A description is given of the life cycle of the nematode Procamallanus (Spirocamallanus) rebecae (Andrade-Salas, Pineda-Lopez et García-Magafia, 1994), an intestinal parasite of cichlids in Mexico. The copepod Mesocyclnps sp. was found to be a suitable experimental intermediate host. After the copepod’s ingestion of free first-stage larvae of the nematode, these enter the haemocoel of the intermediate host; they moult twice (on the 3rd and 5-6th day p.i. at 21-22”C) before they attain the third, infective stage. The third-stage larva already possesses the large buccal capsule without spiral thickenings and its tail tip bears three cuticular spines. The larvae undergo two additional moults (13-14 days and 42 days p.i.) in the definitive host (Cichlasoma urophthalmus) before changing to adults; the prepatent period is about 2-3 months. Experimental infection of guppies, Poecilia reticulata, have shown that these fishes may become paratenic (metaparatenic) hosts of this parasite. The morphology of individual larval stages of this nematode is described.
Subulurid nematodes identified as Subulura halli Barreto, 1918 were collected from the endangered bird Otis tarda Linnaeus (Gruiformes: Otididae) in China. A detailed redescription of the hitherto poorly known species is presented using both light and, for the first time, scanning electron microscopy. Previously unreported and erroneous morphological features of taxonomic significance are revealed. This species can be readily distinguished from its congeners by the relatively long oesophagus (1.47-1.92 mm long, representing 10.6-16.9% of body length), the number and arrangement of male caudal papillae (11 pairs in total, arranged as five pairs of precloacal and six pairs of postcloacal papillae), the equal length of spicules (1.35-1.52 mm long, representing 10.7-13.7% of body length) and the presence of a small medioventral, precloacal papilla in the male.
Males of the nematode Philometra lateolabracis (Yamaguti, 1935), the type species of the genus Philometra Costa, 1845, were discovered for the first time in gonads of its type host, the Japanese seaperch, Lateolabrax japonicus (Cuvier). Morphological comparisons carried out between the collected male and female P. lateolabracis with the male and female philometrid nematodes previously reported as P. lateolabracis infecting chicken grunt, Parapristipoma trilineatum (Thunberg), and red sea bream, Pagrus major (Temminck et Schlegel), revealed that the latter represent two new species, Philometra isaki sp. n. and Philometra madai sp. n., respectively. Molecular comparison of ITS2 rDNA between P. lateolabracis and P. madai supported the morphological conclusion that the two nematodes obtained from different fish species should be assigned to different species.
The development of the nematode Procamalianus (Spirocamallanus) neocaballeroi (Caballero-Deloya, 1977), an intestinal parasite of the characid fish, Astyanax fasciatus (Cuvier) in Mexico, was studied in the experimental copepod intermediate host, Mesocyclops sp. After the copepod’s ingestion of free first-stage larvae of the nematode, these penetrate into the haemocoel of the intermediate host; they moult twice (on the 3rd and 4-5th day p.i. at 21-22”C) before they attain the third, infective stage. The third-stage larva already possesses the large buccal capsule subdivided into an anterior broad portion with eight spiral thickenings (as observed in lateral view) and a narrow posterior portion, and its tail tip bears three conical processes. The definitive host acquires infection by feeding on infected copepods; in the intestine of this fish, the nematode larvae undergo two more moults (on the 10th and 14-15th day p.i. at 25-32°C) before attaining their maturity. The prepatent period is approximately two months.
The activity of α-amylase, glucoamylase, maltase, trehalase, glycogen phosphorylase and trehalose phosphorylase was measured in extracts from larval and adult Hysterothylacium aduncum (Rudolphi, 1802), parasitic nematode of marine fish. The content of glycogen and trehalose in the worm's body was also determined. Both the hydrolytic and phosphorolytic paths of sugar decomposition are present in H. aduncum. In the larvae glycogen was utilised mainly via the hydrolytic path. In the adults the activities of phosphorolytic enzymes were higher than in the larvae. In both stages the activity of trehalose phosphorylase is present. In adult nematodes it is uncommonly high. The dominating sugars in the adults were glucose and glycogen, while in the larvae it was trehalose.
