Morphological and taxonomic studies of selected genera from the tribe Amansieae (Rhodomelaceae, Rhodophyta)

Abstract

The morphology and taxonomy of seven poorly understood species from five genera of the Amansieae are documented. The basic characters by which genera of the tribe are currently distinguished include: (1) the number of pericentral cells; (2) the degree of thallus flattening and lateral wing development; (3) the type of endogenous branching; (4) branch and/or spine features of blade margins; and (5) the position of reproductive axes. Two Australian species of Enantiocladia Falkenberg, E. robinsonii (J.Agardh) Falkenberg and E. axillaris Falkenberg, do not conform to the defining features of Enantiocladia as exhibited by specimens of the type species examined in this study, and the two new genera Plectrophora and Nanopera are proposed to accommodate them. The genusKuetzingia Sonder has previously included four species, the three Australian endemics K. canaliculata (Greville) Sonder, K. angusta (Harvey) and K. pectinella (Harvey) Falkenberg, and the South African K. natalensis J.Agardh. Phoographs in AD of the holotype specimen of Kuetzingia pectinella indicate that it is an earlier taxonomic synonym of Enantiocladia robinsonii and is thus the type species of the genus Plectrophora Wilson et Kraft. Kuetzingia natalensis is also transferred to Plectrophora, leaving Kuetzingia as an Australian-endemic genus of two species. A rare tropical-Atlantic species previously credited to Protokuetzingia, P. schottii Taylor, is provisionally transferred to Enantiocladia because the number of its pericentral cells and the position of its procarps conform to that of the Caribbean type species of Enantiocladia, E. duperreyi (C.Agardh) Falkenberg. This transfer leaves Protokuetzingia monotypic and also an Australian-endemic genus. A review of the genera of the Amansieae is given and conclusions are drawn as to the generic criteria most likely to be important within the tribe.