A survey of the Pratylenchus species was conducted in crop fields of Central Japan to show the species composition, and a geographic border of distribution lying between Pratylenchus coffeae and its closely allied species (Pratylenchus sp.). Pratylenchus species were found in 47 soil samples from the fields of soybean, red bean, corn, taro, potato, barley, and upland rice. Identification of the species was solely conducted on the polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) bases in a partial region of ribosomal DNA. Five species of Pratylenchus were detected in this region. Pratylenchus penetrans was found most frequently from the crop fields examined (species composition rate: 72.3%), followed by Pratylenchus sp.(14.9%), P. neglectus (12.8%), P. coffeae (8.5%), and P. vulnus (4.3%). Species composition of Pratylenchus within the kind of crops is compared. Pratylenchus coffeae was detected from four sites in Tochigi, Saitama and Chiba Prefectures, and Pratylenchus sp. was found from seven sites in Tochigi and Saitama Prefectures: it is presumed that the geographic border of the two species lies between Tochigi and Saitama-Prefectures.

View full abstract

Host and temperature preference, male occurrence, and morphometrics of 39 isolates of Aphelenchus avenae were investigated. Of the 39 isolates, 33 were from 7 districts of Kyushu, 3 from Okinawa, and 2 from Ibaraki and 1 from Fukushima prefecture of Honshu. The host preferences were investigated on 4 species of fungi; Botrytis cinerea, Rhizoctonia solani AG-4, Fusarium oxysporum f. sp. melonis, and Pythium aphanidermatum growing on 1/5 strength PDA medium. The nematodes were incubated on respective fungus mat for 30 days at 25 and 30°C. Host fungi and temperatures gave rise to various levels of reproduction and male occurrence. The isolates were divided into 5 groups based on their reproductivity on their host fungi at the 2 temperature regimes. Most of the isolates of A. avenae propagated themselves at 25°C on B. cinerea and R. solani AG-4, whereas some isolates, especially from Okinawa and Kagoshima i.e. southern parts of Kyushu, preferred 30°C. The highest multiplication from the initial 10 females at 25°C, 30 days after inoculation on B. cinerea was 60, 850 given by Nagasaki isolate (NA3). The maximum multiplication 48, 420 at 30°C occurred on R. solani by Kagoshima isolate (KA3). The occurrence of males was very low in all isolates and it occurred only at 30°C. De MAN's value of body dimension were measured and showed no significant variations among the isolates. Besides, there were no relations between groupings by host preference and by body dimension.

View full abstract

A new Caenorhabditis species collected from fruiting bodies of Auricularia polytricha is described and illustrated. C. auriculariae n. sp. is characterized by the metarhabdion with a bifid flap-like tooth. The caudal papilla 8 bent dorsally and anteriorly bifid brim-like structure on the precloacal lip are also unique to C. auriculariae n. sp. These are considered to be autapomorphic characters for this new species. This new species has been obtained also from rotting parts of wood and maintained on bacterial plates of Asparagine-mannitol agar.

View full abstract

Iotonchium cateniforme n. sp. is described. This species possesses four adult forms; mycetophagous female, infective female, parasitic female, and male. The mycetophagous females inhabit in the stipes of fruiting bodies of Cortinarius subalboviolaceus and of two Cortinarius spp. Males and infective females were also obtained from these fruiting bodies. The parasitic females inhabit in haemocoel of the fungus gnat Exechia dorsalis. The mycetophagous female has a long uterus containing many eggs, being different from that of other previously described Iotonchium species.

View full abstract

Mycetophagous females of Iotonchium ungulatum inhabit in the knots produced on the gills of fruiting bodies of the oyster mushroom, Pleurotus ostreatus (1, 8), and are supposed to feed on hyphae forming knots. AIHARA (1) described the morphological characteristics of the nematode, but he did not describe its oesophagus in detail because of the overlapping ovary.
POINAR (4) noted that the mycetophagous females of I. californicum possess morphological features characteristic of Hexatylus species. He called this female “hexatyloid form”. In Hexatylus viviparus, the position of oesophagus and intestine had been the subject of controversy (2, 3, 6, 7), but he did not discuss the matter in “hexatyloid” females of I. californicum (4).
Some of our I. ungulatum specimens collected in Kyoto are appropriate for observing anterior alimentary tract of mycetophagous females. We describe the structure of this organ, and compare it with that of I. californicum and H. viviparus.

View full abstract