Meloidogyne paramali, Gu & Fang & Ma & Shao & Zhuo, 2023

Gu, Jianfeng, Fang, Yiwu, Ma, Xinxin, Shao, Baolin & Zhuo, Kan, 2023, Meloidogyne paramali n. sp. (Nematoda: Meloidogyninae) and First Report of M. marylandi in maple and yacca tree from Japan, Journal of Nematology 55 (1), pp. 1-18 : 3-7

Meloidogyne paramali * n. sp.

( Figs. 1–4 )

Measurements

Measurements of J2 are available in Table 1 .

Description

Female (n = 5)

Females were rare, and only 5 could be measured. The measured parameters are the following – length (including neck): 820.6 ± 82.0 (710–962) μm; length of neck: 166.0 ± 19.4 (135–190) μm; body width: 737.2 ± 72.8 (630–849) μm; DGO from stylet base: 5.6 ± 0.8 (4.7–6.5) μm; and stylet length: 14.5 ± 1.5 (12.5–16.9) μm.

Females were completely enclosed by gall tissue. Their bodies were translucent-white, variable in size, and ovoid to pear-shaped. The neck was sometimes prominent. The body cuticle was distinctly annulated, and annuli were smaller in the anterior neck region. The head region was set off from body and the cephalic framework was weakly sclerotized, with distinct head caps and indistinct annulations. The stylet cone was slender and slightly curved; the shaft was observed to have a gradually wider shape posteriorly near the junction, with knobs. The knobs were well developed, round to transversely ovoid, and slightly concave anteriorly. The excretory pore was located posterior to stylet base. The distance of dorsal pharyngeal gland orifice to stylet base was approximately 5 μm to 7 μm. Perineal patterns were oval or irregular, with distinct lateral lines; dorsal arches were often round, and dorsal and ventral striae smooth. A dorsal arch with shoulders was sometimes present, formed by a slight indentation of the dorsal striae near the lateral lines. The anus was within a cuticlar fold, and the phasmids were conspicuous. Inter-phasmidal distance (22.2 [18.9–28.7] μm) was wider than the length of vulval slit (17.3 [16.1– 18.3] μm), the distance of the vulva from an imaginary line joining the phasmids was 25.3 (24.0–26.9) μm, and the distance between the vulva and anus was 16.3 (12.4–19.1)μm.

Male (n = 2)

Males are rare, and only two were recovered. Their characteristics are the following – body length: 1,545 μm and 1,819 μm; body width: 32.1 μm and 47.0 μm; a: 48.1 and 38.7; stylet length: 18.9 μm and 20.1 μm; DGO: 6.5 μm and 7.0 μm; spicules’ length: 31 μm and 33 μm; head to the middle of valve plate: 93 μm and 99 μm; and tail length: 9.8 μm and 11.4 μm.

The bodies were vermiform, tapering anteriorly, bluntly rounded posteriorly twisting through 90°, and the tails were bluntly rounded. Body annuli were large, distinct, and 2.4 μm to 2.9 μm in width. The lateral field was with four lines in the mid body region, beginning as two lines at about the stylet base and ending as two or three lines at the tail tip. The cephalic framework was moderately developed, and vestibule extensions were distinct. The head was set off from the body, without labial annulus. The stylet was robust, with rounded basal knobs. The cone was slightly longer than the shaft. The shaft was cylindrical, widening slightly near the junction, with knobs. The dorsal pharyngeal gland orifice branched into three channels, with distinct ampulla. The procorpus was distinct, while the median bulb was ovoid. Pharyngo-intestinal junction occurred at the level of nerve ring, and was indistinct. Three nuclei were present in gland lobe. The testis was outstretched or anteriorly reflexed. Spicules were arcuate, and gubernaculum distinct. The tail was short with broadly rounded terminus, with indistinct phasmids.

