Epsilonematidae (Nematoda: Desmodoroidea) From the East African Coast, With a Discussion On the External Morphology of Cuticular Appendages

Abstract

Morphological features of the cuticular appendages, such as spines, thorns, setae and flaps are described on the basis of SEM pictures of three new and three known species of the Epsilonematidae from East African coasts. Epsilonema espeeli sp.n. is characterized by the presence of six subcephalic setae and a large number of hair-like spines on the dorsal body side; males are characterized by three pairs of copulatory thorns, three precloacal thorns and an anal tube; females have a large citucular flap covering the vulva. Metepsilonema iuvenisspinosum sp.n. is characterized by its small size, ornamentation and shape of the body annules, conspicuous inversions in direction of the body annules (3 dorsal inversions and 1 ventral inversion), oval amphid, 4 pairs of supporting setae of which the third pair is the longest one in the males and the last pair the longest one in the female, length of the spicules and the subdorsal spines on the female (and juveniles) tail. Perepsilonema ritae sp.n. is characterised by sexual dimorphism in: amphidial shape (slit-like in the males, spiral in the females), number of subcephalic setae (8 in the males, 6 in the females), ornamentation of the body annules, sudden broadening of the body just behind the ventral body curvature and a slender annule posterior to the ventral body curvature. Males have large copulatory thorns and slender spicules. Additional morphological information on Epsilonema parvospina Decraemer, 1982, Metepsilonema bermudae Lorenzen, 1973 and Perepsilonema kellyae Gourbault & Decraemer, 1988 is presented and important external characteristics are illustrated with SEM pictures. The external morphology of the ambulatory setae is compared between specimens of the Epsilonematidae and one species of Draconematidae (Dracograllus eira (Inglis, 1968)).