Fine Structure of Cephalic Sense Organs in Heterodera glycines Males

Cephalic sense organs of Heterodera glycines males were examined in detail by electron microscopy. Each amphid basically consists of an amphidial gland, a nerve bundle, and an amphidial duct. The amphidial gland consists of a microvillous region, and laterally is closely associated with a large secretory cell. The nerve bundle penetrates the microvillous region, and further anteriorly individual nerve processes (dendrites) separate from one another, thus forming a sensilla pouch which is enveloped by the microvillous region of the gland. Anterior to the pouch, the cilia-like dendrites converge as they enter and eventually terminate in the amphidial duct. Heterodera glvcines males have the innervation basis for a full complement of sixteen papillae, although surface manifestations are present for only six minute inner labial papillae. In addition, four outer labial and four cephalic receptors terminate beneath the surface, and another two dendrite pairs end further posteriorly beneath the basal plate of the cephalic framework. Papillary receptors which terminate beneath the surface are probably mechanoreceptive, whereas inner labial papillae have pore-like openings to the exterior and may be chemoreceptive. Amphids and papillae of H. glycines are fundamentally similar to those of Meloidogyne incognita, although certain striking differences exist.     

Ultrastructure of the anterior sense organs of adult Gastromermis boophthorae (Nematoda: Mermithidae)

The amphids of adult Gastromermis boophthorae exhibit an organization unlike any previously reported. Each amphid consists of a distal cuticular channel which opens to the exterior, and a proximal amphidial gland. The cuticular channel is double and 15–18 cilia are held in a tight bundle by the inner channel. The amphidial gland contains an extensive reticulum, and the nerve axons which give rise to the amphidial cilia are arranged around the outside of the gland; anteriorly these axons are characteristically flattened. A granular secretion is produced by the amphidial gland and passes via the reticulum to the double cuticular channel, thus bathing the ciliary bundle. The ultrastructure of the amphids is discussed in relation to functional considerations.     

Scanning Electron Microscope Studies of Steinernema anomali Kozodoi, 1984

This paper presents SEM micrographs of portions of the male, female, and infective-stage juvenile of Steinernema anomali. Included are micrographs of the cephalic and caudal region, spicules, and gubernaculum of the male, the cephalic and vulval region of the female, and the cephalic region of the infective-stage juvenile. Males have six labial and four prominent cephalic papillae and small amphids. There are 11-14 pairs and one single genital papillae; of these, 6-9 pairs are preanal and subventral, one pair preanal, lateral, one pair adanal, and three pairs postanal. Spicules have a short head, a long blade, and a reduced shaft. The distal end is enlarged and bears a dorsal aperture. Gubernaculum much shorter than spicules; cuneus of gubernaculum short and bifurcate anteriorly. Females have six labial and four cephalic papillae and small amphids. Vulva with a thickened posterior lip. Infective juveniles have a smooth head, prominent amphids, and four cephalic papillae. Labial papillae, if present, are not evident.     

Addendum to the Morphology of Steinernema scapterisci

This paper provides additional information on the morphology of Steinernema scapterisci. For females, the amphids are shown for the first time, and clearer scanning electron microscope (SEM) photographs of the six labial and four cephalic papillae are presented. For males, six labial and four cephalic papillae, one or two pairs of additional genital papillae, and the death shape are shown. For infective juveniles, six labial and four cephalic papillae and an elevated oral disc are shown.     

Scanning Electron Microscopy of Second-Stage Juvenile Cephalic Morphology in Heterodera glycines Races

Scanning electron microscopy (SEM) was used to compare juvenile cephalic morphology of the five described races of Heterodera glycines. Races 1, 2, 3, and 4 were obtained in the United States and race 5 was obtained from Japan. Differences in the gross morphology o f labial discs; ventral, dorsal and lateral lips; amphidial apertures; and fissures on the labial disc o f some specimens were observed. There was considerable interracial and intraracial variation which precluded separation o f juveniles of H. glycines races by SEM.     

Chemical reproductive traits of diploid Bombus terrestris males: Consequences on bumblebee conservation

The current bumblebee decline leads to inbreeding in populations that fosters a loss of allelic diversity and diploid male production. As diploid males are viable and their offspring are sterile, bumblebee populations can quickly fall in a vortex of extinction. In this article, we investigate for the first time a potential premating mechanism through a major chemical reproductive trait (male cephalic labial gland secretions) that could prevent monandrous virgin queens from mating with diploid males. We focus our study on the cephalic labial gland secretions of diploid and haploid males of Bombus terrestris (L.). Contrary to initial expectations, our results do not show any significant differentiation of cephalic labial gland secretions between diploid and haploid specimens. Queens seem therefore to be unable to avoid mating with diploid males based on their compositions of cephalic labial gland secretions. This suggests that the vortex of extinction of diploid males could not be stopped through premating avoidance based on the cephalic labial gland secretions but other mechanisms could avoid mating between diploid males and queens.     

