The paper reports on the statistical analysis of growth pattern and meristic studies of body parts of the spotted estuarine prawn, Macrobrachium equidens (Dana) of Vembanad Lake, Kerala State. The results showed that the growth pattern of carapace length, telson length, ischium length and dactylus length in relation to total length were significantly different between the sexes at slope itself (at 1% level) and growth pattern of abdominal length, merus length, carpus length, propodus length and palm length were significant at elevations (5%, 1% levels). The average sizes of all these characters were greater in males than in females. Regression equations have been calculated for the characters and presented in the text. Among the characters of the carapace, rostrum length, post-orbital length showed significant difference between sexes at 1% level (slope value) and width of carapace at 1% level (elevations). The average sizes of all these characters were higher in males. Among the meristic characters studied, the species exhibited sexual dimorphism with regard to dorsal teeth, post-orbital teeth and ventral teeth. The fundamental data generated is essential for establishing the species status as well as it is useful for making comparison with other species

Jayachandran, K.V.

Sebastian, A.

Aquatic Commons

J. Indian Fish. Assoc., 37: 1-6, 2010 1 
MOR.PHOMETRIC AND MER.ISTIC STUDIES OF THE SPOTTED ESTUARINE PRAWN, 
MACROBRACHIUM EQUIDENS (DANA) OF VEMBANAD LAKE, KER.ALA STATE 
Jayachandran, K. V1 • And Anitta Sebastian 
College of Fisheries; Kera/a Agricultural Universit~ 
Panangad P. O.; Cochin 682 506, Kera/a State 
1corresponding author: e-mail: chandrankvj@gmail.com 
ABSTRACT 
The paper reports on the statistical analysis of growth pattern and meristic studies of 
body parts of the spotted estuarine prawn, Macrobrachium equidens (Dana) of Vembanad Lake, 
Kerala State. The results showed that the growth pattern of carapace length, telson length, 
ischium length and dactyl us length in relation to total length were significantly different between 
the sexes at slope itself (at 1% level) and growth pattern of abdominal length, merus length, carpus 
length, propodus length and palm length were significant at elevations (5%, 1% levels). The 
average sizes of all these characters were greater in males than in females. Regression equations 
have been calculated for the characters and presented in the text. Among the characters of the 
carapace, rostrum length, post-orbital length showed significant difference between sexes at 1 % 
level (slope value) and width of carapace at 1% level (elevations) . The average sizes of all these 
characters were higher in males. Among the meristic characters studied, the species exhibited 
sexual dimorphism with regard .to dorsal teeth, post-orbital teeth and ventral teeth. The 
fundamental data generated is essential for establishing the species status as well as it is useful for 
making comparison with other species. 
Key words: Growth pattern, Meristic studies, Macrobrachium equidens. 
INTRODUCTION 
Taxonomic studies in crustaceans are 
largely based on the morphological as well as 
proportions of different body parts. It is 
species specific also. However, in crustaceans 
allometric studies on different body parts are 
seldom being made. Such studies will help in 
establishing the sexual dimorphism also 
(Farmer, 1986; Jayachandran and Joseph, 
1985, 1988; Jayachandran et al., 1996; Koshy, 
1969, 1971; Mathews, 1992; Sriraman et al.; 
1987). Macrobrachium equidens (Dana) 
exhibits close relationship with M. sulcatus 
(Henderson and Matthai, 1910), because of 
this reason, the two names were synonomised 
(Holthuis, 1950). A recent study revealed that 
these two species are distinct (Jayachandran, 
2001). In order to establish the species status 
of M. equidens, morphometric and meristic 
studies have been attempted and the present 
paper is a report on the same. 
MATERIAL AND METHODS 
A total of 143 specimens of M. 
equidens (73 males, ranging in total length 
from 51 to 97 mm and 70 females, ranging in 
total length from 49 to 81 mm) were collected 
from the Vembanad lake, Cochin, Kerala 
State. The characters studied are total length 
(length from the tip of rostrum to tip of tel son, 
Tl), carapace length (from tip of rostrum to 
2 Jayachandran, K. V. And Anitta Sebastian 
postero-dorsal limit of carapace, Cl), post-
orbitai length (from the level of orbit to 
postero-dorsal limit of carapace, Pol), 
