Adlafia muscora (Kociolek et de Reviers) Moser, Lange-Bertalot et Metzeltin.

Marquie, Julien, Cohu, Rene Le & Coste, Michel, 2018, Adlafia moseri and A. tjibaoui two new diatom species (Bacillariophyta) from New Caledonia with further observations on Adlafia muscora and Kobayasiella saxicola, Phytotaxa 357 (1), pp. 41-51 : 45

Adlafia muscora (Kociolek et de Reviers) Moser, Lange-Bertalot et Metzeltin. ( Figs 29−31 )

SEM ( Figs 29−31 ): Valves linear-lanceolate with protracted apices ( Figs 29, 30 ), axial area linear, central area hardly widened. Striae uniseriate, radiate, becoming strongly convergent towards apices ( Figs 29, 30 ). Two shortened striae present on each side of central area ( Fig. 31 ). Areolae more or less rounded, externally occluded by hymenes ( Fig. 29 ). Valve apex with two rows of areolae on mantle ( Fig. 30 ). Externally, proximal raphe endings slightly expanded, deflected towards primary side of valve. Terminal raphe fissures hooked towards secondary side ( Fig. 29 ). Internally, proximal raphe endings strongly deflected, close together. Helictoglossae poorly developed ( Fig. 30 ).

Comments: —So far, Adlafia muscora , the generitype of the genus Adlafia was only characterized by the measurements given by Manguin (19.5 μm long by 3.5 μm wide, 23–26 striae in 10 μm), under the name Navicula bryophyloides Manguin (1962: 19) . As this species frequently occurs in some of samples used in the present study, a detailed analysis was performed resulting in more than 50 SEM observations. This resulted in a better characterization of the morphology of this species. Recently, Tusset et al. (2017) recorded A. muscora (n=40) in Brazil, defining more precisely its stria density and size range. Based on our observations and those of Tusset et al. (2017), the range of the three parameters cited above can be emended, length: 8.5–9.5 μm, width: 3.0–4.5, stria density: 28–36 in 10 μm. Our observations are congruent with those provided by Tusset et al. (2017) apart for the maximum width (4.0 vs 4.5) and the minimum stria number of (32 vs 28 in 10 μm). It needs to be premised that very short striae (one or two areolae), located around the central area, are not discernible in LM, explaining most likely the difference between the stria density indicated by Manguin (1962) and the stria density observed in the present study and Tusset et al. (2017).

Figures

FIGURES 29–31. Adlafia muscora SEM. 29. External view of an entire valve. GFig. 30. Internal view of an entire valve. Fig. 31. Detail of the internal proximal raphe fissures strongly bent towards the primary side and very close each other. Scale bars = 2 μm (Figs 29, 30), 1 μm (Fig. 31).