Description of Hoplolaimus bachlongviensis sp. n. (Nematoda: Hoplolaimidae) from banana soil in Vietnam

Abstract Background The genus Hoplolaimus Daday, 1905 belongs to the subfamily Hoplolaimine Filipiev, 1934 of family Hoplolaimidae Filipiev, 1934 (Krall 1990). Daday established this genus on a single female of H. tylenchiformis recovered from a mud hole on Banco Island, Paraguay in 1905 (Sher 1963, Krall 1990). Hoplolaimus species are distributed worldwide and cause damage on numerous agricultural crops (Luc et al. 1990 Robbins et al. 1998). In 1992, Handoo and Golden reviewed 29 valid species of genus Hoplolaimus Dayday, 1905 (Handoo and Golden 1992). Siddiqi (2000) recognised three subgenera in Hoplolaimus: Hoplolaimus (Hoplolaimus) with ten species, is characterized by lateral field distinct, with four incisures, excretory pore behind hemizonid; Hoplolaimus (Basirolaimus) with 18 species, is characterized by lateral field with one to three incisures, obliterated, excretory pore anterior to hemizonid, dorsal oesophageal gland quadrinucleate; and Hoplolaimus (Ethiolaimus) with four species is characterized by lateral field with one to three incisures, obliterated; excretory pore anterior to hemizonid, dorsal oesophageal gland uninucleate (Siddiqi 2000). Since then, Hoplolaimus puriensis Ali, Shaheen & Pervez, 2009 has been described (Ali et al. 2009). Up to now, there have been two species of genus Hoplolaimus reported in Vietnam, viz H. seinhorsti and H. chambus (Nguyen and Nguyen 2000). New information Hoplolaimus bachlongviensis sp. n. was isolated from banana soil in Bach Long Vi Island, Vietnam. The female of this species is described and illustrated below. Some diagnostic characters of this species include body slightly curved ventrally, offset lip region exhibiting three to four annules, lateral field reduced, pharyngeal glands with six nuclei, excretory pore anterior to hemizonid, epiptygma absent, intestine not overlapping rectum and male was not found.


Introduction
In many surveys of plant parasitic nematodes on bananas in agriculture and natural forest systems in mainland of Vietnam, only two species Hoplolaimus seinhorsti Luc, 1958 andH. chambus Jairajpuri &Baqri, 1973 were recorded (Nguyen and Nguyen 2000). During a survey of plant parasitic nematodes in Bach Long Vi Island (located about 130 km off the mainland of Vietnam), a Hoplolaimus sp. was collected which was morphologically different from other known species. Herein this species is morphologically characterised and described as Hoplolaimus bachlongviensis sp. n.

Materials and methods
The nematodes were detected from banana soil samples in Bach Long Vi Island, Vietnam (20°07'52.8" N, 107°43'56.6" E). Soil nematodes were extracted using the decanting and modified Baermann tray method (Whitehead and Hemming 1965). Measurements were made on permanent slides of heat-killed nematodes with fixative TAF and ethanol-glycerin dehydration according to the method described by Seinhorst (1959) and modified bySeinhorst (1959), De Grisse (1969. For morphological examination, nematodes were observed through the Olympus BX-51 light microscope, and photographed with an Olympus U-TV 0.5xC-3 digital camera.

Diagnosis
Hoplolaimus bachlongviensis sp. n. is characterized by lip region set off, lateral field reduced, represented by a single incisure on the body, but often indistinct, Pharyngeal glands with six nuclei, excretory pore prominent and located seven annules anterior to hemizonid, epiptygma absent, intestine not overlapping rectum, male absent.

Etymology
The species is named after the geographic location, Bach Long Vi Island of Vietnam.

Type material
Female holotype and seven female paratypes deposited in the nematode collection of the Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet str., Hanoi, Vietnam. Accession numbers: IEBR.Nema4050-1 (one female hoplotype); IEBR.Nema4050-2 (8 female paratypes).