Displaying all 6 publications

  1. Tan WB, Lim LH
    Folia Parasitol., 2009 Sep;56(3):180-4.
    PMID: 19827361
    One new and three previously described species of Trianchoratus Price et Berry, 1966 were collected from the gills of Channa lucius (Cuvier) and Channa striata (Bloch) from the Bukit Merah Reservoir, Perak and Endau-Rompin, Pahang, Peninsular Malaysia. They are Trianchoratus longianchoratus sp.n., T. malayensis Lim, 1986 and T. pahangensis Lim, 1986 from C. lucius, and T. ophicephali Lim, 1986 from C. striata. The new species differs from the Trianchoratus species hitherto described from channids and anabantoids in having two ventral anchors with a long curved inner root and one dorsal anchor with a curved inner root and lacking an outer root. A table summarizing the known species of heteronchocleidins (Trianchoratus, Eutrianchoratus and Heteronchocleidus) and Sundanonchus reported from fish hosts of different families (Channidae, Helostomatidae, Anabantidae and Osphronemidae) is provided.
  2. Soo OYM, Tan WB
    Parasitol Int, 2021 Jan 11.
    PMID: 33444771 DOI: 10.1016/j.parint.2021.102282
    Hamatopeduncularia longiangusticirrata sp. nov. and H. petalumvaginata sp. nov. were collected from Arius maculatus and Nemapteryx caelata, respectively from Tanjung Karang, Peninsular Malaysia. Morphological and molecular investigations were carried out to ascertain the identity of the new species. The two new species differ from previously described Hamatopeduncularia species in the morphology of the male and female reproductive organs. Hamatopeduncularia longiangusticirrata sp. nov. possesses a long penis similar to H. elongata, H. longicopulatrix, H. brisbanensis, H. major and H. petalumvaginata sp. nov., but differs in having a thread-like tapering distal end and can be distinguished from H. brisbanensis and H. major in not having an accessory piece. Hamatopeduncularia longiangusticirrata sp. nov. is also unique in having an ornamented penis initial and a vaginal tube surrounded by fine hair-like structures. Hamatopeduncularia petalumvaginata sp. nov. possesses a simple penis without an accessory piece and a petaloid vaginal opening that resembles the arrangement of petals on a flower. Maximum likelihood trees were constructed from partial 28S and 18S rDNA sequences of the two new species and other ancylodiscoidids to reveal a strongly supported monophyletic branch consisting of the two new species for both markers. According to Lim's classification in 1996 of Hamatopeduncularia species penis type, H. petalumvaginata sp. nov. has been classified within the elegans-type and H. longiangusticirrata sp. nov. is proposed as the longiangusticirrata-type.
  3. Lim LH, Tan WB, Gibson DI
    Syst Parasitol, 2010 Jun;76(2):145-57.
    PMID: 20437220 DOI: 10.1007/s11230-010-9242-2
    Monogeneans identified as Sinodiplectanotrema malayanum n. sp. were collected from the fish Pennahia anea (Sciaenidae) off the west coast of Peninsular Malaysia. The new species is recognised on the basis of morphometrical differences in the anchors, marginal hooks and eggs and apparent differences in the 28S rDNA sequence data. The new species possesses features (ovary looping the intestinal caecum, body spines, a vagina and haptoral reservoirs) not noted in the original description of the type and only other species of the genus, S. argyrosomus Zhang, 2001, necessitating the re-assignment of the genus to the Diplectanidae Monticelli, 1903, a move which is supported by 28S rDNA evidence. Sinodiplectanotrema is redefined on the basis of the observation of several features not included in the original diagnosis.
  4. Wong WL, Tan WB, Lim LH
    J. Helminthol., 2006 Mar;80(1):87-90.
    PMID: 16469180
    Hard structures of helminths have often been used for taxonomic identification but are usually not clearly defined when treated with conventional methods such as ammonium picrate-glycerin for monogeneans and glycerin for nematodes. The present study reports a rapid and simple technique to better resolve the hard parts of selected monogeneans and nematodes using 5-10% alkaline sodium dodecyl sulphate (SDS). In comparison with established methods, SDS-treated worms become more transparent. In monogeneans treated with SDS, clear details of the hooks, hook filaments, anchors, bars and the sclerotized copulatory organs could be observed. In SDS-treated nematodes, spicules and ornamentations of the buccal capsules could be clearly seen.
  5. Khang TF, Soo OY, Tan WB, Lim LH
    PeerJ, 2016;4:e1668.
    PMID: 26966649 DOI: 10.7717/peerj.1668
