Eunotia luna var. aequalis f. major Frenguelli

Guerrero, José M. & Vouilloud, Amelia A., 2022, Taxonomic revision of Eunotia luna var. aequalis f. paucistriata Frenguelli and E. luna var. aequalis f. major Frenguelli: analysis of type material, lectotypification and current taxonomic status, Phytotaxa 561 (3), pp. 291-300 : 295

publication ID

https://doi.org/ 10.11646/phytotaxa.561.3.5

DOI

https://doi.org/10.5281/zenodo.7075177

persistent identifier

https://treatment.plazi.org/id/2E1487FC-F372-EA3D-FF01-FAE5FD836CBC

treatment provided by

Plazi

scientific name

Eunotia luna var. aequalis f. major Frenguelli
status

 

Eunotia luna var. aequalis f. major Frenguelli ( Figs 27–36 View FIGURES 27–36 )

According to the original description ( Frenguelli 1933), E. luna var. aequalis f. major differs from E. luna var. aequalis by its longer valves, with striae somewhat irregularly distributed. The valve illustrated by the author (here reproduced in Fig. 27 View FIGURES 27–36 ) is elongated, with parallel margins and broadly cuneate, ventrally deflected apices. Striae are parallel and become more densely spaced at the apices, where they flank the terminal nodule (see Table 1 View TABLE 1 for morphometric data). The specimens from the original material observed with LM ( Figs 28–33 View FIGURES 27–36 ) fit rather well the original description of this form, although valve dimensions are lower than those reported by the author whereas stria densities are higher than originally reported, this difference being more marked for mid valve striae ( Table 1 View TABLE 1 ). Additionally, most specimens exhibit short dorsal striae variably extending onto the valve face ( Figs 28, 30–31, 33–34 View FIGURES 27–36 ), which were not depicted in the original illustration.

Under SEM ( Figs 34–36 View FIGURES 27–36 ) we only found one valve of this form, in internal view and slightly tilted positioned, with the closed valvocopula attached. Internal areola openings are round and are located in narrow troughs ( Fig. 35 View FIGURES 27–36 ). Due to the presence of detrital material that partially covers the valve, no details are visible regarding the internal raphe fissure and the presence of rimoportulae. The portion of the mantle visible shows the filiform raphe with its simple proximal end ( Fig. 36 View FIGURES 27–36 ). The areolation pattern between the raphe and the valve margin is denser and more disorganized than in the rest of the mantle ( Fig. 36 View FIGURES 27–36 ).

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