Zosterocarpus abyssicola

Zosterocarpus abyssicola is a species of brown algae endemic to the Galapagos islands.

Zosterocarpus abyssicola
Fig. 9, part of a branch showing the branchlets, young tannin-filled cells, and early gametangium development.
Fig. 10, branch tip showing the acute apex, the intercalary growth zones, and a yellow tannin-filled cell.
Fig. 11, junctions of the forks of two larger branches and a well-developed gametangial area
Scientific classification
Clade: SAR
Phylum: Ochrophyta
Class: Phaeophyceae
Order: Ectocarpales
Family: Chordariaceae
Genus: Zosterocarpus
Species:
Z. abyssicola
Binomial name
Zosterocarpus abyssicola
Synonyms

Distribution

This is a very inconspicuous species and hard to identify, so much that it is only known from its collection of types.[1] The only specimens were collected in 1934 at Post Office Bay by Floreana Island in the Galápagos Islands, and the species is considered endemic to the area.[2] A 2007 search failed to find any further specimens.[1]

Etymology

The specific epithet abyssicola derives from the Greek ἄβυσσος (ávyssos) and Latin -cola, meaning one who inhabits the abyss. However, it has only been found at 55 meters depth,[2] and is photosynthetic, so the name is hyperbole.

Description

The thallus is a light green-brown and 1-2 cm tall.[2] The form is rather diffuse and spreading, without a persistent main axis.[2] The cells of the major branches are thin-walled, cylindrical, and 32 μm in diameter and 58-65 μm long.[2]

The characteristic oval brown cells were assumed to be the sporangia by Taylor,[2] but are special tannin-filled cells.[3] These are scattered throughout the upper thallus, but solitary, measuring about 30 μm in diameter and 68-70 μm long.[2] They contain oval-shaped bodies.[2]

The gametangia are in clusters of 4-6 cells and only 6-8 μm in diameter.[2]

The species lacks phaeophycean "hairs" and the parenchyma is weakly developed.[3] It is more slender than Z. oedogonium, and the brown tannin cells for the former are wider than the rest of the filaments, ad opposed to the same size.[2] Z. ogasawaraensis and Z. australicus lack these special cells.[3] The latter two also have laterals that arise from single sells on the filaments and not from the septa between cells like the former two species.[3]

Ecology

The species is an epiphyte.[2] It is thought to be eaten by sea urchins.[1]

Conservation

It has been evaluated by the IUCN as data deficient, and is one of only fifteen protists evaluated by IUCN.[1] Like Desmarestia tropica, another William Randolph Taylor find from the same expedition, it is threatened by warming ocean temperatures and overgrazing by sea urchins.[1]

References
  1. Miller, Kathy Ann; Garske, Lauren E.; Edgar, Graham J. (1 March 2007). "Zosterocarpus abyssicola" (HTML). IUCN Red List of Threatened Species. 1 March 2007. doi:10.2305/IUCN.UK.2007.RLTS.T63592A12685875.en. OCLC 7375945856. Retrieved 15 August 2018.
  2. Taylor, William Randolph (May 1945). "Pacific marine Algae of the Allan Hancock expeditions to the Galapagos islands" (TIF). Allen Hancock Pacific Expeditions. 12: 79–80, 320–321. LCCN 42021995. OCLC 758261137. Retrieved 16 August 2018.
  3. Kitayama, Taiju (22 November 2013). "Morphology of Zosterocarpus ogasawaraensis sp. nov. (Phaeophyceae, Ochrophyta), a New Marine Deep-water Brown Alga from the Ogasawara Islands, Japan" (PDF). Bulletin of the National Museum of Nature and Science. B. 39 (4): 159–164. ISSN 1881-9060. OCLC 5528941544. Retrieved 16 August 2018.
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