Pleurosira indica Karthick & Kociolek, 2011

Karthick, B. & Kociolek, J. P., 2011, Four new centric diatoms (Bacillariophyceae) from the Western Ghats, South India, Phytotaxa 22 (1), pp. 25-40 : 27-29

publication ID	https://doi.org/ 10.11646/phytotaxa.22.1.2
DOI	https://doi.org/10.5281/zenodo.4776677
persistent identifier	https://treatment.plazi.org/id/03E387EA-557B-FFBD-A6E9-FE38A470FA97
treatment provided by	Felipe
scientific name	Pleurosira indica Karthick & Kociolek
status	sp. nov.

Treatment

Pleurosira indica Karthick & Kociolek , sp. nov. ( Figures 1–2 View FIGURE 1 View FIGURE 2 ; holotype illustrated in Fig. 1–B View FIGURE 1 )

Valvae circularae ad ellipticae 31.6–77.4 µm diametro. Superficies valvarum dilute hemisphaerica. Ocelli 2 raro 3, nondiligenter oppositi sibi. Rimoportulae 3–7, expansa super valvam. Sulcus circularis circa rimpoportulam. Striae radiatae 14–18/ 10 µm ad marginem. Areolae in seriebus brevibus radialibus ad marginem in parte centrali irregulariter disposita valvae, 13–18/ 10 µm. Spinulae praesentes super superficiem valvae.

Valves circular to elliptical, 31.6–77.4 µm in diameter. Valve face slightly hemispherical. Ocelli 2, rarely 3, and ocelli not exactly opposite one another. Rimoportulae 3–7 spread across valve. Circular groove present around rimoportula. Striae radiate 14–18/ 10 µm at margin of valve face. Areolae in short radial rows at margin, irregularly arranged in central part of valve, density ranging from 13–18 in 10µm. Spinules present across valve face.

Type:— Kodaikanal Lake (10°14’03” N, 77°29’13”E, altitude 2090 meters above sea level), Dindigul District , Tamil Nadu, Collected by Dinesh Kumar , 22 nd December 2008 (holotype CESH-5-1881, Centre for Ecological Science Herbarium Diatom Collection , Indian Institute of Science, Bangalore, INDIA; isotypes BM 101457) GoogleMaps .

Habitat: —Sample collected from a floating aquatic plant. This species occurs in slightly acidic water (pH: 6.25±0.12) with phosphates 0.06± 0.02 mg l -1; nitrates: 0.55± 0.13 mg l -1 and dissolved oxygen 3.95± 0.55 mg l-1.

Distribution: —Currently known only from the type locality.

Etymology: —Named after the country name, India.

Observations: —In the SEM the valve has irregular areolae that occur across the face ( Figs 2–A, B, C View FIGURE 2 ) and extend onto the mantle ( Fig. 2–E View FIGURE 2 ). Two, rarely three ( Fig. 2–B View FIGURE 2 ) ocelli are present. Ocelli are ellipticalelongate in shape and the porelli that comprise the ocelli are small and radiate in their organization ( Figs 2–A, B, F View FIGURE 2 ). Internally, ocelli appear as depressions at the valve face/mantle junction ( Figs 2–C, D View FIGURE 2 ). Rimportulae have round openings externally ( Figs 2–A, B View FIGURE 2 ). Internally they are elevated and lip-like ( Figs 2–G, H View FIGURE 2 ). There is a c–shaped depression around the rimportula internally (Fig. H). The girdle is wide, and copulae possess distinct pores.

Pleurosira indica differs from P.laevis (Ehrenb.) Compère by the presence of irregularly arranged areolae and presence of c–shaped depression around the rimoportulae. Pleurosira laevis ( Fig. 1 View FIGURE 1 in Compère 1982, Fig. 2–A View FIGURE 2 in Kociolek et al. 1983) shows a clear pattern in areolae arrangement with striae radiating from the centre to margin and a silica surface which separate the porelli from areolae ( Fig. 4 in Compère 1982) is also absent in P. indica . Pleurosira indica can be easily distinguished from P. soctrensis var. pangeroni Compère (Figs 33–36, 44 in Compère 1982) by valve outline and absence of a c–shaped depression around each rimportula. Pleurosira soctrensis var. pangeroni has also been reported from South India ( Compère 1982). Pleurosira indica also differs from another Indian taxon, Pleurosira socotrensis var. bengalensis Compère (Figs 37, 38, 44 in Compère 1982), by the absence of the 6–15 labiate processes being arranged in a circular fashion.