Abas R.Ross & P.A.Sims, 1980
Holotype species: Abas wittii (Grunow) R.Ross & P.A.Sims
Publication details: R.Ross & P.A.Sims, 1980: 119
Original publication and holotype designation: Ross, R. & Sims, P.A. (1980). Syringidium Ehrenb., Dextradonator Ross & Sims, nov. gen. and Abas Ross & Sims, nov. gen. Bacillaria 3: 115-127, 2 plates.
Request PDFFossil: This is a genus of fossil species, or a genus with a fossil type species, or a genus the type species of which was originally described as a fossil.
Description: Frustules united in chains, curved in the one known species. Valves circular with poroid areolae occluded by cribra and near the margm and equally spaced from one another, tall elevations and a single labiate process; each elevation fused at the tip with the tip of an elevation of the contiguous valve; labiate process with the tall external part with a barb at its tip. Cingulum consisting of two deep, cylindrical, undivided copulae with conspicuous poroid areolae and one hyaline pleura.
Information contributed by: Oirignal description. The most recent alteration to this page was made on 2025-04-30 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Fourtanier, E. & Kociolek, J.P. (1999). Catalogue of the diatom genera. Diatom Research 14(1): 1-190.
Comments: Ross & Sims (1980) discuss this genus in detail and comment on its systematic position. They tentatively suggest a place in the Hemiauloideae and reinforce this by comparison of its girdle structure with that of Dextradonator. It is a very unusual diatom in that the two elevations are completely fused. We know of only one other group in which a fusion occurs but this fusion is lateral and the setae then separate again distally (i.e. some species of the Chaetoceraceae). A fusion such as in Abas raises interesting points from a morphogenetic standpoint since the separate silicalemmas would need to fuse.
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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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera,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=46626
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 30 April 2025. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 15 June 2025
