The development of amphids and amphidial glands in adult Syngamus trachea (Nematoda: Syngamidae)

Nematode amphids are a pair of lateral cephalic sense organs, each comprising a group of sensory endings terminating in a cuticle-lined pit. In Syngamus trachea, a parasite of birds, each amphid is surrounded by two non-nervous supporting elements, a large gland cell basally and a smaller supporting cell anteriorly. The amphidial glands display high levels of secretory activity from five to six days postinfection. Secretory material is discharged through the lumen of the sense organ onto host tissue. The ultrastructure of amphids and amphidial glands has been investigated in newly moulted, immature and mature adults to trace the development of glandular activity and its effect on amphid-amphidial gland relationships. In newly moulted adults, the glands have very low levels of secretory activity and appear to act only as supporting cells to the amphids. As secretory activity increases, the gland cell membrane surrounding the sensory endings is elaborated into a reticulum which probably forms the secretory surface. In mature adults the amphid pit is swollen and filled with secretion; the sensory endings are relegated to the periphery of the lumen. It is suggested that amphidial glands develop from typical supporting cells, but acquire a new role possibly associated with parasite attachment.     

The occurrence of gapeworm (Syngamus trachea) in willow grouse.

21.4% of the willow grouse (Lagopus lagopus) examined from a coastal locality in northern Norway were infected with Syngamus trachea. None of the willow grouse examined from an inland locality with colder and longer winters were infected with the parasite. It is suggested that the parasite may influence survival of the grouse population.     

Extrusion of the residual body in spermatids of Ancylostoma caninum (Nematoda, Strongyloidea)

Transmission electron microscopy reveals that the spermatocytes of the hookworm Ancylostoma caninum contain an abundance of Golgi complexes, ribosomes, specialized membranous organelles, and long strands of smooth endoplasmic reticulum. These organelles remain abundant until the early spermatid stage of sperm development, when they reach their maximum abundance and maturity and the production of new ones ceases. Golgi complexes, ribosomes, and excess SER, which are not functional after this stage, become segregated and confined to the posterior portion of the spermatid in a polar lobe. Later, the polar lobe together with excess cytoplasmic matrix is bound by a membrane and dissociated from the spermatid as a residual body. The spermatid is then devoid of Golgi complexes and ribosomes. Formation of residual bodies as sperm cells mature may be considered a type of cell excretion.     

Prevalence and abundance of equine strongyles (Nematoda: Strongyloidea) in tropical Australia

A postmortem survey of 57 horses in tropical northern Queensland revealed 41 (89%) infected with intestinal strongyles. Thirty-five strongyle species (8 large strongyles and 27 small strongyles [Cyathostominae]) were recorded of which 9 species are reported from Australia for the first time. The 14 most prevalent small strongyles were Cyathostomum catinatum (in 76% of horses), Cyathostomum coronatum (65%), Cyathostomum pateratum (33%), Cyathostomum labiatum (30%), Cylicostephanus calicatus (70%), Cylicostephanus longibursatus (67%), Cylicostephanus goldi (43%), Cylicostephanus minutus (26%), Cylicocylus nassatus (67%), Cylicocyclus leptostomus (41%), Cylicocylus insigne (41%), Cylicocyclus radiatus (33%), Cylicocyclus brevicapsulates (22%), and Poteriostomum imperidentum (24%). The remaining cyathostomes were each found in less than 15% of horses. The 4 most common large strongyles were Triodontophorus serratus (30%), Strongylus vulgaris (28%), Strongylus equinus, and Strongylus edentatus (both 22%). The number of species of small strongyles per horse showed a marked variation (mean 10.3, range 2-21) but bore no relationship to either the total number of strongyles per horse, age, sex, and breed of horse, or season. Total number of strongyles per horse (mean 15,890, range 20-165,000) was less than in recent surveys in Europe and the U.S.A. Most horses had low worm burdens, whereas a very small number were heavily infected. Ninety-seven per cent of the total strongyle counts were small strongyles. Strongylus species contributed just over 1%. Small numbers of large strongyles per horse were usual with T. serratus (mean 570), S. vulgaris (mean 330), and S. equinus (mean 330) the most numerous.(ABSTRACT TRUNCATED AT 250 WORDS)     

Species of Cloacina Linstow, 1898 (Nematoda: Strongyloidea) from the black-tailed wallaby, Wallabia bicolor (Desmarest, 1804) from eastern Australia

Species of Cloacina Linstow, 1898 (Nematoda: Strongyloidea) are reported and/or described from the stomach of the macropodid marsupial Wallabia bicolor (Desmarest, 1804) collected in eastern Australia. Nematodes were examined from 26 hosts collected in 3 states and the number of species of Cloacina in any one host was 2--7. The following species were encountered: C. wallabiae Johnston and Mawson, 1939, C. gallardi Johnston and Mawson, 1940, C. edwardsi Mawson, 1972 and C. cornuta (Davey and Wood, 1938) the last named constituting a new host record. The following new species are described: C. mawsonae sp. nov., C. papillata sp. nov., C. annulata sp. nov., C. castor sp. nov. and C. pollux sp. nov.     

