |
4 |
| 3a |
Elliptical aperture, large ombilicus. Body whorl slightly bulging towards the left en |
Stenothyra messageri |
| b |
Round aperture, narrow umbilicus. Body whorl oblongish, not bulging. Whorls with dotted lines |
Stenothyra monilifera |
| 4a |
Shell almost triangular, with 5 whorls, apex pointed |
Stenothyra polita |
| b |
Shell egg-shaped, with 3-4 whorls |
Stenothyra ovata |
| 5a |
The height of shell more than 3 mm. Egg-shell, oblongish, with oblique thin lines |
6 |
| b |
The height of shell less than 3 mm |
7 |
| 6a |
Apex obtuse, with 4 whorls. Aperture ellipe |
Stenothyra diavalis |
| b |
Apex pointed, with 4,5 whorls. Aperture slightly oblique |
Stenothyra glabrata |
| 7a |
Shell almost transparent, yellow-brown color |
Stenothyra glabra |
| b |
Shell small, the height only 2 mm |
8 |
| 8a |
Bright yellow shell, with only sparse lines, fuzzy. Spire short, equal 1/5 height of shell |
Stenothyra schlickumi |
| b |
Shell solid, triangular |
9 |
| 9a |
Shell milky-white color. Aperture almost ellipe, slightly circle, shallow |
Stenothyra alba |
| b |
Shell ovate or conic, thin |
10 |
| 10a |
Shell ovoid, copper color |
Stenothyra cyrtochila |
| b |
Shell conic, yellow-brown color |
Stenothyra conica |
FAMILY IRAVADIIDAE THIELE, 1928
Genus Iravadia Blanford, 1867
Key to species in Vietnam
| 1a |
Shell oval, aperture large semicircular |
Iravadia ornata |
| b |
Shell conic, aperture round |
2 |
| 2a |
Shell with spiral ridges, colored by yellow-brown bands |
Iravadia reticulata |
| b |
Shell with spiral rows of tubercles, violet bands |
Iravadia tuberculata |
FAMILY POMATIOPSIDAE STIMPSON, 1865
SUBFAMILY TRICULINAE ANNANDALE, 1924
Key to genera in Vietnam
| 1a |
Shell elongated, 7-8 whorls, the body whorl with height less than 1/2 spire |
Tricula |
| b |
Shell pyramid or conic, less than 7 whorls, the body whorl with height equal or more than 1/2 spire |
Vietricula |
Genus Tricula Benson, 1843
Key to species in Vietnam
| 1a |
Shell thin, 8 whorls, shiny white color. The body whorl equal 1/4 of spire. Aperturesemi lunar or moderately circular |
Tricula semilunaris |
| b |
Shell thin, 7 whorls, yellow color with brown-spots. The body whorl equal 1/3 of spire. Aperture oval |
Tricula ovata |
Genus Vietricula Dang & Ho, 2006
Key to species in Vietnam
| 1a |
Lip thick, tortuous |
2 |
| b |
Lip not tortuous |
3 |
| 2a |
Aperture single, lip moderately protruded up in middle part |
Vietricula undulata |
| b |
Aperture double, lip moderately protruded up in above, below and middle parts |
Vietricula flexuosa |
| 3a |
Shell pyramid |
4 |
| b |
Shell conic |
7 |
| 4a |
Peristome single |
5 |
| b |
Peristome double |
6 |
| 5a |
Aperture drop of water-shaped, length of shell less than 4 mm |
Vietricula taybacensis |
| b |
Aperture forms an acute angle above, length of shell more than 4 mm |
Vietricula serepoki |
| 6a |
Aperture semi lunar, above angle far from body whorl |
Vietricula sinhoensis |
| b |
Aperture oval, above angle near body whorl |
Vietricula leae |
| 7a |
Suture double, aperture subsemiluna. Shell thin |
Vietricula alba |
| b |
Suture single |
8 |
| 8a |
Aperture drop of water-shaped. The length more than 3 mm |
Vietricula laki |
| b |
Shell less than 3 mm |
9 |
| 9a |
Aperture oval. Lip thick. The length less than 3 mm |
Vietricula minuta |
| b |
Aperture semilunar or narrow lozenge |
10 |
| 10a |
Aperture semiluna. Spire less than 1/2 the height of shell |
Vietricula pioacensis |
| b |
Aperture narrow lozenge. Spire equal only 1/3 the height of shell |
Vietricula caobangensis |
