Stricosus navarroensis Theriot and Ashworth, 2018

Sabir, J. S. M., Theriot, E. C., Lobban, C. S., Alhebshi, A. M., Al-Malki, A. L., Hajrah, N. H., Khiyami, M. A., Obaid, A. Y., Jansen, R. K. & Ashworth, M. A., 2018, Systematics of araphid diatoms with asymmetric rimoportulae or densely packed virgae, with particular attention to Hyalosynedra (Ulnariaceae, Bacillariophyta), Phytotaxa 347 (1), pp. 1-49 : 32-34

Stricosus navarroensis Theriot and Ashworth sp. nov. ( Figs 90–94 )

Holotype:— ANSP G.C. 30926

Isotype:— ECT 4119.

Type locality: —subtidal sediments and benthic scrapings collected near the Caribe Hilton at Condado Lagoon, San Juan, Puerto Rico (18° 27.6’ N, 66 °5.1’ W).

Material studied: —Wild and cultured (PR1 “synedroid P1”) material collected from the type locality: ECT 4119, subtidal sediments and benthic scrapings collected near the Caribe Hilton at Condado Lagoon, San Juan, Puerto Rico (18° 27.6’ N, 66 °5.1’ W).

Description: —Specimens observed ranged in size from 46.9–151.4 μm long and 3.5–5.1 μm wide, with densely packed virgae (49–50 in 10 μm). Each specimen had a narrow, lanceolate sternum ( Figs 90–93 ). Valves were convex in the middle, transitioning to weakly convex or linear along the flanks, with the margins of most apices convergent ( Figs 91–94 ) or tapering together, and were only rarely subcapitate ( Fig. 90 ). Ocellulimbi were deeply sunken, 3–4 pores tall and 6–12 pores wide, and were overhung by 5–6 spines. There was a rimoportula at each pole, with symmetrical coverings that were slightly oblique to the transapical axis, and being about 2.0–2.2 μm from the end of the valve. The external opening of the rimoportula was a slit-like pore. The striae were biseriate. The walls were bilayered with a single pore internally per chamber. The girdle bands were smooth and open.

Remarks:— The type slide was also the source for our observations on H. sublaevigata , which was similar in morphology, but whose sternum was generally prominently lanceolate and whose pore field was about twice as wide as measured by the number of pores.

Etymology:— Named to honor Dr. Nelson Navarro and his many contributions to our understanding of diatom diversity in nearshore marine habitats, especially on coral reefs.

Figures

FIGURES 90–92. Stricosus navarroensis from wild (ECT4119) material. 90. LM of smaller specimen. 91. SEM of whole valve. 92. SEM of apex.

FIGURES 93, 94. Stricosus navarroensis from cultured (PR1) material. 93. Interior whole valve. 94. Interior detail of apex.