New record of the genus Parkellus Jairajpuri, Tahseen & Choi, 2001 with redescription of parkellus menzeli male in Viet Nam

ACADEMIA JOURNAL OF BIOLOGY 2020, 42(2): 29–33 DOI: 10.15625/2615-9023/v42n2.14716 29 NEW RECORD OF THE GENUS Parkellus Jairajpuri, Tahseen & Choi, 2001 (Mononchida: Mononchidae) WITH REDESCRIPTION OF Parkellus menzeli MALE IN VIETNAM Vu Thi Thanh Tam 1,2,* , Grazyna Winiszewska 3 1 Institute of Ecology and Biological Resources, VAST, Vietnam 2 Graduate University of Science and Technology, VAST, Vietnam 3 Museum and Institute of Zoology, Polish Academy of Science (PAS), Wilcza 64, 00-679 Warszawa, Poland Received 20 December 2019, accepted 20 May 2020 ABSTRACT The genus Parkellus with a redescription of Parkellus menzeli male is recorded and illustrated for the first time from Vietnam. One male of Parkellus menzeli was collected from Y Ty Commune, Bat Xat natural conservation area, Lao Cai Province, northwest Vietnam; its measurements and features corresponded well with the type population from Crasta im Textal, Switzerland and other populations from Poland. Keywords: Free-living soil nematodes, natural conservation area, new record, Vietnam. Citation: Vu Thi Thanh Tam, Winiszewska G., 2020. New record of the genus Parkellus Jairajpuri, Tahseen & Choi, 2001 (Mononchida: Mononchidae) with redescription of Parkellus menzeli male in Vietnam. Academia Journal of Biology, 42(2): 29–33. https://doi.org/10.15625/2615-9023/v42n2.14716. *Corresponding author email: vtam7572@yahoo.com ©2020 Vietnam Academy of Science and Technology (VAST) Vu Thi Thanh Tam, Winiszewska G. 30 INTRODUCTION The genus Parkellus (Mononchidae, Prionchulinae) was elected as a new genus by Jairajpuri et al. (2001), based on a new species P. parkus from Korea, which Choi & Choi (1997) previously described as Iotonchus zschokkei (Menzel, 1913). The genus Parkellus is close to the genus Coomansus Jairajpuri & Khan, 1977 but differs in having a large and spacious buccal cavity, posterior placed dorsal tooth and complex of gubernacum in the male. However, Zullini & Peneva (2006) and Andrassy (2009) did not support to separate the genus Parkellus because the distinguishing characters, such as larger and spacious buccal cavity; posteriorly situated dorsal tooth and a complex gubernaculum can be observed also in some species of Coomansus and regarded the genus Parkellus as a synonym of Coomansus. More recently, the genus Parkellus was reviewed by Ahmad & Jairajpuri (2010) and nine species of Coomansus zschokkei group were transferred to this genus (Ahmad & Jairajpuri, 2010). The species Parkellus menzeli was first described by Loof and Winiszewska-Slipinska (1993) as Coomansus menzeli based on some specimens with very great body size among population of C. zschokkei of Menzel´s collection. Also in their article, eight other Iotonchus species were transferred from Iotonchus to the genus Coomansus, and belonging to the zschokkei-group, viz. I. arcuticaudatus Eroshenko, 1975; I. cobbi Eroshenko, 1975; I. monticola Eroshenko, 1975; I. mucronatus Eroshenko, 1975; I. paraamphigonicus Eroshenko, 1975; I. silvius Eroshenko, 1975; I. simmenensis (Kreis, 1924) Schneider, 1939 and I. zschokkei (Menzel, 1913) Cobb, 1917. This species, C. menzeli, is distinguished from C. zschokkei by the large body size, larger buccal cavity (65– 78 m), the sub-acute spicule head and bifurcate spicule tip (Loof & Winiszewska- slipinska, 993). More recently, C. menzeli and those related species were transferred to the genus Parkellus Jairajpuri, Tahseen & Choi, 2001 by Ahmad & Jaraijpuri (2010) in their book of “Mononchida: The predaceous nematodes”. Up to now, of ten already described species in this genus worldwide (Ahmad & Jairajpuri, 2010), three species from Europe; eight species from Asia including Far East, Kazakhstan, Korea, Japan 8 species and one species from North America. The species P. menzeli was recorded only in Europe including Poland, Switzerland, Czech Republic, Romania, Ukraine and Bungaria (Ahmad & Jairajpuri, 2010; Mladenov et al., 2019). Until now, the genus Parkellus is unknown among predaceous nematodes of the order Mononchida from Vietnam (Nguyen, 2007). The record of P. menzeli from Lao Cai Province is the first report of the genus Parkellus Jairajpuri, Tahseen & Choi, 2001 for the nematode fauna in Vietnam. MATERIALS AND