SUBFAMILY LITHOGLYPHINAE P. FISCHER, 1885
Key to genera in Vietnam
| 1a |
Shell smooth, the body whorl is flatted and moderately concave |
Lacunopsis |
| b |
Shell conic, with spfral edges |
Paraprososthenia |
FAMILY LYMNAEIDAE GRAY, 1842
Lymnaea Lamarck, 1799
Key to species in Vietnam
| 1a |
Umbilicus narrow |
2 |
| b |
Without umbilicus |
Lymnaea rubinosa |
| 2a |
Shell large in width, the height more than 20 mm. Aperture largely ear-shaped. The rate lo/Lo = 0.75-0.88. The angle of basal aperture nearly square |
Lymnaea swinhoei |
| b |
Shell narrow in width, the height smaller 20 mm. Aperture oval. The rate lo/Lo = 0.6-0.7. The angle of basal aperture obtuse |
Lymnaea viridis |
FAMILY PLANORBIDAE GRAY, 1840
Key to genera in Vietnam
| 1a |
Shell semicircular, the body whorl with 3 or more spiral ridges inside |
Polypylis |
| b |
Shell plate-shaped, the body without spiral ridges |
2 |
| 2a |
The body whorl without angle in middle line. Umbilicus shallow |
Gyraulus |
| b |
The body whorl with angle below. Umbilicus large and deep |
Hippeutis |
Genus Gyraulus Charpentier, 1837
Key to species in Vietnam
| 1a |
The body whorl with thin hem in lateral margin |
Gyraulus heudei |
| b |
The body whorl without thin hem, with or without round angle |
Gyraulus convexiusculus |
FAMILY UNIONIDAE FLEMING, 1828
Key to genera in Vietnam
| 1a |
Shell without teeth, thin, wing not developed |
Sinanodonta |
| b |
Shell with teeth, wing developed or not |
2 |
| 2a |
Shell with lactero-posterial teeth elongated edge-shaped. Wing very developed, shell often thin, smooth |
3 |
| b |
Shell with 2 lactero-posterial teeth long plate-shaped |
5 |
| 3a |
Shell large, more than 200 mm. The anterior and posterior wings developed. Teeth large |
Cristaria |
| b |
Shell medium, often less than 100 mm. Wing not very much developed. Teeth thin or unclear |
4 |
| 4a |
Shell tongue-shaped, dorsal margin oblique, ventral margin straight |
Pilsbryoconcha |
| b |
Shell oval or trapezoidal, dorsal margin moderately straight, teeth long and thin edge-shaped |
Pletholophus |
| 5a |
Shell with anterior and posterior wings developed. |
6 |
| b |
Shell without wing |
7 |
| 6a |
Shell narrow, boat or oval-shaped, caudal part pointed or gradually pointed |
Hyriopsis |
| b |
Shell broad, oval, caudal part amputated |
Sinohyriopsis |
| 7a |
Long narrow shell, length 3-5 times the height |
8 |
| b |
Shell has a length of no more than twice the height |
9 |
| 8a |
Shell arrow-shaped, caudal part gradually pointed |
Lanceolaria |
| b |
Shell finger-shaped, anterior part small, posterior part excessively large |
Solenaia |
| 9a |
Shell small in size |
10 |
| b |
Shell medium or large |
11 |
| 10a |
Height greater than 1/2 the length, shell nearly oval |
Unionetta |
| b |
The length equal about two times height |
Nodularia |
| 11a |
Shell askew trapezoidal shape |
Trapezoideus |
| b |
Shell ellipse |
12 |
| 12a |
Apex part low, located in 1/2 of the length from tip of shell |
Ptychorhynchus |
| b |
Apex located in 1/3-1/4 of the length from anterior part of shell |
13 |
| 13a |
Shell elongated ellipsoidal |
Pseudodon |
| b |
Apex located in 1/4-1/5 of the length from anterior part of shell |
14 |
| 14a |
Shell knife-shaped |
Oxynaia |
| b |
Shell elongated oval |
15 |
| 15a |
The back part pointed. Shell length 2.5-3.5 times the height |
Ensidens |
| b |
The back part round |
16 |
| 16a |
Shell ovoid, length 1.5-1.8 times the height. |
Contradens |
| b |
Shell ear-shaped |
17 |
| 17a |
