Micropleura Australiensis N. Sp. (Nematoda: Micropleuridae) From the Body Cavity of Crocodylus Johnsoni in Western Australia

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 METHODSA 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 glycerine 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 minute 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 deiri...

New observations on Micropleura australiensis (Nematoda, Dracunculoidea), a parasite of crocodiles in Australia

“…from Crocodylus moreletii Duméril et Bibron from Mexico (Moravec 2001, Moravec and Prouza 2003. Moravec et al (2004) published a scanning electron micrograph ( fig. 3C) of the mouth of a female M. australiensis, where the inner margin of the oral aperture appeared to be provided with numerous small papilla-like formations.…”

“…; Moravec et al (2004) indicated that the "lateral caudal ala" in M. australiensis is rather a modified, longitudinally elevated ventral cuticle. The present SEM study confirmed the presence of one such ala situated on the right side, asymmetrically to the body axis ( Fig.…”

“…Its morphology was described mainly on the basis of light microscopy (LM), but body fragments of two female specimens were also studied by scanning electron microscopy (SEM). However, as mentioned by Moravec et al (2004), the male caudal end in Micropleura spp. is firmly spirally coiled and, therefore, it is rather difficult to study details of its structure.…”

“…Micropleura australiensis Moravec, Kay et Hobbs, 2004 is a dracunculoid nematode recently described from the peritoneal cavity of the Australian freshwater crocodile Crocodylus johnsoni Krefft in Western Australia , and is the only representative of the genus Micropleura Linstow, 1909 in the Australian zoogeographical region. Its morphology was described mainly on the basis of light microscopy (LM), but body fragments of two female specimens were also studied by scanning electron microscopy (SEM).…”