The status of the nominal species of Haploporus Looss, 1902 and Lecithobotrys Looss, 1902 is re-assessed by means of a comparative morphological study based on newly collected specimens from the western Mediterranean, the re-examination of museum material and a critical evaluation of published data. H. benedeni (Stossich, 1887) (type-species) is described and H. lateralis Looss, 1902 is considered to be its junior synonym. Additional data are given for H. pseudoindicus Rekharani & Madhavi, 1985, H. spinosus Machida, 1996 and H. magnisaccus Machida, 1996. Species parasitising Valamugil spp. from the Indo-West Pacific region, H. indicus Rekharani & Madhavi, 1985, H. spinosus, H. magnisaccus, H. mugilis Liu & Yang, 2002 and H. muscolosaccus Machida, 2003, are considered incertae sedis with respect to their generic affiliation. H. pacificus (Manter, 1963) (syn. Neohaploporus pacificus Manter, 1963), H. pseudoindicus and H. musculosaccus are designated as species inquirendae and H. lossii Al-Bassel, 1990 is considered to be a nomen nudum. Lecithobotrys putrescens Looss, 1902 is described based on newly collected material from Liza spp. Pseudolecithobotrys n. g. is erected to accommodate Lecithobotrys stomachicola Machida, 1996, as P. stomachicola (Machida, 1996) n. comb., from the North Pacific. L. aegyptiacus Hassan, El-Aziz, Khidr & Abu Samak, 1990 is considered to be a synonym of Saccocoelium tensum Looss, 1902, and L. brisbanensis (Martin, 1974) (syn. Paralecithobotrys brisbanensis Martin, 1974), L. vitellosus Sharma & Gupta, 1970 and L. suezcanali Nisreen Ezz El-Dien, Abdel-Rahman, El-Gawady, Imam & Fahmy, 1990 are regarded as species inquirendae. New generic diagnoses are presented for both Haploporus and Lecithobotrys.