Campylodiscus fastuosus Ehrenberg, 1845

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 : 3

Campylodiscus fastuosus Ehrenberg Figs 13, 14, 16, 18–20

Syn: Campylodiscus thuretii Brébisson

C. simulans Gregory

Ref. illus: Peragallo & Peragallo 1897 –1908, pl. 57, figs 4–9 (as C. thuretii ); Choi & Noh 1987, figs 73–76; Guettinger 1989 2.09.01-1; López Fuerte et al. 2010, pl. 39, figs 10, 11 (as C. simulans ); Stidolph et al. 2012, pl. 21, fig. 14 and pl. 6, fig. 132 (the latter as C. thuretii )

Samples: GU66F-7A, GU66F-8, GU52Q-10a, GU52Q-2, GY44Y-13

Dimensions: 16–34 µm diam., central striae 14 in 10 µm

Diagnostics: Circular valves with two parallel lines of short striae along the apical axis. Small valves similar to Surirella scalaris Giffen (Figs 15, 17) ( Lobban et al. 2012, pl. 68, figs 5, 6; pl. 69, figs 1, 2), but differing in the marked narrowing of the infundibula such that the spaces between them become wider and with a single prominent rib reaching the central area, whereas in S. scalaris the infundibula taper only a little and leave a uniform space between them, without a prominent rib. Both have several spiny ridges over the infundibula on both sides of the raphe; those of C. fastuosus are less spiny in comparison.

Comments: The difference is hard to see in small specimens in LM, and we needed complete frustules ( Figs 16, 18 ) before being sure about C. fastuosus , which commonly co-occurred with S. scalaris in these Guam samples from farmer-fish territories. The LM image published in Lobban et al. 2012, pl. 68, fig. 4 as Surirella scalaris is in fact C. fastuosus and a true image is shown here in Fig. 15 for comparison. This has been corrected on the web page. See VanLandingham (1968) for synonymies.

Figures

Figures 16–21. Figs 16, 17. Comparison of frustules of Campylodiscus fastuosa (Fig. 16) and Surirella scalaris (Fig. 17) showing crossed orientation of valves in the former versus parallel orientation in the latter. (GU66F-7A, GU52P-5, respectively) (SEM). Fig. 18. Frustule of C. fastuosa (GU66F-7A) (SEM). Figs 19, 20. C. fastuosa internal valves faces of small and large cells (GU66F-7A) (SEM). Fig. 21. Cocconeis dapalistriata, sternum valve (GU44AU-2) (SEM). Scale bars = 5 µm.