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.     

Fine Structure of Cephalic Sense Organs in Meloidogyne incognita Males

Amphids, and the cephalic and labial papillae of Meloidogyne incognita males were examined in detail by electron microscopy. Each amphid basically consists of an amphidial gland, a nerve bundle and an amphidial duct. The gland is a broad microvillous organ with a narrow anterior process, which is closely associated with the amphidial duct. A posterior process of the gland contains secretory organelles and proceeds along the esophagus with the lateral cephalic nerve bundle. The nerve bundle penetrates the broad portion of the gland and, subsequently, individual nerve processes (dendrites) separate from one another, thus forming the sensilla pouch which is enveloped by the gland. Anterior to the pouch, the dendrites converge as they enter and eventually terminate in the amphidial duct. The external opening of the duct is a broad slit which separates the cheek, the outermost part of the lateral lip, from the remainder of the lip region. M. incognita males have six inner labial papillae and four outer cephalic papillae which are each innervated by two and one cilia, respectively. In labial papillae, the cilia appear to terminate at the base of a pore opening, whereas in cephalic papillae each cilium terminates beneath the labial cuticle.     

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.     

Divisispiculimermis mirus n. gen., n. sp. (Mermithidae: Nematoda) Parasitizing Midges in Córdoba,Argentina

Divisispiculimermis mirus n. gen., n. sp., a mermithid parasitizing larvae of Chironomus sp. in the Cajón o Grande Stream, Córdoba, Argentina, is described. The new genus differs from all other mermithid genera in having paired spicules which are separated and divided into proximal and distal sectors. The other diagnostic characters of the genus are medium size, nematodes with the cuticle appearing smooth (lacking cross fibers under the light microscope); head separated from the rest of the body by a slight constriction at the level of the amphids, six cephalic papillae, mouth papillae absent, mouth opening posterior to level of cephalic papillae; six hypodermal chords at midbody; weakly S-shaped vagina; postparasitic juvenile with a tail appendage.     

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.     

Teratological Development in the Cephalic Anatomy of the Nematode Romanomermis culicivorax

Adults of Romanomermis culicivorax obtained from mass cultures were examined by scanning and transmission electron microscopy to determine the organization of their anterior sense organs. The normal pattern apparently consists of two lateral amphids plus six cephalic papillae. Lateral cephalic papillae contain two sense organs, each with a cuticular pore, while subdorsal and subventral papillae have three sense organs, each with a cuticular pore. About 30% of females and 80% of males examined showed aberrant developments in these sense organs. Both cuticle and underlying cells (hypodermis and neurons) are affected; some sense organs are absent while others are incompletely formed. Few aberrant worms were found in a smaller collection of worms reared in lower population densities. Perhaps aberrant forms are examples of teratological development resulting from, or promoted by, conditions used for mass rearing of biological control agents.     

Morphological Differences Between Radopholus citrophilus and R. similis

SEM observations of the external morphology of populations of Radopholus citrophilus and R. similis revealed several diagnostic differences. The cloaco-spicular orifice on males of R. citrophilus had three to seven genital papillae (anterior hypoptygmata), whereas males of R. similis were either smooth or had one or two shorter genital papillae (anterior hypoptygmata). Females of R. citrophilus had four annules in the region of the vulval opening, but R. similis had five annules in the same region. The labial disc and lateral lips appeared to be of diagnostic significance, but these areas were more susceptible to artifacts due to fixation. An unknown population of Radopholus from Puerto Rico with a chromosome number of n = 4 was morphologically similar to R. similis. These morphological differences provide additional support that R. citrophilus and R. similis are distinct species.     

