Humidophila crozetikerguelensis (Le Cohu & Van de Vijver) R.L.Lowe et al., 2014

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 : 32

Humidophila crozetikerguelensis (Le Cohu & Van de Vijver) R.L.Lowe et al. ( Figs 39–59 )

Morphological observations:—Larger specimens linear with strongly undulating margins and broadly rounded subcapitate apices, smaller specimens linear with more parallel margins, usually lacking the typical double undulation and the gibbous apices. Valve dimensions (n=20): length 11.2 – 14.9 μm, width 2 – 3.2 μm. Width of the apices never extend beyond the valve undulations. Axial area well-defined, linear. Central area widened, generally bordered by 3 striae. Raphe straight filiform with only slightly marked endings. Distal raphe endings terminating near the last striae. Striae slightly radiate in the middle, becoming more convergent towards the apices, 32 – 34 in 10 μm. Mantle areolae elongated, continuing around the apices lacking an interruption at the apices.

56. SEM of internal valve view. 57–58. SEM of an entire valve (externally). 59. SEM of internal valve view. LM scale bar = 10 μm. SEM scale bars = 5 μm.

Ecology and associated diatom flora:— Humidophila crozetikerguelensis is originally described from Kerguelen, where it is common in semi-wet soils with higher specific conductance values and higher phosphorous and chloride concentrations ( Le Cohu & Van de Vijver 2002). On Ile Amsterdam, the species was found in high abundance on both wet and terrestrial mosses with a wide F-value range of II–VII, and occasionally on wet mosses and soils on Ile Saint Paul. The associated diatom community is composed of other Humidophila species ( Humidophila amsterdamensis , H. rouhaniana , H. vidalii , H. contenta ), Eunotia paludosa , Achnanthes coarctata (Brébisson ex W. Smith 1855: 8) Grunow in Cleve & Grunow (1880: 20), Frustulia lebouvieri and Eunotia muscicola .

Figures

FIGURES 39–59. Humidophila crozetikerguelensis (Le Cohu & Van de Vijver) R.L.Lowe et al. Light (LM) and scanning electron micrographs (SEM). 39–55. LM of valve views.