This research has been carried out in Thuan Chau District in Son La Province (Northwest region of Vietnam) from May, 2010 to December, 2013. A survey of this region showed that there are 71 species and subspecies, belonging to 45 genera, 18 families and 2 subclasses of terrestrial snails living in this region.
Trang 1This paper is available online at http://stdb.hnue.edu.vn
COMPOSITION AND DISTRIBUTION OF TERRESTRIAL SNAILS
(Gastropoda: Mollusca) IN THUAN CHAU DISTRICT,
SON LA PROVINCE, VIETNAM
Do Duc Sang1 and Do Van Nhuong2
1Faculty of Biology, Tay Bac University
2Faculty of Biology, Hanoi National University of Education
Abstract. This research has been carried out in Thuan Chau District in Son La
Province (Northwest region of Vietnam) from May, 2010 to December, 2013 A
survey of this region showed that there are 71 species and subspecies, belonging
to 45 genera, 18 families and 2 subclasses of terrestrial snails living in this
region Snails of the Pulmonata subclass vary in number with 45 species, making
up 63.38% of all species In the Prosobranchia subclass there are 26 species,
making up 36.62% of the total number of species Terrestrial snails in Thuan Chau
district are most diverse in terms of family and genera with the Cyclophoridae,
Ariophantidae, Camaenidae, Subulinidae and Clausiliidae families dominating
The snails are distributed mainly in forests (69 species) and limestone mountain
areas (44 species) Fewer species were found living on agricultural fields than in
forests and limestone mountain areas (26 species) Species composition differs
with elevation with Tortaxis sp., Oospira abstrusa, Oospira smithi, Alycaeus
requiescens and Cyclotus sp being found only at elevations greater than 1000
meters
Keywords:Gastropoda, Terrestrial snails, species composition, distribution, Thuan
Chau District, Son La Province
1 Introduction
Thuan Chau is a district in the northwestern Son La Province Its geographic coordinates are 21◦12’-21◦41’N, 103◦20’-103◦59’E It is bordered by Quynh Nhai district
to the north, Son La city and Muong La District to the east, Song Ma and Mai Son Districts to the South and with Dien Bien Province to the West It covers a total area Received February 12, 2014 Accepted May 5, 2014.
Contact Do Duc Sang, e-mail address: doducsangdhtb@gmail.com
Trang 2many valleys, basins and alternating mountains with an average elevation of 650 meters More than 85% of the area has a slope of at least 25 degrees Thuan Chau is also the beginning point of the Son La plateau which extends to Yen Chau District
Terrestrial snails play an important role in the ecosystem They are considered to
be an invertebrate biodiversity indicator and an index of disorder of the plant litter layer Terrestrial gastropods in Vietnam have been studied since the mid-nineteenth century but have been fully examined only in parts of the Northwest, Northeast, Southwest Highlands and coastal islands [7] The data collected on terrestrial gastropods in Thuan Chau District contributes to the pool of knowledge regarding biodiversity, exploitation and conservation
in the highland regions
The region investigated has a tropical climate which is characterized by two seasons: a long dry season from April to September and a wet season from October to March Precipitation ranges from 1.200 - 1.600 mm per year, falling primarily in June, July and August The evaporation rate is about 800 mm per year The average annual temperature is 21.4◦C The average humidity is about 81% There are many streams which are tributaries of the Ma and Da Rivers [7]
In the region investigated, there is a natural reserve - Copia - with a total area of 17.000 ha in which is found approximately 609 plant species belonging to 406 genera and 149 families These plants are distributed in temperate forests, coniferous forests, plantation forests and savanna with most trees of the subfamily Bambusoideae and pine
forests (Lycopodiella) [11].
