body cavity of crocodylus johnsoni in western … · western australia; 3 paratypes (females) in...

J. Parasitol., 90(2), 2004, pp. 322-326 ? American Society of Parasitologists 2004

MICROPLEURA AUSTRALIENSIS N. SP. (NEMATODA: MICROPLEURIDAE) FROM THE BODY CAVITY OF CROCODYLUS JOHNSONI IN WESTERN AUSTRALIA

Franti?ek Moravec, Winston R. Kay,* and Russell P. Hobbst Institute of Parasitology, Academy of Sciences of the Czech Republic, Branisovska 31, 37005 Ceske Budejovice, Czech Republic. e-mail: moravec@paru. cas. cz

ABSTRACT: A new nematode species, Micropleura australiensis n. sp., is described on the basis of specimens found in the peritoneal cavity of the Australian freshwater crocodile, Crocodylus johnsoni Krefft, from the Ord River area, Western Australia. The new species is mainly characterized by the length of spicules (0.360-0.366 mm) and gubernaculum (0.096-0.105 mm), the number and arrangement of male caudal papillae (4 preanal and 6 postanal pairs), and the postequatorial vulva. To date, it is the first species of Micropleura reported from Australia. Micropleura trionyxi Agrawal, 1966, and M. lissemysia Chattervati, 1985, are considered junior synonyms of M indica Khera, 1951.

From June to October of 2002, 30 Australian freshwater

crocodiles, Crocodylus johnsoni Krefft, 1873, originating from the Ord River area, Western Australia, were examined by W. Kay as a part of a dichloro-diphenyl-trichloro-ethane study. While extracting liver and fat tissues, nematode specimens were opportunistically collected from the peritoneal cavity of these animals. A detailed study of their morphology shows that they represent a new species of the dracunculoid genus Micropleura Linstow, 1906, described below.

MATERIALS AND METHODS

A total of 30 specimens of C. johnsoni were examined: 10 animals from the lower Ord River, 10 from the Ord River Irrigation Area Drain 4, and 10 from the upper Ord River at the southern end of Lake Argyle. The nematodes were occasionally collected from their peritoneal cavity. They were fixed in 10% formaldehyde solution and cleared with glyc- erine for examination. Drawings were made with the aid of a Zeiss microscope drawing attachment. After examination, the specimens were briefly placed in 4% formaldehyde solution and then transferred to 70% ethanol, in which they were stored. For scanning electron microscopy (SEM), body fragments of 2 females were postfixed in 1% osmium tetroxide, dehydrated through a graded alcohol series, critical point dried, and sputter coated with gold. They were examined with a JSM- 6300 scanning electron microscope at an accelerating voltage of 15 kV. All measurements are given in millimeters unless otherwise stated. The scientific names of reptiles are according to Uetz et al. (2002).

DESCRIPTION

Micropleura australiensis n. sp. (Figs. 1-3)

General: Body white, elongate, tapering to both ends. Cuticle thin, with very fine transverse striations; body surface bearing numerous small, elongate cuticular inflations or bosses with mi- nute papillalike formations on their upper side. Cephalic end rounded. Oral aperture small, circular, surrounded by a rather wide, slightly elevated ring of cuticle; inner margin of oral aperture appearing to be provided with numerous small papillalike formations. Cephalic papillae small, 14 in number, arranged in 2 circles: outer circle formed by 4 submedian pairs of papillae, inner circle by 4 single papillae forming 1 dorsal pair, 1 ventral pair, and a pair of larger lateral papillae; small lateral amphids posterior to lateral papillae. Small conical deirids located just anterior to level of excretory pore. Esophagus distinctly divided

Received 6 May 2003; revised 7 August 2003; accepted 7 August 2003. * Department of Zoology and Entomology, School of Life Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.

t Division of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia.

into short anterior muscular and much longer and wider, almost cylindrical glandular portion; approximately posterior half of muscular esophagus distinctly darker than anterior one; large cell nuclei of 3 esophageal glands usually distinct. Nerve ring encircling base of muscular esophagus. Excretory pore slightly posterior to anterior end of glandular esophagus; excretory cell large, spindle shaped, attached by its posterior part to glandular esophagus. Intestine straight, light colored, fairly narrow. Males distinctly smaller than females.