    Background. Anchors are one of the important attachment appendages for monogenean parasites. Common descent and evolutionary processes have left their mark on anchor morphometry, in the form of patterns of shape and size variation useful for systematic and evolutionary studies. When combined with morphological and molecular data, analysis of anchor morphometry can potentially answer a wide range of biological questions. Materials and Methods. We used data from anchor morphometry, body size and morphology of 13 Ligophorus (Monogenea: Ancyrocephalidae) species infecting two marine mugilid (Teleostei: Mugilidae) fish hosts: Moolgarda buchanani (Bleeker) and Liza subviridis (Valenciennes) from Malaysia. Anchor shape and size data (n = 530) were generated using methods of geometric morphometrics. We used 28S rRNA, 18S rRNA, and ITS1 sequence data to infer a maximum likelihood phylogeny. We discriminated species using principal component and cluster analysis of shape data. Adams's K mult was used to detect phylogenetic signal in anchor shape. Phylogeny-correlated size and shape changes were investigated using continuous character mapping and directional statistics, respectively. We assessed morphological constraints in anchor morphometry using phylogenetic regression of anchor shape against body size and anchor size. Anchor morphological integration was studied using partial least squares method. The association between copulatory organ morphology and anchor shape and size in phylomorphospace was used to test the Rohde-Hobbs hypothesis. We created monogeneaGM, a new R package that integrates analyses of monogenean anchor geometric morphometric data with morphological and phylogenetic data. Results. We discriminated 12 of the 13 Ligophorus species using anchor shape data. Significant phylogenetic signal was detected in anchor shape. Thus, we discovered new morphological characters based on anchor shaft shape, the length between the inner root point and the outer root point, and the length between the inner root point and the dent point. The species on M. buchanani evolved larger, more robust anchors; those on L. subviridis evolved smaller, more delicate anchors. Anchor shape and size were significantly correlated, suggesting constraints in anchor evolution. Tight integration between the root and the point compartments within anchors confirms the anchor as a single, fully integrated module. The correlation between male copulatory organ morphology and size with anchor shape was consistent with predictions from the Rohde-Hobbs hypothesis. Conclusions. Monogenean anchors are tightly integrated structures, and their shape variation correlates strongly with phylogeny, thus underscoring their value for systematic and evolutionary biology studies. Our MonogeneaGM R package provides tools for researchers to mine biological insights from geometric morphometric data of speciose monogenean genera.
  6. Yousef Kalafi E, Tan WB, Town C, Dhillon SK
    BMC Bioinformatics, 2016 Dec 22;17(Suppl 19):511.
    PMID: 28155722 DOI: 10.1186/s12859-016-1376-z
    BACKGROUND: Monogeneans are flatworms (Platyhelminthes) that are primarily found on gills and skin of fishes. Monogenean parasites have attachment appendages at their haptoral regions that help them to move about the body surface and feed on skin and gill debris. Haptoral attachment organs consist of sclerotized hard parts such as hooks, anchors and marginal hooks. Monogenean species are differentiated based on their haptoral bars, anchors, marginal hooks, reproductive parts' (male and female copulatory organs) morphological characters and soft anatomical parts. The complex structure of these diagnostic organs and also their overlapping in microscopic digital images are impediments for developing fully automated identification system for monogeneans (LNCS 7666:256-263, 2012), (ISDA; 457-462, 2011), (J Zoolog Syst Evol Res 52(2): 95-99. 2013;). In this study images of hard parts of the haptoral organs such as bars and anchors are used to develop a fully automated identification technique for monogenean species identification by implementing image processing techniques and machine learning methods.

    RESULT: Images of four monogenean species namely Sinodiplectanotrema malayanus, Trianchoratus pahangensis, Metahaliotrema mizellei and Metahaliotrema sp. (undescribed) were used to develop an automated technique for identification. K-nearest neighbour (KNN) was applied to classify the monogenean specimens based on the extracted features. 50% of the dataset was used for training and the other 50% was used as testing for system evaluation. Our approach demonstrated overall classification accuracy of 90%. In this study Leave One Out (LOO) cross validation is used for validation of our system and the accuracy is 91.25%.

    CONCLUSIONS: The methods presented in this study facilitate fast and accurate fully automated classification of monogeneans at the species level. In future studies more classes will be included in the model, the time to capture the monogenean images will be reduced and improvements in extraction and selection of features will be implemented.

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