Novel distribution records and molecular data for species of Macrogyrodactylus Malmberg, 1957 (Monogenea: Gyrodactylidae) from Clarias gariepinus (Burchell) (Siluriformes: Clariidae) in southern Africa

Abstract

The viviparous gyrodactylid genus Macrogyrodactylus Malmberg, 1957 is endemic to Africa, composed of nine species from hosts of four freshwater fish families, including catfishes (Siluriformes: Clariidae). Three species, Macrogyrodactylus clarii Gussev, 1961; M. congolensis (Prudhoe, 1957) and M. karibae Douëllou et Chishawa, 1995, are primarily known to parasitise the African sharptooth catfish Clarias gariepinus (Burchell) in various African countries. From November 2017 to September 2019, a total of 184 individuals of C. gariepinus were collected from selected localities in southern Africa and their skin, fins and gills were surveyed for monogeneans. Three species of Macrogyrodactylus (M. clarii, M. congolensis and M. karibae) were found parasitising C. gariepinus from five localities in South Africa and Zambia. Overall prevalence was 50% to 100% with intensities of up to 109 parasites per host individual. New locality records in southern Africa, morphological observations and additional molecular data on the complete Internal Transcriber Spacer (ITS-1-5.8S-ITS-2) regions of the rDNA gene for the three gyrodactylid species are presented in this study.

First isolation and scanning electron microscopy of haptoral sclerites ofMacrogyrodactylus(Monogenea)

“…The first record of the number of spines for M. congolensis was by Prudhoe (1957) who recorded 15 small spines, followed by Douëllou & Chishawa (1995) who reported 14 small spines and Khalil & Mashego (1998) who recorded 14–15 small spines. Truter et al (2021) recorded 18–20 small spines on the male copulatory organ of M. congolensis overlapping with the measurements obtained in the present study. These discrepancies in the number of small spines in M. congolensis need further investigation as this may indicate that this trait is unreliable, or the possibility of cryptic species.…”

“…Overall haptoral sclerite morphology of M. congolensis presented in El-Naggar et al (1999), Khalil & Mashego (1998), Přikrylová & Gelnar (2008), Barson et al (2010) and Truter et al (2021) was identical to that of Macrogyrodactylus specimens from the current study (see line drawing and light micrograph in figs 1b, c and 2a–l). The haptor of M. congolensis (figs 1b, c and 2a–l, table 1) has two hamuli interconnected by a horizontal dorsal bar, a Y-shaped ventral bar consisting of two anterior lateral arms and a very short posterior central arm.…”

“…Specimens were initially observed using a Zeiss Stemi 350 stereomicroscope (Carl Zeiss, Germany), after which a Zeiss Axioplan 2 imaging light microscope with Axiovision 4.7.2 software was used to obtain photomicrographs using phase contrast. Haptoral sclerites (hamulus, dorsal bar, ventral bar, long and short rods and marginal hooks) of GAP mounted specimens were measured as per Přikrylová & Gelnar (2008) and compared to measurements for M. congolensis by Khalil & Mashego (1998), El-Naggar et al (1999), Přikrylová & Gelnar (2008), Barson et al (2010) and Truter et al (2021). Obtained photomicrographs were used to create line drawings of sclerites (shown in fig.…”

“…Obtained photomicrographs were used to create line drawings of sclerites (shown in fig. 1) using CorelDRAW (Taylor & Karney, 1990), which were then compared to available illustrations (Khalil & Mashego, 1998; El-Naggar et al , 1999; Přikrylová & Gelnar, 2008; Barson et al , 2010; Truter et al , 2021).

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“…To date, all valid species have been genetically characterized. The most common genetic markers used for DNA profiles of macrogyrodactylids are 18S and internal transcribed spacer (ITS; ITS1-5.8S-ITS2) regions of rDNA (Matejusová et al , 2003; Barson et al , 2010; Přikrylová et al , 2013; Vanhove et al , 2018; Truter et al , 2021). Macrogyrodactylus karibae is the only species with additional 28S rDNA data, while cytochrome oxidase subunit 1 (COI) mtDNA data are available for M. karibae , M. clarii and Macrogyrodactylus heterobranchii N'Douba & Lambert, 1999, as well as hybrids of the latter two species (Matejusová et al , 2003; Barson et al , 2010; Vanhove et al , 2018).…”