Morphometric variability in populations of Palaemonetes spp. (Crustacea, Decapoda, Palaemonidae) from the Peruvian and Brazilian Amazon Basin

Abstract

ABSTRACT. Morphometric variability among shrimp populations of the genus Palaemonetes Heller, 1869 from seven lakes (Huanayo and Urcococha, in Peru; Amanã, Mamirauá, Camaleão, Cristalino e Iruçanga, in Brasil) in the Amazon Basin, presumably belonging to Palaemonetes carteri Gordon, 1935 and Palaemonetes ivonicus Holthuis, 1950, were studied. The morphometric studies were carried out from the ratios obtained from the morphometric characters. Multivariated analysis (Principal Components Analysis-PCA, Discriminant Function Analysis and Cluster Analysis) were applied over the ratios. Intra-and interpopulation variations of the rostrum teeth, and the number of spines in the male appendix, were analyzed through descriptive statistics and bivariate analysis (Spearman Rank Correlation test). Results indicated a wide plasticity and overlapping in the studied ratios between populations. The Principal Components Analysis was not able to separate different populations, revealing a large intrapopulation plasticity and strong interpopulation similarity in the studied ratios. Although the Discriminant Functions Analysis was not able to fully discriminate populations, they could be allocated in three subgroups: 1) Cristalino and Iruçanga; 2) Huanayo, Urcococha and Camaleão and 3) Mamirauá and Amanã. The first two groups were morphometrically separated from each other, whereas the third one presented a strong overlap with the former two. The Cluster Analysis confirmed the first two subgroups separation, and indicated that the first and third groups were closely related. Rostrum teeth and number of spines in the appendix masculina showed a large intrapopulation variation and a strong overlapping among the studied populations, regardless of the species.KEYWORDS. Palaemonetes, morphometry, Amazon Basin, sibling species, freshwater shrimp. Holthuis, 1950. Os estudos morfométricos foram realizados a partir das razões obtidas dos caracteres morfométricos. Análise multivariada (análise de componentes principais, análise de função discriminante e análise de agrupamento hierárquico) foram aplicadas unicamente sobre as razões. Variações intra-e interpopulacionais do número de dentes de rostro, assim como do número de espinhos no apêndice masculino, foram analisadas mediante estatística descritiva e análise bivariada (teste de Spearman). Os resultados indicaram uma grande plasticidade e sobreposição nos caracteres diagnósticos entre as populações. A análise de componentes principais não conseguiu separar as diferentes populações, revelando uma grande plasticidade intrapopulacional e forte semelhança interpopulacional nas razões estudadas. Embora a análise de funções discriminantes não tenha logrado discriminar completamente as populações, estas ficaram alocadas em três subgrupos: 1) Cristalino e Iruçanga; 2) Huanayo, Urcococha e Camaleão e 3) Mamirauá e Amanã. Os primeiros dois grupos ficaram morfologicamente separados entre si, enquanto que o terceiro apresentou uma forte sobreposição com os dois anteriores. A análise de agrupamento hie...

Morphological differentiation among species of the genus Mugil Linnaeus, 1758 (Mugilidae) from Côte d’Ivoire

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