Asterionellopsis tropicalis (Bacillariophyceae): a new tropical species found in diatom accumulations.
The diatom Asterionellopsis glacialis sensu lato forms high-density patches in the surf zone of some sandy beaches worldwide and was until recently considered a cosmopolitan species. With the recent description of four cryptic species, the identity of specimens found in these accumulations remains uncertain. In this study, diatom patches were sampled from two sandy beaches of the Brazilian coast: one tropical (Futuro Beach, 3° S; 38° W) and one subtropical (Cassino Beach, 32° S; 52° W). Fine structure of frustules and the sequencing of three phylogenetic markers revealed the subtropical strains to be A. guyunusae and the tropical strains to be a new species, here described as Asterionellopsis tropicalis sp. nov. A. tropicalis was differentiated morphologically by the number of striae in 10 μm at the foot pole and head (39-44; 38-45, respectively), from A. lenisilicea (46-55; 46-64), A. maritima (46-51; 46-60), and A. thurstonii (42-58; 55-70). The number of striae at the head region of the valvocopula (10 μm) helped to distinguish A. tropicalis (56-62) from A. guyunusae (61-64), but A. tropicalis was morphologically undistinguishable from A. glacialis. The sequence divergence from other identified Asterionellopsis species was 13%-16% (Cox1), 11%-12% (5.8S + ITS2) and 2%-6% (RbcL), and A. tropicalis formed a distinct monophyletic clade with high support in all analyzed phylogenetic trees (single or multi-locus). This work will aid in the understanding of the ecological and physiological diversity of diatom patches that are key to the trophic webs of sandy beaches.
Institute of Oceanography, Federal University of Rio Grande - FURG, Av. Itália, km8, CEP 96203-900, Rio Grande, Brazil.
Andréa de Oliveira da Rocha
AO
Franco
Department of Oceanography and Limnology, Federal University of Rio Grande do Norte-UFRN, Av. Senador Dinarte de Medeiros Mariz, s/n, Praia de Mãe Luiza, CEP 59014-002, Natal/RN, Brazil.
Ng Haig
NH
They
Institute of Water Sciences and Technology, Federal University of Oeste do Pará - UFOPA, Av. Mendonça Furtado, 2946, CEP 68040-050, Santarém, Brazil.
Luis Gustavo de Castro
LG
Canani
Institute of Marine Sciences, Federal University of Ceará - UFC, Av. da Abolição, 3207, CEP 60165-081, Fortaleza, Brazil.
Rodrigo
R
Maggioni
Institute of Oceanography, Federal University of Rio Grande - FURG, Av. Itália, km8, CEP 96203-900, Rio Grande, Brazil.
Clarisse
C
Odebrecht
D020418:Algal Proteins / Q000235:genetics; D001938:Brazil; D017377:Diatoms / Q000145:classification* / Q000235:genetics; D017753:Ecosystem; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity
D020418:Algal Proteins
Cryptic species; araphid diatom; diatom patches; phylogeny; surf zone