On the Morphology and Nature of a Leech of the Genus Philobdella (Hirudinoidea: Macrobdellidae)

Abstract

The morphology of the pharynx and associated structures and the morphology and morphological relationships of organs on the anterior region of the paired male ducts, are typical of the Macrobdellidae. There is no male median region, no female atrium or common oviduct, and a caecate vagina occupies the entire female median region. INTRODUCTION Moore (1901), describing Philobdella gracile (later gracilis, v. Moore, 1959), recognized the dentition as partially the alimentary canal as more closely resembling the canal in Haemopis, etc., and concluded that P. gracilis was primarily macrophagous and an occasional sanguivore. Later (1918, 1959) he grouped Philobdella with Haemopis, and referred (1927) to partial distichodonty as evidence for the derivation of distichodonty from the monostichodont condition. Scriban and Autrum (1934), Pennak (1953), Mann (1962) and others have followed Moore in this association of the two genera, but not Soos (1969), who groups Philobdella with Macrobdella. The male reproductive system in P. gracilis was described by Moore (1901) as lacking a male atrium, by which Moore meant that there was no muscular penis sheath; and the female system was described as having the oviducts opening into the large end of an unpaired organ without the usual features of an albumin gland, common oviduct and vagina. From Moore, I could assess Philobdella only as essentially macrophagous, distichodont, and with mesomorphic amyomeric median regions on the reproductive systems. In assembling the family Haemopidae, Richardson (1969) excluded Philobdella on the basis of the absence of the haemopisoidc morphology on the anterior region of the paired male duct and on the presence of an amyomeric male median region. I did not make the point then that neither Moore's figure of the dentition (1901, pl. xliv, fig. 20) nor the description conformed to distichodonty as known to me and as fully described by Mathers (1954), who gives the first detailed account of a distichodont dentition. Further confusion on the nature of Philobdella comes from Moore's statement (1935) that the Australian Aetheobdella hirudoides approaches Philobdella in the nature of the jaws, teeth and male reproductive structures. I found Aetheobdella to be typically sanguivorous in the form of the jaws, in the pharynx and associated structures. The one resemblance is in a low number of teeth. There are some gaps and other difficulties in Moore (1901). These prevented the determination of a relationship for Philobdella. 1 A study collateral to researches on Australian leeches assisted by a grant from the Nuffield Foundation.