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Systematic studies were undertaken on the Caloglossa continua (Okammura) King et Puttock complex from Japan, Singapore, and Austriala, based on morphology and reproductive compatibility. Specimens from Japan had two to six cell rows derived from a nodel axial cell, at the margin opposite the branch, whereas those from Austraila possessed only a single cell now. Specimens from Singapore formed one to four cell rows per nodal axial cell and always contained at least one single cell row on any one thallus. These differences were maintained in cultural materials over a range of temperagtures or salinities. Type material of C. continua had the same morphology as the Japanese specimens in this study. Carpospores discharged from the Japanese isolate germinated at 10°C, whereas those from Singapore and Australia died at this temperature. In hybridization experiments, the Japanese entity was completely nonfertile with both the Singaporean and Australian isolates. Many pseudocystocarps were produced in the crossing between the make from Australia and the female from Singapore, although the reciprocal combination did not produce any such structures. On the basis of the discontinuous morphology coupled with the complete reproducture isolation, the entiries from Singapore and Australia are described here as C. monosticha sp. nov. The entiries with multiple cell rows likely expanded their geographic range from tropical regions, where the majority of Caloglossa species are now distributed, to high-latitude regions, and such an expansion would be associated with acquining low-temperature tolerance. [ABSTRACT FROM AUTHOR]

Reports on the use of morphological comparisons, hybridization experiments and molecular phylogenetic analyses using the RUBISCO spacer region on 12 populations of red algae Caloglossa leprieurii and C. apomeiotica in order to identify their relationships. Indication that the asexual species was derived from sexual plants of the multiple cell row type; Correlation of reproductive compatibility with genetic distance rather than geographical distance.