Biddulphiella tridens (Ehrenberg) Ashworth & Sims

Lobban, Christopher S. & Witkowski, Andrzej, 2023, Marine benthic diatoms of Guam: new records, Dictyoneis apapae sp. nov., and updates to the checklist, Micronesica 2023 (2), pp. 1-75 : 6

Biddulphiella tridens (Ehrenberg) Ashworth & Sims Figs 26–29

Syn.: Biddulphia tridens (Ehrenberg) Ehrenberg

Biddulphia tuomeyi (J.W. Bailey) Roper

Ref. illus.: Schmidt et al. 1874–1959, pl. 118, figs 1–7 and pl. 119, figs 1–6; Peragallo & Peragallo 1897 –1908, pl. 94, fig. 2; Hustedt 1927 –1930, fig. 491; Navarro 1981, fig. 15; Lobban & Jordan 2010, fig. 5q, 5r (all as B. tuomeyi ); López Fuerte et al. 2010, pl. 12, figs 6–7; Ashworth et al. 2013, figs 5b, 5i; Sims et al. 2023, fig. 13

Samples: GU7Y-4

Dimensions: Length 42–63 µm, width 27–30 µm

Diagnostics: Deeply sculpted valve in girdle view, central dome flanked by two smaller ones that abut or are themselves separated from the tall pseudocellus-bearing horns on the two poles. Many spines on the domes and the central dome with two rimoportulae with very long external tubes. The deep grooves (sulci) ( Fig. 29 ) were used to distinguish Biddulphiella from Biddulphia ( Sims et al. 2023) .

Comments: Differs from Biddulphia biddulphiana (J.E.Smith) Boyer ( Navarro & Lobban 2009, figs 28–31) in the more elongate, rostrate valve outline and number of domes. VanLandingham (1968, p. 562) commented on which specific epithet had priority and listed the extensive synonymy under B. tridens .

Figures

Figures 26–31. Biddulphiella and Biremis. Figs. 23–26. Biddulphiella tridens. Fig. 26. Frustule in valve view at two focal planes. Figs 27, 28. Valves in girdle and valve view, respectively, SEM. Fig. 29. Valve in oblique view, emphasizing the deep grooves (sulci) between the elevations. Figs. 30, 31. Biremis ambigua frustules in SEM. Fig. 30. Oblique view showing raphe and paired external alveolus openings. Fig. 31. Broken frustule showing internal side of alveoli (arrow) and exterior of girdle bands. Scale bars = 10 µm.