Odontidium parvoapiculatum Jüttner, D.M.Williams & E.J.Cox, 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 : 9-10

Odontidium parvoapiculatum Jüttner, D.M.Williams & E.J.Cox , sp. nov. ( Figs 63 – 78 )

LM ( Figs 63–70 ): Frustules rectangular in girdle view ( Figs 63, 64 ). Valves linear with valve margins tapering close to cuneate to slightly apiculate apices ( Figs 65 – 70 ). Valve dimensions (n=10): length 12.5 – 38.5 μm, width 6.0 – 8.5 μm. Primary, transapical ribs perpendicular or at an angle to sternum, 3 – 5 in 10 μm. Striae between ribs more or less perpendicular to sternum. SEM ( Figs 71–78 ): external valve surface smooth with few small spines (spinules) along valve margin including apices. In some valves, spines lacking. When present, spines located on virgae, usually in one row, irregularly spaced ( Figs 71 – 74 ). Virgae have approximately the same width, vimines much shorter. Striae uniseriate, more or less parallel throughout. Sternum slightly irregular, moderately wide extending into apical pore fields ( Figs 71 – 74 ). One rimoportula per valve located close to apical pore field, replacing 3–4 vimines within a stria. External rimoportula opens as a simple slit ( Figs 71 – 74 ). Internally, rimoportula possesses two protruding lips ( Fig. 77 ). Apical pore field at each pole composed of round porelli. Internally, ribs perpendicular or at an angle to valve margin ( Figs 75 – 77 ). Valvocopula with a row composed of 2, rarely 1 or 3 poroids on pars exterior. Copulae with a row composed of 2 or 3 poroids on pars exterior. One row composed of elongate poroids, located on pars interior of valvocopula and copulae ( Fig. 78 ).

Type: — INDIA, stream NE of Didna, Garhwal region, Uttarakhand, on stones, Ingrid Jüttner, 16.10.1995. The holotype is slide no. NMW.C.2007.006. R 35, National Museum Wales, Cardiff, UK!.

Etymology: —The name refers to the smaller size of the new species compared to O. apiculatum .

Ecology and distribution: — Odontidium parvoapiculatum was found on stones in one stream in the Garhwal region of Uttarakhand, India. The fast flowing alpine stream was located at 3430 m a.s.l. NE of the village of Didna. Its substratum was dominated by cobbles and pebbles and the conductivity was 34 μS/cm ( Table 2).

Figures

FIGURES 63–70. Odontidium parvoapiculatum. LM. Figs 63, 64. Frustules in girdle view. Figs 65–70. Valve views. NMW.C.2007.006. R35: tributary to the Nandâkini River, Garhwal, India. Scale bar = 10 μm.

FIGURES 71–78. Odontidium parvoapiculatum. SEM. Figs 71–73. Frustules in valve view. Fig. 74. Apical pore field and rimoportula. Fig. 75. Internal view of valve. Figs 76, 77. Internal views of pore field and rimoportula. Fig. 78. Girdle view showing valve mantle, valvocopula and pleurae. NMW.C.2007.006.R35. Scale bars = 2 μm (Figs 71–73, 75, 77, 78), 1 μm (Figs 74, 76).