Odontidium nepalense Jüttner, S.Gurung, Van de Vijver & D.M.Williams, 2017

Jüttner, I., Williams, D. M., Gurung, S., Vijver, B. Van De, Levkov, Z., Sharma, C. M., Sharma, S. & Cox, E. J., 2017, The genus Odontidium (Bacillariophyta) in the Himalaya-a preliminary account of some taxa and their distribution, Phytotaxa 332 (1), pp. 1-21 : 3-7

Odontidium nepalense Jüttner, S.Gurung, Van de Vijver & D.M.Williams , sp. nov. ( Figs 2 – 22 )

LM ( Figs 2–14 ): Frustules rectangular in girdle view ( Fig. 2 ). Valves linear-lanceolate to elliptic with margins tapering from valve centre, strongly and evenly tapered near apices ( Figs 3 – 14 ).Apices cuneate, narrowly rounded, occasionally acute, particularly in larger valves ( Figs 3 – 14 ). Valve dimensions (n=27): length 22.0 – 63.5 μm, width 8.5 – 12.0 μm. Transapical ribs primary, few secondary ribs present. Transapical ribs perpendicular or at an angle to sternum, 3 – 5 in 10 μm. Striae between ribs at slight angle or perpendicular to sternum, 2 – 9(10) rows between ribs. Sternum broad, 1/5 of valve width. Cingulum composed of several bands ( Fig. 2 ). SEM ( Figs 15–22 ): external valve surface slightly rippled. Many marginal linking spines, almost one per virga, on occasion two, of variable length, tapering towards tips, present at apices, somewhat irregularly situated ( Figs 15 – 17 ). Larger spines arranged more or less in one row on the valve face/mantle junction ( Fig. 16 ), smaller spines positioned between the larger spines, in addition forming an irregular row on the mantle ( Figs 16, 18 – 20 ). Virgae of varying widths but more or less regular, vimines narrower ( Figs 16, 17 , 22 ). Striae uniseriate, either more or less parallel or slightly oblique, sometimes slightly curved, often slightly radiate towards the poles ( Figs 16, 17 ). Areolae occluded externally. Striae of varying length bordering a wide, ill-defined sternum ( Figs 16 , 21 ). Sternum becoming narrower close to and extending into pore field ( Figs 16, 17 , 21, 22 ). One rimoportula present near apical pore field, replacing 3 – 5 vimines within a stria. External rimoportula opens as simple slit ( Figs 15 – 17 ). Internally, rimoportula with two protruding lips ( Fig. 22 ). Apical pore field present at each apex, composed of round porelli surrounded by a rim ( Figs 16, 17 , 22 ). Outer surface of mantle and girdle bands covered with small nodules ( Figs 18 – 20 ). Nodules more or less round on girdle bands, but often scale-like and irregular on mantle ( Figs 19, 20 ). Mantle margin slightly undulate ( Figs 18 – 20 ). Cingulum composed of valvocopula and 4–6 copulae ( Figs 18 – 20 ). Valvocopula with a row of 2 – 3 poroids on the pars exterior, whereas on copulae with a row composed of 1 or 2 poroids ( Figs 19, 20 ) and a single row of elongated poroids present on the pars interior ( Fig. 20 ). Internally ribs positioned slightly at an angle or perpendicular to the sternum and wider than virgae ( Figs 21, 22 ).

Type: — NEPAL, Terkeghyang, Sindhupalchok district, Helambu, spring sample, on bryophytes, I. Jüttner, 28.2.2008. The holotype is slide no. NMW.C.2011.030.2008.Helan.spr.8.bryo, National Museum Wales, Cardiff, UK!.

Etymology: —The name refers to the country ( Nepal) where the species is found.

Ecology and distribution:— Odontidium nepalense was found on sand, stones and bryophytes in streams and in a spring in central and eastern Nepal. In the Helambu area of central Nepal (NMW.C.2011.030.2008.Helan.spr.8.bryo) the species was found on submerged bryophytes in a small, slightly shaded spring, located on a steep slope with deciduous forest and shrub (NO 3 0.27 mg /L, PO 4 0.15 mg /L, SO 4 0.42 mg /L, Ca 2.16 mg /L, Na 1.43 mg /L, Si 5.62 mg / L). In eastern Nepal, in the Gokyo Valley of the Everest National Park, it occurred in two alpine streams, one flowing into the lake Dudh Pokhari at its western shore (NMW.C.2009.003.51, G3 inlet north face sand), the other flowing into the first lake in the lake series west of the Ngozumpa Glacier (NMW.C.2009.003.122, G1 inlet sediment). In the

Makalu area O. nepalense was found in a tributary to the Barun Khola, a small alpine stream, 1 m wide with 60%

pebble and gravel substratum (NMW.C.2007.006.M60, Table 2).

Figures

FIGURES 2–14. Odontidium nepalense. LM. Fig. 2. Frustule in girdle view. Figs 3–14. Valve views. Figs 2–7. NMW.C.2011.030.2008. Helan.spr.8.bryo: spring in Terkeghyang, Helambu, Nepal; Figs 8–14. NMW.C.2009.003.51: inflow of Dudh Pokhari, Everest National Park. Scale bar = 10 μm.

FIGURES 15–18. Odontidium nepalense. SEM. Figs 15, 16. Frustules in valve view. Fig. 17.Apical pore field and girdle bands at pole. Fig. 18. Frustule in girdle view. Figs 15, 17, 18. NMW.C.2011.030.2008.Helan.spr.8.bryo. Fig. 16. NMW.C.2009.003.51. Scale bars = 2 μm.

FIGURES 19–22. Odontidium nepalense. SEM. Fig 19. Mantle with rows of spines, and two girdle bands. Fig. 20. Mantle and girdle bands. Fig. 21. Internal view of valve. Fig. 22. Internal view of apical pore field and rimoportula. Figs 19, 20, 22. NMW.C.2011.030.2008. Helan.spr.8.bryo. Fig. 21. NMW.C.2009.003.51. Scale bars = 2 μm (Figs 19, 21, 22), 1 μm (Fig. 20).