Universities Research Journal 2011, Vol. 4, No. 2 Occurrence of Small Land Snail Bradybaena similaris (Ferussac, 1822) (Pulmonata: Stylommatophora) in Yangon Environs Khin War War 1, Tin Moe Win 2, Soe Moe Tun 3 and Maung Maung Gyi 4 Abstract Occurrence of small land snail Bradybaena similaris was investigated from different areas of Yangon Region during June, 2009 to December, 2010. Within a single species various morphological differences were observed among vary individuals. Color pattern of the shell was also varied. The colour of the shell was light brown or grayish-white. A few species had a red brown peripheral band. The different form of shell was recorded from juvenile snail to adult snail. They were widely distributed in bushy vegetation of mostly grass. Key words: Small land snail, Bradybaena similaris Yangon Region, morphological differences. Introduction A land snail is any of the many species of snail that live on land, as opposed to those that live in salt water and fresh water. Land snails have shell made of one part (univalve) and usually coiled into a spiral. The land snails are known as pulmonate, breath with a lung. Most pulmonates are land animals, most land snail generally require a damp environment (Pfleger, 1990). Materials and Methods Specimens were collected from home garden of Insein, University of Yangon Campus including the vicinity of Inya Lake and the environs of Myaypadaytha garden during the period from June2009 to December 2010. Identification and classification was made according to Naggs and Raheem, 2000 Cited in Vaught, 1989. 1,3. Assistant Lecturer, Department of Zoology, University of Yangon 2. Lecturer, Department of Zoology, University of Yangon 4. Professor (Head), Dr., Department of Zoology, University of Yangon
222 Universities Research Journal 2011, Vol. 4, No. 2 Results Systematic position of B. similaris. Phylum - Mollusca Calss - Gastropada Subclass - Pulmonata Superorder - Stylommatophora Superfamily - Helicoidea Family - Bradybaenidae Genus - Bradybaena Species - B. similaris, (Ferussac, 1822) Description The strong spherical shell with transverse lines faintly translucent, 5.5 whorls, elevation spiral, increase regularly and fairly rapidly in size. 12-14 mm in width and 9-11 mm in height. Suture impressed. Aperture was oblique and D-shaped. Peristome was expanded outwardly and relatively sharp. Rimately umbilicus. The colour of the shell was light brown or grayish-white. A few species had a red brown peripheral band which had 5 whorls with fairly elevated spiral. In juvenile, the shell was transparent, peristome very sharp and truncated aperture. They were widely distributed and common in bushy vegetation mostly grass and wall of damp places nearby vegetation. Polymorphism of the snail It was observed mostly in shape and colour. Besides whorls, spiral, shape and aperture of the snail were also found to vary among different individuals. The morphological character of specimen I was spherical shaped with elevation spiral and pale-brown in colour. It was common (60%) in the present study. The specimen II was spherical shaped with moderately elevated spiral and grayish white in colour. It was recorded the uncommon (30%).The specimen III was spherical shaped with fairly elevated spiral and pale-brown in colour with red-brown peripheral band which was rare (10%) and occurred only in University of Yangon Campus (Table 1, Plate 1, 2 and 3).
Universities Research Journal 2011, Vol. 4, No. 2 223 Distribution of B.similaris Specimen I and specimen II occurred in Insein, University of Yangon Campus and Myaypadaytha Garden. Specimen III occurred only in University of Yangon Campus (Table 2). Table 1. Distinct morphological characters which account for the polymorphic of B.similaris. No. Morphological characters Specimen I Specimen II Specimen III Common (60%) Uncommon(30%) Rare (10%) 1 Width 12-13 mm 12-14 mm 11mm 2 Height 11mm 11mm 9mm 3 Shape Spherical with moderately elevated spiral Spherical with elevated spiral Spherical with fairly elevated spiral 4 Colour Pale-brown Grayish-white Pale-brown with red-brown peripheral band 5 Whorls 5 5.5 5 6 Suture Moderately impressed Impressed Fairly impressed 7 Aperture D-shaped Widely D-shaped D-shaped Table 2. Distribution of B.similaris in study area No Specimen Insein University of Yangon Campus Myaypadaytha Garden 1 Specimen I 2 Specimen II 3 Specimen III - -
224 Universities Research Journal 2011, Vol. 4, No. 2 Plate 1 Apertural view of specimen Plate 2 Apical view of specimen I, II and III I, II and III Plate 3 Juvenile snail Discussion Within a single species of B. similaris, three different types of specimens were observed with the distinct morphological differences. Raheem and Naggs (2006) stated that the shells of some land-snail species can be highly variable in size, form and /or colour pattern. Mordan et.al (2003) reported that the shells of B. similaris were extremely variable in shape and polymorphic in colour, with or without variable numbers of longitudinal brown band. Their findings was coincided with the present study. Pfleger (1990) stated that a small land snail B. similar was known as bush snail. Mordan et.al (2003) stated that it was originally from Southeast Asia. It was now widely distributed in tropics. They attacked legumes and
Universities Research Journal 2011, Vol. 4, No. 2 225 may become sufficiently abundant to constitute a serious pest. It may be probably pest, they were widely distributed and common in bushy vegetation mostly grass. Pfleger (1990) also stated that the shell of a juvenile snail may be very different in its proportions from that of an adult of the same species. Shell growth occurred at the lip of the shell and the adult shells of some species show a thickened or expanded lip that is absent in juvenile. His finding was agreeable with the present study, the different form of shell was recorded from juvenile snail to adult snail. Acknowledgements We are deeply indebted to U Tin Myint Saw, Assistant Manager, Educational Zone, Myaypadaytha Garden, Myanmar Agriculture Service for his kind help. References Mordan, P, Naggs, F., Rananiana, K., Kumburegama, S., and Grimm, B.(2003). A guide to the pest and exotic gastropods of Srilanka. Naggs, F. and Raheem, D.(2000). Land snail diversity in SriLanka. The Natural History Museum London: 214pp Pfleger, V. (1990). A field guide in colour to Mollusks. Blitz Edition.216 PP. Raheem, D and Naggs, F.(2006). An Illustrated Guide to the Land Snails of SriLanka Natural Forest and Cultivated Habitats. Vaught, K.C.(1989). A classification of the living Mollusca (Eds. R. T. Abbott and K.J.Boss). Ameriacan Malacologists, Melbourne, Florida USA.