Morphological and molecular observations of nematodes belonging to the family Hoplolaimidae from the Thar Desert, Pakistan

The populations of ectoparasitic nematodes belonging to the family Hoplolaimidae viz., Helicotylencshus dihystera , H. exallus , H. pseudorobustus , and Hoplolaimus seinhorsti were recovered from the soil surrounding the roots of khejri tree ( Prosopis cineraria ) and Leptadenia pyrotechnica during summer at high temperature (max 50 °C) from the Thar Desert, near Umerkot, Sindh, Pakistan. The species were identified on the basis of morphological and molecular characteristics. According to morphology and morphometrics, these species agree with those of the type species and topotype specimens. The phylogenetic analysis of Helicotylenchus species based on the 18S rDNA placed the studied population in the same clade with other Helicotylenchus with a 1.00 posterior probability. Additionally, phylogenetic analysis of H. seinhorsti using 18S rDNA and cox1 mtDNA sequences placed the Pakistani population close to H. columbus and H. indicus , however, in a different clade with 1.00 posterior probability support value. Measurements, illustrations, LM pictures, and molecular characters of 18S rDNA , and cox1 mtDNA are given. In conclusion, despite the confirmation of the studied species, their ecological role in the agricultural field of Pakistan should be investigated.