Phylum: Charophyta   Family: Desmidiaceae

Xanthidium scrobiculatum (Scott & Grönblad) Stastny, Skaloud & Neustupa 2013

Named for the scobiculate wall-thickening in the centre of the semicells, as opposed to being granulate in similar species. A rare species found in Atlantic regions in oligo-mesotrophic, acidic waters.

References: 
Stastny, J., Skaloud, P., Langenbach, D., Nemjova, K. & Neustupa, J. (2013). Polyphasic evaluation of Xanthidium antilopaeum and Xanthidium cristatum (Zygnematophyceae, Streptophyta) species complex.
Scott, A.M. & Grönblad, R. (1957) New and interesting desmids from the southeastern United States