Plagiogramma minor (W.Gregory) Chunlian Li, Ashworth & Witkowski

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 : 12-13

Plagiogramma minor (W.Gregory) Chunlian Li, Ashworth & Witkowski Figs 85, 86

Basionym: Denticula minor W.Gregory

Ref. illus.: Kaczmarska et al. 2017, p. 27, figs 13A–D.

Samples: GU52O-4, GU52X-5 (biofilm on calcareous sand)

Dimensions: Length 11–12 µm, width 5 µm; striae 17 in 10 µm

Diagnostics: rhomboidal valves with central elevation and two elevated apical pore fields; large flaps on the four most-apical spines.

Comments: Kaczmarska et al. (2017) compared their specimens to similar species and concluded that there was no match. Our specimens are very close to their fig. 13A. In their nomenclatural note, Kaczmarska et al. claimed that the correct epithet is minus, since Dimeregramma is a neuter noun, and Li et al. (2020, p. 13) used this transferring the species to Plagiogramma (also neuter). However, minus is an adverb and the correct adjective here is minor , which has the same ending across all genders in the nominative singular ( Stearn 1973), as used by Gregory (1857) in the basionym.

Figures

Figures 81–86. Parlibellus and Plagiogramma, SEM except Fig. 81. Figs 81–84. Parlibellus biblos. Fig. 81. Live cell showing plastids. Fig. 82. General view of portion of valve. Fig. 83. Detail of apex showing concentric circles of areolae around the raphe ending. Fig. 84. Detail of interior showing the stauros as a transverse bar not visible from outside. Figs 85, 86. Plagiogramma minor in girdle and valve view. Scale bars: Figs 81, 82 = 10 µm, Figs 84, 85, 86 = 5 µm, Fig. 83= 2 µm.