Sciency Thoughts: Two new species of Pinworms from Sulawesi Soft-furred Rats.

Tuesday 30 December 2014

Two new species of Pinworms from Sulawesi Soft-furred Rats.

Pinworms, Oxyuridae, are parasitic Nematodes infecting the digestive tracts of Mammals. They have short life cycles, typically undergoing several generations in a year, with eggs being released in the host’s faecal matter to infect new hosts. Some species of Pinworm appear to be quite cosmopolitan, infecting a range of hosts, but most species have a close relationship with a specific host species and rarely cross-infect other species.

In a paper published in the Raffles Bulletin of Zoology on 18 September 2014, Kartika Dewi of the Zoology Division at Museum Zoologicum Bogoriense, Hideo Hasegawa of the Department of Biology at OitaUniversity and Mitsuhiko Asakawa of the Department of Parasitology at Rakuno Gakuen University describe two new species of Pinworms from Sulawesi Soft-furred Rats, Eropeplus canus, trapped at Lambanan in the South Sulawesi Administrative District. The Sulawesi Soft-furred Rat is an indigenous species to Sulawesi (i.e. found nowhere else), known only from a few mountainous localities (altitudes between 1800 and 2300 m) and considered to be Vulnerable under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species. Both of the new species are placed in the genus Syphacia, seven species of which have previously been recorded from Indonesia; the cosmopolitan Syphaciamuris, which infects a variety of Rats (Rattus spp.), plus four species infecting indigenous Rodents on Sulawesi and one species each infecting Rodents on Halmahera and Papua.

The first new species is placed in a new subgenus, Rumbaisyphacia, which is a combination of ‘rumbai’, an Indonesian word meaning ‘fringe’ and the name of the genus (i.e. ‘fringed Syphacia’) and given the specific name kumis, meaning ‘moustache’ in Indonesian; both names refer to a fringe of papillae around the mouthparts. The species is described from twenty two specimens, eleven of each species. The females are considerably larger than the males, at 3.21–4.12 mm as opposed to 1.51–1.72 mm.

Syphacia (Rumbaisyphacia) kumis, from Eropeplus canus in south Sulawesi, Indonesia. (1) male, lateral view; (2) cephalic end of male, apical view. Dewiet al. (2014).

The second new species is also placed in a new subgenus, Segienamsyphacia, from ‘Segienam’, which means ‘hexagonal’ in Indonesian, a reference to the mouthparts of the female, and given the specific name yuniae in honour of Yuni Apriyanti, who prepared the specimens for observation by SEM. This species is also described from eleven male and eleven female specimens. The females of this species are also bigger than the males (though not as much so as in Syphacia (Rumbaisyphacia) kumis) at 2.34–2.56 mm in the females and 1.00–1.25 mm in the males.

Syphacia (Segienamsyphacia) yuniae, from Eropeplus canus in south Sulawesi, Indonesia. (11) male, lateral view; (12) cephalic end of male, apical view. (18)Female, lateral view; (19) cephalic end of female, apical view. Dewi et al. (2014).

Dual infections of Pinworms are rare in Rodents, with most species having a single Pinworm parasite, and where more than one species is present this is generally thought to be an exceptional situation in which unhealthy animals have been opportunistically infected by non-specific parasites. However all of the Sulawesi Soft-furred Rats inspected were suffering from infections of both Pinworm species, and did not appear to be particularly unhealthy. Dewiet al. suggest that as additional resource partition by the parasites, with the Pinworms probably infecting different microhabitats of utilizing different nutrients.