Male (2 specimens; measurements of holotype in parenthe- ses): Length of body 7.167-7.385 (7.385), maximum width 0.272-0.354 (0.272). Cuticular inflations distinct, 0.006-0.009

(0.006) high, distributed throughout body length. Length of entire oesophagus 1.463-1.673 (1.463), forming 20-23% (20%) of body length. Muscular esophagus 0.321-0.394 (0.321) long, maximum width 0.054-0.060 (0.060); glandular esophagus 1.142-1.292 (1.142) long, maximum width 0.109-0.114 (0.114); length ratio of both parts of esophagus 1:3.3-4.6 (1: 4.6). Cell nucleus of dorsal esophageal gland 1.387 (not established) from anterior body end. Nerve ring and excretory pore 0.299-0.354 (0.299) and 0.456-0.530 (0.456), respectively, from anterior extremity. Deirids in holotype (0.450) from anterior end. Posterior end of body spirally coiled. Ventral precloacal surface with conspicuous elevations of striated cuticle, resembling caudal ala in lateral view. Caudal papillae: 4 pairs of preanal and 6 pairs of postanal subventral papillae present. Spicules slender, needlelike, almost equally long, with somewhat distended proximal ends and pointed distal ends; distal parts of spicules provided with narrow, ventral membranous ala; length of right spicule 0.360-0.366 (0.360), length of left spicule 0.354-0.357 (0.357). Gubernaculum large, well scler- otized, 0.096-0.105 (0.105) long. Tail conical, 0.222-0.435 (0.435) long, with smooth rounded tip.

Female (13 specimens; measurements of allotype in paren- theses, those of 1 juvenile specimen in brackets): Length of body of specimens containing larvae 14.266-35.061 (23.338) [9.561], maximum width 0.544-1.673 (1.319) [0.408]. Cuticu-

lar inflations fairly small, inconspicuous, up to 0.006 high, be- ing indistinct in larger specimens. Length of entire esophagus 2.312-3.264 (2.897) [1.904], forming 9-16% (12%) [20%] of body length. Muscular esophagus 0.476-0.734 (0.653) [0.394] long, maximum width 0.095-0.190 (0.136) [0.082]; glandular esophagus 1.822-2.584 (2.271) [1.496]; length ratio of both parts of esophagus 1:3.5-3.8 (1:3.5) [1:3.8]. Cell nucleus of dorsal esophageal gland 1.700-2.462 (0.462) [1.387] from anterior body end. Nerve ring and excretory pore 0.490-0.694

322

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MORAVEC ET AL.-MICROPLEURA AUSTRALIENSIS N. SP. 323

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FIGURE 1. Micropleura australiensis n. sp., female. A. Anterior end of gravid specimen. B. Cephalic end of gravid specimen, lateral view. C. Cephalic end of gravid specimen, apical view (reconstructed from SEM micrographs). D. First-stage larva from uterus. E. Region of vulva. F- G. Cuticular inflations, lateral views. H-I. Caudal end of 2 different gravid specimens, lateral and subventral views. J. Tail of young specimen, lateral view.

(0.612) [0.367] and 0.517-0.979 (0.789) [0.530], respectively, from anterior extremity. Deirids not located. Intestine narrow, light colored. Rectum considerably reduced, formed by thin hy- aline tube; 3 unicellular rectal glands present. Tail of smaller specimens conical, with smooth, rounded tip; tail of larger specimens nearly rounded; 2 dorsolateral papillalike projections situated at about midlength of tail; length of tail 0.150-0.231 (0.177) [0.177]. Vulva slightly postequatorial, situated 7.698-

12.022 (12.022) [4.978] in smaller specimens, at 52-54% (52%) [52%] of body length. Vagina considerably reduced, ori- ented posteriorly from vulva. Amphidelphic. Ovaries short. Uterus in larger females occupying almost whole space of body cavity, extending approximately from anterior end of glandular esophagus to intestinal end; uterus containing huge numbers of first-stage larvae. Body of larvae (n = 10) 0.453-0.480 long, 0.015-0.021 wide; esophageal part 0.129-0.153 long (17-20%

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FIGURE 2. Micropleura australiensis n. sp. A. Anterior end of male. B. Caudal end of male (paratype). C. Young female, general view. D. Distal end of spicule. E. Precloacal region of male (holotype). F. Tail of male (holotype).


MORAVEC ET AL.-MICROPLEURA AUSTRALIENSIS N. SP. 325

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FIGURE 3. Micropleura australiensis n. sp., SEM micrographs of gravid female. A. Cephalic end, apical view. Bar = 10 pm. B. Tail, ventral view. C. Oral aperture. D. Deirid. E. Cuticular inflation on body surface. a, amphid; b, subdorsal caudal projection; c, anus; i, submedian cephalic papilla of inner circle; 1, lateral cephalic papilla of inner circle; p, submedian cephalic papilla of outer circle.

of body length); slender, sharply pointed tail 0.252-0.360 long (33-46% of body length).

