Biomorphology of crustaceans in a unpolluted stream in the equatorial forest of Cameroon
The study focuses on the biomorphology of crustaceans of the Matourou stream at Nkoukoum in the Central region of Cameroon. Two species of shrimp (Caridina sp. and Macrobrachium sp.) and three morphotypes of the Soudanonautes crab were harvested, identified and characterized. Caridina sp. of small size (10-30 mm) is characterized by a dorso-ventrally spinous rostrum. Macrobrachium sp. measures between 26 and 100 mm. As for the morphotypes of crab of genus Sudanonautes, type I is greenish-yellow, with a frontal ridge slightly curved backwards and widely interrupted in the middle. It carries a very poorly developed epibranchial tooth. Type II has developed pointed ex-orbital and intermediate teeth. Type III, on the other hand, has an epibranchial tooth that is half as large as the first two. The allometric coefficients b are 2.50, 2.38 and 2.60 respectively for Caridina sp., Macrobrachium sp. and Sudanonautes spp.; they indicate negative allometric growth for these three species that coexist in this ecosystem characterized by fresh, neutral and well-oxygenated waters. The average values of the condition factor K and the allometric coefficient b obtained for the most abundant species (Caridina sp. and Sudanonautes spp.) show that the hydroecological variables of the Matourou stream are favorable for their survival in the forested area of Nkoukoum.