Abstract
This study records, for the first time, the occurrence of all four male morphotypes in a population of Macrobrachium amazonicum from a continental environment, with an entirely freshwater life cycle. The specimens studied came from the Tietê River, state of São Paulo, Brazil, and were collected in a lotic environment downstream from Ibitinga Dam. This population was compared with other continental populations, including a population from the dam itself, collected in a previous study. Four samples of 30 minutes were taken monthly, using a trap, from January to April 2011. Each male specimen was measured with respect to seven body dimensions as follows: carapace length (CL), right cheliped length (RCL), dactyl length (DCL), propodus length (PPL), carpus length (CRL), merus length (ML) and ischium length (IL). The relative growth was analyzed based on the change in growth patterns of certain body parts in relation to the independent variable CL. The four male morphotypes proposed for the species were found using morphological and morphometric analyses. Different biological characteristics were found between the populations studied. The male population of the lake of Ibitinga and from Pantanal presented mean sizes and number of morphotypes lower than the population studied here. These differences seem to be closely related to ecological characteristics of the environments inhabited by these populations. Our results supported the hypothesis that coastal and continental populations of M. amazonicum belong to the same species.
Highlights
The Amazon River Prawn Macrobrachium amazonicum (Heller 1862) is endemic to South America, where the species extends from Venezuela to Argentina
Differences in reproductive systems indicate that long vicariant separation has allowed for diversification in different catchment areas, suggesting that M. amazonicum is a complex of closely related but separate species
The four distinguishable male morphotypes identified by Moraes-Riodades & Valenti (2004) are as follows: Translucent Claw (TC), Cinnamon Claw (CC), Green Claw 1 (GC1), and Green Claw 2 (GC2)
Summary
The Amazon River Prawn Macrobrachium amazonicum (Heller 1862) is endemic to South America, where the species extends from Venezuela to Argentina. According to Odinetz-Collart (1988) and OdinetzCollart and Moreira (1993), prawns caught in flowing water of large rivers grew to larger sizes than did prawns collected in the lentic water of lakes and reservoirs that can reach sexual maturity at smaller sizes In this species, sexually mature males can have different morphotypes, which have different sizes, morphology, physiology and behavior. The four distinguishable male morphotypes identified by Moraes-Riodades & Valenti (2004) are as follows: Translucent Claw (TC), Cinnamon Claw (CC), Green Claw 1 (GC1), and Green Claw 2 (GC2) These morphotypes differ in cheliped morphology and in certain morphometric relationships. Here we compare the sizes and male morphotypes of M. amazonicum among the population of the flowing waters downstream the Ibitinga Dam, in the Tietê River, state of São Paulo, Brazil, the population studied before by Pantaleão et al (2012) of the lentic waters upstream from the reservoir and a population of the same hydrographic basin at Pantanal region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
