Rhabdochona(Rhabdochona)hypsibarbin. sp. (Nematoda: Rhabdochonidae) from the Freshwater Cyprinid FishHypsibarbus wetmorei(Smith) in Northeast Thailand

Abstract

A new nematode species, Rhabdochona (Rhabdochona) hypsibarbi n. sp. (Rhabdochonidae), is described from the intestine of the freshwater cyprinid fish Hypsibarbus wetmorei (Smith) in the Mekong River, Nakhon Phanom Province, northeast Thailand. It is mainly characterized by medium-sized, bifurcate deirids, the presence of 14 anterior prostomal teeth and distinct basal teeth, length ratio of the muscular and glandular portions of esophagus (1:6-9), length of the left spicule (669-774 μm), absence of a dorsal barb on the right spicule, length ratio of spicules (1:4.9-6.0), arrangement of genital papillae, and smooth eggs without filaments or swellings. In addition, specifically unidentified fourth-stage larvae of Rhabdochona (Rhabdochona) sp., morphologically similar to R. hypsibarbi, were recorded from the red-tailed tinfoil Barbonymus altus (Günther) (Cyprinidae) in the Mekong River, Nakhon Phanom Province, northeast Thailand. Rhabdochona hypsibarbi is the fourth nominal species of Rhabdochona Railliet, 1916 reported from fishes in Thailand and the second species of the nominotypical subgenus found in this country.

Morphological and molecular evidence for a new rhabdochonid species, Rhabdochona (Nematoda: Rhabdochonidae), parasitizing Eugerres mexicanus (Perciformes: Gerreidae), from the Lacantún River in the Biosphere Reserve of Montes Azules, Chiapas, Mexico

“…The number of prostomal teeth, the shape of deirids, the presence or absence of superficial formations on eggs, the shape of the distal tip of the larger spicule and the number of postcloacal papillae in males, have been shown to be the most important interspecific characteristics that help in the discrimination of species of Rhabdochona (Caspeta-Mandujano & Moravec, 2000;, 2002Moravec, 1968Moravec, , 1972Moravec, , 1975Moravec, , 1978Moravec, , 2010Moravec et al, 2008Moravec et al, , 2009Moravec et al, , 2013Moravec, Bilal et al, 2012).…”

“…Rhabdochona includes more than 100 valid species parasitizing freshwater fish in all zoogeographical regions (Caspeta-Mandujano et al, 2020;Moravec et al, 2013;Santacruz et al, 2019) León, 1998;R. mexicana Caspeta-Mandujano, Moravec et Salgado-Maldonado, 2000;R.…”

First report of Rhabdochona acuminata (Nematoda, Rhabdochonidae) in Astyanax aff. fasciatus (Characiformes, Characidae) from Lake Guaíba, southern Brazil

“…The genus Rhabdochona was proposed to accommodate Dispharagus denudatus Dujardin, 1845 (= Rhabdochona denudata (Dujardin, 1845) Railliet, 1916), a parasite of Scardinius erythrophthalmus (Linnaeus, 1758). Until now, 98 to 104 species were described for this genus, presenting a wide geographical distribution (Mejía-Madrid et al 2007;Moravec et al 2013). According to Moravec (2010), the species of Rhabdochona originated from a marine ancestral in the Cretaceous period, where regions between seas and rivers alternated incessantly and formed rivers, causing a rapid speciation in host fish and parasites.…”

New nematode species, Orientatractis mekongensis n. sp. (Atractidae) and Neosynodontisia suratthaniensis n. g., n. sp. (Pharyngodonidae) from freshwater fishes in Thailand

“…The available data are rather scarce (e.g. Pearse, 1933;Ratanasritong & Kliks, 1972;Sirikanchana, 1982;Moravec et al, 1999Moravec et al, , 2013Boonchot & Wongsawad, 2005;Lerssutthichawal & Supamattaya 2005;Purivirojkul, 2009;Moravec & Yooyen, 2011a, b;Moravec & Kamchoo, 2012;Sriwongpuk, 2013) and no atractid or pharyngodonid nematodes have so far been reported there from fish hosts in natural waters.…”