Thalassiosira inlandica Tats.Hayashi 2007

Publication Details
Thalassiosira inlandica Tats.Hayashi 2007: 354, figs 2-40

Published in: Hayashi, T., Tanimura, Y. & Sakai, H. (2007). A fossil freshwater Thalassiosira, T. inlandica sp. nov. (Bacillariophyta), with semicontinuous cribra and elongated marginal fultoportulae. Phycologia 46(4): 353-362, 40 figs.

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Publication date: July 2007

Type Species
The type species (holotype) of the genus Thalassiosira is Thalassiosira nordenskioeldii Cleve.

Status of Name
This name is currently regarded as a synonym of Cyclotella inlandica (Tats.Hayashi) M.L.Julius, K.M.Downey, E.C.Theriot & A.J.Alverson.

Type Information
Type locality: Late Pleistocene lacustrine sediments in the Kathmandu Basin, Nepal (27º40'N, 85º20'E); (Hayashi, Tanimura & Sakai 2007: 354) Holotype: Figs 2, 3 (epitype) 35-34 m depth in the Rabibhawan core (lacustrine sediments); MPC; 04100 (Hayashi, Tanimura & Sakai 2007: 354) Notes: Micropaleontology Collection, the National Science Museum, Tokyo.

Fossil
Described as a fossil.

General Environment
This is a freshwater species.

Description
Frustules discoid in valve view, with diameter 9-34 microns. Pervalvar axis about one-third of the diameter. Valves circular, with a flat valve face (including a slightly depressed centre) and a slanting mantle area. Areolae loculate, each with an external circular foramen and an internal cribrum, arranged in radial rows, 14-17 in 10 microns (in very small valves, up to 10 in 5 microns). Areolation often irregular in the depressed center. Semicontinuous cribra, consisting of linearly arranged pore rows, present on interior of the valve face; continuous cribra present in the mantle area. Valve face fultoportula absent. A circumferential ring of marginal fultoportulae present in the middle of the mantle area. Internally, the marginal fultoportulae with three (sometimes two or four) elongated cowlings (satellite pores); externally, their secondary openings smaller than areolae foramina and surrounded by a conical thickening. Two to four (rarely one) rimoportulae, internally with a stalked labium, taking the place of marginal fultoportulae. Slits of the labia oriented along a valve radius. External openings of the rimoportulae without ornamentation. Siliceous granules sometimes present on the mantle area. Each cingulum composed of four open bands: one valvocopula with an antiligula; others with a ligula and an antiligula. All bands possess circumferential rows of pores along the advalvar edge of each band. Initial valves domed, with diameter 31-36 microns. Loculate areolae radially arranged: from the center to the margin, external foramina gradually increasing in size; internal cribra gradually increasing in density (gradually changing from semicontinuous cribra into continuous cribra). Ring of fultoportulae, with three satellite pores, present near the valve margin. External secondary openings of the fultoportulae near the valve margin but without conical thickenings. Three to five rimoportulae irregularly arranged near the fultoportula ring.

Created: 12 November 2007 by G.M. Guiry.

Last updated: 31 July 2022

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Linking to this page: https://www.algaebase.org/search/species/detail/?species_id=132974

Citing AlgaeBase
Cite this record as:
E.A. Molinari Novoa in Guiry, M.D. & Guiry, G.M. 31 July 2022. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 29 March 2024

 
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