Achnanthidium craterianum Marquardt & C.E.Wetzel, 2023
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publication ID |
https://doi.org/ 10.5252/cryptogamie-algologie2023v44a6 |
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DOI |
https://doi.org/10.5281/zenodo.8385535 |
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persistent identifier |
https://treatment.plazi.org/id/8A2887BC-FFD3-1E39-DE77-F94AFE13D3EE |
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treatment provided by |
Plazi |
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scientific name |
Achnanthidium craterianum Marquardt & C.E.Wetzel |
| status |
sp. nov. |
Achnanthidium craterianum Marquardt & C.E.Wetzel , sp. nov.
( Figs 5-8 View FIG View FIG View FIG View FIG )
HOLOTYPE. — Brazil. São Paulo, SP, Parelheiros District, Colônia crater, 23°52’S, 46°42’20”W, 900 m a.s.l., from sample 4268- 69 cm liner depth (c. 1.37 Ma; 4311 composite depth) of the COL17-3 View Materials sediment core, VIII.2017, M.-P. Ledru & A.O. Sawakuchi (SP[ SP514.067 ]!). GoogleMaps
ISOTYPE. — Same data as holotype ( BR [ BR4737 ]!) GoogleMaps .
TYPE LOCALITY. — Brazil. São Paulo, SP, Parelheiros District, Colônia crater, 23°52’S, 46°42’20”W, 900 m a.s.l.
ETYMOLOGY. — The Latin name craterianum refers to the Colônia Basin geomorphological structure where the sample was collected.
ECOLOGY AND DISTRIBUTION. — Achnanthidium craterianum Marquardt & C.E.Wetzel , sp. nov. was abundant in the core (60% relative abundance). Accompanying taxa included mainly Aulacoseira ambigua (28%) and Staurosira sp. 1 (5%) as dominant species.
DESCRIPTION
LM observations ( Fig. 5 View FIG )
Frustule girdle in view is rectangularly arched,with pointed apices slightly curved ( Fig. 5 View FIG AI, AJ). Valves linear to linear-lanceolate, with margins almost parallel to only slightly widening toward the central area. Sub-capitate to capitate apices, protracted ( Fig. 5 View FIG A-AH), facing opposite directions ( Fig. 5 View FIG B-O, R-AH); 8.5-19.0 µm long, 2.0-2.5 µm wide. Raphe valve: narrow to faintly lanceolate axial area toward the central area; rounded central area, with 2-4 shortened striae on both sides of the valve ( Fig. 5 View FIG A-U). Straight raphe filiform. Transapical striae slightly radiating throughout the entire valve, more spaced in the central area, becoming denser and more strongly radiating toward the apices ( Fig. 5 View FIG A-U); 32-33 in 10 µm. Rapheless valve: narrow, linear axial area, sometimes faintly lanceolate toward the central area; absent central area or narrow lanceolate ( Fig. 5 View FIG V-AH). Transapical striae slightly radiate throughout the entire valve, more spaced in the central area, becoming denser towards the apices; 40-42 in 10 µm. Rectangular arcuate girdle view, with pointed apices slightly recurved to the rapheless valve( Fig.5 View FIG AI-AJ).
SEM observations ( Figs 6-8 View FIG View FIG View FIG )
Raphe valve: raphe prolonged after the striae, terminating on the border between the valve face and mantle ( Fig. 6 View FIG A-C). Central and terminal raphe fissures are straight and slightly expanded at the endings ( Fig. 6 View FIG A-D). Striae composed of 2-3 rounded areolae, becoming denser toward the apices ( Fig. 6 View FIG A-C). Internally, proximal raphe endings slightly deflected in opposite directions, distal endings terminating in small helictoglossae ( Fig. 6 View FIG A-C). Rapheless valve: very narrow axial area, lanceolate towards the central area ( Figs 6E, F View FIG ; 7D View FIG ). Striae composed of 2-3 rounded to slit-like areolae ( Fig. 6E, F View FIG ). Mantle with one row of slit-like transapically orientated areolae ( Figs 6F View FIG ; 8 View FIG A-C).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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