Phylum: Chlorophyta   Family: Hydrodictyaceae

Pseudopediastrum cornutum (M. Raciborski) J. Lenarczyk 2020

First described and illustrated by Raciborski (1889: 111, pl. 2: 38) as Pediastrum duplex var. cornutum. After various nomenclatural reassessments it was recently raised to species rank by Lenarczyk (2020: 1572, fig. 2 e-f). It differs mainly in having irregularly-shaped intercellular spaces.
Coenobia spherical with 8-128 cells: diameters: 60-320 µm. Marginal cells: 24-27 µm across.
Less frequent than P. boryanum. but found in similar habitats: lochs, ponds, etc. Considered an indicator of mildly enriched waters.

References: 
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition). The Freshwater Algal Flora of the British Isles.
Lenarczyk, J., Saluga, M. & Piatek, J. (2020). Integrative approach helps clarify confusing taxonomy of the Pseudopediastrum boryanum species complex (Chlorophyceae), including recognition of five distinct species.
Raciborski, M. (1889 '1890'). Przeglad gatunków z rodzaju Pediastrum.