Taxonomic summary

Type host: Crocodylus johnsoni Krefft (Crocodylidae, Cro- codylia); total body length 92-135 cm.

Site of infection: Peritoneal cavity. Type locality: Upper Ord River (southern end of Lake Ar-

gyle) (16?37'38"S, 128?41' 19"E), Western Australia (collected 1 October 2002).

Other locality: Lower Ord River (downstream from Lake Ku- nunurra) (15?34'46"S, 128?33'50"E), Western Australia.

Prevalence and intensity: Estimated prevalence in all local- ities 70-80%; intensity undetermined: 1-14 (mean 4) nematodes were collected from individual crocodiles, which may be proportional to the numbers in each crocodile (not every worm in each animal was collected).

Deposition of types: Holotype, allotype and 13 paratypes (1 male and 12 females) in the Western Australian Museum (cat-

alog WAM V 4376, WAM V 4377, WAM V 4378) in Perth, Western Australia; 3 paratypes (females) in the helminthologi- cal collection of the Institute of Parasitology, Academy of Sci-

ences of the Czech Republic (ASCR), in Ceskd Budejovice, Czech Republic (catalog N-804).

Etymology: The specific name of this nematode relates to the country of its origin.

Diagnosis: To date, 5 inadequately described species of Mi- cropleura are known: M. vivipara Linstow, 1906 (type species), from Gavialis gangeticus (Gmelin) in India, M. vazi Travassos, 1933, from Caiman crocodilus (L.) in South America, and M.

indica Khera, 1951, M. trionyxi Agrawal, 1966, and M. lissemysia Chattervati, 1985, from freshwater turtles (Aspideretes gangeticus (Cuvier), Lissemys punctata (Lacepede), and Ka- chuga sylhetensis (Jerdon)) in India (Ivashkin et al., 1971; Bak- er, 1987; Sood, 1999). Of these, only M. vivipara somewhat resembles M. australiensis n. sp. in the length of spicules (0.30-0.33 mm) and gubernaculum (0.07 mm), but in contrast to the new species, its vulva is distinctly pre-equatorial, divid-


326 THE JOURNAL OF PARASITOLOGY, VOL. 90, NO. 2, APRIL 2004

ing the body 5:6 (vs. slightly postequatorial), the male possesses 7 pairs (4 preanal and 3 postanal) (vs. 10 pairs) of caudal papillae, and the cephalic end is reported by Baylis (1939) to have 2 lateral cephalic papillae forming elevated conical structures. The remaining species can be easily separated from M. australiensis by the length of spicules (shorter than 0.29 mm) and the number (5-8 or 11 pairs) and arrangement of caudal papillae in the male, in addition to some other features. The new species also differs from congeners in the geographical distri- bution (Australia vs. India or South America).

DISCUSSION

The morphology of all Micropleura spp. is inadequately known, including that of its type species M. vivipara. This was established by Linstow (1906) from specimens collected from the body cavity of G. gangeticus of the Zoological Gardens, Calcutta, India; however, his description is poor, and judging from the given body length (35 mm) of the male and the description and illustration of the male caudal end, e.g., presence of 2 lateral elevations on the tail, it is apparent that the author mistook a female for the male. The species was later rede- scribed by Baylis and Daubney (1922) and Baylis (1924).

According to Linstow (1906), the head end of M. vivipara bears 6 papillae, but Baylis (1939) reported 10 cephalic papillae in this species, of which 2 lateral papillae formed conical structures. Only 6 cephalic papillae were reported in the original descriptions also for M. vazi, M. indica, and M. trionyxi (Tra- vassos, 1933; Khera, 1951; Agrawal, 1966), but Siddiqi and Jairajpuri (1963) mentioned 14 cephalic papillae in 2 circles and a pair of lateral amphids in M. indica; the number of cephalic papillae in M. lissemysia was not established. However, the cephalic papillae in this nematode group are poorly visible under the light microscope, and as mentioned by Moravec et al. (1998) for philometrids, the only reliable method of studying these papillae is SEM. Of Micropleura spp., this method has so far been used only in the South American species M. vazi and in Micropleura sp. from Crocodylus moreletii Dumeril and Bibron in Mexico (Moravec, 2001; Moravec and Prouza, 2003), where 14 papillae were found; the same number and arrangement was observed in M. australiensis in this study. In all these cases, a pair of lateral papillae is somewhat larger than the remaining papillae; small pocketlike amphids are situated posterior to the lateral papillae.

The presence of deirids is characteristic of many dracunculoid genera, but these were not reported for any Micropleura species; only recently Moravec and Prouza (2003), using SEM, have discovered small deirids in M. vazi. The presence of deirids in M. australiensis suggests that these may be present in all congeneric species.

