Gomphoneis pseudosubtiloides 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 : 5

Gomphoneis pseudosubtiloides Q. You & Kociolek , sp. nov. ( Figs 15 –25; figure 16 is holotype)

Type:— CHINA. Little Kalakule Lake , Kunlun Mountains ( SHTU, slide XJ-071015! holotype illustrated in figure 16) .

In LM, valves lanceolate-clavate with broadly capitate headpole and broadly rounded footpole. Length 45.4– 51.0 µm, breadth 8.1–8.6 µm. Axial area narrow, straight, expanded at the center to form a broad, rectangular central area bordering at the margins by 2–3 approximately equally-shortened striae. Stigmoids in the central area wanting. Raphe lateral, weakly undulate, with external proximal ends dilated, rounded, extending into the central area, and external distal raphe ends extended straight to the valve terminus at both poles. Internal proximal raphe ends small, deflected in the same direction, while internal distal raphe ends (“terminal nodules”) are distinct, positioned well before the valve terminus. Costate striae number 9–12/ 10 µm, are arched about the center of the valve and strongly radiate, becoming parallel towards the poles. Septa and pseudosepta prominent. Apical pore fields relatively large, distinct.

In the SEM, the exterior around the central area has doubly-punctate striae tapering to finer striae with single rows of puncta. Proximal raphe ends are dilated and circular (Fig. 21). At the headpole, the raphe does not bend and proceeds onto the valve mantle. The wide striae have round puncta arranged in two rows (Fig. 20). At the footpole, the porelli appear to be arranged in double rows, similar in appearance to the puncta, but condensed as to be a finer density. The distal raphe end extends onto the valve mantle (Fig. 22).

Internally, the raphe lies atop a ridge ( Fig. 19 ). The central area is undifferentiated, and the proximal raphe ends are recurved along the raised central nodule. The striae are seen to be composed of double rows near the margin, single rows near the central area (Fig. 24). Narrow pseudosepta are present at the poles, and the helictoglossae are prominent (Figs 23, 25). Striae are composed of double rows of puncta along their entire length. At the footpole, the narrow interstriae are evident separating the rows of porelli (Fig. 25).

Etymology:— The species name is based on its resemblance to G. subtiloides .

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 3, FIGURES 15–18. Gomphoneis pseudosubtiloides, LM. Valve views showing size diminution series. Figure 16 is the holotype. Scale bar = 10 µm for all figures.

PLATE 4, FIGURES 19–25. G. pseudosubtiloides. SEM. Figs 20–22, external views. Fig. 20. Headpole, showing striae convergent near the apex and distal raphe end extending onto mantle. Fig. 21. Central area with proximal raphe ends dilated and radiate striae around the center terminating in single rows of areolae. Fig. 22. Bilobed apical pore field has porelli aligned in two rows, and they resemble the areolae. Distal raphe end bisects the pore field. Figs 19, 23–25, internal views. Fig 19. Entire valve view show prominent axial area and expanded central area. Fig. 23. Headople with pseudoseptum and helictoglossa evident. Fig. 24. Central area with raised central nodule, recurved proximal raphe ends and striae terminating as single rows of areolae. Fig. 25. Footpole with prominent helictoglossa and distinct divisions between rows of porelli of the apical pore field.