Abstract
The new species Iotonchus lotilabiatus n. sp. from Bat Xat Nature reserve in Lao Cai Province, Vietnam is described and the molecular data (18S and 28S rDNA) are given. Females of the new species are characterized by large body size (L = 3.8-5.2 mm); barrel shaped buccal cavity of large size (41–54×70–89 µm) with dorsal tooth apex located 22 to 23.5% of buccal cavity length from its base; reproductive system didelphic-amphidelphic, vagina long, corresponding almost half of body width at the vulva with distinct parrefringens vaginae, sclerotized and triangulated pieces in optical section; tail long filiform, ventrally arcuate, with three small caudal glands in tandem and prominent terminal spinneret. Males with spicules 119 to 148 µm in length, and slender, slightly curved gubernaculum, 39 to 44 µm long and with 13 to 14 ventromedian supplements. The new species Iotonchus lotilabiatus n. sp. is closest to I. miamaensis (Khan and Araki, 2002), but differs by having larger size of body length and buccal cavity, lower position of dorsal tooth apex; longer female tail with lower c but higher c′ ratios and the presence of advulval cuticular structures.
Highlights
The genus Iotonchus was proposed by Cobb (1916) when he split the genus Mononchus (Bastian, 1865) into five subgenera Mononchus, Prionchulus, Mylonchulus, Iotonchus, Anatonchus, and ultimate raised in rank to genus level
In 1982, Jairajpuri and Khan proposed the new genus Jensenonchus based on the type species J. ovatus (Jensen and Mulvey, 1968) which was transferred from the genus Iotonchus
The genus Jensenonchus differs from the genus Iotonchus in having more anteriorly dorsal tooth position and a weak longitudinal ridge opposite to dorsal tooth, anteriorly gradually merging into the ventral wall (Jairajpuri and Khan, 1982)
Summary
Soil samples were collected randomly from a pristine forest inthe Bat Xat Nature Reserve, Lao Cai Province, Vietnam. Nematodes were extracted from soil samples using modified Baermann funnel technique (Southey, 1986). They were heat killed, fixed in 4% formaldehyde (for morphological observations) or in a DESS mixture (Yoder et al, 2006) (for molecular analyses), transferred to anhydrous glycerol (Seinhorst, 1962), and mounted on glass slides for microscopic observation. The newly obtained rDNA sequences were analysed using the BioEdit sequences avalaible in GenBank using the ClustelW aligment tool implemented in the MEGA 7 version 7.0 (Kumar et al, 2016). The final 18S and 28S rDNA datasets for phylogenetic study included sequences from the current study Iotonchus lotilabiatus sp. Maximum likelihood with T92+G substitution model for both, 18S and 28S data sets was used
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