Sellaphora gracillima Zidarova, Kopalová & Van de Vijver, 2016

Zidarova, Ralitsa, Kopalová, Kateřina & Vijver, Bart Van De, 2016, Ten new Bacillariophyta species from James Ross Island and the South Shetland Islands (Maritime Antarctic Region), Phytotaxa 272 (1), pp. 37-62 : 51-52

publication ID

https://doi.org/ 10.11646/phytotaxa.272.1.2

DOI

https://doi.org/10.5281/zenodo.13647392

persistent identifier

https://treatment.plazi.org/id/03FF7D6E-FFA7-1F77-FF0C-5780FA4BF643

treatment provided by

Felipe

scientific name

Sellaphora gracillima Zidarova, Kopalová & Van de Vijver
status

sp. nov.

Sellaphora gracillima Zidarova, Kopalová & Van de Vijver , sp. nov. ( Figs 157–177 View FIGURES 157–177 )

LM observations ( Figs 157–174 View FIGURES 157–177 ): Valves linear to linear-elliptic with almost parallel or weakly convex valve margins. Apices non protracted, broadly rounded. Valve dimensions (n=25): length: 8.5–14.0 μm, width 2.5–3.5 μm. Axial area very narrow, linear. Central area moderately large, transapically elongated, rounded ( Fig. 157 View FIGURES 157–177 ) to rectangular ( Fig. 172 View FIGURES 157–177 ) but often asymmetrical in shape due to several (2–5) irregularly shortened striae. Raphe filiform with straight, indistinct proximal raphe endings. Distal raphe endings not discernible in LM. Striae fine, radiate throughout the entire valve, 30–32 in 10 μm. Striae near the central area weakly curved. Areolae not visible in LM. SEM observations ( Figs 175–177 View FIGURES 157–177 ): Externally, valve face flat ( Figs 175, 177 View FIGURES 157–177 ). External raphe branches straight to slightly curved ( Fig. 175 View FIGURES 157–177 ). Proximal raphe endings weakly and gradually expanded, almost straight to weakly unilaterally deflected ( Fig. 175 View FIGURES 157–177 ). Distal raphe fissures elongated, hooked opposite the proximal raphe endings, continuing onto the mantle beyond the last striae ( Fig. 175 View FIGURES 157–177 ). Striae uniseriate, composed of small rounded areolae, shortly extending onto the mantle to just below the valve face/mantle junction ( Figs 175, 177 View FIGURES 157–177 ). Areolae near the axial area slightly larger than the others ( Fig. 175 View FIGURES 157–177 ). Open foramina present at the apices ( Fig. 175 View FIGURES 157–177 ). Internally ( Fig. 176 View FIGURES 157–177 ), raphe straight. Proximal raphe endings terminating on a thickened central nodule, weakly deflected. Distal raphe endings terminating onto weakly developed helictoglossae. Internal areolar openings rounded, covered by individual, porous hymenes ( Fig. 176 View FIGURES 157–177 ). Shallow depressions present at both valve apices ( Fig. 176 View FIGURES 157–177 ). Girdle composed of 2 open copulae, the valcocopula bearing a single row of small rounded poroids ( Fig. 177 View FIGURES 157–177 ).

Type: — ANTARCTICA. South Shetland Islands: Livingston Island, Byers Peninsula, sample BY049 (62° 38’ 43.1” S, 61° 02’ 22.9” W, 75 m a.s.l.), B. Van de Vijver, 14 January 2009 (holotype BR! 4458, isotype PLP! 312).

Etymology: —The specific epithet ‘ gracillima ’ refers to the fine striation of the species.

Ecology and confirmed distribution: — Sellaphora gracillima has been probably reported in the past as Eolimna (Navicula) minima (Grunow in Van Heurck 1880: 107) Lange-Bertalot in Moser et al. (1998: 153) or as Navicula tantula Hustedt (1943: 162) on several localities in the Maritime Antarctic Region ( Kellogg & Kellogg 2002, Kopalová & Van de Vijver 2013, Kopalová et al. 2013, 2014, Sterken et al. 2015, figs 3AX, AY). So far, it is only with certainty present on Livingston Island, South Shetland Islands. The largest population was observed in a lake situated on the main central plateau on Byers Peninsula, next to Limnopolar Lake at an altitude of 75 m. The lake has a pH of 7.6 with a conductivity value of 60 μS/cm. Both nutrient and mineral levels are quite low ( Kopalová & Van de Vijver 2013).

BR

Embrapa Agrobiology Diazothrophic Microbial Culture Collection

PLP

Institute of Himalayan Bioresource Technology

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