Gyrosigma acuminatum (Kützing) Rabenhorst 1853
Gyrosigma acuminatum (Kützing) Rabenhorst
SEM - 16 July 2011. F.A.S. Sterrenburg
Gyrosigma acuminatum (Kützing) Rabenhorst 1853: 47, pl. 5: fig. 5a
Status of Name
This name is of an entity that is currently accepted taxonomically.
Frustulia acuminata Kützing
Type locality: süssen Wassern [sweet waters, presumably Germany]; (Kützing 1834: 555) Notes: G.C. 14188a, ANSP and BM 78084 (syntype) [Sterrenburg pers.comm.]
Origin of Species Name
Participle A (Latin), acuminate, i.e. tapering gradually or abruptly from inwardly curved sides into a narrow point (Stearn 1973).
This is a freshwater species.
Valve moderately sigmoid, slender to somewhat more broadly lanceolate with fairly obtuse or subacute ends, 70-180 µm long, 12-24 µm wide. Raphe sternum with minimal double curvature, almost straight for half its length, practically median except slightly eccentric near the ends, raphe angle +3 to +8 degrees. Central raphe fissures crook-shaped, oppositely deflected to either the convexity or concavity of their raphe sternum (dimorphic deflection type). Central area oval, not rotated. Terminal areas unilaterally dilated funnels in semilateral position. A crescent of minute apical microforamina runs around the apex in the hyaline terminal area, at the limit of visibility in the LM. Longitudinal striae 19-24 in 10 µm, markedly closer together at the margin of the valve (SEM), transverse almost equally fine or very slightly coarser.
Very common in fresh to very slightly brackish waters, probably cosmopolitan and personally (Sterrenburg) observed in samples from Europe, the USA, New Zealand and South Africa.
Created: 11 April 2002 by M.D. Guiry.
Last updated: 02 June 2023
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Linking to this page: https://www.algaebase.org/search/species/detail/?species_id=32031
Cite this record as:
G.M. Guiry in Guiry, M.D. & Guiry, G.M. 02 June 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 11 December 2023