Fragilaria capucina Desmazières (1830

Delgado, Cristina, Novais, M. Helena, Blanco, Saúl & Almeida, Salomé F. P., 2015, Examination and comparison of Fragilaria candidagilae sp. nov. with type material of Fragilaria recapitellata, F. capucina, F. perminuta, F. intermedia and F. neointermedia (Fragilariales, Bacillariophyceae), Phytotaxa 231 (1), pp. 1-18 : 11

Fragilaria capucina Desmazières (1830 , fasc. 10, no. 453) emend. Lange-Bertalot (1980: 747) ( Figs 108–122 , LM)

Type:— FRANCE. Desmazières’ exsiccata set (fascicle 10, no. 453). Lectotype (designated in Tuji & Williams 2006): an individual from BM 81302 located at England finder Q33–1, fig. 6O in Tuji & Williams 2006, isolectotype: TNS BM 81302 .

Morphology:— The valves are linear, with weakly rostrate ends, rimoportulae occur near the poles, two per valve. The apical pore fields are rectangular, bearing neatly arranged rows of poroids. The central area is rectangular to rhombic and the striation is alternate, parallel to slightly radiate towards the apices. The cells have open bands, with a single row of small punctae and the valves present spines. Krammer & Lange-Bertalot (1991) documented three different morphologies found in the type material of F. capucina : one morphology has lanceolate valves “lacking” marginal spines; the second has valves that are linear to lanceolate but relatively shorter than the other morphology and with linking spines. Both morphologies have only one rimoportula per valve, strongly rostrate valve apices and a unilateral central area. The third morphology has linear valves, with a rectangular to rhombic central area and weakly rostrate valve apices (Tuji & Williams 2006) and linking spines. Whereas Lange-Bertalot (in Krammer & Lange-Bertalot, 1991, 2000) considered the morphological variation of this species to be extensive, it appears more reasonable to understand the variation as due to three different species, all present in the same gathering; the morphological variation of Fragilaria capucina s.s. is therefore not so diverse. Valve dimensions: length 28–47 μm, width 3.3–4.2 μm, striae 14–17 in 10 μm in the type material analysed in this study.

Habitat:— Found in a wide variety of environments, in plankton and benthos from lotic to lentic waters, including terrestrial habitats.

Distribution and ecology:— Probably cosmopolitan, although the data are questionable due to confusion with many similar taxa. Inhabits oligo- to mesoeutrophic, weakly acidic to alkaline waters with low to medium electrolyte content.

Recent illustrated references:— Hein (1990), Krammer & Lange-Bertalot (1991, 2000, 2004), Hammer (1995), Kobayasi et al. (2006), Tuji & Williams (2006), Kwandrans (2007), Levkov (2007), Das & Adhikary (2012), Kopalová et al. (2012), Solak & Wojtal (2012), Smith et al. (2013), Waldmann et al. (2014).

Notes:— Desmazières described F. capucina on the label of no. 453 of his exsiccatae “Plantes cryptogames du Nord de la France ” (Desmazières, 1825–1851). The photographs included in this study were made from the type slide BM 81302 housed in the Natural History Museum of London (BM).

Fragilaria intermedia (Grunow) Grunow in Van Heurck (1881: pl. 45, fig. 11) ( Figs 123–131 , LM retrieved from Tuji & Williams (2013))

Basionym: Fragilaria mutabilis var. intermedia Grunow (1862: 55) .

Homotypic synonyms: Staurosira intermedia (Grunow) Grunow (1882: 139) , Fragilaria tenuicollis var. intermedia (Grunow) Van Heurck (1896: 326 ; pl. 30, fig. 844), Fragilaria pinnata var. intermedia (Grunow) Mayer (1919: 196 , pl. 5, fig. 52), Ceratoneis vaucheriae var. intermedia (Grunow) H. Kobayasi (1965: 128 , figs 7–8).

Type:— GERMANY. Stienitzsee. Lectotype (designated in Tuji & Williams 2013): W!, slide 552 with blue label in Grunow collection (pl. 45, fig. 11 in Van Heurck’s annotated copy of Synopsis des Diatomées de Belgique).

Morphology:— The valves have strongly apiculate ends. Rimoportulae occur near the poles, one per valve, and the apical pore fields are rectangular. Valve dimensions: Length 20–39 μm, width 3–4 μm, striae 17–19 in 10 μm, 60–65 punctae in 10 μm ( Tuji & Williams 2008).

Habitat:— Epilithic in calcareous springs and streams, also in lake benthos and plankton.

Distribution and ecology:— recorded worldwide, but probably confused with similar taxa of the Fragilaria capucina / vaucheriae species complex, especially in older references. Ecology poorly known due to the scarcity of reliable data. Seems to prefer meso-to eutrophic waters.

Recent illustrated references:— Wehr (2002), Tuji & Williams (2013).

Notes:— Tuji and Williams (2013) observed individuals on the type slides which agree with the original illustration given in Grunow (1860), and should be considered synonymous with F. vaucheriae , as previously discussed by Petersen (1938). Taxonomic confusion relative to this taxon was caused by the other illustrations in the Synopsis des Diatomées de Belgique, figs 9 and 10 ( Van Heurck 1881), derived from specimens on slide number 31. The specimens on slide 31 have spines and poorly delimited striae, forming long colonies ( Figs 29–42 ). These specimens differ from those on slide 552. However, in some cases figs 9 and 10 from the Synopsis des Diatomées de Belgique ( Van Heurck 1881) from slide 31 have been referred to for identification of F. intermedia (e.g. Patrick & Reimer 1966).

Figures

FIGURES 40–122. LM micrographs of the type materials. 40–75. Fragilaria recapitellata (Grunow) J.B. Petersen, individuals from Kützing’s type material in packet 861, sheet 586 (slide – BM 101312); 76–107. Fragilaria perminuta, type material 2592 in Grunow’s collection (slide W-2011-01898). 108–122. F. capucina Desmazières type material (slide BM! 81302). Scale bar = 10 μm.

FIGURES 123–149. LM micrographs of the type materials. 123–131. Fragilaria intermedia (Grunow) Grunow from Tuji & Williams (2013); 132–149. Fragilaria neointermedia Tuji & Williams (2013) from type material Grunow (slide W-1901-0004076). Scale bar = 10 μm.

FIGURES 2–33. LM micrographs of Fragilaria candidagilae sp. nov. Almeida, C. Delgado, Novais & S. Blanco. 2–19. Fragilaria candidagilae Almeida, C. Delgado, Novais & S. Blanco from Ribeira do Botão, (Mondego basin), 13/02/2012 (type population). 20–33. Fragilaria candidagilae sp. nov. Almeida, C. Delgado, Novais & S. Blanco from Brasfemes stream (Mondego basin), 13/02/2012. Scale bar = 10 μm.

FIGURES 34–39. SEM micrographs of Fragilaria candidagilae Almeida, C. Delgado, Novais & S. Blanco from Ribeira do Botão (Mondego basin), 13/02/2012. 34. Complete valve in external view with rimoportula on bottom apex. 35, 36. Complete valves in internal view with a rimoportula on bottom apex; 36. Arrow is pointing to open girdle band 37. Complete frustule in girdle view with arrow pointing to open girdle band. 38. Detail of the apex in external view, with the rimoportula clearly visible. 39. Detail of the apex of the frustule in external view, with the apical pore fields (APF). Scale bar = 10 μm..