Development of Procamallanus saccobranchi (Nematoda: Camallanidae), a parasite of a freshwater fish in India

The development of the nematode Procamallanus saccobranchi Karve, 1952, a parasite in the stomach of the fish Heteropneustes fossilis (Bloch), was studied in Mesocyclops crassus (Fischer) and Mesocyclops leuckarti (Claus). After being ingested by the copepods the nematode first-stage larvae penetrated into the haemocoel of the intermediate host; there they moulted twice (on days 3 and 5 p.i. at 28-30 degrees C) attaining the third, infective stage. The definitive host H. fossilis acquired infection by feeding on copepods harbouring infective-stage larvae; in the stomach of this definitive host, the larvae were observed to undergo two more moults. The third moult occurred on day 13 p.i. and the fourth moult on day 38 p.i. and day 66 p.i. in "male" and "female" larvae, respectively. The larval stages, including the moulting forms are described and illustrated.     

Camallanus cotti (Nematoda: Camallanidae), an introduced parasite of fishes in New Caledonia

A pathogenic Asian nematode species of Camallanus, C. cotti Fujita, 1927, was found in New Caledonia, South Pacific, for the first time; it was recorded from two native fishes, Awaous guamensis (Valenciennes) (Gobiidae) (prevalence 51%, intensity 1-25) and Kuhlia marginata (Cuvier) (Kuhliidae) (a single specimen found), of the La Foa River, about 100 km north of Nouméa; the latter represents a new host record. Morphological data on C. cotti based on New Caledonian specimens and those previously collected from aquarium-kept Misgurnus anguillicaudatus (Cantor) in Canada have been provided. The SEM examination of C. cotti, applied for the first time in this species, made it possible to study some of its morphological details; first-stage larvae from the female's uterus were found to possess several digit-like processes on the tail tip, not previously reported for any species of the Camallanidae. Camallanus moraveci Petter, Cassone et France, 1974 is considered a junior synonym of C. cotti. A list of hitherto recorded hosts of C. cotti is provided. Camallanus cotti is assumed to be introduced into New Caledonia along with the introduction of the exotic poeciliid fishes, which are known to be among the most common hosts of C. cotti in aquarium cultures worldwide.     

伞滑刃线虫属分种检索

依据2004年以前发表的所有伞滑刃属新种原始报道的资料,分析了伞滑刃属73个相关种的所有形态学分类特征,编制了64个伞滑刃属有效种的分类检索表.     

Validation of morphological keys for identification of Bursaphelenchus xylophilus (Nematoda,Parasitaphelenchidae) to group and species level

Official analyses undertaken in the framework of an official survey, or import controls need reliable results. This can be achieved by using validated methods. For morphological tests, this validation process is rarely illustrated despite guidance provided in EPPO PM 7/98 (1) Specific requirements for laboratories preparing accreditation for a plant pest diagnostic activity. This paper presents validation for the morphological identification of Bursaphelenchus xylophilus, with the evaluation results of published identification keys and of internally designed identification keys at B. xylophilus group and species levels. For published identification keys some criteria were shown not to be reliable for routine use: excretory pore position and number of caudal papillae. The key designed in the laboratory for xylophilus group identification was shown to be sensitive and specific when one male and one female were observed. The key designed for B. xylophilus species identification is sensitive, specific and reproducible if only one female of B. xylophilus is observed. The tools designed were validated as simple and reliable for routine analysis. The advantages and limitations of the validation process for morphological tools are discussed for process improvement.     

Post-embryonic development of Camallanus cotti (Nematoda: Camallanidae), with emphasis on growth of some taxonomically important somatic characters

In this paper, the quantitative post-embryonic development of the Asian freshwater fish nematode Camallanus cotti Fujita, 1927, is described. Larval and adult morphometrics were obtained by following the parasite's life cycle experimentally using copepods Macrocyclops albidus (Jurine) as intermediate host and guppies Poecilia reticulata (Peters), southern platyfish Xiphophorus maculatus (Günther) and paradise fish Macropodus opercularis (L.) as definitive host. Additionally, adult worms were obtained from heavily infected paradise fish imported from Singapore. It is suggested that the gradual change in proportions of the worm's somatic body parts reflects the specific ecological role of each developmental stage. The free-living infective first-stage larva seems to be adapted for transmission, as indicated by its relatively long tail, designed to generate host-attracting movements, and its non-functional intestine. The second- and third-stage larvae from the copepod intermediate host seem mainly to invest in trophic functionality, i.e., the development of the buccal capsule and the oesophagus, which are crucial structures for the worm's successful establishment in the definitive fish host. Once in the fish intestine, the larvae enter a period of considerable growth. After the fourth (i.e., last) moult, a 72% increase in average female body length occurs. This is accompanied by doubling the average vulva-tail tip distance and the average tail length. The length of the female hind body expands in an accelerating allometric fashion, and seems to be closely linked to the posterior-wards expansion of the uterus. In the males however, growth seems to cease after the final moult. We conclude that female post-maturational body size, but especially the length of the hind body and the tail, are closely related to reproductive state, i.e., the developmental stage of the offspring in the uterus, and, probably, the worms' age. Any future taxonomical studies of camallanids in general, and C. cotti in particular, should thus be aware of the reproductive state of the females used.     

