Cocconeis scutellum var. parva (Grunow) Cleve (1895: 170) Cocconeis scutellum f. parva Grunow Cocconeis scutellum var. parva (Bacillariophyceae) re-examination and typification Riaux-Gobin, Catherine Witkowski, Andrzej Igersheim, Anton Phytotaxa 2018 2018-03-06 343 1 20 34 (Grunow) Cleve (1895: 170) Cleve 170 1895 Grunow [136,826,1844,1871] Bacillariophyceae Cocconeidaceae Cocconeis GBIF Chromista Achnanthales 3 23 Bacillariophyta variety scutellum parva   Basionym:—  Cocconeis scutellumf. parvaGrunowin Van Heurck (1880–1885: pl. 29, figs 8–9, reproduced here as Figs 4–5).   Description in Cleve (1895: 170):— ‘var. parvaGrunow (1881). L. 0.018 to 0.02; B. 0.01 to 0.017 mm. Upper V. with 11 rows of puncta in 0.01 mm. Marginal puncta elongated.Axial area narrow. V.H. Syn. pl. XXIX f. 8, 9.  C. consociataand  C. aggregataKützingaccording to Grunow  C. transversalisGregory M. J. IIIp. 39 Pl. IV f. 7; 1854?’ [1857] ‘  C. scut. var. minorA.S. Atl. CXC.22.’ (pl. 190, fig. 22). ‘Marine: Baltic! East Cape! Adriatic (Atl.).’    Lectotype(designated here):— Slideno  1035 inGrunow’sslide collection ( Fig. 8, specimens illustrated in Figs 9–16) ( McNeill et al.2012, art. 9.7). Nothingelse has been traced that could be considered as original material studied by Albert Grunow. For both W and BRcollections, no raw material (from which the slide was made) was found, thus SEM cannot be conducted on this material.  LM observation of the   lectotype( Figs 9–16, Table 2):—The slide number 1035 ( Fig. 8), contains an abundance of small Cocconeidaceae, including numerous small individuals that match the drawings by Albert Grunow ( Figs 4–5). Valves oblong-elliptical with round apices ( Figs 9–16). Frustules 13–24 μm long, 8.0–14.5 μm wide, L/W 1.6 ± 0.1 (n = 32, Table 2). SV striae radiate, equidistant ( 11–14 in10 μm) composed of round areolae arranged into apical rows ( Figs 13–16), with marginal groups of three to four coalescent areolae ( Figs 14–16). SV sternum narrow and straight. RVstriae radiate, equidistant ( 12–14 in10 μm), composed of round areolae ( Figs 9–12). Presence of a marginal well-marked RVrim; valvocopula with irregularly positioned fimbriae ( Fig. 10). Raphe straight, proximal raphe endings well spaced ( Fig. 9).   Remarks on the lectotype:—Grunow’s illustration in Van Heurck (1880–1885: pl. 29, fig. 9 reproduced in Fig. 5), show similar stria densities for both valves ( op. cit.: fig. 8, reproduced in Fig. 4). In the drawings by Grunow, the RV marginal scalar short bars (from the edge of the valve to the rim, Fig. 5) are not oblong areolae but instead, the fimbriae of the RVVC. From Fig. 4( op. cit.), the marginal SV areolae are not unique transapically (or apically) oblong areola, but are built up with several coalescent small areolae. Figs 14–15match the original drawings.  Cocconeis scutellumvar. parvaSV, except for its small size and slightly denser striation than in the nominate variety, is very close to that of  Cocconeis scutellum(e.g., Figs 2–3). See ‘  Cocconeis scutellumvar. parvahistory and ambiguities’ in Discussion.   Epitype(here designated):population from Rodrigues Island, sample ROD1  LM observation of the epitype( Figs 17–25, Table 2):—Valves small, RV and SV stria density similar ( Table 2), SV with more or less regular axial rows of areolae ( Figs 17–19), SVVC (sternum valve valvocopula) closed, with short digit fimbriae ( Fig. 23). Numerous teratologic forms observed ( Figs 24–25).  SEM observation of the epitype( Figs 26–32, Table 2):—Valves small ( Table 2), oblong elliptical, with round to sub-quadrangular SV areolae, SV striae uniseriate with marginal cluster of small areolae ( Fig. 26). SV and RV areola hymenes flat, with radially arranged marginal slits and scattered dots in mid-part ( Fig. 30). RV with continuous submarginal hyaline area in external view ( Fig. 29arrowhead) and internal continuous rim with bumps ( Fig. 28arrow). RVVC fimbriae on each virga, absent on rim, and bumps ( Fig. 32). Regularly spaced fimbriae, oblong papillae with several transverse furrows on abvalvar side ( Fig. 32arrowhead). SV and RV areola hymenes ( Figs 30–31) with short radial slits.  Remarks on the epitype:—The morphometrics and morphology of the specimens from some other tropical prospected sites ( Table 2, not illustrated) were very similar to those in Rodrigues (except for the RVVC papillae that are often longer). These tropical specimens were assigned to  C. scutellum cf. var. parva. It cannot be dismissed that these tropical taxa may all pertain to a continuumfrom the nominate variety forthe larger ones, to  C. scutellumvar. parvafor the smaller ones. BR Slide Nothing 4 24 1 lectotype RV 4 24 1 lectotype Raphe straight 4 24 1 lectotype