<Emphasis Type="Italic">Amphibiophilus mooiensis</Emphasis> n. sp. (Nematoda: Amphibiophilidae), a parasite of <Emphasis Type="Italic">Amietia delalandii</Emphasis> (Duméril &amp; Bibron) (Amphibia: Pyxicephalidae) from South Africa

Four species of the genus Amphibiophilus Skrjabin, 1916 from pyxycephalid frogs in southern and central Africa are currently recognised as valid. Several specimens of Amphibiophilus were found in material from the common river frog, Amietia delalandii (Duméril & Bibron) (Amphibia: Pyxicephalidae), collected in Potchefstroom (North-West Province, South Africa). These specimens clearly differ from all previously known species by the shape of the distal end of the spicule, the shape of the gubernaculum and the structure of the synlophe. They are, thus, considered as a new species, Amphibiophilus mooiensis. As all other species in the family Amphibiophilidae Durette-Desset & Chabaud, 1981, A. mooiensis n. sp. possesses a number of archaic characters, such as a buccal capsule with a well-developed dorsal oesophageal tooth, six inner labial papillae, six outer labial papillae and four cephalic papillae. Molecular data (cox1 and ITS-28S rDNA sequences) are provided and host and geographical specificity are discussed.     

Localization of Cuticular Binding Sites of Concanavalin A on Caenorhabditis elegans and Meloidogyne incognita

Utilizing a Concanavalin A (Con A)-hemocyanin conjugate, the majority of cuticular Con A binding sites were shown to be localized on the head region of Caenorhabclitis elegans and Meloidogyne incognita. Secretions which apparently emanated from the amphids and inner labial papillae did not label.     

Description of Sclerorhabditis miniata n. sp. and First Description of Male of Diploscapter coronatus Cobb, 1913 (Nematoda: Rhabditidae)

A population of Sclerorhabditis miniata n. sp. is described and illustrated from Poonch district of Jammu and Kashmir State, India. The new species is characterized by small body size, with an annulated cuticle, offset labial region, crown shaped, strongly sclerotized lips, thin lateral lips, membranous, stegostom without glottoid apparatus, cheilostom rod shaped, sclerotized, spicules free, strong and thick, gubernaculum simple, bent proximally, bursa open, peloderan with seven pairs of bursal papillae in 1+1/1+1+2+1 pattern. The males of Diploscapter coronatus are described for the first time. They are usually smaller than the females and have labial region similar to females. Spicules separate, with a small dorsal velum, gubernaculum simple, almost straight, bursa open, pseudopeloderan with seven pairs of bursal papillae in 1+1/1+2+1+1 pattern.     

Stephanofilaria thelazioides n. sp. (Nematoda: Filariidae) from a hippopotamus and its affinities with the species parasitic in the African black rhinoceros

Stephanofilaria thelazioides n. sp. (Filarioidea: Filariidae: Stephanofilariinae) is described from a hippopotamus Hippopotamus amphibius. This nematode is close to S. dinniki Round, 1964, a parasite of the black rhinoceros Diceros bicornis in Africa, but differs from it in the number of cuticular spines surrounding the mouth, the arrangement of the cloacal papillae and the measurements of the spicules, gubernaculum and microfilariae. Species of the genus Stephanofilaria possess spines on the head which have been derived by modification of the sensory papillae. S. thelazioides is the most primitive species of the genus and has the least modified arrangement of these papillae, with six bifid internal labial spines, four bifid external labial spines and four cephalic papillae. The genus appears to have diversified in various mammals which have in common a thick skin, such as rhinoceroses, elephants, buffaloes and now the hippopotamus. It appears to have become adapted secondarily to domestic bovines, initially in Asia and subsequently in North America.     

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.     

Pseudascarophis brasiliensis sp. nov. (Nematoda: Cystidicolidae) parasitic in the Bermuda chub Kyphosus sectatrix (Perciformes: Kyphosidae) from southeastern Brazil

A new species of Pseudascarophis (Nematoda: Cystidicolidae) found in the stomach of Kyphosus sectatrix (Linnaeus) (Kyphosidae), off Rio de Janeiro, Brazil, is described. The new species can be differentiated from the other congeners by the presence of lateral alae, distinct but inconspicuous cephalic papillae at the anterior end, three pairs of precloacal and one pair of adcloacal papillae in males, egg morphology and morphometry of glandular oesophagus and spicules. Pseudascarophis tropica is transferred to Ascarophis as Ascarophis tropica (Solov''eva) comb. n. due to its ambiguous diagnosis.     

