Annulotrema (Monogenea: Dactylogyridae) from the gills of African tetras (Characiformes: Alestidae) in Lake Turkana, Kenya, with descriptions of four new species and a redescription of A. elongata Paperna and Thurston, 1969

Two New Species of Annulotrema (Monogenea: Dactylogyridae) Gill Parasites of Brycinus macrolepidotus Valenciennes, 1849 from Nyong River, Cameroon

PURPOSE

Research on gill monogeneans of Characiform has made it possible to find two new species belonging to the genus Annulotrema. The purpose of this paper is to carry out their morphological description.

METHODS

Specimens of Brycinus macrolepidotus were captured in the Nyong River at Akonolinga. Each monogenean was mounted between slide and cover slip in a drop of glycerin ammonium picrate mixture. The sclerotized parts of their haptor and reproductive organs were then drawn and measured.

RESULTS

Two new species of Annulotrema were described. Annulotrema ngombiensis n. sp. is morphologically close to Annulotrema tenuicirra Paperna, 1973 and Annulotrema pikei Price, Peebles and Bamford, 1969. However, the new species differs from these other two mainly by the characteristic well-marked terminal cap and the tubiform prostatic reservoir of the accessory part of its MCO, as well as by its dorsal bar with a characteristic triangular piece in the middle of the fork and its ventral bar without filaments. Annulotrema nkengfacki n. sp. is distinguished from all other species previously described as well as from its closest congeners, Annulotrema helicocirra Paperna, 1973 and Annulotrema bouixi Birgi, 1988 by the structure of its MCO whose accessory part is composed of a trapezoid structure surmounted by another which is forked-shaped and by its arched-shaped ventral bar with an inner lining.

CONCLUSION

Brycinus macrolepidotus from Cameroon can harbour two species of Annulotrema, both described in the current study. This result contributes to the knowledge of the species diversity of this genus in the Nyong Basin.

Species of Characidotrema Paperna & Thurston, 1968 (Monogenea: Dactylogyridae) from fishes of the Alestidae (Characiformes) in Africa: new species, host-parasite associations and first insights into the phylogeny of the genus

Background

African tetras (Alestidae) belonging to Brycinus Valenciennes are known to be parasitized with monogeneans attributed to two genera, Annulotrema Paperna & Thurston, 1969 and Characidotrema Paperna & Thurston, 1968 (Dactylogyridae). During a survey of monogeneans parasitizing alestids, species of Characidotrema were collected in Cameroon, D. R. Congo, Senegal, South Africa, Sudan and Zimbabwe. This paper provides new morphological data and the first molecular analysis broadening our knowledge on the diversity of these parasites.

Results

Seven species (four known and three new) of Characidotrema are reported from two species of Brycinus: C. auritum n. sp. and C. vespertilio n. sp. from B. imberi (Peters); and C. brevipenis Paperna, 1969, C. nursei Ergens, 1973, C. pollex n. sp., C. spinivaginus (Paperna, 1973) and C. zelotes Kritsky, Kulo & Boeger, 1987 from B. nurse (Rüppell). Species identification was based on morphological analysis of the sclerotized structures supported by nuclear ribosomal DNA (partial 18S rDNA, ITS1, and 28S rDNA) sequence data. Morphological analysis confirmed that the most apparent character distinguishing species in the genus is the morphology of the male copulatory organ and vagina. Observations on the haptoral sclerotized elements of these parasites by means of phase contrast microscopy revealed the presence of a sheath-like structure relating to the ventral anchor, a feature that supplements the generic diagnosis of Characidotrema. Maximum Likelihood and Bayesian analyses of the large subunit (28S) rDNA sequences recovered Characidotrema species isolated from the two Brycinus hosts as monophyletic, and indicated a closer relationship of this group to monogeneans parasitizing African cyprinids (Dactylogyrus spp.) and cichlids (species of Cichlidogyrus Paperna, 1960, Scutogyrus Pariselle & Euzet, 1995, and Onchobdella Paperna, 1968) than to those from catfishes (species of Quadriacanthus Paperna, 1961, Schilbetrema Paperna & Thurston, 1968 and Synodontella Dossou & Euzet, 1993). The overall agreement between the morphological diversification of the MCOs and the molecular tree observed in this study indicates that significant phylogenetic signals for clarifying relationships among species of Characidotrema are present in the characteristics of the MCO.

Conclusions

It seems that intra-host speciation is an important force shaping the present distribution and diversity of Characidotrema but further studies are necessary to confirm this hypothesis and assess questions related to the phylogeny of these parasites. To identify potential co-speciation events, co-phylogenetic analyses of these monogeneans and their alestid hosts are required.

Two new species of Annulotrema (Monogenea: Dactylogyridae) from Hydrocynus vittatus (Characiformes: Alestidae) in Lake Kariba, Zimbabwe

Two new and one known species of Annulotrema Paperna & Thurston, 1969 are reported from the gills of the tigerfish Hydrocynus vittatus Castelnau, 1861, collected in Lake Kariba, Zimbabwe. The new species, Annulotrema pseudonili n. sp. and A. bracteatum n. sp., are described and distinguished mainly on the basis of features of the male copulatory organ (MCO). Annulotrema pseudonili n. sp. most closely resembles A. nili Paperna, 1973, but differs from it by possessing a more delicate MCO with a thin-walled base without a fibrous distal part. Annulotrema bracteatum n. sp. is most similar to Annulotrema ruahae Paperna, 1973, from which it differs by having an MCO composed of a longer copulatory tube and a leaf-shaped accessory piece enveloping the distal part of the tube. The presence of Annulotrema pikoides Guégan, Lambert & Birgi, 1988 on H. vittatus in Zimbabwe represents a new locality record for this parasite.