2 Content
Samples were collected from May, 2010 to December, 2013 along the main routes to the Co Ma, Phong Lai and Chieng Khoang Townships Along these routes are limestone, forest on limestone, plantation forest, cultivated area and cultivated area adjacent to forest
Qualitative samples were collected in all habitats Small samples are separated by
a sieve with a 1 - 8 mm mesh Quantitative samples were collected in areas 1 m2 in size Samples were shaped and conserved in methanol Samples that consisted only of shells were conserved in a dry condition The total amount of analyzed sample material was 6.538 These samples were then stored at the Terrestrial Animals Research Center of the Hanoi National University of Education
Terrestrial snails were identified referring to Bavay & Dautzenberg [1, 2], Dautzenber & Fishcher [3, 4], Fisher [5] and Kobelt [15] In addition, the samples were compared with Vermeulen’s collection (2003) which is stored at the Institute of Ecology and Biological Resources Taxons were arranged according to Schileyko [12]
Trang 3Figure 1 Location of samples collected in Thuan Chau District
* Species composition of terrestrial snails in the studied regions
Terrestrial snails collected in Thuan Chau were of the subclasses Prosobranchia and Pulmonata Of the Prosobranchia subclass there were 26 species of 13 genus and 4 families (Cyclophoridae, Diplommatinidae, Helicinidae and Pupinidae) Of the Pulmonata subclass were found 45 species belonging to 32 genera and 14 families (see Table 1)
Table 1 Species composition of terrestrial snails and their distribution
according habitat and elevation in Thuan Chau District
For Li.
mo Pl fo.
