STUDIES OF THE LIAGORACEAE (RHODOPHYTA) OF WESTERN-AUSTRALIA - GLOIOTRICHUS-FRACTALIS GEN ET SP-NOV AND GANONEMA-HELMINTHAXIS SP-NOV

Two new taxa of Liagoraceae (Nemaliales) are described from Western Au stralia. Gloiotrichus fractalis gen. et sp. nov. has been collected fr om 3-20 m depths at the Houtman Abrolhos, Western Australia. Plants ar e calcified, extremely lubricous, and grow to 17 cm in length. Carpogo nial branches are straight, 6 or 7 cells in length, arise from the bas al or lower cells of cortical fascicles, and are occasionally compound . Branched sterile filaments of narrow elongate cells arise on the low er cells of the carpogonial branch prior to gonimoblast initiation, at first on the basal cells, then on progressively more distal cells. Fo llowing presumed fertilisation the carpogonium divides transversely, w ith both cells giving rise to gonimoblast filaments. The distal cells of the carpogonial branch then begin to fuse, with fusion progressing proximally until most of the cells of the carpogonial branch are inclu ded. As fusion extends, the filaments on the carpogonial branch are re duced to the basal 2 or 3 cells. The gonimoblast is compact and bears terminal carposporangia. Spermatangial clusters arise on subterminal c ells of the cortex, eventually displacing the terminal cells. The sequ ence of pre- and post-fertilisation events occurring in the new genus separates it from all others included in the Liagoraceae, although it appears to have close affinities with the uncalcified genus Nemalion. Ganonema helminthaxis sp. nov. was collected from 12 m depths at Rottn est Island, Western Australia. Plants are uncalcified and mucilaginous , the axes consisting of a few (< 10) primary medullary filaments, eac h cell of which gives rise to a cortical fascicle at alternate forks o f the pseudodichotomies borne on successive medullary cells. Subsidiar y (adventitious) filaments and rhizoids comprise the bulk of the thall us. Carpogonial branches are straight, (3-)4(-6) cells in length, aris e on the basal 1-4 cells of the cortical fascicles, and are frequently compound. Carposporophytes develop from the upper of two daughter cel ls formed by a transverse division of the fertilised carpogonium. Asce nding and descending sterile filaments girdle the carpogonial branch c ells and arise mostly on the supporting cell prior to fertilisation. G anonema helminthaxis is the first completely non-calcified member of t he genus, and its reproductive and vegetative morphology supports the recognition of Ganonema as a genus independent from Liagora. Liagora c odii Womersley is a southern Australian species displaying features of Ganonema, to which it is transferred.