Ulnaria gaowangjiensis 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 : 253-255

Ulnaria gaowangjiensis Bing Liu et D.M. Williams , sp. nov. ( Figs 52–71 )

LM: Frustule rectangular in girdle view, shallower towards centre ( Fig. 58 ). Valves linear-lanceolate, with protracted rostrate ends ( Figs 52–57 ). Valves linear, with parallel margins, tapering dramatically towards the poles ( Figs 52–57 ). Internal view of valve differs slightly from external view as slender rostrate poles become visible (compare Figs 52, 53, 56 to Figs 54, 55, 57 ). Transapical axis 6.5–8.5 μm, apical axis 61–108 μm (n = 50). Sternum central, distinctive, regular, extending length of valve. Striae broad, parallel, radiating only at poles, 9–11(often 10) in 10 μm. Striae parallel throughout valve, most opposite either side of sternum, some not so ( Figs 52–57 , arrows). Single rimoportula present at each pole, central area more or less square ( Figs 52–57 ).

SEM: Frustule rectangular in girdle view, shallow towards centre ( Fig. 59 ). Each frustule composed of epivalve, hypovalve and a set of girdle bands. The epivalve has three closed bands, a valvocopula and two copulae ( Figs 60–62 , B 6–B4 ), as for hypovalve ( Figs 60–62 , B 1–B 3 ). Each girdle band possessing a single row of poroids along its centre ( Figs 60–62 ). Valve face and mantle meet almost at right angles ( Figs 59–62 ). Valves with biseriate striae, most situated opposite each other, equidistant until radiating at the poles, extending to valve-mantle border, then continuing onto mantle ( Figs 59–62 , 64–66 ). Each stria composed of two rows of alternate poroids; near sternum the two rows often merge becoming a single row ( Figs 64–66 , arrows). Each areola (including those on mantle) covered externally by velum ( Fig. 67 ). A single rimoportula present at each pole, each as pair of simple extended lips, situated on sternum ( Figs 64–66 ). Two horn-like outgrowths located on top of each ocellulimbus ( Figs 59, 60, 62 ). Mantle plaques present ( Figs 60–62 , arrows). Internally, valves linear-lanceolate, with rostrate poles; striae biseriate almost opposite each other, near sternum becoming uniseriate ( Figs 69–71 ). Rimoportulae prominent, possessing characteristic bilabiate shape, lying well into pole ( Figs 69, 71 ).

Type: — CHINA. Hunan: Gaowangjie National Nature Reserve, the course of Maxi stream, near the building of Maxi village committee, 28°41’27” N, 110°3’60” E, 407 m a.s.l., Bing Liu , 19 th March 2016, (holotype BM! 101840, illustrated in Fig. 53 ; isotype JIU! G201606 , illustrated in Fig. 56 , in both cases the specimens are indicated on the slide) .

Etymology: —Named after Gaowangjie National Nature Reserve, where the species was found.

Ecology:— The following environmental parameters were measured in the field. Electric conductivity was 38.9 ± 0.4 μS/cm, pH was 8.5 ± 0.1, and water temperature was13.8 ± 0.4 °C. Since the diatom sample was scraped off the surfaces of stones and the water electric conductivity is below 50 μS/cm, Ulnaria gaowangjiensis can be considered an epilithic diatom characteristic of low electrolyte content freshwaters.

Figures

FIGURE 1. Map of the study sites: FR = Fanjing Mountain National Nature Reserve, GR = Gaowangjie National Nature Reserve, ZP = Zhangjiajie National Forestry Park.

FIGURES 52–58. Ulnaria gaowangjiensis sp. nov., LM. 52–58. Six valve showing variety of the valve, note some striae without opposite ones (arrows). 52. External view of a valve. 53. Photograph of holotype. 54–55. Internal view of two valves. 56. Photograph of isotype. 57. One whole frustule in girdle view. Scale bar =10 μm for all figures.

FIGURES 59–62. Ulnaria gaowangjiensis sp. nov., girdle view, SEM. 59. One complete frustule. 60–62. Details of the previous whole frustule, note the cingulum elements, especially the six closed girdle bands (labeled B1–B6) and plaques (arrows). Scale bar =10 μm (Fig. 59), 5μm (Figs 60–62).

FIGURES 63–67. Ulnaria gaowangjiensis sp. nov., external view, SEM. 63. One whole valve. 64–66. Details of the previous whole valve, note the biseriate striae becoming uniseriate striae composed of 2–4 tiny pores at the end of each stria (arrows). 67. Part of some striae showing the vela. Scale bar =10 μm (Fig. 63), 5 μm (Figs 64–66), 1 μm (Fig. 67).

FIGURES 68–71. Ulnaria gaowangjiensis sp. nov., internal view, SEM. 68. One whole valve, note that the ends are slenderer than in external view (Fig. 63). 69–71. Details of the previous whole valve. Scale bar =10 μm (Fig. 68), 5μm (Figs 69–71).

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).