Cymbella affinis var. angusta (Krammer) W.Silva, 2015

Silva, Weliton Jose da, Jahn, Regine, Ludwig, Thelma Alvim Veiga, Hinz, Friedel & Menezes, Mariangela, 2015, Typification and taxonomic status re-evaluation of 15 taxon names within the species complex Cymbella affinis / tumidula / turgidula (Cymbellaceae, Bacillariophyta), PhytoKeys 53, pp. 1-25 : 5

Cymbella affinis var. angusta (Krammer) W.Silva comb. nov. Figs 29-35

Basionym.

Cymbella excisa var. angusta Krammer, Diatoms Europe 3: 159, Figs 9: 8-13, 2002.

Holotype.

Preparation 752 IOK, in the Alfred-Wegener-Institut für Polar- und Meeresforschung (BRM), Bremerhaven, Germany.

Lectotype

(designated here). An individual on preparation 752 IOK, in the Alfred-Wegener-Institut für Polar- und Meeresforschung (BRM), Bremerhaven, Germany, represented by Fig. 29 .

Type locality.

Croatia, watercourse near Lake Gavanovac, Plitvice.

Valves dorsiventral, dorsal margin broadly convex, ventral margin straight, usually with excision in middle portion; ends not protracted to slightly protracted, rounded, subrostrate or subcapitate; length 20.5-35.0 µm, breadth 6.0-8.5 µm, L/B ratio 3.2-4.6; axial area linear-arched, indistinct central area; striae 9-15 in 10 µm, becoming 11-18 towards ends, one isolated pore at end of central striae of ventral side; 19-29 punctae in 10 µm.

Remarks.

The material recorded here presented slight differences in the valve metrics compared to Krammer’s (2002, p. 28) characterization from the same preparation; differences included valve length (20.5-35.0 vs. 17.0-34.0 µm), breadth (6.0-8.4 vs. 6.7-8.2 µm), striae (9-15 vs. 11-14 in 10 µm) and number of punctae (19-29 vs. 25-28 in 10 µm).

Similar to Cymbella affinis var. neoprocera , specimens designated by Krammer (2002), i.e., the preparation 752 IOK (BRM), were found to belong to more than one taxon. Therefore we designated a lectotype for this taxon as established in Art. 9.11 of the ICN ( McNeill et al. 2012).

Figures

Figures 29 - 42. Cymbella affinis species complex 29 - 35 Cymbella affinis var. angusta (Krammer) W. Silva, specimens from Croatia in preparation 752 IOK, holotype 29 Lectotype, designated here 36 - 42 Cymbella affinis var. subcapitata (Krammer) W. Silva, specimens from Hungary in preparation 717 IOK, holotype 39 Lectotype, designated here. Scale bar: 10 µm.