Peridinium willei Huitfeldt-Kaas (1900:5)

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 : 158-160

Peridinium willei Huitfeldt-Kaas (1900:5) . Figure 16

Synonyms:

Peridinium alatum in Garbini (1902: 122)

Peridinium willei var. carinthiacum in Beck-Mannagetta (1931: 229)

Dimensions: L: 49–74 µm, Td: 32–67 µm.

Cell shape: Highly variable, from sub-spherical to deflated ball shape, that is, with a strong sinking in the ventral part of the epitheca as in P. willeli f. lineatum ( Fig. 16 ).

Thecal characteristics: Tabulation, 4ʹ, 3a, 7ʹʹ, 5C, 6S, 5ʹʹʹ, 2ʹʹʹʹ. Without apical pore. In the spherical specimens, the plates are more uniform in the term of development of their axis. Plate 1ʹ very variable, from an almost rhombic shape ( Fig. 16B ) to fan-shaped ( Fig. 16C ). Plate 2a is of hexa symmetrical type ( Figs. 16D and 16E ). The adcingular plates form cingular lists typical for the genus.

Cingulum and sulcus: Descendent cingulum. The sulcus penetrates slightly into the epitheca and reaches the antapex, being narrower in the anterior part and wider posteriorly.

Ecdysial opening: As in most of the species of the genus ( Boltovskoy 1973b) the opening is a result of the detachment of the seven dorsal plates of the epitheca.

Ornamentation: The main thecal plates have a relief reticulum formed by solid cords and nodules, with pores inside the alveolus. Tabular margins bordered by slightly prominent marginal ridges. A remarkable difference with the other species of the genus, except with P. limbatum , is the development of three hyaline lists arisen from the marginal ridges of the anterior edges of the plates 2ʹ+4ʹ, 1a+3ʹ+3a and 2a. ( Fig. 16 C-F). These lists are continuous strips situated perpendicularly to the sagittal plane. At the antapex there are also lists, located on eiher side of the posterior end of the sulcus ( Fig. 16G ).

Localities: Riogrande II reservoir in North-west, De La Regadera reservoir, Chisacá, La Cristalina, Media, and El Pozo lakes in central Colombia.

Commentaries: Two forms of this species were found in the analyzed samples, the willei form with 1ʹ plate expands laterally in an extraordinary way ( Fig. 16C ) and the lateral epithecal plates and especially those of the apical region are tapered, forming two strips that run the epitheca from side to side ( Figs. 16E and 16F ). In this case, 1ʹʹ plate is three times shorter than 7ʹʹ plate ( Fig. 16C ) and cingular lists are more prominent. These specimens were found in Chisacá and El Pozo (lakes) and were larger than those of Boltovskoy (1999a). The lineatum form ( Fig. 16A ) with 1ʹ plate rhombic shape ( Fig. 16B ), these were found in Riogrande II and De La Regadera (reservoirs), La Cristalina and Media (lakes), was in the range of the measures cited by the same author ( Table 9) and larger than those reported in previous taxonomic studies ( Hansen & Flaim 2007; Huitfeld-Kaas 1900; Ling et al. 1989; Moestrup & Calado 2018).

World distribution: This species has a wide distribution in Europe, Asia and USA ( Moestrup & Calado 2018). In Central and South America in Argentina ( Boltovskoy 2003), Bolivia ( Iltis & Couté 1984), Brazil ( Fonseca & Bicudo 2008; Cardoso et al. 2010), Colombia ( Cardozo et al. 2005; Donato-R 2001), and México ( Löffler 1972).

Locality L (µm) Td (µm)

De La Regadera 55–74 43–62

Riogrande II 53–63 47–52

La Cristalina 60–70 51–67

Media 53–59 39–48

El Pozo 49–61 32–53

Total Variation 49–74 32–67

Figures

FIGURE 16. Peridinium willei f. willei: A. Ventral view. B. Plate 1’. Bar=10µm. P. willei f. lineatum: C. Ventral view. D. Dorsal view. E. Dorsal apical view. F. Lateral view. G. Antapical view.