Are crocodiles really monophyletic? Evidence for subdivisions from sequence and morphological data

摘要

Recently, the phylogenetic placement of the African slender snouted crocodile, Crocodylus cataphractus, has come under scrutiny and herein we address this issue using molecular and morphological techniques. Although it is often recognized as being a "basal" form, morphological studies have traditionally placed C cataphractus within the genus Crocodylus, while molecular studies have suggested that C. cataphractus is very distinct from other Crocodylus. To address the relationship of this species to its congeners we have sequenced portions of two nuclear genes (C-mos 302 bp and ODC 294 bp), and two mitochondrial genes (ND6-tRNA(glu)-cytB 347 bp and control region 457 bp). Analyses of these molecular datasets, both as individual gene sequences and as concatenated sequences, support the hypothesis that C cataphractus is not a member of Crocodylus or Osteolaemus. Examination of 165 morphological characters supports and strengthens our resurrection of an historic genus, Mecistops (Gray 1844) for cataphractus. (c) 2006 Elsevier Inc. All rights reserved.