Two species of Spinitectus Fourment, 1884 have been recorded from southern Africa, namely Spinitectus polli Campana-Rouget, 1961 and Spinitectus petterae Boomker, 1993, both from the Limpopo River system. Spinitectus petterae was described from North African catfish, Clarias gariepinus (Burchell), whereas S. polli infects squeakers, Synodontis spp. During parasitological surveys in the Vaal River system (Orange River catchment), Spinitectus specimens were collected from C. gariepinus. These systems are adjacent but not connected. Therefore, this study aimed to identify the specimens collected using morphological and molecular techniques. The morphological study included light and scanning electron microscopy of whole specimens and excised spicules. Specimens were genetically characterised using 18S rDNA, 28S rDNA and cox1 mtDNA. Additionally, immature specimens of S. petterae were collected near the type locality. Morphological characteristics were most similar to S. petterae from C. gariepinus, whereas genetic data were dissimilar to all available data for the genus. Additional morphological characteristics noted for S. petterae in the present study were the details of the left and right spicule structure and the porous structures on the pseudolabia. Specimens from the Vaal River system differed from those originally described as S. petterae by additional spines posterior to the third ring, lacking caudal alae and variable total body and male oesophagus length. Based on 18S rDNA, haplotypes from the type locality varied only slightly from the study material, supporting the morphological identification. However, 28S rDNA and, more conspicuously, cox1 mtDNA displayed substantial variation between specimens from these localities, which needs further investigation. Haplotypes generated in the present study were highly dissimilar to those characterised for S. petterae from Tanzania and Egypt. Nevertheless, the nematodes collected from C. gariepinus in the Vaal River system are considered S. petterae. This study expands the geographical distribution and adds additional morphological and genetic information for S. petterae, contributing to the limited knowledge of African species of Spinitectus.

Spinitectus spp. (Rhabdochonidae) are enteric nematodes characterized by annular spines. At the anterior end, these spines assist attachment and aid penetration into the host tissue. During parasitological surveys of the Vaal River system from three localities, below the Vaal River Barrage in the Vaal Dam surrounding UJ island and below the Grootdraai Dam, Spinitectus specimens were collected from the stomach lining of the sharptooth catfish, Clarias gariepinus (Burchell, 1822). Histopathological effects induced by Spinitectus petterae Boomker, 1993 on C. gariepinus has not been studied.Thus, the aim of this study was to describe the histopathology induced by S. petterae.For light microscopic examination, tissue samples with attached S. petterae were sectioned and stained with haematoxylin and eosin. Additionally, attached nematodes were also studied using scanning electron microscopy. Leukocytes were counted with the Disector principle. Standard infection parameters (prevalence, mean intensity and abundance) were calculated and compared to host parameters. Prevalence varied greatly (11.77% to 100%) between localities. Histopathology induced by S. petterae to C. gariepinus stomach (cardiac region) consisted of significant leukocyte infiltration, acute ulcerations and chronic granuloma formation. This was similar to the pathology of other Spinitectus occurring in host anterior intestine and stomach, but granuloma formation had not been previously reported and this suggests chronic infection in wild caught fish.

Spinitectus is ’n genus van parasitiese nematode wat aan die familie Rhabdochonidae behoort, wat gekenmerk word deur die teenwoordigheid van ringe skerp stekels wat posteriorwaarts in grootte verklein. Tydens standaard parasitologiese ondersoeke in die Vaaldam, Suid-Afrika (Maart 2018), is agt Spinitectus-wurms ingesamel van Clarias gariepinus. Slegs twee spesies is in Suid-Afrika bekend en albei is in die Kruger Nasionale Park ingesamel: Spinitectus petterae (Krokodilrivier) van C. gariepinus en Spinitectus polli (Sabierivier) van Synodontis zambezensis. Die genus is nog nie tevore in die Vaalrivier aangeteken nie. Die doel van hierdie studie is om die morfologie, morfometrie en molekulêre kenmerke van die wurms wat in die Vaalrivier ingesamel is met die ander Afrika-spesies te vergelyk en hulle identiteit te bepaal. Met behulp van ligmikroskopie is die wurms met anhidriese gliserol opgehelder, bestudeer en daarna met ander Afrika-spesies vergelyk. Verskille tussen die skerp stekels en lengteverhoudings van strukture is vir die vergelykings gebruik. Een wurm is met behulp van skandeerelektronmikroskopie met heksametieldisilasaan (HMDS) gedroog om sy eksterne morfologie te bestudeer. Onderskeidende strukture wat opgemerk is, was die kefaliese en kaudale papille, die vorm van die pseudolabia en die plasing van die stekelringe. Die klein ribosomale subeenheid (18S) van rDNS is gebruik om die identiteit van die wurms te bepaal. Die ingesamelde spesie was geneties die naaste verwant aan S. petterae, maar die assosiasie is swak ondersteun en hulle kon geneties onderskei word. Uitsteeksels teenwoordig op die wyfies was soortgelyk aan S. polli en S. petterae. Die lengtes van die wurm voor die vulva teenoor die lengte na die anus was soortgelyk aan Spinitectus maleficius, Spinitectus allaeri en S. petterae. Die spikulum-grootte was soortgelyk aan S. petterae, S. polli en Spinitectus minusculus. Weens ’n beperkte verband tussen die genetiese en morfologiese resultate van die ingesamelde wurms van die Vaaldam en Spinitectus-spesies wat in ander gebiede in Afrika ingesamel is, is meer inligting derhalwe nodig om hierdie nematode akkuraat te identifiseer of moontlik as ’n nuwe spesie te beskryf.