PURPOSE: The purpose is to describe the new species morphologically and molecularly and provide new information of its evolutionally relationships with other species of the subgenus.
METHODS: Standard methods of collection and examination of marine hosts, processing and illustrating of specimens, and taxonomic identification of parasites using the extensive collection of the lead author were used. Specimens were further studied using energy-dispersive X-ray analysis and ion sectioning of hooks, SEM analysis, and molecular sequencing. Type specimens were deposited at the Harold W. Manter Lab. collection, Lincoln, Nebraska.
RESULTS: Acanthogyrus (Acanthosentis) fusiformis n. sp. is described from the catfish, Arius sp. (Ariidae: Siluriformes) off the Pacific Coast of Vietnam at Bac Lieu in the Gulf of Thailand. The three other marine Indian species include A. (A.) arii Bilqees, 1971 which is also described from a similar catfish, Arius serratus Day off the Karachi coast in the Arabian Sea, Indian Ocean. Our new species from Vietnam is distinguished from the other 46 species by a combination of characters including a small fusiform trunk, complete circles of small hollow spines covering the entire trunk, prominent double apical organs often extending posteriorly past posterior hooks, middle and posterior hooks of equal size slightly smaller than anterior hooks, large neck continuous with the outline of the proboscis without distinct separation, big drop-shaped cephalic ganglion, extension of the proboscis receptacle anteriorly past the base of the proboscis up to the insertion point of the posterior hooks, presence of two para-receptacle structures (PRSs), free unattached thick lemnisci, short female reproductive system with filamentous attachment of the distal end of the uterine bell to the ventral body wall, and small narrowly ellipsoid eggs with thickened polar ends. Partial sequences of the 18S and internal transcribed spacers (ITS1-5.8S-ITS2) of ribosomal RNA were generated and used for phylogenetic analyses to confirm the taxonomic identity of Acanthogyrus (Acanthosentis) fusiformis n. sp.
CONCLUSIONS: We describe unique morphological features of A. fusiformis never before known in the subgenus Acanthosentis. The uniqueness of A. fusiformis is further demonstrated by its EDXA fingerprint characterized by high levels of calcium and phosphorous in hooks. The zoogeography of species of Acanthosentis is elucidated in the Indian subcontinent, the Caribbean, China, and Africa. Molecular data have been available only in few species of Acanthogyrus (Acanthosentis) to date on GenBank database. For 18S, only two sequences from unknown Acanthosentis sp. from India are available, while for the ITS1-5.8S-ITS2 region, only sequences of A. cheni from China and of two unidentified species from Malaysia are available. Additional studies of species of Acanthosentis based on morphological and molecular genetic data will be needed to reconstruct the evolutionary history and phylogenetic affinities of this group of acanthocephalans.
Objective: This study aimed to determine the prevalence of third molar impaction and related pathologic conditions in a cohort of patients living in North-eastern Peninsular Malaysia.
Methods: In this retrospective study, 490 orthopantomograms (OPGs) of patients who were referred to the Oral and Maxillofacial Surgery department between January 2010 and December 2019 were assessed. Data including age, gender, ethnicity, frequency of third molar impactions, their angulations and levels of eruption, retromolar space, and associated pathologic conditions were collected. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) version 24.0. The significance level was set to P < 0.05.
Results: A total of 490 patients with a mean age of 28.87 years (range: 20-64) demonstrated 1957 impacted third molars (1022 mandibular + 935 maxillary). Impacted third molars were more likely present in females than males (1:2.20) (p < 0.05); and in Malay-ethnic (44.49%) patients followed by Chinese (34.45%) and Indians (21.02%). Mesioangular was the most common angulation of impaction both in the maxilla (24.68%) and mandible (18.34%). The most common pattern of third molar impaction was IIA (61.67%), and the retromolar space was significantly larger in males (13.6 mm; P < 0.05) than females (11.6 mm). The most frequently occurring pathological condition associated with third molars impaction is dental caries in the second or third molar (15.38%).
Conclusions: This study highlights mesioangular impaction with their occlusal plane at the same level as the occlusal plane of the adjacent tooth being the most prevalent pattern of third molar impaction in North-eastern Peninsular Malaysia.