Below 600
600 -1000
Over 1000
Subclass
PROSOBRANCHIA
Order
ARCHITAENIOGLOSSA
CyclophoridaeGray, 1847 14.45 4.10 3.36 2.77 11.04 8.11
1 Alycaeus anceyiMabille, 1887 0.61 0.05 0.52 0.14
2 Alycaeus requiescens1887 Mabille, 0.05 0.05
3 Chamalycaeus fracterculus (B.
Trang 44 Chamalycaeus rathouisianus
6 Cyclophorus diplochius(M¨oll.,
7 CyclophorusM¨oll., 1874 martensianus 0.15 0.15
8 Cyclophorus siamensis
10 Dioryx pocsiVarga, 1972 0.38 0.11 0.03 0.15 0.09 0.28
11 Japonia1901) diploloma (M¨oll., 0.41 0.17 0.03 0.11 0.32 0.18
12 Pterocyclos bethaed’Ham., 1887 Daut et 4.19 0.75 0.32 0.96 1.36 2.94
13 Pterocyclos marioni1898 Ancey, 3.93 1.67 0.50 0.11 3.70 1.35
14 Scabrina laciniata (Heude,
Diplommatinidae Pfeiffer,
16 Diplommatina electa1895) (Fulton, 0.50 0.05 0.55
17 DiplommatinaSaurin, 1853 rotundata 0.14 0.14
Order NERITOPSINA
18 Geotrochatella jourdyi Daut.,
19 Pseudopomatias fulvus M¨oll.,
20 Pseudopomatiassp 0.43 0.69 0.03 0.08 0.31 0.76
21 Pupina anceyiB et D., 1899 0.50 0.09 0.41
22 Pupina brachysoma Ancey,
23 Pupina exclamationis Mabille,
24 Pupina illustrisMabille, 1887 1.01 1.01
Trang 526 Pupinasp.2 0.09 0.03 0.05 0.08
Subclass PULMONATA
Order
STYLOMMATOPHORA
AchatinidaeSwainson, 1840 0.05 0.08 1.07 0.06 1.09 0.05
27 Achatina fulicaFérussac, 1822 0.05 0.08 1.07 0.06 1.09 0.05
Ariophantidae
Godwin-Austen, 1888 20.60 4.51 0.84 1.80 15.86 8.44
28 Elaphroconcha hageni1966) (Weber, 0.69 0.31 0.05 0.03 1.01
29 Hemiplectasp 0.26 0.55 0.08 0.47 0.29 0.12
30 Macrochlamys(Martens, 1864) amboiensis 0.26 0.06 0.17 0.15
31 Macrochlamys despecta
32 Megaustenia(Gould, 1858) imperator 3.03 1.06 0.58 0.28 2.55 1.84
33 Microcystinasp 10.75 1.58 0.14 0.61 11.82 0.03
BradybaenidaePilsbry, 1939 4.34 2.69 5.61 0.37 9.94 2.65
34 Aegista packhaensisDaut., 1908) (Bav et 0.58 0.05 0.03 0.60
35 Bradybaena jourdyi1886) (Morlet, 3.03 1.51 5.54 0.28 9.35 0.46
36 Plectotropis dasytrichaDaut., 1908) (Bav et 0.73 1.13 0.07 0.09 0.26 1.59
37 AmphidromusFulton, 1899 dautzenbergi 0.61 0.29 0.11 0.03 0.76
38 Camaena billiti(Fischer, 1898) 0.29 0.08 0.03 0.40
39 Camaena duportiDaut., 1908) (Bav et 0.34 0.29 0.05
40 Camaena gabriellae (Daut et
41 Camaena vanbuensis1896 Smith, 1.06 2.13 0.11 0.05 0.31 2.94
42 Camaena vayssierei (Bav et
44 Moelendoffia depressispira(B.
45 Trachia marimbertiDaut., 1900) (Bav et 5.61 0.93 0.14 0.49 2.71 3.49
Trang 646 Trachia nasuta (Bav et Daut.,
47 Hemiphaedusa cervicalis(Bav.
48 Oospira abstrusa1970) (Szekeres, 0.05 0.05
49 Oospira smithi Maassen et
50 Phaedusa1887) lypra (Mabille, 0.15 0.03 0.18
51 Phaedusa micropaviei
52 Phaedusa1892) paviei (Morlet, 0.38 0.06 0.32
53 Coccoderma(Bav et D., 1912) macrostoma 0.08 0.08
54 Kaliella ordinariaAncey, 1903 0.20 0.03 0.14 0.09
55 Kaliella subelongataDaut., 1912 Bav et 0.18 0.09 0.20 0.08
Glessulidae Godwin-Austen,
56 Glessula pavieiMorlet, 1892 1.85 0.31 0.06 0.64 0.57 1.01
Helicarionidae Bourguignat,
57 Sesara1859) diplodon (Benson, 0.06 0.15 0.15 0.06
Hypselostomatidae Zilch,
58 Boysidia hupeana1901) (Gredler, 0.15 0.03 0.03 0.15
59 Hypselostoma crossei1891) (Fischer, 0.26 0.05 0.31
Plectopylidae M¨ollendorff,
60 Gudeodiscus giardi1898) (Fischer, 2.69 0.61 0.21 1.87
61 Gudeodiscus multispira(M¨oll.,
Trang 762 Haploptychius diespiter
63 Huttonella bicolor1834) (Hutton, 0.12 0.12
SubulinidaeFischer et Crosse,
65 Lamellaxis gracilis (Hutton,
66 Prosopeas excellensDaut., 1908 Bav et 1.42 1.42
68 Subulina octona1792) (Bruguiere, 0.28 0.02 0.29
69 Tortaxis elongatissimusBav et
Trochomorphidae
71 Videna timorensis1867) (Martens, 1.36 0.32 0.12 0.18 0.86 0.76
For.: Forest; Li mo.: Limestone mountain; Pl fo.: Plantation forests
Species composition of the subclass Prosobranchia was relatively diverse, accounting for 36.62% of the total number of species Species composition was dominated
by subclass Pulmonata at 63.38% This proportion matches Vermeululen’s results (2003)
in which was found the in northern Vietnam, the Pulmonata accounted for 2/3 of all species [14]
