Brevilinea kevei Ács et Ector, 2016

Ács, Éva, Wetzel, Carlos E., Hlúbiková, Dasa, Grigorszky, István, Trábert, Zsuzsa & Ector, Luc, 2016, Morphology and distribution of Brevilinea kevei sp. nov. (Bacillariophyceae), a new diatom from Europe, Phytotaxa 284 (1), pp. 24-30 : 25-27

Brevilinea kevei Ács et Ector sp. nov. ( Figs 1 −30)

Description: In LM ( Figs 1−20 ), the valves are rhombic-elliptic to oval with rounded apices. The striation is irresolvable. Practically only the raphe, the central nodule and helictoglossae are visible. Valve length 3.9–5.5 μm (mean: 4.9 μm, SD: 0.33, n=26), valve width 1.8–2.5 μm (mean: 2.1 μm, SD: 0.16, n=26).

Ultrastructure based on SEM micrographs ( Figs 21 –28): Striae are radiate and composed of single rows of areolae. Stria density 50 in 10 μm, composed by 2–6 areolae/stria. Virgae are raised clearly separating striae and areolae (Fig. 25). The thickened virgae continue on the mantle ( Fig. 22 ). Areolae are closed by hymenes, and are square in external view (Fig. 23) and round in internal view (Fig. 24). The external raphe fissure is slightly curved, the raphe-sternum is prominent (Fig. 26). The distal ends of the raphe are drop-shaped and the central raphe endings are slightly deflected to the same valve side ( Fig. 22 ). The proximal ends of the raphe are spaced ( Figs 21–22 , 27). Internally, the raphe fissures are straight, terminating in small helictoglossae near the valve poles (Figs 24, 28). The valve margin is thickened ( Fig. 22 ). TEM micrographs show the radiate striae composed of single rows; the large, square shaped areolae are clearly visible (Figs 29–30).

Holotype: Fig. 25 designated here. Type material: GO-14/11, deposited at the Centre for Ecological Research, Danube Research Institute, Budapest, Hungary, epiphyton, collected by K. Nagy on 16/08/2011. BP2260 deposited at the Hungarian Natural History Museum , Budapest, Hungary.

Type locality: Kanyari Holt-Tisza, Hungary (47.489822°N, 20.449911°E).

Isotypes: Figs 26–30 designed here.

Paratypes: Figs 21 –24 designed here.

Etymology: The name is chosen in honour of the famous Hungarian algologist Prof. Dr. Keve T. Kiss. Investigation of type material of Fallacia indifferens (Hustedt) D.G. Mann

Holotype: Hasbruch. Moss üb. Wasser b. d. Hütte. 1. Forst Delmenorst in Oldenburg.

In LM ( Figs 32−41 ), the valves are rhombic-elliptic to oval with rounded apices. These characteristics were also drawn by Hustedt ( Fig. 31 ; Hustedt 1942, figs 27–30). Practically only the raphe is visible. Valve length 6.5–8.0 μm, valve width 2.5–3.2 μm.

Ultrastructure based on SEM micrographs ( Figs 42–45 ): Striae are radiate and composed of two elongated areolae ( Figs 42, 44 ), internally covered by hymenes ( Figs 43, 45 ). Stria density 34–45 in 10 μm. In external view, lanceolate conopeum covers of approximately half valvar face ( Figs 42, 44 ). The raphe is filiform, almost straight. The raphe-sternum is not prominent. Externally the distal raphe endings are deflected to the primary valve side and elongated onto the valve mantle ( Figs 42, 44 ). Central raphe endings are internally close to each other ( Fig. 43 ) and externally slightly deflected to the same valve side ( Figs 42, 44 ). Internally the raphe fissures are straight, terminating in small helictoglossae ( Figs 43, 45 ).

Distribution and ecology of Brevilinea kevei

The new taxon occurs in eutrophic waters with high electrolyte content. The water pH was 7.8 at the time of sampling. When first sampled this species was recorded from an abandoned dredge pond near Bulolo, Papua New Guinea, which is alkaline water with high conductivity, however it was misidentified as Navicula saprophila Lange-Bertalot & Bonik (1976: 312) ( Vyverman 1991: fig. 115B, outside view in SEM). New locations of B. kevei were recorded only in Europe ( Fig. 46 ). In addition to the type locality in Hungary, we have found it in several places in France: Layon River at Saint-Lambert-du-Lattay, Region Pays de la Loire, August 2003, its relative abundance was 3.7 %; Sanguèze River at Le Pallet, Region Pays de la Loire, June 2011, with relative abundance of 4.2 %; Canal de Berry at Épineuil-le-Fleuriel, Cher Basin, Region Centre-Val de Loire, August 2011, with relative abundance of 4 %.

Figures

FIGURE 46. Distribution of the Brevilinea species. Black circle: type locality of B. pocosinensis. Black stars: the records of B. kevei. White star: type locality of B. kevei.

FIGURES 1–22. Brevilinea kevei sp. nov. LM: (1–10) from the Canal de Berry, France, (11–20) from the Kanyari Holt-Tisza, Hungary. Scale bar: 10 μm. FIGURES 21–30. Brevilinea kevei sp. nov. SEM: (21–24) from the Canal de Berry, France, (25–31) from the Kanyari Holt-Tisza, Hungary, SEM: 21–23, 25–27 external view. SEM: 24, 28 internal view; TEM: 29–30. Scale bars: 2 μm (21–27, 29), and 1 μm (28, 30). Holotype: 25; isotypes: 26–30; paratypes: 21–24.

FIGURES 31–45. Fallacia indifferens. 31: Hustedt’s (1942) original drawing with his numbers (27–30). 32–41: LM images of the type material. Scale bar: 10 μm. SEM images from the type material. 42, 44 external view, 43, 45 internal view. Scale bars: 2 μm (42) and 3 μm (43–45).