Thallophyca

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Thallophyca
Temporal range: Ediacaran
~635–551  Ma [1]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Archaeplastida
Division: Rhodophyta
Class: Florideophyceae
Order: Corallinales
Stem group: Corallinaceae
Genus:† Thallophyca
Zhang, 1989
Type species
†Thallophyca ramosa
Zhang, 1989
Species
  • †T. ramosaZhang, 1989 [2]
  • †T. phylloformisZhang & Yuan, 1992 [3]
  • †T. corrugataZhang & Yuan, 1992 [3]
Synonyms
  • T. ramosa
    • †T. simpliciaZhang, 1989 [2]

Thallophyca is a non-mineralized branching alga from the Ediacaran period of China. Two distinct species are known, T. ramosa and T. corrugata.

Contents

Discovery

Fossil material of Thallophyca was found in the Doushantuo Formation, Guizhou Province of South China and formally described in 1989. [2]

Etymology

The generic name Thallophyca derives from a truncated Greek word Thallus , commonly used for algae; and phyc , to mean "seaweed". [2]

The specific name of T. ramosa derives directly from the Latin word of the same spelling, ramosa , to mean "branched", in reference to the appearance of its branching thallus. [2] The specific name of T. corrugata derives directly from the Latin words of the same spelling, corrugata , to mean "wrinkly", in reference to the wrinkly appearance of the thallus. And the specific name of T. phylloformis derives from the Greek word phyllo , to mean "leaf"; and the Latin suffix word -formis , to mean "shape", in reference to the leaf-like shape of its thallus. [3]

Description

Thallophyca are ellipsoidal alga growing up to 3.5 mm (0.14 in) in height and 20 mm (0.8 in) in width, with the outer portions of their thallus being enlarged, with notable differentiation into an outer cortex and an inner medulla. [4] [5] The outer cells of the cortex are slightly elongated and spheroidal to polyhedral in shape, and oriented along the thallus, meanwhile the inner cells of the medulla diverge outwards in rows. [5] These inners cells are similar to pseudoparenchyma, due to their tightly packed nature. [5] Some specimens of Thallophyca also show possible reproductive cells within the thallus in the form of clustered islands of larger cells which may be cystocarps, sorus-like structures, and cavities, which are suggested to be similar to conceptacles. [4]

Due to the overall appearance of Thallophyca, it has been compared to extant forms of Coralline algae, and as such has been postured to be an early stem group corallinalean red alga. [4] [5] It was also most likely a benthic alga, inferred from how its lobate protrusions and tissues grew, which can be seen in the large lobes of Thallophyca specimens, which radiate from a centre point. [5]

Taxonomy

To date, Thallophyca contains three valid species, and one invalid species, which are as follows:

SpeciesAuthorityType localityNotesRefs
Thallophyca ramosa Zhang (1989) Doushantuo Formation, South ChinavalidType species [2]
Thallophyca simplicia Zhang (1989) Doushantuo Formation, South ChinainvalidSynonym of T. ramosa. [2] [5]
Thallophyca corrugata Zhang & Yuan (1992) Doushantuo Formation, South Chinavalid [3]
Thallophyca phylloformis Zhang & Yuan (1992) Doushantuo Formation, South Chinavalid [3]

See also

References

  1. ↑ Jiang, G.; Shi, X.; Zhang, S.; Wang, Y.; Xiao, S. (2011). "Stratigraphy and paleogeography of the Ediacaran Doushantuo Formation (ca. 635-551 Ma) in South China". Gondwana Research. 19 (4): 831–849. Bibcode:2011GondR..19..831J. doi:10.1016/j.gr.2011.01.006.
  2. 1 2 3 4 5 6 7 Zhang, Yun (1989). "Multicellular thallophytes with differentiated tissues from Late Proterozoic phosphate rocks of South China". Lethaia . 22 (2): 113–132. doi:10.1111/j.1502-3931.1989.tb01674.x.
  3. 1 2 3 4 5 Yun, Zhang; Xun‐Lal, Yuan (January 1992). "New data on multicellular thallophytes and fragments of cellular tissues from Late Proterozoic phosphate rocks, South China". Lethaia. 25 (1): 1–18. doi:10.1111/j.1502-3931.1992.tb01788.x.
  4. 1 2 3 Xiao, S.; Knoll, A. H.; Yuan, X.; Pueschel, C. M. (2004). "Phosphatized multicellular algae in the Neoproterozoic Doushantuo Formation, China, and the early evolution of florideophyte red algae". American Journal of Botany. 91 (2): 214–227. doi: 10.3732/ajb.91.2.214 . PMID   21653378.
  5. 1 2 3 4 5 6 Shang, Xiaodong; Liu, Pengju (January 2022). "Diverse multicellular algae from the early Ediacaran Doushantuo chert nodules and their palaeoecological implications". Precambrian Research. 368 106508. doi:10.1016/j.precamres.2021.106508.
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