Muelleria agnellus
Bahls 2014 Category: Symmetrical biraphid
BASIONYM: Muelleria agnellus Bahls 2014
LM scalebar = 10 µm = 80 pixels.
Observations
Contributor: Loren Bahls - November 2015
Length Range: 27-60 µm
Width Range: 9.5-12.3 µm
Striae in 10 µm: 13-18 at valve center, 20-24 at the apices
Description
Valves are lanceolate in smaller specimens to linear-lanceolate with slightly gibbous central margins in the largest specimens. Valve margins are convex and apices are broadly rounded. The raphe is straight and lies between two longitudinal canals. The axial area is narrow and the central area is small and elliptic. Proximal raphe ends are unilaterally deflected. Internally, a rectelevatum is present between the proximal raphe ends; distal raphe ends terminate in helictoglossae. Striae are distinctly curved and strongly radiate throughout. Striae are more distantly spaced in the valve center than in the rest of the valve. Areolae in the central striae appear larger and more distinct than areolae in more distal striae. Under SEM, external areolae openings are complex and highly variable in shape. Terminal raphe fissures are bifurcate and the two branches separate at a very wide angle of almost 180 degrees.
Original Description
Basionym: Muelleria agnellus
Author: Bahls 2014
Length Range: 26.9-59.6 µm
Width Range: 9.5-12.3 µm
Striae in 10 µm: 13-18 at valve center, 20-24 near the apices
Original Description
Valves are lanceolate to linear-lanceolate with slightly gibbous central margins in the largest specimens. Valve margins are convex and apices are broadly rounded. Valve length 26.9-59.6 μm; valve width 9.5-12.3 μm. The raphe is straight and filiform between two thickened longitudinal ribs, which occupy a narrow axial area. Proximal raphe ends are bent to the same side within a small elliptic central area. Striae are distinctly curved and strongly radiate throughout. Curved radiate striae meet short parallel striae that border the axial area at an obtuse angle, creating a criss-cross pattern near the valve apices. Areolae in the central striae appear larger and more distinct than areolae in more distal striae. Striae number 13-18 in 10 μm at valve center, 20-24 in 10 μm at the apices.
Original Images
Cite This Page:
Bahls, L. (2015). Muelleria agnellus. In Diatoms of the United States. Retrieved August 22, 2017, from http://westerndiatoms.colorado.edu/taxa/species/muelleria_agnellus
Species: Muelleria agnellus
Contributor: Loren Bahls
Reviewer: Bart Van de Vijver
Image Credit: Loren Bahls
- Valve margins slightly convex
- Valves >9.5 µm wide
- Striae radiate, distinctly curved
Valves are lanceolate, with slightly convex margins. Valves are wider than 9.5 µm. Striae are radiate, especially in the center of the valve, and distinctly curved. Proximal raphe ends are unilaterally deflected.
Compare
Muelleria terrestris has smaller valves (< 9 µm wide). Muelleria gibbula has smaller valves and a gibbous central margin. The valves of M. spauldingiae are elliptic while those of M. tetonensis are linear-elliptic with parallel margins. While similar in shape, valves of M. regigeorgiensis are smaller, and stria density is higher near the valve ends.
Muelleria gibbula
Muelleria spauldingiae
Muelleria tetonensis
Muelleria terrestris
(Petersen) Spaulding and Stoermer 1997
Muelleria regigeorgiensis
Van de Vijver and Spaulding 2010
Citations
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.
Spaulding, S.A. and Stoermer, E.F. (1997). Taxonomy and distribution of the genus Muelleria Frenguelli. Diatom Research 12: 95-113.
Spaulding, S.A., Kociolek, J.P. and Wong, D. (1999). A taxonomic and systematic revision of the genus Muelleria (Bacillariophyta). Phycologia 38: 314-341.
Van de Vijver, B., Mataloni, G., Stanish, L. and Spaulding, S.A. (2010). New and interesting species of the genus Muelleria (Bacillariophyta) from the Antarctic region and South Africa. Phycologia 49: 22-41. 10.2216/09-27.1
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID:
Autecology Discussion
Muelleria agnellus has been collected from mossy pools in the alpine zones of the Mission Mountains in Montana and the Wind River Mountains in Wyoming (photos below). These pools lie at elevations of 7,940 feet and 12,319 feet, respectively.
Images
Mossy pools on Horse Ridge in the Wind River Range, Fremont County, Wyoming: home of Muelleria agnellus.
Credit/Source: Beverly Boynton, Adventurers and Scientists for Conservation.
Closeup of mossy pool on Horse Ridge where Muelleria agnellus was collected.
Credit/Source: Beverly Boynton, Adventurers and Scientists for Conservation.
Mossy pool in the Mission Mountains, Missoula County, Montana: type locality of Muelleria agnellus.
Credit/Source: Bill Agnew, Adventurers and Scientists for Conservation