Stauroneis thompsonii Bahls, 2012

Bahls, Loren, 2012, Five new species of Stauroneis (Bacillariophyta, Stauroneidaceae) from the northern Rocky Mountains, USA, Phytotaxa 67 (1), pp. 1-8 : 4-6

Stauroneis thompsonii Bahls , sp. nov. ( Figs 22–24 )

Type: — USA. Montana: Upper Wolverine Lake ( Fig. 25 ), Ten Lakes Scenic Area , Kootenai National Forest , Lincoln County, 48.9705 o N, 114.9221 o W, 1890 m elevation, collected from rocks and sediment by Loren Bahls, 9 September 1990. MDC sample 108601 ; holotype slide MDC P3-3-1, Figs 22–24 .

Valves lanceolate with rounded, unprotracted apices. A deep pseudoseptum occupies each apex ( Fig. 24 ). Valve length 88–105 µm; valve width 16.3–17.5 µm. Raphe lateral with straight proximal ends, slightly inflated. Distal raphe ends hooked to same side. Axial area narrowly lanceolate, widens gradually towards central area. Central stauros nearly rectangular and placed somewhat diagonally to apical axis. Striae radiate throughout, 17–18 in 10µm. Areolae in striae 12–15 in 10 µm.

Etymology:— Stauroneis thompsonii is named for David Thompson (1770–1857), an early 19 th Century Montana explorer and cartographer ( Jenish 2003).

Observations: — Stauroneis thompsonii was reported by Bahls (2010: 61) as S. aff. catharinae Van de Vijver & Lange-Bertalot (2004: 27) . However, it has significantly wider valves and lower stria and areola densities than S. catharinae . It is known only from the type locality, a small lake in the Galton Range in northwest Montana ( Fig. 25 ).

Figures

FIGURE 25: Wolverine Lakes in the Galton Range, northwest Montana. Upper Wolverine Lake (foreground) is the type locality of Stauroneis thompsonii and typical of habitats for Stauroneis species in the northern Rocky Mountains. Photo by the author.

FIGURES 9–24: Stauroneis sacajaweae, S. spauldingiae, and S. thompsonii. Figs 9–15: Stauroneis sacajaweae. Figs 9, 11–15: Type locality. Fig. 10: Haystack Seep, Going-To-The-Sun Road, Glacier National Park, Montana. Figs 16–21: Stauroneis spauldingiae. Figs 16–18, 20, 21: Copper Lake, Shoshone County, Idaho (type locality). Fig. 19: Lily Lake, Lemhi County, Idaho. Figs 22–24: Stauroneis thompsonii from the type locality.