Molecular and morphological characterisation of some Arabica coffee-associated parasitic nematodes in Gera and Gomma districts of southwest Ethiopia

A study of coffee rhizospheres collected from six coffee fields in the Gera and Gomma districts of Jimma Zone, southwest Ethiopia, revealed the presence of 12 genera of plant-parasitic nematodes, including Belonolaimus, Criconemoides, Cryphodera, Discocriconemella, Helicotylenchus, Longidorus, Ogma, Paratylenchus, Rotylenchus, Scutellonema, Tylenchorhynchus and Xiphinema. The genera Criconemoides, Helicotylenchus, Longidorus, Paratylenchus, Tylenchorhynchus and Xiphinema were the most prevalent, detected in all soil samples with up to 1590 individuals 100 ml-1 soil for Cryphodera. Morphological and molecular analysis of three genera with higher densities revealed a single species of an unknown Cryphodera sp., Paratylenchus leptos and Tylenchorhynchus cf. zeae occurring in all soil samples. Cryphodera is reported for the first time in Africa. Molecular analyses also revealed the presence of Xiphinema citricolum and several unknown species comprising one Discocriconemella sp., one Paratylenchus sp., four Helicotylenchus spp., two Ogma spp., one Rotylenchus sp. and three Xiphinema spp. In total, 32 partial 18S, 74 D2-D3 of 28S, three ITS sequences of ribosomal DNA and 24 partial mitochondrial COI gene sequences of 16 nematode species were generated. This study demonstrates that the identities of several potentially harmful nematodes are not well known, even in relation to highly important crops such as coffee