Pinnularia gemella Van de Vijver
- Dataset
- The genus Pinnularia (Bacillariophyta) excluding the section Distantes on Livingston Island (South Shetland Islands) with the description of twelve new taxa
- Rank
- SPECIES
Classification
- kingdom
- Chromista
- phylum
- Bacillariophyta
- class
- Bacillariophyceae
- order
- Naviculales
- family
- Naviculaceae
- genus
- Pinnularia
- species
- Pinnularia gemella
description
Habitat: — Pinnularia gemella was found in several larger lakes on the central plateau of Byers Peninsula. All lakes had a pH varying between 7.2 and 7.5 and a very low specific conductance level (<60 µS / cm). The species seems to be absent from Hurd Peninsula.
description
Valves linear with strictly parallel margins and broadly rounded, non-protracted apices. Valve dimensions (n = 20): length 43 – 52 µm, width 7.3 – 8.8 µm. Axial area moderately broad, linear to linear-lanceolate, not, or only very slightly, widening towards the central area. Central area forming a rectangular, usually asymmetrical fascia. Raphe lateral with deflected proximal raphe endings terminating in weakly expanded pores. Distal raphe fissures bayonet-shaped. Striae almost parallel throughout the entire valve. Longitudinal lines absent. One single row of small spines visible on the primary side, 9 – 10 in 10 µm. Valves usually found in pairs, connected by linking spines, lying in juxtaposition. Habitat: — Pinnularia gemella was found in several larger lakes on the central plateau of Byers Peninsula. All lakes had a pH varying between 7.2 and 7.5 and a very low specific conductance level (<60 µS / cm). The species seems to be absent from Hurd Peninsula.
discussion
Observations: — Pinnularia gemella cannot be mistaken with any other species of Pinnularia due to the presence of the spines on the primary side. Only a few Pinnularia species have spines or form colonies in juxtaposition. Van de Vijver et al. (2004 a, 2009) reviewed all colony- and / or spine-forming species of Pinnularia. Pinnularia subantarctica var. elongata has a similar valve outline but higher stria density and lacks the typical spines of P. gemella.
Name
- Homonyms
- Pinnularia gemella Van de Vijver