IDENTIFICATION KEY OF WEST BENGAL LEECHES ( ANNELIDA : HIRUDINEA )

As in animal kingdom every organism has a specific importance under non-chordate hfOUP, leeches have also great importance both in taxonomy and medicinal field. lalaukas the naJne of leech is in "Susruta", lalauka in "Mahabharata" Jaluka in Sanskrit, laru in Sindhi, and Juku in Nepali. Due to medicinal value and venomous quality leeches are becoming attractive to human beings, so many scientists are engaged to discover the leeches. Leeches are very important so far regulation of size and shape of the invertebrate communities is concerned. They, on way of sucking blood from cattle, reptiles, amphibians and fishes transmit the blood parasites and thereby inviting trypanosomiasis and helminthiasis in these animal groups. More than 549 species of leeches are reported from the world (Bondyopadhyay, P.K. and MandaI, C.K. 2006) of which about 63 species have so far been recored in Indian region. In West Bengal, however 28 species are now known to occur in varied ecological conditions from plains to the mountains, low to heavy rainfall areas and from river bed to ponds. Some species live permanently in water while others in dampy bushes under rotten leaves, bricks and stones.


INTRODUCTION
As in animal kingdom every organism has a specific importance under non-chordate hfOUP, leeches have also great importance both in taxonomy and medicinal field.lalaukas the naJne of leech is in "Susruta", lalauka in "Mahabharata" Jaluka in Sanskrit, laru in Sindhi, and Juku in Nepali.Due to medicinal value and venomous quality leeches are becoming attractive to human beings, so many scientists are engaged to discover the leeches.Leeches are very important so far regulation of size and shape of the invertebrate communities is concerned.They, on way of sucking blood from cattle, reptiles, amphibians and fishes transmit the blood parasites and thereby inviting trypanosomiasis and helminthiasis in these animal groups.
More than 549 species of leeches are reported from the world (Bondyopadhyay, P. K. and MandaI, C.K. 2006) of which about 63 species have so far been recored in Indian region.In West Bengal, however 28 species are now known to occur in varied ecological conditions from plains to the mountains, low to heavy rainfall areas and from river bed to ponds.Some species live permanently in water while others in dampy bushes under rotten leaves, bricks and stones.
Leeches never destroy agriculture crops, fruits and vegetations and only subsist on blood of various animals.Sometimes they take small insect larvae.
The present study is based on the material collected by the author from different districts of West Bengal during 1990Bengal during -2003. .The material is represented by 28 species belonging to 13 genera under 4 families.Of these, 3 species are new in the world and 7 forms have new locality record, MandaI (2004MandaI ( -2006)).Harding and Moore (1927) provided a comprehensive account of the Indian leeches.The other workers like Baugh (1960) and Sanjeeva Raj and Gladstone (1981) contributed their mights to the taxonomy of this group.

MATERIAL AND METHODS
The hulk of the n1aterials dealt with the present materials were collected by me during 15 years (1990-20CJ5) taking personal endeavour in West Bengal.All the material so collected has been deposited in the National Zoological Collection (N.Z.e. ) of India at the Zoological Survey of India, Calcutta.The rest of the materials including the "types" have been selected from the extensive collection present at the N.Z.C. of India.Collections were made from all districts of West Bengal.
Hilly area, dry area, river, ponds, lakes, marshy land, plain land, national park, tiger reserve, were the target collection spot.
The field observations and collections were made during all the seasons of year.In course of survey almost all niches are taken into consideration to find out the leech individuals occurring in the habitat/ecosystem.A sampler is used to collect the specimens.A net hangs from a quadrangular body, Inade of still.Each arms of the structure is 30 cm. and a handle of steel is attached in the Iniddle of one arm of the quadrangular structure.In the case of free-living species five sites froIn a selected ecosystell1 (water body) are taken into consideration to note the number of leeches occurring in the system.From each site/station an area of 30cm.square, has been selected at randoll1 and the nUll1ber of leeches occurring there, are counted.The mean of such five readings are considered for actual population density per 30 cm. square, which will be computed into no/ In 2 .In case of parasitic and malacophagous leeches, attempts have been made to note the number of leeches attached with the host body.In such case five or more host individuals are taken into account at random and mean would be considered for population density of this external parasite per host.The malacophagous leeches are counted on the basis of samplings of pelagic molluscs fr0I11 an area of 30 CIn. square from the concerned water body.Also in this case five such samplings are taken and the leeches attached/infested with snails are counted and mean of the five readings have been considered for the final data.In course of such studies, soil and water samples were collected to study some of the in1portant factors of the environment.The climatic factors have also been recorded from the Ineteorological stations at district headquarters.The pH of water samples was recorded with the help of pH indicator instrument.Breeding seasons of leeches are determined on the basis of observation of the egg, young and mating activities.The leeches are narcotized and preserved following the method recorded in the book entitled, "Hand Book for Zoological Collectors" published by the Director, Zoological Survey of India, Calcutta (1985).
The saInples were preserved in 700/0 alcohol after necessary narcotization.Preserved samples were sorted very carefully using binocular.Immediately after collection, the material was washed in pond water or in any fresh water and allowed to relax in water mixed with drops of 70% alcohol for about 2 hours to avoid twisting or breaking.For the good dissection, specimens are kept in 4% forn1alin for 24 hours and then transferred to 700/0 alcohol after proper washing in fresh water for preservation.It is necessary to dissect and examine the caeca, epididymis, and vaginal duct of the speciInens for taxonolnic study.VI.Six pairs of sublobate lateral caeca.

I.
Three pairs of eyes lies in rings 5, 7 and 8.
III.The first and smallest paIr of eyes closely approximated.

I.
Two pairs of eyes in ring 4 and 5.
II. Caudal sucker small.III.Three longitudinal rows of sensory papillae (one median and two intermedians).

I.
Colour dull green but usually white in preserved state.
II. Dorsal surface wi th fi ve brown Longi tudi nal stripes.
III. Papillae two pairs on dorsal side.
IV Eyes one pair on ring 4.
V Crop with six pairs of simple lateral caeca.

I.
Flattened translucent body is richly pigmented.
II.Seven longitudinal rows of lemon-yellow spots on dorsal surface.
III. Two pairs of eyes are on ring three and four.
IV Male and female pore opens between ring 29 and 30.

I.
Eyes two pairs on rings 3 and 4 but anterior pair very minute.III.18 greenish brown sub parallel longitudinal lines on the dorsal side 6 mid ventral.
IV A bulb shaped structure on the dorsoventral part of the anterior portion of the body.
Larger forms attain a length of 13 mm.
III. Three pairs of papillae on dorsal surface.
II. Head region dilated and distinct from rest of the body.III.Transverse stripes broken, pale yellow in colour found on the dorsal surface.I. Three pairs of eyes are disposed in two sub-parallel rows in rings 3, 4 and 7. II.Ovate-acuminate body.III.Roughened dorsal surface due to numerous small papillae closely set on every ring.Paraclepsis gardensi MandaI, 2004 I. Eyes three pairs (2 nd pair largest).II.Stomach with seven pairs of caeca (Branched and leafy).
II. Papillae small, closely set on dorsal surface.III.Eyes one pair, closely placed.IV Male and female pores open between rings 24/25 and 26/27 respectively.II.crown brown, with black stripe.III.Median head tessellae prescnt.IV Dorsal intermediate papillae prominent.