Systematics of araphid diatoms with asymmetric rimoportulae or densely packed virgae, with particular attention to Hyalosynedra (Ulnariaceae, Bacillariophyta) Author Sabir, J. S. M. Genomic and Biotechnology Research Group, Department of Biological Sciences, Faculty of Science, King Abdulaziz University (KAU), Jeddah 21589, Saudi Arabia Author Theriot, E. C. Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA Author Lobban, C. S. Division of Natural Sciences, University of Guam, Mangilao, Guam 96923, USA Author Alhebshi, A. M. Genomic and Biotechnology Research Group, Department of Biological Sciences, Faculty of Science, King Abdulaziz University (KAU), Jeddah 21589, Saudi Arabia Author Al-Malki, A. L. Department of Biochemistry, Faculty of Science, KAU, Jeddah 21589, Saudi Arabia. Author Hajrah, N. H. Genomic and Biotechnology Research Group, Department of Biological Sciences, Faculty of Science, King Abdulaziz University (KAU), Jeddah 21589, Saudi Arabia Author Khiyami, M. A. King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia. Author Obaid, A. Y. Department of Chemistry, Faculty of Science, KAU, Jeddah 21589, Saudi Arabia. Author Jansen, R. K. Genomic and Biotechnology Research Group, Department of Biological Sciences, Faculty of Science, King Abdulaziz University (KAU), Jeddah 21589, Saudi Arabia & Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA Author Ashworth, M. A. Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA text Phytotaxa 2018 2018-04-10 347 1 1 49 http://dx.doi.org/10.11646/phytotaxa.347.1.1 journal article 10.11646/phytotaxa.347.1.1 1179-3163 13707999 Stricosus alfageehii Sabir and Theriot sp. nov. ( Figs 78–82 ) Holotype :— ANSP G.C. 38102 Isotype : — KSA 0128 in the Theriot Collection at UT Austin. Type locality: —Obhur shoreline, near Jeddah, Makkah Province , Saudi Arabia ( 21° 43.535’ N , 39° 06.949’ E ). Material studied: —Wild and cultured ( UTKSA 0077) material, isolated from type locality: SA 29, sediment collected from the submerged rocky bottom at the Obhur area of Jeddah, Kingdom of Saudi Arabia ( 21° 43.535’ N , 39° 06.949’ E ). Wild and cultured ( KSA 0128) material, isolated from collection: SA 12, plankton tow collected from the breakwater at the Al Qatan Resort at Markaz Al Shoaibah, Kingdom of Saudi Arabia ( 20° 50.47’ N , 39° 24.05’ E ). Wild and cultured ( UTKSA 0242) material, isolated from collection: KSA 2015-14, sediment collected from the submerged rocky bottom at the Obhur area of Jeddah, Kingdom of Saudi Arabia ( 21° 43.535’ N , 39° 06.949’ E ). FIGURES 73–77. Thalassionema cf. nitzschioides from culture HK360. 73. Exterior, whole valve. 74. Exterior, right facing apex from 73. 75. Exterior, left facing apex from 73. 76. Interior, whole valve. 77. Interior, detail of apex. FIGURES 78–82. Stricosus alfageehii from wild (SA29; 78, 79) and cultured (KSA0128; 80–82) material. 78. LM of whole large valve. 79. LM of smaller whole valve. 80. SEM of larger whole valve. 81. SEM detail of exterior of apex. 82. SEM detail of interior of apex. Description: —Valves were 41.5–185.8 μm long by 3.4–10.7 μm wide. The sternum was narrow and linear. Virga densitites of 38–44 per 10 μm. External pores were barely resolvable; striae were biseriate. The bilayer wall was open to the interior via a single pore at the junction of the face and mantle. A rimoportula was positioned about 1.9–3.0 μm from each end of the valve. The deeply sunken ocellulimbus was overhung by two spines, 9–14 pores wide and 7–10 pores tall, with about 4–7 pores per 1 μm. Girdle bands were open and without pores. Remarks: — Stricosus alfageehii and S. madanii , described below, were found in the same sample. Whereas S. madanii had margins that were parallel for roughly half of more of the length, the margins of S. alfageehii were generally weakly convex in the middle, then either convex or linear in the flanking regions, with the outline progressively becoming linear as it approached the apex. The rimoportula opening of S. alfageehii was observed to be linear; that of S. madanii was sinuous. Etymology: —This species was named in honor of Dr. Mohamed B. Alfageeh, Director, National Centre for Biotechnology, King Abdulaziz City for Science and Technology (KACST), Riyadh 11442, Kingdom of Saudi Arabia .