Genus and species diversity in the family Cyclophoridae was 14 species, (19.72% of all species found), in Camaenidae it was10 species (14.08%), Pupinidae 8 species (11.27%), Ariophantidae 6 species (8.45%), Clausiliidae 6 species (8.45%) and Subulinidae 6 species (8.45%) Other families were less diverse Those families of snails found in the study region have also been identified in the following northern regions of Vietnam: Xuan Son (Phu Tho), Tam Dao (Vinh Phuc), Tay Trang (Dien Bien), Pu Luong (Thanh Hoa), Cam Pha, Ha Long (Quang Ninh) and Cuc Phuong (Ninh Binh) [6, 8, 9, 14] The diverse species composition of Prosobranchia indicates an ability to adapt to the
highland and monsoon subtropical climate Snails of the species Alycaeus, Cyclotus and Pterocyclos(Cyclophoridae) are commonly distribution in Laos, Dien Bien and from Son
La to Lang Son This horizontal distribution shows the ability of his group to adapt to the South east Asian highlands
Trang 8Ariophantidae, Camaenidae, Subulinidae and Clausiliidae This species diversity shows
an adaptability to the terrestrial environment, with the genera Macrochlamys, Camaena, Haploptychius, Phaedusa and Trachia being distributed widely in the Southeast Asia,
including a part of Southern China Presently unidentified are 12 species, 16.90% of the species found, which may or may not be new species or subspecies
Comparing the data on terrestrial snails found in the Thuan Chau District with other regions in northern Vietnam shows a species differentiation The number of species that have characteristics as described in data on snails found in Tam Dao, Cuc Phuong and
Pu Luong National Parks, and Phu Ly, Cam Pha and Tay Trang is 7, 30, 22, 8 and 13, respectively (see Table 2)
Table 2 Species composition of terrestrial snails of Thuan Chau
compared with species composition of other regions
Species composition Same species composition
Species Genera Families Species Genera Families
(a): Hoang Ngoc Khac et al (2012) [6];(b): Vermeulen & Maassen (2003) [14];
(c): Do Van Nhuong et al (2012) [9]
* Distribution of terrestrial snails
Habitat sensitive
Forests and limestone mountain areas are the habitats that have the greatest species diversity in studied region (69 species, 97.18% of the total, and 44 species, 61.97%, respectively) The least species composition is seen in plantations adjacent to forests (26 species, 36.62% of the total) Forests with a thick plant litter layer, high humidity and high forest coverage rate offer a good living environment with ample food for snail groups that preferring a damp environment (Cyclophoridae, Camaenidae, Ariophantidae and Clausillidae)
In the limestone mountains located along National Street No 6, crossing Thuan Chau District and a part of Son La highlands, are many caves, valleys and gullies, which are suitable living places for small organisms the prefer a damp environment (Euconulidae, Pupinidae, Subulinidae, Streptaxidae, Hypselostomatidae and Diplommatinidae) Many terrestrial snails consume algae living on stones in the limestone
Trang 9mountain areas making this a suitable environment for these organisms.
Plantations which are adjacent to forested land, upland rice fields and perennial crop fields comprise a significant area in Thuan Chau Due to human impact, the forest coverage rate, humidity, plant litter layer composition and soil characteristics have been strongly altered in a manner which is disadvantageous to these organisms with a resultant decrease in species composition Genera which have been able to adapt to the environment
that has been altered by human activities are the Pterocyclos, Bradybaena and Achatina Species that are widely distributed in all three habitats are Achatina fulica, Cyclophorus siamensis, Pterocyclos berthae, Haploptychius diespiter, Megaustenia imperator, Macrochlamys despecta, Bradybaena jourdyi, Camaena vanbuensis, Glessula paviei and Videna timorensis.
