Hyalosynedra sublaevigata Álvarez-Blanco and S. Blanco

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 : 16

Hyalosynedra sublaevigata Álvarez-Blanco and S. Blanco ( Figs 20–26 )

Material studied: —Wild material ( ECT 4119) from 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: —Valves were 28.6–92.1 μm long and 2.5–5.3 μm wide ( Figs 20–22, 25 ). Outlines were lanceolate: convex in the middle and either linear to weakly convex in the flanks narrowing towards the apices. The ends either continued to converge, or exhibited a weak concave reflex. Each sternum was lanceolate (thicker in the middle than at the apices of the valve: Figs 20, 21, 23, 24 ). Striae were biseriate. Virgae were densely packed (50–54 in 10 μm). An asymmetric rimoportula occurred at each pole ( Figs 23, 24, 26 ). Girdle bands were dissociated from one another and the valves in the cleaned cultured material, but all girdle bands found in the cultured material were without pores and all were open (not illustrated).

Remarks: —Our Puerto Rican specimens overlapped in measurements reported for Mediterranean Sea type material (26.5–34.1 μm long, 2.3–3.0 μm wide, Álvarez-Blanco & Blanco 2014), and had the same valve outline and lanceolate sternum. Both had asymmetric rimoportulae, and ocellulimbi were of the same dimensions (6–8 pores wide by three high). Girdle band morphology was not reported for the type, so no comparison between our material and the type material is possible.

Figures

FIGURES 20–26. Hyalosynedra sublaevigata from HK512, Puerto Rico. 20. LM of specimen with somewhat protracted or weakly concave margin before capitate end. 21. LM of specimen with margin concave to capitate end. 22. SEM of specimen with margins near linear from center to end. 23. SEM detail of apex. 24. SEM detail of broad central area of lanceolate sternum. 25. SEM interior of entire valve. 26. SEM detail of interior of apex showing asymmetrical rimoportula.