Scanning electron microscopy of the labia of Baylisascaris procyonis (Nematoda)

The labial organization of adult Baylisascaris procyonis was studied by scanning electron microscopy, and found to be similar for males and females. The apical part of each lip was smooth, and the basal part reticulated. The dorsal lip possessed two dorsolateral double papillae and two internal labial papillae; the two subventral lips each had one ventrolateral double and one externolateral papilla, two internal labial papillae, and an amphid. The small papilla of each double set was dome-shaped and smooth, whereas the large papilla was broad and had a prominent central pore. The externolateral papillae had raised, highly sculptured surfaces with numerous slits and creases present. Amphids resembled those of previously studied nematodes. The internal labial papillae consisted of pits. Denticles arose as a single row from the apical edge of the inner labial surface, were usually evenly spaced, and pyramidal or conoidal in shape. They were typically unicuspid, but bicuspid denticles were occasionally seen. Denticle shape and size varied between specimens and on each specimen. A pit was seen in the cuticle in the central region of the denticular row of all lips. Several of these findings represent new information concerning ascaridoid nematodes.     

Morphological Comparison of Second-Stage Juveniles of Six Populations of Meloidogyne hapla by SEM

External morphology of second-stage juveniles of six populations of Meloidogyne hapla, hclonging to two cytological races (A and B), and one population each of M. arenaria, M. incognita, and M. javanica was compared by scanning electron microscopy (SEM). Race A of M. hapla included three facultatively parthenogenetic populations with haploid chromosome numbers of 15. 16, and 17; race B consisted of three mitotically parthenogenetic populations with somalic chromosome numhers of 45, 45, and 48. The mitotically parthenogenetic populations of M. arenaria, M. incognita, and M. javanica had 54, 41-43, and 44 chromosomes, respectively. Observations were made on head structures, lateral field, excretory pore, anal opening, and tail. Head morphology, including shape and proportion of labial disc and lips, expression of labial and cephalic sensilla, and markings on head region, was distinctly different for each species. M. hapla populations of race A were distinct from each other but showed much intrapopulatiou variation in head morphology. Populations of race B were different from those of race A and were very stable and quite similar in head morphology. Considerable inter- and intrapopulatiou variation made the structure of the lateral field, excretory pore, anal opening, and tail of little value in distinguishing species or populations. The results are discussed in relation to earlier SEM observations on the genus Helerodera.     

A new genus of Cystidicolid nematode from the stomach of Galaxias maculatus (Osmeriformes: Galaxiidae) in Patagonia (Argentina)

During a parasitological survey of Galaxias maculatus (Jenyns) from Patagonian Andean Lakes, specimens of a new species of nematode were collected from the stomach of fish and studied by light and scanning electron microscopy. This species is described as the only member of a newly proposed genus of Cystidicolidae by having oral opening dorsoventrally elongated, 2 lateral pseudolabia, 4 cephalic papillae, stoma (vestibule) elongated, esophagus divided into anterior muscular and posterior glandular sections, and caudal alae in males. Placonema n. gen. (Habronematoidea, Cystidicolidae) is characterized by the combination of the following features: oral opening dorsoventrally elongated demarcated by 4 sclerotized plates and 2 well-developed pseudolabia projected to the buccal cavity, each pseudolabium with conspicuous, conical, anterior protuberances. Four cephalic papillae and deirids simple. Male with caudal alae, area rugosa absent, 4 pairs of preanal papillae, unpaired papilla present on anterior cloacal lip, and 6 pairs of postanal papillae. Larvigerous eggs without filaments. Placonema pataguense n. gen. n. sp. infects the stomach of G. maculatus from Lake Patagua (Patagonia, Argentina) and is the first species of Cystidicolidae described from G. maculatus.     

Observations on the Morphology of the Pine Wood Nematode, Bursaphelenchus xylophilus

Scans of slash pine wood chips infested with pine wood nematodes showed coiled aggregates of 5-10 nematodes in the axial resin canals, and 1-2 nematodes folded in the radial resin canals. Observations of the pine wood nematode by SEM showed the head to be offset with six labial lobes. A smaller circle of six inner lobes surrounded the stoma. A single labial sensillum was observed on each of the two subventral and two subdorsal lobes. The two opposite lobes, without sensilla, bore a pore-like amphid. The female vulva flap was observed to be a pouch. In addition to two pairs of copulatory papillae previously described for the male, three additional papillae were observed: an additional post-anal pair, and a single papilla anterior to the cloaca. Spicules were fused ventrally. Distal spicule ends terminated in two fused half discs. Caudal alae were angular at the tail terminus, but culed inward at the corners to appear oval. Lateral fields had four lateral striations.     

