Navicula supleeorum Bahls, 2013

Bahls, Loren, 2013, New diatoms (Bacillariophyta) from western North America, Phytotaxa 82 (1), pp. 7-28 : 19

Navicula supleeorum Bahls , sp. nov. ( Figs 69–75 )

Valves lanceolate in larger specimens to elliptic-lanceolate in smaller specimens. Valve length 23–32 µm; valve width 6.1–7.0 µm. Apices acutely rounded, not protracted in larger specimens, weakly protracted in smaller specimens. Axial area narrow, barely wider than the raphe, widening into a small elliptic central area. Raphe straight and weakly lateral, becoming filiform near the proximal and distal ends. External proximal raphe ends dilated. Striae radiate, becoming parallel then weakly convergent at the apices, 12–14 in 10 µm. Alternate short-long-short striae typical in the central area. Areolae 30–32 in 10 µm.

Holotype:— USA, Montana: Valley County, Rock Creek , 48.5903 o N, 107.0011 o W, elevation 680 m, coll. Montana DEQ, 6 September 2004. MDC sample 339511; holotype slide MDC 108-22 ( Figs 69–75 ) (circled holotype specimen in Fig. 72 ). MONTU!

Isotype: —MDC slide 28-59 (MONTU!).

Etymology:—This species is named in honor of Rosie Sada de Suplee and Michael Suplee, Montana Department of Environmental Quality.

Observations:— Navicula supleeorum has a lower stria density than N. cryptotenella Lange-Bertalot in Krammer & Lange-Bertalot (1985: 62) (14–16 in 10 µm) and N. wygaschii Lange-Bertalot (2001: 81) (16–18 in 10 µm). It also has a lower areolae density than N. cryptotenella (38 in 10 µm), N. wygaschii (36–38 in 10 µm), and N. mediocostata Reichardt (1988: 241) (35 in 10 µm).

Distribution and Ecology: — Navicula supleeorum is known only from the type locality. It probably has been mistaken for and lumped with N. cryptotenella in biological surveys. On the date the type sample was collected, pH in Rock Creek measured 8.30 and specific conductance measured 1402 µS/cm.

Figures

FIGURES 69–84: Navicula supleeorum, Navicula trilatera. Figs 69–75: Navicula supleeorum from Rock Creek, Valley County, Montana (type locality). Fig. 72: Holotype specimen. Figs 76–84: Navicula trilatera from Blakiston Beaver Pond A, Waterton Lakes National Park, Alberta (type locality). Figs 76–82: LM images. Fig. 78: Holotype specimen. Figs 83, 84: SEM images. Fig. 83: External valve view showing lineate striae and distal raphe ends hooked toward the same (secondary) side of the valve. Fig. 84: Internal valve view showing thickened raphe sternum and distal raphe ends terminating in helictoglossae. Scale bars: Figs 69–82: 10 µm; Figs 83, 84: 5 µm.