Redescription of Robustodorus megadorus with Molecular Characterization and Analysis of Its Phylogenetic Position within the Family Aphelenchoididae

Based on a new record of the rare species Robustodorus megadorus from Utah, the generic diagnosis was amended to include the following characters: a labial disc surrounded by six pore-like sensilla; the absence of a cephalic disc; a lobed cephalic region devoid of annulation; a hexagonal inner cuticular structure of the pouch surrounding the stylet cone; large stylet knobs, rounded in outline and somewhat flattened on their lateral margins; a large spermatheca with an occluded lumen and lacking sperm; the excretory pore located between the median bulb and nerve ring. The stylet orifice consists of an open, ventral, elongate slit or groove. These characters distinguish the genus from the closely related genus Aphelenchoides. A lectotype and paralectotypes were designated. Results of phylogenetic analyses of the 18S and D2-D3 of 28S rRNA gene sequences revealed that R. megadorus occupies a basal position within one of the two main clades of the subfamily Aphelenchoidinae and shares close relationships with a species group of the genus Aphelenchoides that includes A. blastophthorus, A. fragariae, A. saprophilus, A. xylocopae, and A. subtenuis. Several specimens in our collection of R. megadorus were infected with Pasteuria sp. as were some of the paralectotypes.     

Description and Bionomics of Mesomermis camdenensis n. sp. (Mermithidae), a Parasite of Black Flies (Simuliidae)

Mesomermis camdenensis n. sp. is described from larvae of Simulium tuberosum (lundstroem) collected in Camden Valley Creek, Washington County, New York. This species possesses a barrel-shaped vagina, vulval flap. two short separate spicules, terminal mouth, six longitudinal chords, six cephalic papillae, large sexually dimorpbic anaphids, an esophagns of uniform width which extends for less than one-third of the body length, and a cone-shaped tail directed ventrally without appendage. Juveniles also are described and illustrated.A detailed morphological comparison with the mermithid M. flumenalis Welch is presented. The most pronounced morphological differences between these species are in the shape of the vulva, juvenile tail, and infective stage. Cross-mating trials support the integrity of the new species.The life cycle of M. camdenensis is closely synchronized with that of its primary host, S. tuberosum larvae. Infected S. tuberosum larvae were first collected in May. Emergence of postparasites from late instars took place from mid-June through mid-October. Sampling data indicate a lower susceptibility to infection among S. venuslum Say larvae.     

Description of Distorhabditis poonchiana n. gen., n. sp. (Nematoda: Rhabditidae) from Jammu and Kashmir,India

Distorhabditis poonchiana n. gen., n. sp. from humus in Jammu and Kashmir, India, is described and illustrated. The new genus is characterized by a small body; slightly setoff labial region; long tubular gymnostom; prominently cuticularized cheilostom; absence of glottoid apparatus; monoprodelphic reproductive system; vulva (V) = 81 to 84; spicules with trifurcated distal ends, simple gubernaculum, peloderan bursa with eight pairs of bursal papillae arranged in 1 + 1 + 1 + 2 + 1 + 2 arrangement.     

Two new genera of nematode (Oxyurida,Hystrignathidae) parasites of Passalidae (Coleoptera) from the Democratic Republic of Congo

Two new genera and species parasitizing passalid beetles from the Democratic Republic of Congo are described. Kongonema meyeri gen. n. sp. n. is characterized by having females with the cervical cuticle unarmed, first cephalic annule cone-like and truncate, sub-cylindrical procorpus and genital tract didelphic-amphidelphic. The males of Kongonema meyeri gen. n. sp. n. have the procorpus sub-cylindrical, the dorsal cuticle of the tail end thickened, a single large, median mammiform pre-cloacal papilla and a pair of small, pre-cloacal, sub-lateral papillae at a short distance before the level of the cloaca. Lubanema decraemerae gen. n. sp. n. is characterized by the body markedly fusiform, cuticle unarmed and strongly annulated, procorpus sub-cylindrical, isthmus as a constriction between procorpus and basal bulb, genital tract monodelphic-prodelphic and the posterior end rounded with a very short tail appendage.