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Costus barbatus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Liliopsida Zingiberales Costaceae

Scientific Name: Costus barbatus Suess.
Taxonomic Notes: The name Costus barbatus has been incorrectly applied in U.S. horticulture to a plant that is actually Costus comosus var. bakeri. This plant, incorrectly identified as C. barbatus is widely cultivated and sold. There are many photos of the plant on the internet creating much confusion. In Australia, the same plant is usually correctly identified as C. comosus.  The true Costus barbatus is not found in cultivation or in photos generally distributed in public.

The true species Costus barbatus is distinguished by having long ligules, fibrous margins to the bracts, bracteoles and calyx, and a densely puberulous corolla.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2c; C2a(i,ii); D ver 3.1
Year Published: 2014
Date Assessed: 2014-02-23
Assessor(s): Skinner, D.
Reviewer(s): Magos Brehm, J.
Justification:
This species is endemic to a small area of Costa Rica in the central valley of San Jose where it was documented in the 1970s to be in the eastern suburbs, an area now completely urbanized with shopping centres, apartments, houses etc. This area is in the watershed of the Rio Torrés which originates on the lower western flanks of the Volcan Irazú. It was originally reported at altitudes between 1,200 and 1,500 metres, but only one small clump of this species has been found at 1,800 metres - outside of its former known altitudinal range. There were mature plants there but no seeds and no seedlings in the area. The species may still exist in the Tapantí National Park, but after searching for this species there and at other suspected locations during several field trips in Costa Rica it was not found.

Geographic Range [top]

Range Description:This species is known from the central valley area of Costa Rica with early collections from the eastern suburbs of San Jose in what is now an urbanized area.  More recently, a few collections were recorded in Parque Nacional Tapantí, in forest patches remaining on the lower slopes of the Volcan Irazú east of San Jose, and possibly one collection to the southwest of San Jose near the town of Palmichal along the trail to Quebrada Londres. The altitudes of these sites range from 1,200 to 1,800 metres.

The identification of this species is often confused with different species, one of which has been widely cultivated as "Costus barbatus", but has been determined to actually be the species Costus comosus.  It is also superficially similar to the species Costus curvibracteatus, which occupies the same altitude range, was more recently described than C.  barbatus, and could have been confused in the collection records.

The following collection sites have been visited and the true Costus barbatus was not found. Those collection records have been discounted by this assessor and are not included in the Extent of Occurrence (EOO) or Area of Occupancy (AOO) calculations. If evidence shows that there are indeed wild populations of this species in those areas, the distribution and population estimates in this assessment would need to be substantially increased.
  • Sites now urbanized near San Jose at Curridabat, San Pedro and along the Rio Torres.
  • El Muneco (this area is now mostly covered by coffee plantations).
  • Collections recorded at Santo Domingo offices of the Instituto Nacional de Biodiversidad (INBio).
  • Collections recorded at very low altitude near La Selva OTS field station.
  • Collections near Monteverde, housed in the herbarium at the University of Georgia San Luis Field Station. (Live flowering plant found and does not fit the description of Costus barbatus)
  • Cerro Nara, near Quepos on the Pacific side (a similar species, C. ricus, was found to be common in this area, but C. barbatus was not found).
In 2011, the species was found by this assessor in a small patch of forest on private property at about 1,800 metres, below Rancho Redondo. An article about this was published in the December 2011 issue of the Heliconia Society International quarterly Bulletin.  It is available on line at http://www.heliconia.org/bulletin/back_issues/2011-Vol17_No4.pdf
Countries occurrence:
Native:
Costa Rica (Costa Rica (mainland))
Additional data:
Estimated area of occupancy (AOO) - km2:24Continuing decline in area of occupancy (AOO):Yes
Estimated extent of occurrence (EOO) - km2:481
Continuing decline in extent of occurrence (EOO):Yes
Continuing decline in number of locations:No
Lower elevation limit (metres):1200
Upper elevation limit (metres):1800
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:In 2011, this assessor made a concerted effort to locate this species in its natural habitat in the eastern suburbs of San Jose, Costa Rica. Using Google Earth, remaining patches of forest at the appropriate altitudes were identified, then visited. All forest patches within the known altitude range of this species were found to be reclaimed coffee fields and no species of Costaceae whatsoever were found in these areas. As noted in the distribution section, this assessor found one very small subpopulation (one clump) of this species in a small creek bed about 5 km east of the known collections and at a higher altitude (1,780 metres) than this species was previously known to exist. This was a large clump with plants at varying levels of maturity from non-flowering plants, to young inflorescences, and including mature inflorescences which normally would contain seeds. No seeds or seedlings were found whatsoever, so it is believed that either the pollinator is extinct or not found at that elevation, or the plant does not maintain sufficient numbers to recruit a pollinator.

Prior to this, the most recent creditable collection record was in 1994 at Parque Nacional Tapanti. This assessor visited the area and the same trail noted in the collection record in 2006 and Costus barbatus was not found there. The other two collection records there were in 1978 and 1974. 

The next prior collection was in 1984, in an area very close to the 2011 observation, to the east of San Jose.

The third area (southwest of San Jose) had one collection record in 1994, and has not been verified by this assessor.

It is difficult to estimate the number of plants still in existence in the wild, but based on the recorded collection data and the many areas searched by this assessor, the number must be very low. Current population size is estimated at  under 50 mature plants.
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:1-50Continuing decline of mature individuals:Yes
Population severely fragmented:Yes
No. of subpopulations:1
All individuals in one subpopulation:Yes

Habitat and Ecology [top]

Habitat and Ecology:This species is described by Paul Maas to occur "along rivers or in wet forest, one specimen from 1,400 meters, the others from unknown elevation". The entire area where this species was found in the 1970s or prior is now completely urbanized or converted to pasture land, or in one case to a coffee growing area.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):8

Use and Trade [top]

Use and Trade: There is no use or trade for this taxon, although a different species incorrectly identified as Costus barbatus is used as an ornamental plant.

Threats [top]

Major Threat(s): The primary threat has been habitat loss in the past, and the few remaining subpopulations (if they exist) continue to be under that threat. The one area where this species was recently found has mostly been converted to pasture land and there is no protected status known that would prevent further loss of habitat in that area.  The other area where this species is believed to exist (above the Orosi valley) has mostly been converted to coffee growing.

Furthermore, the one subpopulation where this species was found recently, all the plants were sterile although they were mature enough that normally would be producing seeds. It is therefore believed that the pollinator is either extinct or at lower altitudes, or the small population was unable to recruit pollinators.

Conservation Actions [top]

Conservation Actions: Currently there is no active in situ or ex situ conservation activity for this species.  Conservation efforts may be confused by the popular use of Costus comosus as an ornamental plant, incorrectly named as this species. The true species Costus barbatus should be collected and conserved in botanical gardens. A more detailed survey of the Tapantí National Park should be conducted and if this species is not found there or found as expected in very limited numbers, it should be reintroduced there in a dedicated area where it can be monitored.

Citation: Skinner, D. 2014. Costus barbatus. The IUCN Red List of Threatened Species 2014: e.T56234708A56234711. . Downloaded on 18 November 2017.
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