Costus zamoranus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Liliopsida Zingiberales Costaceae

Scientific Name: Costus zamoranus Steyerm.
Taxonomic Notes: Costus zamoranus was described by J. A. Steyermark in 1963 based on a collection from 20 years earlier. It was described as a basal flowering species distinguished from other such species only by the differences in the shapes of the leaves and bracts and differences in hairiness. There was no description of the true flowers because his specimen was not in flower. 

It was accepted as a valid species by Dr. Paul Maas in his 1972 monograph and his 1977 follow-up, but the descriptions were incomplete and the species was difficult to distinguish from the similar species, Costus amazonicus (Loes.) J.F. Macbr. and Costus laevis Ruiz & Pavon. There were no photos available resulting in uncertainty in the identifications regarding the few collection records found for this species.

In February 2015, Dave Skinner visited the type locality and other parts of Zamora-Chinchipe Province in Ecuador to clarify the delineation of this species and gather data concerning its population and range. The photos attached to this IUCN assessment have been taken by Dave Skinner to be examples of this species. Additional taxonomic details are included in an article published September 2015 in the quarterly Bulletin of the Heliconia Society International, Vol. 21, No. 3.

This species is a wild relative of cultivated ornamental ‘spiral gingers’, such as Hellenia speciosa (J.Koenig) Govaerts, comb. nov.  (Crepe Ginger) (formerly Costus speciosus Koen ex. Retz.), C. scaber Ruiz & Pav. (Indian Head Ginger), C. comosus (Jacq.) Roscoe (Red Tower Ginger), C. woodsonii Maas (French Kiss), and C. productus Gleason ex Maas (Orange Tulip Ginger).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(ii,iii,v)+2ab(ii,iii,v); D ver 3.1
Year Published: 2015
Date Assessed: 2015-07-22
Assessor(s): Skinner, D.
Reviewer(s): Magos Brehm, J.
Contributor(s): Pitman, N.C., Ulloa Ulloa, C. & Magos Brehm, J.
This species is now determined to be quite rare within its range and found only in moist forest habitats that are being destroyed for farming, livestock and logging.  The species was only found in several very small and widely scattered subpopulations in Zamora-Chinchipe province and this species seems to be quite sensitive to habitat change.

This species has been assessed as Endangered because it occupies an area of occupancy (AOO) of 44 km2 (less than 500 km2, the threshold for EN) that is continually declining due to habitat loss, an extent of occurrence (EOO) of 3,816 km2 (less than 5,000 km2, the threshold for EN), is severely fragmented, and the estimated number of individuals (less than 250) as well as the area, extent and quality of habitat are also continuing declining due to deforestation.
Previously published Red List assessments:

Geographic Range [top]

Range Description:There were only four creditable collection records for this species in three widely separated areas in Ecuador which formed the basis of the previous 2014 IUCN Red List assessment for this species (Skinner 2014). This species was poorly described and little was known of the floral structure or the distinctions between Costus zamoranus and its two closest species, C. amazonicus (Loes.) J.F. Macbr. and C. laevis Ruiz & Pav.. This species was originally described based on a sterile plant, collected in 1943 along the Rio Valladolid near the village of Valladolid in the Mayo-Chinchipe region of Zamora-Chinchipe province. Population estimates were based only on these four collection records and the assessment was based on data available concerning habitat destruction in the region.

In February 2015 this assessor, accompanied by Marco Jiménez Villalta and his son Marco Jiménez León, visited the type locality to look for this species, obtain more a complete description and photos, and determine remaining population, distribution, habitat and threat status. In the small forest remnant across the river from Valladolid about 12 plants of this species were seen. The adjoining Mayo-Chinchipe valley, and many other areas of Zamora-Chinchipe Province within the altitude range for the species were also visited.

The species was observed in several other parts of Zamora-Chinchipe Province, but it is quite rare and widely scattered. The observations from this field work have been added to the documented collections found in GBIF and used to recalculate the area of occupancy (AOO) and the extent of occurence (EOO) for this assessment.

Within the EOO and adjoining region, the following localities with suitable altitudes and forests were surveyed, but this species was not found in these areas:
  • Along the Rio Valladolid at higher altitudes upriver from the type locality.
  • Many parts of the Mayo-Chinchipe valley south of Palanda to Aqua Dulce, Zumba, San Andres, and along Rio Isimanchi.
  • Along both the old road and new road between Loja and Zamora.
  • Forested area NW of Zamora.
  • Parque Nacional Podocarpus - all trails at the northern entrance and along the Rio Bonbuscaro.
  • Upper Rio Numbami area.
  • Upper Rio Yacuambi area.
  • Quebrado Cuzuntza and Alto Timbara.
  • Along logging trail south of Guayzimi in the Rio Nangaritza area.
  • Along the Rio Numbaime and El Zarza area.
The absence of this species in the above localities led to our conclusion of the rarity of this species and was taken into account in determining the EOO and in selecting a 2 km square for the AOO calculation.

