Afrocymbella cocquytiana Stone & Wilson & Jovanovska 2022, sp. nov.
Creators: name: Stone, Jeffery R.
name: Wilson, Mallory C.
name: Jovanovska, Elena
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Chromista
Ochrophyta
Bacillariophyceae
Cymbellales
Cymbellaceae
Afrocymbella
Afrocymbella cocquytiana

description: Afrocymbella cocquytiana sp. nov. (LM Figs 87–108, SEM Figs 109–115)
Description:— Valve length 35.0–51.5 μm, valve breadth 9.5–12.5 μm. Valves distinctly dorsiventral and heteropolar, semirhomboid-lanceolate (Figs 87–115). Dorsal margin broadly arched, slightly protracted near apices (Figs 87–108). Ventral margin weakly convex, barely tumescent in central area, tapering gently toward apices (Figs 87–108). Footpole narrowing, rounded with APF, headpole distinctly rostrate (Fig. 109). APF externally with round poroids (Fig. 111), internally covered by knobby jointed ridge of silica (Fig. 114). Internally, both poles bear small to indistinguishable pseudosepta (Figs 112, 114, 115). Axial area narrow, curved, slightly ventrally displaced (Figs 87–108). Central area small, broadly elliptical, slightly more arched on dorsal side (Figs 109, 110). A round stigmoid is present on dorsal side of central nodule (Fig. 110), opening internally through elongated slit (Fig. 113). Raphe curved and slightly sinusoidal (Fig. 109). External proximal raphe ends expanded into small pores (Fig. 110). External distal raphe terminal fissures deflected towards the ventral margin (Figs 109, 111). Internal proximal raphe ends covered by nodular or flap-like silica development formed by the primary side of the valve (Fig. 113). Internal distal raphe terminal fissures slightly elevated into small lobed helictoglossa at some distance from valve apices (Figs 112, 114, 115). Striae parallel in the middle, becoming radiate towards the valve apices (Figs 109, 111), 11–12 in 10 μm (central area) and approaching 14 in 10 μm (apices). Central-most striae often more widely and unevenly spaced. Striae continue uninterrupted onto valve mantle (Fig. 109). External areolae slit-like poroids (Figs 109, 110), appearing blocky in LM, 26–30 in 10 μm. Internal areolae ellipsoid without velum (Figs 112, 113).
Type:— REPUBLIC OF ZAMBIA. Upstream from the Kalambo River Falls, at 1220 m elevation, rock scrape, 8°35’47.0” S 31°14’22.3” E, A.Indermaur & F.Ronco, 8 th September 2018 (holotype designated here, circled specimen ANS-GC17198! = Fig. 93, isotypes circled specimens ANS-GC17199!, BM-101980!. Cleaned type materials: ANSGCM 33028.
Registration: https://zoobank.org/NomenclaturalActs/468dba87-d6ff-4bfb-95f7-2f5c20b83e4f
Etymology:— The species name ‘ cocquytiana ’ honors Dr. Christine Cocquyt, who has contributed greatly to the diatom taxonomy of the African Rift lakes.
Distribution:— This species was only observed in abundance from the Kalambo River (Ka), which marks the boundary between Tanzania and Zambia (Fig. 1). We also observed a small population of this species in Isanga Bay (Is) in the southern sub-basin of Lake Tanganyika.
description: Published as part of Stone, Jeffery R., Wilson, Mallory C. & Jovanovska, Elena, 2022, The genus Afrocymbella (Bacillariophyceae) from lakes Malawi and Tanganyika, with description of new fossil and extant species, pp. 21-48 in Phytotaxa 556 (1) on page 35, DOI: 10.11646/phytotaxa.556.1.3, http://zenodo.org/record/6951967