Ulnaria sinensis Bing Liu et D.M. Williams, 2017

Liu, Bing, Williams, David M. & Tan, Lin, 2017, Three new species of Ulnaria (Bacillariophyta) from the Wuling Mountains Area, China, Phytotaxa 306 (4), pp. 241-258 : 243-248

Ulnaria sinensis Bing Liu et D.M. Williams , sp. nov. ( Figs 2–29 )

LM: Cells forming colonies in bands; frustules connected by interlocking, linking spines ( Fig. 2 ). Frustules rectangular in girdle view ( Figs 2 , 3 ); during development cells lack regular structure and hence lack rectangular outline ( Fig. 3 ). Valves linear, with parallel margins, narrowing at both poles ( Figs 4–10 ), which become protracted to rostrate ( Figs 4–8, 10 ). Transapical axis 6–8 μm, apical axis 296–512 μm (n = 50), length-to-breadth ratio ca. 49–64. Sternum central, distinctive, regular, extending length of valve ( Figs 4–10 ). Striae broad, mostly parallel, radiating only at poles; 8–9 in 10 μm. With respect to the sternum, striae pattern relatively uniform, most situated opposite one another, others not so ( Figs 8–10 , arrows). A single rimoportula present at each pole ( Figs 8, 10 ). Central area absent ( Figs 4–7, 9 ).

SEM: Frustules forming colonies in bands, through interlocking linking spines ( Figs 11–13 , Figs 20–22 ). Frustule composed of epivalve and hypovalve, each with a set of closed girdle bands. For epivalve there is a valvocopula (B1) and three copulae (B2–B4) ( Figs 11– 13 ). For hypovalve there is a valvocopula (B6) and a copula (B5) ( Figs 11–13 ). Each band possessing a single row of poroids ( Figs 11–13 ) that bisects pars interior and exterior, located at mid-line of each girdle band ( Figs 20, 23 ). Valve face meets mantle at obtuse angle ( Figs 16–22 ). Valves with uniseriate striae situated opposite each other, equidistant from sternum, radiating at poles, continuing onto valve mantle ( Figs 16–20 ). Vimines form 5–8 apically elongated areolae either side of the valve sternum, 4–6 on the valve mantle ( Figs 20–22 ). Often, a tiny poroid present in the terminal mantle areola ( Figs 20–22 , arrows). Each areola externally covered by velum ( Fig. 19 ). A single rimoportula present at each pole, each a pair of simple extended lips, aligned within a shortened radiate stria ( Figs 16, 18–20 ). Two horn-like outgrowths located on the surface of each ocellulimbus, the latter composed of c. 30 pervalvar and 7–14 transapical rows of porelli ( Figs 19–22 ). Linking spines spatulate, situated at valve/mantle junction, each spine extending from a virga ( Figs 20–22 ). Spines attach valves face to face by interlocking ( Figs 11–13 , 20–22 ). Mantle plaques absent ( Figs 20–22 ). Internally, valves possessing parallel margins, with rostrate poles; striae uniseriate almost opposite each other, composed of 5–8 slightly apically elongated areolae that radiate at apices ( Figs 26, 29 ). Rimoportulae prominent, possessing bilabiate structure, lying almost parallel to the adjacent stria ( Figs 27, 29 ).

Type: — CHINA. Guizhou: Fanjing Mountain National Nature Reserve, the course of Heiwang river, near Mile Daochang , 27°49’10” N, 108°46’18” E, 494 m a.s.l., Bing Liu , 31 st December 2015, (holotype BM! 101838, illustrated in Figs 4, 8–10 , from the same specimen; isotype JIU! G201604 , illustrated in Fig. 5 , indicated on the slide) .

Etymology: —Named after China, where the species is found.

Ecology: —The following environmental parameters were measured in the field. Electric conductivity was 54.9 ± 1.4 μS/cm, pH was 7.6 ± 0.1, and water temperature was10.4 ± 0.1 °C. Since the diatom sample was scraped off the surfaces of stones and the water electric conductivity is below 100 μS/cm, Ulnaria sinensis can be considered an epilithic diatom characteristic of poor electrolyte content freshwaters.

Figures

FIGURE 2. Ulnaria sinensis sp. nov., girdle view, LM.A pole of a colony composed of four frustules (labeled F1 to F4). Scale bar = 20 μm.

FIGURES 3–10. Ulnaria sinensis sp. nov., LM. 3. Whole frustule attached to single valve, in girdle view. 4. Holotype specimen. 5. Isotype specimen. 6–7. Two different valves. 8–10. Details of Fig. 4, note misaligned striae (arrows). Scale bars = 50 μm (Figs 3–7), 20 μm (Figs 8–10).

FIGURES 11–13. Ulnaria sinensis sp. nov., girdle view, SEM. 11. One pole of a colony, note the complete frustule and its cingulum elements, especially the six closed girdle bands (labeled B1–B6). 12. The middle part of the colony, note the six girdle bands (labeled B1–B6). 13. The other pole, note the complete frustule and its cingulum elements, especially the six closed girdle bands (labeled B1–B6). Scale bars = 10 μm.

FIGURES 14–19. Ulnaria sinensis sp. nov., external view, SEM. 14. One apex of a valve, note the rostrate end. 15. The middle part of a valve, note the parallel both sides. 16. Magnification of the previous apex. 17. Magnification of the previous middle part, note the linking spines (arrows) and the alternate striae (double-head arrow). 18. Magnification of an apex. 19. One pole showing the ocellulimbus and the pore closing plates. Scale bars =10 μm (Figs 14, 15), 5 μm (Figs 16–18), 1 μm (Fig. 19).

FIGURES 20–23. Ulnaria sinensis sp. nov., SEM. 20. One pole of two valves showing the basal siliceous layer, note the tiny poroids located at the end of the striae on the mantles (arrows). 21–22. Two poles in girdle view showing the closed valvocopulae, note the spatulate linking spines and the tiny poroids located at the end of the striae on the mantles (arrows). 23. Part of one girdle band, note the closed nature and one row of pores locating in the middle. Scale bars = 5 μm.

FIGURES 24–29. Ulnaria sinensis sp. nov., internal views, SEM. 24. One pole of a vavle, note the rostrate end. 25. The middle part of a valve, note the parallel both sides. 26. The other pole. 25. Magnification of the previous pole. 26. Magnification of the previous middle part. 27. Magnification of the other pole, note the alternate striae. Scale bars =10 μm (24–26), 5 μm (27–29).