Micrasterias foliacea var. elongata (W.B. Turner) Willi Krieger, 1939

Levanets, Anatoliy & Janse van Vuuren, Sanet, 2023, Morphology, taxonomy, biogeography and ecology of Micrasterias foliacea Bailey ex Ralfs (Desmidiales, Zygnematophyceae), PhytoKeys 226, pp. 33-51 : 33

2. Micrasterias foliacea var. elongata (W.B. Turner) Willi Krieger, 1939

Micrasterias foliacea var. elongata (W.B. Turner) Willi Krieger, 1939. “Rabenhorst’s Kryptogamen-Flora von Deutschland", “Österreich und der Schweiz", 2 Aufl., 13 (Abt.1, Teil 2): 77.

Synonyms.

M. foliacea Bailey ex Ralfs var. β Wallich, 1860. "Annals and Magazine of Natural History" Series 3, 5: 280, tab. XIV, figs 1-4; M. foliacea Bailey ex Ralfs f. β elongata Turner, 1892. "Aquae Dulcis Indiae Orientalis": 94.

This variety was originally described by Wallich (1860) as "var. β”. A later study by Turner (1892) revealed the same alga, but he described it as "forma β elongata ". In his monograph, Krieger (1939) indicated the same algal species as "var. Micrasterias elongata elongata Turner".

Morphology.

The prominent feature of M. foliacea var. elongata is the largely developed, triangular terminal lobe, with an outward directed base, emarginate at its angles and centre and furnished with two short stout teeth placed obliquely to each other (comparable to that of M. baileyi ). The central emargination of this lobe is deep and rectangular and the entire lobe projects very slightly beyond the apices of the lateral lobes. The margins of the filament are parallel and direct, the fronds tabular, and divided by a very deep constriction into two dichotomously incised segments, the ultimate subdivisions of which are emarginate. In the Bengal variety, the teeth-like projections next to the terminal lobe are acutely angular, instead of being rounded and, as in the case of Onychonema , the projecting processes, by which cohesion is either secured or increased, overlap each other alternately in adjacent fronds. The cell length is 85-90 μm, width 70-75 μm, width of isthmus 11-13 μm, width of apex 32 μm, width of polar lobes 15 μm ( Wallich 1860; Turner 1892).

Distribution.

This variety seems to be endemic to southeastern tropical Asia (Lower Bengal, India; Fig. 2 and Suppl. material 2), where it was found in the 1800's by Wallich ( Wallich 1860). A single record of this variety from Sierra Leone ( Woodhead and Tweed 1958; Suppl. material 2) is doubtful, because descriptions and illustrations of the cell morphology, as well as information about the sampling site, are absent.

Habitat and ecology.

No information is available in the literature about the habitats or ecology of this variety.

Figures

Figure 2. Worldwide distribution of different varieties of Micrasterias foliacea.