Description of a new species from Clarias maclareni and phylogenetical analysis of Quadriacanthus (Monogenea, Dactylogyridae) species transfers between clariid and non-clariid fish hosts in Cameroon.

Recently in Cameroon, two species belonging to Quadriacanthus: Q. anaspidoglanii Akoumba, Tombi & Bilong Bilong, 2017 and Q. euzeti Nack, Pariselle & Bilong Bilong, 2016 have been recorded on gill filaments of Notoglanidium macrostoma (Siluriformes, Claroteidae) in the Memou'ou River (Nyong Basin) and Papyrocranus afer (Osteoglossiformes, Notopteridae) in Lake Ossa, respectively. These records have been considered the result of lateral transfers from Clariidae to a Claroteidae host for the first case (parasitism of N. macrostoma by Q. anaspidoglanii) and from Clariidae or Bagridae to a Notopteridae host for the second (parasitism of P. afer by Q. euzeti). In this paper, the investigation of interspecific relationships among Quadriacanthus spp. parasitizing Clariidae, Bagridae, Claroteidae and Notopteridae in Cameroon resulted in the record of Q. anaspidoglanii from N. macrostoma, Q. euzeti from P. afer, a new record of Q. levequei Birgi, 1988 from Clarias jaensis in the Nyong River, and the description of Q. barombiensis n. sp. from Clarias maclareni in Lake Barombi Mbo. The newly identified species is characterized by having an accessory piece ending in one small hook and the median expansion of its dorsal bar with two filaments. Phylogenetic analysis based on 28S rDNA sequences confirms that the Quadriacanthus spp. parasitizing gill filaments of non-clariid hosts in Cameroon originate from lateral transfers from clariid fishes, and that Clariidae are ancestral hosts of these monogenean species.

Title: Description d'une nouvelle espèce parasite de Clarias maclareni et analyse phylogénétique des transferts d'espèces de Quadriacanthus (Monogenea, Dactylogyridae) entre poissons hôtes clariidés et non clariidés au Cameroun. Abstract: Récemment au Cameroun deux espèces appartenant à Quadriacanthus : Q. anaspidoglanii Akoumba, Tombi & Bilong Bilong, 2017 et Q. euzeti Nack, Pariselle & Bilong Bilong, 2016 ont été signalées, respectivement sur les filaments branchiaux de Notoglanidium macrostoma (Siluriformes, Claroteidae), dans la rivière Memou'ou (bassin du Nyong) et Papyrocranus afer (Osteoglossiformes, Notopteridae) dans le lac Ossa. Ces signalements ont été considérés comme le résultat de transferts latéraux de Clariidae vers un hôte Claroteidae pour le premier cas (parasitisme de N. macrostoma par Q. anaspidoglanii) et d'un Clariidae ou Bagridae vers un hôte Notopteridae pour le second (parasitisme de P. afer par Q. euzeti). Dans cet article, l'étude des relations interspécifiques entre Quadriacanthus spp. parasitant des Clariidae, Bagridae, Claroteidae et Notopteridae au Cameroun a abouti au signalement de Q. anaspidoglanii chez N. macrostoma, Q. euzeti chez P. afer, un nouveau signalement de Q. levequei Birgi, 1988 chez Clarias jaensis dans le fleuve Nyong, et à la description de Q. barombiensis n. sp. chez Clarias maclareni dans le lac Barombi Mbo. L'espèce nouvellement identifiée se caractérise par la présence d'une pièce accessoire se terminant par un petit crochet et l'expansion médiane de sa barre dorsale avec deux filaments. L'analyse phylogénétique basée sur les séquences d'ADNr 28S confirme que les Quadriacanthus spp. des filaments branchiaux parasitant des hôtes non-clariidés au Cameroun proviennent de transferts latéraux de poissons clariidés, et que les Clariidae sont bien les hôtes ancestraux de ces espèces de monogènes.

Influence of preservative and mounting media on the size and shape of monogenean sclerites.

Based on Cichlidogyrus sp. (Monogenea, Ancyrocephalidae) specimens from Hemichromis sp. hosts, we tested the influence of different methods to fix/preserve samples/specimens [frozen material, alcohol or formalin preserved, museum process for fish preservation (fixed in formalin and preserved in alcohol)] and different media used to mount the slides [tap water, glycerin ammonium picrate (GAP), Hoyer's one (HM)] on the size/shape of sclerotized parts of monogenean specimens. The results show that the use of HM significantly increases the size of haptoral sclerites [marginal hooks I, II, IV, V, and VI; dorsal bar length, width, distance between auricles and auricle length, ventral bar length and width], and changes their shape [angle opening between shaft and guard (outer and inner roots) in both ventral and dorsal anchors, ventral bar much wider, dorsal one less curved]. This influence seems to be reduced when specimens/samples are fixed in formalin. The systematics of Monogenea being based on the size and shape of their sclerotized parts, to prevent misidentifications or description of invalid new species, we recommend the use of GAP as mounting medium; Hoyer's one should be restricted to monogenean specimens fixed for a long time which are more shrunken.