This page contains photos and description of a species, form or cultivar of Costaceae.

Gingersrus Database Taxon ID 4609

Costus geothyrsus


OLD NAME: Costus geothyrsus

NEW NAME: Costus geothyrsus

NAME CHANGE NOTES:

FULL SCIENTIFIC NAME: Costus geothyrsus K.Schum.

STATUS : accepted

CONTINENT: Neotropical

FIELD OBSERVATIONS:(If field observations are available, you can click on the link to open in a new window.)
FIELD OBSERVATIONS

PHOTOS:(If photos are available, you can click on the link to open in a new window.)
GOOGLE PHOTO ALBUM

SYNONYMS:


BOTANICAL NOTES:
Costus geothyrsus is an accepted species of neotropical Costus that was described by Karl Schumann in 1904. The type specimen was from El Recreo in Manabi province of western Ecuador collected by Van Eggers in 1893. The holotype was destroyed in Berlin but a lectotype is at Kew. The species is described as a (usually) basal flowering plant that can be compared with Costus pulverulentus, having red non-appendaged bracts and tubular flowers with reddish orange corolla and yellow labellum. It has a stamen that far exceeds the labellum as in C. pulverulentus, but differs by the shape of the leaves (large and broad with acute to rounded base) and the exceedingly long corolla lobes (reported up to 100 mm long!Costus geothyrsus is found only in the western provinces of Ecuador and adjoining Narińo in Colombia. These areas have a long, distinct dry season and flowering is predominantly in the rainy season. I developed an IUCN Red List assessment for this species which calculated to being Critically Endangered based on the rarity of this species and the extreme loss of habitat in western Ecuador.

I had never seen a photo of the flower until I contacted Swedish botanist Bertil Stahl who has been working for many years at the reserve at Hacienda Clementina in southern Ecuador - one of the places where this species is recorded. Based on these photos, the flower is reddish-orange with very long corolla lobes extending beyond the stamen and labellum. The stamen has a very short anther crest with just a short distance from the thecae to the apex of the stamen, and protruding several mm beyond the yellow labellum, similar to C. pulverulentus. The bract margins are not fibrous (as in C. pulverulentus) and the nectar callus is darker red instead of yellow or green. So the plant is clearly distinguishable from C. pulverulentus and by more than just the basal flowering habit or size of the flowers and leaves.

In February 2015 I went to Hacienda Clementina near Caluma, Bolívar, Ecuador. My guide there, Rene Vargas was able to get permission for us to enter one part of the reserve. I did not find this species in flower but I did find one small plant in the reserve that is consistent with the species and a larger plant cultivated at the Hosteria where Dr. Stahl usually stays. More importantly to me, I was able to confirm that this species cannot be found in the other small forest fragments in the region, thus supporting its status as a critically endangered species.

In 2016 I saw an observation record on iNaturalist that appears to me to be Costus geothyrsus. It was posted by "permaculturcaimito" from a photo by Bryan Arturo. The locality: Caimito is a small community belonging to the parish of Quingue, in the province of Esmeraldas in northwest Ecuador. Our community is located in one of the most biodiverse and ecologically privileged places in the world. It is one of the last remnants of Tropical Rainforest (Chocó) on the coast of Ecuador. It is located near the Mache Chindul Ecological Reserve and is part of the Galera-San Francisco Marine Reserve, the first marine reserve established along the continental coast of Ecuador. Two additional Inaturalist observations have been recorded since then and they clearly show the extended stamen and the long corolla lobes that distinguish this species as well as the basal flowering habit. The link at https://www.inaturalist.org/observations?subview=map&taxon_id=436029 (not my own observations) show this very well.

A partial phylogeny was completed by Eugenio Valderrama and his associates in the Chelsea Specht Lab at Cornell University and was published in the journal Frontiers in Plant Science in September 2022. DNA has been extracted from one of the Bertil Stahl collections at Hacienda Clementina (Cerro Semama) and this shows Costus geothyrsus to be well separated from C. pulverulentus in an older lineage with C. cordatus from western Colombia.

HORTICULTURAL NOTES:
Based on information at the Botanic Gardens Conservation International (BGCI) this species is not in ex situ cultivation at any reporting botanical gardens. This species really needs to be collected and conserved as it is quite rare in the wild.

ACCESSIONS:Click links (if any) to see details of individual collections. R3343- R3347-


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Photos (if available) of Taxon ID 4609
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Costus geothyrsus, photo from Maas, 2916 ECU U0999295.jpg - Click to see full sized image
Photo# 215 Accession# R0
Costus geothyrsus, photo from Maas, 2916 ECU U0999295.jpg


Costus geothyrsus, photo from Bertil Stahl at type locality Cerro Semama, Ecuador - Click to see full sized image
Photo# 216 Accession# R0
Costus geothyrsus, photo from Bertil Stahl at type locality Cerro Semama, Ecuador


Costus geothyrsus type specimen - Click to see full sized image
Photo# 486 Accession# R0
Costus geothyrsus type specimen


Costus geothyrsus type specimen - Click to see full sized image
Photo# 487 Accession# R0
Costus geothyrsus type specimen