Encyonema keshrii S.Roy, C.Radhakrishnan, J.C.Taylor, Kulikovskiy & B.Karthick, 2020

Roy, Surajit, Radhakrishnan, Cheran, Taylor, Jonathan C., Kulikovskiy, Maxim S. & Karthick, Balasubramanian, 2020, Encyonema keshrii, sp. nov.: a new diatom species (Cymbellales, Bacillariophyceae) from the Indian subcontinent, Cryptogamie, Algologie 20 (2), pp. 7-17 : 11-14

publication ID	https://doi.org/ 10.5252/cryptogamie-algologie2020v41a2
persistent identifier	https://treatment.plazi.org/id/03B087F5-FF9B-D628-D510-9AD90720FA1F
treatment provided by	Felipe
scientific name	Encyonema keshrii S.Roy, C.Radhakrishnan, J.C.Taylor, Kulikovskiy & B.Karthick
status	sp. nov.

Treatment

Encyonema keshrii S.Roy, C.Radhakrishnan, J.C.Taylor, Kulikovskiy & B.Karthick , sp. nov.

( Figs 1-6 View FIG View FIG View FIG View FIG View FIG View FIG )

HOLOTYPE SPECIMEN. — Slide no. #24-73 from sample no. #1187 (Holotype here designated, illustrated in Fig. 1F View FIG ), Collected on 2December 2017 and deposited in at the Agharkar Research Institute Herbarium ( AHMA), Diatom Section, India. TYPE LOCALITY. — Masilla Waterfalls (locally known as Masilla Aruvi), Aariyur Panchayat , Kolli Hills (11.3034°N, 78.3939°E, altitude 1121 m above sea level), Namakkal district , Tamil Nadu, India. GoogleMaps

HABITAT. — Epiphytic in lotic freshwater.

ETYMOLOGY. — This species is dedicated to the Indian Phycologist Prof. Jai Prakash Keshri (The University of Burdwan, West Bengal, India) whose contribution to Indian phycological research is hereby acknowledged and who was the Ph.D. supervisor of SR.

ECOLOGY AND DISTRIBUTION. — This species is known from the Eastern Ghats (Masilla Waterfalls, Kolli Hills Tamil Nadu), the Western Ghats (Sharavathi River at Padambile village near Jog Falls, Karnataka) and the Eastern Himalayas (stream near Nongstoin Town, Meghalaya). Across all the sites, it occurs in low conductivity and oligotrophic conditions.

ADDITIONAL MATERIAL. — Figs 5 View FIG ; 6 View FIG show LM and SEM views of the new taxon from Sharavathi River in Karnataka of the Western Ghats. All morphometric data (n = 55) (L = 15.30-31.34 µm, W = 3.56-4.55 µm with 12-14 striae in 10 µm, n = 55), valve shape and characteristic observed under SEM matched with E. keshrii , sp. nov. The water quality recorded for the Western Ghats sampling site was pH = 7.72, dissolved oxygen (DO) = 7.66 mg /L, water temperature = 28.6 °C, nitrate = 0.3 mg /L, phosphate = 2.26 mg /L.

DESCRIPTION

LM ( Fig. 1 View FIG )

Valves lanceolate to linear-lanceolate, slightly dorsiventral, weakly heteropolar with rounded to acute apices, never protracted. Valves 15.33-30.82 µm long and 3.50-4.67 µm

broad with 13-14 striae in 10 µm (n = 51). Areolae are not discernible in LM. Raphe weakly lateral with proximal endings slightly curved towards the dorsal margin, endings rounded and pore-like. Distal raphe endings sickle-shaped and curved towards the ventral margin. Stigma absent. Axial area narrow, lanceolate widening slightly in the centre but no distinct central area is present.

SEM ( Figs 2-4 View FIG View FIG View FIG )

In external valve view ( Fig. 2 View FIG ) striae composed of one to four linear areolae ( Fig. 2A, B View FIG ) (compare to internal view of valve: Fig. 3 View FIG C-E). Striae interrupted at the valve margin and then continue on the valve mantle ( Figs 2A View FIG ; 4A, D View FIG ). Raphe lateral and curving towards the dorsal margin in the central region ( Fig. 2B View FIG ). A higher number of areolae in each striae occur adjacent the axial area with the final areolae near the margin being a single large lineolate areolus ( Fig. 2C View FIG ). Areolae do not appear to be occluded by cribra or hymenes and are 33-41 in 10 µm ( Fig. 2A, B View FIG ). Mantle perforated by small linear poroids at the apices ( Fig. 2D, F View FIG ). Proximal raphe endings curved towards the dorsal margins, pore like and slightly expanded ( Fig. 2E View FIG ). Distal endings curving over the junction of the valve face and mantle ( Fig. 2D, F View FIG ). Internal valve view ( Fig. 3 View FIG ) shows striae separated by distinct virgae ( Fig. 3A, B View FIG ). Distal raphe endings terminate in small helictoglossae which are slightly angled towards the ventral margin ( Fig. 3C, E View FIG ), proximal raphe endings simple and curved abruptly towards the dorsal margin ( Fig. 3D View FIG ). In external girdle view ( Fig. 4 View FIG ), the cingulum is composed by 2-3 open bands or copulae. Mantle of each valve contains single row of areolae on both dorsal ( Fig. 4A, C, D View FIG ) and ventral side ( Fig. 4B View FIG ).