The African Carnoyidae (Nematoda: Rhigonematida).: 4.: Abirovulva insolita gen. n., sp n., parasite of Coromus thomsoni (Polydesmida: Oxydesmidae) from Ivory Coast

Abirovulva gen. n. is proposed for nematode denizens of the gut of various African polydesmid diplopods (Coromus thomsoni, Oxydesmus miniodesmus parabellus, O. sicarius, O. platycercus concolor, Plagiodesmus brunneus, P variabilis and Prepodesmus ornants). The new genus is usually accompanied by species of Afrocarnoya (also apparently restricted to polydesmid diplopods) and Rhigonema and is likely to be distributed throughout the Central to West African region. Abirovulva gen. n. is unique amongst African Carnoyidae because of a combination of characters, including the very posteriorly located vulva, the unusual form of the female genital system, presence of a ventral sucker in the male, the shape of the spicules and gubernaculum and the distribution of the male copulatory papillae. Abirovulva insolita gen. n., sp. n. is proposed as the type species and is characterised by: the strongly inflated intestine just posterior to the basal bulb in both sexes, the extremely posterior vulva, both female genital tracts running anteriorly in parallel, presence of a much expanded vagina uterina acting as an egg receptacle, long and robust female tail spike; presence of a ventral sucker in the male, form of the male spicules and gubernaculum, disposition of the 15 copulatory papillae, cuticular callosities on the cloacal lips, well developed, smooth, cephalic cap in the male and the truncate male cephalic extremity. No other genus of African Carnoyidae is known to have such a posterior vulva, ventral sucker in the male or spicules and gubernaculum of such unusual form. Relationships to other genera in the Ransomnematoidea and factors that may influence niche partitioning within the host gut are discussed.