Morphological analysis of three Inia (Cetacea : Iniidae) populations from Colombia and Bolivia

摘要

We present new morphological data on three Colombian and Bolivian Inia populations. Analysis of morphometric data strongly suggests that Inia are sexually dimorphic, with males smaller for several variables and more heterogeneous than females. Our morphological data supported that Colombian Amazon males had the greatest total body length as well as greatest fluke values (tip to tip) compared to the males from the Orinoco and Bolivia Rivers. There were also significant differences in females among populations. The two Colombian groups (Amazon and Orinoco basin) presented greater total body length than the Bolivian array, while distance from jaw tip to tip of dorsal fin was greater in the Orinoco basin females than in the other two populations. A Canonic Population Analysis showed that the confidence intervals of the Colombian Amazon and Orinoco males were partially superposed. However, the Bolivian male sample was remarkably differing from these two populations. Two long standing debates exist in the systematic literature on Inia: (1) the number of extant species (one, Inia geoffrensis, or two I. geoffrensis and I. boliviensis) and (2) the number of extant subspecies of I. geoffrensis (I. geoffrensis geoffrensis, I. geoffrensis humboldtiana and I. geoffrensis boliviensis). Using recent collections of both molecular and morphometric data, we suggest the existence of two distinct species of Inia with no subspecific distinction among L geoffrensis populations.