Evolutionary History of Some Plagiorchioid Trematodes of Anurans

Abstract

Cladistic interrelationships of plagiorchioid genera found in anuran intestines and of species of the genus Glypthelmins were analyzed to determine patterns of dispersal and vicariance. The 1st analysis revealed 3 generic lineages, each characterized by 1 genus whose species are distributed on 4 or more continents or subcontinents and related genera restricted in number of species and found on a single continent or 2 adjacent continents. Examination of the distribution of the 3 characteristic genera, Mesocoelium, Opisthioglyphe and Glypthelmins, suggested similar but not congruent dispersal-tracks and showed different centers of form-making for each. In the 2nd analysis, cladistic (genealogical) relationships of species of Glypthelmins in the Old World and of species in Central and North America could be accounted for on the basis of vicariance from widely-distributed ancestral taxa. Vicariance of the South American species corresponded with the phylogeny of their hosts are proposed by Lynch (1973). This 1st study using cladistical methodology for deducing the evolutionary history of a group of parasitic helminths demonstrates the feasibility and applicability of that methodology.