Ceratium furcoides (Levander) Langhans (1925: 602)

Bustamante-Gil, Carolina, Boltovskoy, Andrés, Rengefors, Karin, Tavera, Rosaluz, Amat, Eduardo & Ramírez-Restrepo, Jhon J., 2021, Checklist, new records, and taxonomic annotations of freshwater thecate dinoflagellate (Dinophyceae) in Colombia, Phytotaxa 509 (2), pp. 135-167 : 140

Ceratium furcoides (Levander) Langhans (1925: 602) . Figure 2

Basionym: Ceratium hirundinella var. furcoides Levander (1894: 53) .

Synonyms:

Ceratium furca var. lacustre in L. Maggi (1880:128)

Ceratium handelii Skuja in Handel-Mazzetti (1937: 48)

Ceratium hirundinella in Cardozo et al. (2005: 85)

Ceratium hirundinella in Martínez-Silva (2015: 16)

Ceratium hirundinella in Pedroza-Ramos and Rozo-Suárez (2017:59)

Dimensions: TL: 132–289 µm, Td: 27–53 µm

Cell shape: Spindle cells on its contour and strongly flattened dorsoventrally ( Fig. 2A ). Triangular epitheca that narrows anteriorly extending into a long horn. Hypotheca wide and short, provided with two or three horns of different length. The antapical horn (the central) is the longest and is formed by antapical plates. Narrow Cingulum with 5 cingular plates.

Thecal characteristics: Tabulation, Po, 4ʹ, 5ʹʹ, 5C, 6S, 5ʹʹʹ, 2ʹʹʹʹ. The epithecal plates form the apical horn. The 4ʹ plate is the shortest of the set and does not reach the apex of the horn ( Figs. 2B and 2C ). The short 4ʹ plate is the main diagnostic character which differentiates C. furcoides from its sister species C. hirundinella with which it is often confused ( Fig. 2D ).

Ornamentation: Thecal plates are covered by a strong relief reticulum with pores in the center of the alveoli ( Fig. 2D ). The apical horn apex shows a crown of small spikes ( Fig. 2E ).

Localities: Guatapé, La Fe, Piedras Blancas, Porce II, Porce III, Riogrande II reservoirs in North-West, Chuza, San Rafael, De La Regadera reservoirs, and La Tota lake in Central Colombia.

Comments: The specimens studied substantially agree with the morphological descriptions of Almanza et al. (2016), Carty (2014) and Moestrup & Calado (2018). Length and the trans-diameter measures show a higher variation compared to North American specimens ( Carty 2014), but less than in European ( Moestrup & Calado 2018) and Chilean specimens ( Almanza et al. 2016) ( Table 3). Both, two and three hypothecal horns were found often in specimens from the same location, being the right post-cingular horn, when present, remarkably variable in the length.

World distribution: Worldwide distribution in temperate-tropical regions. In Asia, Europe, North America and South America in Argentina, Bolivia, Brazil, Colombia, Chile, Paraguay, and Uruguay ( Almanza et al. 2016; Meichtry de Zaburlin et al. 2016; Moestrup & Calado 2018; Morales 2016).

Figures

FIGURE 2. Morphology of C. furcoides. A. LM view, bar= 20 µm. B. Apical plates, MO view. C and D. Plates 1ʹ and 4ʹ, SEM view, bar= 20 µm and 10 µm, respectively. E. Apical pore, SEM view, bar= 1 µm.