Gnathostoma malaysiae sp. n. from Rats on Tioman Island, Malaysia (Nematoda: Gnathostomidae)

Abstract

Gnathostoma malaysiae sp. n. was found in the stomach wall of rats, Rattus surifer and Rattus rattus tiomanicus trapped in a mountainous area of Tioman Island, Pahang State, Malaysia. The new species looks like Gnathostoma doloresi Tubangui, 1925, but is easily distinguished from this species by the shape of cuticular spines, the size of fertilized eggs, and the features of the caudal pedunculate papillae of the male. From the medical point of view the parasites belonging to the genus Gnathostoma Owen, 1836 are not very significant in Malaysia, although two probably indigenous cases of human gnathostomiasis were reported by Samy (1918), and Sandosham (1949). On the other hand, adult worms of the genus have been collected from some mammals in Malaysia. Gnathostoma spinigerum Owen, 1836 was reported from cats in Taiping and in Kuantan by Adams (1933), and Rohde (1962), respectively. In 1962 Miyazaki, one of the authors, and Dr. Hong-Fang Lee of the University of Singapore found three young adults of G. spinigerum in the stomach wall of one of two cats captured in the vicinity of Kuantan, Pahang (unpublished data). Moreover, Miyazaki (1960) found the eggs of this nematode in the feces of a tiger and a leopard which had been imported from Malaysia for Japanese zoological gardens. Another species of the genus reported in Malaysia is Gnathostoma doloresi Tubangui, 1925, which was found by Sandosham (1953) in a pig in Singapore. In the present paper the authors describe a new species of the genus found in the stomach wall of rats, Rattus surifer and Rattus rattus tiomanicus, trapped in a mountainous area of Pulau Tioman, an island in the South China Sea about 35 miles off the southeast coast of Pahang State, Malaysia. Received for publication 28 September 1964. * This study was supported in part by U. S. Public Health Service Grant AI 04189-02 from the ICMRT Program, Office of International Research, NIH; in part by the Office of the Surgeon General, Department of the Army. Current address of the junior author: Hooper Foundation, University of California, San Francisco. MATERIALS In April 1962 the junior author and colleagues from the Zoology Department, University of Malaya, trapped rats and other small animals at various altitudes on Tioman Island. Most of these animals were examined for helminths. Animals trapped at low altitudes-between sea level and about 1,000 ft-were all negative for Gnathostoma as follows: 6 Rattus surifer, 24 Rattus rattus tiomanicus, 3 Rattus sabanus, 1 Rattus cremoriventer, 1 Rattus exulans, 1 Callosciurus notatus, and 13 Tupaia glis. Four Rattus surifer and two Rattus rattus tiomanicus collected by Lord Medway in the forest at an altitude over 3,000 ft were also examined, and four gnathostomes-two males and two females-were found in the stomach wall of one of the four R. surifer and one female of the same gnathostome in one of the two R. r. tiomanicus. The worms were parasitic in separate outpouchings of the stomach wall, the anterior part of the body being buried with the rest of the body free in the lumen of the stomach. The infected R. surifer was trapped on Ulu Lalang Peak, and the R. r. tiomanicus was on Gunong Kajang. The worms were preserved in 70% ethanol, and the four specimens from R. surifer were sent to the senior author for identification. Gnathostoma malaysiae sp. n. (Figs. 1-4) In worms preserved in liquid, posterior third of body swells, because cuticle is loosely connected with subcuticle (Fig. 1). Headbulb with about nine rows of hooklets. Whole body covered with cuticular spines of various shapes (Fig. 2). Spines in a few rows immediately behind headbulb usually single or two-toothed (A); rapidly becoming threetoothed, measuring about 100 (u in length, with middle tooth longer than others. Part B of the body covered with this type of spines. On part C three-toothed spines gradually change into fourtoothed ones posteriorly, and part D, almost half of the slender part of the body, is covered with fouror five-toothed, and sometimes with sixtoothed spines. At beginning of swollen part of body (E) spines suddenly diminish in length, and