Isomermis bipapillatus n. sp. and Gastromermis mesostoma n. sp. (Mermithidae: Nematoda), parasites of Simulium japonicum (Simuliidae: Diptera) in Japan

Summary Two new species of the Mermithidae (Nematoda) are described from the Japanese blackfly Simulium japonicum Matsumura. They are the first representatives of Gastromermis and Isomermis from Japan. Gastromermis mesostoma n. sp. is characterized by a terminal or near terminal mouth, 6 hypodermal cords and the absence of cloacal or vulvar lips. Isomermis bipapillatus n. sp. is characterized by the small size of the spicules, their curved shape and by a pair of terminal hypodermal protuberances in the tail. This work was in part supported by a grant (No. 58570188) from the Japanese Ministry of Education, Science and Culture This work was in part supported by a grant (No. 58570188) from the Japanese Ministry of Education, Science and Culture     

Hydromermis osami n. sp. (Nematoda: Mermithidae) from chironomids eclosing from northern Minnesota waterways

Hydromermis osami n. sp. (Nematoda: Mermithidae) is described from the hemocoel of 2 species of Rheotanytarsus chironomid imagos eclosing from Lake Ozawindib and Gulsvig Landing in northern Minnesota during August 2002 and June and July 2006. The species is distinguished from the other 26 described members of the genus by the terminal mouth; oval, opaque, thick walled amphids, wider than long; acute posterior end; single spicule not bifurcated proximally; well-developed uterine and vulval limbs of the S-shaped vagina; absence of bursal sleeve; absence of nutrient vesicles in the trophosome; and an esophagus length over 40% of body length. Members of the new species emerge from the hosts as adults. The other described Hydromermis species, number of specimens, location, and known hosts are tabulated.     

Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) parasitizing terrestrial isopods (Isopoda: Oniscoidea)

Summary A new mermithid nematode, Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) was found parasitizing two terrestrial isopods (Isopoda: Oniscoidea) in California. The hosts, Armadillidium vulgare (Latr.) (a pillbug) and Porcellio scaber (Latr.) (a sowbug) represent the first cases of isopods attacked by mermithid nematodes. The genus Thaumamermis can be distinguished from all previously described mermithids by the extremely dimorphic spicules, one being short and broad and the other long and filiform. It has been discovered that the nematodes are infected with an iridiovirus which commonly destroys the isopod hosts. ac]19800917     

Strelkovimermis spiculatus n. sp. (Mermithidae: Nematoda) Parasitizing Aedes albifasciatus Mac. (Culicidae: Diptera) in Argentina

Strelkovimermis spiculatus n. sp. (Mermithidae: Nematoda), a parasite of the mosquito Aedes albifasciatus Mac. in Argentina, is described. Diagnostic characters of this species include a ventrally shifted mouth opening and spicules fused at the tips. The mermithid has been reared on Culex pipiens L. larvae in the laboratory.     

Anatomy of the Pre-Parasitic Stage of Hydromermis conophaga (Mermithidae: Nematoda)

The anatomy of the preparasitic juvenile of Hydromermis conopophaga (Mermithidae: Nematoda) has been examined with the light and electron microscope. The alimentary tract consisted of an onchiostylet, pharyngeal tube, stichosome, and intestine. Paired penetration glands were associated with the anterior half of the stichosome. A total of 16 sensory papillae were found in this stage. Certain features, such as the character of the stylet and the attachment of the pharynx to the intestine, show that the preparasitic juvenile more than any other stage in its life cycle closely resembles a free-living dorylaimoid nematode.     

Strelkovimermis rubtsovi n. sp. and Strelkovimermis ozawindibi n. sp. (Nematoda: Mermithidae) parasitizing chironomid (Insecta: Diptera) adults eclosing from northern Minnesota glacial lakes

Two new species of Strelkovimermis are described from chironomid imagoes eclosing from northern Minnesota glacial lakes. The 2 species are distinguished from the other 12 species in the genus by terminal mouths, rounded or nippled posterior ends, short buccal funnels, short terminal limbs of the S-shaped vagina, and presence of a bursal sleeve. Strelkovimermis rubtsovi n. sp. is distinguished from S. ozawindibi n. sp. by the presence of a dorsal protractor. Procladius (Psilotanypus) bellus (Loew) is the host of S. rubtsovi. The chironomid host of S. ozawindibi has not been determined. An artificial key is provided to distinguish the 14 species of the genus.     

Lanceimermis palustris n. sp. and Telomermis palustris n. sp. (Nematoda: Mermithidae) parasites of chironomid (Insecta: Diptera) adults from Lake Alice Bog in northern Minnesota

In the summer of 2003, chironomid imagoes eclosing from Lake Alice Bog in Minnesota yielded mermithid nematodes of 2 new species. Lanceimermis palustris n. sp. is distinguished from the other 14 species of the genus by the subventral mouth position, thinness of the hook-shaped spicule, body index, and structure of the male tail muscles. Telomermis palustris n. sp. is distinguished from the only other species of the genus by the structure of the amphids, body length, maximum body width, length of the esophagus, and the presence of a minute larval terminal horn. Lanceimermis palustris n. sp. hosts were Chironomus maturus Johannsen and T. palustris n. sp. hosts were Tanytarsus mendax Kieffer, Paratanytarsus nr. dissimilis n. sp., and Micropsectra polita (Malloch). In both mermithid species, the percent of mermithid males per host increased with the intensity of the infection.     

