Phylum: Charophyta   Family: Desmidiaceae

Spondylosium pulchellum (W. Archer) W. Archer 1861

First described and illustrated by Archer (1858: 253, pl. 21: 7) as Sphaerozosma pulchellum. Three years later Archer (1861: 72, pl. 3: 104) moved it to Spondylosium. A filamentous species that can break up into smaller parts, which can then be confused with Cosmarium species.
Cell dimensions: L: 9-15 µm; B: 8-14 µm; Is: 4-6 µm; Th: 7-8 µm; L/B: 1.00-1.16.
West, West & Carter (1923: 227) note “It seems to occur more abundantly in Ireland than in any other part of the British lakes.” In the Outer Hebrides this is a rare species occasionally found in acidic, oligotrophic, habitats.

References: 
Archer, W. (1858) Supplementary catalogue of Desmidiaceae found in the neighbourhood of Dublin with description and figures of a proposed new genus and of four new species.
Archer, W. in Pritchard, A. (1861). A history of infusoria, including the Desmidiaceae and Diatomaceae, British and foreign.
Coesel, P.F.M. & Meesters, K.J. (2023 second edition) Desmids of the Lowlands.
West, W., West, G.S. & Carter, N. (1923) A Monograph of the British Desmidiaceae, Volume 5.