Cymbella cosleyi Bahls, 2013

Bahls, Loren, 2013, New diatoms (Bacillariophyta) from western North America, Phytotaxa 82 (1), pp. 7-28 : 10-11

Cymbella cosleyi Bahls , sp. nov. ( Figs 13–20 )

Valves distinctly dorsiventral with subrostrate or simply rounded apices. Dorsal margin strongly arched, ventral margin nearly flat or weakly concave and slightly gibbous in the middle. Valve length 20–31 µm; valve width 5.5–7.1 µm. Axial area narrow, central area small and asymmetric, rounded on the dorsal side and flat on the ventral side. Raphe lateral, becoming reverse-lateral near the proximal pores, which are slightly expanded. Proximal raphe ends deflected ventrally, then recurved slightly toward the dorsal margin. Distal raphe ends deflected dorsally. Striae slightly radiate near valve middle, becoming more strongly radiate near apices, 10–12 at valve center, 14–16 near apices. Two indistinct stigmata at ends of middle ventral striae. Areolae easily resolved under LM, 28–30 in 10 µm.

Holotype: — USA, Montana: Flathead County, Glacier National Park, Bowman Lake , 48.8356 o N, 114.1967 o W, elev. 1228 m, coll. L. Bahls, 1 August 2007. MDC sample 404801; holotype slide MDC 117-31 ( Figs 14, 16–20 ) (circled holotype specimen in Fig. 16 ). MONTU!

Isotypes: —MDC slide 38-32 ( MONTU!); ANSP GC 64931.

Paratypes: — USA, Montana: Glacier County, Glacier National Park, Belly River , 48.9681 o N, 113.6822 o W, elev. 1392 m, coll. S. Nadeau, 16 August 1980. MDC sample 076101; MDC slide B1-1-1 ( Fig. 13 ). MONTU !— USA, Montana: Flathead County, North Fork Flathead River , 48.4933 o N, 114.1253 o W, elev. 975 m, coll. R . Greene , 22 March 1979. MDC sample 050803; MDC slide P2-8-14 ( Fig. 15 ). MONTU !— CANADA, Alberta: Waterton Lakes National Park, Cameron Lake , 49.0000 o N, 114.0578 o W, elev. 1660 m, coll. L. Bahls, 24 July 2009. MDC sample 452001; MDC slides 39-88, 123-59. MONTU !

Etymology:—This species is named after the legendary Joe Cosley, ranger turned outlaw in Glacier National Park's Belly River country ( McClung 1998).

Observations: —Under SEM in external valve view ( Fig. 19 ), ventrally deflected proximal raphe ends and dorsally deflected terminal raphe fissures are evident. Internally ( Fig. 20 ), the intermissio is arched and the distal raphe ends terminate in helictoglossae. Valves of Cymbella cosleyi have nearly flat ventral margins in contrast to the strongly concave ventral margins of Cymbella subarctica Krammer (2002: 103) and Cymbella cleve-eulerae Krammer (2002: 105) .

Distribution and Ecology: Cymbella cosleyi has been collected from four lakes and rivers in Glacier National Park, Montana and Waterton Lakes National Park, Alberta (holotype, paratypes). These waters have somewhat alkaline pH (7.80–8.54) and low specific conductance (92–209 µS/cm).

Genus: Cymbopleura (Krammer) Krammer 1999: 292

Figures

FIGURES 13–20: Cymbella cosleyi. Figs 13–18: LM images. Fig. 13: Belly River, Glacier National Park, Montana. Figs 14, 16–18: Bowman Lake, Glacier National Park, Montana (type locality). Fig. 16: Holotype specimen. Fig. 15: North Fork Flathead River, Glacier National Park, Montana. Figs 19, 20: SEM images (type locality). Fig. 19: External valve view showing proximal raphe ends deflected ventrally and distal raphe fissures deflected dorsally. Fig. 20: Internal valve view showing arched intermissio and distal raphe ends terminating in helictoglossae. Scale bars: Figs 13–18: 10 µm; Figs 19, 20: 5 µm.

FIGURES 1–12: Staurophora columbiana, Staurophora soodensis. Figs 1–6: Staurophora columbiana. Figs 1, 2, 3, 6: Kingsbury Lake, Chouteau County, Montana (type locality). Fig. 1: Holotype specimen. Figs 4, 5: Hailstone National Wildlife Refuge, Stillwater County, Montana. Fig. 4: Janus valve. Figs 7–12: Staurophora soodensis from White Lake, Sheridan County, Montana. Fig. 9: Girdle view. Scale bars: 10 µm.