Hirschmanniella pomponiensis n. sp. (Nemata: Pratylenchidae), Parasitic on Bulrush,Scirpus robustus Pursh

A new species of Hirschmanniella was found in bulrush roots; LM and SEM morphological studies revealed that it is distinct from other species in the genus. Therefore, it is designated Hirschmanniella pomponiensis n. sp. Six lips are fused to form a hexagonal labial plate, six inner sensilla encircle the stoma opening, and four cephalic sensilla open in the corners of subdorsal and subventral lips. Cephalic lip region consists of six or seven annuli. The female has incomplete areolation in the lateral field, the intestine overlaps the rectum, the tail tip is pointed and without annulation.     

Ultrastructural observations on the sensory papillae of juvenile and adult Gorgoderina vitelliloba (Trematoda: Gorgoderidae)

Hoole D. and Mitchell J.B. 1981. Ultrastructural observations on the sensory papillae of juvenile and adult Gorgoderina vitelliloba (Trematoda : Gorgoderidae). International Journal for Parasitology11: 411–417. Ultrastructural observations have been made on the juvenile and adult stages of Gorgoderina vitelliloba from Rana temporaria. Four types of sensory papillae occur; button, rosette, ciliated and domed. Button papillae, which contain a ciliary-rootlet but lack a cilium, occur on the oral sucker, dorsal preacetabular surface and the lateral margins of the fluke. Scanning electron microscopical observations reveal that the tegumental protuberances of the papilla are transformed from a spiked or conical appearance in juvenile flukes to a rounded form in adult flukes. Rosette papillae, which also contain a rootlet, occur on the lip of the ventral sucker of both juvenile and adult flukes. Ciliated papillae only occur on the oral sucker of juvenile flukes. Domed papillae, which contain a large area of electron-dense material, occur on the internal surface of the ventral sucker of both juvenile and adult flukes. The functions of papillae and their possible role in the migration of the parasite are discussed.     

Discopersicus n. gen., a New Member of the Family Tylenchidae ?rley, 1880 with Detailed SEM Study on Two Known Species of the Genus Discotylenchus Siddiqi, 1980 (Nematoda; Tylenchidae) from Iran

Discopersicus iranicus n. gen., n. comb., previously described from Iran as a new species under the genus Discotylenchus, is illustrated using light microscope and scanning electron microscope (SEM) observations and further studied using molecular characters. SEM studies revealed the newly proposed genus has oblique amphidial apertures on the lateral sides of the lip region. SEM images are also provided for two species of Discotylenchus, namely D. discretus and D. brevicaudatus, as the first SEM study of the genus. These results confirmed longitudinal amphidial aperture type on lateral sides of the lip region in genus Discotylenchus, as noted by Siddiqi while erecting the genus with D. discretus as the type species. Molecular phylogenetic analyses using partial small subunit (SSU) and large subunit (LSU) rDNA sequences revealed the affinity of the genus Discopersicus n. gen. with members of the subfamily Boleodorinae, as supported by morphological characters (mainly, the oblique amphidial opening).     

Fine Structure of the Esophagus of Males of Sarisodera hydrophila (Heteroderoidea)

The fine structure of the esophagus, including procorpus, metacorpus, isthmus, gland lobe, and esophago-intestinal junction, is examined in males of Sarisodera hydrophila. A cuticle-lined lumen extends most of the length of the esophagus, broadens to form a pump chamber in the metacorpus, and posteriorly is continuous with junctional complexes among four esophago-intestinal cells. These four cells are partially enveloped by the gland lobe which basically consists of three gland cells, one dorsal and two subventral. Each gland cell has an anterior process which opens into the lumen of the esophagus through a cuticle-lined duct. The dorsal gland joins the lumen in the anterior portion of the procorpus, whereas ducts of the subventral glands terminate at the base of the metacorpus pump chamber. The subventral glands are predominant in the posterior portion of the gland lobe and are partially ensheathed by a narrow portion of the dorsal gland which extends to within 5 μm of the posterior terminus of the gland lobe. Contents of the dorsal gland include primarily electron dense granules, although rough endoplasmic reticulum (RER) is predominant posteriorly. Secretory granules within the subventral glands vary in morphology and are evenly distributed throughout the two ceils among other organelles, including RER and a large Golgi apparatus. Innervation of the esophagus includes nerve processes which originate from several perikaryons (cell bodies) located in the anterior portion of the gland lobe. The esophagus of males of S. hydrophila is compared with that of other Heteroderoidea, Heterodera glycines and Meloidogyne incognita.     

