A NOTE ON THE FIRST REPORT OF MACROBRACHIUM JOSEPHI JAY ACHANDRAN, 2001 OUT OF THE TYPE LOCALITY

While examining the freshwater prawns deposited in the Southern Regional Station of the Zoological Survey of India, the authors have came across Macrobrachium josephi Jayachandrana, 2001 (Plate-l), which is known to occur only in Kerala. From earlier reports it is known that nearly 10 species of the freshwater prawns of the genus Macrobrachium are available in Tamil Nadu (Raghunath an and Valarmathi, 2005). The species reported are Macrobrachium aemulum (Nobili), Macrobrachium australe (Guerin-Meneville, 1838), Macrobrachium canarae (Tiwari, 1958), Macrobrachium lamarrei lamarrei (H. Milne Edward, 1952), Macrobrachium malcolmsonii (Milne Edward, 1837), Macrobrachium nobilii (Henderson and Matthai, 1910), Macrobrachium rosenbergii (de Man, 1879), Macrobrachium rude (Heller, 1862), Macrobrachium scabriculum (Heller, 1862), Macrobrachium indicum Jaychandran et Joseph, 1986. The present study yields one more species of Macrobrachium to Tamil Nadu.


DIAGNOSTIC CHARACTERS
Rostrum with slight basal crest raised above the orbit and is longer than the antennular peduncle but falls short of the antennal scale.The upper margin of the rostrum is provided with 10 to 13 teeth of which 2 or 3 are located on the carapace, and the lower margin of the rostrum posses 5-6 teeth.The structure and the arrangement of spines on the rostrum are similar to Macrbrachium malcolmsonii.The length of the rostrum is shorter than the carapace (rostrum 0.57 to 0.6 times of the Carapace).In larger adult males the carapace is scabrous due to the presence of minute prickles.But in females and smaller males the carapace is smooth.Sexual dimorphism is observed based on the II cheliped.In male the second cheliped is very strong and well developed with thick tubercles but in females it is short, slender and smooth.The second cheliped in larger adult males are longer than the total body length (cheliped 1.63 to 1.66 times of the total body length).The fingers are dissimilar, the movable finger is slightly shorter than the immovable finger and is covered with dense pubescence except in the tip, but the immovable finger lacks such pubescence.Both the fingers are slightly curved at the tip and they oppose each other when closed.Both the fingers have two small tubercles which fix when the fingers are closed.Fingers are distinctly shorter than palm (Fingers 0.45 to 0.72 times of the palm).Carpus longer than the finger, palm, merus and ischium but shorter than the chela and the combined length of the merus and ischium.Merus shorter than the palm and carpus but longer than the finger and ischium.
Appendix masculina of the male II pleopod reaches half of the endopod and provided with setae on its entire length.

MACROBRACHIUM MALCOLMSONII :
The following table shows the difference between the Macrobrachium josephi and Macrobrachium malcolmsonii.
2. Carapace of the adult males scabrous 2. Carapace of the adult males smooth.
due to the presence of minute prickles.

REMARKS
Earlier Macrobrachium josephi was described by Jayachandran (2001) from Kerala and the maximum size of the species recorded by him is 185 mm.In his account on the Biodiversity, Taxonomy, Biology and Management of Palaemonid prawns Jayachnadran (2001) has differentiated Macrobrachium josephi from other larger species like Macrobrachium birmanicum and Macrobrachium malcolmsonii.For the first time Macrobrachium josephi is recorded outside Kerala from Tamil Nadu.Also it is worthy to mention that the maximum size recorded during the present study is 193 mm.this will form the largest specimen of the species so for reported.

Finger
3. II Cheliped of the adult male.3.II Cheliped of the adult male.a)Total length of the II cheliped is 1.63-a)Total length of the II cheliped is 0.75-1.66times of the total body length.1.09 times of the total body length. of the various proportion of the g) Length of the various proportion of the II cheliped of 184.5 mm male.II cheliped of 184.5 mm male.the cheliped = 300.8mm Total length of the cheliped = 208mmh) The average % of various proportion of h) The average % of various proportion male second cheliped.of male second cheliped.