Cymbopleura deqinensis Y.-L. Li, 2022

Meng, Wen-Wen, Guo, Ji-Shu, Zhang, Yu, Kociolek, John Patrick & Li, Yan-Ling, 2022, Cymbopleura deqinensis sp. nov. (Cymbellaceae; Bacillariophyceae), a new species from Yunnan Province, China, Phytotaxa 550 (3), pp. 233-242 : 234-235

Cymbopleura deqinensis Y.-L. Li sp. nov. ( Figs 1–33 )

Description:— LM ( Figs 1–20 ): Valves linear-lanceolate, commonly asymmetrical about the apical axis, dorsal and ventral margins similarly arched or occasionally parallel, apices rostrate to subcapitate bent in opposite directions. Length 27–31 um, width 6.0–7.5 um, length/width ratio varying between 3.8–4.7, median 4.3 (n=30). Raphe slightly lateral, narrowing towards the distal and proximal ends. External central raphe ends deflected gently towards the ventral side and tipped with slightly inflated pores. External terminal raphe fissures hooked towards dorsal margin. Axial area very narrow, linear or slightly broader towards the central area, approximately in the median line of the valve. Central area rectangular to elliptical, almost asymmetrical and then more well-developed dorsally or ventrally, occupying 1/3–1/2 of the valve width, with 2–3 markedly shortened central dorsal striae, and 3–4 slightly shortened central ventral striae, occasionally lacking or not well expressed. Striae radiate more strongly towards the apices, indistinctly punctate-lineate, more widely spaced at the valve centre dorsally, density 14–18 in 10 µm in the middle portion, up to 20–22 in 10 µm towards the ends. Individual areolae not visible.

SEM: Valve exterior ( Figs 21–28 ): Raphe undulate with proximal raphe ends dilated and slightly ventrally deflected near the valve centre ( Figs 21, 22, 27, 28 ), terminal fissures hooked, deflected towards the dorsal side, terminating between shortened striae extending around the apices ( Figs 21–26 ). Striae uniseriate, slightly radiate throughout ( Figs 21–28 ). Areolae mostly round to elliptical, partly T-shaped, V-shaped or irregularly shaped along the axial area and central area, 30–40 in 10 μm ( Figs 21–28 ), with 8–10 areolae larger than the rest near the central area in size ( Figs 27–28 ). No stigmata and apical pore fields present ( Figs 21–28 ).

Valve interior ( Figs 29–33 ): Striae formed by uniseriate, round areolae delimited by slightly oblique orientated vimines ( Figs 29–33 ). Internal raphe slit continuous, without intermissio ( Figs 29, 30, 33 ). Terminal raphe ends offset, bent slightly towards the dorsal margin, and terminating in small, knob-like helictoglossae adjacent to the shortened striae ( Figs 29–32 ). Stigmata absent ( Figs 29, 30, 33 ).

Type:— CHINA. Yunnan Province: Deqindong-2 Lake, Deqin country, sediment, 28.5263°N, 98.99146°E, elevation 4901 m asl., Prof. Yan-Ling Li, Sept. 1 2016. (Holotype DQD 2016090101 in Coll. Yan-Ling Li! Yunnan University, Kunming, China = Fig. 1 ; Isotype YUNGL20210824 , Harbin Normal University, Harbin, China) .

Etymology:— deqinensis , refers to the type locality from which the new species was obtained.

Ecology:— Cymbopleura deqinensis is known only from the surface sediments of an unnamed lake occurring at about 4901 m asl. At the type locality, C. deqinensis was uncommon (<1% abundance); the related species in decreasing order of abundance were Staurosira construens f. venter (Ehrenberg) Bukhtiyarova (1995: 418) , Diatoma vulgaris Bory (1824: 461) , C. naviculiformis K. Krammer (2003: 56) , Denticula elegans Kützing (1844: 44) , Denticula tenuis Kützing (1844: 43) , S. construens f. construens Ehrenberg (1843: 424) .

Figures

FIGURES 1–20. Cymbopleura deqinensis sp. nov., LM, DIC. Valve views, showing size range and variability of the holotype population. Scale bar = 10 μm.

FIGURES 21–28. Cymbopleura deqinensis sp. nov., SEM, external views. 21, 22. External view of an entire valve. 23, 26. Detail of valve apices showing, striae with rounded areolae and the distal raphe fissures. 27, 28. External view of valve centre showing the proximal raphe endings and larger areolae surrounding the central area, the black arrows in the figure indicate partly T-shaped, V-shaped or irregularlyshaped areolae, the white arrows in the figure indicate several larger areolae near the central area. Scale bar = 2 μm (Fig. 21), 1 μm (Figs 22–28).

FIGURES 29–33. Cymbopleura deqinensis sp. nov., SEM, internal views. 29, 30. Internal view of entire valve. 31, 32. Detail of valve apices with prominent helictoglossa deflected to the dorsal side. 33. Detail of the valve central area showing the intermissio is lacking. Scale bar = 2 μm (Figs 29–30), 1 μm (Figs 31–33).