Laimaphelenchus sinensis, Gu & Maria & Fang & Liu & Bian & Chen, 2020

Gu, Jianfeng, Maria, Munawar, Fang, Yiwu, Liu, Lele, Bian, Yong & Chen, Xianfeng, 2020, Description of Laimaphelenchus sinensis n. sp. (Nematoda: Aphelenchoididae) from declining Chinese pine, Pinus tabuliformis in Beijing, China, Journal of Nematology 52 (1), pp. 1-9 : 2-5

LaimaphelenChus sinensis n. sp. ( Figs 1 and 2 ).

Measurements

Measurements of the new species are given in Table 1 .

Description

Female

Body is slender, cylindrical, and J-shaped when heat killed. Cuticle has fine annulations. Lateral field has four incisures. Lip region is convex in lateral view, offset, more than twice as broad as high. Stylet is 12.3 (11.8-12.6) µm long, divided into two parts with small basal swellings and conus occupying Ca 40% of its total length. Procorpus is cylindrical, and metacorpus (median bulb) is strongly developed and oval shaped, with centrally situated valves. Dorsal pharyngeal gland orifice opens into lumen of metacorpus with Ca one metacorpal valve length anterior to metacorpal valve. Pharyngo-intestinal junction is one metacorpal valve length posterior to the base of metacorpus. Nerve ring is less than one body diam. length posterior to metacorpus. Pharyngeal gland lobe is slender, overlapping intestine dorsally. Excretory pore is located slightly posterior to nerve ring. Reproductive tract is mono-prodelphic and located to the right of intestine. Organs are arranged as ovary, oviduct, spermatheca, crustaformeria, uterus, vagina + vulva and post-uterine sac. Single, outstretched ovary, developing oocytes arranged in 1 to 2 rows, and several well-developed oocytes arranged in single row. Oviduct is short and connected with an ovoidto oblonged-shaped spermatheca, filled with sperm cells. Spermatheca is formed by thick tissue, forming an expansion in the gonad, i.e. not forming a clear branch. Crustaformeria is not conspicuous. Vagina is slightly inclined anteriorly to body axis, with massive sclerotization, but sometimes invisible. Vulva is a traverse slit, and anterior vulval lip is modified into a small vulval flap covering the vulval region. Post-uterine sac and vagina are usually closed with no special structure such as a pair of three-celled structures. Post-uterine sac is long, extending for Ca 39.7 to 55.8% of vulval–anus distance, and sometimes filled with sperm. Anus is distinct, and area at anal lips is slightly elevated. Tail is conoid, slightly ventrally curved with a mucron of about 2 µm long, and appears like a stalk-like terminus with multiple (8-10) projections.

Male

Body is slender, cylindrical, and slightly ventrally arcuate when heat-relaxed. Cuticle and anterior body region are similar to female. Testis, outstretched, located on the left side of intestine. Anterior part of testis contains developing spermatocytes in a single row and gradually develops into two rows. Cloacal lips are non-protruded. Spicules are paired, condylus is broad squarish to rounded shaped with triangular rostrum, capitulum is straight to slightly bent in some individuals, and lamina/calomus is complex and smoothly curved to distal end. Distal ends of spicule have rounded terminus. Two pairs of papillae are present: one pair is subventral precloacal papillae (P2) located at the same level of cloacal opening, and the other pair is subventral postcloacal papillae (P3) located at mid of the tail. Tail is conoid ventrally curved with several tubercles. Bursa is absent.

Etymology

The species epithet is formed from the country of origin.

Differential diagnosis

The L. sinensis n. sp. can be characterized by the lateral field with four lines and the excretory pore situated posterior to the nerve ring. The male spicules are 14.0 (13.2–15) µm long along the curved median line, condylus is broad squarish to rounded shaped with triangular rostrum, capitulum is straight to slightly bent in some individuals, and distal ends of spicule have a rounded terminus. Two pairs caudal papillae are present. Bursa is absent. Female have a vulval flap. Tail is conoid and ventrally curved with a single stalk-like terminus with 8 to 10 projections.

Note: All measurements are in µm and in the form of mean ±SD (range).

The new species has a vulval flap and four lateral lines, whereas none of the other LaimaphelenChus species exhibits this combination except these four species: L. persiCus ( Asghari et al., 2012); L. preissii ( Zhao et al., 2006b) ; L. simlaensis ( Negi et al., 2009) and L. unituberCulus ( Bajaj and Walia, 2000).

