Proleptonchus japonicus, Ahad, Sumaya & Ahmad, Wasim, 2016

Ahad, Sumaya & Ahmad, Wasim, 2016, Three new and a known species of the genus Proleptonchus Lordello, 1955 (Nematoda: Leptonchidae) with a diagnostic compendium of the genus, Zootaxa 4189 (1), pp. 115-133 : 126-132

Proleptonchus japonicus n. sp.

( Figs. 6 , 7 )

Measurements. See Table 3 .

Description. Female: Medium sized nematodes, 0.91–1.04 mm long; body cylindroid, tapering slightly towards both extremities, generally straight or slightly curved ventrally. Cuticle with two distinct layers, 2–3 µm thick at midbody and 3–4 µm on tail. Outer layer thin; inner layer with irregular outline and loose; radial refractive elements abundant. Lateral chords occupying about 31–33% of the midbody diameter. Dorsal, ventral and lateral body pores indistinct.

Lip region cap-like, offset by slight constriction, 2.5–2.6 times as wide as high or about one-third of the body diameter at neck base; lips slightly raised, rounded and amalgamated. Amphids cup-shaped with aperture located at the level of cephalic constriction, occupying about 0.6–0.7 times the lip region diameter. Stoma inverted flaskshaped, with sclerotized walls. Odontostyle attenuate, 0.5–0.6 times the lip region diameter long, with very fine lumen, aperture not seen. Odontophore slightly arcuate, 2.0–2.2 times the odontostyle length. Guiding ring simple, refractive, at 0.6–0.7 times lip region diameter from anterior end. Pharynx consists of a slender and non-muscular anterior part, separated from basal bulb by a constriction. Pharyngeal bulb short, pyriform with thickened lumen in posterior region, occupying about 18–20% of total neck length. Cardia rounded, hemispherical, about one-sixth of the corresponding body diameter long. Nerve ring at 47–52% of neck length from the anterior end.

Genital system mono-prodelphic. Ovary reflexed, 139–209 µm long, not reaching the oviduct-uterus junction; oocytes arranged in single row except near tip. Oviduct joining the ovary subterminally, measuring 200–215 µm, consisting of a slender portion and a poorly developed par dilatata. Oviduct-uterus junction marked by a sphincter. Uterus short, tubular, measuring 42–56 µm. Posterior genital branch 0.6–0.7 times the midbody diameters long. Vagina cylindrical; pars proximalis vaginae 8–9 µm long, its wall encircled by muscles; pars distalis vaginae short, 2 µm long with slightly curved walls; pars refringens absent. Vulva apparently a transverse slit. Prerectum 4.1 and rectum 1.3–1.4 times anal body diameter long. Tail short and rounded-conoid, 0.7–0.8 anal body diameter long.

Male. Not found.

Type habitat and locality. Soil around the roots of grasses (unidentified) from Koibuchimachi, Mito C., Ibaraki, Japan. Collected by Dr. M. Araki on December 7, 2011.

Type specimens. Holotype female on slide Proleptonchus japonicus n. sp. / 1; paratype female on slide Proleptonchus japonicus n. sp. / 2; deposited with the nematode collection of the Department of Zoology, Aligarh Muslim University, India .

Etymology. The new species is named after its type locality Japan.

Diagnosis and relationship. Proleptonchus japonicus n. sp. is characterized by having 0.91–1.04 mm long body; lip region cap-like, set off by a slight constriction; odontostyle 5 µm and odontophore 10–11 µm long; pharynx consists of a very slender, non-muscular anterior part, separated from pyriform basal bulb by a constriction, with thickened lumen in posterior region, occupying about 18–20% of total neck length; female genital system mono-prodelphic; posterior uterine sac small, 20–24 µm long; transverse vulva and short, roundedconoid tail.

The new species is distinctive in having a non-muscular, very slender anterior part of pharynx and pharyngeal bulb having thickened lumen in posterior region.

