The red algal genus Scinaia (Galaxauraceae, Nemaliales) from Australia

Abstract

Seven species of the genus Scinaia (Nemaliales, Galaxauraceae) are reported from Australia, including three new species (S. aborealis, S. howensis, S. proliferata), one new record (S. caribaea, previously known only from Haiti) and three previously recorded species [S. australis, S. moniliformis, S. tsingalensis (as S. moretonensis)]. Habits, vegetative morphology and reproductive development have been examined in all seven species and compared with taxa of Scinaia from elsewhere. As a result, S. indica (previously known from India) and S. moretonensis are reduced to synonymy with S. moniliformis and S. tsingalensis, respectively. The reproductive development of the seven species is typical of the genus, with the exception of S. aborealis and S. proliferata which produce numerous sterile branches on their hypogynous cells rather than the two sterile branches (one one-celled, one two-celled) uniformly present in other members of the genus. As these two species retain this apparently primitive condition (numerous sterile branches on the hypogynous cell are also found in Gloiophloea, the probable progenitor of Scinaia), it is postulated that they are closely related to the forerunners of the genus. Scinaia proliferata produces cortical utricles of mixed sizes in a manner similar to S. forcellata (the type species of the genus) and probably arose early in the evolutionary line that produced that species and all of those previously included in Pseudoscinaia and Pseudogloiophloea. Scinaia aborealis produces uniformly sized cortical utricles and probably occupies a similar position in the evolutionary line that produced the remaining species of Scinaia.