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 madanii Sabir and Theriot sp. nov. ( Figs 104–111 ) Holotype : — ANSP G.C. 38101 Isotype : — UTKSA 0065 Type locality: —Obhur near Jeddah, Makkah Province , Saudi Arabia ( 21° 43.535’ N , 39° 06.949’ E ). Material studied : Wild and cultured ( UTKSA 0065, KSA 0171) 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 ). FIGURES 104–107. Stricosus madanii from wild (SA29) material showing range in variation in shape. 104. Large specimen with parallel linear sides. 105. Large specimen with concave sides. 106. Small specimen with parallel linear sides. 107. Small specimen with concave sides. FIGURES 108–111. Stricosus madanii from cultured material (KSA0171). 108. Disassociated frustule showing interior of valve (top), unornamented girdle bands (middle) and exterior of valve (bottom). 109. Detail of apex of valve and associated girdle bands. 110. Interior of specimen with more strongly converging margin at apex. 111. Interior detail of specimen with less strongly converging apex. Description: —Valves of this robustly shaped species were observed to be 51.9–137.4 μm long and 6.1–9.2 μm wide. Sides were parallel for much of the valve length for most valves; a few valves were even slightly concave in the middle, widening towards the poles ( Figs 104–108 ). Margins became slightly convex towards the apices and converged to a rounded end. Apices were never observed to be capitate. The sternum was prominent but evenly thin along the length of the valve ( Figs 104–107 ). Virga spacing was visible in the LM, more prominently than on the valves of most other species, and was measured at 40–43 in 10 μm. The deeply sunken ocellulimbi were 6–14 pores wide and 6–8 pores tall, and overhung by 1–3 spines ( Fig. 109 ). The specimens had a rimoportula at each pole with unusual internal morphology. The covers bordering the aperture were elongated and oblique to the transapical axis, but the slit and covers were sinuous ( Figs 110, 111 ). The external rimoportula pores were about 1.6–2.4 μm from the end of the valve ( Fig. 109 ). Striae were biseriate and walls were bilayered, again with a single pore internally. Girdle bands were open and without pores ( Fig 109 ). Remarks: —Unlike other the species studied here, S. madanii has a very distinct outline and robust appearance, and was relatively wide for its length. The sinuous rimoportula lips and slit were also unique among diatoms studied. Etymology: —Named in honor of Prof. Dr. Ghazi Obaid Madani, Former President of King Abdulaziz University (KAU), Jeddah, Saudi Arabia , for his contributions to scientific research.