Second-stage juvenile (J2)

About 50 J2s were observed, and 20 of them were measured. The bodies were observed to be vermiform, clearly annulated, and straight or slightly ventrally bent near the tail region. The anterior ends were truncated, with the head region only slightly set off from the body. The lateral region was slightly larger than one-third of the body width, with four lines. The stylet was delicate, and the cone was straight, narrow, and sharply pointed; the shaft was observed to become slightly wider posteriorly, while the knobs were small and rounded. The procorpus was faint, while the metacorpus was oval-shaped with an enlarged lumen lining. The isthmus was clearly defined, while the pharyngo-intestinal junction was difficult to observe. The gland lobe variable in length, and it ventrally overlapped the intestine. The excretory pore was distinct, and was located 64 μm to 81 μm from the head, while the hemizonid was three to five annuli posterior to the excretory pore. The tail was conoid, with finely rounded to broad pointed terminus, but never sharply pointed. The hyaline tail terminus was very short (4.3 [3.0–4.9] μm), and indistinct. The phasmids were small, difficult to observe, and located posterior to the anus.

Eggs

The eggs had a morphology that is typical for this genus. The egg masses were usually protruding from root tissues on the roots.

Type habitat and locality

The nematodes in question were isolated from Japanese maple ( Acer palmatum Thunb. ) imported from Chiba, Japan and inspected in Ningbo Port , P.R. China during May, 2018 .

Type material

To earmark the necessary holotype female, five females, two males, and 26 second-stage juvenile paratypes (slide number 5445-1~5445-10) have been deposited at the nematode collection of Ningbo Customs Technology Center, China. Additionally, five paratype J2s (slide numbers T620) are deposited in the Canadian National Collection of Nematodes, Ottawa, Canada.

Diagnosis and relationships

Meloidogyne paramali n. sp. is characterized by J2 with a short tail length of 32.2 (24–36.8) μm, finely rounded to broad pointed tail terminus, and an extremely short hyaline tail terminus of 4.3 (3.0–4.9) μm. The perineal pattern of females was oval or irregular, with round dorsal arch, distinct lateral lines, and fine and smooth striae. The polytomous key codes of the new species according to Subbotin et al. (2021) are: Female: A21, B2, C32, D4; Male: A21, B3, C2, D1, E2, F2; J2: A2, B23, C43, D34, E12, F34.

Based on the perineal pattern of females (A4) and the similar J2 tail length (C43), we may infer that Meloidogyne paramali n. sp. is very similar to M. mali and M. nataliei Golden et al., 1981 . The new species can be distinguished from M. mali by the perineal pattern, which has a distinct lateral field; additionally, the hyaline terminus of the J2 tail is shorter (4.3 [3.0– 4.9] μm vs. 8.2 [4.8–12.7] μm), and the tail is finely rounded to broadly pointed in M. paramali n. sp., but it is never sharply pointed as it is in M. mali .

It differs from M. nataliei by shorter J2 body length (433 [402–455] μm vs. 599 [539–641] μm), shorter J2 stylet length (11.7 [10.8–12.5] μm vs. 22.4 [21.9–22.8] μm), shorter tail hyaline portion (4.3 [3.0–4.9] μm vs. 8.4 [7.0–11.0] μm), and much smaller c value (13.6 [11.7–18.9] vs. 22 [19–26]).

M. caraganae Shagalina et al., 1985 , M. coffeicola Lordello and Zamith, 1960 , M. kikuyensis De Grisse, 1961 , M. nataliei , M. suginamiensis Toida and Yaegashi, 1984 , M. turkestanica Shagalina et al., 1985 , and M. vandervegtei Kleynhans, 1988 have similar J2 tail length (C4 or 43), but the perineal patterns are different: D3 for M. caraganae , M. suginamiensis , M. turkestanica and M. vandervegtei , D2 for M. coffeicola , and D5 for M. kikuyensis .

