Paralepidonema baoshanensis, Zhang & Yin & Zhang, 2022

Zhang, Ningning, Yin, Shi & Zhang, Luping, 2022, A new genus and two new species of nematodes (Nematoda: Thelastomatoidea) from Ceracupes fronticornis (Westwood) (Insecta: Passalidae) in China, Zoological Systematics 47 (2), pp. 109-116 : 114-115

Paralepidonema baoshanensis sp. nov.

Diagnosis. The new genus is similar to the following genera of hystrignathid nematodes by having cervical cuticle armed with scale-like projections: Batwanema Morffe & García, 2013 , Chokwenema Morffe & García, 2013 , Lepidonema Cobb, 1898 and Salesia Travassos & Kloss, 1958 . It differs from the latter four genera by having 20 elements in the first row of spines (vs. 8 in Batwanema and Chokwenema , and 16 in Lepidonema and Salesia ). Moreover, the new genus can be easily distinguished from Batwanema by having one cephalic annule (vs. two cephalic annuli in latter), and reproductive system didelphic-amphidelphic (vs. monodelphic-prodelphic in latter). It is also different from Chokwenema by having the first cephalic annule disk-like (vs. truncate in Chokwenema ), different from Salesia by having sub-cylindrical procorpus and the cervical region with alternate rows of scales (vs. clavate procorpus and opposite rows of scales in Salesia ). In addition, the new genus is very similar to Lepidonema by the cervical region armed with scale-like projections, sub-cylindrical procorpus, and didelphic-amphidelphic genital tract, but differs from the latter by the cervical region with alternate rows of spines rather than opposite rows of spines.

Description. Female body robust. Cervical cuticle armed with alternate rows of scale-like projections, size of projections varied, some projections wide, others narrow, first row with 20 elements ( Fig. 3E ). Maximum body diameter in middle of body. Cuticle markedly annulated in spiny region, annuli less marked in rest of body. Spines originating just behind first cephalic annule, extending to level of anus. Spines scale-like from beginning location to end of stoma, gradually becoming triangular spines posterior to stoma, and finally becoming rounded dots at about one body-width anterior to vulva, terminating at anal level ( Figs 4B, D–E). Head disk-shaped, bearing 8 oval papillae arranged in 4 pairs, and a pair of amphids ( Figs 3E , 4A, C). First cephalic annule with same shape as head, wider than head, set-off from head by a deep groove ( Fig. 4A). Oral opening nearly triangular, surrounded by a cuticular flap ( Figs 4A, C). Lateral alae beginning at level of basal bulb and ending at level of vulva. Stoma relatively long, about three first cephalic annule lengths long, anterior part of stoma expanded ( Figs 3A–B ). Oesophagus consisting of a muscular, sub-cylindrical procorpus, short isthmus and basal bulb. Basal bulb sub-spherical, valve plate well developed ( Figs 3A–B ). Nerve ring encircling at middle of procorpus. Excretory pore located just posterior to basal bulb. Intestine simple, its anterior region slightly dilated. Reproductive system didelphicamphidelphic. Vulva located posterior to middle of body. Vagina extending anteriorly, connecting with two opposite uteri. Anterior ovary reflexed at level of excretory pore, posterior ovary reflexes forward about one body-width anterior to anus ( Fig. 3A ). Eggs elliptical, smooth-shelled. Tail short, conical, sharply attenuated. Male unknown.

Measurements. Female (n = 10). a = 6.4–8.8 (7.6); b = 4.1–5.6 (4.7); c = 11.6–16.9 (14.3); V = 56–63 (60); V' = 60–69 (64). Total body length 1620–2200 (1865); maximum body width 230–280 (245). Stoma 43–50 (47). Head 5–14 (11) long, 29–39 (33) wide; first cephalic annule 10–18 (13) long, 50–58 (53) wide. Total oesophagus length 372–430 (395); procorpus 261–314 (280) long; isthmus 29–43 (35) long; basal bulb 72–92 (79) long, 72–97 (84) wide. Nerve ring 190–235 (210) from anterior end; excretory pore 470–660 (579) from anterior end. Vulva 950–1370 (1118) from anterior end. Eggs 101–111 (108) long, 48–58 (52) wide; Tail 110–150 (131) long.

Type-host. Ceracupes fronticornis (Westwood, 1842) .

Site of infection. Hindgut.

Prevalence. 0.87% (1/115 host examined).

Mean intensity. 11 (11 worms from one host).

Material examined. Holotype female (HBNU-I-2021060), Baihualing, Baoshan City, Yunnan Province, China, 18 Aug. 2018, coll. Zuozhen Li. Paratypes. 9 females (HBNU-2021061–2021069), same data as holotype .

Etymology. The new species is named after the typical locality, Baoshan City, Yunnan Province, China.

Remarks. The genus Batwanema is diagnosed by having two cephalic annuli, the cervical cuticular projections consisting of a first row of eight rectangular scales that gradually bifurcate, becoming pointed spines, the reproductive system monodelphic-prodelphic, and the procorpus clavate. Three species were reported so far, namely B. congo Morffe & García, 2013 from Congo, B. annulatum (van Waerebeke, 1973) and B. latum (van Waerebeke, 1973) from Madagascar (Morffe & García, 2013b).

Chokwenema presents a similar arrangement of the cervical cuticular projections to Batwanema . The single species of the genus is C. lepidophorum Morffe & García, 2013 from Congo (Morffe & García, 2013b).

Both Lepidonema and Salesia have the genital tracts didelphic-amphidelphic and 16 elements in the first row of spines. Five species of Lepidonema have been reported, L. bifurcata Cobb, 1898 from Australia; L. brasiliensis Travassos & Kloss, 1957 and L. caracae Kloss, 1962 from Brazil; L. teresae GarcÍa, Ventosa & Morffe, 2009 and L. magnum Morffe & García, 2010 from Cuba. The single sepcies of Salesia was reported from South America (Adamson & van Waerebeke, 1992; García et al., 2009a; Morffe & García, 2010a).

Acknowledgements The authors would like to Jibiao Li of the Centre of Testing and Analysis for his technical expertise involved in SEM work, and Dr. Zuozhen Li for the collection of nematode specimens. Thanks also due to Prof. Guodong Ren of Hebei University for the identification of the host.

Figures

Figure 3. Paralepidonema baoshanensis gen. & sp. nov., female.A. Whole worm, lateral view; B. Anterior part of body, lateral view; C. Posterior end of body, lateral view; D. Egg; E. Cephalic extremity, en face view. Scale bars: A–B=100μm; C–E=50μm.