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Two new tetraphyllidean cestodes are described from the freshwater stingray Potamotrygon magdalenae from Colombia. The new genus Potamotrygonocestus is proposed for P. magdalenensis, which differs from Pedibothrium by having a bilobed rather than X-shaped ovary, and simple rather than bifid hooks. It further differs from Pachybothrium hutsoni by having bothridial hooks inserted immediately posterior to an accessory sucker rather than inserted in the middle of a thick muscular pad. Potamotrygonocestus magdalenensis is unique among known tetraphyllideans by possessing vitellaria which are compact, cylindrical bands in the lateral portions of the middle of the proglottid. The second new species, Rhinebothrium moralarai, resembles R. scorzai by having its genital pore and terminal genitalia at the ovarian level, greatly reduced poral ovarian lobes, and by parasitizing a freshwater stingray. It differs from R. scorzai in number of bothridial loculi, testes per proglottid, and proglottids per strobila; by having quadrate rather than canoe-shaped bothridia; and by parasitizing Potamotrygon magdalenae rather than P. hystrix.

Loggerhead sea turtles (Caretta caretta) from the Atlantic seaboard (Florida to Massachusetts) were examined at the Marine Pathology Laboratory, University of Rhode Island, from March through December, 1980. Three genera of blood flukes (spirorchids) were found in 14 (33%) of the 43 turtles. Gross signs in heavily infected animals included cachexia, anemia and enteritis. Histopathological lesions were similar to those present in homeotherms with schistosomiasis. Granulomatous gastritis, enteritis, hepatitis, pneumonitis, and nephritis were present. Acute and chronic vasculitis accompanied metastasis of eggs. Infected animals had severe hepatic hemosiderosis, indicative of the anemia observed grossly. Evidence is presented that spirorchidiasis is prevelent in sub-adult loggerhead sea turtles, is responsible for extensive lesions and may be responsible for significant debilitation and mortality.

The unified theory of evolution is an expansion of Darwinian theory that asserts that evolution is driven by entropic accumulation of genetic information that is constrained and organized primarily by the genealogical effects of phylogenetic history and developmental integration, and secondarily by ecological effects, or natural selection in its classical mode. Phylogenetic systematic analysis of the 8 major groups of parasitic rhabdocoelous platyhelminths permits empirical macroevolutionary evaluation of these postulates. Of the 131 characters considered, 127 are phylogenetically constrained, and 4 show evidence of 1 case of convergence each. Data from different developmental stages are phylogenetically congruent, despite differences in ecology among those stages. Ecological diversification, indicated by phylogenetic association of definitive hosts and parasites, and by changes in ecological components of life cycle patterns, is more conservative evolutionarily than diversification in developmental patterns, indicated by the appearance of unique larval stages, asexual proliferation of larvae, polyembryony, and heterochronic changes. These observations support the macroevolutionary postulates of the unified theory.

A juvenile Macacca mulatta that died following a peracute illness was found to be harboring about 25 mature Choanotaenia infundibulum tapeworms. These cestodes commonly infest birds, occasionally insectivores and rodents but have never been reported in nonhuman primates.

Explicit estimates of protist phylogeny should play a key role in the development of macroevolutionary theory. Nearly half the evolutionary history of living systems involved only protists, and many trends and traits of macroevolutionary significance originated in protist groups. Special areas of research that can make use of protist phylogenies include: (1) origin of life studies, (2) biotic aspects of the evolution of the environment, (3) developmental biology and evolution, and (4) macroevolutionary trends in the diversification of life.

Phylogenetic systematics is a relatively new formal technique that increases the precision with which one can make direct estimates of the history of phylogenetic descent. These estimates are made in the form of phylogenetic trees, or cladograms. Cladograms may be converted directly into classifications or they may be used to test various hypotheses about the evolutionary process. More than 20 phylogenetic analyses of helminth groups have been published already, and these have been used to investigate evolutionary questions in developmental biology, biogeography, speciation, coevolution, and evolutionary ecology.

A model of evolution which combines mutations and speciation mechanisms is presented and analyzed. Information and entropy of the populations generated by the model are calculated and followed through history. It is found that the model allows simultaneous increase of information and entropy with time, consistent with notions of physical entropy increase as well as biological evolution.