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A taxonomic revision of Lobophora based on molecular phylogenetic analyses of rbcL and cox3 gene sequences as well as anatomical observations was carried out, mostly based on specimens collected from eastern Asia and southeastern Australia. In the molecular phylogenetic analyses, nine major clades supported by high bootstrap values were recognized. In combination with evaluation of morphological characters, four clades were concluded to be new species. The Australian species L. australis sp. nov. possessed erect thalli with sporangial son scattered on the ventral surface and had a closer phylogenetic relationship with another Australian species, L. nigrescens, but it was distinguished from the latter in having fewer layers of cortical cells and smaller sporangia. The Asian species L. crassa sp. nov., L. pachyventera sp. nov. and L. asiatica sp. nov. possessed decumbent thalli with sporangia scattered on the dorsal surface. Among the three prostrate species, L. crassa had a considerably thicker thallus with four to five cortical layers, L. asiatica had a thinner thallus with two cortical layers, and L. pachyventera differed from another two species by its three-layered ventral cortex and well-developed anchoring rhizoids. [ABSTRACT FROM AUTHOR]

Chara braunii is a charalean species that grows in a range of aquatic habitats from shallow water in paddy fields to the bottom of deep lakes. More than 30 infraspecific taxa have been proposed within this species because of its morphological variability. In order to reexamine the infraspecific taxa and habitat preference of C. braunii, we carried out molecular phylogenetic analyses and quantitative measurements of morphological characters used for infraspecific taxa, based on samples collected from various habitats and localities in Japan. Sequence data from the gene encoding the large subunit of Rubisco (rbcL) and the intergenic spacer regions between the beta subunit of the ATP synthase and rbcL genes demonstrated two robust clades (groups A and B). Samples of group A were collected mainly from shallow aquatic environments (< 15 cm in depth) such as paddy fields, while those of group B were mainly composed of samples found in deep aquatic environments (> 1 m in depth) such as lakes or ponds. Groups A and B therefore seem to represent closely related entities that have recently differentiated and might adapt to two different aquatic environments. However, the morphological measurements suggested these groups can be delineated by neither of the traditional diagnoses that were different between infraspecific taxa of Japanese plants of C. braunii. [ABSTRACT FROM AUTHOR]

Examination of Grammatophora marina from rough and clonal cultures showed that cell size changes were more flexible than is generally reported for diatoms. Allogamous sexual auxosporulation took place through copulation between small male cells and larger female cells, but only in mixed rough culture and never in clonal cultures. Auxospores were also formed without copulation in clonal cultures ('uniparental auxosporulation') and these, like sexual auxospores, developed through formation of a perizonium, which consisted of a series of transverse bands. All of these bands, including the primary band, were open. Circular scales were present in the auxospore wall before initiation of perizonium formation and irregular, elongate structures lined the suture of the transverse perizonium. Perizonium and scales resembled those of another araphid pennate diatom, Gephyria media. Initial cells were formed within the perizonium and consisted of an initial epivalve with a simplified structure, an initial hypovalve (formed beneath the perizonium suture) and a third, normally structured valve formed beneath the epivalve; the epivalve was then sloughed off. Initial cells of similar configuration but often aberrant morphology could also be formed through expansion from vegetative cells, without involvement of a perizonium. Vegetative cells were also capable of limited enlargement through simple expansion without formation of an initial cell, and abrupt size reduction. Cell size ranges in populations from different regions suggest that G. marina may contain pseudocryptic species. [ABSTRACT FROM AUTHOR]