Cocconeis molesta Kütz. ( Kützing 1844 )

Riaux-Gobin, Catherine, Compère, Pierre, Jordan, Richard W., Coste, Michel & Yesilyurt, Jovita C., 2016, Cocconeis molesta Kütz., C. diaphana W. Sm. and C. dirupta W. Greg. (Bacillariophyta): type material, ambiguities and possible synonymies, European Journal of Taxonomy 204, pp. 1-18 : 6-8

publication ID

https://doi.org/ 10.5852/ejt.2016.204

DOI

https://doi.org/10.5281/zenodo.3853036

persistent identifier

https://treatment.plazi.org/id/003BB414-F621-3E61-576A-0B5EFBCDC075

treatment provided by

Valdenar

scientific name

Cocconeis molesta Kütz. ( Kützing 1844 )
status

 

Cocconeis molesta Kütz. ( Kützing 1844)

Figs 1 View Figs 1–8 , 15–20 View Figs 15–20 , Table 1 View Table 1

Cocconeis molesta var. crucifera Grunow ex Cleve (1895: 174) . Type: pl. 30, fig. 23 in Van Heurck (1880 –1885).

Original description

Kützing (1844): 71, pl. 5, fig. 7. 1–2, reproduced in Fig. 1 View Figs 1–8

C. minuta , elliptico-oblonga, densissime aggregata, laevissima; limbo nullo. An Callithamnion cruciatum in den Lagunen von Venedig ! (Laguna Veneta, Italy) - Länge 1/150–1/140”. – “fig. 1. geglüheten Exemplare, fig. 2. aufgeweichte Exemplare”.

Emended description by Van Heurck

Van Heurck (1896: 290, pl. 29, fig. 823) after observation of the original specimen (F.T. Kützing no. 259 in Van Heurck collection): “valves small, elliptic, finely striate; transverse striae about 40 in 1 c.d.m., reaching to the raphe, formed of puncta, distant and consequently capable of forming longitudinal lines undulate or decussate (according to the direction of the illumination). Raphe robust; central nodule elongated into a narrow acute stauros. Length, 1.5 to 2 c.d.m. Breadth, 1 c.d.m. Marine. North Sea”.

Type material

“An Callithamnion cruciatum in den Lagunen von Venedig ” ( Kützing 1844: 71; Kützing 259, Herbarium sheet BM 000905975 , BM 18381 , holotype); BR slide IX-43-A13 (Van Heurck collection, Kützing 259, isotype).

Notes

Van Heurck (1896) after studying material from F. T. Kützing, emended the description and stated that the observed specimen “corresponds to the var. crucifera of Grunow ( H. V. H. Atl.: pl. 20, fig. 20)” ( Van Heurck 1880 –1885: pl. 30, fig. 20) and added “it appears to me right to consider it as the type form”.

LM examination of the type material and completed description

Cf. Riaux-Gobin & Compère (2008): figs 56–57; Figs 15–17 View Figs 15–20 from BM 18381, Figs 18–20 View Figs 15–20 from slide IX-43- A 13.

The frustule is small (ca. 16.4 µm long, 9.7 µm wide) and strongly arched ( RV concave, SV convex). The RV striation is hardly discernible, with ca. 30 striae in 10 µm ( Fig. 18 View Figs 15–20 , arrowhead). The SV areolae are arranged along axial rows in a zig-zag pattern (22–23 rows in 10 µm, Figs 16, 17, 20 View Figs 15–20 ). The helictoglossae are close to the margin and deflected in opposite directions ( Fig. 15 View Figs 15–20 ), the raphe is straight. The SV sternum is narrow and straight, with a small oblong central area. The RV fascia is narrow and half a valve in length.

SEM examination of the Herbarium sheet BM 000905975

The material is very poor and only a broken SV of Cocconeis molesta was observed, with the following morphometrics and features: estimated valve length (> 17 µm), SV stria density (40–42 in 10 µm,

areolae small and transversely oblong), apical SV row of areolae, in a zig-zag pattern (27.5 in 10 µm), SV sternum narrow and thickened in internal view, central area slightly enlarged.

F

Field Museum of Natural History, Botany Department

T

Tavera, Department of Geology and Geophysics

H

University of Helsinki

V

Royal British Columbia Museum - Herbarium

LM

Secçáo de Botânica e Ecologia

BM

Bristol Museum

A

Harvard University - Arnold Arboretum

RV

Collection of Leptospira Strains

SV

Antigua Estación Experimental Agronómica

Kingdom

Chromista

Phylum

Ochrophyta

Class

Bacillariophyceae

SubClass

Bacillariophycidae

Order

Achnanthales

Family

Cocconeidaceae

Genus

Cocconeis

Loc

Cocconeis molesta Kütz. ( Kützing 1844 )

Riaux-Gobin, Catherine, Compère, Pierre, Jordan, Richard W., Coste, Michel & Yesilyurt, Jovita C. 2016
2016
Loc

Cocconeis molesta var. crucifera Grunow ex Cleve (1895: 174)

Cleve P. T. 1895: )
1895
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