The new species can be differentiated from L. persiCus by tail terminus morphology (single stalk with 8 to 10 projections vs 4 pedunculate tubercles ending with 4 to 6 finger-like protrusions), longer female body L= 968 (914–1064) vs 763 (615–925) µm, higher c value =28 (25–32.9) vs 21.8 (17.5–24.7) and smaller spicule lengths 14.0 (13.2–15) vs 20.4 (19–21.0) µm; from L. preissii by size of anterior vulval lip (smaller vs elongated, well developed), spicule morphology (condylus broad squarish to rounded shaped with triangular rostrum distal ends of spicule with rounded terminus vs condylus and rostrum broad ellipsoidal with bluntly rounded terminus), bursa (absent vs present), smaller spicule lengths 14.0 (13.2–15) vs 22 to 28 µm, shorter body length of male 876 (750–956) vs 1,088 (1,000 –1,218) and female 968 (914–1,064) vs 1,185 (1,007 –1,386) µm and smaller of female tail 34.9 (29–38.6) vs 44 (32–64)µm; from L. simlaensis by the spicule morphology (condylus broad squarish to rounded shaped with triangular rostrum vs condylus broad rounded with pointed rostrum) and length 14.0 (13.2–15) vs 16 to 18 µm, spicule devoid of gubernaculm like structure vs present, female tail terminus morphology (single stalk with 8 to 10 projections vs 3 to 5 finger-like fine processes and male having 2 pairs of caudal papillae vs 3; from L. unituberCulus by posterior position of excretory pore from anterior end (posterior to nerve ring vs at the same level of it), vaginal scelorotization (medium vs massive), the spicule morphology (condylus broad squarish to rounded shaped with triangular rostrum vs condylus conoid with pointed rostrum and straight condylus) longer body length of male 876 (750–956) vs 640 (520–720) µm and female 968 (914–1,064) vs 740 (690–800)µm and male having 2 pairs of caudal papillae vs 3.

Figures

Figure 1: Line drawings of LaimaphelenChus sinensis n. sp. A: Entire female; B: Entire male; C: Anterior region; D: Female posterior region showing vulva and post-uterine sac; E: Lateral lines F, G: Female tail terminus; H: Male tail; I: Spicule. (Scale bars =A, B=20µ m; C-I=10µ m).

Figure 2: Light photomicrographs of LaimaphelenChus sinensis n. sp. A: Entire female; B: Entire male; C: Lateral lines; D: Anterior region; E: Female posterior region showing vulva and postuterine sac; F, G: Vulval regions; H: Female tail; I-K: Female tail terminus; L-N: Male tails arrows showing position of caudal papillae (Scale bars =A, B=20µm; C-N= 10µ m; Abbreviations: ex, excretory pore).

Tables

Table 1. Morphometrics data for LaimaphelenChUS SinenSiS n. sp.

		Female	Male
Character	Holotype	Paratypes	Paratypes
n	–	6	5
L	914	968 ± 46.1 (914 – 1064)	876 ± 69.1 (750 – 956)
a	42.1	41.5 ± 1.9 (38.6 – 44.8)	46.2 ± 2.6 (42.4 – 50)
b	11.2	11.7 ± 0.6 (11.2 – 12.7)	10.5 ± 0.6 (9.4 – 11.1)
b’	4.3	4.8 ± 0.4 (4.3 –5.6)	4.6 ± 0.3 (4.1– 4.9)
c	25.3	28 ± 3.1 (25 – 32.9)	19.9 ± 1.4 (17.9 – 22.3)
c’	2.6	2.6 ± 0.3 (2.1 –2.9)	2.7 ± 0.2 (2.4 – 2.9)
V or T	70.5	69.1 ± 0.9 (67.7 – 70.7)	70.8 ± 4.4 (63.4 – 76.5)
Lip region height	2.3	2.4 ± 0.1 (2.2 –2.6)	2.7 ± 0.1 (2.6 – 2.8)
Lip region width	6.9	7.1 ± 0.3 (6.8 –7.4)	7.1 ± 0.6 (6.4 – 7.9)
Stylet length	12.2	12.3 ± 0.3 (11.8 – 12.6)	12.3 ± 0.6 (11.1 – 12.9)
Body diam.	21.7	23.4 ± 1.7 (21.6– 26.4)	19 ± 1.1 (17.7 – 20.9)
Median bulb width	18.9	13.2 ± 0.7 (12.4 – 14)	12 ± 0.7 (11 –12.8)
Median bulb length	12.6	18.5 ± 0.5 (17.6 – 18.9)	17.4 ± 0.8 (16.2 – 18)
Median bulb length/diam. ratio	1.5	1.4 ± 0.1 (1.3 –1.5)	1.5 ± 0.1 (1.4 – 1.5)
Excretory pore from anterior end	92.2	96.3 ± 4.7 (88 –104)	83.2 ± 2.5 (80.1 – 87)
Ovary length or testis	430	454 ± 24 (420 – 480)	622.6 ± 76.6 (476– 690)
Post-uterine sac	121	130.3 ± 6.1 (119 – 138)	–
Vulva to anus distance	270	264.2 ± 20.9 (233 – 300)	–
Post-uterine sac length/vulva to anus (%)	44.8	49.8 ± 5.5 (39.7– 55.8)	–
Anal (cloacal) body diameter	14.1	13.3 ± 0.7 (12 – 14.1)	16.3 ± 1.0 (15.3 – 18.2)
Tail length	36.1	34.9 ± 3.2 (29 – 38.6)	44.1 ± 1.8 (41.8 – 46.4)
Spicule (curved median line)	–	–	14.0 ± 0.6 (13.2 – 15)
Spicule (Chord)	–	–	15.6 ± 0.9 (14.1 – 16.6)