Proechimys Guyannensis Research Articles

Use of tooth impressions to identify and age live Proechimys guyannensis and P. cuvieri (Rodentia: Echimyidae)

A technique whereby impressions of the cheekteeth were used to identify and age live Proechimys guyannensis and P. cuvieri is presented and tested. Based on tooth eruption and occlusal surface wear, 15 age classes were defined. Used in concert with a body measurement, measurements of the length of the toothrow and age class allowed almost all live individuals of the two species to be distinguished. The relationship between mean cheektooth length and hind foot length was most useful for distinguishing relatively old individuals, whereas the relationship between hind foot length or head‐plus‐body length and toothrow age class was most useful for distinguishing younger individuals. Mean eye lens weight of P. guyannensis increased with toothrow age class, suggesting that the toothrow age classes successfully measured relative age. Individuals of P. guyannensis in lower age classes had juvenile or subadult pelage and did not show signs of reproductive activity, whereas individuals in higher age classes had adult pelage and approximately 50% showed signs of reproductive activity. In the central Amazon, P. cuvieri was found to be proportionally more abundant relative to P. guyannensis in early‐successional and edge‐dominated habitats.

Ectoparasitos de pequenos mamíferos da Ilha de Maracá, Roraima, Brasil. II. interação entre ectoparasitos e hospedeiros.

Indices globais pulicidianos, anoplurianos, malofagianos e acarianos foram determinados em mamiferos capturados na Ilha de Manacá, Roraima, Brasil, no periodo de, novembro de 1987 a fevereiro de 1989.Tendo-se em vista os valores limites ou criticas atri-buidos aos indices pulicidianos, propostos como medida complementar de vigilância epide-miológica para peste, alguns, roedores silvestres poderiam ter estado expostos a esta in-fecção. O indice global foi de 11,5e a pulga prevalente foi Polygznis klagesi klagesiobservado na estação seca. Os números máximos de ectoparasitas por hospedeiros foram: 244 para Prorchimys guyannensis, 193para Prorchimyssp. e 108 para Bolomys sp. As espéciescom indices de infestação mais elevados fonam P. klagesi klagesiem Peoechimyssp.; Glíricolasp. n., Tur apicalise Tur aymaraem P. guyannensis.infestações simples foram de mais prevalentes, enquanto as duplas e as outras múltiplas foram equivalentes. Com exceção deProechimyssp., todas as espécies de hospedeiros apresentaram infestações simples. Apenas Laelaps dearmasie Gliricola porcelliocorreram em infestações iso-ladas.

Distribution of Histoplasma capsulatum in Amazonian wildlife.

In a survey of 296 sylvatic animals captured from virgin forests in the north-eastern and south-western Amazon of Brazil, Histoplasma capsulatum was isolated, via the indirect hamster inoculation method, from the liver and spleen of four common opossums Didelphis marsupialis and two pacas Agouti paca. The infected animals did not show any clinical symptoms or histopathology. The known Amazonian mammalian species with natural histoplasmosis now total five, the previously reported species being the spiny rat Proechimys guyannensis, the two-toed sloth Choloepus didactylus and the nine-banded armadillo Dasypus novemcinctus.

Leishmaniasis in Brazil: XX. Prevalence of “enzootic rodent leishmaniasis” ( Leishmania mexicana amazonensis), and apparent absence of “pian bois” ( Le. braziliensis guyanensis), in plantations of introduced tree species and in other non-climax forests in eastern Amazônia

