Hyalolithus neolepis


Classification: non_cocco -> Haptophytes -> Prymnesiales -> Prymnesiaceae -> Hyalolithus -> Hyalolithus neolepis
Sister taxa: H. neolepis,

Taxonomy:

Citation: Hyalolithus neolepis Yoshida et al., 2006
Rank: Species
Basionym: Hyalolithus neolepis Yoshida et al., 2006
Variants: There appears to be significant variation in the width of the rim of scales, and in the number and size of perforartions. Distinct sub-taxa have not, however, been recognised, (Jordan et al. 2016).
Synonyms: Prymnesium neolepis (Yoshida et al. 2006) Edvardsen, Eikrem & Probert in Edvardsen et al. 2011
Notes & discussion: Edvardsen et al. (2011) recommended transferring the species into Prymnesium on molecular genetic grounds - they showed that it falls within the main clade of Prymnesium species. However the formation of siliceous scales in this species is in our opinion a fundamental difference which needs to be reflected in the taxonomy, see discussion in Jordan et al. (2016, p.444)

Catalog entries: Hyalolithus neolepis

Original description: Cells having at least two forms. Cells non-motile, spherical to subspherical, measuring 8-12 µm, having a posterior vacuole and hyaline hollow space. Two yellowish chloroplasts, each with an immersed pyrenoid. Nucleus central, Golgi body parabasal. Two short flagella, 1.5 µm at longest. A non-coiling haptonema, 12-18 µm long. Periplast covered with two different types of scales. The outer layer consisting of hat-shaped siliceous scales, oval to irregularly ellipsoidal in top view, measuring 5-7 and 4-6 µm across the axes, having many small pores (0.1-0.3 µm) in bulging central area. The brim of scales recurved, not perforated. The inner layer of organic scales, elliptical, measuring 0.6 and 0.4 µm across the axes, with 92-100 rough radial ridges and fine concentric patterns.

Motile phase cell subspherical to pear-shaped. Chloroplasts two, yellowish. Two equal flagella, 15-25 µm long. A non-coiling haptonema, 12-18 µm long. Periplast covered with short spine scales, oval to ellipsoidal in top view, with a maximum area of 2 and 3 µm across the axes, many small pores arranged in a radial pattern (72-120), ridge, marginal thickening.

Type images:


Morphology remarks: Cell spherical-subspherical; Flagella equal, haptonema longer; Scales large, curved, perforate, siliceous plates with radial and concentric ribs; Pyrenoids immersed traversed by thylakoids (Edvardsen et al. 2011)

Geological Range:
Notes: There are only a very few fossil records but convincing Hyalolithus speciemens have been recorded from the Middle Eocene by Abe et al. (2016)
Last occurrence (top): Extant Data source: present in the plantkon
First occurrence (base): within Middle Eocene Sub-Epoch (37.75-47.84Ma, base in Lutetian stage). Data source: Abe et al. in press (cited in Jordan et al. 2016)

References:

Abe, K., Tsutui, H. & Jordan, R. W. (2016). Hyalolithus tumescens sp. nov., a siliceous scale-bearing haptophyte from the middle Eocene. Journal of Micropalaeontology. 35: 143-149. gs

Edvardsen, B., Eikrem, W., Throndsen, J., Sáez, A. G., Probert, I. & Medlin, L. K. (2011). Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta). European Journal of Phycology. 46(3): 202-228. gs

Jordan, R. W. et al. (2016). Observations on the morphological diversity and distribution of two siliceous nannoplankton genera, Hyalolithus and Petasaria. Micropaleontology. 61(6): 439-455. gs

Yoshida, M., Noël, M. -H., Nakayama, T., Naganuma, T. & Inouye, I. (2006). A Haptophyte bearing siliceous scales: Ultrastructure and phylogenetic position of Hyalolithus neolepis gen. et sp. nov. (Prymnesiophyceae, Haptophyta). Protist. 157(2): 213-234. gs


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Hyalolithus neolepis compiled by Jeremy R. Young viewed: 22-9-2019

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