Fundam. appl. NemaUll., 1995,18 (2),135-138

Thraustomennis chengduensis n. gen., n. sp. (Nematoda Mennithidae) parasitizing sinensis (Wiedemann) (Diptera : Culicidae) (1)

Jinzhang SONG * and Yufang PENG ** * Institute ofMilitary Medical Sciences, Chengdu Military District, Chengdu, and ** Department ofParasitology, West China University ofMedical Sciences, Ch~ngdu, Sichuan, Pe!JfJles Republic ofChina. Accepted for publication 23 March 1994.

Summary - ThrauSUImermis chengduensis n. gen., n. sp. () is described from adults of Anopheles sinensis in Chengdu, China. The diagnostic characters of the genus Thraustomermis are: medium-sized nematodes with six hypodermal cords, six cephalic papillae, no lip papillae, relatively small arnphids, adult cuticle very thin lacking visible cross fibres, a barrel-shaped vagina which is straight and parallel to the transverse body axis, and postparasitic juveniles with a short tail appendage. The females reproduce parthenogenetically and require higher temperature (26-28 OC) for completion ofdevelopment to the postparasitic stage in the host .

Résumé - Thraustomermis chengduensis n. gen., n. sp. (Nematoda, Mermithidae) parasite d'Anopheles sinensis (Wiedemann) (Diptera : Culicidae) - Thraustomermis chengduensis, n. gen., n. sp. (Mermithidae) est décrit à partir de spécimens provenant d'Anopheles sinensis récoltés dans la province de Chengdu, Chine Populaire. Les caractères diagnostiques du genre ThrausUimermis n. gen. sont: taille moyenne, six cordes hypodermiques, six papilles céphaliques, pas de papilles labiales, amphides relativement petites, cuticule de l'adulte très mince et sans fibres transversales visibles, vagin en forme de tonneau parallèle à l'axe tranverse du corps, queue des juvéniles postparasites pourvue d'un appendice court. Les femelles se reproduisent parthénogéné­ tiquement et exigent une température élevée (26-28 OC) pour parvenir au stade postparasite dans leur hôte, le moustique. Key-words : Mermithidae, ThrauslOmermis chengduensis, Anopheles sinensis, parthenogenesis, Nematoda.

In August, 1984, while collecting eggs of Anopheles ly ruprured, cuticle lacking visible cross fibres, vulva sinensis recovered from Chengdu, four postparasitic ju­ prorruding obviously, vagina barrel-shaped and straight, veniles of mermithid nematodes were found in an egg the canal of the vagina parallel to the transverse body container. Mter transfer to sterile sand, the four post­ axis. The female reproduce parthenogenetically. Srylet parasitic juveniles ail developed to adult females after present in preparasitic juveniles. Postparasitic juveniles 11 days. These were preserved for morphological stud­ with short tail appendage, parasitized in the body caviry ies. In subsequent studies, postparasitic juveniles emerg­ of aquatic . ing from adult A. sinensis were put in sterile sand indi­ vidually. Ail individually maintained postparasitic TYPE AND ONLY SPEClES juveniles (n = 18) developed to adult females and ovi­ T. chengduensis n. sp. posited. Preparasitic juveniles hatched from mature eggs. The morphology of the adults and the character­ Thraust01nerrnis chengduensis n. sp. istic development indicated that this was a new genus (Figs 1-3) and species of Mermithidae. MEASVREMENTS Females (type population, n = 13) :L = 19.6 mm ± Thraustomerrnis n. gen. 1.6 (11.5 - 30.0); a = 86.7 ± 5.2 (63.0 - 113.9); b = 11.1 + 0.9 (8.0 - 15.4); V = 29949.2339 ± 1.9 (42.8­ DIAGNOSIS 56.2). (Nematoda: Mermithidae). Adult female elongated, Paslparasitic Juveniles (n = 7) :L = 23.5 mm ± 1.8 medium in size. Female tail without appendage, six hy­ (17.8 - 35.6); greatest ctiam = 230 ± 13.9 (186 ­ podermal cords, six cephalic papillae, no lip papillae, 282) /-Lm; V =50.3 (46.0 - 56.0); tail appendage =47 ± amphids relatively small, adulr cuticle very thin and easi- 5.5 (28.8 - 65.0) /-Lm.

(1) This investigation received financial support from UNDP/WHO Special ProgTarnme for Training in Tropical Diseases (TDR) and the Ministry of Public Health, P. R. China.

