Analysis and critical evaluation of structural features in four Cymbellaceae taxa from New Caledonia

Abstract

Delicatophycus costei (Lange-Bertalot et Moser) Wynne, Cymbella bourrellyi Maillard, Cymbella latarea Maillard and Cymbella pernodensis Maillard are endemic to New Caledonia and show uncommon morphological features compared to the "sensu stricto" definition of their respective genus. Delicatophycus costei was described based on light microscopy and scanning electron microscopy (SEM) observations, confirming the generic LM diagnosis. However, the external view in SEM is atypical as both valve face and mantle are covered by longitudinal ribs, overlaying part of the zigzag striae, generally accepted as the determinant generic feature. The three species of Cymbella have both apical pore fields and "stigmata". However, they show some specific morphological features compared to the more classically shaped Cymbella species. Cymbella bourrellyi has a narrow hyaline area on the valve face and the areolae are bordered internally by small outgrowths. Cymbella pernodensis is distinguished by internal biseriate striae. The internal morphology of Cymbella latarea is characteristic in having typical biseriate striae and bisected apical pore fields. In these three species, internally, the stigmata are continuous with the striae and appear as simple and only weakly separated structures at the end of the striae. The three species are also characterized by differences in the number of areola rows per stria externally and internally.

Encyonopsis indonesica sp. nov. (Bacillariophyceae, Cymbellales), a new diatom from the ancient lake Matano (Sulawesi, Indonesia)

“… Celebesia distinguenda (Hustedt) Kapustin, Kulikovskiy & Kociolek, Cymbella eunotioformis Kapustin, Kociolek & Kulikovskiy, C. densigranulata Kapustin, Kociolek & Kulikovskiy, Gomphonema matanense Kapustin, Kociolek & Kulikovskiy and Encyonopsis indonesica are additionally ornamented with siliceous outgrowths, ridges, granules, or spines ( Kapustin et al 2017 , 2019 ; Kociolek et al 2018 ). This situation was also shown for another cymbelloid taxon, in a species of Delicatophycus Wynne ( Le Cohu et al 2020 ) described from New Caledonia. Since silicification in diatoms is genetically encoded (e.g.…”

The Perizonium Ultrastructure, Divided Apical Pore Fields, Various Pore Occlusions and Visible Intermissio in Cymbella (Bacillariophyceae) with Descriptions of Four New Species

“…hustedtii [1] p.577, plate 193, Figures 1, 4 C. latarea [8] p. 81, Figures 42, 44 C. loescherae [9] p. 193, Figure 15 C.…”

Three New Diatom Species from Spring Habitats in the Northern Apennines (Emilia-Romagna, Italy)

“…The morphology of the taxa belonging to Delicatophycus is characterized by dorsiventral valves with a lateral structure of the raphe, the presence of pseudosigmoids, the absence of apical pore fields and of stigmata, and foramina with a tendency to form undulated transapical structures externally. The species have strongly ventrally curved proximal raphe branches, distal raphe fissures deflected dorsally, with combination of the partly zig-zag shaped striae [50,52]. The representatives of the genus are found across a large climatic and geographical range: Europe [50], Asia [53,54], Africa [50], and South and North America [55,56].…”