THE ULTRASTRUCTURE OF THE SPERMATOZOA OF BUFONID AND HYLID FROGS (ANURA, AMPHIBIA) - IMPLICATIONS FOR PHYLOGENY AND FERTILIZATION BIOLOGY

Comparison of the spermatozoa of Bufo marinus, six Australian species of the family Hylidae, and the myobatrachine Adelotus brevis, with tho se of 41 other species of frogs, in a total of 12 investigated familie s allows the following phylogenetic inferences: the bufonoids (myobatr achids, leptodactylids, hylids, and bufonids) form a monophyletic asse mblage with a single synapomorphy: the presence of a conical subacroso mal perforatorium. This structure is analogous to, rather than homolog ous with, the perforatorium in archaeobatrachians, which differs notab ly in being an endonuclear structure. The hylid-leptodactylid-bufonid assemblage is the sister-group of the Myobatrachidae (Australian 'lept odactylids'). Myobatrachids are distinguished by two, albeit weak, syn apomorphies, the presence of well-defined pericentriolar material, and the extension of the axial rod up the centriolar fossa, the latter co ndition approached in the bufonid Nectophrynoides. The bufonid, leptod actylid (sensu strictu), and hylid families are united, and separated from myobatrachids, by a single synapomorphy: a thick collar-like cyto plasmic sheath that emanates from the centriolar region, is separated from the flagellum by a cytoplasmic canal, and contains the mitochondr ia. Litoria fallax, L. gracilenta, and L. lesueuri are associated by a unique synapomorphy, hypermorphosis of the minor fibre (juxta-axonema l fibre), though this is approached in Bufo bufo. However, there is no spermatological evidence supporting the recognition of Australian hyl ids (pelodryadids) as a group distinct from the remaining eubufonoids and, specifically, from the Hylidae. Evidence is presented in support of the tentative proposal that the Lissamphibia were primitively inter nally fertilizing.