Three new Dactylogyrus species (Monogenea: Dactylogyridae) and redescription of one other, gill parasites of five Labeo spp. (Cypriniformes: Cyprinidae) from the Sanaga basin (Cameroon, Central Africa)

Imane Rahmouni,Charles Félix Bilong Bilong,Sévérin-Oscar Fankoua ,Arnold R Bitja Nyom ,Alexandre Michel Njan Nlôga,Etienne Didier Bassock Bayiha

doi:10.1590/s1984-4689.v39.e21009

Abstract

Three new and one already known species of Dactylogyrus Diesing, 1850 are described from five species of Labeo (Cyprinidae) sampled in the middle section of the Sanaga hydrosystem (Centre Region-Cameroon): Dactylogyrus sanagaensis sp. nov. from Labeo sanagaensis Tshibwabwa, 1997, L. nunensis Pellegrin, 1929, L. camerunensis Trewavas, 1974 and L. annectens Boulenger, 1903; Dactylogyrus nachtigalensis sp. nov. and D. yassensis Musilová, Řehulková & Gelnar, 2009 from Labeo batesii Boulenger, 1911; and Dactylogyrus djimensis sp. nov. from Labeo camerunensis. Dactylogyrus sanagaensis sp. nov. is close to D. longiphalloides, D. longiphallus, D. leonis, D. marocanus, and D. dembae, however it can be easily distinguished from these species by the size of MCO. Dactylogyrus nachtigalensis sp. nov. is similar to D. dembae and D. sanagaensis sp. nov. but this new species can be mainly differentiated by the length of penis. Dactylogyrus djimensis sp. nov. mostly similar to D. omega can be differentiated from it by the penis diameter. Dactylogyrus yassensis collected from Cameroon doesn’t significantly differ morphometrically from the original description, thus extends the distribution of this species to Sanaga basin. Monogenean species collected from Labeo spp. in the middle section of the Sanaga hydrosystem were classified into two morphological groups: the ‘pseudanchoratus-like group’ and the ‘cyclocirrus-like group’ newly defined herein. Phylogenetic relationships are suggested among Dactylogyrus species.

Highlights

While both Cyprinidae and Cichlidae are more represented in the African freshwater ichthyofauna (Lévêque et al 2008), cyprinids belonging to the genus Labeo Cuvier, 1816 are widely distributed throughout Africa and South-East Asia (De Weirdt et al 2007)
Members of the latter group are only represented in Lower Guinea by six valid species and an undescribed one (Tshibwabwa 1997). They are all present in Cameroon (Bitja Nyom et al 2020) that is a crossroads of many hydrographic basins (Niger, Congo, Cross and Atlantic) (Olivry 1986): Labeo sanagaensis Tshibwabwa, 1997, L. batesii Boulenger, 1911, L. nunensis Pellegrin, 1929, L. camerunensis Trewavas, 1974, L. annectens Boulenger, 1903, L. lukulae Boulenger, 1902, and Labeo sp
No record of Dactylogyrus was made from Labeo species in Cameroon because they were not investigated in this country

Summary

Introduction

While both Cyprinidae and Cichlidae are more represented in the African freshwater ichthyofauna (Lévêque et al 2008), cyprinids belonging to the genus Labeo Cuvier, 1816 are widely distributed throughout Africa and South-East Asia (De Weirdt et al 2007). About 88 species of Labeo are described in Africa, which can be divided into two distinct groups based on the presence of papillate or plicate lips. Members of the latter group are only represented in Lower Guinea by six valid species and an undescribed one (Tshibwabwa 1997). They are all present in Cameroon (Bitja Nyom et al 2020) that is a crossroads of many hydrographic basins (Niger, Congo, Cross and Atlantic) (Olivry 1986): Labeo sanagaensis Tshibwabwa, 1997, L. batesii Boulenger, 1911, L. nunensis Pellegrin, 1929, L. camerunensis Trewavas, 1974, L. annectens Boulenger, 1903, L. lukulae Boulenger, 1902, and Labeo sp. Despite the diversity of Labeo spp. in this basin, no data on their parasitic biodiversity is available

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Conclusion