Two new gonad-infecting Philometra species (Nematoda: Philometridae) from the marine fish Lutjanus vitta (Perciformes: Lutjanidae) off New Caledonia

Two new gonad-infecting species of Philometra Costa, 1845 (Philometridae), P. brevicollis sp. n. and P. mira sp. n., are described from the ovary of the brownstripe red snapper, Lutjanus vitta (Quoy et Gaimard) (Lutjanidae, Perciformes), from the South Pacific Ocean off the coast of New Caledonia. Based on light and scanning electron microscopy examination, these new nematodes are compared with all other gonad-infecting species of Philometra. The former species (males and mature and gravid females available) mainly differs from its congeners in the length of males (5.39-5.92 mm), equally long spicules (279-312 microm), and the gubernaculum (151-168 microm), in that the distal end of the gubernaculum bears dorsolateral transverse lamella-like structures, and in the structure of the male caudal end. The latter species (only males available) is characterized by the length of males (3.47-3.66 mm), equally long spicules (96-105 microm), and the gubernaculum (78-84 microm), the absence of a dorsal reflected barb or lamella-like structures on the distal end of gubernaculum, and by the structure of the male caudal end. Judging from the occurrence in the host, P. brevicollis is the main philometrid parasitizing the gonads of L. vitta, in which it can reproduce, whereas this fish probably serves as only the paradefinitive host for P. mira. Both P. brevicollis and P. mira are the first nominal species of Philometra described from fishes of the family Lutjanidae.     

Taxonomical study into two new species of Philometra (Nematoda: Philometridae) previously identified as Philometra lateolabracis (Yamaguti, 1935)

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, Lateolabraxjaponicus (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 relationship between species within the Xiphinema americanum-group (Nematoda: Dorylaimida)1

Principal components and hierarchical cluster analysis based on morphometric characters of the type populations of the 39 species attributed to the Xiphinema americanum-group confirmed the occurrence of five subgroups. The use of a single character is generally insufficient to characterize a species because of the wide intra-population and intra-specific variations. Hierarchical cluster analysis, although impractical for species/population identification, appears useful in the study of the relationships between species or groups of species.     

山西省窖藏薯类块茎中2种短体线虫的种类鉴定

本文采用传统形态学与分子生物学相结合的方法,对采自山西省窖藏马铃薯和薯蓣块茎中的短体线虫进行了种类鉴定.结果 表明,从马铃薯块茎中分离出的短体线虫形态学特征与斯克里布纳短体线虫Pratylenchus scrib-neri一致,其SSU序列与P.scribneri美国群体相似性达99.8％.从薯蓣块茎中分离出的短体线虫...     

Structure of the cephalic end of Ascarophis mexicana (Nematoda: Cystidicolidae), as revealed by SEM

Scanning electron microscopy of the cystidicolid nematode Ascarophis mexicana Moravec, Salgado-Maldonado et Vivas-Rodríguez, 1995 enabled the first detailed study of its cephalic structure. In contrast to most Ascarophis species, its pseudolabia are highly reduced and sublabia are unlobed and weakly developed. Similascarophis is considered a synonym of Ascarophis, to which two its species are transferred as A. maulensis (Mu?oz, González et George-Nascimento, 2004) comb. n. and A. chilensis (Mu?oz, González et George-Nascimento, 2004) comb. n.     

Some new data on the morphology of the nematode Lappetascaris lutjani Rasheed, 1965 (Nematoda: Anisakidae)

The nematode, Lappetascaris lutjani, recovered from the fish, Pellona ditchela from West Bengal, India, was studied by light and scanning electron microscopes. Surface features of the head and tail ends of the body as also the distal parts of the spicules were described, illustrated and discussed with regard to the available data relative to this species. Present LM studies provide information concerning the head structure in greater detail and existence of narrow but distinct lateral cervical alae. SEM studies give microtopographic details of the worm. Some of these represent new information and might be useful in the taxonomic evaluation of this interesting nematode. P. ditchela is the recorded new host of L. lutjani.     

Two new species of Rhabdochona (Nematoda: Rhabdochonidae) from freshwater fishes in Thailand

Two new species ofrhabdochonid nematodes are described from the intestine of freshwater fishes in Chiang Mai Province, northern Thailand: Rhabdochona (Rhabdochona) pseudomysti sp. n. from the catfish Pseudomystus siamensis (Regan) (Bagridae, Siluriformes) in the Fang Brook, a tributary of the Kok River (the Mekong River basin), Fang District and Rhabdochona (Globochona) thaiensis sp. n. from the cyprinid Mystacoleucus marginatus (Valenciennes) (Cyprinidae, Cypriniformes) in the Ping River (the Chao Phraya River basin), Muang District. Rhabdochona pseudomysti is mainly characterized by simple, leaf-like oval deirids (a unique feature among Rhabdochona spp.), a prostom with 14 anterior teeth, the presence of basal prostomal teeth, the length ratio of the muscular and glandular portions of oesophagus (1:2.1-2.6), an unusually long left spicule (1.10-1.22 mm), length ratio of spicules (1:11.5-14.7), arrangement of genital papillae, and conspicuously elevated vulval lips. Rhabdochona thaiensis differs from other representatives of the subgenus Globochona Moravec, 1972 possessing caudal projections on the tail tip in that it has only 2 claw-shaped projections located ventrally on the tail tip of both males and females; the species is mainly characterized by the presence of distinct pseudolabia, 8 anterior prostomal teeth, absence of basal teeth, bifurcated deirids, length ratio of the muscular and glandular portions of oesophagus (1:11.3-11.9), conspicuously short (135-141 microm) left spicule, arrangement of genital papillae, and somewhat elevated vulval lips. Fully developed eggs of R. pseudomysti and R. thaiensis remain unknown. These are the first nominal species of Rhabdochona reported from Thailand.