The male caudal end in Micropleura spp. is firmly spirally coiled and, therefore, it is rather difficult to study details in its structure. Some authors reported the presence of 1 or 2 caudal alae in these nematodes; this feature was sometimes used as a

character of the family or for the separation of species, e.g., Ivashkin et al. (1971) and Sood (1999), but this study indicates that the "lateral caudal ala" is rather a modified, elevated ventral cuticle. It is highly desirable to study the male ventral caudal surface by SEM.

The situation of fairly large papillalike protrusions on the female tail of M. australiensis seems to be characteristic of this

species (a similar situation of these formations was illustrated in M. vivipara by Baylis and Daubney [1922]); in contrast, these are located terminally in M. vazi and Micropleura sp. from C. moreletii (Moravec, 2001; Moravec and Prouza, 2003).

The species of Micropleura from crocodilians (M. australiensis, M. vazi, and M. vivipara) differ distinctly from each other in their morphology, host types, and geographical distri- butions. On the other hand, the 3 poorly described congeneric species from turtles are established on the basis of unreliable or doubtful features (their type specimens are lacking); they occur in the same host species in India, and apparently, they represent just a single species, M. indica, with M. trionyxi and M. lissemysia as its junior synonyms.

ACKNOWLEDGMENTS

The authors thank the staff of the Laboratory of Electron Microscopy of the Institute of Parasitology, ASCR, in Ceske Budejovice for their technical assistance and Irena Husakova of the same Institute for her

help with the illustrations. This study was supported by grant 524/03/ 0061 from the Grant Agency of the Czech Republic.

LITERATURE CITED

AGRAWAL, V. 1966. Three new reptilian nematodes from Lucknow. Transactions of the American Microscopical Society 85: 107-114.

BAKER, M. R. 1987. Synopsis of the Nematoda parasitic in amphibians and reptiles. Occasional Papers in Biology No. 11, Memorial Uni- versity of Newfoundland, St. John's, Newfoundland, Canada, 325 p.

BAYLIS, H. A. 1924. The male of Micropleura vivipara (Nematoda). Annals and Magazine of Natural History, Series 9, 13: 199-201.

. 1939. The fauna of British India, including Ceylon and Burma. Nematoda. Vol. II. (Filarioidea, Dioctophymoidea and Trichinel- loidea). Taylor and Francis, London, U.K., 274 p.

, AND R. DAUBNEY. 1922. Report on the parasitic nematodes in the collection of the Zoological Survey of India. Memoirs of the Indian Museum 7: 263-347.

IVASHKIN, V. M., A. A. SOBOLEV, AND L. A. KHROMOVA. 1971. Camal- lanata of animals and man and the diseases caused by them. Os- novy nematodologii 22. Nauka, Moscow, Russia, 388 p. [In Rus- sian.]

KHERA, S. 1951. A new nematode, Micropleura indica n. sp. belonging to the family Philometridae Baylis and Daubney, 1926 from the Ganges tortoise Trionyx gangeticus Cuvier. Indian Journal of Hel- minthology 3: 55-58.

LINSTOW, 0. 1906. Parasites from the gharial (Gavialis gangeticus Geoffr.). Journal and Proceedings of the Asiatic Society of Bengal, New Series 2: 269-271.

MORAVEC, F 2001. Some helminth parasites from Morelet's crocodile, Crocodylus moreletii, from Yucatan, Mexico. Folia Parasitologica 48: 47-62.

, K. NAGASAWA, AND K. OGAWA. 1998. Observations on five species of philometrid nematodes from marine fishes in Japan. Sys- tematic Parasitology 40: 67-80.

, AND A. PROUZA. 2003. New data on the morphology of two nematode species from Caiman crocodilus from Venezuela. Acta Parasitologica 48: 111-118.

SIDDIQI, A. H., AND M. S. JAIRAJPURI. 1963. On Micropleura indica Khera, 1951 (Nematoda: Dracunculidae) from a new host Lissemys punctata, with studies on its life history. Zeitschrift fur Parasiten- kunde 23: 99-105.

SOOD, M. L. 1999. Reptilian nematodes from South Asia. International Book Distributors, Dehra Dun, India, 299 p.

TRAVASSOS, L. 1933. S6bre os filarideos dos crocodilos sud-americanos. Mem6rias do Instituto Oswaldo Cruz 27: 159-164.

UETZ, P., R. CHENNA, T. ETZOLD, AND J. HALLERMANN. 2002. The EMBL Reptile Database. Available at: www.reptile-database.org. Ac- cessed 10 December 2002.


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