Plagiotropis Pfitzer, 1871, nom. illeg.

Holotype species: Plagiotropis baltica Pfitzer

Publication details: Pfitzer, 1871: 93

Original publication and holotype designation: Pfitzer, E. (1871). Untersuchungen über Bau und Entwicklung der Bacillariaceen (Diatomaceen). In: Botanische Abhandlungen aus dem Gebiet der Morphologie und Physiologie Bd 2. pp. [i]-vi, [1]-189, plus 6 pls. Bonn: bei Adolph Marcus.

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Description: Valve with raphe on a raised ridge without fibulae. In valve view raphe ridge straight or slightly curved but not sigmoid; in girdle view raphe ridge convexly arcuate to bilobate. Valve faces subequal to greatly unequal, often with strong contour lines. Helictoglossae large and elaborate. Polar endings of outer raphe fissure usually curved and slightly expanded, rarely bifurcate, sometimes as rounded pores, usually small. Terminal micropyles usually present. Central area with internal longitudinal crescentic thickenings. Valve areolae with outer foramina slit-like. Valve with one or two scuti, or lacking scuti, according to species. Girdle bands hyaline (non-areolate). Plastids two.

Information kindly contributed by Paddock (1998: 16) but may now be outdated.

Taxonomic status: The taxonomic or nomenclatural status (or both) of this entity is in some way unresolved and requires further investigation.

Gender: This genus name is currently treated as feminine.

Most recent taxonomic treatment adopted: Paddock, T.B.B. (1988). Plagiotropis Pfitzer and Tropidoneis Cleve, a summary account. Bibliotheca Diatomologica 16: 1-152, plus 38 plates.

Nomenclatural note
Illegitimate: not Plagiotropis F.Mueller, Hooker's J. Bot. Kew Gard. Misc. 9: 230. 1857 (Fabaceae), a synonym of Swainsona - (15 February 2021) - M.D. Guiry

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Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=43741

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 27 May 2025. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 01 June 2025