Gomphonema subinsigniforme L. Ge, Y. Liu & J. P. Kociolek, 2014

Ge, Lei, Liu, Yan, Kociolek, J. Patrick & Fan, Yawen, 2014, A new species of Gomphonema (Bacillariophyta) from Xingkai Lake, China, Phytotaxa 175 (5), pp. 249-255 : 251-253

Gomphonema subinsigniforme L. Ge, Y. Liu & J. P. Kociolek sp. nov. ( Figures 1–26 ; holotype illustrated in Fig. 10 )

Type:— CHINA. Heilongjiang Province: Xingkai Lake, from lakeside, marsh near the road, epiphyte on moss, collected 13 th June 2011 ( HANU 11 xkR14, holotype!, Fig. 10 = holotype specimen; Museum of Natural History, University of Colorado , Boulder ( COLO), 560033, isotype!) .

Valves lanceolate–clavate, tumid at the centre, with headpole acute, footpole, narrowly rounded. Length 31.4–64.4μm, breadth 7.1–8.1μm. Raphe slightly undulate, lateral, with external proximal raphe ends dilated and internal proximal raphe ends recurved. External distal raphe ends deflected onto mantle.Axial area narrow, central area indistinct, formed by central striae being slightly more distant from other, shorter, with round external stigmal opening positioned at the end of a central stria. Striae radiate at center, slightly radiate at headpole and footpole, Striae punctate, 9–10 in 10μm.

Observations:— In the SEM, externally the slightly undulate valves have radiate striae comprised of areolae. The axial area is linear, straight and the central area is round or elliptical in shape and possesses the round stigmal opening ( Fig 15 ). At the headpole, the raphe is first deflected to one side, then extending onto the valve mantle on the other side ( Fig. 16 ). At the footpole, the raphe is deflected to one direction, and curves and bisects the bi-lobed apical pore field ( Fig. 18 ). The apical pore field is comprised of a few rows of rounded porelli of differing shapes and sizes. It is physically separate and morphological distinct from the striae ( Fig. 18 ) and positioned almost entirely on the valve mantle ( Fig. 18 ). In the central portion of the valve is the small, oval-shaped proximal raphe ends that are dilated slightly ( Fig. 17 ). Opening of the stigma is visible, situated close to the end of a central stria ( Fig. 19 ). Areolae are Cshaped or Ɛ-shaped ( Fig. 20 ).

Internally the central nodule is small, oblong in shape, and bears proximal raphe ends that are hooked ( Fig. 22 ). An ovoid to slit-like stigmal opening is present on one side the central nodule ( Figs 21, 22 ). There is a helictoglossa at the footpole that is barely offset from the axial area ( Fig. 23 ). A small pseudoseptum at the headpole is present ( Fig. 24 ). Smaller struts help to distinguish the apical fields, which are covered internally by the pseudoseptum ( Fig. 23 ). The areolae are situated in deep grooves, each areolae is a “C” shape or “Ɛ” shape ( Figs 25, 26 ).

Figures

FIGURES 1–14. Gomphonema subinsigniforme sp. nov. LM of valve view showing the range of variability. Figure 10 is of the Holotype. Scale bar=10μm.

FIGURES 15–20. Gomphonema subinsigniforme sp. nov. SEM, external views. Fig. 15. External view of entire valve. Fig. 16. Detail of headpole with deflected distal raphe fissure. Fig. 17. Central area showing dilated proximal raphe end (arrow) and rounded stigma opening. Fig. 18. Detail of apical pore field. Arrow indicates elongated porelli and variable size and shape. Fig. 19. Detail of stigmal opening (arrow). Fig. 20. Detail of areolar structure. Scale bars = 5μm (Fig. 15), 2.5μm (Fig. 17), 2μm (Fig. 16), 1μm (Fig. 19), 0.5μm (Figs 18, 20).

FIGURES 21–26. Gomphonema subinsigniforme sp. nov. SEM, internal views. Fig. 21. Interior view of entire valve. Fig. 22. Detail of central nodule, showing curvature of proximal raphe end (black arrow) and slit-like stigmal opening (white arrow). Fig. 23. Detail of helictoglossa, offset from raphe branch (white arrow) and pseudoseptum at footpole (black arrow). Fig. 24. Detail of helictoglossa (black arrow) and pseudoseptum at headpole (white arrow). Figs 25, 26. Detail of areolae within deep troughs. Scale bars =5μm (Fig. 21), 2μm (Figs 22–24), 0.5μm (Figs 25–26).