Using GeoCAT, the EOO has been recalculated at 3,816 km2 and the AOO)at 44 km2 using a 2 km square for each collection/observation site. This is a reduction from 5 km squares to 2 km squares based on our 2015 field observations of the loss of habitat and the species' apparent dependency upon suitable habitat.

Countries occurrence:
Additional data:
Estimated area of occupancy (AOO) - km2:44Continuing decline in area of occupancy (AOO):Yes
Estimated extent of occurrence (EOO) - km2:3816
Lower elevation limit (metres):900
Upper elevation limit (metres):1700
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:During the February 2015 field work, population counts were taken at all sites where the species was found. Most localities had only one to three plants growing and there were only nine sites where the species was found. A total of 33 plants were observed at these nine sites. There were many other localities visited where the species might be expected but none were found. Marco Jiménez Villalta, who lives in Zamora and has been exploring the forests of the region for over 20 years, knows Costaceae very well, but does not recall seeing this species in other places. Based on his knowledge of the plants of the region and the observations by this assessor in February 2015, the total population size is estimated at no more than 200 mature individual plants.

Based on the small isolated subpopulations that were observed and the many other surrounding localities that were searched and were lacking this species, this total population should be considered as severely fragmented.

The population size is estimated to be decreasing at a rate of about 10% per 24 year period (three generation lengths past, present and future) due to loss of habitat.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:200Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:This species appears to be very sensitive to habitat. In the type locality and surrounding area this species was found only in moist forest remnants growing in coarse sandy soil. It was not found in open areas or in areas of secondary forest. It was found at elevations ranging from 900 to 1,700 m asl. The altitude at the type locality of Valladolid was reported as 2,000 m asl, but found to be in error.

n the Rio Nangaritza area plants were found with some differences from the form seen at the type locality, but are included here as belonging to Costus zamoranus. The soil here is completely different, a sticky grey clay soil, but here also it was only growing in moist forested areas. This area is part of the geologically distinct Cordillera del Cóndor. It is possible that these plants will be determined in the future as a separate variety or subspecies of Costus zamoranus due to these differences. 
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: There is currently no known use or trade unique to this species although other species of Costus are used as ornamentals and as medicinals by native peoples. This species is a wild relative of, and potential gene donor to, other species of ornamental Costus that are cultivated and sold in the horticultural trade.

Threats [top]

Major Threat(s): The primary threat is habitat loss, as described for the locality in Canton Limon-Indanza where this species was once found in forest remnants between pastures and where the area is used for subsistence farming. During the 2015 field work, it was found that deforestation is continuing in the region of the type locality, with a new paved highway nearly completed as far south as Zumba. In the previous assessment (Skinner 2014) it was suspected that the species might be present in the protected area of the Podocarpus National Park and in a sparsely settled area of mountainous terrain between Valladolid and Zamora, but this now seems less likely as we (D. Skinner, M. Jiménez Villalta and M. Jiménez León) did not find it in the northern part of the park or in the Alto Numbami area which has good forest at similar elevations. The only protected area where we (D. Skinner, M. Jiménez Villalta and M. Jiménez León) saw plants presumed to be this species is the Reserva Maycu which is across the Rio Nangaritza in the Cordillera del Cóndor. As noted earlier, the plants found here are of a different form from the ones at the type locality.

Conservation Actions [top]

Conservation Actions: Currently there are no known conservation actions in place for this species, in situ or ex situ. Seeds and stem cuttings or rhizome divisions should be taken from both colour forms found at the type locality and also from the form at the Reserva Maycu locality, then placed and monitored in the dedicated conservation area that is already established near the ranger station of the Podocarpus National Park which is located within the extent of occurrence (EOO) near the town of Zamora. Ex situ conservation of these forms in botanical gardens should also be undertaken as a backup. Seeds of all forms of the species should also be deposited in genebanks to preserve the genetic diversity.

Citation: Skinner, D. 2015. Costus zamoranus. The IUCN Red List of Threatened Species 2015: e.T45121A69569762. . Downloaded on 21 August 2018.
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