Morphological and molecular characterization of Longidorus patuxenticus n. sp. (Nematoda: Longidoridae) from Maryland and California, USA

Authors: KANTOR, MIHAIL - Pennsylvania State University; SUBBOTIN, SERGEI - California Department Of Food And Agriculture; IM, BILL - Pennsylvania State University; Handoo, Zafar

Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2023
Publication Date: 11/8/2023
Citation: Kantor, M., Subbotin, S., Im, B., Handoo, Z.A. 2023. Morphological and molecular characterization of Longidorus patuxenticus n. sp. (Nematoda: Longidoridae) from Maryland and California, USA. Nematology. 26{2):1. https://doi.org/10.1163/15685411-bja10296.
DOI: https://doi.org/10.1163/15685411-bja10296

Interpretive Summary: Plant-parasitic nematodes are microscopic worms that feed on plants and cause an estimated ten billion dollars of crop losses each year in the United States and 173 billion dollars globally. The new species being described, belongs to a group of nematodes that are of importance to agriculture as parasites as well as vectors of plant viruses (nepoviruses) and cause damage to host plants due to direct feeding on root cells. One problem with determining the extent of damage to crop plants is that the nematodes present in many areas are not known. In this study, a team of ARS scientists from Beltsville, MD and a colleague from California analyzed by both morphological and molecular means a new species of needle nematode isolated during a nematode survey of a natural grass, tall fescue, along the bank of Western Branch of Patuxent River, Upper Marlboro, Maryland. They also discovered this new species in California and studied how to distinguish this new species from closely related species with molecular and anatomical features. This discovery is significant because new molecular and morphological information obtained for this new species will facilitate future identifications of this needle nematode. Therefore, this research will be used by scientists,diagnosticians, growers, action agencies, and extension agencies involved in nematode research and control.

Technical Abstract: Plant-parasitic nematodes belonging to the genus Longidorus are polyphagous or obligate root ectoparasites of many plants. A new species, Longidorus patuxenticus n. sp., was collected during a nematode survey of natural grass, tall fescue, Lolium arandinaceum (Schreb.) Darbysh along the bank of Western Branch of Patuxent River in Upper Marlboro, Maryland. Females and juveniles were recovered from soil samples using the sugar centrifugal flotation and Baermann funnel extraction methods. Morphologically, female body length ranges from 3787 to 5150 µm, with a set off lip region which is truncate and slightly swollen anteriorly, odontostyle (77-92 µm), odontophore (40-53 µm), vulva located at 46-50%, tail conoid to bluntly rounded. No males were found. Longidorus patuxenticus n. sp. is morphologically like L. breviannulatus, L. elongatus, L. martini, L. americanus, L. grandis, L. sabalanicus and L. sturhani but differs from these species either by the odontostyle, odontophore, total stylet length and few other characters such as set off lip region and slightly swollen/rounded laterally, the amphideal fovea pocket-shaped without lobes at base and a peg like tail terminus. Phylogenetic analysis of the D2-D3 of 28S rRNA gene sequences placed L. patuxenticus in a clade with L. litchi, L. fangi, L. jonesi, L. diadecturus and Longidorus sp. The 28S rRNA gene sequence of L. patuxenticus n. sp. was similar to that of Longidorus sp. collected from Juglans sp. growing in Butte County, California, USA. Both morphological observations and molecular analysis of the 28S, ITS1 rRNA and COI gene sequences indicated that the specimens collected from soil around the rhizosphere of grass from Upper Marlboro, MD and Butte County, CA, represents a new needle nematode species.