Coptodon, Gervais, 1853

Jorissen, Michiel W. P., Pariselle, Antoine, Huyse, Tine, Vreven, Emmanuel J., Snoeks, Jos, Decru, Eva, Kusters, Thomas, Lunkayilakio, Soleil Wamuini, Bukinga, Fidel Muterezi, Artois, Tom & Vanhove, Maarten P. M., 2018, Six new dactylogyrid species (Platyhelminthes, Monogenea) from the gills of cichlids (Teleostei, Cichliformes) from the Lower Congo Basin, Parasite (Paris, France) 25 (64), pp. 1-21 : 17

Parasites of Coptodon

From the Tondé estuary (see Fig. 1 ), the non-native Coptodon rendalli was captured [10]. Its native range includes tributaries and parts of the Middle and Upper Congo, the Zambezi, Cuanza, Catumbela, Okavango and Cunene rivers [10]. In Lower Congo, Coptodon rendalli was infected by Cichlidogyrus berradae Pariselle & Euzet, 2003 ; Cichlidogyrus cubitus Dossou, 1982 and Cichlidogyrus flexicolpos Pariselle & Euzet, 1995 (see Table 1 ). These species have not been found on Coptodon rendalli before, but on other representatives of Coptodon from Benin, Ivory Coast, Cabinda and the ROC [35]. Additionally, parasite species known from Coptodon rendalli from other regions, such as Cichlidogyrus dossoui Douëllou, 1993 ; Cichlidogyrus quaestio Douëllou, 1993 ; Cichlidogyrus papernastrema Price, Peebles & Bamford, 1969 or Cichlidogyrus tiberianus Paperna, 1960 [7, 14, 46] were not found in Lower Congo. This indicates that Coptodon rendalli lost its original parasite fauna during or after introduction, supporting the enemy-release hypothesis [38]. When comparing the parasite fauna of the native Coptodon tholloni with that of Coptodon rendalli in this study, only C. cubitus is shared between the two hosts. However, our sample size is small and, therefore, it is presumable that more parasite species are shared. Cichlidogyrus cubitus does not occur in the native range of Coptodon rendalli , so it is possible that Coptodon rendalli acquired this parasite through a spillback effect from Coptodon tholloni [11]. The same applies for C. flexicolpos on Coptodon rendalli . However, the reservoir for C. flexicolpos in Lower Congo could also be Coptodon guineensis , since there are no records of C. flexicolpos on Coptodon tholloni . Furthermore, Coptodon guineensis is known to host C. flexicolpos [29] and to occur in the mangroves of Lower Congo [10]. In our study, Gyrodactylus chitandiri Zahradníčková, Barson, Luus-Powell and Přikrylová, 2016 infected Coptodon tholloni , which constitutes a new host and geographical record and results in a disjunct distribution for G. chitandiri . The parasite is known from Coptodon rendalli and Pseudocrenilabrus philander (Weber, 1897) from Chirundu, Zambezi River and Lake Kariba [49], whilst it was lacking in Upper Congo on both hosts [14]. Instead, Coptodon rendalli was infected by Gyrodactylus nyanzae Paperna, 1973 in Upper Congo [14]. The disjunct distribution of G. chitandiri could be biased due to limited sampling in the past. From our observations, species of Gyrodactylus are far less prevalent (occurring on one out of 14 infected cichlid specimens in Lower Congo and on 1 out of 12 in Upper Congo) than species of Cichlidogyrus on gills of African cichlids, so it is easy to miss species of Gyrodactylus during sampling. We hypothesize that G. chitandiri shows a continuous distribution from the Zambezi Basin to Lower Congo. It should be noted that although their minimum prevalence is lower than that of species of Cichlidogyrus , their infection intensity is often higher (see Table 2 in this study and [14]). One specimen of Coptodon tholloni from the Ndimba Leta ponds, Mbanza-Ngungu (locality 3, Fig. 1 ) was exclusively infected by Cichlidogyrus tilapiae Paperna, 1960 . This parasite is a generalist (see [21]), but has mostly been found on mouth-brooding cichlids (Oreochromini, see [8]) and has a wide native range that spans most of Central and western Africa, and the Levant [14, 27, 35]. Several species of Coptodon have been screened previously for parasites (e.g. Coptodon rendalli from Upper Congo [14, 46]), but of these, C. tilapiae has only been found on Coptodon zillii , so far [9]. In the case of the C. tilapiae infection on Coptodon zillii , O. niloticus was also present in the area [9], which is also the case in the Ndimba-Leta ponds. Whether the infection of C. tilapiae on Coptodon tholloni is natural or a result of spillover (see [45] and references therein) has to be determined in future research. If the infection is the result of spillover, this would support the hypothesis of Jorissen et al. [14], that certain aquatic systems, such as ponds or artificial lakes, stimulate interspecies interactions between cichlid hosts and have a higher host density, both of which stimulate parasite hostswitching.

Figures

Figure 1. Overview of sampling localities (red dots) with the ecoregions in italics. Localities 3 and 5 are located within the cities Mbanza- Ngungu and Kisantu, respectively. The inset shows the Lower Congo region on the African continent. Sampling localities: 1, Tondé Estuary near Muanda (05°57035.900S 12°21058.400E); 2, Muila Kaku, mangroves near Lower Congo River (05°5903300S 12°35003.200E); 3, Ndimba Leta ponds, Mbanza-Ngungu, in between the Lunzadi and Lukasi rivers of which the latter flows into the Kwilu and Likunga (05°1501000S 14°5102400E); 4, Pond near Kila Kindinga and Lukasi river (5°290700S 14°530400E); 5, Inkisi River, off the Jardin botanique de Kisantu (05°0800200S 15°0305200E); 6, Mvuazi River, Inkisi (5°190S 15°70E); 7, Mbola River near Tshianya village (05°52009.800S 12°39052.600E); 8, Congo River near Nganda Flash station (06°02001.800S 12°31048.200E), 9, Muila Nzenze, Kibamba village, mangroves near Congo River (06°00006.800 S 12°4002700 E). Rivers in blue.