Scanning electron microscope observations of Gongylonema neoplasticum and Heterakis spumosa, nematode parasites of an endemic murine rodent from Sulawesi

Sulawesi has unique mammalian fauna with high level of endemism. One of the endemic fauna in Sulawesi is Bunomys chrysocomus (Rodentia: Muridae). This study aimed to observed the nematode species parasitizing B. chrysocomus by using scanning electron microscope. Based on the observation nematodes obtained from gastric mucosa was Gongylonema neoplasticum Fibiger and Ditlevsen, 1914, while from the caecum was Heterakis spumosa Schneider, 1866. Both nematodes are cosmopolite nematodes which have wide host range and worldwide distribution. The detail morphology and taxonomic status of both nematodes from B. chrysocomus of Sulawesi will be presented here.


Introduction
Sulawesi, formerly known as Celebes, is the largest and oldest island within Wallacea. This island harbor many unique mammalian fauna with a very high level of endemism [1]. The murine rodents represent about 30% of the total mammalian species and approximately 52% of all the endemic species in this island [2]. Consequently, helminth parasites of murine rodents are also rich in this region.
Some researches stated that 60% of human diseases to be of zoonotic origin [3]. Nematoda parasites have ability for host shifting with potential effect for human and wildlife health. The interesting one is nematode parasites of murin rodents because some reports have been recorded for the human infection by these nematodes. For example, Cyclodontostomum purvisi, a nematode parasitic in the cecum of murines, has been recorded from human body [4]. A case of human infection with Rictularia was found in New York [5]. Moreover, human cases of angiostrongyloidiasis were reported from North Sumatra [6] and Java [7].
Specimens of Gongylonema neoplasticum (Fibiger and Ditlevsen, 1914) and Heterakis spumosa Schneider, 1866 were collected from gastric mucosa and caecum of Bunomys chrysocomus, an endemic murine of Sulawesi, respectively. The presence of both species as the parasite in B. chrysocomus in Sulawesi already reported by Purwaningsih and Dewi [8] and Dewi [9]. Furthermore, in this study, both nematode species were observed by using scanning electron microscopy (SEM

Materials and Methods
Heterakis spumosa and G. neoplasticum from Pakuli, Gumbara, Donggala, Central Sulawesi deposited in Museum Zoologicum Bogor were observed by SEM. SEM observation was done under a scanning electron microscope, type JSM 5310LV for detailed examination. Measurements were made by software ImageJ v. 1.51m9 software (NIH, USA). In order to measure the character, we also observed the nematode by using a light microscope Nikon SE100 with an ocular micrometer. Measurements (minimum, maximum, followed by mean in parentheses) were given in micrometers unless otherwise stated. For light microscopic study, nematodes were cleared in glycerine until sufficiently transparent for examination. For SEM study, specimens were fixed in glutaraldehyde, dehydrated through a series of ethanol and freeze-dried. Dried specimens were then coated with gold using standard techniques. General. -Anterior end bluntly rounded with terminal mouth (Fig. 2D). Three dome-shaped lips present. Two cephalic papillae at dorsal lip and one cephalic papilla at each sub ventral lips (Fig. 2B). Cervical alae well developed as long as body ( Fig. 2A). Amphids at sub ventral lips, same in side with cephalic papilla. Oesophagus divided into three part; short pharynx, cylinder oesophagus and a strong posterior bulb with valvular apparatus. Cuticle transversal striation smooth.

Gongylonematidae (Hall
Male 3.1.2. Remarks. The general morphology and measurements of H. spumosa in this study agree well with the previous studies [12,13]. Ribas et al. [12] observed H. spumosa from Cricetomys gambianus from Senegal, while del Rosario Robles [13] studied that species from R. norvegicus of Argentina. Both of studies observed H. spumosa by SEM but they did not report the presence of phasmid at the dorsolateral of caudal papilla at the tip of tail. This study support data that H. spumosa is a cosmopolitan nematode species that also can survive as the parasite in the endemic murine rodent.