Ulnaria chengduoensis Bing Liu, 2023
Liu, Bing, 2023, The diatom genus Ulnaria (Bacillariophyta) in China, PhytoKeys 228, pp. 1-118 : 1
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publication ID |
https://dx.doi.org/10.3897/phytokeys.228.101080 |
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persistent identifier |
https://treatment.plazi.org/id/82643DCA-64CC-50BB-A3EA-F40492A5647F |
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treatment provided by |
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scientific name |
Ulnaria chengduoensis Bing Liu |
| status |
sp. nov. |
Ulnaria chengduoensis Bing Liu sp. nov.
Figs 54 View Figure 54 , 55 View Figure 55 , 56 View Figure 56
Holotype.
Slide JIUDIA202309, specimen circled on slide, illustrated as Fig. 54A View Figure 54 .
Registration.
PhycoBank http://phycobank.org/103815.
Type locality.
China. Qinghai province: Chengduo County, Baima River, at a sampling location (33°22'21"N, 97°0'18"E, 3690 m a.s.l.), collected by Bing Liu, July 22, 2019.
Description.
LM (Fig. 54 View Figure 54 ). Valves linear with rostrate apices (Fig. 54A-P View Figure 54 , see also Figs 55E View Figure 55 , 56A-C View Figure 56 ). Valve dimensions (n = 51): length 42-66 μm, width 6-8 μm at centre. Sternum distinct, extending length of valve. Central area not clearly visible due to presence of ghost striae (Fig. 54A-G, I-K, M View Figure 54 ) or completely lacking (Fig. 54H, L, N-P View Figure 54 ). Striae parallel, radiate only approaching each pole, 12-15 in 10 μm. Across sternum some striae opposite one another, others alternate.
SEM (Figs 55 View Figure 55 , 56 View Figure 56 ). Valve characterized by a series of relatively wide virgae, interconnected with vimines (Fig. 55B-D View Figure 55 ). Striae uniseriate, areolae often apically elongated (Fig. 56E View Figure 56 ). Central area variable: a hyaline area circumscribed by both short marginal striae and isolated areolae (Figs 55B View Figure 55 , 56A, B View Figure 56 ), or completely absent (Figs 55F View Figure 55 , 56E View Figure 56 ). One rimoportula located at each pole, externally expressed as a simple hole (Fig. 55C, D View Figure 55 ), internally bilabiate, situated close to sternum (Fig. 56D, F View Figure 56 ). Ocellulimbus composed of ca. 12 pervalvar and 9 transverse rows of porelli (Fig. 56F View Figure 56 ).
Etymology.
Named after Chengduo County, where this species was found.
Ecology and distribution.
Epilithic in a plateau river. The following environmental parameters were measured in the field: Conductivity was 422.7 ± 1.3 μS ∙cm-1, pH was 8.2 ± 0.1 and water temperature was 12.2 ± 0.5 °C. So far, its distribution is known only from the type locality.
Discussion.
Ulnaria chengduoensis is characterized by its linear valve outline, variable central area, narrow rostrate valve apices. It differs from U. ramerii and U. verhaegeniana by its variable central area, i.e., it may completely lack a central area whereas U. ramerii always possesses an ellipsoid to rectangular central area (see Morales et al. 2007, p. 73, figs 87-94, as Synedra ulna var. ramesi ) and U. verhaegeniana always has a large, apically elongated, rectangular central area (see Van de Vijver et al. 2017, p. 223, figs 1-13).
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