Ulnaria sangzhi-biseriata Bing Liu, 2023

Liu, Bing, 2023, The diatom genus Ulnaria (Bacillariophyta) in China, PhytoKeys 228, pp. 1-118 : 1

publication ID	https://dx.doi.org/10.3897/phytokeys.228.101080
persistent identifier	https://treatment.plazi.org/id/9F2CEEEE-746C-5AAD-8A24-70264C149BBA
treatment provided by	PhytoKeys by Pensoft
scientific name	Ulnaria sangzhi-biseriata Bing Liu
status	sp. nov.

Treatment

Ulnaria sangzhi-biseriata Bing Liu sp. nov.

Figs 30 View Figure 30 , 31 View Figure 31 , 32 View Figure 32 , 33 View Figure 33 , 34 View Figure 34

Holotype.

Slide JIUDIA202304, specimen circled on slide, illustrated as Fig. 30C View Figure 30 .

Registration.

PhycoBank http://phycobank.org/103810.

Type locality.

China. Hunan province: Sangzhi County, Wudaoshui Town, Jinlong power station, Li River (29°43′7.1″N, 109°54′50.9″E, 398 m a.s.l.), collected by Bing Liu, September 30, 2015.

Description.

LM (Fig. 30 View Figure 30 ). Valves linear-lanceolate with central margins sometimes very slightly constricted and capitate to sub-capitate apices (Fig. 30A-I View Figure 30 , see also Figs 32A, E View Figure 32 , 33A View Figure 33 , 34A, E View Figure 34 ). Valve dimensions (n = 22): length 49-91 μm, width 6.5-8.2 μm at centre. Sternum discernible, extending length of valve. Central area rectangular or square. Ghost striae present in central area (e.g., Fig. 30B-D View Figure 30 ). Striae parallel, radiate only at poles, and mostly opposite each other across sternum. Stria density 10-12 (often 11) in 10 μm.

SEM (Figs 31 View Figure 31 - 34 View Figure 34 ). Frustule rectangular in girdle view (Fig. 31A View Figure 31 ). Epivalve associated with valvocopula and three copulae (Fig. 31C, D View Figure 31 , labelled B1-B4, B1 = valvocopula). Valvocopula is a closed hoop, attached to the mantle interior, surrounding the valve internal margin (Fig. 32A, E View Figure 32 ). The valvocopula has a mostly continuous row of poroids dividing pars interior from pars exterior, located at the midline (Fig. 26B-D View Figure 26 ). On its advalvar edge there is a row of serrated projections, each corresponding internally to a virga (Figs 31B View Figure 31 , 32B-D, F View Figure 32 , two arrowheads respectively), ornamentation is lacking at either pole (Fig. 32C, D, F View Figure 32 ). Valve face and mantle intersect almost at right angle (Fig. 33A-F View Figure 33 ). Central hyaline area rectangular or square (Figs 33B, E View Figure 33 , 34B, F View Figure 34 ). Valve characterized by a series of relatively wide virgae, interconnected with thin viminules and closing plates affixed with a few struts to the areolar wall (Figs 32A-F View Figure 32 , 33B-F View Figure 33 , closing plate see Fig. 33F View Figure 33 , two wavy arrows). Valve has two types of mixed striae: most striae of the valve are composed of a biseriate main part and a uniseriate minor part near the sternum (usually 1 or 2 areolae, Figs 33B-F View Figure 33 , 34B-D, F View Figure 34 ), and the rest are composed of a biseriate part, a triseriate part, and a uniseriate part near sternum (usually 1 or 2 areolae) (Fig. 34C, D View Figure 34 , two arrows respectively). Ocellulimbus composed of ca. 18 pervalvar and 7 transverse rows of porelli. A few serrated apical outgrowths protruding over each ocellulimbus (Fig. 33C, D, F View Figure 33 , two arrows respectively). Striae continue onto mantle, absent in the centre (Fig. 31B View Figure 31 ). One rimoportula at each pole (Figs 33C, D, F View Figure 33 , 34C, D View Figure 34 ), externally expressed as a simple hole in different shapes (Fig. 33C, D, F View Figure 33 ), internally bilabiate, situated close to sternum (Fig. 34C, D View Figure 34 ).

Etymology.

The epithet sangzhi-biseriata is a combination of Sangzi and the term biseriate to reflect its type locality (Sangzi) and its mostly biseriate striae.

Ecology and distribution.

The sampling site is near Wudaoshui Town, and some human activities may have affected the environment and hence the diatoms. The diatom samples were scraped off of the stone surfaces. The following environmental parameters were measured in the field: Conductivity was 219.3 ± 1.2 μS ∙cm-1, pH was 8.5 ± 0.2 and water temperature was 17.9 ± 0.3 °C. To sum up, U. sangzhi-biseriata lives on the stone surfaces of a mountainous river flowing away from the Town. So far, its distribution is known only from the type locality.

Discussion.

Ulnaria sangzhi-biseriata is characterized by its linear-lanceolate valve outline, mostly biseriate striae, rectangular or square central area, and capitate to sub-capitate apices. It is similar to U. goulardii which has a more constricted valve central margin. Moreover, the former has capitate to sub-capitate apices whereas U. goulardii has rostrate apices (see Williams 1986, p. 141, figs 27-36, as Synedra goulardii ).