A new species, Trypanosoma (Herpetosoma) aunawa, is described from the insectivorous bat Miniopterus tristris (family Vespertilionidae), from a cave in New Guinea. Details are also given of trypanosomes from the gut of a terrestrial leech, Philaemon sp., which feeds on M. tristris in the cave. It is suggested that the leech might transmit the trypanosome infection. This is the first time that a nonarthropod has been suspected of being involved in the transmission of a bat trypanosome. Constantine (1970) states that 19 species of trypanosomes have been reported from 52 species of bats, representing 10 families. Unfortunately he does not list them. Gittleson and Hoover (1969a) cite much of the literature on trypanosomes in bats, and list 14 species of trypanosomes and their hosts. At least four additional species are known from bats, viz.: T. hipposideri Mackerras, 1959; T. pifanoi Marinkelle and Duarte, 1968; T. pteropi Breinl, 1913; T. thomasi Lips and Rodhain, 1956. Constantine (1970) quotes experimental infections of several other species of trypanosomes in bats. Additional records of natural infections are given by Anciaux de Faveaux (1958), Berghe et al. (1963), Bray (1964), Deane (1964), Deane and Sugay (1963), Dias (1936), Dissanaike (1963), Gamham et al. (1971), Gittleson and Hoover (1969b), Goedbloed et al. (1964), Heisch and Gamham (1953), McConnell and Correa (1964), Marinkelle (1966), Reichenow (1953), Sandosham (1967), Wenyon (1926), and Zeledon and Vieto (1957, 1958). To date, all experimental and suspected vectors of bat trypanosomes have been arthropods. They include mites, blood sucking bugs of the families Cimicidae, Reduviidae, a tick, a flea, mosquitoes (Aedes spp.), and Phlebotomus sp. (Wenyon, 1926; Berghe et al., 1963; Gittleson and Hoover, 1969a; Constantine, 1970; McConnell and Correa, 1964). Some of these cases involved the development of trypanosomes in experimentally infected arthropods which probably do not act as vectors in Received for publication 16 February 1973. * Present address: Institute of Advanced Education, Warrnambool, Victoria, Australia 3280. nature. In other cases an arthropod has been assumed or suspected to be a vector because trypanosomes have been found in it, and it lives in close association with a particular bat which is naturally infected with trypanosomes. This paper describes Trypanosoma aunawa from an insectivorous bat, Miniopterus tristris, which lives in Javarere Cave, Papua New Guinea. Ten species of bats live in the cave, but M. tristris is the only one that has so far been found infected with trypanosomes. Trypanosomes are also described from a leech, Philaemon sp., which lives in the cave. This leech feeds on M. tristris in nature and may act as an intermediate host of T. aunawa. These observations are of some interest because all the literature on the transmission of bat trypanosomes provides evidence for, or suggests transmission by, arthropod vectors. Indeed this is one of the few cases where a leech is suspected of being involved in the transmission of a mammalian trypanosome. MATERIALS AND METHODS All material described in this paper is from Javarere Cave, a large limestone cave, situated in mountainous rain forest about 2 hr walk from Javarere Plantation (called Iawarere on old maps). This plantation and the adjacent Daradai Plantation are on the Musgrave River, at the end of the road from Sogeri, about 40 miles from Port Moresby. Maps and descriptions of the cave are available in the Reports and Journal of the Port Moresby Speleological Society (1960-63). A few hundred feet from the entrance there is a large cavern, from which two passages run; one is dry, the other runs downhill along a creek bed for perhaps a quarter of a mile. It contains running water at all times of the year. The ceiling of the creek passage varies considerably in height: in some places it is only a few feet; in others it is 30 or more feet high.