Phylogeny of the Cladophorophyceae (Chlorophyta) inferred from partial LSU rRNA gene sequences: is the recognition of a separate order Siphonocladales justified?

Abstract

Phylogenetic relationships within the green algal class Cladophorophyceae were investigated. For 37 species, representing 18 genera, the sequences of the 5'-end of the large subunit rRNA were aligned and analysed. Ulvafasciata and Acrosiphonia spinescens (Ulvophyceae) were used as outgroup taxa. The final alignment consisted of 644 positions containing 208 parsimony-mformative sites. The analysis showed three lineages within the Cladophorophyceae: Cladophora horii diverged first, followed by two main lineages. The first lineage includes some Cladophora species and genera with a reduced thallus architecture. The second lineage comprises siphonocladalean taxa (excluding part of Cladophoropsis and including some Cladophora species). From this perspective the Siphonocladales forms a monophyletic group, the Cladophorales remaining paraphyletic.

Phylogeny and Molecular Evolution of the Green Algae

“…The Cladophorales (including Siphonocladales) comprises four main lineages, likely from a filamentous marine ancestor (Bakker et al, 1994;Hanyuda et al, 2002;Leliaert et al, 2003;Leliaert et al, 2009a). The marine unbranched, microfilamentous Okellya forms the earliest diverging lineage, followed by the Aegagropila clade, which is often found in highly specialized freshwater habitats (e.g., lake-balls or epizoophytes on turtles and snails).…”

Epizoic Algae from Freshwater Turtles in Nova Scotia

“…Consequently, Cladophora section Basicladia has no nomenclatural standing, even though the species fall within van den Hoek's concept of the genus. Thus, while van den Hoek's morphological concept of the genus Cladophora as including Basicladia may be reasonable, Cladophora is a polyphyletic grouping that includes several well-characterized genera (Leliaert et al 2003). Cladogram topology suggests that Basicladia will be maintained as a generic segregate within a multigeneric Cladophoraceae (Yoshii et al 2004).…”

Phylogenetic analyses of Cladophora vagabunda (L.) C. Hoek (Cladophorales, Chlorophyta) from Brazil based on SSU rDNA sequences

“…The proximity of C. rupestris with the genus Chaetomorpha has been reported in previous papers (Bakker et al 1994, Hanyuda et al 2002. Cladophora rupestris grouped with Chaetomorpha species in the ML analysis inferred from LSU rDNA carried out by Leliaert et al (2003) indicating that, as suggested by Hoek (1982), Chaetomorpha could be considered as a reduced form and not as a primitive sister genus of Cladophora.…”

“…(Cladophorales, Chlorophyta) is composed by a heterogeneous group of species that shows a high morphological plasticity infl uenced by thallus age and habitat. The genus is widespread in marine, freshwater, estuarine and brackish water environments, from temperate to tropical regions (Hoek 1963, Dodds & Gudder 1992, Hoek et al 1995, Hoek & Chihara 2000, Leliaert et al 2003). Taxonomical problems due to morphological plasticity and wide geographical distribution led to the use of molecular biology analyses to study the genus.…”

“…Recently, Leliaert et al (2003) inferred the phylogenetic relationships in Cladophorophyceae based on the large subunit rRNA gene (LSU rDNA) sequences and showed that Siphonocladales forms a monophyletic group while Cladophorales remains paraphyletic.…”