Shell moderately parallelogram, a right angle formed by posterior margin and ventral margin. Pseudo-cardinal tubercle |
Protunio |
| b |
Shell thick, solid |
18 |
| 18a |
Shell moderately circular, apex far from anterior part. Shell larger 200 mm |
Chamberlainia |
| b |
Shell short, apex nearly anterior part. Shell medium size, length less than 100 m |
Cuneopsis |
Genus Contradens Haas, 1913
Key to species in Vietnam
| 1a |
Shell parallelogram |
Contradens fultoni |
| b |
Shell wedge-shaped or moderately oval |
2 |
| 2a |
Shell elongated wedge. Apex hightly convex, located near anterior part, about 1/4 the length of the shell |
Contradens tumidula |
| b |
Shell short moderately oval. Apex slightly convex, located near centre, about 1/3 length of the shell |
Contradens crossei |
Genus Cristaria Schumacher, 1817
Key to species in Vietnam
| 1a |
Shell short, posterior margin of wing straight. Anterior margin continuously connected to apex forms dorsal margin oblique |
2 |
| b |
Shell long, posterior margin of wing moderately concave, anterior margin of wing not continuously connected to apex to form dorsal margin straight |
3 |
| 2a |
Shell thick, shortly oval, ventral margin round, nacre yellow white color |
Cristaria plicata |
| b |
Shell thin, elongated oval, ventral margin concave, nacre green white |
Cristaria truncata |
| 3a |
Shell thin, posterior margin very developed, green or black brown color. |
Cristaria bialata |
| b |
Shell thick, posterior not developed, black-brown color |
Cristaria herculea |
Genus Hyriopsis Conrad, 1853
Key to species in Vietnam
| 1a |
Shell narrow, boat-shaped, rostrum developed |
Hyriopsis bialatus |
| b |
Shell oval, rostrum not developed |
Hyriopsis delaportei |
Genus Lanceolaria Conrad, 1853
Key to species in Vietnam
| 1a |
Shell elongated narrow (rate of L/h #5) |
2 |
| b |
Shell short, wide (rate of L/h #3) |
4 |
| 2a |
Posterior pointed. Shell surface with tubercles and axial edges |
3 |
| b |
Shell with posterior round, short. Shell surface without tubercles and edges |
Lanceolaria laevis |
| 3a |
Shell narrow, posterior pointed. The point moved to ventral margin |
Lanceolaria grayii |
| b |
Shell few narrow, posterior moderately pointed. The point in centre |
Lanceolaria gladiola |
| 4a |
Surface without tubercles and edges in posterior. Ventral margin moderately concave |
Lanceolaria bilirata |
| b |
Surface with tubercles and edges in posterior. Ventral margin straight |
Laceolaria fruhstorferi |
Genus Nodularia Conrad, 1853
Key to species in Vietnam
| 1a |
Shell long (L/h > 2). Dorsal margin straight. Hinge and teeth thin, inner shell bed deep |
Nodularia douglasiae |
| b |
Shell short (L/h < 2). Dorsal margin convex. Hinge and teeth rather thick, inner shell shallow |
Nodularia dorri |
Genus Oxynaia Haas, 1913
Key to species in Vietnam
| 1a |
Apex part low. Shell elongated narrow, length 2 times longer than height. Posterior point located in middle |
Oxynaia micheloti |
| b |
Apex part rises up, passed dorsal margin. Shell short, height 1/2 time more than length |
2 |
| 2a |
Shell knife-shaped, posterior point located nearly dorsal of shell |
Oxynaia jourdyi |
| b |
Shell moderately oval, wide, posterior point removes to ventral part |
Oxynaia diespiter |
Genus Physunio Simpson, 1900
Key to species in Vietnam
| 1a |
The length of shell often longer than 60 mm. Shell near parallelogram, anterior moderately pointed, apex highly raised up, located in centre of dorsal margin. Nacre blue-white color |
Physunio superbus |
| b |