Nematode (Nematoda: Mermithidae) and hairworm (Nematomorpha: Chordodidae) parasites in Early Cretaceous amber

The present report describes a mermithid nematode (Nematoda: Mermithidae) and a gordiid hairworm (Nematomorpha: Chordodidae) from Early Cretaceous Burmese amber dated at 100-110 million years. The mermithid, Cretacimermis protus sp. n., is emerging from a biting midge (Diptera: Ceratopogonidae) while the hairworm, Cretachordodes burmitis, gen. n., sp. n. had already emerged from its host. These rare specimens represent the first fossil mermithid parasite of a ceratopogonid midge and second oldest described nematode and the earliest known and only Mesozoic fossil of the phylum Nematomorpha. A list of previously described fossil mermithids is included.     

Strelkovimermis papillosus n. sp. (Nematoda: Mermithidae), a parasite of chironomid (Insecta: Diptera) adults from the headwaters of the Mississippi River in northern Minnesota

On 18 August 2002, chironomid imagoes of Rheotanytarsus sp. emerged from the upper Mississippi River in Minnesota and yielded distinctive mermithid nematodes of a new mermithid species. Strelkovimermis papillosus n. sp. is distinguished from the other 14 species of the genus by the presence of unusually large cephalic papillae encircling the mouth and forming a rosette with the mouth in the center and by the absence of a fixator muscle in the males. Additionally, both sexes have very acute posterior ends, long amphids, and a long stoma. Strelkovimermis is revised by eliminating nondiscriminating parameters and accommodating the 15 known species. Intrageneric characteristics useful in separating species of Strelkovimermis are listed. Intensity of infection and intensity of infection versus sex were determined from 41 hosts. Where known, the hosts and geographical distribution are given for all 15 Strelkovimermis species.     

Parasitism of Kenyan Mosquito Larvae (Diptera: Culicidae) by Romanomermis culicivorax (Nematoda: Mermithidae)

The ability of Romanomermis culicivorax to infect, develop, and emerge from Kenyan mosquito hosts was evaluated in the laboratory. Host species tested were Aedes aegypti, Ae. dentatus, Ae. hirsutus, Anopheles arabiensis, An. coustani, An. funestus, An. gambiae, An. pharoensis, Culex duttoni, Cu. ethiopicus, Cu. poicilipes, Cu. quinquefasciatus, Cu. tigripes, Cu. univittatus, Coquillettidia metallica, Mansonia africana, Ma. uniformis, Mimomyia splendens, Mi. uniformis, Toxorhyncites brevipalpis, and Uranotaenia balfouri. R. culicivorax penetrated all the host species tested and developed and emerged from most of the hosts. Both penetration and some development, but not nematode emergence, were observed from all instars of Ma. uniformis. T. brevipalpis exhibited signs of resistance in the form of melanization of R. culicivorax within 48 hours of infection in all four instar stages. Nematode melanization, especially in older hosts, was observed in Ae. dentatus, Ae. hirsutus, Cu. duttoni, Cu. tigripes, and Mi. splendens. When melanization occurred, the melanized carcass of the nematode was passed on from instar to instar. The implications for field release of R. culicivorax in Kenya are still good, especially in habitats where different mosquito species occupy the same niche at different times, which would allow for nematode recycling.     

Electron Microscope Observations of the Melanocyte of the Human Epidermis

Using standard osmium fixation and methacrylate embedding techniques, a study has been made of the melanocyte of human biopsy skin removed under general and local anaesthesia. Melanogenesis was easily observable in the melanocytes, but immature pigment granules were rarely seen in the Malpighian cells. The passage of melanin from melanocyte to Malpighian cell—cytocrine secretion—is thought to have been observed. Phagocytes near the dermal-epidermal junction seem to have their pigment granules in vacuoles, rather than surrounded directly by the cytoplasmic matrix as in the melanocytes. This, together with the failure to observe "effete" melanocytes, prompts the suggestion that the phagocytes are melanocytes which have migrated from the epidermis into the dermis. A melanin granule is shown with alternating dark and lighter transverse striations, concerning which structure little can at present be said.     

Diximermis peterseni (Nematoda: Mermithidae): a potential biocontrol agent of Anopheles mosquito larvae

The mermithid nematode Diximermis peterseni was successfully transferred and established in an artificial pond and then in a natural pond. The exposure in the artificial pond initially produced 92% parasitism in introduced larvae of Anopheles quadrimaculatus; then parasite activity gradually decreased and disappeared. However, it reappeared 8 months after the introduction and has been observed in introduced hosts during each of the 40 months since. The release of 2300 Anopheles (85–90% infected) into a natural pond (January–March 1971) produced 12–100% parasitism during the 8-month period between September 1971, and March 1972. Furthermore, during the same months in 1972–1973, an average of 88% of the Anopheles in the pond were parasitized. These data indicate that D. peterseni can be easily established and will produce significant levels of parasitism despite long periods of dry weather and low host densities.