abdomen length (from antero-dorsal part of 
abdomen to antero-dorsal limit of telson, 
Abl), telson length (from antero-dorsal part of 
telson to tip of telson, LT), body length (from 
the level of orbit to antero-dorsal limit of 
telson, Bl), rostrum length (from the level of 
orbit to tip of rostrum, Rl), width of carapace 
(maximum width of carapace, WC), second 
pereopods: ischium length (from the tip of 
basis to tip of ischium, LI), merus length (from 
the tip of ischium to tip of merus, LM), carpus 
length {from the tip of merus to tip of carpus, 
LC), propodus length (from the tip of carpus to 
tip of fingers, LP), palm length (from the tip of 
carpus to the base of movable finger, LPa), 
dactylus length (from the base of movable 
finger to its tip, LD). lengths were accurately 
measured to the nearest mm. In the present 
study, the characters namely Cl, Bl, Abl, LT, LI, 
LM, LC, LP, LPa, LD were related to Tl and Pol, 
Rl, WC were related to CL The data were 
subjected to statistical analysis by adopting 
the method of analysis of covariance 
(Snedecor and Cochran, 1975). The meristic 
characters studied included range of rostral 
teeth on both the dorsal (post-orbital and 
rostral) and ventral margins. From the data, 
the range of teeth and percentage frequency 
distribution of teeth have been calculated. 
Chi-square test also has been applied to find 
out whether any significant difference exists in 
these characters between the sexes. 
RESULTS AND DISCUSSION 
Characters related to total length 
The results are given in Table 1. The 
results showed that the growth pattern of Cl, 
LT, LI, and LD were significantly different 
between the sexes at slope itself (at 1% level). 
Growth pattern of LM, LC, LP and LPa were 
significant at 5% level whereas that of 
abdomen length significant at 5% level 
(elevations). However, growth pattern of 
body length was not significantly different. 
Average sizes of body measurements were 
also worked out and presented in Table 1. It 
can be seen that the average sizes of all these 
characters were greater in males than in 
females. Regression equations have been 
calculated for the characters and presented in 
the table. 
Table 1: Comparison of regression equations (males and females) of M. equidens 
Characters (Y} Regression equation Comparison of Mean 
M-male F - female Y=(n = 73 M; 70 F) Slope Elevation values 
A. Growth in relation to total length (X} and 
Carapace length -M 0.47064 x - 0.3606 9.709* 3.181 ** 34.480 
- F 0.4592 x -1.05879 27.586 
Abdomen length -M 0.3847 x - 0.6174 2.839 4.021 ** 29.096 
- F 0.40607 x + 0.4344 25.764 
Teison length -M 0.11393 x + 1.8813 18.597* 0.293 10.315 
- F 0.1248 x + 0.7078 08.493 
-, 
MORPHOMETRIC AND MERISTIC STUDIES OF THE SPOTIED ESTUARINE PRAWN, MACROBRACHIUM 3 
EQUIDENS (DANA) OF VEMBANAD LAKE, KERAlA STATE 
Body length -M 0.23299 x + 30.9251 0.085 0.417 48.173 
- F 0.60704 x + 4.6126 42.479 
lschium length M 0.20554 x - 3.4899 17.089* 3.726** 11.726 
- F 0.14474 x -0.62848 08.400 
Merus length -M 0.37492 x -11.5214 1.770 64.977* 16.233 
- F 0.19132 X-2.4126 09.521 
Carpus length -M 0.69299 X-24.9990 0.713 64.182* 26.301 
- F 0.31063 x -5.7910 13.586 
Propodus length -M 0. 7871 x - 27.5646 1.077 56.230* 30.699 
- F 0.38575 x - 6.8695 17.193 
Palm length -M 0.55718 x -22.0139 0.663 46.585* 19.233 
- F 0.24554 x - 4.93048 10.386 
Dactylus length -M 0.23506 X-5.27724 7.650* 59.453* 12.123 
- F 0.24554 x - 4.93048 10.386 
Dactylus length -M 0.23506 X-5.27724 7.650* 59.453* 12.123 
- F 0.14188 X-1.7073 07.143 
B. Growth in relation to carapace length (X) and 
Rostrum length - M 0.27969 x + 6.2783 19.423* 02.972 15.747 
- F 0.38897 x + 1.3273 12.057 
Post - orbital length - M 0.5774 X-0.65331 25.13 * 18.190* 18.893 
- F 0.5672 x + 0.62543 16.271 
Carapace width -M 0.4180 x -1.13076 0.016 6.655* 13.020 
- F 0.37895 x + 0.66795 11.121 
{* p < 0.01; ** p < 0.05) 
4 Jayachandran, K. V. And Anitta Sebastian 
Characters related to carapace length 
Among the characters of the 
carapace, post-orbital length and rostrum 
length showed significant difference between 
sexes, at 1 % level (slope value) (Table 1) 
whereas WC at 5% level (elevations). The 
average sizes of all these characters were 
higher in males. Regression equations for 
these characters are available in the table. 
Meristic characters 
The range of dorsal rostral teeth in 
males was 9-12 and that of females 8-12. The 
range of post-orbital teeth was 3-4 and ventrar 
