Amylax diacantha Meunier, 1919

Nunes, Caio Ceza da Silva, Susini-Ribeiro, Sylvia Maria Moreira & Cavalcante, Kaoli Pereira, 2019, Dinoflagellates in tropical estuarine waters from the Maraú River, Camamu Bay, northeastern Brazil, Check List 15 (5), pp. 951-963 : 956

Amylax diacantha Meunier, 1919

Figure 4A, B

Brazil, Estuary of Maraú River: River Zone Station 1, 14°06′33″S, 039°02′48″W, IX.2006 (HUESC 24039); Mixing Zone Station 2, 14°04′52″S, 038°59′12″W, XI. 2006 (HUESC 24047).

Cell pentagonal, epitheca conical gradually reduced in a short apical horn, hypotheca trapezoid with two divergent antapical spines, surface of thecal plates reticulate with longitudinal ridges, cingulum descending, no overlapping. TL: 30.5 μm; CW: 19.4 μm (n = 2).

Taxonomic remarks: Amylax diacantha , when transferred to the genus Gonyaulax , was renamed Gonyaulax verior Sournia ( Sournia 1973) , as the combination

Gonyaluax diacantha Athanassopontos 1931 for another taxon had priority under the rules of International Code of Nomenclature for Algae, Fungi, and Plants (ICN). Morphologically, Amylax diacantha (Po, 4′, 2a, 6″, 6c, 7s, 6‴, 1p, 1′′′′) does not fit into the typical Gonyaulax tabulation (Po, 3′, 2a, 6″, 6c, 7s, 6‴, 1p, 1′′′′). Furthermore, that species shows marginal pore in the plate 1′ near 4′ and 2a and the orientation of sulcal plates are of the L-type (following Fensome et al. 1993), so it should not be attributed to the genus Gonyaulax ( Matsuoka et al. 1988; Zonneveld and Dale 1994). Phylogenetically, the species is closer to Lingulodinium Wall and less related to Gonyaulax sensu stricto ( Koike and Takishita 2008). Therefore, the combination A. diacantha should be preferred for this taxon and the relationships between Amylax and Lingulodinium should be reviewed.

Distribution in Brazil: coastal regions of Bahia ( Affe 2012; Santana 2012), São Paulo, Rio de Janeiro and Rio Grande do Sul; cited as Gonyaulax verior ( Flora do Brasil 2019).