Gomphoneis stoermeri 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 : 14-17

Gomphoneis stoermeri Q. You & Kociolek , sp. nov. ( Figs 67–83 ; figure 68 is holotype)

Type:— CHINA. Little Kalakule Lake , Kunlun Mountains ( SHTU, slide XJ-071015! holotype illustrated in figure 68) .

In LM, valves linear-clavate with a prominent tumid swelling at the center, headpole narrowly rounded and footpole rounded. Length 36.0– 54.7 µm, breadth 5.9–7.6 µm. Axial area narrow, expanded to form a small, round to elliptical central area, stigmoids wanting. Raphe straight, filiform, with external proximal ends dilated slightly and external distal raphe ends extending straight to the terminus. Internal distal raphe ends are indistinct. Costate striae 10–13/ 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 valve exterior has striae composed of two rows of small, round puncta (Figs 78–80). At the headpole, the striae continue from the valve face to the mantle (Fig. 78), while at the footpole the porelli of the apical pore field are organized similar to the striae, but more condensed (Fig. 80). At the center of the valve striae are doubly-punctate at the margin, but taper and near the center of the valve are uniseriate (Fig. 79). The raphe is straight, with proximal ends dilated and tear-drop shaped (Fig. 79), while at the poles the distal ends are deflected slightly and extend onto the mantle (Figs 78, 80).

Internally, the proximal raphe ends are short and deflected in the same direction near the ends of the raised central nodule (Figs 77, 82). Around the central area the uniseriate portions of the striae are seen to have thickenings ( Fig. 82 ). The apices have distinct helictoglossae and pseudosepta ( Figs 81, 83 ). Internal ribs separate apical pore field porelli into rows ( Fig. 83 ).

Etymology:— Named in honor of Dr. Eugene F. Stoermer, who was interested in diatom research in China and published extensively on the genus Gomphoneis .

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).

Figures

PLATE 12, FIGURES 67–76. Gomphoneis stoermeri, LM. Valve views showing size diminution series. Figure 68 is the holotype. Scale bar = 10 µm for all figures.

PLATE 13, FIGURES 77–83. G. stoermeri. SEM. Figs 78–80, external views. Fig. 78. Headpole, showing slight bend in the raphe branch, which does not extend onto the mantle. Striae composed of two rows of areolae extend well onto the mantle. Fig. 79. Central area with striae tapering from double to single rows and proximal raphe ends are dilated. Fig. 80. Apical pore field has porelli aligned in double rows at the footpole. The raphe bends slightly before bisecting the pore field. Figs 77, 81–83, internal views. Fig. 77. Entire valve view, with central nodule, helictoglossae and pseudoseptae prominent. The expanded central area is distinct. Figs 81, 83. Headpole and footpole, respectively., with helictoglossae prominent and pseudosepta present. Fig. 82. Central area with raised central nodule bearing proximal raphe ends recurved. Striae taper from doubly punctate to uniseriate. Prominent thickenings oriented perpendicular to the interstriae occur at the point when the striae have single rows of areolae.