Based on light and scanning electron microscopical studies, the following five gonad-infecting species of the Philometridae (Nematoda: Dracunculoidea) are described from marine perciform fishes off the eastern coast of India (Bay of Bengal): Philometra sphyraenae sp. n. (males and females) from the pickhandle barracuda Sphyraena jello Cuvier (Sphyraenidae), Philometra gerrei sp. n. (males and females) from the whipfin silver-biddy Gerres filamentosus Cuvier (Gerreidae), Philometra otolithi sp. n. (single female) from the tigertooth croaker Otolithes ruber (Bloch et Schneider) (Sciaenidae), Philometra sp. (females) from the Belanger's croaker Johnius belangerii (Cuvier) (Sciaenidae), and Philometroides eleutheronemae sp. n. (females) from the fourfinger threadfin Eleutheronema tetradactylum (Shaw) (Polynemidae). All new species are distinguished from their congeners parasitizing gonads of marine fishes by morphological (mainly the gubernaculum structure in males and the shape and structure of the cephalic and caudal ends and of the oesophagus in females) and biometrical features. Philometra rajani Mukherjee, 1963 is considered a species inquirenda.
A new species of trichosomoidid nematode, Huffmanela paronai sp. n., is established on the basis of its egg morphology and biological characters. The dark-shcllcd, cmbryonatcd eggs of this histozoic parasite occur in masses in the epidermis of the swordfish Xiphias gladius L. (Xiphiidae, Perciformes) from the Ligurian Sea in northern Italy. The eggs are concentrated in groups appearing as black spots in the skin of the fish host, being distributed mainly on the lower part of its body (lower jaw, gill covers, pectoral, anal and caudal fins, lower half of body). The parasite’s eggs are characterised mainly by their shape and markedly small size (48-51 x 21-24 pm), an aspinose surface, relatively small polar plugs, and thick egg wall (3 pm). This is the first Huffmanela species reported from fish in Europe.
A new nematode, Myleusnema bicumis gen. et sp. п., is described from the intestine of a characoid freshwater fish, Myleus ternetzi (Norman, 1929) (Cypriniformes: Serrasalmidae), from French Guiana. This cosmocercoid nematode species represents a new genus of the family Kathlaniidae, being characterized mainly by the shape of the body (the cephalic portion is separated from the rest of the body at the level of the nerve ring), structure of the cephalic extremity (presence of three lips and three lamella-like formations demarcating the buccal cavity), absence of an oesophageal pharynx, presence of medium-sized alate spicules (0.694-0.721 mm long), two conspicuous postcloacal homs associated with a gubernaculum, and by the number and distribution of caudal papillae in the male.
A new kathlaniid nematode, Myleusnema brasiliense sp. n„ is described from the intestine of a characoid fish, Myleus sp. (Serrasalmidae, Cypriniformes), from Brazil, It differs from the only other congeneric species Myleusnema bicornis Moravec et Thatcher, 1996 mainly in having an unseparated cephalic portion of the body, lips provided with Hanges with numerous spikelike appendages, deirids situated more posteriorly, more numerous (8 pairs) subventral preanal papillae in the male, and distinctly longer spicules (1.58-1.70 mm). The species description is based on light microscopic and scanning electron microscopic (SF,M) observations.
Recent examinations of newly obtained materials of dracunculoid nematodes (Dracunculoidea) parasitizing marine fishes off New Caledonia, South Pacific, revealed the presence of several nematodes of the genera Philometra Costa, 1845 (Philometridae) and Ichthyofilaria Yamaguti, 1935 (Guyanemidae), including the following four new species: Philometra priacanthi sp. n. (males) from the gonads of Priacanthus hamrur (Forsskål) (Priacanthidae), Philometra tenuicauda sp. n. (male and mature and gravid females) from the gonads of Lagocephalus sceleratus (Gmelin) (Tetraodontidae), Philometra dentigubernaculata sp. n. (males) from the oculo-orbit of Tylosurus crocodilus (Péron et Lesueur) (Belonidae), and Ichthyofilaria novaecaledoniensis sp. n. (subgravid female) from the musculature of Hoplichthys citrinus Gilbert (Hoplichthyidae). The new species are characterized mainly by the length and structure of spicules and the gubernaculum, body size, location in the host and by the type of hosts. In addition, the findings of Philometra lethrini Moravec et Justine, 2008 from the gonads of Lethrinus miniatus (Forster) and L. variegatus Valenciennes (both Lethrinidae) represent new host records for this parasite; for the first time, its subgravid females were found to be up to 350 mm long. The occurrence of Philometra ocularis Moravec, Ogawa, Suzuki, Miyazaki et Donai, 2002 in the oculo-orbit of Epinephelus areolatus (Forsskål) (Serranidae) off New Caledonia was confirmed.
