Haqius


Classification: Mesozoic -> Heterococcoliths inc sedis -> placoliths inc sedis -> Haqius
Sister taxa: Ellipsolithus, Haqius, Markalius, Prolatipatella, Repagulum,

Distinguishing features: Unicyclic, elliptical and circular placolith coccoliths with a narrow or closed central area and a characteristically dark gray (low birefringence) XPL image.


Daughter taxa: (blue => in age window 0-800Ma)
Medium to large unicyclic circular placolith with a narrow or closed central area. Under LM XPL the shields appear pale gray crossed by diagonal extinction lines, with a darker central region, and the numerous individual elements are usually visible.
Large (>7.0 µm) unicyclic placolith with a narrow or closed central area. Under LM XPL the shields appear gray and the numerous individual elements are usually visible. The proximal shield is significantly smaller than the distal and is often clearly distinguishable.
Small (<6.5 µm), elliptical, unicyclic placoliths with a narrow or closed central area. Under LM XPL the shields appear gray and individual elements are usually visible. Some specimens possess small bar-like structures that cross the narrow central area.
Specimens not identified to species level

Taxonomy:

Citation: Haqius Roth, 1978
Rank: Genus
Type species: Coccolithites circumradiatus Stover, 1966 designated by Roth (1978).
Synonyms: Esgia Worsley 1971

Farinacci & Howe catalog pages: Haqius * , ,

Distinguishing features: Unicyclic, elliptical and circular placolith coccoliths with a narrow or closed central area and a characteristically dark gray (low birefringence) XPL image.


Morphology remarks: Worsley (1971) described the genus Esgia based on a specimen similar to Haqius circumradiatus. We use Haqius here as it alone has consistently been used for coccoliths of this group.

Geological Range:
Last occurrence (top): in upper part of Campanian Stage (67% up, 75.9Ma, in Campanian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Tithonian Stage (62% up, 147.7Ma, in Tithonian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs

Roth, P. H. (1978). Cretaceous nannoplankton biostratigraphy and oceanography of the northwestern Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 44: 731-760. gs

Stover, L. E. (1966). Cretaceous coccoliths and associated nannofossils from France and the Netherlands. Micropaleontology. 12: 133-167. gs

Worsley, T. R. (1971). Calcareous nannofossil zonation of Upper Jurassic and Lower Cretaceous sediments from the Western Atlantic. In, Farinacci, A. (ed.) Proceedings of the Second Planktonic Conference Roma 1971. Edizioni Tecnoscienza, Rome 2: 1301-1321. gs


nannotaxlogo400px

Haqius compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 24-7-2019

Taxon Search:
Advanced Search

Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10490 Go to Archive.is to create a permanent copy of this page - citation notes



Comments (0)

No comments yet. Be the first!

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics