Occurrence of Aquatic Pulmonate Snails in Some Areas of Yangon and Bago Region

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1 Universities Research Journal 2011, Vol. 4, No. 2 Occurrence of Aquatic Pulmonate Snails in Some Areas of Yangon and Bago Region Tin Moe Win 1, Khin War War 2, Soe Moe Tun 3 and Maung Maung Gyi 4 Abstract Occurrence of aquatic pulmonate snails from some areas of Yangon and Bago Region was investigated. A total of ten species of aquatic pulmonate snails were collected during the study period of June, 2009 to December, They were widely distributed in study areas and found to inhabit in the stagnant or sluggish water at low altitudes of lakes, ponds, canals, marshes and ditches. Key words: occurrence, aquatic pulmonate snails, Yangon and Bago Region. Introduction The vast majority of mollusks, more than 80% are snails (Panha and Burch, 2005). Of these 31, ,000 are marine, 14,000-35,000 terrestrial and about 5,000 freshwater species (Abbott, 1989; Seddon, 2000). Fresh water mollusks comprise a relatively small number of bivalves, prosobranchs and pulmonate gastropods. Aquatic pulmonate snail which shell delicate with a conical spire and large aperature. They migrated to fresh water from the land, using the mantle cavity as a lung and coming to the surface to breath air (Pfleger,1990). Materials and methods Specimens were collected from various places of Yangon and Bago environs from June2009 to December Identification and classification was made according to Dall (1904) and Pfleger (1990). Possible habitats of aquatic pulmonates snail as lake, ponds, canals, marshes and ditches were described. Their conditions of habitats were recorded. Dead specimen (only shell) were thoroughly washed, dried and kept in small glass bottles. 1. Lecturer, Department of Zoology, University of Yangon 2,3 Assistant Lecturer, Department of Zoology, University of Yangon 4. Professor (Head), Dr., Department of Zoology, University of Yangon

2 110 Universities Research Journal 2011, Vol. 4, No. 2 Results A total of ten species of aquatic pulmonate snails of three genera under three families were recorded. Table. 1. Systematic position of recorded aquatic pulmonate snails Phylum - Mollusca Calss - Gastropada Subclass - Pulmonata Order - Basommatophora No. Family Genus Species 1 Physidae Physa Physa acuta Physa sp 1 Physa sp 2 2 Lymnaeidae Lymnaea Lymnaea sp 1 Lymnaea sp 2 Lymnaea sp 3 Lymnaea sp 4 3 Planorbidae Planorbis Planorbis sp 1 Planorbis sp 2 Planorbis sp 3 Descriptions of aquatic pulmonate snails Physa acuta Draparnaud, 1805 The shell was a pointed ovoid with a sharply conical spire, thin but relatively strong walls. Sinistral. It was translucent, glossy and pale yellowish-brown in colour. There were five faintly convex whorls. 10 mm in height and 6 mm in width. The last whorls which was swollen and its sides were slightly compressed, narrowing at the base. The aperature was inversely auricular. Height of aperature was about two thirds of the height of shell. A straight sharp margin, which widens only in the columellar region, where it often formed a distinct flat white lip. They were found in

3 Universities Research Journal 2011, Vol. 4, No stagnant and gently flowing water, lakes, ponds, ditches and marshes of Insein, Inya lake and Bago (Plate I. A). Physa sp 1 The shell was sinistral, 10 mm in height and 6 mm in width, 5 whorls. It was ovoid shaped with a acute apex and conical spire. The shell was polished, semi-translucent and dark brown in colour. The last whorls expanded and narrowing at the base. Aperature was inversely auricular. Height of aperature was about two thirds of the height of shell. A spire shorter than the length of the aperature. The outer lip sharp, with a slight thicking internally, surface of the shell was microscopically striated. They were found in stagnant and gently flowing water, lakes, ponds, ditches and marshes of Insein, Inya lake and Bago (Plate I.B). Physa sp 2 The shell was subglobose-ovoid shape with short spire. Apex pointed and suture impressed. Sinistral. 12 mm in height and 8 mm in width, Height of the aperature was 9 mm. Whorls nearly 5, translucent, polished and yellowish brown in colour. The last whorls expanded and sculpture with mocroscopic spiral. Aperature was inversely auricular. A straight sharp margin which widens in columellar region, where it often distinct flat white lip. They were commonly found fresh water ponds and ditches (Plate I.C). Lymnaea sp 1 The shell was elongate-ovate, with a sharp pointed and short spire. The wall of the shell was extremely thin fragile, transparent and marked with irregular grooves.pale straw in colour. 15 mm in height and 7 mm in width. Height of aperature was 12 mm. 3.5 whorls, dextral. The aperature was slender and oval. The last whorls was as long as the shell. The callus on the body closely appressed, the outer lip flaring more or less, simple, sharp. They were found in Inya Lake (Plate I.D). Lymnaea sp 2 The shell was swollen and ovoid with conical spire. Suture impressed. It was relatively thick-walled, but fragile, polished slightly translucent. Dextral. 11 mm in height and 8 mm in width, 4.5 convex well rounded whorls, increased quite quickly, the last whorls was markedly swollen. The surface was transverse line present. The aperature was

