Four new species of Schilbetrema (Monogenea: Dactylogyridae) from Schilbe spp. (Siluriformes: Schilbeidae) in the Sanaga River (Sanaga Basin) and Boumba River (Congo Basin) in Cameroon

ABSTRACT Monogeneans are among the main parasites affecting aquaculture worldwide. The present study describes four new species belonging to Schilbetrema, which is only known from African catfishes. Host specimens were sampled from the Sanaga Basin and from the Boumba River (Congo Basin) using gill nets or purchased at local fish markets. Four new species, namely Schilbetrema bilongi sp. nov., Schilbetrema sanagaensis sp. nov., Schilbetrema ducentesimum sp. nov. from Schilbe mystus (Linnaeus, 1758) and Schilbetrema asambaensis sp. nov. from Schilbe intermedius Rüppel, 1832 are described. Schilbetrema bilongi sp. nov. is close to S. spirocirra in the morphology of the dorsal anchors; it differs in the morphology of the dorsal bar, distal part of the accessory piece, dorsal anchor length and number of turns of the male copulatory organ (MCO). Schilbetrema ducentesimum sp. nov. is close to S. hexacornis in the morphology of the ventral anchors, ventral bar and MCO; it differs in the morphology of the dorsal bar, length of the dorsal anchor, MCO and presence of to two light sclerotised parts. Schilbetrema sanagaensis sp. nov. is close to S. ducentesimum sp. nov. in the morphology of the dorsal bar and ventral anchors; it differs from this species by the morphology of the dorsal anchors, the distal extremity of the accessory piece, MCO length and the length of the dorsal anchors. Schilbetrema asambaensis sp. nov. resembles S. eutropii and S. calamocleithrum. It differs from S. calamocleithrum by the morphology of the accessory piece, the ventral bar, MCO length; and from S. eutropii by the morphology of the ventral bar and MCO length.