Metzeltin and Lange-Bertalot 1998 Category: Symmetrical biraphid
BASIONYM: Stauroneis conspicua Metzeltin and Lange-Bertalot 1998
REPORTED AS: Stauroneis phoenicenteron Morphotype II (Lange-Bertalot and Metzeltin 1996) | Stauroneis italica (Lange-Bertalot et al. 2003) | Stauroneis phoenicenteron (Krammer and Lange-Bertalot 1986)
Contributor: Loren Bahls - December 2011
Length Range: 55-123 µm
Width Range: 14-24 µm
Striae in 10 µm: 14-20
Valves are lanceolate to elliptic-lanceolate with short, broadly rounded sub-rostrate to sub-capitate apices. The axial area is about three times wider than the raphe and nearly linear. The central area is a narrow rectangular stauros, expanding somewhat towards the valve margins. Short striae are sometimes present at the margins of the stauros. The raphe is lateral, becoming filiform near the proximal ends, which are nearly straight and slightly expanded. The striae are curved and radiate throughout, more so towards the valve ends. Striae are more widely spaced near the stauros along the valve margins. Areolae are coarse, 14-22 in 10 µm.
Although Stauroneis conspicua and S. italica are two species that have been recognized in Europe, these species appear to cover a continuous spectrum in size and morphology in North American material. That is, in the western US, the two species cannot be distinguished based on size or shape. As a result, we recognize the name with priority, S. conspicua, and apply to it a wider size range than stated in the original description of S. conspicua.
Basionym: Stauroneis conspicua
Author: Metzeltin and Lange-Bertalot 1998
Length Range: 90-120 µm
Width Range: 21-25 µm
Striae in 10 µm: 14-16
Valvae late lanceolatae ad elliptico-lanceolatas apicibus plus minusve breviter protractis, rostratis vel subrostratis et late rotundatis, 90-120 µm longae, 21-25 µm latae. Fissurae raphis satis laterales et rectissime in poros centrales parvos pertinentes. Area axialis modice lata, area centralis fasciam modice latam (stauros in forma vittae) formans usque ad margines. Striae transapicales proxime modice, distaliter magis radiantes omnino, 14-16 in 10 µm. Puncta 14-17 in 10 µm. Pseudosepta absunt. A St. phoenicenteron et St. gracilis satis differt.
Bahls, L. (2010). Stauroneis in the Northern Rockies: 50 species of Stauroneis sensu stricto from western Montana, northern Idaho, northeastern Washington and southwestern Alberta, including 16 species described as new. Northwest Diatoms, Volume 4. The Montana Diatom Collection, Helena, 172 pp.
Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Süsswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.
Lange-Bertalot, H. and Metzeltin, D. (1996). Indicators of oligotrophy - 800 taxa representative of three ecologically distinct lake types, Carbonate buffered - Oligodystrophic - Weakly buffered soft water. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 2. Ecology, Diversity, Taxonomy. Koeltz Scientific Books. Königstein, Germany, 2:390 pp.
Lange-Bertalot, H., Cavacini, P., Tagliaventi, N. and Alfinito, S. (2003). Diatoms of Sardinia: Rare and 76 new species in rock pools and other ephemeral waters. Iconographia Diatomologica 12, 438 pp.
Metzeltin, D. and Lange-Bertalot, H. (1998). Tropical diatoms of South America I: About 700 predominantly rarely known or new taxa representative of the neotropical flora. In: Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 5. Diversity-Taxonomy-Geobotany. Koeltz Scientific Books. Königstein, Germany, 5:695 pp.
Stauroneis conspicua is widely distributed in the Northern Rockies in small lakes and ponds with alkaline waters of moderate conductivity. The pH of these waters ranges from 6.8 to 9.1 (mean pH = 8.0) and specific conductance ranges from 10 to 1270 µS/cm (mean SC = 172 µS/cm). Lange-Bertalot et al. (2003) report that S. conspicua is “a rare but possibly cosmopolitan taxon”. The type locality is a waterfall in the Yucatan, Central America. It has also been recorded from an oligo-dystrophic lake in Finland (Lange-Bertalot & Metzeltin 1996). Of all the common Stauroneis species in the Northern Rockies, S. conspicua prefers the highest mean pH and specific conductance levels.
Lake Josephine near Billings, Yellowstone County, Montana: home of Stauroneis conspicua.
Credit/Source: Loren Bahls