Neorhabditostomum yeni n. g., n. sp. (Nematoda,Strongyloidea) from Muntiacus muntjak in Sabah,Malaysia

Neorhabditostomum yeni n. g., sp. is described from the intestine of the barking deer, Muntiacus muntjak, from Simatuoh, Sapulot, Sabah, Malaysia. It is distinguished from the nearest genera, namely Bourgelatoides and Rhabditostomum, in the subfamily Oesophagostominae by the presence of an elongate, unsegmented, oesophageal funnel, a single leaf crown, the separation of the oral collar by a wide groove from the cephalic vesicle, the position of the cervical papillae, the absence of filaments on the spicules and the absence of an evagination of the vulva. The significance of the arrangement of the cephalic papillae within the Stronglyloidea is discussed. ac]19860428     

Molecular separation of Oesophagostomum stephanostomum and Oesophagostomum bifurcum (Nematoda: Strongyloidea) from non-human primates.

The ITS-2 sequences for adult specimens of Oesophagostomum stephanostomum from the common chimpanzee and Oesophagostomum bifurcum from the Mona monkey were determined. For both species, the length and GC content of the ITS-2 sequences were 216 bp and 43%, respectively. While there was no unequivocal sequence difference among individual worms representing each of the two species, five (2.3%) interspecific nucleotide differences were detected. These differences were associated with the presence of unique restriction sites in the ITS-2 sequence of 0. stephanostomum for multiple endonucleases of diagnostic value for the differentiation of the two taxa by restriction analysis. Pairwise comparisons of the ITS-2 sequences of O. stephanostomum and O. bifurcum with published ITS-2 sequences for five different congeners indicated that these species from the subgenus Conoweberia are closely related, in accordance with previous morphological studies.     

The anterior glands of adult Necator americanus (Nematoda: Strongyloidea)—I Ultrastructural studies

The ultrastructure of the amphidial, oesophageal and excretory glands of N. americanus is described. There are two amphidial glands, and each is attached to a lateral hypodermal cord. Anteriorly the glands become associated with the amphidial sense organs. The amphidial glands synthesize complex secretion granules which appear to release their contents into the sense organ. Secretions thus pass over the amphidial cilia and exit via the amphidial pore. It is suggested that the secretory activity of these glands is under direct nervous control. There are three oesophageal glands, and each synthesizes dense secretion granules. The secretions of the oesophageal glands are released into the lumen of the oesophagus and into the buccal capsule. The two excretory glands are ventral in position and connected to the tubular excretory system. These glands synthesize secretion granules of varying density. Secretions from the excretory glands may exit via the excretory pore, or pass back into the tubular excretory system, or both.     

Relationships within theRugopharynx delta species complex (Nematoda: Strongyloidea) from Australian marsupials inferred from allozyme electrophoretic data

Relationships between the strongyloid nematodesRugopharynx delta, R. zeta, R. omega, R. longibursaris, R. mawsonae andR. sigma, all from macropodid marsupials, were investigated using allozyme data. The phylogenetic trees derived from the electrophoretic data set were congruent with those of the hosts and were consistent with the hypothesis that the species complex originated in pademelons of the genusThylogale and diversified in rock-wallabies (Petrogale spp.) and scrub wallabies of the subgenusNotamacropus. Host switching is evident only between closely related macropodid taxa.     

Strongylus asini (Nematoda, Strongyloidea): Genetic relationships with other strongylus species determined by ribosomal DNA

Genomic DNA was isolated from adult Strongylus asini collected from zebra. The second ribosomal transcribed spacer (ITS-2) was amplified and sequenced using polymerase chain reaction (PCR) based techniques. The DNA sequence was compared with previously published data for 3 related Strongylus species. A PCR-linked restriction fragment length polymorphism method allowed the 4 species to be differentiated unequivocally. The ITS-2 sequence of S. asini was found to be more similar to those of S. edentatus (87.1%) and S. equinus (95.3%) than to that of S. vulgaris (73.9%). This result confirms that S. asini and S. vulgaris represent separate species and supports the retention of the 4 species within 1 genus.     

Detection by allozyme electrophoresis of cryptic species of Hypodontus macropi (Nematoda: Strongyloidea) from macropodid marsupials.

Allozyme electrophoresis of 98 Hypodontus macropi from eight different species of hosts using 24 enzymes revealed a complex of at least six sibling species, with 15-50% fixed genetic differences between taxa. Except for the taxon parasitizing Macropus rufus/M. robustus, pairs of parasite taxa were, in each case, sympatric at each locality examined, thus supporting the conclusion that they represent valid species. The existence of a series of host-specific nematode taxa explains many of the inconsistencies noted previously in the host distribution of H. macropi. Comparison of parasite allozyme phenograms with host phylogeny suggests that four of the speciation events could be attributable to cospeciation and two to host switching. A clear case of host switching between M. rufus/M. robustus and M. fuliginosus was found.