The length of shell often shorter than 60 mm. Shell oval, anterior round. Apex low, located nearly anterior part. Nacre yellow-white with blue colour |
Physunio micropterus |
Genus Pilsbryoconcha Simpson, 1900
Key to species in Vietnam
| 1a |
Shell moderately inflated, thick, ellipse, rate of L/h > 2 (the height smaller than length). Wing not very developed. Ventral margin rather concave in the middle |
2 |
| b |
Shell thin, flatted, tongue-shaped, rate of L/h < 2. Wing developed. Caudal part regularly round, ventral margin regularly incurved |
Pilsbryoconcha compressa |
| 2a |
Shell moderately convex, thick |
Pilsbryoconcha exilis |
| b |
Shell moderately flatted, thin |
Pilsbryoconcha lemeslei |
Genus Pletholophus Simpson, 1900
Key to species in Vietnam
| 1a |
Shell thin, oval or trapezoid, the rate of L/h < 1. Posterior point in middle, ventral margin curved |
Pletholophus swinhoei |
| b |
Shell thick, elongated trapezoid or ovate, posterior point moves to ventral margin |
2 |
| 2a |
Shell elongated trapezoid, dorsal margin straight, the rate of L/h > 1. Ventral margin straight or round. Shell brown-yellow color |
Pletholophus discoideus |
| b |
Shell ovate, dorsal margin curved, ventral margin round, the rate L/h # 1. Shell black-brown or green-brown color |
Pletholophus inangulatus |
Genus Pseudodon Gould, 1844
Key to species in Vietnam
| 1a |
Shell short, the rate of L/h <2 |
2 |
| b |
Shell long, narrow, ellipsoidal, rate of L/h >2 |
3 |
| 2a |
Short moderately oval, concave mark on apex deep. Apex located on 1/3 of dorsal margin from anterior |
Pseudodon thompsoni |
| b |
Shell egg-shaped, concave mark on apex shallow. Apex located on 1/4 of dorsal margin from anterior |
Pseudodon inoscularis |
| 3a |
Posterior dorsal with range of oblique wrinkles running to posterior part. Nacre blue-white color |
Pseudodon resupinatus |
| b |
Posterior dorsal without range of oblique wrinkles. Nacre pink-white color |
Pseudodon mouhotii |
Genus Sinanodonta Modell, 1944
Key to species in Vietnam
| 1a |
Oval shell, the length is only one and half the height. Apex inflated pass dorsal margin |
Sinanodontajourdyi |
| b |
Shell elongated oval, the length about two times longer than the height. Apex low, not exceed dorsal margin |
Sinanodonta elliptica |
Genus Trapezoideus Simpson, 1900
Key to species in Vietnam
| 1a |
Shell thin, flated, obliquely trapezoidal. Apex placed in the fourth of dorsal margin |
Trapezoideus exolescens |
| b |
Shell solid, moderately trapezoidal. Apex placed in the third of dorsal margin |
Trapezoideus comptus |
Family AMBLEMIDAE RAFINESQUE, 1820
Key to genera in Vietnam
| 1a |
Shell small size, with oblique edges |
2 |
| b |
Shell large or medium size, without oblique edges 3 2a. Shell peanut-shaped, anterior round, with oblique edges on almost surface of shell |
Scabies |
| b |
Shell short grapefruit pips shaped, anterior obtuse, with oblique edges on the centre of shell only |
Diaurora |
| 3a |
Shell very thick, foot-shaped, ventral margin concave, apex far from anterior part of shell. Surface of shell with grooves |
Gibbosula |
| b |
Shell moderately thick, not foot-shaped, ventral margin gradually convex, apex nearly anterior part. Surface of shell with tubercles and grooves |
Lamprotula |
Genus Lamprotula Simpson, 1900
Key to species in Vietnam
| 1a |
Shell boat-shaped, elongated narrow, ventral margin straight, surface moderately smooth, with some tubercles in nearly apex |
Lamprotula bazini |
| b |
Shell wide, circular or elongated. Surface with many tubercles and striae |
2 |
| 2a |
Shell shortly circular. Apex located on the end of shell anterior |
