Pinnularia magnifica, Zidarova & Kopalová & Vijver, 2012

Zidarova, Ralitsa, Kopalová, Kateŕina & Vijver, Bart Van De, 2012, The genus Pinnularia (Bacillariophyta) excluding the section Distantes on Livingston Island (South Shetland Islands) with the description of twelve new taxa, Phytotaxa 44, pp. 11-37 : 18-20

Pinnularia magnifica sp. nov. ( Figs 75–101 )

Valvae clare lanceolatae ad etiam rhombicae-lanceolatae marginibus semi-rhomboidalibus ad convexis, apicibus leviter ad moderate protractis,cuneiformibus. Longitudo 22–32 µm, latitudo 4.9–6.0 µm. Area axialis angusta, linearis, aliquando dilatans in aream centralem. Area centralis formans fasciam cuneiformem latam. Raphe filiformis, ramis leviter curvatis. Terminationes raphis proximales leviter unilateraliter deflexae cum poris paene indistinctis. Fissurae raphis distales similes signo interrogationis. Striae moderate ad fortiter radiatae in media parte valvae, moderate ad fortiter convergentes ad apices, 9–10 in 10 µm. Lineae speciosae longitudinales nullae.

Valves clearly lanceolate to even rhombic-lanceolate with semi-rhomboidal to convex margins and cuneiform, weakly to moderately protracted apices. Valve dimension (n=33): length 22–32 µm, width 4.9–6.0 µm. Axial area narrow, linear, slightly widened towards the central area. Central area large, forming a bowtie-shaped fascia. Raphe filiform with weakly curved raphe branches. Proximal raphe endings slightly deflected to one side, with small, almost indistinct central pores. Terminal fissures?-shaped. Striae moderately to strongly radiate in the middle, becoming moderately to strongly convergent towards the ends, 9–10 in 10 µ m. Longitudinal lines absent.

Type:— Byers Peninsula, Livingston Island , South Shetland Islands , sample BYS012, leg. B. Van de Vijver, coll. date 14/01/2009, slide no. BR-4254 (holotype BR, slide PLP-199 (isotype University of Antwerp, Belgium), slide ZU8/23 (isotype BRM).

Habitat:— Pinnularia magnifica was frequently found on Livingston Island in small streams, pools and seepage areas with an alkaline pH and low specific conductance.The species has not been recorded in larger lakes. It is also observed in very low abundance on semi-wet and moist moss vegetation surrounding shallow water pools and on soil.

Etymology:—The specific epithet represents the esthetical appreciation of the authors for this species (Latin magnificus means splendid, magnificent).

Observations:— Pinnularia magnifica can hardly be confused with other Pinnularia species , based on its combination of radiate striae, low stria density and large, bowtie-shaped fascia. Pinnularia acoricola Hust. (in A. Schmidt 1934: 390) has a different striation pattern with a sudden shift in direction halfway down the valve and a higher stria density (13–16 in 10 µm vs. 9–10 in 10 µm). Pinnularia obscura shows a comparable shift in stria direction to P. acoricola and has a different valve outline with more rostrate apices. Another similar species is P. cuneola Reichardt (1981: 501) but it is larger (width 6–8 µm vs. 4.9–6 µm) with less protracted apices. The closely related P. insidiosa Manguin (1964: 81) , described from the Peruvian Andes, has a similar striation pattern and a similar stria density but shows a different valve outline with less protracted apices ( Manguin 1964).

Figures

FIGURES 48–101. Pinnularia australoschoenfelderi sp. nov. and Pinnularia magnifica sp. nov. from Livingston Island. Figs 48–74. LM of P. australoschoenfelderi sp. nov.. Figs 75–101. LM of P. magnfica sp. nov. Scale bar = 10 µm.