Costesia macrocarpa

Taisha is again the author, and she scribes:

Today’s image of Costesia macrocarpa is courtesy of Felipe Osorio-Zúñiga (aka Efe@Flickr), who shared it via the Botany Photo of the Day Flickr Pool after taking the photograph in September of 2012. Thanks Felipe!

Costesia macrocarpa of the Gigaspermaceae is the only species within its genus. The genus Costesia was described in 1917, and the specific epithet macrocarpa was published in 1836, but it wasn’t until 2009 when the two names were united (see: Santoni, Miserere, Buffa. 2009. Costesia macrocarpa comb. nov. for Funaria macrocarpa (Gigaspermaceae). The Bryologist. 112(2): 287-289 for full explanation). The epithet macrocarpa had been assigned to four different genera since first being applied in 1836 by Schimper (as Pottia macrocarpa) from the 1830 original collection of this moss species by Italian naturalist Carlo Bertero. Barring a rare situation (e.g., some other species in the genus already bearing the same epithet), the epithet macrocarpa should continue to be used, no matter what genus it is assigned to based on the principle of priority.

The genus name Costesia was assigned to what-was-thought-to-be a different taxonomic entity by Thériot in 1917, when he described Costesia spongiosa. However, the description and illustrations of Thériot’s Costesia spongiosa were determined (in the 2009 paper) to match the entity described by Schimper in 1836. If this entity is considered to be in its own genus (which it seems there is agreement on), then the principle of priority is again applied. Thériot’s use of Costesia was the first valid instance of such naming. Combining the two instances of the priority-taking names yields Costesia macrocarpa.

Costesia macrocarpa is a bryophyte endemic to Valparaiso, Santiago, and Cachapoal in central Chile. It is classified as vulnerable due in part to habitat loss and a restricted range. This small moss species has thick-walled leaf cells, synoicous inflorescences (where the archegonia and antheridia are mixed within the same inflorescence), filiform perigonial paraphyses (modified leaves around the male organs) without inflated terminal cells, gynostomous capsules (lacking a peristome), large spores that are greater than 50 µm (hence Gigaspermaceae), stomata that are enclosed by two guard-cells and an exothecium (external layer) that is rugose-spongiose (wrinkled and somewhat spongy).

If, like myself, you can never seem to remember all of the biological terms associated with bryophytes, I suggest looking at the Flora of Australia’s Flora of Australia Glossary for Mosses, compiled by Helen P. Ramsay.

Costesia macrocarpa

2 responses to “Costesia macrocarpa”

  1. Elizabeth Revell

    What a cute little spore body! And an excellent write-up, too.

  2. Jessica

    I think they should rename it Costesia party balloons!
    It’s adorable.
    Thanks so much for posting such a great photo and in-depth info about this lovely plant.
    I love this site. There’s so much to learn.

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