Species of Ergasilus von Nordmann, 1832 (Copepoda: Ergasilidae) from cichlid fishes in Lake Tanganyika

Abstract

Ergasilus (von Nordmann, 1832) (Ergasilidae) is a species-rich group of parasitic copepods with a wide distribution in freshwater, marine and brackish environments. Up to now, 9 species of Ergasilus are known from cichlid fishes in Africa. In this study, 5 species, including 3 new, were collected from the gills of 12 cichlid species (11 genera: Bathybates, Ctenochromis, Eretmodus, Gnathochromis, Lamprologus, Neolamprologus, Ophthalmotilapia, Perissodus, Simochromis, Spathodus and Tanganicodus) of the northeastern shore of Lake Tanganyika in Burundi, namely E. macrodactylus (Sars, 1909), E. megacheir (Sars, 1909), E. caparti n. sp., E. parasarsi n. sp. and E. parvus n. sp. All species found were identified and described on the basis of adult female specimens using an integrative taxonomy approach mixing morphological characterization and molecular analyses of 2 ribosomal DNA markers (partial 18S and 28S rDNA sequences). An identification key for Ergasilus species from Lake Tanganyika is included. This study provides the first molecular data for Ergasilus species in Africa. The phylogenetic analyses suggest that the Ergasilus species parasitizing Lake Tanganyikan cichlids form a well-supported clade within the Ergasilidae. However, their phylogenetic relationships with other congeners still remain unclear due to a lack of molecular data for this diverse genus.

Keywords: Africa; Tanganyika; cichlids; diversity; parasitic crustaceans.

Graphical abstract

Fig. 1.

Map of Lake Tanganyika indicating the sampling localities along the northeastern shore in Burundi: (1) Magara; (2) Mukuruka; (3) Mvugo; (4) Nyaruhongoka.

Fig. 2.

Ergasilus macrodactylus, adult female from Gnathochromis permaxillaris. (A) Habitus, dorsal; (B) antenna, ventral; (C) mandible and maxilulle, ventral; (D) maxilla, ventral; (E) antennule, ventral; (F) abdomen and caudal rami; (G) egg sac, dorsal; (H) leg V, ventral.

Fig. 3.

Ergasilus macrodactylus, adult female from Gnathochromis permaxillaris. (A) Leg I, ventral; (B) leg II, ventral; (C) leg III, ventral; (D) leg IV, ventral.

Fig. 4.

Ergasilus megacheir, adult female from Simochromis diagramma. (A) Habitus, dorsal; (B) antenna, ventral; (C) mandible and maxilulle, ventral; (D) maxilla, ventral; (E) antennule, ventral; (F) abdomen and caudal rami; (G) egg sac, dorsal; (H) leg V, ventral.

Fig. 5.

Ergasilus megacheir, adult female from Simochromis diagramma. (A) Leg I, ventral; (B) leg II, ventral; (C) leg III, ventral; (D) leg IV, ventral.

Fig. 6.

Ergasilus caparti n. sp., adult female from Neolamprologus brichardi. (A) Habitus, dorsal; (B) antenna, ventral; (C) mandible and maxilulle, ventral; (D) maxilla, ventral; (E) antennule, ventral; (F) abdomen and caudal rami; (G) egg sac, dorsal; (H) leg V, ventral.

Fig. 7.

Ergasilus caparti n. sp., adult female from Neolamprologus brichardi. (A) Leg I, ventral; (B) leg II, ventral; (C) leg III, ventral; (D) leg IV, ventral.

Fig. 8.

Ergasilus parasarsi n. sp., adult female from Simochromis diagramma. (A) Habitus, dorsal; (B) antenna, ventral; (C) mandible and maxilulle, ventral; (D) maxilla, ventral; (E) antennule, ventral; (F) abdomen and caudal rami; (G) egg sac, dorsal; (H) leg V, ventral.

Fig. 9.

Ergasilus parasarsi n. sp., adult female from Simochromis diagramma. (A) Leg I, ventral; (B) leg II, ventral; (C) leg III, ventral; (D) leg IV, ventral.

Fig. 10.

Ergasilus parvus n. sp., adult female from Spathodus erythrodon. (A) Habitus, dorsal; (B) antenna, ventral; (C) mandible and maxilulle, ventral; (D) maxilla, ventral; (E) antennule, ventral; (F) abdomen and caudal rami; (G) egg sac, dorsal; (H) leg V, ventral.

Fig. 11.

Ergasilus parvus n. sp., adult female from Spathodus erythrodon. (A) Leg I, ventral; (B) leg II, ventral; (C) leg III, ventral; (D) leg IV, ventral.

Fig. 12.

Phylogenetic tree of Ergasilidae reconstructed by maximum likelihood. The tree is based on the combined sequences of partial genes coding 18S and 28S rRNA. Values along the branches indicate posterior probabilities from Bayesian inference and bootstrap values from maximum likelihood (dashes indicate values below 0.7 and 50, respectively). Letters (A)–(D) represent well-supported group of Ergasilidae.