Redescription and synonymization of Oscheius citri Tabassum, Shahina, Nasira and Erum, 2016 (Rhabditida, Rhabditidae) from India and its taxonomical consequences

Abstract

A population of a nematode species belonging to the genus Oscheius was isolated in western Uttar Pradesh, India. Morphological and morphometrical studies on this species showed its high similarity with six species described previously from Pakistan (Oscheius citri, O. cobbi, O. cynodonti, O. esculentus, O. punctatus and O. sacchari). The molecular analysis of the ITS1-5.8S-ITS2 rDNA sequences of the Indian population and the six species described from Pakistan showed that all the sequences are almost identical. Thus, based on morphological and molecular characteristics, all of the six above-mentioned Pakistani species and Indian strain do not differ from each other, hence can be considered synonyms. The correct name for this taxon is the first described species O. citri. Additionally, the phylogenetic analysis of the 18S rDNA and the 28S rDNA sequences showed that Oscheius citri is sister to the clade formed by O. chongmingensis and O. rugaoensis from China. The high similarity of morphological and morphometric characteristics of O. citri and other species, O. maqbooli, O. nadarajani, O. niazii, O. shamimi and O. siddiqii, suggest their conspecificity; however, lack of molecular data for these species does not allow this hypothesis to be tested.

Morphological, Morphometrical and Molecular Characterization of Oscheius siddiqii Tabassum and Shahina, 2010 (Rhabditida, Rhabditidae) from India with Its Taxonomic Consequences for the Subgenus Oscheius Andrássy, 1976

“…Prior to the light microscopic studies and morphometry analyses, the nematodes were propagated using the last instar larvae of G. mellonella by injecting 10 greater wax moth larvae with approximately 2000 surface-sterilized dauer larvae in sterilized Petri dishes using a 1 mL insulin syringe. The larvae died within 48–72 h [ 7 ]. Adult generations (females and males) and 3rd stage juveniles were isolated from the white trap within 7–10 days [ 18 ].…”

“…More recently, Abolafia and Peña-Santiago [ 4 ] categorised both the groups as subgenera, dividing them into Oscheius : Oscheius and Dolichorhabditis , respectively, according to the division proposed by Andrássy [ 5 , 6 ]. With respect to the subgenus Oscheius (or insectivorus-group), 23 valid species have been described at the time of writing [ 4 , 7 ] ( Supplementary Table S1 ).…”

“…This fact complicates the systematics of the group, and a revision of these species is necessary to elucidate their taxonomic status. In our recent study [ 7 ], we compared an Indian population of Oscheius sp. from India and six Oscheius species described from Pakistan ( Oscheius citri, O. cobbi, O. cynodonti, O. esculentus, O. punctatus, and O. sacchari ).…”

Potential of Oscheius tipulae nematodes as biological control agents against Ceratitis capitata

“…saproxylicus , and O . tereticorpus , whose ability to kill insects have not been tested, however, suggesting that this trait could be much more spread in the genus than it is currently thought [ 22 , 27 , 32 – 40 ]. Clearly, several species of this nematode genus have great potential to complement the repertory of commercially available Steinernema and Heterorhabditis nematodes to control agricultural pests.…”