This species is known only from the Usambara Mountains in northeastern Tanzania. Within the Usambaras it occurs on both the West and East Usambaras, and on the Magrotto ridge. It occurs down to 180 m asl and up to 1,200 m asl in the East Usambaras, and from 1,300-1,500 m asl in the West Usambaras (S. Loader pers. comm. June 2012). It is unlikely to have a much larger range (S. Loader pers. comm. June 2012). Taking its range as a proxy, its extent of occurrence (EOO) is estimated to be 1,854 km2. It is considered to occur in two threat-defined locations.
Habitat and Ecology
It lives primarily in montane, submontane and lowland forests, but also survives well in secondary habitats, including low-intensity cultivation, perhaps excluding eucalyptus and tea plantations. It is soil-dwelling and has even been found in dry earth. It is oviparous with direct development and is not dependent upon water bodies. Clutch size is less than ten offspring (D. Gower pers. comm. June 2012).
It is a locally abundant species, e.g. data in Gower et al. (2004) and Measey (2004). At Amani Nature Reserve, repeated visits between 1999-2003 found no indication of population change (Measey 2004, Measey and Barot 2006). There is no indication that its population may be severely fragmented.
There are no known major threats, but assuming that soil moisture and temperature maintained by vegetation is important for the species, possible threats include habitat disturbance and conversion caused by intensive agriculture - such as tea plantations (J. Measey pers. comm. November 2012) - deforestation and agricultural intensification. The application of agricultural herbicides and pesticides may pose a threat in run-off and groundwater contamination (D. Gower and S. Loader pers. comm. August 2012, J. Measey pers. comm. November 2012). Artisanal gold mining appears to have ceased in this area, but may have posed a threat to the species in the past (J. Measey pers. comm. November 2012). It is not known to what extent these activities may threaten this species.
It occurs in the Nilo (Gower et al. 2004) and Amani Nature Reserves and in the Mazumbai Forest Reserve, which are relatively well managed compared to other parts of Tanzania; however, there is still a need for increased protection and improved management (S. Loader pers. comm. June 2012). Further research is needed into the identity of the different subpopulations as well as into the impact of the different threat factors where it occurs.
Red List Status
Least Concern (LC)
Despite an estimated extent of occurrence (EOO) of 1,854 km2 and being considered to occur in two locations, this species is listed as Least Concern because it is locally common, tolerates habitat disturbance caused by low-intensity agriculture, and does not appear to be in decline. Should agricultural practices intensify across its range, or further research show that ongoing anthropogenic activities, inclusive of gold mining, impact the species to a greater extent than currently known, the threat category should be reassessed.
The specific status of the different populations needs assessment (S. Loader pers. comm.).
IUCN SSC Amphibian Specialist Group 2013. Boulengerula boulengeri. The IUCN Red List of Threatened Species 2013: e.T59494A16943488. http://dx.doi.org/10.2305/IUCN.UK.2013-2.RLTS.T59494A16943488.en .Downloaded on 23 February 2019