The morphology of the nematode Klossinemella iheringi (Travassos, Artigas et Pereira, 1928), the type species of the genus Klossinemella Costa, 1961, was studied using specimens collected from the serrasalmid fish, Mylesinus paraschomhurgkii légu, Santos et Ferreira, 1989 (a new host record), from the Trombetas River, Para State, Brazil, by both light and scanning electron microscopy. This species was also recorded from the Jari River (Pará State), the Uatuma, Pitinga and Capucapu Rivers (Amazonas State), and the Araguari River (Amapá State). An examination by SEM made it possible, for the first time in this genus, to study in detail the structure of the cephalic end. Characteristic features are the presence of 8 cephalic papillae arranged in two circlets, well developed lateral amphids, and especially a crown of 8 cephalic, Y-shaped sclerotized pieces (outgrowths). The male possesses 8 pairs of caudal papillae (3 preanals, 1 adanal and 4 postanals), two unequal spicules (0.156-0.294 mm and 0.069-0.099 mm long) and a gubemaculum (0.027-0.045 mm in length); previously undescribed deirids were also found. This is the first record of this parasite from the Amazon River basin. The genus Proatractis G. Caballero, 1971 is considered a synonym of Klossinemella Costa, 1961, belonging to the cosmocercoid family Atractidae, and its type species is transferred to the latter genus as Klossinemella parvicapilico-rnnala (G. Caballero, 1971) comb. n.
Adult specimens of five little-known species of spiruridan nematodes (Spirurida) were collected during occasional examinations of some fishes from the Poonch River in Jammu and Kashmir, India: Procamallanus (Spirocamallanus) bilaspurensis Gupta et Duggal, 1973 in Mastacembelus armatus (Lacépède) (Mastacembelidae, Synbranchiformes), Rhabdochona (Rhabdochona) indica Moravec, Scholz, Ash et Kar, 2010 in Crossocheilus latius (Hamilton) (Cyprinidae, Cypriniformes), Rhabdochona (Rhabdochona) turkestanica (Skryabin, 1917) in Schizothorax richardsonii (Gray) (Cyprinidae, Cypriniformes) and both Rhabdochona (Rhabdochona) hospeti Thapar, 1950 and Rhabdochona (Globochona) cf. chodukini Osmanov, 1957 in Tor putitora (Hamilton) (Cyprinidae, Cypriniformes); besides these, unidentifiable physalopterid larvae were recorded from M. armatus and T. putitora. Their detailed light and electron microscopical studies revealed some taxonomically important, previously not observed features and made possible their redescription. Fourth-stage larvae of P. (S.) bilaspurensis and R. (R.) turkestanica are described for the first time. The latter is resurrected as an independent species. The following are considered to be species inquirendae: a total of nine poorly described species of Rhabdochona Railliet, 1916 from T. putitora in Balochistan, Pakistan, all listed in the monograph of Kakar et al. (2011), plus an additional 15 species of the genus reported from cyprinids and a catfish in the same region (Balochistan) by the same authors. Also three congeneric species from India (R. nemacheili Rautela et Malhotra, 1982, R. putitora Kaur et Khera, 1991 and R. tori Gupta et Srivastava, 1982) and one from Pakistan (R. charsaddiensis Siddiqi et Khattak, 1984) should be considered as species inquirendae due to their poor descriptions. The names of Rhabdochona putitori Anjum, 2013, R. indusi Soofi, Birmani et Dharejo, 2017 and R. sindhicus Soofi, Birmani, Dharejo, Abbasi et Ghachal, 2020 are invalid according to the International Code of Zoological Nomenclature.