Phylogeny of seven groups of metazoan parasitic groups is reviewed, based on both morphological and molecular data. The Myxozoa (=Malacosporea + Myxosporea) are most probably related to the egg-parasitic cnidarian Polypodium (Hydrozoa?: Polypodiozoa); the other phylogenetic hypotheses are discussed and the possible non-monophyly of the Cnidaria (with the Polypodiozoa-Myxozoa clade closest to the Triploblastica) is suggested. The Mesozoa is a monophyletic group, possibly closely related to the (monophyletic) Acoelomorpha; whether the Acoelomorpha and Mesozoa represent the basalmost triploblast clade(s) or a derived platyhelminth subclade may depend on rooting the tree of the Triploblastica. Position of the monophyletic Neodermata (=Trematoda + Cercomeromorpha) within the rhabditophoran flatworms is discussed, with two major alternative hypotheses about the neodermatan sister-group relationships (viz., the "neoophoran" and "revertospermatan"). The Myzostomida are not annelids but belong among the Platyzoa, possibly to the clade of animals with anterior sperm flagella (=Prosomastigozoa). The Acanthocephala represent derived syndermates ("rotifers"), possibly related to Seison (the name Pararotatoria comb. n. is proposed for Seisonida + Acanthocephala). The crustacean origin of the Pentastomida based on spermatological and molecular evidence (Pentastomida + Branchiura = Ichthyostraca) is confronted with palaeontological views favouring the pre-arthropod derivation of the pentastomids. Phylogenetic position of the nematodes within the Ecdysozoa and evolution of nematode parasitism are discussed, and the lack of relevant information about the enigmatic ectoproctan parasite Buddenbrockia is emphasised.
Mature specimens of the nematode Dichelyne (Cucullanellus) minutus (Rudolphi, 1819) (Ascaridida, Cucullanidae, Seuratoidea) were obtained from the intestine of flounder Platichthys flesus (L.) caught in the Øresund, Denmark. Plaice Pleuronectes platessa L. and common goby Pomatoschistus microps (Kröyer) also harbour this species. The eggs embryonate on the seabottom. Larvae about 440 µm long, and believed to be in their third stage, hatch from the eggs. These larvae are not directly infective to flounders or gobies. The polychaete Nereis diversicolor O.F. Müller acts as obligatory intermediate host. Experimental infections showed that larvae >600 µm long and provided with a chitinous tooth survived in flounder and common goby. The third-stage larvae moult to fourth-stage larvae in the fish gut wall. Mature worms occur in the lumen of the anterior part of the intestine. All developmental stages may be transferred from one flounder to another; thus the flounder may acquire the parasite also by devouring infected gobies.
Based on the original description, the nematode genus Piscinema Gambhir et Ng, 2014 and its type species, P. barakensis [sic] Gambhir et Ng, 2014 (probably a misidentified physalopterid larvae), are removed from the Philometridae, where they were allocated; they are considered a genus inquirendum and incertae sedis and a species inquirenda, respectively. The poorly described nematode Rhabdochona carpiae Nimbalkar, Deolalikar et Kamtikar, 2013 (Rhabdochonidae) appears largely fabricated and is regarded a species dubia.
Daniconema anguillae Moravec et Koie, 1987 larvae measuring 1.64-1.76 mm were occasionally found in considerable numbers in the fins and subcutaneous connective tissue of approximately 50% of eel Anguilla anguilla (L.) sampled from Lake Balaton, Hungary. The larvae were noted for their slender body, very long tail with a rounded tip, a densely transversely striated cuticle, and the presence of boring tooth and large kidney-shaped amphids on the cephalic end. The larvae could easily be recovered from the above mentioned organs by placing them into isotonic saline solution. No disease signs or pathological changes attributable to the larval infection could be observed. The only histological indication of host reaction was the appearance of macrophages adhering to the body surface of larvae and of cells with spherical nucleus in areas around the larvae. A possible life cycle pattern of I), anguillae is discussed.
Two new nematodes, Paraseuratoides ophisterni gen. et sp. n. (Seuratoidea: Quimperiidae) and Philometra ophisterni sp. n. (Dracunculoidea: Philometridae) are described based on specimens recovered from the intestine and mesentery, respectively, of the swamp-eel Ophisternon aenigmaticum Rosen et Greenwood (Synbranchiformes: Synbranchidae) from a canal of the Papaloapan River in Tlacotalpan, State of Veracruz, Mexico. The genus Paraseuratoides is most similar to Paraseuratum Johnston et Mawson, 1940, differing from it mainly in the absence of a bulbous inflation on the anterior end of the oesophagus and in the structure of the mouth (presence of 6 spines in addition to 6 oesophageal teeth). Neoquimperia Wang, Zhao, Wang et Zhang, 1979 and Wuinema Yu et Wang, 1992 are synonymised with Ezonema Boyce, 1971 and Paragendria Baylis, 1939, respectively, and Haplonema hamulatum Moulton, 1931 is considered a junior synonym of Ichthyobronema conoura Gnedina et Savina, 1930. Philometra ophisterni (only females) is mainly characterised by minute cephalic papillae, a greatly developed anterior oesophageal bulb separated from the cylindrical part of the oesophagus, anterior extension of the oesophageal gland anterior to the nerve ring, and by the character of large caudal projections. This is the first Philometra species recorded from inland fishes in Mexico.