In Amazonian Brazil most human leishmaniasis is due to Leishmania braziliensis s.l. and is acquired during the clearing of primary climax forest. One of the largest deforestation projects has taken place on the JARI property where plantations of exotic tree species are grown for paper pulp. The ability of the regional leishmaniasis enzootics to invade plantations was investigated. CDC light-trap catches indicated the phletobomine vectors of Le. b. guyanensis (causing “pian bois” in man) to be very scarce in JARI plantations compared to native-forest controls. It is concluded (drawing on other observations) that the vectors of “pian bois” are unlikely to thrive in any secondary forest. In contrast, catches from mammal traps and rodent-baited (Disney) traps demonstrated the presence in JARI plantations of infected Proechimys guyannensis and large populations of Lutzomyia flaviscutellata, respectively the major rodent reservoir and sandfly vector of Le. mexicana amazonensis. Alone amongst the local vectors of human cutaneous leishmaniasis, Lu. flaviscutellata is adapted to non-climax forests (primary or secondary, natural or man-made; synopsis given). It is predicted that the public health importance of Le. m. amazonensis is unlikely to diminish following the development of Amazônia. This is worrying because ca. 30% of Le. m. amazonensis infections in man cause highly-disfiguring, incurable “diffuse cutaneous leishmaniasis”.

Leishmaniasis in Brazil: XVI. Isolation and identification of, Leishmania species from sandflies, wild mammals and man in north Pará State, with particular reference to L. braziliensis guyanensis causative agent of “pian-bois”

A total of 125 wild mammals (14 different species) were examined for evidence of infection with Leishmania in an area of primary forest highly endemic for “pian-bois”, due to Leishmania braziliensis guyanensis, in north Pará State, Brazil. Parasites isolated were characterized biologically, and biochemically on enzymic profiles. L. b. guyanensis was isolated from the viscera of one lesser anteater ( Tamandua tetradactyla) and one opossum ( Didelphis marsupialis), and the skin of one rodent ( Proechimys guyannensis). The isolates were indistinguishable from 10 others previously made from the sandfly vectors Lutzomyia umbratilis (five) and Lu. whitmani ∗ ∗ Lu. is used as the abbreviation for Lutzomyia to avoid confusion with that of L. for Leishmania. (five), and nine isolates from field-workers who became infected during these studies. Leishmania mexicana amazonensis was obtained from the skin of 21 animals, including three species of opossums ( D. marsupialis, Philander opossum and Metachirus nudicaudatus) and two species of rodents ( Proechimys guyannensis and Dasyprocta sp.). A peripylarian Leishmania isolated from the viscera of two armadillos ( Dasypus novemcinctus) was shown to be different, biologically and biochemically, from L. b. guyanensis and L. m. amazonensis. Four other isolates of Leishmania, from the rodents Rhipidomys leucodactylus (one) and P. guyannensis (three) have yet to be characterized owing to their very poor growth in both hamster skin and in vitro culture: they appear closest, however, to L. braziliensis braziliensis. The complexity of Amazonian leishmaniasis is discussed, and attention drawn to the importance of edentates as reservoir hosts of some leishmahias in the New World. Whereas L. mexicana subspecies appear largely restricted to the skin of their natural hosts, subspecies of L. braziliensis are commonly found in the viscera.

The opossum, Didelphis marsupialis (Marsupialia: Didelphidae), as a reservoir host of Leishmania braziliensis guyanensis in the Amazon Basin of Brazil

A total of 52 opossums (six species) were examined for evidence of infection with Leishmania in three different areas of forest near Manaus, Amazonas State, Brazil. No infections were detected in 27 opossums from a region of relatively undisturbed forest, including specimens of Didelphis marsupialis (18), Metachirus nudicaudatus (four); Monodelphis brevicaudata (one), Marmosa cinerea (two), M. murina (one) and M. parvidens (one). Of 15 D. marsupialis captured from a biological reserve, much disturbed by man, three were infected with L. braziliensis guyanensis: isolations were made from the skin of two of the animals, and from the viscera of the third. The isolates were biologically and biochemically indistinguishable from one isolate of L. b. guyanensis made from man and two from the sandfly vector Lutzomyia umbratilis from the same area. Two of eight D. marsupialis and both of two M. cinerea from another area of virgin forest used for army manoeuvres were infected with Leishmania mexicana amazonensis: the parasite was in all four cases isolated from normal skin. Five of nine specimens of Proechimys guyannensis, from the vicinity of Manaus, were also infected with L. m. amazonensis. A further 13 mammals (eight species) were negative for Leishmania. The importance of opossums as a reservoir of L. b. guyanensis is discussed. Although they may play only a minor role in virgin forest which is undisturbed by man, opossums ( D. marsupialis) may become a significant reservoir of infection where man's activities have eliminated the major reservoir—which has yet to be incriminated.

