Some marine diatoms from the Australian region, especiallly from Port Phillip Bay and Tropical North-eastern Australia. 2. Survey of the genus Palmeria and of the family Lithodesmiaceae including the new genus Lithodesmioides.

Abstract

Based on plankton samples collected in 1970 and on a survey of the literature, the Australian members of the genus Palmeria and of the family Lithodesmiaceae are critically listed or described. Both species of Palmeria are new for the Australian region, as are one species each of Lithodesmium and of Ditylum, two species of the genus Lithodesmioides, one species plus one variety of Bellerochea, as well as one species and one form of Neostreptotheca. Lithodesmium duckerae, Lithodesmioides polymorphum and L. minutum, Ditylum buchananii, Bellerochea horologicalis var. recta and Neostreptotheca torta and its fo. triangularis are described for the first time. Palmeria ostenfeldii, a species associated with an epiphytic ciliate, is sep- arated from P. hardmaniana. In Ditylum brightwellii, the proportion of thecae with the slotted versus the fimbriate form of the marginal ridge is shown to be probably influenced by the ambient water conditions. In the same species, the ontogenies of the resting spores (including germi- nation) as well as of the gametes are described. Lithodesmioides presents new instances of fissipariety (split wall character) in both of its species. 'Simple pores', which have recently been demonstrated by Li and Volcani to be distinct in origin from areolae, are common in all described species of Lithodesmium, Lithodesmioides and Ditylum in two forms as either 'branching point pores' or 'intracostal pores'.