Ferocia houkiana Goeyers & Van de Vijver, 2020

Goeyers, Charlotte & Vijver, Bart Van De, 2020, Revision of the non-marine centric diatom flora (Bacillariophyta) of the sub-Antarctic Campbell Island (southern Pacific Ocean) with the descriptions of five new species, European Journal of Taxonomy 694, pp. 1-30 : 9-12

Ferocia houkiana Goeyers & Van de Vijver sp. nov.

http://phycobank.org/ 102316 Figs 44–73

Etymology

The species is named in honour of our colleague and friend Dr Václav Houk (Institute of Botany, Czech Republic) to acknowledge him for his work on melosiroid diatoms.

Material examined

Holotype

CAMPBELL ISLAND • sub-Antarctic region ; sample BAS284; 12 Jan. 1970; D. Vitt leg.; BR-4578 .

Isotype

CAMPBELL ISLAND • same collection data as for holotype; slide at University of Antwerp, Belgium; PLP-369 .

Description

Light microscopy ( Figs 44–62 )

Frustules rectangular. Cells connected via a central ring of spines, forming short chains. Numerous discoid plastids present. Girdle composed of large number of very narrow copulae, covering two adjacent valves. Valve diameter (n = 20): 4–11 μm, mantle height (n = 5): 4.0–5.5 μm. Valves with a relatively low mantle and rounded, flat valve face. Internal valves occasionally observed ( Figs 50–51 ). Central area dominated by a regular crown of spines. Scattered spines present on the entire valve face. Striae not discernible in LM.

Scanning electron microscopy ( Figs 63–73 )

Girdle composed of a large number (up to 20) of narrow, open, non-perforated copulae ( Fig. 63 ). Girdle bands attached to one of the valves of a cell extending over one of the new daughter valves after each cell division, meeting and overlapping with the bands attached to the other parent valve, covering that way two new valves of the daughter cells ( Fig. 63 ). Copulae fimbriate on pars inferior giving the misleading impression of perforated girdle bands in non-eroded girdles ( Figs 63, 65 ). Valves connected via central crown of large, wedge-shaped spines ( Fig. 64 ). Müller step on mantle occasionally observed ( Fig. 66 , arrow). Mantle striae straight, composed of small, rounded areolae ( Figs 64, 66 ). Near mantle edge, areolae very much smaller than near and at valve face/mantle junction, areolae irregularly scattered ( Fig. 64 ). Mantle edge not rimmed. Rimoportula openings on the mantle not distinguishable from mantle areolae. Valve face/mantle junction thickened, relatively abrupt ( Figs 63, 66 ). Valve face dominated by a central regular ring of large, relatively low, wedge-shaped spines ( Figs 67–68 ). Spines hollow but apparently chambered with small silica walls inside the spines ( Fig. 68 ). Spines occasionally lacking or reduced to series of low silica outgrowths ( Fig. 69 ). Central area clearly raised, bordered by a narrow flat valve face edge, covered by an irregular pattern of small, rounded to slit-like areolae ( Figs 67, 68 , arrows). Striation pattern not detectable in the areolae. Internally, a few sessile rimoportula visible close to the mantle edge ( Figs 71, 72 , arrows), irregularly scattered. One rimoportula present near the valve center on the valve face ( Figs 70, 73 , arrow). Internal valve surface covered by numerous small areolae ( Fig. 73 ).

Ecology and distribution

Ferocia houkiana sp. nov. is a frequently observed species on Campbell Island. It was found in several moss samples on rocks and next to waterfalls, usually dominated by species belonging to the genera Pinnularia , Pinnunavis and Eunotia . The type sample is dominated by the new species of Ferocia and is accompanied by Pinnularia borealis s. lat. Ehrenb. which points to a drier character of the environment, often influenced by sea spray ( Van de Vijver et al. 2002).

Figures

Figs 44–66. Ferocia houkiana Goeyers & Van de Vijver sp. nov. LM and SEM. Campbell Island holotype population, sample BAS284 (BR-4578). LM. 44–49. Several frustules in girdle view, often connected to each other. 50–51. Internal valves. 52–62. Several valves in valve face view clearly showing the central ring of spines. SEM. 63. Frustule in girdle view with the narrow copulae. 64. Frustule in girdle view with the narrow copulae on one side and one the side showing the broad mantle with one indicated rimoportula. 65. External view of a valve face and the girdle. Note the central ring of partly hollow spines. 66. External view of two valves connected via their linking spines. The arrow indicates the Müller step. Scale bars = 10 μm.

Figs 67–73. Ferocia houkiana Goeyers & Van de Vijver sp. nov. SEM. Campbell Island holotype population, sample BAS284 (BR-4578). 67–68. Two external valve face views with the typical spines, the rounded to slit like areolae and the Müller step. 69. External girdle view of a valve lacking the typical central ring of spines. Note the spines vestiges that are present in the central area. 70. Internal view of an entire valve showing clearly the central rimoportulae (arrow) and the small central area. 71. Internal view of an entire valve showing clearly the submarginal rimoportulae (arrows). 72. Internal detail of the valve with one rimoportula indicated by the arrow. 73. Internal detail of the valve central area with the central rimoportula. Scale bars: 67, 69–70 = 10 μm; 68, 71 = 5 μm; 72–73 = 1 μm.