The chromosomes of spiny rats, proechimys trinitatis, from Trinidad and Eastern Venezuela (Rodentia, Echimyidae)

A detailed description of the karyotype of Proechimys trinitatis, (2n = 62, FN = SO), based on specimens from Trinidad, is given. It differs from the karyotype of Proechimys guyannensis (2n = 40) which is interpreted as an indication of the need of giving full species status to P. trinitatis. It also differs from the karyotype of P. urichi, a montane form living in Eastern Venezuela, and it is remarkably different from the karyotypes of members of the superspecies P. guairae from north-western and north-central Venezuela. Specimens from a sample of Cachipo, in the lowlands of Monagas State, proved to have a karyotype identical to that of the studied specimens of P. trinitatis from Trinidad. This is interpreted as an indication that P. trinitatis is also represented on the continent. Differences in size and in cranial characters of the Venezuelan specimens uggest hat the Cachipo sample might be separated as a distinct subspecies of P. trinitatis. ability is interpopulational (Reig et al., 1979). Therefore, when karyotypic differences are large enough as to imply postzygotic reproductive isolation by a high level of gametic aneuploidy in the F, hybrids (Capanna et al., 1977; Reig et al., 1979) these differences make a good tool for species recognition, even when this recognition is hard to make on morphological grounds. Consequently, chromosome investigations may contribute to the understanding of the confusing systematics of this genus, and help to gain further knowledge on the role played by karyotypic rearrangements in the speciation process, a subject which is becoming a point of primary attention in modem theory of speciation (White, 1978). We now report the karyotype of Proechimys trinitatis (Allen & Chapman) 1893, the type species of Proechimys (Allen, 1899), but which has been alleged (Ellerman, 1940) not to be separable at the species level from the earlier proposed Proechimys guyannensis (E. Geoffroy) 1803.

The Perfect State of Microsporum Amazonicum

Six cultures of Microsporum amazonicum were recently isolated from the hair of six spiny rats (Proechimys guyannensis) trapped near the city of Belem, Brasil. When the six isolates were paired with each other in all possible combinations on soil-hair plates, eight of 15 pairs developed fertile ascocarps. Based on the morphology of the gymnothecia, the perfect state was classified in the genus N annizzia. The perfect state was described and contrasted with the other species of N annizzia.(AU )

Endoparasitic Chiggers: VIII. The Intradermal Genus Intercutestrix Brennan and Yunker, 1966, and Three New Species (Acarina: Trombiculidae)

