Abstract
M.Sc. Zoology
Only a few species of the family Diplozoidae have previously been described
from Africa, from various Labeo and Barbus species. An investigation was
undertaken respectively in the Vaal Dam and Vaal River Barrage in the
Vaal River system, South Africa to determine aspects of the morphology,
taxonomy and ecology of specimens of this family collected from the gills of
Barbus aeneus. Various fish species, namely B. aeneus, Barbus kimberleyensis,
Labeo capensis, Labeo umbratus, Cyprinus carpio, Clarias gariepinus and
Micropterus salmoides, were collected with the aid of gill nets. The fish were
killed and the length, weight and sex determined. The gills were removed from
the left and right gill chambers, placed in separate, marked petri dishes and
covered with water from the dam. Gills (from first to fourth pair) were examined
with the aid of a dissection microscope. The position of attachment and the region
on the gill namely dorsal, median or ventral, was noted. Parasites were removed,
fixed between a cover slip and glass slide in steaming hot aceto-formaldehyde
alcohol and preserved in 70 % ethanol. A morphological study was undertaken.
Results of a Scanning Electron Microscopy study illustrated the following
external characteristics namely a round opisthohaptor with four pairs of clamps,
while study of whole mounts revealed larval hooks, a round-ended intestine and
eggs without filaments. Graphic reconstruction of serial sections of the
reproductive system of parasites embedded in resin revealed that the vas deferens
of one individual opens into the common vitelline duct of the other. Parasites
were identified as belonging to the genus Paradiplozoon. The morphological
characteristics, namely the round opisthohaptor, intestine with rounded ending,
egg without filament and morphological measurements, of various structures (for
example, total body length) that differ from other species of this genus, led to the
establishment of a new species, that is, P. alwinii.