Gomphoneis distorta Q. You & Kociolek, 2013

You, Qingmin, Kociolek, John Patrick & Wang, Quanxi, 2013, New Gomphoneis Cleve (Bacillariophyceae: Gomphonemataceae) species from Xinjiang Province, China, Phytotaxa 103 (1), pp. 1-24 : 19-20

Gomphoneis distorta Q. You & Kociolek , sp. nov. ( Figs 97 –108; figure 98 is holotype)

Type:— CHINA. Little Kalakule Lake , Kunlun Mountains ( SHTU, slide XJ-071015! holotype illustrated in figure 98) .

In LM, valves linear-clavate straight or with only a slight tumid swelling at the center, headpole narrowly rounded and footpole rounded. Length 30.0– 45.2 µm, breadth 5.5–7.5 µm. Axial area narrow, expanded to form a small, round to elliptical, to sometimes nearly rectangular central area, stigmoids wanting. Raphe straight, lateral, with external proximal ends dilated slightly and external distal raphe ends extending straight to the terminus. Internal distal raphe ends are indistinct. Costate striae 10–14/ 10 µm, arched and strongly radiate around the center, with 1–2 shortened striae on either side of the central area. Striae towards the headpole become parallel and nearly convergent towards the terminus. Towards the footpole striae are radiate to parallel. Septa and pseudosepta indistinct. Apical pore fields bisected, distinct at the footpole.

In the SEM, the exterior of the valve is dominated with striae composed of two rows of areolae ( Figs 103–

105). The headpole has striae that extend onto the mantle, and the distal raphe end is deflected slightly before reaching the apex and extending onto the mantle ( Fig. 103 ). The central area has dilated proximal raphe ends and striae that are biseriate near the margins but taper to uniseriate striae towards the axial area and central area ( Fig. 104 ). The apical pore fields have porelli in distinct rows and extend all over the mantle ( Fig. 105 ).

Internally, the valve interior has prominent helictoglossae and pseudosepta at the poles (Figs 102, 106, 108). The central part of the valve has a slightly raised central nodule, where deflected proximal raphe ends occur. Striae become uniseriate near the axial area, and in this region strong thickenings are evident (Fig. 107).

Etymology:— The species is named for its slightly distorted valve outline.

Distribution and ecology:— Little Kalakule Lake, Kunlun Mountains, Xinjiang, China, altitude 3300m, pH 9.0, collected in the wetland near the lake (summarized in Table 1).

Observations:— This species is differentiated from G. stoermeri in being more linear in outline, without the distinct tumid middle section of the valves.

Figures

PLATE 16, FIGURES 97–101. Gomphoneis distorta, LM. Valve views showing size diminution series. Figure 98 is the holotype. Scale bars = 10 µm for all figures.

PLATE 17, FIGURES 102–108. G. distorta, SEM. Figs 103–105, external views. Figs 103, 105. Apices showing doubly-punctate striae and, at the footpole, apical pore field with porelli similar to the areolae. Fig. 104. Central area with dilated proximal raphe ends and striae tapering from biseriate to uniseriate. Figs 102, 106–108, internal view. Fig. 102. Entire valve view. Note prominent helictoglossae and central nodule. Fig. 106. Headpole with helictoglossa slightly offset from main axis of raphe. Fig. 107. Raised central nodule with proximal raphe ends deflected in the same direction. Internal thickenings are evident in the striae near the axial area. Fig. 108. Footpole, with prominent helictoglossa, small pseudoseptum and thin interstriae dividing the porelli.