The morphology,life-cycle and systematic position of Orthetrotrema monostomum Macy & Basch, 1972, a progenetic trematode

The life-cycle of Orthetrotrema monostomum, a progenetic trematode occurring in the haemocoel of dragonfly naiads is described. The snail Thiara tuberculata acts as the intermediate host. The cercaria is xiphidiocercous, monostomate and belongs to the Microcotylous group. The course of development of the cercaria into a mature adult fluke is followed in the haemocoel of dragon-fly naiads which had been exposed to cercariae. On the basis of intraspecific variations noted in the adult flukes obtained experimentally from dragon-fly naiads, O. longicaeca Hanumantha Rao & Swamy, 1975 is synonymised with O. monostomum. Evidence is provided for the inclusion of the genus Orthetrotrema in the family Eumegacetidae. The diagnosis of the family Eumegacetidae is amended.     

On the systematic position of Ophiosacculus Macy, 1935 (digenea: Lecithodendriidae), with the erection of the Ophiosacculinae n. subfam

The phylogenetic relationships and systematic position of the digenean genus Ophiosacculus Macy, 1935 has been controversial and opinions of different authors on its systematic position and content are contradictory. Molecular analysis based on the partial sequences of the large subunit ribosomal DNA gene of the type and only valid species of the genus, Ophiosacculus mehelyi (Mödlinger, 1930), as well as previously published sequences of members of several families of Plagiorchiata (including the Allassogonoporidae, Lecithodendriidae and Pleurogenidae as potential relatives of Ophiosacculus) has shown that Ophiosacculus forms a clade with the typical representatives of the Lecithodendriidae from bats. Ophiosacculus is basal to the cluster containing Lecithodendrium, Prosthodendrium and Pycnoporus and has quite pronounced differences in the sequenced fragment compared to these genera. Based on the results of the molecular study, morphological characteristics of Ophiosacculus (in particular, possession of a seminal vesicle lying freely in parenchyma) and the fact that the type-specimen of Gyrabascus brevigastrus Macy, 1835 (type-species of the monotypic genus Gyrabascus and type-genus of the subfamily Gyrabascinae) belongs to Allassogonoporus, a new subfamily, the Ophiosacculinae, with Ophiosacculus as the type-genus, is established within the Lecithodendriidae. Molecular study did not support a close phylogenetic relationship between Allassogonoporus and Ophiosacculus, although several authors previously allocated both these genera to the Allassogonoporidae. Morphological study revealed the position of the genital pore in O. mehelyi to be at the posterior margin of the ventral sucker. An amended diagnosis of Ophiosacculus and a diagnosis of Ophiosacculinae n. subfam. are given.