Gomphonema wuyiensis W. Zhang & J. P. Kociolek, 2018

Zhang, Wei, Du, Caili, Kociolek, J. Patrick, Zhao, Ting-Ting & Wang, Li-Qing, 2018, Gomphonema wuyiensis sp. nov., a new freshwater species (Bacillariophyceae) from Wuyi Mountains, China, Phytotaxa 375 (1), pp. 113-120 : 114-115

Gomphonema wuyiensis W. Zhang & J. P. Kociolek sp. nov. ( Figs 1–19 )

LM ( Figs1–6 ): Valves clavate, inflated in the central part, with broadly rounded head pole and narrowly rounded foot pole. Length 42–56 μm, width 10.8–12.9 μm (n= 34). Valve outline asymmetrical to the apical axis. The valve outline on the primary side strongly tapered from the middle part to the footpole, but more moderately on the secondary side. Head pole usually narrower than the valve middle. Axial area narrow, linear to linear-lanceolate, narrowing slightly towards both foot and head pole. Central area rarely indistinguishable, usually asymmetrical, rectangular, formed by one short stria on the secondary side and a slightly shortened stria on the primary side, with a stigma lying close to the latter. Raphe lateral, undulate. External proximal raphe ends weakly dilated. Striae parallel or weakly radiate near the central area, becoming moderately radiate near the apices, 9–11 in 10 μm, up to 12–14 near the apices. Areolae visible in LM, 22–25 in 10 μm.

SEM ( Figs 7–19 ): Striae uniseriate, with “C” shaped openings in the outside, occasionally interrupted by silica so that two pores are formed from a single “C” ( Figs 8, 12 see arrows), extending from the valve face onto the mantle ( Figs 8 , 9,11). External raphe branches undulate ( Fig. 7 ). Proximal raphe ends dilated, drop-like in shape ( Figs 7, 9 ). Distal raphe fissures hooked, curving on the mantle, bi secting the apical porefield at the foot pole ( Figs 8, 10 ). Apical porefield on the footpole composed of several (10–13) rows of small, different sized rounded porelli, structurally differentiated from the areolae. Internal distal raphe endings terminate as small helictoglossae ( Figs 14–15, 18–19 ). Internal proximal endings recurved towards the stigmal openings ( Fig. 14, 15, 17 ). Areolar openings “C” shaped, or round ( Figs. 16, 17, 18 ). Stigmal opening transapically elongated, slit-like, differentiated from the areolae ( Figs. 14, 15, 17 ). No observations on the girdle structure could be made.

Type:— CHINA. Jiangxi Provence: Wuyi Mountains, Xingjiang River, 27° 56′07″ N, 117° 24′54″ E, elevation 255 m, samples collected by W. Zhang (holotype here designated: SHOU!, slide WY-019FS).

Etymology:— Gomphonema wuyiensis is is named after the type locality.

Figures

FIGURES 1–6. Gomphonema wuyiensis, LM, DIC. 1–6. Valve views, showing the size range of the holotype population. Scale bar = 10 μm.

FIGURES 7–13. Gomphonema wuyiensis, SEM. External views. Fig. 7. External view of a whole valve. Figs 8,11. Headpole showing external distal raphe end extending onto the mantle. Fig. 9. Central area show stigma opening differentiated from the areolae. Central area is narrowly rectangular in shape. Fig. 10, 13. Footpole, with bilobed apical pore field restricted to the mantle, comprised of different-sized porelli that are physically removed and differentiated from areolae. Figs 12. Note the C-shaped or round openings of the areolae. Scale bars = 10 μm (Fig. 7), 2 μm (Figs 8, 9), 1 μm (Figs 10–12), 0.5 μm (Fig. 13)

FIGURES 14–19. Gomphonema wuyiensis, SEM. Internal views. Fig. 14–15. Internal view of a whole valve, showing central nodule. Figs 16, 18. Headpole showing helictoglossa at the raphe terminus. Fig. 17. Central area with internally-projecting central nodule bearing slit-like stigmal opening and recurved proximal raphe ends. Fig 19. Footpole showing a small helictoglossa at the raphe terminus. Scale bars = 10 μm (Figs 14–15), 2 μm (Figs 16–19).