Specimens of three little-known species of Rhabdochona (Nematoda: Rhabdochonidae) were collected during occasional examinations of some freshwater fishes in India: R. (Rhabdochona) hellichi turkestanica (Skryabin, 1917) in Schizothorax sp. (Cyprinidae, Cypriniformes) from the Lodhomakhola and Rangit Rivers, West Bengal and Sikkim, respectively; R. (R.) hospeti Thapar, 1950 in Tor sp. (Cyprinidae) from the Rangit River; and R. (Globochona) mazeedi Prasad et Sahay, 1965 in Clupisoma garua (Hamilton) (Schilbeidae, Siluriformes) from the Farakka Dam Lake, West Bengal. Their detailed light and electron microscopical studies revealed some taxonomically important, previously not observed features and made possible their redescription. Fourth-stage larvae of R. hospeti are described for the first time. Rhabdochona hellichi turkestanica (syns. R. denudata filamentosa Bykhovskaya-Pavlovskaya, 1936, R. kashmirensis Thapar, 1950, R. schizothoracis Siddiqi et Khattak, 1984) is proposed as a subspecies, differing from the nominotypical subspecies R. hellichi hellichi (Šrámek, 1901) mainly in the shape of the distal end of the left spicule, molecular data and geographical distribution. Rhabdochona moraveci Katoch et Kalia, 1991 (a homonym to R. moraveci Duggal et Kaur, 1987) is renamed R. indica nom. n. The following six species are considered new junior synonyms of R. hospeti: Comephronema [sic] mackiewiczi Malhotra et Rautela, 1984, Rhabdochona moraveci Duggal et Kaur, 1987, R. bifidum Kakar et Bilqees, 2007, R. uvaginus Kakar et Bilqees, 2007, R. bolani Kakar, Bilqees et Ahmad, 2008 and R. cephalodiverticula Kakar, Bilqees et Ahmad, 2008. Rhabdochona edentati Paul et Majumdar, 1994 is considered a species incertae sedis.
Specimens of the type species of the ascaridoid genus Iheringascaris Pereira, 1935, I. inquies (Linton, 1901) (Anisakidae), were collected from the digestive tract and mesentery of its type host Rachycentron canadum (Linnaeus) (Rachycentridae, Perciformes) from off the Atlantic coast of South Carolina, USA, during May of 2011. Scanning electron microscopical examination, used for the first time for specimens originating from the West Atlantic, made it possible to study in detail some taxonomically important morphological features, such as the number and distribution of male caudal papillae, cephalic and cuticular structures, deirids and cloacal (anal) lips. The allocation of other, poorly described, species from different hosts in Indian waters to this genus needs to be confirmed.
The following three species of the Philometridae (Nematoda: Dracunculoidea) are described from marine perciform fishes of the Everglades National Park (northern Gulf of Mexico), Florida, USA: Philometra brevispicula sp. n. (male and females) from the subcutaneous tissue of mouth of the gray snapper Lutjanus griseus (Linnaeus) (Lutjanidae), Philometroides grandipapillatus sp. n. (only females) from pectoral fin muscle of the crevalle jack Caranx hippos (Linnaeus) (Carangidae), and Caranginema americanum Moravec, Montoya-Mendoza et Salgado-Maldonado, 2008 (females) from the subcutaneous fascia of trunk muscle in crevalle jack C. hippos. Philometra brevispicula is mainly characterized by small cephalic papillae of the external circle, the absence of oesophageal teeth and the presence of small caudal projections in gravid female, markedly short spicules (45 µm) in male, and by its location in the host. Philometroides grandipapillatus differs from congeners mainly in the shape of the cephalic region (narrow, conspicuously protruding), large cephalic papillae of the external circle and the absence of caudal projections in female, and by the site of infection in the host. Caranginema americanum is for the first time recorded from the northern Gulf of Mexico.