• ALGAE
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• v.32 no.1
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• pp.15-28
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• 2017

Morphological, molecular and chromosomal studies were carried out on Tauya basicrassa, an endemic kelp species distributed on the northern continental coast of the Sea of Okhotsk in Russia. The sporophytes of T. basicrassa grow up to 3-6 m long, 1.8-2.2 m wide, and 6.5-7 kg wet weight. The thallus has a blade with very thick narrow basal portion and thinner and much broader upper portion, which usually splits into 3 bullated lobes. A dwarf laminariacean alga, which did not show any morphological similarity to the other species of the order Laminariales, was found from the same locality. The blade of this alga is thin and soft, reached 26-34 cm long and 6-6.5 cm wide and had 4 longitudinal rows of bullations that covered the entire blade. Molecular analysis showed that the dwarf alga has 100% sequence identity in plastid-encoded RuBisCo spacer, mitochondrial cytochrome c oxidase subunit 1 and nuclear-encoded rDNA genes with normal sporophytes of T. basicrassa, indicating that they are different life forms of the same species. Fluorescent DAPI staining showed that the nucleus in the normal sporophyte was 50-65% larger than those of the dwarf ones. Chromosome count using acetocarmine staining showed n = ca. 20 for the normal sporophytes of T. basicrassa and n = ca. 10 for the dwarf one. These results suggest that the dwarf thallus is a haploid parthenosporophyte of T. basicrassa, which developed in nature. This is the first evidence of parthenosporophytes of the laminariacean algae occurring naturally in the field.

• ALGAE
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• v.33 no.1
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• pp.37-48
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• 2018

Alaria is the second largest genus of the Laminariales, which is distributed far into the northern Pacific and Atlantic oceans. Due to its high morphological plasticity, over 100 specific and sub-specific names have been used in Alaria, this has been tailored down to the present 17 species through morphological revision and molecular phylogenetic analysis. Endemic species of Alaria from Russian Far East have not been thoroughly revised since their original description, and few of them were confirmed using molecular data until recently. We carried out morphological and molecular studies on A. paradisea which is an endemic species distributed on the Kurile Islands, first described by Miyabe and Nagai in 1932 as Pleuropterum paradiseum. The range of morphological variability and its distribution was re-evaluated using the type specimen as well as other specimens. Analyses of partial mitochondrial cytochrome c oxidase subunit 1 and nuclear-encoded internal transcribed spacer sequences showed that A. paradisea nested within the genus Alaria, but differs morphologically from any other Alaria species in having additional sporophylls with a central midrib (${\beta}-sporophylls$). Our results showed that A. paradisea clearly belongs to the genus Alaria based on DNA data, although the key morphological character that was used to include this species to the genus Pleuropterum, ${\beta}-sporophylls$, is stable and distinguishes it from other Alaria species.