Navicula teletskoyensis Chudaev, 2019

Chudaev, Dmitry A., 2019, New species of the genus Navicula Bory (Bacillariophyceae, Naviculaceae) from Lake Teletskoye, Phytotaxa 404 (4), pp. 163-169 : 164-165

Navicula teletskoyensis Chudaev , sp. nov. ( Figs 1–24 )

( N. pseudolanceolata Lange-Bertalot sensu Lange-Bertalot 2001 , fig. 10: 22 nec alii)

Light microscopy ( Figs 1–18 ). Valves lanceolate with slightly protracted very acutely rounded apices, length 36.2– 64.1 μm, width 9.4–11.2 μm. Axial area moderately narrow, linear; central area transversely expanded, more or less elliptical, occupying about 1/2 of valve width, sometimes with irregular borders due to unequal shortening of central striae. Striae radiate at the valve centre, becoming convergent near the poles, 8.7–10.0/10 μm. Areolae coarse, well discernible in light microscope, 20–22/10 μm. Raphe lateral, terminal fissures barely visible in light microscope, curved to the secondary valve side; central pores drop-like, straight (in DIC optics appear deflected to the secondary valve side).

SEM, external valve surface ( Figs 19–21 ). Areolae lineolate, apically elongated; areolae openings flush with valve surface, as a result no longitudinal furrows are formed. Raphe-sternum very sligthly elevated above the rest of valve surface. Central raphe endings widened, drop shaped, straight. Terminal fissures very slightly bent to the secondary valve side, finally abruptly curving at the valve mantle.

SEM, internal valve surface ( Figs 22–24 ). Striae lie in slight transapical depressions. Raphe slit uninterrupted at the centre. Terminal raphe endings are well developed, straight helictoglossae. Accessory rib almost not developed. Three small apical areolae are located at each valve apex.

Type: — RUSSIA. Altai Republic: Lake Teletskoye, Karagay hole, 51º21’14” N, 87º50’49” E, periphyton, O. V. Anissimova, 6 August 1994 (Holotype: slide 692s1, diatom collection of the Department of Mycology and Algology, M. V. Lomonosov MSU, specimen here depicted in Fig. 4 . Isotype: LE! slide 692s2, Komarov Botanical Institute, St. Petersburg, Russia).

Etymology: —The specific epithet is given according to the name of Lake Teletskoye, where the species was found.

Distribution and ecology: —The species is so far precisely known only from Lake Teletskoe, however may be more widely distributed because of presence of the taxon in published micrographs ( Lange-Bertalot 2001, fig. 10: 22, without indication of geographic origin, see below). Physico-chemical parameters of Lake Teletskoye according to the literature data are following: pH 7.7–7.9, mineralization 62.6–82.0 mg/dm 3, permanganate oxidizability 2.1–4.8 mgO/ dm 3, BOD 5 0.1–6.4 mg O 2 /dm 3 ( Dolmatova 2008); ranges of biogens concentration are <0.005 –0.210 mg /dm 3 for NH 4 +, 0.001 –0.072 mg /dm 3 for PO 4 3-, 0.53–3.16 mg /dm 3 for NO 3 - and 2.24–4.71 mg /dm 3 for Si ( Mitrofanova & Tretyakova 2013).

Figures

FIGURE 1–18. Navicula teletskoyensis sp. nov., light microscopy, type material (slide 692s1), fig. 4 represents the holotype specimen. 1–9. DIC optics. 10–18. Bright field optics. Scale bar: 10 μm.

FIGURE 19–24. Navicula teletskoyensis sp. nov., SEM, type material. 19–21. External valve views. 22–24. Internal valve views. 19, 22. Whole valve. 20, 23. Valve centre. 21, 24. Valve apex. Scale bars: 5 μm (Figs 19, 22), 1 μm (Figs 20–21, 23–24).