Cyclotella idahica Khursevich & Kociolek, 2013

Kociolek, J. P. & Khursevich, G. K., 2013, Morphology of some fossil lacustrine centric species from the western United States assigned to the genus Cyclotella (Bacillariophyta), including four described as new, Phytotaxa 127 (1), pp. 81-99 : 83-84

publication ID

https://doi.org/ 10.11646/phytotaxa.127.1.11

persistent identifier

https://treatment.plazi.org/id/03905B22-FFEA-FFC7-D0D8-AEBF5582FDC2

treatment provided by

Felipe

scientific name

Cyclotella idahica Khursevich & Kociolek
status

sp. nov.

Cyclotella idahica Khursevich & Kociolek , sp. nov. ( Figures 1–9 View FIGURES 1–5 View FIGURES 6–9 )

Type:— USA. Oregon: Christmas Valley , Fort Rock, 44° 10' N, 121° 48' W, OD Section 7.9 m (see Colbath & Steele 1982), diatomite, collected summer 1981 (Circled specimen ( Fig. 2 View FIGURES 1–5 ) on Slide 019002, material Kociolek Collection 0502 ( COLO!), holotype, designated here; duplicate slide of COLO 019002 About COLO deposited in Khursevich Collection, GoogleMaps Minsk, Belarus, isotype, designated here) .

Additional material examined: — Idaho, Payette County, north bank of Willow Creek , 20 km NE on Willow Road from its intersection with Idaho highway 52, near center sec. 4, T. 8N., R. 2W., coll. S. Van Landingham. Diatomite is from Poison Creek Formation in the lower portion of Idaho Group, age approximately 11 to 12 mya.

Description:—Valve outline oval-elliptical, sometimes nearly circular, with several girdle bands. Dimensions of the major axis 8.0–48.0 µm, minor axis 6.5–46.0 µm. Valve surface is divided into two distinct zones. Central zone oval to elongate, transversely undulate, with irregularly arranged areolae, becoming more or less radiate, 7–10/ 10 µm in large specimens only. Areolae with internal domed velum and external foramina. Fultoportulae on the valve face have two to four satellite pores, but those with three satellite pores are located mainly in the concave part of the valve face internally. Fultoportulae with small aperatures externally. External valve face is often covered with bumps. Marginal zone extends from 1/3 to 1/2 of the valve radius, and consists of alveolate striae in fascicles, 7–10/ 10 µm, separated by hyaline interfascicles. Each fascicle consists of 3–4 parallel or slightly wavy rows of small puncta. Puncta number 40–60 in 10 µm measured radially, in small specimens. In large specimens, 5–6 puncta at the margin become bi- or triseriate on the valve face. Striae fascicles are all of the same length. A ring of marginal chambers can be observed internally. Adjacent chambers are divided by thicker costae. Each chamber encompasses mostly 2 or 3 alveolar openings separated by thinner costae bearing marginal fultoportulae with 3 satellite pores, 4–6/ 10 µm. Externally marginal fultoportulae are represented by short tubes, which are often broken. A single rimoportula with a slit oriented radially or subradially occurs in association with a thinner costa. The rimoportula has a small external opening. Spines are irregular in number, being located on the interfascicles at the margin. Granules occur along the mantle edge.

Cyclotella idahica differs from C. jonesii McLaughlin (1992: 96 , figs 1–11; see Figs 70–77 View FIGURES 70–71 View FIGURES 72–77 herein) by the smaller size of the valves, circular or oval valve shape, consistently having valve face fultoportulae, and having more pronounced bumps and granules on the valve face. Despite these differences, the two species share many features and appear to have close phylogenetic affinities.

COLO

University of Colorado Herbarium

T

Tavera, Department of Geology and Geophysics

R

Departamento de Geologia, Universidad de Chile

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