Auricula densistriata Osada, 1997

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 : 4

Auricula densistriata Osada Figs 8, 9

Lobban et al. (2012) reported A. complexa (Gregory) Cleve from Guam, but J.S. Park et al. (2018) noted that the valve size and stria density of the voucher specimens match Auricula densistriata K. Osada ( Osada 1997) . Stria density for A. complexa is 15–20 in 10 µm ( Peragallo & Peragallo 1897 – 1908), but Lobban et al. reported 26–28 in 10 µm. In SEM ( Figs 8, 9 ) we measured 27 striae. Auricula complexa species was correctly reported from Federated States of Micronesia — Yap by Navarro & Lobban (2009) and Chuuk by Park et al. (2022) —and may well be present in Guam but we have no evidence of it, so for now remove it from the flora.

Figures

Figures 8–14. Auricula and “Bacillaria.” Figs 8, 9. Auricula densistriata. Figs. 10–14. “Bacillaria Group B” sensu Schmidt, var. tumidula. Fig. 10. Acid cleaned frustules in LM. Fig. 11. Live cell. Fig. 12. Internal valve surface, SEM. Fig. 13. Wider central part of cell in SEM, showing external short cristae (arrow). Fig. 14. Apex of frustule in SEM showing the raphe flap (arrow) that links cells together and girdle bands. Scale bars: Fig. 11 = 25 µm, Fig. 10 = 10 µm, Figs 8, 9, 12–14 = 5 µm.