Lamprothamnium heraldii sp. nov. (Charales, Charophyta) from Australia: the first dioecious representative of the genus

Abstract

Lamprothamnium heraldii A. García & Casanova sp. nov. (Charales, Charophyta) is a dioecious species collected in Australia. Its dioecious nature and the characteristics of its reproductive organs separate it from other species of the genus. The habit of the male and female plants is similar, and their vegetative morphology is similar in many respects to that of the monoecious species. However, the new species has larger antheridia and oogonia, larger coronula cells on the oogonium, a smaller number of striae and circumvolutions in the oospores and gyrogonites, and different gyrogonite morphology. The new species has been found in ephemeral lakes from the Paroo region in north-western New South Wales (NSW) and south-western Queensland, at the eastern margin of central Australia. Lake Gidgee, NSW, was chosen as the type locality. Lamprothamnium heraldii was also collected from Palaeo Lake, NSW, and Mid-Blue Lake and Lower Bell Lake, Queensland. These habitats are characterized by fluctuating salinity, and can be dry for several years at a time during periods of drought. Healthy populations of L. heraldii were found in salinities ranging from 2 to 25 g l−1 (as total dissolved solids) and pH 7.8–8.4. Scanning electron microscope images of the oospore, oospore ornamentation and gyrogonites are presented, together with photographs of whole plants. The significance of the discovery of a dioecious Lamprothamnium is discussed in relation to the biogeography of charophytes.