Luticola ivetana Chattová & Lebouvier & Haan & Vijver 2017, sp. nov.

Luticola ivetana Chattová & Van de Vijver sp. nov. Figs 27‒43 Etymology

The new species was named after Mrs. Iveta Chattová, mother of the first author, on the occasion of her 50th birthday.

Type

ILE AMSTERDAM: Entrecasteaux, TAAF, sub-Antarctica, 37°51′18.6″ S, 77°31′23.5″ W, 21 Dec. 2016, B. Van de Vijver sample W030 (holo-: slide no. BR‒4495, Fig. 27; iso-: slide PLP ‒330; University of Antwerp, Belgium).

Light microscopy (Figs 27–36)

Valves elliptic-lanceolate with convex margins and broadly rounded, non-protracted apices. Valve dimensions (n = 50): length 11.0‒25.5 µm, valve width 6.0‒7.5 µm. Axial area narrow, linear, almost not widening towards the apices and central area. Central area forming a bow-tie shaped stauros. One isolated pore present in the central area, positioned close to the valve centre. Raphe filiform, straight with weakly deflected simple proximal raphe endings and elongated terminal raphe fissures. Striae radiate throughout the entire valve, 16‒18 in 10 µm.

Scanning electron microscopy (Figs 37–43)

Striae composed of 2–4 round to elongated areolae, clearly enlarged near the central area and the valve margins (Figs 37, 43). Mantle areolae very large, rounded, never slitlike (Fig. 39). Central area bordered by 1–2 rounded to weakly transapically elongated areolae. Isolated pore elliptic, clearly isolated from the central striae (Fig. 38). Raphe branches straight with short proximal raphe endings bent towards the side with the isolated pore (Fig. 42). Terminal raphe fissures hooked, continuing onto the valve mantle (Fig. 41). Internally, poroids of valve face occluded by hymens forming a continuous strip on each stria. Distinct stauros visible. Internal proximal raphe endings straight, terminating on the edge of the stauros. Distal raphe endings terminating onto small helictoglossae (Fig. 40).

So far, L. ivetana sp. nov. was observed on Ile Amsterdam only. The type locality where a large population of this new species was observed, was a small crack in a rock face at Entrecasteaux, clearly under the permanent influence of seaspray. A very thin film of water was present in the crack together with wet mud. The sample was taken by scraping off the mud and the water from the crack. Another large population where L. ivetana sp. nov. was found is a lava cavern in the partly collapsed Grand Tunnel, running from the Cratères Vénus to the northern coast. The sample was taken from wet mosses (F-value IV-V), growing on the wall of the cavern, close to the entrance, in a population of Blechnum australe L. The sample was dominated by Ferocia setosa (Greville) Van de Vijver & Houk (Van de Vijver et al. 2017), Orthoseira verleyenii Van de Vijver (Lowe et al. 2013), Sellaphora barae Van de Vijver & E.J.Cox (Van de Vijver & Cox 2013) and various Humidophila species.