The genus Odontidium (Bacillariophyta) in the Himalaya-a preliminary account of some taxa and their distribution Author Jüttner, I. National Museum of Wales, Department of Natural Sciences, Cathays Park, Cardiff, CF 10 3 NP, U. K.; Author Williams, D. M. The Natural History Museum, Department of Life Sciences, Cromwell Road, London, SW 7 5 BD, U. K.; Author Gurung, S. Author Vijver, B. Van De Botanic Garden Meise, Department of Cryptogamy (Bryophyta & Thallophyta), Nieuwelaan 38, B- 1860 Meise, Belgium; & University of Antwerp, Department of Biology, ECOBE, Universiteitsplein 1, B- 2610 Wilrijk, Antwerp, Belgium Author Levkov, Z. Author Sharma, C. M. Author Sharma, S. Author Cox, E. J. text Phytotaxa 2017 2017-12-15 332 1 1 21 http://dx.doi.org/10.11646/phytotaxa.332.1.1 journal article 10.11646/phytotaxa.332.1.1 1179-3163 13721883 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 ). FIGURES 40–54. Odontidium longiovalum . LM. Fig. 40. Frustule in girdle view. Figs 41 – 54. Valve views. Figs 40, 41, 45, 46, 48, 53, 54. NMW.C.2007.006.K58: tributary to the Ghunsa Khola near the village of Hombu, Taplejung district, Nepal. Figs 42, 47, 50, 51. NMW. C.2007.009.2000.La.spr.3/2: spring in the Langtang Valley, Rasuwa district, Nepal. Figs 43, 44, 49, 52. NMW.C.2007.006.He07: stream south of the Laurebina Pass, Helambu, Nepal. Scale bar = 10 μm. 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 ).