Thalassiosira nanolineata (A. Mann) Fryxell & Hasle, 1977

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 : 16

Thalassiosira nanolineata (A. Mann) Fryxell & Hasle Figs 104–106

Ref. illus.: Mann 1925, p. 68, pl. 14, fig. 4; Fryxell & Hasle 1977 p. 32, figs. 74–80; Sar et al. 2002 Table 1 ; Y. Li et al. 2013, p. 99, figs 89–94; J.S. Park et al. 2016, p. 414, fig. 28

Samples: GU44Z-15, GU52P-9

Dimensions: 12.8–19.8 diam., areolae 8–9 in 10 µm

Diagnostics: Areolae linear, not radial, single row of fultoportulae around the margin, their external part ending in a cuplike structure with a central post. Rimoportula inserted between two fultoportulae (rather than replacing one). Two central fultoportulae.

Comments: Although the areolar density is lower than most records (Y. Li et al. 2013 the exception), these specimens seem to agree with the modern concept of the species originally described from the Philippines by Mann (1925). The surveys of Thalassiosira diversity in Argentina ( Sar et al. 2002), Guangdong Province, China (Y. Li et al. 2013), and South Korea (J.S. Park et al. 2016) are all very helpful in identifying the species here.

Figures

Figures 98–106. Stricosus and Thalassiosira. Figs 98–103. Stricosus harrisonii. Figs 98, 99. Living cells showing plastids with pyrenoids. Figs 100, 101. Acid cleaned valves in LM and SEM. Fig. 102. External apex showing triangular hyaline area, two spines, rimoportula opening, and ocellulimbus with at least 7 rows of pores (contrast Fig. 62, Hyalosynedra). Fig. 103. Apex internal view showing symmetrical rimoportula (arrow). Figs 104–106. Thalassiosira nanolineata. Fig. 104. Valve in LM at two focal planes. Fig. 105, 106. External and internal aspects in SEM, showing central fultoportulae (F) and rimoportula (R) (arrows). Scale bars: Figs 98, 100, 101 = 20 µm, Fig 104 = 10 µm, Figs 99, 103, 105, 106 = 5 µm, Fig. 102 = 2 µm.