Stricosus cardinalii Lobban and Theriot, 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 : 37-40

Stricosus cardinalii Lobban and Theriot sp. nov. ( Figs 99–103 )

Holotype:— ANSP G.C. 20067

Isotype: — ECT 3569, GU44AI.

Type locality: —Gab Gab Beach, Guam (13° 25.57’ N, 144 °38.57’ E).

Material studied: —Wild and cultured Edward C. Theriot material isolated from the original collection: ECT 3569, epiphytes on macrophytes growing on coral reefs off Gab Gab Beach, Guam, USA (13° 25.57’ N, 144 °38.57’ E).

Description: —Lengths observed were 111.4–232.1 μm and widths were 5.0–8.8 μm. Virga densities were 38–39 in 10 μm. Valves were convex in the middle, linear to convex in the flanking regions, and usually weakly concave towards the end, often forming a capitate apex ( Figs 99–101 ). The sternum was prominent but evenly thin along the entire valve ( Fig. 99 ). The deeply sunken ocellulimbi were 12–14 pores wide and 5–10 pores tall, with pore spacing at 3–4 pores per 1 μm and typically overhung by two spines ( Fig. 102 ). The symmetrically shaped rimoportulae were oriented transapically, and each positioned about 2.3–2.7 μm from the end of each pole ( Fig. 103 ). The bilayered wall was covered with biseriate striae externally, and there was a single pore internally at the junction of the face and mantle. Girdle bands were open and without pores.

Remarks: —This species was recovered from the same material as that of S. harrisonii . There were 5 base pair differences in the psbC sequence ( S. cardinalii lacked rbcL sequence) and could be distinguished by subtle but constant differences in shape. Whereas S. harrisonii had continuously convex margins from the center to the apex giving it a javelin-like appearance, S. cardinalii had a more complex shape, being convex in the middle, more linear or even weakly concave in the flanking regions, always becoming weakly concave towards the end. We also recorded much larger specimens of S. harrisonii than of S. cardinalii, DNA sequences associated with the cultured strain from which DNA was extracted was previously reported as Hyalosynedra sp. HK 363 in Lobban et al. (2015). The same slide was selected as the type for both species, and a pair of specimens in proximity to one another, one of each species, were circled by diamond scribe.

Etymology: —This species was named in honor of André Cardinal, Canadian phycologist and diatomist, especially for his leadership in studies of the diatom flora of the St. Lawrence River estuary.

Figures

FIGURES 99–103. Stricosus cardinalii from cultured material (GUStick3). 99. LM. Margins strongly convex. 100. SEM of exterior whole valve.Margins strongly concave in flanking regions on one side of valve, linear on other.101. SEM of interior whole valve. Margins linear and converging in flanking region. 102. SEM detail of apex, exterior. 103. SEM detail of apex, interior.