Macrogyrodactylus congolensis ( Prudhoe, 1957 ) Yamaguti, 1963

Truter, Marliese, Acosta, Aline A., Weyl, Olaf L. F. & Smit, and Nico J., 2021, Novel distribution records and molecular data for species of Macrogyrodactylus Malmberg, 1957 (Monogenea: Gyrodactylidae) from Clarias gariepinus (Burchell) (Siluriformes: Clariidae) in southern Africa, Folia Parasitologica (027) 68, pp. 1-14 : 7-8

Macrogyrodactylus congolensis ( Prudhoe, 1957) Yamaguti, 1963 Figs. 2D–F , 3B,D (ii); Table 5

S y n o n y m: Neogyrodactylus congolensis Prudhoe, 1957

T y p e h o s t: Clarias gariepinus (Burchell) ( Siluriformes : Clariidae ).

T y p e l o c a l i t y: Lake Upemba (Lualaba River), Democratic Republic of the Congo.

O t h e r r e c o r d s: Clarias gariepinus : Egypt – El-Naggar et al. (1999, 2001a,b, 2004b, 2007, 2017, 2019), Hagras et al. (1999), Arafa (2000, 2011), Arafa et al. (2003, 2013, 2014), Mashalay et al. (2019); Democratic Republic of the Congo – Prudhoe (1957), Vanhove et al. (2018); Kenya – Barson et al. (2010); South Africa – Khalil and Mashego (1998), Madanire-Moyo et al. (2010, 2012); Uganda – Thurston (1970), Akoll et al. (2012). Clarias anguillaris : Senegal – Přikrylová and Gelnar (2008), Barson et al. (2010).

L o c a l i t i e s (p r e s e n t s t u d y): South Africa: Vaal River, North West Province and Usuthu River, Ndumo Game Reserve ( NGR), KwaZulu-Natal Province ; Zambia: Barotse floodplain, Zambezi River , Northwestern Province , Kabompo River , Northern Province .

S i t e o f i n f e s t a t i o n: Skin and gills.

Vo u c h e r m a t e r i a l: Nineteen voucher specimens deposited in, NMB P 812–817, 823.

R e p r e s e n t a t i v e D N A s e q u e n c e: 696 bp long sequence of the ITS1-5.8S-ITS2 region of the rRNA gene of one isolate. GenBank accession number: MZ869848 . Hologenophore, NMB P 828.

S p e c i m e n s s t u d i e d: n = 25 (Vaal River, SA), n = 2 (Usuthu River, SA), n = 1 (Barotse floodplain, ZM), n = 1 (Kabompo River, ZM) .

I n f e c t i o n r a t e: Usuthu River ( SA): P = 3%, IF = 1; Vaal River ( SA): P = 33%, IF = 1–109; Barotse floodplain (ZM): P = 6%, IF = 1; Kabompo River (ZM): P = 50%, IF = 1 .

Morphological observations (measurements provided in Table 5 ): Morphology of haptoral sclerites similar to illustrations provided in description of Prudhoe (1957). Hamulus complex of M. congolensis large in size, has slender hamuli less sharply curved into point and root, armed with 16 marginal hooks. Marginal hook sickle robust, with noticeable curvature in base near anterior end of sickle. Anterior end of sickle base rounded and convex, with indentation on distal side as it joins sickle blade that is short, curved inward tapering into a fine point and stops before the proximal end of sickle base ( Figs. 2E , 3D (ii)). Hamuli complex has small uniform dorsal bar, wider than long, Y-shaped ventral bar with long anterolateral processes, and short posterior central arm. Two narrow rod-like sclerites accompany ventral bar ( Figs. 2D–F , 3B ). Cirrus observed in one specimen from the Usuthu River (SA) and Barotse floodplain (ZM), respectively, and 17 individuals from the Vaal River (SA), each armed with 18–20 small spines and one large spine ( Fig. 2F ).

Remarks. The dimensions of the hamulus (total length and the length of the shaft, root and point) from specimens studied from the Vaal and Usuthu rivers (SA) and the Kabompo River and Barotse floodplain (ZM) are similar in size to specimens from the Middle Letaba Dam and Lake Turkana in Kenya ( Khalil and Mashego 1998, Barson et al. 2010). Macrogyrodactylus congolensis specimens from Senegal seems to have smaller hamuli compared to the present and other studies (see Přikrylová and Gelnar 2008). Dimensions obtained for the undivided dorsal bar in the present study do not deviate from the ranges found in other studies. Marginal hook measurements are also in accordance with previously recorded measurements (see Table 5 ). The morphology of the marginal hook sickle conforms to those illustrated for M. congolensis from Kenya (see Barson et al. 2010). Prudhoe (1957) reported fewer cirrus spines (15), with one large spine in his description of M. congolensis . Details on the morphology of the marginal hooks were not provided in the description of Prudhoe (1957), which are added in the present study. Comparative measurements are presented in Table 5 .

Figures

Fig. 2. Micrographs showing the morphological features of Macrogyrodactylus clarii Gussev, 1961 (A–C), M. congolensis (Prudhoe, 1957) (D–F), and M. karibae Douëllou et Chishawa, 1995 (G, H). A, D, G – hamuli complex; B, E, H – sickle of marginal hook; C, F, I – cirrus with spines.

Fig. 3. Illustrations of the hamuli of Macrogyrodactylus clarii Gussev, 1961 (A); M. congolensis (Prudhoe, 1957) (B); M. karibae Douëllou et Chishawa, 1995 (C). D – sickle of marginal hooks of M. clarii (i), M. congolensis (ii), and M. karibae (iii). Abbreviations: Ham – hamuli, Vbar – ventral bar, Dbar – dorsal bar, R1 and R2 – ventral bar rod-like sclerites.