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Background: Nematodes of the genus Heterorhabditis are important biocontrol agents as they form a lethal combination with their symbiotic Photorhabdus bacteria against agricultural insect pests. This study describes a new species of Heterorhabditis. Methods: Six Heterorhabditis nematode populations were recovered from agricultural soils in Jammu and Kashmir, India. An initial examination using mitochondrial and nuclear genes showed that they belong to a new species. To describe this new species, a variety of analyses were conducted, including reconstructing phylogenetic relationships based on multiple genes, characterizing the nematodes at the morphological and morphometric levels, performing self-crossing and cross-hybridization experiments, and isolating and characterizing their symbiotic bacteria. Results: The newly discovered species, Heterorhabditis casmirica n. sp., shares 94% mitochondrial cytochrome C oxidase subunit I gene (COI) sequence identity with Heterorhabditis bacteriophora and Heterorhabditis ruandica, and 93% with Heterorhabditis zacatecana. Morphologically, it differs from H. bacteriophora in its infective juvenile phasmids (present vs. inconspicuous) and bacterial pouch visibility in the ventricular portion of the intestine (invisible vs. visible); genital papilla 1 (GP1) position (at manubrium level vs. more anterior), and in its b ratio (body length/neck length), c ratio (tail length/bulb width), and D% [(excretory pore/neck length) × 100]. Other morphological differences include anterior end to the nerve ring distance (77–100 vs. 121–130 μm), V% [(anterior end of vulva/body length) × 100] (46–57 vs. 41–47) in hermaphroditic females; rectum size (slightly longer than the anal body diameter vs. about three times longer), phasmids (smaller vs. inconspicuous), body length (0.13–2.0 vs. 0.32–0.39 mm), body diameter (73–150 vs. 160–220 μm), anterior end to the excretory pore distance (135–157 vs. 174–214 μm), and demanian ratios in amphimictic females. Morphological differences with H. ruandica and H. zacatecana were also observed. Furthermore, H. casmirica n. sp. did not mate or produce fertile progeny with other Heterorhabditis nematodes reported from India. It was also discovered that H. casmirica n. sp. is associated with Photorhabdus luminescence subsp. clarkei symbiotic bacteria. Conclusions: The discovery of H. casmirica n. sp. provides novel insights into the diversity and evolution of Heterorhabditis nematodes and their symbiotic bacteria. This new species adds to the catalog of entomopathogenic nematodes in India. [ABSTRACT FROM AUTHOR]

Summary: Two populations of bacterial-feeding nematodes belonging to the genus Panagrolaimus were recovered from infected slugs collected from gardens, agricultural areas and nurseries of the Baghpat district (India). Initial morphological characterisation of these populations show that they resemble Panagrolaimus labiatus from China and Bulgaria, P. burdwanensis from India, and P. cf. labiatus from Iran. To clarify taxonomical affiliations, we morphologically compared these two new populations to those recovered from China, Bulgaria, India and Iran. In addition, we sequenced several taxonomically relevant genes and used them to reconstruct phylogenetic relationships. Our results show that the two Indian populations do not significantly differ morphologically from the specimens used to describe the species P. labiatus , and also do not differ among them. We only observed small variations in the size of males and females. In addition, morphologically, the nematodes used to describe P. burdwanensis are very similar to the nematodes used to describe P. labiatus and to the two populations described in this study. Therefore, we propose P. burdwanensis as a junior synonym of P. labiatus and that the two populations recovered from India belong to the P. labiatus species. Phylogenetic analyses using the nucleotide sequences of the internal transcribed spacer (ITS), 18S and 28S rRNA gene sequences support our morphological conclusions. Our study therefore provides a detailed morphological description and molecular marker 18S and 28S gene sequences that can support future taxonomical studies of this species and highlights the importance of using both molecular and morphological data for the proper description of soil microfauna. [ABSTRACT FROM AUTHOR]

A new nematode species belonging to the family Alloionematidae was originally isolated by Dr Marie Anne Felix on 16 December 2007 from a rotting coconut at the boat boarding point in Estuary island resort, Poovar, Kerala, India. Both morphologically and molecularly, the new isolate resembles Neoalloionema tricaudatum but, unlike N. tricaudatum this species has no phasmidial 'horns' in the juvenile stage, even though prominent structures in the mid-tail of dauer juveniles were observed. Females are characterised by a body length of 947 (869-1030) pm, vulva in the mid-body region, long, and tapering tail with a minute post-anal swelling. Males are 678 (606-757) pm long with a long tapering tail that is very thick at base. They are further characterised by seven pairs of genital papillae and a single genital papilla. Dauer juveniles are only 391 (364-434) µm long, thin and almost straight when heat-killed. Large, prominent phasmids are located laterally at the mid-tail region and lateral fields consisting of a single ridge are present. Several morphological and molecular differences encouraged us to describe the nematode as N. indicum n. sp. The ecology of the newly described species is unknown, but it is probably a saprophytic bacteriophagous nematode preferring rotting organic material. [ABSTRACT FROM AUTHOR]