Revisiting the type material of two African Diplozoinae (Diplozoidae: Monogenea), with remarks on morphology, systematics and diplozoid specificity.

The morphological characterisation of Diplozoidae spp. is highly reliant on the details of the sclerotised components of the hooks and clamps in the haptor. Only six species of (Diplozoinae) have been described from Africa, four of which have adequate morphological and even comparative ITS2 rDNA data available. However, the descriptions of (Thomas, 1957) and (Fischthal & Kuntz, 1963) lack essential taxonomic information, specifically the details for their haptoral sclerites. As such, all available material from museum collections for these two species were studied using light microscopy to supplement the original morphometric descriptions. The holotype and paratypes of were studied, but only voucher material for could be sourced. However, this voucher material for was deposited by the species authority and bore a striking resemblance to the illustrations and collection details from the original description. They were thus identified as the type series for the taxon, with a lectotype and paralectotype designated. Both and could be readily distinguished from other taxa based on the supplementary data generated here, supporting their distinctness. The haptoral sclerites of were most similar to those of Dos Santos & Avenant-Oldewage, 2016, also described from spp., while the sclerites of were most similar to Civáňová, Koyun & Koubková, 2013 and Al-Nasiri & Balbuena, 2016. Additionally, a voucher of collected from the alestid type host of was reidentified as the latter species here. This greatly simplified the known host specificity for spp. in Africa, with now exclusively reported from Cypriniformes (Cyprinidae and Danionidae), and restricted to Characiformes (Alestidae). The occurrence of all diplozoids from non-cyprinoid hosts was also investigated and several records of diplozoids occurring on non-cyprinoid hosts were collated and scrutinised. Excluding the two instances of diplozoids described and exclusively occurring on Characiformes fishes ( and (Sterba, 1957)), most other non-cyprinoid collections appear sporadic and unsubstantiated, but warrant further investigation supported by diligent taxonomic data. Even though the morphometric descriptions of both and were fully reported on here, additional material will be needed to study their genetic profiles and phylogeny.