<Emphasis Type="Italic">Hexamermis popilliae</Emphasis> n. sp. (Nematoda: Mermithidae) parasitizing the Japanese beetle <Emphasis Type="Italic">Popillia japonica</Emphasis> Newman (Coleoptera: Scarabaeidae) in Italy

A new species of mermithid nematode, Hexamermis popilliae n. sp. (Nematoda: Mermithidae) is described from the Japanese beetle Popillia japonica Newman in Italy, an area of new introduction for this invasive pest. The combination of the following characters separates H. popilliae from other members of the genus Hexamermis Steiner, 1924: adult head obtuse; amphidial pouches slightly posterior to lateral head papillae in female but adjacent to lateral head papillae in males; amphidial openings large, well developed; amphidial pouches elliptical in females and oblong in males; cuticular vulvar cone well developed, vulvar lips greatly reduced or lacking, vagina curved at tip where meeting uteri, without reverse bend (not S-shaped), spicules slightly curved, with a slight bend in the basal portion, approximately equal to body width at cloaca. This is the first record of a species of Hexamermis parasitizing the Japanese beetle Popillia japonica. The only previous mention of mermithid nematodes from P. japonica was an undescribed species of Psammomermis in North America. Hexamermis popilliae will be evaluated as a potential biological control agent in an integrated control program of the Japanese beetle in Italy.     

Pratylenchus australis n. sp. and Eutylenchus fueguensis n. sp. (Nematoda: Tylenchina) from southern Chile

Two new species of nematodes from southern Chile are described and illustrated. Pratylenchus australis n. sp. is distinguished by its heavy cephalic sclerotization, smooth tail terminus, lack of spermatheca, and absence of males. Eutylenchus fueguensis n. sp. differs from other Eutylenchus spp. by the long female stylet (31 [28-32] μm), strongly sclerotized excretory duct opening posterior to nerve ring, and broadly rounded caudal alae of males.     

Pararotylenchus n. gen. (Pararotylenchinae n. subfam., Hoplolaimidae) with Six New Species and Two New Combinations

A new subfamily, Pararotylenchinae, (Hoplolaimidae) is described. It includes a single genus, Pararotylenchus n. gen., six new species, attd two new combinations, Pararotylenchus (syn. Tylenchorhynchus) brevicaudatus (Hopper, 1959) n. comb. and Pararotylenchus (syn. Rotylenchus) pint (Mamiya, 1968) n. comb. Pararotylenchinae is similar to certain other Hoplolaimidae, such as Rotylenchinae, with respect to most characters including the short tail, the position of the phasmids near the anus, and the relatively great distance of the dorsal gland orifice from the base of the stylet knobs. The lip region, as observed with the scanning electron microscope, conforms to the basic pattern for Hoplolaimidae. The labial disc is round with slit-like amphidial openings at the lateral sides of the periphery of the disc. The distinctive anterior-most lip annule is segmented into six sectors. Unlike other Hoplolaimidae, however, the esophageal glands of Pararotylenchinae form a basal bulb similar to that of Tylenchorhynchidae; other characters do not resemble Tylencborhynchidae. Specimens of Pararotylenchus have been recovered only from cool regions at high elevations and Pacific coastal areas in the Western United States, Japan, and Korea.     

Stage-specific Differences in Lectin Binding to the Surface of Anguina tritici and Meloidogyne incognita

The occurrence and distribution of several lectin binding sites on the outer surfaces of eggs, preparasitic second-stage juveniles (J2), parasitic second-stage juveniles (PJ2), females, and males of two tylenchid nematodes, Anguina tritici and Meloidogyne incognita race 3, were compared. In both species, a greater variety of lectins bound to the eggs than to other life stages; lectin binding to eggs was also more intense than it was to other life stages. Species-specific differences also occurred. More lectins bound to the amphids or amphidial secretions of M. incognita J2 than to the amphids or amphidial secretions of A. tritici J2. Lectins also bound to the amphids or amphidial secretions of adult male and female A. tritici, but binding to the cuticle occurred only at the head and tail and was not consistent in all specimens. Canavalia ensiformis and Ulex europaeus lectins bound specifically to the outer cuticle of M. incognita. Several other lectins bound nonspecifically. Oxidation of the cuticle with periodate under mild conditions, as well as pretreatment of the nematodes with lipase, markedly increased the binding of lectins to the cuticle of A. tritici J2 but not, in most cases, to M. incognita J2 or eggs of either species.