Three new species of Acanthocephala from Acanthogyrus (Acanthosentis) (Acanthocephala: Quadrigyridae) from tinfoil barb fish, Barbonymus schwanenfeldii in Lake Kenyir, Terengganu, Malaysia

This study was carried out in order to identify acanthocephalan species complexes, based on morphological variability, infecting Barbonymus schwanenfeldii from Lake Kenyir, Terengganu, Malaysia. Acanthocephala were fixed in ethanol, stained with aceto-carmine and studied morphologically by using a light microscope. Variation in morphological traits such as proboscis, proboscis receptacle, egg, testes shape and location, number of hooks and cement gland has been traditionally used to diagnose the acanthocephalans species but the delimitations between closely related species are still confusing and are always questionable among taxonomists. Molecular analysis was used for support the identification. Morphological variability prospecting reveals the presence of three different new species complexes from the subgenus Acanthosentis by referring published taxonomic keys. These new species may be distinguished from the other 46 described species of Acanthosentis by having six unique structures: the presence of an anterior parareceptacle structure (PRS); vaginal sleeve structure; a paired lateral, cone-shaped, muscular jacket surrounding the vagina; alternating pattern and size of proboscis hooks, variation in proboscis size and shape; the presence of the circular collar ring around the neck between the proboscis and trunk and lastly the presence of a muscular-like structure attached to the collar ring on the proboscis. These acanthocephalans found in the intestine of B. schwanenfeldii in Kenyir Lake Malaysia represent new species, named Acanthogyrus (Acanthosentis) kenyirensis n.sp., A. (A.) terengganuensis n.sp. and A. (A.) tembatensis n. sp

Morphological and molecular identification of Diceratocephala boschmai Baer, 1953 and Decadidymus sp. Cannon, 1991 on wild and cultured environment of Cherax quadricarinatus in Malaysia

The introduction of Australian Cherax quadricarinatus into Malaysia as an aquaculture species has resulted in wild populations in several Malaysian states, and it is now considered an invasive species. The introduction coincidentally co-introduced Diceratocephalid, flatworms that externally inhabit C. quadricarinatus. Thirty-three wild C. quadricarinatus were caught alive in Tasik Ayer Keroh, Melaka; while 32 cultured C. quadricarinatus were bought in Bandar Tenggara, Johor. Two species of ecto-symbiont (Diceratocephala boschmai and Decadidymus sp.) were morphologically identified and genetically 18S rDNA sequenced. Currently, only one 18S rDNA sequence is available for Decadidymus sp. in the GenBank, isolated from redclaw crayfish, C. quadricarinatus in Australia. This D. boschmai 18S rDNA phylogenetic analysis was consistent with the data from previous studies