teeth was 4-6 in both sexes. Percentage 
frequency distribution of teeth: in males most 
frequent number of dorsal teeth was 10, 
followed by 11 and 9. In females the 
frequency was 10, 9, and 7. Regarding the 
post-orbital teeth, maximum percentage 
occurrence was 3 in both the sexes of this 
species. In the case of ventral teeth, the 
maximum frequency was 5 in both the sexes 
followed by 4 in males, 6 in females. 
Table 2: Range, percentage frequency distribution of teeth on the dorsal and ventral rostrum 
and chi-square test value of meristic characters of M. equidens 
Characters Male Female Observed 
Chi-square 
No. of specimens analyzed 70 70 
Range of teeth 
Dorsal 9-12 8-12 
Post-orbital 3-4 3-4 
Ventral 4-6 4-6 
Percentage freguency distribution 
Dorsal teeth 11.409 (P <0.05} 
9 9.7 17.4 
10 51.4 68.1 
11 34.7 11.6 
12 4.2 2.9 
Post orbital teeth 8.104 (P <0.05) 
3 80.0 95.7 
4 20.0 4.3 
Ventral teeth 6.268 (P <0.05) 
4 20.0 5.7 
5 63.4 77.1 
6 16.9 17.1 
MORPHOMETRIC AND MERISTIC STUDIES OF JttE SPOTIED ESTUARINE PRAWN, MACROBRACHIUM 5 
EQUIDENS (DANA) OF VEMBANAD LAKE, KERALA STATE 
Chi-square test 
It is interesting to note that the 
pattern of distribution of teeth showed sexual 
dimorphism with regard to all the characters 
studied (P <0.05). It has been reported that M. 
rosebergii of Hooghly estuary was sexually 
dimorphic (Bhimachar, 1965; Rajyalakshmi, 
1980). The growth pattern of CL in relation to 
TL in the two sexes of this species was 
significantly distinct in the species (Raman, 
1967; Rao, 1967). Similarly, M. malcolmsonii 
of Godavari and Hooghly river systems 
showed significant relationship between TL 
and CL. CL and LT in relation to TL in M. 
scabriculum and M. idella and also RL in 
relation to CL in M. scabriculum showed 
significant difference in the growth pattern 
between sexes (Jayachandran and Joseph, 
1985; 1988). WC in relation to CL in M. idella 
was also significantly different. In M. lamarrei 
the growth rate is higher in females than in 
males {Koshy, 1969). In M. idella the growth 
rates of CL and LT in relation to TL were greater 
in males whereas that of WC in relation to CL 
was greater in females (Jayachandran and 
Joseph, 1988). In M. scabriculum the growth 
rate was higher in males in all the characters 
studied (Jayachandran and Joseph, 1985). In 
this species, the average size of all the 
characters were greater in males than in 
females. In many species of Macrobrachium/ 
the males grow larger than females. Thus M. 
rosenbergii/ M. malcolmsonii/ M. idella, M. 
gangeticum, M. vilfosimanus, M. scabriculum 
come under this category (Jayachandran, 
2001). In variance with this, the average 
length and WC, RL and LT of M. idella are 
reported to be higher in females than in males 
(Jayachandran and Joseph, 1985; 1988). 
Detailed morphometric relationship of 
various body parameters of commercially 
important penaeid prawns have been worked 
out (Farmer, 1986; Mathew, 1992; Sriraman et 
al., 1987). The fundamental data generated at 
present for the species will be highly essential 
forthe establishment of the species status and 
for making comparison with related species. 
ACKNOWLEDGEMENTS 
The authors are thankful to the Dean, 
College of Fisheries for the facilities provided 
and to Mr. Mathew Sebastian, Asst. Professor 
(Statistics), College of Fisheries, Panangad, 
Kechi (Kerala) for helping in the statistical 
interpretation. 
REFERENCES 
Bhimachar, B. S., 1965. Life history and 
behaviour of Indian prawns. Fish. Tech., 
2(1):1-11. 
Farmer, A. S. D., 1986. Morphometric 
relationships of commercially important 
species of penaeid shrimp from Arabian 
Gulf; Kuwait Bull. Mar. Sci., 71-21. 
Holthuis, l. B., 1950. Subfamily 
Palaemoninae. The Palaemonidae 
collected by the Siboga and sne!lius 
expeditions with remarks on other 
species. I. The Decapoda of the Siboga 
Expedition, Part X. Siboga Exped., mon./ 
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Jayachandran, K. V., 2001. Palaemonid 
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Jayachandran, K. V. and Joseph, N. I., 1985. 
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Morphometric and meristic studies of the spotted estuarine prawn, Macrobrachium equidens (Dana) of Vembanad Lake, Kerala State

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Morphometric and meristic studies of the spotted estuarine prawn, Macrobrachium equidens (Dana) of Vembanad Lake, Kerala State

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