Patrick and Freese 1961 Category: Symmetrical biraphid
BASIONYM: Navicula walkeri Patrick and Freese 1961
Contributor: Paul Hamilton - December 2011
Length Range: 31.4-48.1 µm
Width Range: 8.0-9.6 µm
Striae in 10 µm: 10-11
Valves are linear to linear-lanceolate with narrowly rounded apices. Striae are weakly radiate at the center to parallel at the apices. The central area is small and asymmetrically rounded. The axial area is narrow and straight to weakly lanceolate. Striae on one, or both sides, of the central area are irregularly spaced. The raphe is lateral and straight. The distal fissures are scythe shaped and the proximal fissures curve, forming expanded ends. Areolae are lineate with a narrow interstria space. Girdle bands are not yet described.
Note that the original publication shows the name as Navicula walkeri Patrick and Freese. An errata sheet indicates that the name Navicula walkeri is replaced with Navicula perotii.
Basionym: Navicula walkeri
Author: Patrick and Freese 1961
Length Range: 30–74 µm
Width Range: 6–11 µm
Striae in 10 µm: 10–12
Navicula walkeri sp. nov. Pl. 2, Fig. 12
Valva lineari ad lineari-lanceolata, angustiore ad apices rotundatos. Area axiali angusta. Area media rotundata, asimili. Striis translineatis, radiatis leniter per partem maximam valvae, parallelis aut convenientibus leniter ad apices. Striis sepositis latius circum nodulem mediam. Striis, 10-12 in 10 µ. Longitudo 30-74 µ. Latitudo 6-11 µ.
Valve linear to linear-lanceolate, slightly narrower toward the rounded apices. Axial area narrow. Central area rounded, asymmetrical. Striae cross-lineate, slightly radiate throughout most of the valve, at the apices parallel or very slightly convergent. Striae more widely spaced about the central nodule. Striae 10-12 in 10 µ except at the central area. Length, 30-74 µ. Breadth, 6-11 µ.
This species resembles N. cincta. (Ehr.) Rails var. cincta in the shape of the valve, shape of the axial area, and the more distantly placed striae about the central area. It differs in the angle of the striae which are parallel to slightly convergent at the ends. The striae are also coarser throughout most of the valve. The striae about the central area are regular. This species is also characterized by the slightly asymmetrical central area. Occurrence in collection fairly numerous.
This species is named in honor of E. Perot Walker, who wrote the Latin descriptions of new taxa.
Specimen illustrated.—Station 72 (A-G.C. 8188A). Holotype.
Type locality.—Alaska, Sec. Jud. Div., Saltwater Lake, Pt. Barrow Camp. Coll. L. R. Freese, 14 July 1951.
Distribution.—GEOGRAPHICAL—In addition to the type locality, found also at Station 73, Coll. L. R. Freese, 14 July 1951 (A-G.C. 8189A). ECOLOGICAL-Fresh to brackish water. Holotype from algal scum on gravel-bottom pool. pH, 7.8; temp., 6° C. Other specimens from moss squeezings in nearby pool, but both close to edge of Saltwater Lake. pH, 7.5; temp., 5° C.
Patrick, R.M. and Freese, L.R. (1961). Diatoms (Bacillariophyceae) from Northern Alaska. Proceedings of the Academy of Natural Sciences of Philadelphia 112(6):129-293.