Molecular Phylogeny of the Marine Planktonic Dinoflagellate Oxytoxum and Corythodinium (Peridiniales, Dinophyceae)

Abstract

Abstract. The dinoflagellate genera Oxytoxum and Corythodinium that account for more than fifty species are widespread in warm oceans. These genera have been considered synonyms and thecal plate designations varied among authors. Several planktonic and sand-dwelling genera have been placed within the Oxytoxaceae. We obtained the first molecular data based on small subunit (SSU) rRNA gene sequences of Oxytoxum and Corythodinium, including the type species (O. scolopax and C. tessellatum) and C. frenguellii and C. cristatum. The three species of Corythodinium branched together a strong support [bootstrap (BP) of 98%]. This formed a sister clade with moderate support (BP 75%) with O. scolopax that supported the generic split. Oxytoxaceae should exclusively remain for Oxytoxum and Corythodinium, as an independent group, unrelated to any other known dinoflagellate. Oxytoxum was characterized by spindle-shaped cells with an anterior narrow epitheca, an apical spine and little cingular displacement. Corythodinium exhibits relatively broad cell shapes, with wider epitheca and greater cingular displacement, and an obovate or pentangular anterior sulcal plate that noticeably indented the epitheca. This suggested the need of new combinations for species that were described as Oxytoxum and possessed the characteristics of Corythodinium.

Field observations on rare or unnoticed dinoflagellates from the Argentine Sea

“…Both genera are morphologically similar but can be distinguish by the position of the cingulum, always anterior in Oxytoxum and median or anterior in Corythodinium, and by the larger and broader epitheca in Corythodinium (Taylor, 1976). Although some species possess intermediate characteristics between both genera; molecular data support the generic separation (Gómez et al, 2016). Within the genus Oxytoxum, Dodge and Saunders (1985) designated O. laticeps as the type species of Section Excavatum (II), which comprises species with a reduced and domed epitheca and sulcus deeply excavated and partly covered by a large list composed of extensions of Sd and 6'' plates and by a list which is an extension of 1''".…”

“…5C, D). It is an autotrophic species (Gómez et al, 2016). Dimensions: length average 16.7 µm ± 1.4, width average 12.4 µm ± 1.8 (n = 20).…”

“…Observations. Oxytoxum and Corythodinium are the only two genera within the family Oxytoxaceae, which form their own clade within the dinokaryotic dinoflagellates according to molecular data (Gómez et al, 2016). Both genera are morphologically similar but can be distinguish by the position of the cingulum, always anterior in Oxytoxum and median or anterior in Corythodinium, and by the larger and broader epitheca in Corythodinium (Taylor, 1976).…”

Supplementary material to "The onset of the spring phytoplankton bloom in the coastal North Sea supports the Disturbance Recovery Hypothesis"

“…Using this information and selected cell shape formulas from Olenina et al (2006), we calculated Vc. Only for Nézan et al (2012) and Gómez et al (2016) minimum-maximum Vc were calculated and, in these cases, mean Vc is also reported. Table S2.…”

Comparação da variação da diversidade taxonômica e de traços funcionais em comunidades fitoplanctônicas em duas enseadas do litoral norte de São Paulo

“…A quantificação dos traços classificados nesse estudo seguiu o proposto por Moser et al (2017), sendo os registros reportados como presença ou ausência. Os traços foram determinados com o auxílio da literatura especializada contendo informações sobre características dos gêneros identificados (Guiry e Guiry, 2021; Rodríguez- Gómez et al, 2021;Sathish et al, 2021;Lavanya et al, 2020;Velázquez-Suárez et al, 2020;Díaz et al, 2019;Kaczmarska et al, 2019;Sukenik et al, 2019;Ryabushko et al, 2019;Yunes, 2019;Godrijan et al, 2018;Pacheco et al, 2016;Cros e Estrada, 2013;Nanjappa et al, 2013;Mann et al, 2017;Saldarriaga e Taylor, 2017;Eikrem et al, 2016;Gómez, et al, 2016;Dimiza et al, 2014;McCartney et al, 2014;Komárek e Johansen, 2015;Anderson et al, 2012;Harrison et al, 2011;Gómez et al, 2010;Haraguchi e Odebrecht, 2010;Al-Kandari et al, 2009;Kaczmarska et al, 2009;Gribble et al, 2009;Escalera et al, 2007;Baek et al, 2006;Tenenbaum e Gomes, 2006;Witon e Witkowski, 2006;Malinverno, 2004;Montresor et al, 2003;Hargraves, 2002;Litaker et al, 2002;Hasle, 2001;Seo e Fritz, 2001;Cox, 1999;…”