The holotype was collected in 1987 at 2,000 m asl from the Cyamudongo Forest in Cyangugu Prefecture, Rwanda, which is a relict of the larger Nyungwe Forest about 20 km to the northeast (Nussbaum and Hinkel 1994). Further fieldwork in 2006 and 2009 recorded the species at three sites in the same region inside and on the edge of Cyamudongo Forest (1,743-1,839 m asl) (Gower et al. 2011; Measey et al. 2011). In 2009, a few days of fieldwork at four sites with limited digging in the nearby Nyungwe Forest did not record the species (Gower et al. 2011). There is an unsubstantiated report of a caecilian near Gisakura within the Nyungwe Forest; it is cited in Behangana et al. 2009 Biod. Cons., but there is no voucher specimen or photograph to verify this (T. Doherty-Bone pers. comm. December 2015). There has been little caecilian fieldwork beyond the type locality, so the species might occur more widely. However, pending confirmation elsewhere, it has been mapped to the approximate boundaries of Cyamudongo Forest and its extent of occurrence (EOO) is 7 km2.
Habitat and Ecology
This soil-dwelling species is found in primary montane forest habitat. It also occurs into small-holder farmland (maize and banana plantations; D. Gower pers. comm. August 2012 and Measey et al. 2011) adjacent to the forest - a pattern consistent with other African caecilians indicating that it tolerates a degree of disturbance. On the assumption that its breeding biology is similar to that of other species of Boulengerula, it is oviparous with direct development.
The species is locally abundant: it seems to be abundant at Cyamudongo village and its surrounding farmland; however, in comparison, it is less abundant in Cyanmudongo forest (T. Doherty-Bone and F. Pupin pers. comm. August 2012) but this may be because it is easier to dig pit traps in farmland. Its population trend remains unknown.
Cyamudongo is surrounded with industrialized tea plantation on one side and subsistence farming on the other (T. Doherty-Bone pers. comm. December 2015). Threats to caecilians are poorly understood, but assuming that soil moisture and temperature maintained by vegetation is important for the species, possible threats include habitat disturbance and conversion caused by deforestation and agricultural intensification (including the application of agricultural herbicides and pesticides) (D. Gower and S. Loader pers. comm. December 2015).
It occurs in Cyamudongo Forest, which has been annexed to Nyungwe National Park. Some development is taking place for wildlife tourism as chimpanzees occur in the forest.
Habitat protection of the Cyamudongo forest fragment is required.
Understanding the species distribution is a research priority with additional caecilian surveys in Nyungwe National Park, the adjoining Kibira National Park in Burundi and other forested mountains around Rwanda and Uganda (T. Doherty-Bone pers. comm. December 2015). Further information is also needed on this species' taxonomy, population status, and natural history..
Red List Status
Listed as Vulnerable because it seems to be restricted to the vicinity and elevation of Cyamudongo Forest where small-holder agriculture and small-scale wood extraction poses a moderate threat. African caecilians are often found in farmland outside forested areas, but seem to become less abundant when agriculture is intensified to cash crops such as coffee or tea. Therefore higher levels of wood extraction and deforestation or agricultural intensification constitute plausible future threats that would rapidly affect this species causing it to becomes Critically Endangered.
IUCN SSC Amphibian Specialist Group 2016. Boulengerula fischeri. The IUCN Red List of Threatened Species 2016: e.T59497A13323620. http://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T59497A13323620.en .Downloaded on 18 January 2019