ISSN 1164-5571195/02 S 4.00 / © GaUlhier- Villars - ORSTOM 135 J. Song & Y. Peng

Preparasiticjuveniles (n = 11): L =313 ± 20.5 (243­ obviously and the vagina is barrel-shaped. The canal of 495); greatest diam = 15.0 ±0.7 (11.6 - 19.6) /-lm; stylet the vagina is straight and parallel to the transverse body =4.3 (3.7 - 5.2) /-lm. axis, not lying at any angle to the body axis. Cuticle is Eggs (n = 14) : 66 x 57 (60.1 - 70.6 x 52.3 ­ very thin. Cuticle thickness at the anterior end is 1.2 /-lm, 63.3) /-lm. at the nerve ring is 1.3 /-lm, at the vulva is lA /-lm, and at the posterior end is 1.6 /-lm. Holotype (female) :L =18.1 mm; a =79.5; b =10.8; Postparasilic Juveniles : Slightly larger than the adults, V 33.3 55.431.2. = with a short tail appendage, genital primordium located in the middle of the body. DESCRIPTION Preparasite Juveniles : Slender and active worm, pos­ Female : In fixed specimen, adult female is open C­ sess a weil developed stylet. shaped, narrowed at the anterior end, bluntly rounded Egg : Oval or spherical in shape. Egg shell thin and posteriorly, has six hypodermal cords and six cephalic transparent, single cell when oviposited. papillae. Body diameter at the level of cephalic papillae is 51 /-lm, at the nerve ring is 98 /-lm, at the vulva is TYPE MATERlAL 220 /-lm, at the end of trophosome is 121 /-lm. Yielding Holotype: Female deposited in Institute of Military ratios of 0.51, 1.0, 2.23, 1.24 when compared to the Medical Sciences, Chengdu Military District, P.R. China. width at the nerve ring. The mouth is terminal. Amphids Paratypes : Four females were deposited at West Chi­ located behing the lateral papillae, length amphidial na University of Medical Sciences, Chengdu, Si­ pouch 11.2 x 3.5 (9.2 - 12.3 x 2.9 - 3.9) /-lm. Distance chuan-61 0044, P.R. China. from nerve ring to the head is 189 (149 - 222) /-lm. The trophosome packed with storage material, begin­ TYPE HOST AND LOCALITY ing at 394 (264 - 489) /-lm from the head and ends from Adult Anopheles sinensis collected from Chengdu, Si­ 170 (110 - 437) /-lm the tail tip. The vulva protrudes chuan, P.R. China.

A

F

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Fig. 1. Thraustomermis chengduensis n. gen., n. sp. A : Adll/t female head, ventral view; B : Adll/t female lail, /ateral view; C: Lateral view ofthe vaginal regÙJn ofthe adultfemale; D: Cross-section ofadult showing six hypodermal chords; E: Face view ofthe adult showing six cephalic papillae; F: Lateral view ofthe postparasite lail.

136 FlIndam. appl. Nemawl. Thraustomermis chengduensis n. gen., n. sp.

Fig. 2. Thraustomermis chengduensis n. gen., n. sp. A .' Lateral view ofvaginal and anterior pUll oj an aduft fernale; B .' Lateral view of mature female with eggs in the utenlS; C.' Mature egg with preparasitic Juvenile; D: Head of a postparasuic juvenile.

DIAGNOSIS served in adult female or young female. This constitutes definitive evidence for parthenogenesis. Females reproduced parthenogenetically, no males were recovered. Females narrowed at the anterior end, Remarks bluntly rounded posteriorly with well-defined female re­ Sorne characters of the new genus are allied to Filip­ productive system. Amphids are small. Cuticle is very jevimennis Polezhentsev & Artyuhovsky, Slrelkovimermis thin. Vagina is barrel-shaped. The canal of the vagina is Rubtsov, Kurshymennis Zahidov & Poinar, Diximennis straight and parallel to the transverse body axis, not Nickle and Tunicamennis Schuurmans-Stekhoven & Iying at any angle ta the body axis. Mawson. The female in sorne species of Filipjevimennis is parthenogenetic (Poinar & Welch, 1968), the adult BIOLOGY cuticle lacks cross-fibres, and there are six hypodermal During three years (1984 to 1986) of collecting adult cords (Polezhentsev & Artyukhovsky, 1958; Poinar, A. sinensis in breeding places in Chengdu we found 1977,1979). However, in Filipjevimennis the vagina is parasitized adult A. sinensis in late July to the beginning S-shaped and the genus is parasitic in terrestrial insects of Octaber. Air temperature reached 26-28 oC during (Ipatyeva, 1963; Poinar, 1979). These latter characters this observational period. are in contradiction to ThrausLOmennis n. gen. where the The authors observed ail (n = 18) individually cultur­ vagina is straight, barrel-shaped; moreover, the new ge­ ed single adult female ovipositing eggs and that these nus is parasitic in aquatic insects. These characters ctis­ eggs continued development to preparasitic juveniles. tinguish Thrauslomennis n. gen. from Filipjevimennis. In Mature female with weil defined female reproductive Slrelkovimennis amphids are medium in size, vagina S­ system, male reproductive organs and sperm not ob- shaped, parasitizing in aquatic insects (Poinar, 1979).