3 |
| b |
Shell long elliptical, or oval |
5 |
| 3a |
Surface of shell with 2 edges in the middle from apex to posterior. Shell leaf-shaped, posterior pointed |
Lamprotula blaisei |
| b |
Surface of shell without edges middle. Shell with posterior round |
4 |
| 4a |
Shell moderately circular, with tubercles on almost surface. Shell black-brown color. |
Lamprotula nodulosa |
| b |
Shell shortly oval, with tubercles concentrated in apex part. Shell red-brown color |
Lamprotula liedtkei |
| 5a |
Shell elongated ellipsoidal. Shell surface without or few tubercles and striae |
Lamprotula caveata |
| b |
Shell widely oval. Shell surface with tubercles and striae, ranged in form “Ầ” |
Lamprotula leai |
Family CORBICULIDAE/CYRENIDAE GRAY, 1847
Key to genera in Vietnam
| 1a |
Surface without concentric ribs, length of shell more than 45 mm |
Geloina |
| b |
Surface of shell with concentric ribs, length less than 45 mm |
Corbicula |
Genus Geloina Gray, 1842
Key to species in Vietnam
| 1a |
Shell medium in size, moderately triangular |
2 |
| b |
Shell large, nearly circle |
Geloina coaxans |
| 2a |
Shell near triangular, moderately circle, approximately as high as long |
Geloina bengalensis |
| b |
Skewed triangular shell, length clearly greater than height |
Geloina expansa |
Genus Corbicula Mühlfield, 1811
Key to species in Vietnam
| 1a |
Shell surface with very thin edges, closed |
2 |
| b |
Shell surface with rough edges, ranked sparsely |
5 |
| 2a |
Shell large in size, length more than 30mm, lemon-yellow colour. Caudal part round |
Corbicula luteola |
| b |
Shell medium 20-30 mm |
3 |
| 3a |
Shell medium (20-22 mm), lower triangular. Posterio part rather long, oblique |
Corbicula leviuscula |
| b |
Shell medium (22-30 mm) |
4 |
| 4a |
Shell elongated oval. Anterior and posterior parts of equal |
Corbicula lamarckiana |
| b |
Shell egg-shaped, yellow grey or black-green-grey. Anterio and posterior extended |
Corbicula fluminea |
| 5a |
Shell equilateral triangle, black-violet color, posterior margin amputated |
Corbicula bocourti |
| b |
Apex obtuse and rise up |
6 |
| 6a |
Shell pear-shaped, growth lines ranked non regularly |
Corbicula moreletiana |
| b |
Apex pointed, rise up like rostrum |
7 |
| 7a |
Shell circular, growth lines ranked regularly |
Corbicula cyreniformis |
| b |
Shell thin, moderately convex |
8 |
| 8a |
Shell red-brown colour, posterior margin round. Shell surface with rough edges, ranked sparsely |
Corbicula baudoni |
| b |
Shell thick, flatted. Apex eroded |
9 |
| 9a |
Shell surface with growth lines, ranked sparsely, lemon yellow color, posterior margin round |
Corbicula blandiana |
| b |
Shell ellipsoidal shape |
10 |
| 10a |
Shell surface with rough growth lines, red-brown or black color, posterior margin formed comer below |
Corbicula tenuis |
| b |
Shell nearly triangle, oval or egg-shaped |
11 |
| 11a |
Shell thick, very convex, black-brown color, ventral margin round |
Corbicula siamensis |
| b |
Shell equilateral triangle |
12 |
| 12a |
Shell slitghtly thick, rather convex, yellow-brown color, ventral margin curved heart-shaped |
Corbicula lydigiana |
| b |
Shell nearly triangle, slightly rounded, slightly flattened |
13 |
| 13a |
Shell brown-green, yellow-green, or yellow-brown color. Nacre violet-white color |
Corbicula solidula |
| b |
Shell oval |
14 |
| 14a. |
Shell roundly oval, chestnut color. Nacre green white color |
Corbicula castanea |
| b |
Shell shortly oval, black brown color. Nacre pink-violet color |
Corbicula messageri |
