A molecular and morphological reinvestigation of topotype specimens of Calliblepharis occidentalis (Cystocloniaceae, Rhodophyta)

ABSTRACT

Calliblepharis occidentalis was originally described from northeastern Brazil and later reduced to synonymy with C. fimbriata from South Africa. It was later reinstated, but phylogenetic relationships with other congeners and several morphological characters remain poorly understood. In the present article, topotype specimens of C. occidentalis were reinvestigated using molecular, morphological and anatomical data, and its phylogenetic position was inferred on the basis of rbcL and SSU rRNA. Calliblepharis occidentalis was characterised mainly by the axial filament surrounded by medullary cells, weakly developed rosettes in the outer cortex and carposporophytes with central columns. Our molecular phylogeny showed that C. occidentalis is distinct from C. fimbriata (rbcL divergence of 4.5%). Relationships among the 10 species currently assigned to Calliblepharis remain unresolved and whether they form a monophyletic clade is uncertain. Our results suggest that this genus is composed of five morphological groups, here called Calliblepharis sensu lato, based on vegetative and reproductive features such as type of placentation in the carposporophyte, axial filament arrangement and formation of rosettes. The morphological groups might represent different genera, but this hypothesis needs to be tested with better resolved phylogenies based on more comprehensive gene datasets.

KEYWORDS:

• Brazil
• Gigartinales
• Macroalgae
• Morphology
• Phylogenetics
• rbcL
• Reproductive morphology
• SSU rRNA
• Taxonomy

ACKNOWLEDGEMENTS

We acknowledge Mi Yeon Yang, Razy Hoffman and Gary Saunders. Mi Yeon Yang provided sequences of C. saidana, and Razy Hoffman and Gary Saunders provided sequences of C. rammediorum, used in this work. The authors are grateful to the reviewers and to Giuseppe Zuccarello, whose suggestions helped to improve this article.

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Additional information

Funding

This work was partially supported by research grants from the Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP (2016/50370-7) and from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq 440523/2015-0). LPS thanks CNPq for the postdoctoral fellowship (PROTAX 150848/2015-3) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil) for a PhD fellowship (23038.000077/2010-38). MTF thanks CNPq for a productivity fellowship (304899/2017-8). PDT acknowledges support from the postdoctoral program ‘Axudas de apoio á etapa de formación posdoutoral, Xunta de Galicia’.