4 112 Universities Research Journal 2011, Vol. 4, No. 2 inversely auriculate, it had simple and sharp margin. Columellar margin twisted and reflected. They were found in overgrown stagnant water at low altitudes (Plate.I.E). Lymnaea sp 3 The shell was ovoid formed, tumid whorls with a short conical spire. The wall of the shell was thin, fragile, translucent, polished and pale yellowish brown in colour. 10 mm in height and 7 mm in width. 4 rounded whorls. The last whorls was the largest, moderately expanded, and somewhat produced infront. The shell sculpture was transverse lines present. Dextral. The aperature was inversely auriculate. It has simple and sharp margin. Umbilicus was deep and partly hidden by the reflected pillar lip. The outer lip outwardly expanded. They were found in over grown stagnant water at low altitudes in Insein Township (Plate.I.F). Lymnaea sp 4 The shell was ovoid with pointed conical spire, thin, 9 mm in height and 6 mm in width, 4.25 whorls, the last whorl being the largest, moderately expanded. The shell was dark-brown in colour, translucent, sculpture with black fine spiral striation.suture impressed, Dextral.The aperature was inversely auriculate. The columellar margin twisted and reflected, whitish in colour. They were found in Bago Region (Plate.I.G). Planorbis sp 1 The shell was discoid, ultra-dextral, 12 mm in width and 5.5 mm in height, 4 whorls with gradually enlarging whorls, rounded above and below. The last whorls was suddenly expanded. The aperture was wide and ovally auriculate. The umbilical zone was deeply in drawn. The flattened apex was usually depressed below the upper level of the ultimate whorl. The shell sculpture was transverse line present. They were found in stagnant water of pond, lake and pool with vegetation in Insein Township (Plate.I.H). Planorbis sp 2 The shell was discoid and ultra-dextral with whorls, 6 mm in height and 11 mm in width. Its surface was transverse line present. The apex was pressed in whorls. The umbilical zone was deeply indrawn. The aperature was kidney-shaped. The margin was simple and sharp edged and widens somewhat at the top. It was yellowish brown in colour. They were

5 Universities Research Journal 2011, Vol. 4, No found in stagnant water of pond, lake and pool with vegetation in Insein Township (Plate.I.I). Planorbis sp 3 The shell was thickly discoid and ultra-dextral with 4.5 whorls, 6 mm in height and 13 mm in width, brown in colour. The flattened apex was usually depressed below the upper level of the ultimate whorl. The umbilical zone was deeply indrawn. The shell sculpture was transverse line present. The aperature was widely auriculate, sharp, slightly expanded. Gradually enlarging whorls but the last more expanded near the aperature. They were found in stagnant water of pond, lake and pool with vegetation in Insein Township (Plate.I.J). Distinctive account of aquatic pulmonate snails Physa spp were sinistral and ovoid shaped. Lymnaea spp were dextral, expanded last whorls, the outer lip flaring more or less simple sharp, normally without any vertical thickening. Physa spp and Lymnaea spp were richly found in over ground stagnant water of gently flowing water. Planorbis spp were shell discoid, ultra-dextral, gradually enlarging whorls rounded above and below. They were found in stagnant water of pond, lake and pool with vegetation which attached on the leaf surface. A. Physa acuta B. Physa sp 1 C. Physa sp 2 D. Lymnaea sp 1

6 114 Universities Research Journal 2011, Vol. 4, No. 2 E. Lymnaea sp 2 F. Lymnaea sp 3 G. Lymnaea sp 4 H. Planorbis sp1 I. Planorbis sp2 J. Planorbis sp3 Plate I. Aperatural and abaperature view of aquatic pulmonate snails Discussion A total of ten species of aquatic pulmonate snails were recorded from Yangon and Bago Region. These included three species each from family Physidae and Planorbidae, four species from Lymnaeidae. Pfleger (1990) stated that Physa spp were commonly known as bladder snails. The shell was sinistral with glossy thin walls. It was represented on all the continents. In the present study, Physa spp occurred widely distributed and common in all the study area. Pfleger (1990) also stated that the shell of Lymnaea was dextral and commonly known as pond snails. It was distributed all over the world. It included the great variability of the shell, due to the effect of different aquatic environments. In the present study, four species of Lymnaea were observed size varies and morphological differences of the shells. Dall

7 Universities Research Journal 2011, Vol. 4, No (1910) reprted that the actural size varies with the food supply and healthfulness of the environment. Size may be affected by habitat (Pfleger, 1990). Dall (1910) stated that the great majority of the species present the peculiarity of the whorls rising above the original apex, which becomes basal, the shell (apparently sinistral) thus becoming what had been called ultra-dextral. Shell of Planorbis spp were discoid and ultra-dextral. They were found in bed of water green. Pfleger (1990) stated that the family Planorbidae was represented all over the world. Some were tolerant of temporary habitats which dry up and are able to close the aperature of their shell with a whitish epiphragm and survived for several weeks until the pool fills again. They were commonly known as Ramshorn snails. They were found often among weed in flowing and still waters of rivers, canals and lakes. Freshwater mollusks species had been less affected by man, so there was less variation in species and widely distributed in study area. Acknowledgement Our special thanks go to Dr. Tin Aye Yi, Dr. Yin Win Tun and Ma Khin Myat Nwe for their specimens collection. References Abbott, T.R. (1989). Compendium of Land shells. American Malacogists, Inc., Melbourne. Dall, W.H., (1910). Land and freshwater Mollusks. Harriman Alaska Series Vol. XIII. 156pp. Panha, S. and Burch, J.B. (2005). An Introduction to the Microsnails of Thailand. Malacological review. Vol. 37/38:1-1. Pfleger, V. (1990). A field guide in colour to Mollusks. Blitz Edition.216 PP. Seddon, B.M. (2000). Molluscan Diversity and Impact of Large Dams. Prepared for thematic review II.1: Dams, Ecosyetem Functions and Environmental Resoration. IUCM Report.