Studies in the New Zealand Aneuraceae

Abstract

The New Zealand Aneuraceae were investigated and the New Zealand species of the genus Riccardia S.F. Gray revised. Twenty seven species of Riccardia are fully described, illustrated and lectotypified where necessary. Notes and figures for five members of Aneura Dumortier (A. ?pinguis Dumortier, A. alterniloba (Hooker f. et Taylor) Taylor var. alterniloba, A. ?lobata (Schiffner) stephani subsp. australis Schuster, A.?subaquatica Schuster and A. aff. novaguineensis Hewson) are presented. Of the twenty seven Riccardia species studied nineteen have been previously described (five new recombinations from Aneura have been made; Riccardia papulosa (Stephani) comb. now., R. aequitexta (Stephani) comb. nov., R. pusilla (Stephani) comb. nov., R. alba (Colenso) comb. nov. and R. australis (Hooker f. et Leveille) comb. nov.) and eight are new names (one of which, R. exilis sp. nov., has been erected because the name under which it had been placed is already occupied). Relevant material and type specimens of taxa from South America, Australia, New Caledonia, the Pacific and Indonesia were examined during the course of this revision. Although approximately one third of the species described are new, the placement of a number of other names into synonymy has maintained the number of species at about the same level as before the revision. With the exception of Riccardia brevala sp. nov. the new species are from alpine/subalpine areas, a group of habitats which appear to be grossly under represented in available collections. The variation in most morphological features such as cell size, thallus width and thickness; cell wall thickness; epidermal wall sculpturing; stolen, gemmae and sometimes papillae production and in oilbodies is considerable. Variation is such that a suite of characters usually needs to be used to make a positive identification. Even species such as Riccardia cochleata (Hooker f. et Taylor) O. Kuntze which normally has a distinctive growth form and heavily thickened thallus margins may produce standard Riccardia type thalli and branching patterns (creeping, indeterminate growth with no differentiation within the thallus) when growing in certain (very wet) habitats. The validity of some of the sections and subgenera that are well represented in the New Zealand flora is discussed (in particular section Alcicornia of the subgenus Riccardia and the subgenus Phycaneura). The New Zealand taxa are provisionally placed within the divisions currently used and an artificial key to the species described is presented. Although modified multivariate analysis in conjunction with careful character selection does support previously established subgeneric taxa these are weakly defined and depend on a few key characters. Analysis using a broad base of OTU's has proved unsatisfactory for indicating relationships and also masks the key interspecific differences. It does, however, suggest that the genus is a relatively coherent one and that subgeneric groupings should only be established when they can be supported by a wide range of morphological characters.