Rhoicosigma compactum (Greville) Grunow, 1877

Lobban, Christopher S., 2015, Benthic marine diatom flora of Guam: new records, redescription of Psammodictyon pustulatum n. comb., n. stat., and three new species (Colliculoamphora gabgabensis, Lauderia excentrica, and Rhoiconeis pagoensis), Micronesica 2015 (2), pp. 1-49 : 14-15

publication ID

https://doi.org/ 10.5281/zenodo.12117576

DOI

https://doi.org/10.5281/zenodo.12117598

persistent identifier

https://treatment.plazi.org/id/03826143-FF96-8177-FF34-F9C71646F82C

treatment provided by

Felipe

scientific name

Rhoicosigma compactum (Greville) Grunow
status

 

Rhoicosigma compactum (Greville) Grunow Figs 139–143 View Figures 139–149

Ref. illus.: Van Heurck 1896, pl. 28, fig. 802; Peragallo & Peragallo 1897 –1908, pl. 35, fig. 8 Sample GU52N-7, GU52O-3; GU52P-1

Dimensions: Length 97–118 µm, width 16–23 µm, striae 20–22 in 10 µm.

Diagnostics: Frustule bent along the valvar plane (achnanthoid) ( Fig. 139 View Figures 139–149 ); raphe on concave/ventral valve highly sigmoid, the other (convex valve) nearly straight (as for the genus) ( Figs 140, 141, 143 View Figures 139–149 ). Plastids are several large plates ( Fig. 139 View Figures 139–149 ). Central raphe endings overlap on both valves ( Fig. 142 View Figures 139–149 ).

Comments: Hein & Lobban (2015) included two SEMs of this species for comparison with their new species R. parvum . Here I present full documentation of the record. Peragallo & Peragallo (1897 –1908) gave length = 77–180 µm, whereas Van Heurck (1896) gave rather larger dimensions of 140–180 x 35 µm, both gave stria density of 20–24 in 10 µm for R. compactum . R. oceanicum H. Peragallo ( Peragallo & Peragallo 1897 –1908, pl. 35, figs 3–7) is still larger (160–260 x 36– 45µm), with still coarser striae (17–18 in 10 µm). Hendey (1964, p. 250) gives dimensions of R. compactum as 90–150 µm, transapical striae 17–20 in 10 µm, longitudinal striae 22–24 in 10 µm, but he cites Peragallo & Peragallo (1897 –1908) figs 3, 4, 6, 7 and 8, whereas their figs 3–7 are identified as R. oceanicum .

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