In presence of a short posterior uterine sac, the new species comes close to P. t e re s Jairajpuri, 1964 and P. brevisaccus Goseco, Ferris & Ferris, 1974 . However, it differs from the former in having lower a and b ratio (a = 30.5–32.7 vs 36; b = 5.9–6.1 vs 4.3–5.6); odontostyle straight (vs odontostyle arcuate); odontophore not sclerotized (vs odontophore slightly sclerotized); vulva comparatively anterior (V = 50.8 vs 57%); smaller posterior uterine sac (0.6–0.7 vs 2.5 times the midbody diameter) and in the absence of male (vs presence).

From P. brevisaccus , it differs in having slightly smaller body (L = 0.91–1.04 vs 1.22–1.64 mm); amphid simple (vs amphid duplex); smaller odontostyle (5 vs 7 µm); odontophore not sclerotized (vs sclerotized); pharyngeal bulb short pyriform (vs pharyngeal bulb cylindroid); slightly longer posterior uterine sac (20–24 vs 13– 19 µm) and tail rounded-conoid (vs hemispheroid).

Character n L a b c ć V Lrd ods Neck ph.bulb prerect. tail Spicule vms geo.distru reference

(mm) (µm) length Length length Length length Length

(µm) (µm) (µm) (µm) (µm) (µm)

aestivus 5 0♀♀ 1.2—1.5 3 2—3 5 6.0—7.5 7 0—7 5 5 2—5 8 Brazil Lordello, 1 9 5 5

10♀♀ 1.3—1.5 30—35 6.0—7.3 70—78 - 52—60 - - - - - - India Jairajpuri, 1964

2♀♀ 1.1—1.2 24—30 5.8 76—93 0.6—0.8 59—61 7.5—8 5—6 195— 20 7 40?—60 13—15 Vietnam Nguyen et al, 2012 amphidius 1♀ 1.3 37 6.2 74 0.9* 58 10* 6* 180* 30* - 20*

1Ƌ 1.2 42 6.0 59 1.0* - - - - - - 25* 32 5 India Jairajpuri, 1964 attenuatus 7♀♀ 1.6—1.8 55—62 7.2—7.7 98—113 0.6—0.7 49— 54 8—9 7.5—8.5 228—26 0 48—52 152 — 20 4 15—18

9ƋƋ 1.5—1.8 53— 61 7—8 84—103 0.7—0.9 - 8—9 7.5—8.5 213—25 0 46—50 164— 25 5 17—21 32— 35 3—6 New Zealand Ahmad et al., 2003 … …continued on the next page = Lip region diameter ods = Odontostyle ph. bulb = Pharyngeal bulb prerect. length = Prerectum length = Ventromedian supplements geo. distru = Geographical distribution (*) = Calculated measurements from illustrations

The new species further differs from the above two species in the nature of its pharynx, i.e. very slender anterior part of pharynx and in the nature of the pharyngeal bulb.

Figures

FIGURE 6. Proleptonchus japonicus n. sp. A. Entire female. B. Anterior region. C. Anterior end showing amphid. D. Pharyngeal region. E. Pharyngeal bulb. F. Female genital system. G. Vulval region. H. Female posterior region.

FIGURE 7. Proleptonchus japonicus n. sp. A. & B. Anterior region. C. Anterior end showing amphid. D. & E. Pharyngeal bulb. F. Female genital system. G. Vulval region. H. & I. Female posterior region and showing caudal pore. (Scale bar A – C, G = 10 µm; D – F, H, I = 20 µm)

Tables

TABLE 3. Measurements of Proleptonchus japonicus n. sp. (All measurements in µm).

Characters L (mm) Body diameter at neck base	Holotype female 1048 28	Paratype female 915 26
Body diameter at mid body Body diameter at anus a b	32 21 32.7 5.9	30 20 30.5 6.1
c c`V G1 G2 Lip region diameter Lip region height Amphid aperture Odontostyle length Odontophore length	6 1.6 0.8 50.8 24.4 2.2 9 3.5 6 5 11	6 1 0.7 52.1 27.9 2.1 8 3 6 5 10
Guiding ring from anterior end Nerve ring from anterior end Neck length Expanded part of pharynx	6 83 176 31	6 77 148 30
Cardia length Anterior genital branch Posterior genital branch Vaginal depth Vulva from anterior end Prerectum length	5 256 24 16 533?	4 256 20 16 477 82
Rectum length Tail length	28 17	28 15