Evolutionary History of Some Plagiorchioid Trematodes of Anurans

Abstract

Brooks, D. R. (Gulf Coast Research Laboratory, P.O. Box A.G., Ocean Springs, MS 39564) 1977. Evolutionary history of some plagiorchioid trematodes of anurans. Syst. Zool. 26:277-289.-Cladistic interrelationships of plagiorchioid genera found in anuran intestines and of species of the genus Glypthelmins are analyzed to determine pattems of dispersal and vicariance. The first analysis reveals three generic lineages, each characterized by one genus whose species are distributed on four or more continents or subcontinents in addition to related genera restricted in number of species and found on a single continent or two adjacent continents. Examination of the distribution of the three characteristic genera, Mesocoelium, Opisthioglyphe, and Glypthelmins, suggests similar but not congruent dispersal-tracks and shows different centers of form-making for each. In the second analysis, cladistic (genealogical) relationships of species of Glypthelmins in the Old World and of species in Central and North America can be accounted for on the basis of vicariance from widely-distributed ancestral taxa. Vicariance of the South American species corresponds with the phylogeny of their hosts as proposed by Lynch (1973). This, the first study using cladistical methodology for deducing the evolutionary history of a group of parasitic helminths, demonstrates the feasibility and applicability of that methodology. [Evolutionary history; cladistics; biogeography; vicariance; continental drift; coevolution; anuran parasites; plagiorchioid digeneans.]