Chrysomorula cohaerens Wujek, 2013

Wujek, Daniel E., 2013, A new freshwater chrysophyte, Chrysomorula cohaerens gen. et sp. nov. (Chrysophyceae, Chrysocapsaceae) from North America, Phytotaxa 93 (2), pp. 61-64 : 62

Chrysomorula cohaerens Wujek sp. nov. ( Figs. 1–4 )

Cells are spherical to irregular (somewhat square) by mutual compression, 5.8–6.2 µm in diameter in face view, up to 7 µm long, somewhat in groups of four. Cells possess 1–4 pseudocilia 92–136 µm long. There are one or two goldenbrown (or less commonly yellow-green) parietal chloroplasts per cell. A chrysolaminarin vesicle, median nucleus and anterior contractile vacuole are prominent cell features. Pseudocilia are stationary and extend to the periphery of the gelatinous matrix. Reproduction or statospore formation was not observed.

Type: — UNITED STATES. Maryland: under the ice in an ephemeral pond, east of Belcamp, Harford County, 39.4697° N, 76.2569° W. Sample collected by R. H. Thompson , February 1944. Fig. 1 . Typification of the new species is based on the illustrations hereby published, as it was impossible to preserve specimens showing the features attributed to the taxon ( McNeill et al. 2011, ICN art. 40.5) .

Etymology: —The species name cohaerens is from the Latin, meaning “adhering together”.

Remarks: —The genus is distinctive by the nature of its macroscopic colonial habit, with cells forming a hollow sphere embedded in a matrix, and with pseudocilia extending from each cell to the periphery of the matrix. New colonies are formed by the fragmentation of the parent colony, often producing plankton forms. Cell reproduction appears to occur by binary division. Although quite rare, I have observed it primarily epiphytic on Oedogonium , Microspora , Rhizoclonium , and occasionally Utricularia . Additional USA sites in which Chrysomorula was observed: An I-70 turnpike marsh, west of Lawrence, Douglas County, Kansas, May 1966 and Green’s Lake, Beaver Island, Charlevoix County, Michigan, May 1999.

Figures

FIGURES 1–4. Diagrammatic representation of Chrysomorula cohaerens colonies. Fig. 1: Mature colony within the gelatinous matrix. Fig. 2: Early stage of ball adhering cells. Fig. 3: Cells at periphery of a maturing colony. Fig. 4: A portion of adhering cells from a developing hollow colony. Scale bars: Figs. 1–2: 25 µm; Figs. 3–4: 10 µm