Dr. Kassai Tibor - Dr. Murai Éva szerk.: Parasitologia Hungarica 10. (Budapest, 1977)

Material and Methods Between 1964 and 1975 regular collectings were made with the use of snap traps and live traps in different parts of the country. During the course of this work 348 specimens of M. arvalis were dissected. Most animals were collected in agricultural areas (alfalfa and corn fields) few of them in clearings of forests. Collectings were carried out by former and present staff members of the Parasitological Section of the Zoological Department of the Hungarian Natural History Museum: dr.I. MATSKÁSI, dr. F. MÉSZÁROS, dr. É. K. MURAI, Mr. I. SZABÓ and dr. E', VAJDA; by dr. Gy. TOPÁL mammologist (Mammalian Section of the same institution), Mr. M. JANISCH parasitologist (Department of Parasitology, University of Veterinary Sciences, Budapest), Mr. G. NECHAY (Fácánkert), dr. A. LEGÁNY and dr. J. RÉKÁSI schoolteachers, Mr. Gy. SIPOS taxidermist (Hungarian Natural History Museum) and Mr. F. HAAS agricultural engineer (Miske). Nematodes were fixed in hot Barbagallo solution. For identification they were made translucent by lactophenol. Systematics, Taxonomy and Faunistics Of 348 specimens of M. arvalis studied 175 (50. 3%) were infested by nematodes. The occurrence of six species was verified, of them Heligmosomum costellatum, Syphacia nigeriana and Heligmosomoides Iaevis were common, while Heligmosomum mixtum

, Boreostrongylus minu tus and Trichocephalus muris occurred rarely. Detailed faunistic data are shown in the Table. H. mixtum being the parasite of Clethrionomys glareolus, and T. muris that of some other rodents, these two species will be described in another paper on the nematodes of rodents. Descriptions 1. Heligmosomum costellatum (Dujardin, 1845); Fig. 2 A-E. For distribution in Hungary see the Table and Fig. 1. - Localization: small intestine. - Extensity 15.8%, intensity 1-55 specimens. Body surface with transversal cuticular crests (crête). These are without inner chitinized frames. Head end surrounded by cuticular vesicle. Male: Body length 10.5-14.2 mm, maximum width 0.21-0.25 mm. Vesicle length 0.095-013 mm. Esophagus length 0.43-0.55 mm. Nerve ring 0.22-0.27 mm, excretory pore and deirids 0.500. 68 mm from anterior end. The generally symmetrical bursa copulatrix made of two lobes. Short dorsal ray branching into four, the two inner limbs are longer than the outer ones. Externo-dorsal ray slender and long. Lateral rays with a common stem. Antero-lateral rays are the thickest, while medio-lateral ones the longest. Postero-ventral rays are well developed among the ventral ones. Prebirrsal papillae present. Thread-like spiculae 0. 83-1. 20 mm long and forked at tip. Both spiculae surrounded by a thin envelopment. Gubernaculum absent. Female: Body length 14. 6-20. 6 mm, maximum width 0. 20-0. 28 mm. Length of vesicle 0. 110.15 mm. Esophagus length 0. 53-0. 70 mm. Nerve ring 0. 21-0. 31 mm, exretory pore and deirids 0. 60-0. 80 mm from anterior end. Simple uterus. Distance of vulva 0.51-0. 64 mm, that of anus 0.09-0.11 mm from posterior end. Eggs 0.055-0.063 mm long by 0. 086-0. 100 mm wide. Rather acutely pointed tail end without terminal spike. Members of the genus Heligmosomum Railliet et Henry, 1909 are parasites of Microtinae in the Holarctic. H. costellatum was found exclusively in the Palaearctic (DURETTE-DESSET, 1971). Although, the species was mentioned also from North America by KUNS and RAUSCH