Morphological study of Lappetascaris lutjani Rasheed, 1965 (Nematoda: Ascaridoidea) from a new host, Ilisha compressa Randall (Clupeiformes: Pristigasteridae), in the Persian Gulf off Iraq.

The genus Lappetascaris is a poorly known ascaridoid group. In the present study, the detailed morphology of the type species of Lappetascaris, L. lutjani, was further studied using light and scanning electron microscopy, based on the newly collected specimens from a new host Ilisha compressa Randall (Clupeiformes: Pristigasteridae) in the Persian Gulf off Iraq. Some previously unreported morphological features of taxonomic significance were observed, including the vulva with swollen lips, the egg with thick shell, the precloacal papillae being 10-14 pairs and the large mastoid phasmids in the female. A broad range of morphometric variability in the lengths of body, oesophagus, intestinal caecum and spicules was found among different individuals from different fish hosts and localities. Moreover, the validity of L. chandipurensis Gupta & Masoodi, 1990 and L. suraiyae Kalyankar, 1975 was discussed, which should be considered as synonyms of L. lutjani. Lappetascaris lutjani was reported from the Iraq waters for the first time.