The morphological variation of the endangered catfish Rita rita was studied based on meristic, length–weight relationship (LWR), traditional (TRA) and truss (TRU) distance based morphometric analysis of 200 juveniles collected from the Old Brahmaputra, Jamuna, Meghna and Kangsa rivers. Data were subjected to Kruskal–Wallis test for meristic counts, t test for LWR, univariate ANOVA, multivariate discriminant function analysis and canonical analysis (CA) both for TRA and TRU morphometric characters to discriminate the populations. Kruskal–Wallis test denoted that only one (caudal fin rays) out of six meristic counts was significantly (p < .05) variable among the stocks. One sample t test clarified that all parameters of LWR were significantly (p < .05) differentiated in all stocks. Univariate ANOVA revealed significant (p < .001, p < .01, and p < .05) differences among the four stocks in 14 of 15 standardized TRA traits and 17 of 25 TRU distances, respectively. The first discriminant function (DF1) explained 59.4% and 68.0% of total variance, while 30.6% and 23.1% by DF2, 10.0% and 8.9% by DF3 for TRA and TRU features, respectively among the stocks. CA showed a clear separation of the stocks both for TRA and TRU measurements. The overall random assignment of individuals into their original groups was high as 78.5% for TRA and 78.0% for TRU characters, respectively, indicating that all the four stocks are highly divergent from each other. The results exposed existence of four distinct phenotypic stocks of R. rita in the tested rivers.

中文翻译：

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濒危cat鱼Rita rita（汉密尔顿，1822年）的四个河流种群（孟加拉国）之间的形态变异

基于meristic，长度-重量关系（LWR），传统（TRA）和桁架（TRU）距离的形态分析，研究了濒危cat鱼Rita rita的形态变异，该形态分析来自于古雅鲁藏布江，贾木纳，梅格纳和康萨等地收集的200种幼体河流。对数据进行Kruskal-Wallis检验以进行总体计数，t检验用于LWR，单变量ANOVA，多元判别函数分析以及TRA和TRU形态计量特征的正则分析（CA），以区分总体。Kruskal–Wallis检验表明，在六种优势计数中，只有一种（尾鳍射线） 在这些种群之间具有显着的变化（p <.05）。一个样本t测试表明 ，所有股票中LWR的所有参数均存在显着差异（p <.05）。单变量方差分析显示显着性（p  <.001，p  <.01和p <.05）分别在15个标准TRA性状中的14个和25个TRU距离中的17个中的四个种群之间的差异。第一个判别函数（DF1）解释了股票的TRA和TRU特征，分别解释了总方差的59.4％和68.0％，而DF2分别解释了30.6％和23.1％，DF3解释了10.0％和8.9％。CA对TRA和TRU的测量均显示出库存的明显分离。个体对原始群体的总体随机分配分别高达TRA的78.5％和TRU字符的78.0％，这表明所有四只股票彼此之间都存在很大差异。结果暴露了在测试河流中存在四种不同的R. rita表型种群。