Digenetic trematodes infecting anurans from a derived savanna biotope in Edo State, Nigeria

Abstract

An investigation of the digenetic trematodes of anurans from Agbede, a location in the derived savanna biotope in Edo state,
Nigeria was conducted from August, 2007 to July, 2008. Anuran hosts examined included Sclerophrys maculata, S.
regularis, Ptychadena pumilio, P. bibroni, P. oxyrhynchus, Hoplobatrachus occipitalis and Hylarana galamensis. The
anurans were collected using the Visual Acoustic Encounter Survey (VAES) method, dissected and examined for trematode
infections. A total of 267 anurans were examined of which 33 were infected with an overall prevalence of 12.36%. Seasonal
prevalence was 14.88% for the wet season and 8.08% for dry season. The difference in prevalence values was not statistically
significant (p >0.05). Four digenetic trematodes, namely, Mesocoelium monodi, an unidentified Mesocoelium sp.,
Haematoloechus exoterorchis and an unidentified Haematoloechus sp. Haematoloechus exoterorchis was recovered from H.
occipitalis while the unidentified Haematoloechus sp. infected H. occipitalis and Sclerophrys maculata. Mesocoelium
monodi infected only Sclerophrys maculata while the unidentified Mesocoelium sp. was a generalist, infecting five anuran
hosts. Sclerophrys maculata is thus a new host record for the genus Haematoloechus in Nigeria. In conclusion, this study
revealed a low trematode diversity in the anurans of the savanna-mosaic at Agbede. However, anurans from this location
harboured two new trematodes: an unidentified Mesocoelium sp and a Haematolechus sp. Sclerophrys maculata as a new
host record for the genus Haematoloechus in Nigeria. More specimens of the Haematoloechus sp. are needed for the
morphological description and molecular characterization of the parasite, to establish its relationship with the cogener in
H.occipitalis.

Keywords: Derived savannah, Anurans, Digenetic trematodes, new host record