Entomoneis qinghainensis Bing Liu & D.M. Williams, 2022

Long, Ji-Yan, Williams, David M., Liu, Bing, Mo, Wen-Hui & Quan, Si-Jin, 2022, Ultrastructure of three Species of Entomoneis (Bacillariophyta) from Lake Qinghai of China, with reference to the external areola occlusions, PhytoKeys 189, pp. 29-50 : 29

Entomoneis qinghainensis Bing Liu & D.M. Williams sp. nov.

Figs 8 , 9 , 10 , 14

Holotype.

Slide BM 81942, the holotype specimen circled on the slide, illustrated here as Fig. 8A ; isotype, slide JIU202102, illustrated here as Fig. 8B .

Type locality.

China. Qinghai Province, Lake Qinghai, a sampling point near the lakeshore, 36°50'34" N, 99°42'39" E, 3210 m a.s.l., collected by Bing Liu, 19 July 2019.

Description.

LM (Fig. 8 ). Frustules panduriform in girdle view (Fig. 8A and B ). Frustule dimensions (n = 19): length 67.1-116.5 μm, width 21.6-37.5 μm at middle constricted part, 46.6-62.5 μm at widest part. Keel very high. Hymen strip region distinct, like a U-shaped neck pillow, located at the middle of each lobe of valve (indicated in Fig. 8C ). Junction line sinuous with a distinct bulge into the hymen strip region (Fig. 8 , see also Fig. 9A ). Striae visible under LM, 18-23 in 10 μm. Girdle bands numerous.

SEM, girdle view (Figs 9 and 10 ). Frustule panduriform, composed of epivalve, girdle bands and hypovalve (Fig. 9A ). Junction line confirmed same as LM observation (Fig. 9A , dotted line). Costae mostly running from raphe canal to mantle, but sometimes two costae merging into one (Fig. 9B , arrow). Hymen strip region composed of costae and hymen strips (Fig. 9A and C , two arrows, respectively; Fig. 10B and C , two double-headed arrows, respectively). This type of hymen strip belongs to Type One hymen strip, which are a siliceous membrane strip perforated by irregularly distributed round pores (Fig. 14C and D ). Mantle thickened (Fig. 10B , two arrows). Six girdle bands associated with epivalve (Fig. 10E , labeled B1 to B6). Structure of each girdle bands similar, composed of pars exterior, pars media, and pars interior. The poroids of each girdle band elongate (Fig. 10F ).

Etymology.

Named after Lake Qinghai, where the species was found.

Ecology and distribution.

Entomoneis qinghainensis was commonly found on the stone surfaces in Lake Qinghai with E. sinensis . According to above data and because Lake Qinghai is a brackish water lake, E. qinghainensis should be a brackish water diatom species. So far, E. qinghainensis is only found in the type locality and is not a dominant species.

Figures

Figure 8. A-C Entomoneis qinghainensis sp. nov., girdle view, LM A, B two whole frustules, note the distinctive hymen strip region (labelled in Fig. C) C epivalve with associated girdle bands, note the hymen strip region and junction line A micrograph of holotype specimen B micrograph of isotype specimen. Scale bar: 20 μm.

Figure 9. A-C Entomoneis qinghainensis sp. nov., frustule view, SEM A one complete frustule, note the undulate junction line (indicated by dotted line) and the hymen strip region B detail from Fig. A note the striae composed of many single areolae near the sternum and two costae merging into one (arrow) C detail from Fig. A note hymen strips (two arrows). Scale bars: 10 μm (A); 2 μm (B, C).

Figure 10. A-F Entomoneis qinghainensis sp. nov., girdle view, SEM A one valve with numerous girdle bands B, C two apices from Fig. A note the hymen strip regions (two double-headed arrows, respectively) D central part from Fig. A note thickened mantle E, F two girdle details from Fig. A note at least six girdle bands (labelled B 1 to B 6) associated with the epivalve. Scale bars: 10 μm (A); 5 μm (B-F).

Figure 14. A-F Details of hymen and hymen strip in Entomoneis, SEM A, B details of hymen strip of Type Two from E. sinensis sp. nov., note the two rows of linear pores (Fig. A, two arrows) on either side of the two intermittent rows of rounded pores (Fig. A, wavy arrow) C, D details of hymen strip of Type One from E. qinghainensis sp. nov., note the hymen is finely perforated over both the areolae (Fig. D arrow) and the hymen strips (Fig. D, double-headed arrow) E detail of hymen strip of Type One from E. paludosa, note the hymen is finely perforated over both the areolae and the hymen strips (double-headed arrow) F detail of hymenes from E. triundulata, note the hymenes of the areolae in the girdle bands (two arrows). Scale bars: 600 nm (A-F).