Orthoseira hawaiiensis Danz & Kociolek

Kochman-Kedziora, Natalia & Van de Vijver, Bart, 2024, The genus Orthoseira (Orthoseiraceae, Bacillariophyta) in Papua New Guinea with the description of two new species, Plant Ecology and Evolution 157 (2), pp. 113-124 : 113

publication ID

https://dx.doi.org/10.5091/plecevo.115801

persistent identifier

https://treatment.plazi.org/id/954A5C32-D3E8-5DB7-AB5B-16CAA4B192A8

treatment provided by

by Pensoft

scientific name

Orthoseira hawaiiensis Danz & Kociolek
status

 

Orthoseira hawaiiensis Danz & Kociolek

Fig. 1 View Figure 1

Material used.

Sample 110 (Karkar Island, Village of Mom, Papua New Guinea).

LM description.

Frustules cylindrical in girdle view, usually solitary. Valves disc-shaped. Valve dimensions (n = 15): diameter 13-30 μm, mantle height 5.0-7.5 µm. Valve surface flat, sloping abruptly at the valve face/mantle junction, visible in LM as a darker circular edge. Central area small, maximum 1/4 to 1/5 of the total valve diameter, rounded. Three (very rarely 2) large, rounded carinoportulae present, number constant irrespective of the valve diameter. Valve face areolae small, arranged in radiate, uniseriate striae of variable length, 18-24 in 10 μm. Striae often branching near the valve margin. Short, irregular ridges present, scattered over the entire valve face, visible at different focal level (Fig. 1A View Figure 1 ). Presence of caverns along the edge of the mantle, visible as regular, darker areas, 5-7 per valve. Figure 1A-D View Figure 1 .

SEM description.

Cingulum composed of several broad, open, ligulate copulae, perforated with at least 5-7 parallel rows of very small pores (Fig. 1E-G View Figure 1 ). Valvocopula with thin, broad extensions, covering plate-like the valve interior (Fig. 1F, M View Figure 1 ). Mantle shallow (Fig. 1E, G View Figure 1 ), occasionally with a clear step halfway the valve mantle (Fig. 1E View Figure 1 ). Advalvar part of the mantle with regular striation pattern. Mantle striae composed of up to 10 areolae, 22-25 in 10 µm (Fig. 1E, G View Figure 1 ). Valve face flat. Central area hyaline, small. Three (rarely two, see Fig. 1E View Figure 1 ) carinoportulae visible with raised, irregularly shaped, cylindrical collar (Fig. 1H, I View Figure 1 ), occasionally obscured by a plate-like covering (Fig. 1H View Figure 1 ). Valve face entirely covered by an often network-like raised pattern of ridges (Fig. 1E, H-J View Figure 1 ). Halfway between valve edge and centre, several much denser groupings of short and longer ridges present, regularly placed in a ring around the central area (Fig. 1E, H-J View Figure 1 ). Striae uniseriate, composed of small, rimmed areolae (Fig. 1J View Figure 1 ). Short, thick acute marginal spines present at the valve face/mantle junction (Fig. 1E, G View Figure 1 ). Marginal pore fields present (Fig. 1E, G View Figure 1 ). Areolae covered in the valve interior by individual hymenate vela (Fig. 1K, L View Figure 1 ). Carinoportulae pit-like, visible as large, rounded depressions, filled with irregular siliceous outgrowths (Fig. 1K, L View Figure 1 ). Between the carinoportulae, several long slits present, arranged in a star-shaped manner (Fig. 1L View Figure 1 ). Internal caverns visible as shallow depressions on the valve face/mantle junction (Fig. 1K View Figure 1 ). Figure 1E-M View Figure 1 .