METHODS Soil samples were collected randomly around the base of trees from Bat Xat natural conservation area in Lao Cai Province, Northern Vietnam. Nematodes were extracted from soil samples using modified Baermann funnel technique (Southey, 1986). They were killed by heat, fixed in 4% formaldehyde, transferred to anhydrous glycerol (Seinhorst, 1959), and mounted on glass slides for microscopic observation. Photographs were taken with Nikon digital camera connected onto a Nikon Eclipse Ni microscope and the images were edited using Adobe Photoshop CS6. Permanent slide was stored at the Department of Nematology, Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology (VAST), Ha Noi, Vietnam. RESULTS AND DISCUSSION Parkellus menzeli (Loof & Winiszewska- slipinska, 1993) Ahmad & Jairajpuri, 2010 Materials: only one male in good condition. Measurements: see table 1. Male: Body large size. Habitus after fixation ventrally arcuate, particularly toward posterior end. Under light microscope: cuticle smooth, 7 µm thick at the base of New record of the genus 31 oesophagus, numerous irregular spaced cuticular pores all over the body. Lip region 54 m wide, offset from the body contour, rounded head with arrangement of labial and cephalic papillae in two circles. Amphideal fovea cup-shaped, at 5 m from the anterior end of buccal cavity. Buccal cavity large size, ventral ridge present with 72 m long and 36.4 m wide, barrel shaped, narrowing at base; its wall strongly sclerotized. Table 1. Comparison of morphometric data of Parkellus menzeli (Loof & Winiszewska-slipinska, 1993) Ahmad & Jairajpuri, 2010 Local Parkellus menzeli Crasta im Textal, Switzerland Poland Lao Cai, Vietnam Characters Loof and Winiszwska-Slipinska (1993) Present paper n 1 ♂ (topotype) 9 ♂♂* 1 ♂ L (mm) 3.23 2.51–3.40 3.32 a 33 23–32 30.8 b 4.2 3.8–4.7 4.0 c 33 17–25 27.7 c’ 1.1 1.6–2.1 1.6 Buccal cavity length (µm) 72 66–74 71.8 Buccal cavity width (µm) 41 28–34 36.4 Apex of dorsal tooth position from base of buccal cavity (µm) 43 34–48 37 Lip region width (µm) 58 52–56 54.2 Neck length (m) 776 705–892 833.6 Body width (m) 98 94–131 107.8 Anal body width (m) 86 72–88 73.6 Tail length (m) 98 124–168 120 Spicule length (m) 136 108–148 121.2 Supplement number 25 19–26 20 Rectum (m) - 52–76 50.9 Notes: -: No information; *: From several populations. Dorsal tooth large, with sharp apex, pointing forward. Apex of dorsal tooth situated in posterior half of buccal cavity, at 37% of buccal cavity length from its base. Oesophagus cylindroid, 834 m long, nerve ring located at 203 m or approximately 24% of its length from anterior end. Excretory pore is very conspicuous with distinctly sclerotized terminal duct and large sac; situated just after nerve ring about 227 m or approximately 27% of its length from anterior end. Oesophago-intestinal junction non- tuberculate. Cardia projecting into intestinal lumen. Rectum straight, thick-walled and muscular, 50.9 m. Reproductive system two testis. Spicule curved, 121 m long with sub-acute head and bifurcate terminus. Gubernaculum thick, 37 m long; lateral guiding piece 22 m long, bifurcate tip. The series of 20 supplements occupying approximately 13% of the body length. The distance in between cloacal opening and posteriormost supplement 16.5 m. Tail conoid shape, curved, 120 m long or about 1.6 anal body diameter. Caudal gland inconspicuous without gland opening. Tail tip fine, slightly round with hyaline as 14 m long. Vu Thi Thanh Tam, Winiszewska G. 32 Female: Not found. Remarks: The measurements of Vietnamese specimens corresponded well with those of topotype and paratype specimens from type population from Crasta im Textal, Switzerland and Poland (Loof & Winiszewska-Slipinska, 1993). Locality: Y Ty Commune (altitude at 2090 m), Bat Xat natural conservation area, Lao Cai Province, Vietnam. Figure 1. Parkellus menzeli (Loof & Winiszewska-Slipinska, 1993) Ahmad & Jairajpuri, 2010 A, B. Head region; C, D. Male tail region; E: Spicule subacute head and bifurcate tip Aknowlegment: This result is a part of research project “Taxonomy studies on Polish and Vietnamese nematodes from genera Parkellus and Jensenonchus”, code number QTPL01.03/19-20 is funded by Vietnam Academy of Science and Technology (VAST). REFERENCES Jairajpuri M. S., Tahseen Q., Choi Y. E., 2001. 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