In the phylogenetic trees ( Figs. 6–9 ), M. vitis , M. paramali n. sp., and M. mali formed a well-separated clade, which is named molecular group VIII ( Subbotin et al., 2021). Meloidogyne paramali n. sp. differs from M. vitis in that the J2 tail is shorter (32.2 [24–36.8] μm vs. 57.43 [47.01–63.77] μm), and the J2 c value is bigger (13.6 [11.7–18.9] vs. 6.95 [6.15–8.77]).

Figures

Figure 1: Meloidogyne paramali n. sp. A: J2; B: Anterior region of J2; C: Anterior region of male; D: Lateral region of male; E: Lateral region of J2; F: Male tail region; G: Variations of J2 tail; H, I: Female perineal patterns. (Scale bars = 10 μm).

Figure 2: Light photomicrographs of Meloidogyne paramali n. sp. J2. A: Entire body; B: Anterior region; C: Post median bulb region; D: Lateral region; E–K: Tail region. (Scale bars = 10 μm).

Figure 3: Light photomicrographs of Meloidogyne paramali n. sp. male and female. A: Male head region; B: Male lateral region; C: Male tail region; D–H: Female perineal patterns. (Scale bars = 10 μm).

Figure 4: Light photomicrographs of host plant roots infected by Meloidogyne paramali n. sp. and female. A: Root-knot; B: Female.

Figure 6: Phylogenetic relationships of the Melodidogyne paramali n. sp. within the genus Meloidogyne as inferred from Bayesian analysis of the 18S rDNA sequences using the SYM + I + G model (ln L = −9,656.5775; freqA = 0.2500; freqC = 0.2500; freqG = 0.2500; freqT = 0.2500; R(a) = 1.1490; R(b) = 2.9493; R(c) = 1.9703; R(d) = 0.5777; R(e) = 4.7703; R(f) = 1.0000; Pinva = 0.4140; Shape = 0.4400). Posterior probabilities are given in clades node. Newly obtained sequences are indicated in bold and the sequence codes are given in specimen-clone.

Figure 7: Phylogenetic relationships of the Melodidogyne paramali n. sp. within the genus Meloidogyne as inferred from Bayesian analysis of the ITS region of rDNA sequences using the GTR+ G model (ln L = –15,611.9209; freqA = 0.2778; freqC = 0.1784; freqG = 0.2084; freqT = 0.3354; R(a) = 1.1160; R(b) = 2.3301; R(c) = 1.4759; R(d) = 0.7128; R(e) = 2.9133; R(f) = 1.0000; Shape = 0.5730). Posterior probabilities are given in clades node. Newly obtained sequences are indicated in bold and the sequence codes are given in specimen-clone.

Figure 8: Phylogenetic relationships of the Melodidogyne paramali n. sp. within the genus Meloidogyne as inferred from Bayesian analysis of the D2–D3 region of the 28S rDNA sequences using the TVM + I + G model (ln L = –9,976.1624; freqA = 0.2157; freqC = 0.1943; freqG = 0.2737; freqT = 0.3163; R(a) = 1.1061; R(b) = 3.8613; R(c) = 1.8155; R(d) = 0.4745; R(e) = 3.8613; R(f) = 1.0000; Pinva = 0.2180; Shape = 0.7340). Posterior probabilities are given in clades node. Newly obtained sequences are indicated in bold and the sequence codes are given in specimen-clone.

Figure 9: Phylogenetic relationships of the Melodidogyne paramali n. sp. within the genus Meloidogyne as inferred from Bayesian analysis of the intergenic region between CO II and 16S rDNA sequences using the GTR + G model (ln L = −9,869.8599; freqA = 0.3676; freqC = 0.0265; freqG = 0.0939; freqT = 0.5121; R(a) = 3.2156; R(b) = 5.9094; R(c) = 1.5251; R(d) = 2.6383; R(e) = 13.9890; R(f) = 1.0000; Shape = 0.6340). Posterior probabilities are given in clades node. Newly obtained sequences are indicated in bold and the sequence codes are given in specimen-clone.