Neidium inconstans Sovereign (1963: 351

Bahls, Loren, 2013, New diatoms (Bacillariophyta) from western North America, Phytotaxa 82 (1), pp. 7-28 : 18

Neidium inconstans Sovereign (1963: 351 , fig. 13) ( Figs 52–55 )

Type: — USA, Washington: Adams County, Finnel Lake , elev. 550 m, CAS accession no. 600683, CAS holotype slide no. 205090, CAS isotype slide no. 187016 ( Kociolek et al. 1999) .

Vouchers:— CANADA, Alberta: Waterton Lakes National Park, Indian Springs Pond , 49.1297 o N, 113.8731 o W, elev. 1340 m, coll. B. Johnston, 5 June 2009. MDC sample 454301; MDC slides 124-1( Figs 52- 55 ), 40-26. MONTU !

Observations:—Valves lanceolate to linear-lanceolate with subrostrate to subcapitate apices and weakly triundulate margins. Valve length 38–56 µm; valve width 9.9–13.0 µm. A longitudinal line evident along each margin. Axial area narrow; central area very wide, rectangular but distinctly asymmetric and oriented diagonally to the apical axis. Short striae present in central area at valve margins. Raphe weakly lateral, becoming filiform near the proximal ends. Proximal ends hooked sharply in opposite directions. Striae slightly radiate near the central area, parallel to weakly convergent near the apices, 14–15 in 10 µm. Areolae 20–24 in 10 µm.

The Alberta population differs from the type population in its somewhat smaller valves and lack of capitate apices, and perhaps represents the small end of this taxon. Neidium inconstans has a wider central area and a lower stria density than Neidium fogedii stat. nov., nom nov. ( Figs 60–65 ).

Distribution and Ecology: —The occurrence in Alberta represents a significant range extention for this species. Until now it had been known only from the type locality. The pond in Alberta is alkaline (pH 8.1) with intermediate specific conductance (302 µS/cm).

Figures

FIGURES 52–68: Neidium inconstans, Neidium bobmarshallensis, Neidium fogedii, Neidium undulatum. Figs 52–55: Neidium inconstans from Indian Springs Pond, Waterton Lakes National Park, Alberta. Figs 56–59: Neidium bobmarshallensis. Fig. 56: Logging Lake, Glacier National Park, Montana. Figs 57, 59: Dean lake, Bob Marshall Wilderness, Montana (type locality). Fig. 57: Holotype specimen. Fig. 58: Upper Trilobite Lake, Bob Marshall Wilderness, Montana. Figs 60–65: Neidium fogedii from Mexican Cut Upper Pond No. 56, Gunnison County, Colorado. Figs 66–68: Neidium undulatum from Grassy (Axolotl) Lake, Madison County, Montana. Scale bars: 10 µm.