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On a New Genus of the Family Branchiobdellidae (Oligochaeta)

1960; University of Notre Dame; Volume: 64; Issue: 1 Linguagem: Inglês

10.2307/2422899

1938-4238

Perry C. Holt,

Aquatic Invertebrate Ecology and Behavior

As a result of current work devoted to the systematics of the Branchiobdellidae, it has become increasingly obvious that a satisfactory treatment of the family awaits the completion of detailed anatomical studies of the genera which compose it. The erection herein of a new genus, which includes the species formerly known as Pterodrilus durbini Ellis, is effected in order that an account of the anatomy of this species and a related form from Kentucky may be offered toward the completion of the task of understanding the evolutionary relationships of these interesting epizoans on decapods. Moore (1895a), in a paper entitled a remarkable discodrilid, established the genus Pterodrilus to receive the species P. alicicornus from the mountains of western North Carolina and P. distichus from western New York. The most obvious external features of these species are the dorsal bands and projections borne on the major annulations of certain body segments. Subsequently, Ellis (1918, 1919) recognized two other species of branchiobdellid worms with similar dorsal ridges or ridges and processes and assigned them to the genus Pterodrilus. He failed, however to give the detailed and accurate account of the reproductive system which Moore presented for his species. I have found that the internal anatomy of P. durbini is markedly at variance with that of the species Moore included in Pterodrilus, and this worm deserves, perhaps even more than P. alcicornus and P. distichus, to be described as remarkable. The bursa is quite unlike that of the species of Pterodrilus, there is no spermatheca, and the clitellum is developed to an extent not equalled in any other known American branchiobdellid. Since Ellis' original description of P. durbini, the only other reference to the species is Goodnight's (1940) statement that the single specimen examined by him agreed closely with Ellis' description. Goodnight said nothing as to the provenance of the specimen he saw.