Bahls 2014 Category: Asymmetrical biraphid
BASIONYM: Cymbopleura maggieae Bahls 2014
REPORTED AS: Cymbopleura naviculiformis var. laticapitata (Krammer 2003, p. 57, plate 79, figs 1-12)
Contributor: Loren Bahls - September 2015
Length Range: 34-46 µm
Width Range: 7.9-9.6 µm
Striae in 10 µm: 13-16 (dorsal), 15-18 (ventral), more widely spaced at valve center and closer together at the ends
Valves are lanceolate and somewhat dorsiventral, with broadly subrostrate to subcapitate apices. Dorsal margins are moderately convex; ventral margins are weakly convex to almost straight. The axial area, located near the valve mid-line, widens gradually to merge with a large, rounded central area. The central area is three-fifths to three-quarters the valve width. The raphe is lateral, becoming filiform to reverse-lateral at the proximal ends, which are weakly expanded and deflected toward the ventral margin. Terminal raphe fissures are deflected dorsally. Striae are radiate and finely punctate. Areolae are difficult to resolve in LM.
This taxon is part of a holarctic species complex that includes C. linearis, C. fluminea, C. naviculiformis and C. sublanceolata. Krammer (2003) treats it as a variety of C. naviculiformis. It was elevated to the rank of species (Bahls 2014) based on recognition of it as being morphologically distinct from C. naviculiformis, as well as from other species in the complex.
Basionym: Cymbopleura maggieae
Author: Bahls 2014
Length Range: 33.5-46.4 µm
Width Range: 8.1-9.6 µm
Striae in 10 µm: 13-16 dorsal, 15-18 ventral
Description.—Valves are lanceolate and dorsiventral with rostrate to subrostrate apices. Dorsal margins are moderately arched, ventral margins are weakly convex to almost flat. Valve length 33.5-46.4 μm; valve width 8.1-9.6 μm. Length/width ratio is 3.9-5.0. Axial area, just below the apical axis, widens gradually to merge with a very large rounded central area. Central area is three-fifths to threequarters of the valve width. The raphe is lateral, becoming filiform to reverse-lateral at the proximal ends, which are deflected toward the ventral margin and tipped with weakly expanded pores. Terminal raphe fissures are deflected dorsally. Striae are radiate and very finely punctate, 13-16 in 10 μm (dorsal), 15-18 in 10 μm (ventral). A few striae are more widely spaced at valve center and more closely spaced near the apices.
Bahls, L. (2014). New diatoms from the American West–A tribute to citizen science. Proceedings of the Academy of Natural Sciences of Philadelphia 163: 61-84.
Krammer, K. (2003). Cymbopleura, Delicata, Navicymbula, Gomphocymbellopsis, Afrocymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 4: 1-530.
Cymbopleura maggieae has been recorded from four ponds, small lakes, and wet meadows in Montana, Oregon and Washington. Krammer (2003) reports this taxon (as C. naviculiformis var. laticapitata) from a “moory bog” in Swedish Lapland.
Loudon Lake, Okanogan County, Washington: home of Cymbopleura maggieae.
Credit/Source: Ryan Davis, Adventurers and Scientists for Conservation