Vol. 18, n° 2 - 1995 137 J. Song & Y. Peng

2 J..lm), amphids are relatively small, me vulva projects obviously, me canal of me vagina is straight and parallel to me transverse body axis. These characters separate me new genus from Mesomermis. The female Thrauslo­ mermis n. gen. reproduces parmenogenetically which is quite different from me amphimictic reproduction found in Mesomermis. Acknowledgements The authors wish to thank Dr. E. G. Platzer for assistance in preparation of this paper. A References EBSARY, B. A. & BENNETT, G. F. (1974). Redescription of Neomesomermls flumenalls (Nematoda) from blackllies in Newfounclland. Canad. J. Zool., 52 : 65-68. IrATYEVA, G. V. (1963). [A new mermithid, Filipjemmermis pologenzevi sp. n. (Mermithidae, Nematodes) from the lar­ vae of the May beeùe (Melolontha hippocaslani F.)J. Zool. Zh., 42 : 944-947. MOLLO y , D. (1979). Description and bionomics of Meso­ mermis camdenensis n. sp. (Merrnithidae) a parasite to black (simuliidae). J. NemalOl., 11 : 321-328. NICKLE, W. R. (1972). A contribution to ourknowledge of the B Mermithidae (Nematoda). J. NemalOl., 4: 113-125. ] P01NAR, G. O., Jr. (1977). CIH key to the groups and genera of nemalOde parasites of invertebrates. Commonwealth Agricul­ Fig. 3. Thraustomermis chengduensis n. gen., n. sp. A : Prl1>­ tural Bureaux, Farnham Royal, England, CAB Press, 12 p. arasitic Juvenile emerging from an egg; B : Preparasilic Juvenile. POINAR, G. O., Ir. (1979). Nematodes for biological control of But me barrel-shaped vagina and me female Thrauslo­ insects, Boca Raton, USA, CRC Press, 277 p. mermis n. gen. reproducing parmenogentically can dis­ POINAR, G. O.,}r. & HESS, R. (1979). Mesomermls paradisus tinguish it from Sl?·elkovimermis. In Tunicamermis no sp. n. (Mermithidae : Nematoda), a parasite of Prosimulium adult males are found, me vagina is straight, barrel­ exigens D. & S. (Diptera; Simuliidae) in California. Nemat­ shaped, but cross-fibres are present in me cuticle (Schu­ ologica, 25 : 368-376. urmans-Stekhoven & Mawson, 1955; Poinar, 1979). POINAR, G. O.,}r. & SAlTO, K. (1979). Mesomermlsjaponicus Thus, ThrausLOmermis which does not have cross-fibres n. sp. (Merrnithida: Nematoda), a parasite of Simulium in me cuticle can be distinguished from Tunicamerrnis. japonicum (Simuliidae : Diptera). Jap. J. Sanil. Zool., 30 : Weich (1962), Poinar (1979), and Nickle (1972) de­ 147-149 fined me genus Afesomermis and its synonym Neomeso­ POINAR, G. O., Ir. & TAKAOKA, H. (1981). Three new mer­ mermis as : six hypodermal cords, six cephalic papillae, mithids (Nematoda) from Guatemalan blackflies (Diptera : aquatic host, large amphids, two spicules, barrel-shaped Simulüdae). Sys!. Parasil., 3: 13-19. vagina and blunt tail in bom adult sexes. Besides mese characters, me type species, Mesomermisflumenalis has a POINAR, G. O., Ir. & WELCH, H. E. (1968). A new nematode, Filipjevimermis leipsandra sp. n. (Merrnithidae), parasitic in vagina lying at sorne angle ta me body axis (Welch, chrysomelid larvae (Coleoptera).J.lnvert. Palhol., 12: 259­ 1962, Ebsary & Bennett, 1974). Many well- described 262. species of mis genus, such as J'v1. paradisus from black­ f1ies (Poinar & Hess, 1979), M. japonicus (Poinar & POLOZI-ŒNTSEV, P. A. & ARTYUKHOVSKl, A. K. (1958). Saito, 1979), M. camdenensis (MoUoy, 1979) and M. [New mermithid species.J Zool. Zh., 37: 997-1005. guaœmalae (Poinar & Takaoka, 1981) aU possess mis SCHUURMANS-STEKHOVEN,J, N. & NAWSON, P. M. (1955). character. Sorne morphological characters of me new Mermithides d'Alsace, Annls Parasil. hum. comp., 30 : 69­ genus are similar to mose of Mesomermis von Daday. 82. Born generally possess six hypodermal cords, six cephal­ WELCH, H. E. (1962). New species of Gastromermis, lsomermis ic papillae, and a barrel-shaped vagina. But in Thrauslo­ and Mesomermis (Nematoda : Mermithidae) from black mermis n. gen., me adult cuticle is very min (Jess man larvae. Ann. cnt. Soc. America, 55 : 535-542.

138 Fundam. appl. NemalOl.