Elevation sensitive
Locations where samples were collected were divided into two groups: those with
6 communes in the southwestern part of the investigated region that has an elevation of more than 1000 meters, and the rest of the investigated region Forest coverage is relatively extensive Species diversity of the high elevation group was great with 56 species, 78.87%
of the total, with the families Ariophantidae, Cyclophoridae, Camaenidae and Subulinidae being found in abundance
Of the second group, found at an elevation below 1000 meters (average 650 meters), the forests have been altered by human activity with plantation and fallow land being abundant and species diversity being less with 34 species (47.89% of the total) being identified The families Plectopylidae, Streptaxidae, Euconulidae, Pupinidae were most abundant
3 Conclusion
It was found that there are 71 species of terrestrial snails in Thuan Chau District, belonging to 45 genera, 18 families and 2 subclasses (Prosobranchia, Pulmonata) The Pulmonata are most diverse with 45 species, 63.38% of all species The Prosobranchia were least diverse with only 26 species, 36.62% of the total The families Cyclophoridae, Ariophantidae, Camaenidae, Subulinidae, Clausiliidae are most prevalent
The terrestrial snails in Thuan Chau district are found mainly in forest (69 species) and limestone mountain areas (44 species) The number of species living in agricultural fields is less than in forest and limestone mountain areas (26 species) Species distribution
at an elevation greater than 1000 meters differs from species distribution at lower
elevations Tortaxis sp., Oospira abstrusa, Oospira smithi, Alycaeus requiescens and Cyclotussp were found only at an elevation of more than 1000 meters
Trang 10[1] Bavay, A & Dautzenberg, P., 1899a Description de coquilles nouvelles de l’Indo-Chine J de Conch., 47(1): 28-55, pl 1-3.
[2] Bavay, A & Dautzenberg, P., 1899b Description de coquilles nouvelles de l’Indo-Chine (Suite) J de Conch., 47(4): 275-296, pl 12.
[3] Dautzenberg P & Fischer, H., 1905a Liste des mollusques récoltés par M Le Capitanine de Frégate Blaise au Tonkin et description d’espèces nouvelles J de
Conch., 53 (2), pp: 85-234
[4] Dautzenberg P & Fischer, H., 1905 Description d’espeges nouvelles Extraif du
Journal de Conchy Biologie, Vol LIII, I Paris 1905 p 86-216
[5] Fischer P., 1891 Catalogue et distribution gèographique des mollusques terrestres, fluviatilies et marins d’une partie de l’Indo-Chine (Siam, Laos, Cambodge, Cochinchine, Annam, Tonkin) Bull Soc., Hist Nat Autum, pp 1-186.
[6] Hoang Ngoc Khac, Do Van Nhuong, Nguyen Thi Cay, Tran Thap Nhat, 2012
Land Snails (Gastropoda) in Tam Dao National Park, Vinh Phuc Province, Vietnam.
Journal of Biology, 34(3), pp: 317-322
[7] Vu Tu Lap, 2012 Natural Geography of Vietnam Publisher of Hanoi University of
Education, pp: 11-236
[8] Do Van Nhuong, Hoang Ngoc Khac, Khong Thuy Anh, 2010 Preliminary data on Land Snails (Gastropoda) in Xom Du village, Xuan Son National Park, Phu Tho Province Journal of Biology, 32(1), pp: 13-16.
[9] Do Van Nhuong, Dinh Phuong Dung, 2012 Data on land Snails (Gastropoda) in the Tay Trang area, Dien Bien Province Journal of Biology, 30(4), pp: 397-404 [10] Do Van Nhuong, Tran Thap Nhat, 2012 Preliminary data on Land Snails (Gastropoda) in the Son La City area Journal of Science of the Hanoi University of
Education, 57(3), pp: 99-109
[11] Do Duc Sang, Do Van Nhuong, 2013 Data on Land Snails (Gastropoda) in the Copia Nature Reserve, Son La Province National conference on Ecology and
Biological Resources, pp: 642-648
[12] Schileyko A.A., 2011 Check list of terrestial pulmonate molluscs of Vietnam (Gastropoda: Stylommatophora) Ruthenica, Vol 21, No.1, pp: 1-68.
[13] Dang Ngoc Thanh, 2008 Overview of species composition of Land Snails fauna of Vietnam Journal of Biology, 30(4), pp: 1-15.
[14] Vermeulen J.J., W J.M Maassen, 2003 The non-marine Mollusk fauna of the Pu Luong, Cuc Phuong, Phu Ly and Ha Long regions in northern Vietnam A survey for
the Vietnam Program of FFI (Flora and Fauna International) (unpublished report):
27 pp
[15] Wilhelm Kobelt, 1902 Cyclophoridae Verlag von R Friedlander und Sohn, pp:
1-539