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

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 Luc, 1958 and 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 sp. was collected which was morphologically different from other known species. Herein this species is morphologically characterised and described as 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.

Taxon treatments

sp. n.

urn:lsid:zoobank.org:act:2632ABBD-A056-4AAA-B1CC-DB668A2EED07

Type status: Holotype. Occurrence: sex: female; behavior: migratory ectoparasite on banana roots; Taxon: family: ; genus: ; Location: island: Bach Long Vi; stateProvince: Hai Phong; county: Vietnam; verbatimCoordinates: ; Identification: identificationID: BLV-4050-1

Type status: Paratype. Occurrence: sex: female; behavior: migratory ectoparasite on banana roots; Taxon: family: ; genus: ; Location: island: Bach Long Vi; stateProvince: Hai Phong; county: Vietnam; verbatimCoordinates: ; Identification: identificationID: BLV-4050-2

Description

Females

(Table 1; Figs 1, 2, 3)

Table 1.

Morphometrics of sp. n. (all measurements in µm, as mean ± standard deviation (range).

Measurements	Holotype female	Paratype females
n	1	8
Body length	1439	1405 ±78.2 (1247-1493)
Stylet cone length	26	25.5±1.1 (24-27)
Stylet knob length	7	7.2±0.7 (6-8)
Stylet length	50	47.1±2.2 (44-50)
Lip region height	9	8.8±0.6 (8-9)
Lip region diam.	18	18.1±1.0 (17-20)
Anterior end to nerve ring	147	126.5±11.9 (108-147)
Anterior end to excretory pore	154	144.2±8.6 (131-154)
Anterior end to end of pharyngeal glands	248	207.5±22.2 (175-248)
DGO	6	4.2±1.2 (3-6)
Anterior end to intestine-pharyngeal valve	170	154.6±13.2 (137-174)
Anterior phasmid of body length (%)	34	34.7±4 (29-38)
Posterior phasmidof body length (%)	80	78.6±4.5 (74-84)
Max body diam.	58	58.0±4.2 (51-66)
a	24.7	24.3±1.6 (22-27)
b	5.8	6.8±0.6 (6-8)
c	53.2	55.9±5.1 (48-64)
c’	0.7	0.7±0.1 (0.6-0.8)
V	56	56.7±1.7 (53-59)
Anal body diam.	33	36.1±2.3 (33-40)
Tail length	27	25.2±1.6 (23-27)
Tail annules	13	11 ±1.6 (9-13)

Body slightly curved ventrally, rarely C-shaped, cylinder, vermiform, tapering slightly at both ends. Lip region offset, usually bearing 4 distinct annuli, sometimes 3 annuli, basal ring of lip region with 6 longitudinal striations (Figs 1a, 3a, b). Cuticular annulation prominent. Lateral field reduced and represented by the interruption of body annuli as a single incisures, but often indistinct (Figs 1e, 3d). Stylet large and strong with prominent tulip-shaped basal knob represented by three anterior projection, DGO about 4 µm behind spear base (Figs 1a, 3a). Metacorpus ovate with well-developed, sclerotized valve. Pharyngeal glands with 6 nuclei (Fig. 3a). Distinct nerve ring encircling isthmus. Excretory pore situated within range from level of nerve ring to level of esophago-intestineal valve or even somewhat more posterior. Hemizonid distinct large, two annules in length, located about seven annules behind Excretory pore (Figs 1b, 3a). Hemizonion located 8-10 annules posterior to hemizonid. Phasmids (scutella) anterior and posterior to vulva, large and conspicuous (Figs 1e, 3d). Vulva prominent, transverse slit at mid-body; epiptygma absent (Figs 1c, d, 3c). Ovaries two, outstretched (amphidelphic), spermatheca empty (Fig. 2a). Intestine not overlapping rectum (Figs 1f, 3e, f). Tail short, rounded, shorter than the anal body diameter, usually with 9-13 annuli (Figs 1f, 2b, 3e, f).

Figure 1a.

Anterior end

Figure 3a.

Anterior end

Figure 3b.

Lip region

Figure 1e.

Posterior phasmid position (arrow 2) and lateral field in lateral view (arrow 1)

Figure 3d.

Posterior phasmid.

Figure 1b.

Excretory pore (arrow 1) and hemizonid (arrow 2)

Figure 1c.

Vulva region in ventral view

Figure 1d.

Vulva region in lateral view

Figure 3c.

Vulva region (ventral view)

Figure 2a.

Spermatheca

Figure 1f.

Posterior end, intestine (arrow 1) and rectum (arrow 2)

Figure 3e.

Posterior end (ventrosublateral view)

Figure 3f.

Posterior end (lateral view)

Figure 2b.

Posterior end in ventrosublateral view

Diagnosis

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.

Notes

Males: Unknown

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).

Discussion

sp. n. is similar to , , Sher, 1963 and (Schuurmans Stekhoven & Teunissen, 1938) Sher, 1963 by having excretory pore anterior to hemizonid, lateral field reduced, represented by interruptions of annules as a single incisure, often indistinct, pharyngeal glands with six nuclei (Handoo and Golden 1992). However, sp. n. differs from by epiptygma absent vs present and number of longitudinal striations on basal ring 6 vs 8-12. It differs from by male absent vs present, epiptygma absent vs present, intestine not overlapping rectum vs overlapping rectum. sp. n. differs from in having fewer tail annuli 9-13 vs 16-22; a=22-27 vs a=30-38; b=6-8 vs b=9.1-12.4; DGO=3-6 vs DGO=9-13; epiptygma absent vs present; hemizonid located about 7 annuli behind excretory pore vs 2-5 annuli and intestine not overlapping rectum vs overlapping rectum. sp. n. differs from by male absent vs present, intestine not overlapping rectum vs overlapping rectum, epiptygma absent vs present and sperm absent vs present.

sp. n. is distinguished from Suryawanshi 1971 by having lateral field reduced and represented by the interruption of body annuli as a single incisures vs two incisures in lateral field; having longer stylet 44-50 vs 40-45; having fewer longitudinal striations on basal ring 6 vs 20; hemizonid is conspicuous vs obscure; a=22-27 vs a=26-30; b=6-8 vs b=9.7-11.5.

sp. n. differs from by lateral field reduced, represented by a single incisure on the body, but often indistinct vs four lateral lines, longer stylet 44-50 µm vs shorter stylet 32-35 µm.