AMPHIBIAWEB
Nectophrynoides asperginis
Kihansi Spray Toad
family: Bufonidae

© 2013 John P. Clare (1 of 4)
Conservation Status (definitions)
IUCN (Red List) Status Extinct in the Wild (EW)
CITES Appendix I
Other International Status Critically Endangered
National Status None
Regional Status None

 

View distribution map using BerkeleyMapper.

   

From the Encyclopedia of Life account:

Etymology

From the Latin 'aspergo' meaning spray or sprinkling, referring to the water spray that this species was dependent upon before its extinction in the wild.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Summary

Nectophrynoides asperginis, the Kihansi Spray toad, is an ovoviviparous species that was known only from the Kihansi River Gorge in the Udzungwa Mountains of Tanzania before it went Extinct in the Wild.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Distribution

This species was only known from the Kihansi Falls, in the Kihansi Gorge, in the Udzungwa Mountains, eastern Tanzania, and its distribution was greatly limited, covering an area of less than two hectares around the Kihansi Falls (Channing et al., 2009). Examination of of additional waterfalls on the escarpment of the Udzungwa Mountains have not located any additional populations (Channing et al. 2006).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Size

Males are 15-17 mm and females 18–20 mm in snout-vent length (Harper et al., 2010).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Diagnostic Description

A small frog. The dorsum is yellow-brown with a pair of distinctive brown stripes that run from behind the eye to the groin. Some irregular dark markings may be present on the dorsum. There are no dark markings on the ventral surface. The tympanum is not visible. The snout is short, and the eyes are large with horizontal pupils. This species lacks distinct parotid glands. Finger tips are rounded and not expanded. Toes and fingers are webbed (Harper et al., 2010).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Habitat and Ecology

It lived only in soaked herbaceous vegetation in the spray zone of the Kihansi Falls at elevations of 600–940 m (Channing et al., 2009; Harper et al., 2010).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Associations

Nectophrynoides asperginis tested positive for Batrachochytrium dendrobatidis in Kihansi Gorge, Tanzania in 2003 (Weldon & Du Preez 2004).

Arthroleptis stenodactylus, Schoutedenella xenodactyla, Nectophrynoides tornieri, and Arthroleptides spp. are found sympatrically (NORPLAN 2002, cited in Lee et al. 2006).

It is known from stomach contents that wild Kihansi spray toads prefer dipterids and dipterid larvae but also eat acarine mites and springtails (Lee et al. 2006).

The impact of predation by safari ants (Dorylus sp.) and crabs (Potomonautes sp.) is unknown (Channing et al. 2006).

Batrachochytrium dendrobatidis notably contributed to the recent decline of the Kihansi spray toad, Nectophrynoides asperginis (Goldberg et al., 2007).


Authors: Zimkus, Breda; Bergmann, Travis
License: http://creativecommons.org/licenses/by-nc/3.0/

Population Biology

It was formerly abundant in a tiny area, with a population of approximately 17,000 animals with natural fluctuations in the population size. The population increased until May 1999 when numbers subsequently dropped during the course of 2001 and 2002 with estimates of 11,000 individuals up until March 2002 (Channing et al., 2006). Populations increased again with a total population estimate of 20,989 individuals in June, 2003. The population then went into steep decline, and by mid-January 2004, only three individuals could be seen and just two males were heard calling. There were a handful of records of calling animals during the rest of 2004, one unconfirmed report from May 2005 (CBSG 2007), and no records of any individuals since, despite surveys (Channing et al., 2009).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Activity and Special Behaviors

In captivity, this species has been observed feigning death and ejecting water from its bladder when disturbed (Lee et al., 2006).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Advertisement Call

Two calls are known – an advertisement call and an aggression call. Calls can be heard during the day as well as at night. The advertisement call is described by Channing and Howell as “a single note with 1–4” pulses and the aggression call is “a series of advertisement calls.”


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Reproduction

Fertilization is internal, and the females retain the larvae internally in the oviduct until the toadlets are born (Channing et al., 20006). During amplexus, the male clasps the female under the armpits and places his feet on top of her thighs so that he does not touch the rock surface. Eggs are 2.4 mm in diameter (Poynton et al., 1998). Channing et al. report that the clutches range form 10-16 with an average of 11; Harper et al. (2010) and Lee et al. (2006) report slightly larger sized clutches with 16-18 young and 24-28 young, respectively.


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

IUCN Red List Category and Justification of Conservation Status

The IUCN Red List (2010) categorizes this spcies as Extinct in the Wild because no self-sustaining population exists in the wild, but the species survives in captivity (Channing et al., 2009).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Threats

The decline and extinction of this species is likely related to the Lower Kihansi Hydropower Project, which constructed a dam upstream on the Kihansi River in 2000, cutting off 90% of the water flow to the gorge. This subsequently reduced the volume of spray, particularly in the dry season, as well as altering the vegetational composition (Channing et al., 2009). An artificial gravity-fed sprinkler system was set up to mimic the natural spray of the Kihansi ecosystem with the remaining water flow, but the system was not ready by the time the water was cut off in 2000. The ecosystem had already dried up by the time the sprinklers were activated nine months later. The artificial sprinkler system also later failed during the dry season of 2003. At this same time, the fungal disease chytridiomycosis was confirmed in dead animals. Chytridiomycosis was believed to be responsible for the final population crash; drought caused by the failure of the sprinkler system also may have rendered the frogs susceptible to the disease due to stress. It was also reported that the 2003 crash coincided with a brief opening of the dam's floodgates to flush sediments; water tests revealed that there were pesticides used in maize farming operations upstream present in concentrations sufficient to kill the toads (Krajick, 2006).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/

Conservation Actions and Management

This species is likely extinct in the wild, with the last confirmed sighting in 2005. The small area of habitat used by the toads was severely altered by the construction of a dam on the Kihansi River as part of the Lower Kihansi Hydropower Project (see Threats). A fungal pathogen, chytridiomycosis is also thought to have contributed to the ultimate population crash. Some toads were collected from the wild population and are now housed at captive breeding facilities in the Toledo and Bronx Zoos (Harper et al., 2010). The captive populations have fluctuated as husbandry problems have been encountered and addressed (animals were initially plagued with various infections and nutritional deficiencies); ex situ colonies were comprised of a total of 460 individuals on February 12, 2007 (CBSG, 2007). Reintroduction efforts should be preceded by an assessment of the species' habitat status and efficiency/operationality of the artificial sprinkler system currently in place. Breeding facilities for this species are also currently being developed in Tanzania (Harper et al., 2010). This species was not known from any protected areas (Channing et al., 2010).


Author: Zimkus, Breda
License: http://creativecommons.org/licenses/by-nc/3.0/