Humidophila rouhaniana Chattová & Van de Vijver, 2018

Chattová, Barbora, Lebouvier, Marc & Vijver, Bart Van De, 2018, Morphological and taxonomical analysis of the terrestrial diatom genus Humidophila (Bacillariophyta) on Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean), Phytotaxa 336 (1), pp. 28-42 : 36-37

Humidophila rouhaniana Chattová & Van de Vijver sp. nov. ( Figs 122–144 )

Light microscopy ( Figs 122–140 ): Valves linear with almost parallel to sometimes even slightly asymmetrical margins and broadly rounded apices. Smaller specimens occasionally with a more linear–elliptic valve outline. Valve dimensions (n = 50): length 7.5 – 16.0 μm, width 1.5–3.0 μm. Axial area linear, rather broad, slightly narrowing towards the poles. Raphe filiform, straight. Central area stauroform, reaching the valve margins. Transapical striae not discernible in LM, interrupted centrally.

SEM ( Figs 141–144 ): Striae composed of one transapically weakly elongated, near apices almost rounded areola ( Fig. 143 ), ca. 45 in 10 μm. At the apices, striae usually terminating near the distal raphe endings, sometimes beyond the distal raphe endings ( Figs 142 and 143 ). Mantle areolae continuing around the apices ( Fig. 144 ). External raphe branches straight with clearly depressed proximal and distal pores with distinctly depressed bow-tie endings ( Fig. 142 ). Internal structure not observed. Valve face and mantle areolae separated by a narrow longitudinal groove. Girdle composed of three copulae, perforated by a single row of elongated, slit-like pores ( Fig. 141 ).

Type:— ILE AMSTERDAM, TAAF sample AMS-M201, B. Van de Vijver , 15 December 2007 (holotype: BR! slide no. 4489; isotype: PLP! slide no. 327, University of Antwerp, Belgium). The holotype specimen is represented by fig. 124 .

Etymology: The new species is named after Dr. Germinal Rouhan (Muséum National d’Histoire Naturelle, Paris, France) to thank him for the wonderful joint field work on Ile Amsterdam in November–December 2016.

Ecology and associated diatom flora:—The type population of Humidophila rouhaniana was found in an almost dry moss sample (F-value VII) taken from the Jardin Météo on the vicinity of the base Martin-de-Viviès. The associated community is composed of several Humidophila species (such as H. amsterdamensis and H. vidalii ), Halamphora dagmarobbelsiana Van de Vijver & Levkov (in Van de Vijver et al. 2014: 384), Chamaepinnularia aerophila and an at present unidentified Nitzschia species.

Figures

FIGURES 122–144. Humidophila rouhaniana Chattová & Van de Vijver sp. nov. Light (LM) and scanning electron micrographs (SEM). 122–140. LM of valve views of the type population from Ile Amsterdam. 141–144. SEM of external valve view showing the stauroform central area and the raphe with depressed proximal and distal pores with distinct bowtie endings. LM scale bar = 10 μm. SEM scale bars = 1 μm.