Monoraphidium subclavatum Nygaard 1977

Yoon, Sung Ro & Lee, Do Hyun Kim and Ok-Min, 2020, Newly recorded chlorophytes, Monoraphidium subclavatum, Deuterostichococcus epilithicus, and Pseudostichococcus monallantoides in Korea, Journal of Species Research 9 (3), pp. 181-190 : 184-185

Monoraphidium subclavatum Nygaard 1977 ( Fig. 1 )

Cells are solitary, spindle-shaped, slightly or moderate crescent-shaped, rarely sigmoid, with both ends gradually tapering to a point, but not in long tips. Chloroplast covers almost the entire cell wall, and is not clearly confined to the center, without a pyrenoid. Propagation is mostly achieved by four autospores, which are slightly crescent-shaped in young cells, but increasingly crescent eventually. The cell length is 13.7 - 22.2 μm and width is 2.4 - 5.3 μm.

Note. Spindle-shaped and slightly crescent-shaped cells were mainly observed. The ends of the cells are pointed, but the ends are shorter and the blunt ends differ from those of M. pusuillum (Printz) Komárková-Legnorová. Individuals measuring 14 - 16 μm in length appeared frequently. Phylogenetic analyses using 18S rDNA sequences showed that the genus Monoraphidium is polyphyletic, and Monoraphidium subclavatum formed the same clade with Messastrum gracile . However, the two species are distinguished by cell curvature and colony formation.

Ecology. This is a freshwater species. They inhabit small water biotopes ( Komárek and Fott, 1983). This species was collected from planktonic samples of a eutrophic river.

Site of collection. Joochun river , Hoengseong-gun, Gangwon-do (37°24′44.4″N 128°09′20.0″E) .

Date of collection. May 28, 2019.

Specimen Locality. FBCC-A 409 in the Nakdonggang National Institute of Biological Resources.

Figures

Fig. 1. Microscopic photographs of Monoraphidium subclavatum Nygaard FBCC-A409. (A, B) spindle-shapes, (C-H) slightly and moderate crescent-shapes, (I-L) autospores in the mother cell. Scale bar represents 10μm.