Encyonopsis horticola Van de Vijver & Compère

Kennedy, Bryan, Buckley, Yvonne & Allott, Norman, 2019, Taxonomy, ecology and analysis of type material of some small Encyonopsis with description of new species in Ireland, Phytotaxa 395 (2), pp. 89-128 : 113

Encyonopsis horticola Van de Vijver & Compère ( Figs 397–404 )

Description: Valves are moderately dorsiventral, lanceolate to elliptic-lanceolate but never linear lanceolate. Clearly convex dorsal margin and slightly convex ventral margin. Apices are slightly protracted, broadly rounded, rostrate to subrostrate but never capitate to subcapitate. Valve dimension almost equivalent to type population from a limited number of valves examined. Length 11–15.8 μm; width 2.9–3.5 μm; maximum L:W ratio 5.1. Axial area is very narrow and central area almost absent. Striae are clearly radiate with a clear shift in orientation and with shortened dorsal and ventral stria at valve centre. Stria density 27–30 dorsally and 26–28 ventrally in 10 μm. All other characteristics equivalent to that given with type diagnosis.A slight gap in internal proximal raphe endings illustrated in Van de Vijver & Compère ( Fig. 43 ) is concealed under a silica flap in Irish population.

Ecology: Few documented records for this taxon exist in natural waterbodies in Europe since it was first described from a small pool in the national botanic garden of Belgium. A single population at low relative abundance (3.3%) occurs in L. Gur, Co. Limerick. This lake is mesotrophic to eutrophic (mean TP= 0.03 mg /l-P; max. chlorophyll- a =24μg/l) and at poor ecological status when last classified for the WFD.

Figures

FIGURES 397–404. Encyonopsis horticola Van de Vijver & Compère Figs 397–402. LM. Figs 397–402. Valves showing morphological range of a single population in L. Gur, Co. Limerick. Figs 403–404. SEM. Fig 403. External view. Fig. 404. Internal view. Scale bar in Fig. 402 = 10 μm for all LM figures. Scale bar in all SEM micrographs = 1 μm.

FIGURES 29–71. Encyonopsis hibernica sp.nov.Figs 29–60.LM.Fig.44.Holotype specimen.Figs 29–60.Valves showing morphological range and size variation in several populations. Figs 61–71. SEM. Fig. 61. External view. Fig. 62. Internal view. Figs 63–71. Variation in valve outline. Scale bar in Fig. 60 = 10 μm for all LM figures except holotype specimen. Scale bar in all SEM micrographs = 1 μm and = 2 μm in Figs 65–70.