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Abstract
The morphology of the egg and nymphal stages of Porocephalus stilesi and the eggs of Porocephalus clavatus were examined to determine if there are distinguishable characters that can be used to separate these two species and Porocephalus crotali.
Eggs of P. stilesi were taken from adult females collected from Lachesis muta, muta; eggs of P. clavatus were taken from females collected from Boa constrictor imperator. Both hosts were caught in Costa Rica.
Nymphal stages of P. stilesi were dissected out from adult male albino rats which had been fed eggs from the former collection.
The following structures of the egg and embryo of P. stilesi and P. clavatus were studied and measured: membranes, facette, dorsal organ, penetrating apparatus, oral armature, legs, and tail. these and P. crotali. Statistical comparisons were made between Some observations were also made on the activity of the embryo.
The morphology of the six nymphal stages of P. stilesi was studied. Data include measurements for body length, width, oral armature, hooks, body rings and number of segments and periods at which each nymphal stage was observed after the ingestion of eggs by the rats. A statistical comparison is made between the length and width of the body and of oral armature of P. crotali and P. stilesi.
The differences between measurements of the three possible combinations P. crotali-P. stilesi, P. crotali-P. clavatus and P. stilesi-P. clavatus were significant at the 5 % level for the following egg structures: external envelope (smaller diameter), outer shell (smaller diameter), length of body, length of tail, and transverse bar of the oral armature.
The differences between the measurements of P. crotali and P. stilesi nymphs were significant at the 5 % level for the body width of stages I and VI and for all body lengths of the six nymphal stages; for the length of the oral ring for all stages except for nymph VI; and for the width of the oral ring for all stages except V.
As all three species of Porocephalus carne from samples from different regions and hosts, it is very possible that the differences found are due to factors such as geographic distribution, hosts, plasticity of the embryo and nymph, age of eggs and nymphs, differences in techniques of fixation, variations in prepar ing and observing specimens, and to the samples from different females of Porocephalus.
Neither the statistical nor the morphological analyses have given good characters that can be used to separate these so-called species of Porocephatus satisfactorily.