Intercutestrix is redescribed, and the new species I. exigua off Proechimys semispinosus and Sigmodon hispidus, Venezuela, I. incomitata off Hoplomys gymnurus, Colombia, and I. pisinna off Proechimys guyannensis, Venezuela, are described. A key to the 5 included species is given. Three new species of the Neotropical intradermal genus Intercutestrix have prompted a generic redescription and assay of promising structural features for ready identification of the minute larvae. Contributing to this study are two species (I. exigua and I. pisinna) collected in Venezuela under the supervision of Dr. Charles 0. Handley, Smithsonian Institution, and Dr. Vernon J. Tipton, Brigham Young University, and one species (I. incomitata) collected in Colombia by Mr. Kjell von Sneidem under the direction of the Field Museum of Natural History. Intercutestrix Brennan and Yunker Intercutestrix Brennan and Yunker, 1966, p. 237. Neotropical trombiculine larvae, intradermal parasites of small mammals, principally rodents of the family Echimyidae. Broad ellipsoidal to subcircular when engorged. Scutum arcuate, considerably wider than long, with shallow sinuous margins. Five scutal setae, anteroand posterolaterals approximate, the latter far anterior to the sensillary bases. Sensillae caducous, known only in one specimen of I. mondolfii where they are broad obovate and moderately setulose. Eyes minute, 2/2 in an indistinct plate, the posterior pair sometimes evanescent. Cheliceral blade small with tricuspid cap. Galeal seta nude. Palpal tibial claw slender, trifurcate; palpal tarsus with 4 branched setae and a tarsala. Leg segmentation 7-6-6; legs with 2 genualae I, no genuala II and III, a tibiala Received for publication 2 July 1973. * This work was supported in part by Department of the Army Contract DA-49-193-MD-2788 with the Smithsonian Institution (Ecology and distribution of mammalian ectoparasites, arboviruses, and their hosts in Venezuela). t U. S. Department of Health, Education, and Welfare, Public Health Service, NIH, NIAID, Rocky Mountain Laboratory, Hamilton, Montana 59840. $ Department of Zoology, Brigham Young University, Provo, Utah 84601. III, no mastisetae, a suband abbreviate parasubterminala, microtarsala I lateroproximad of tarsala I; coxae unisetose. Type species: Euschongastia tryssa Brennan and Jones, 1961. Referred species: Intercutestrix mondolfii Brennan and Yunker, 1969, I. exiguia sp. n., I. incomitata sp. n., and I. pisinna sp. n. Species of Intercutestrix seem to prefer rodent hosts of the family Echimyidae, particularly of the genus Proechimys, although they have been recorded from other rodents and opossums. The minute larvae are rather elusive because of their intradermal habitat where they occur singly, almost completely enclosed in a keratinous cyst, and are found ventrally on the host only by thorough and specific examination (Brennan and Yunker, 1969). Consequently, samples resulting from general chigger collecting are most often small and inadequate for precise and conclusive taxonomic study. Disregarding other structural characters, the five included species are separable by form, size, and arrangement of dorsal setae. The scutum, in the almost invariable absence of sensillae, and setation of the appendages are not remarkable, and offer little aid in specific identification. Figures of scutum and specialized setae of legs were given by Brennan and Jones (1961) for I. tryssa and by Brennan and Yunker (1969) for it and I. mondolfii. Thus, an illustration of scutum and specialized leg setae for only one new species, I. exigua, will suffice here. Key to larvae of Intercutestrix 1. Second posthumeral row with 10 setae (Peru) -.-. --------.-.......tryssa Second posthumeral row with 6 setae .---2 2. Palpal setal formula B/B/BBB, dorsal setal formula begins 2-10 (Colombia) ----)-----...--...... -. .......incomitata

Revival of Vanidicus Brennan & Jones, 1961, descriptions of two new species of the genus from Venezuela, and notes on related taxa (Acarina: Trombiculidae).

Vanidicus Brennan & Jones, 1961, synonymized with Pseudoschoengastia by Geest & Loomis (1968), is redescribed and restored to generic status. V. chalepus off Oryzomys albigularis and V.jojosti off Proechimys guyannensis, Venezuela, are described as new. The type species, V. tricosus, is briefly redescribed and descriptive notes of related forms are given.

Two new Venezuelan chiggers of the genus Polylopadium (Acarina: trombiculidae).

Polylopadium chaetolecanium, n. sp. off Proechimys guyannensis, Sucre, and P. tricholecanium, n. sp, off Proechimys sp., Falcon, are described and figured.

Three New Chiggers from Spiny Rat, Proechimys guyannensis, in Northern Brazil (Acarina: Trombiculidae)

Parasecia orphana , Microtrombicula brachytrichia , and Trombicula (s.l.) ignota are described. All specimens were collected from Proechimys guyannensis in the vicinity of Belem, Para, Brazil.

Two New Genera and a New Species of Neotropical Chiggers (Acarina: Trombiculidae)

Described are AITKENIUS and QUADRASETA to receive certain species originally in Euschoengastia . Keys to included species are given and A. vellosus , n. sp., holotype off Proechimys guyannensis from northern Brazil, is described.

Colicus, a new neotropical genus with descriptions of two new species and a key to included species (Acarina: Trombiculidae).

Colicus , new genus, is described to receive new species and certain species originally referred to other genera. New species described are: C. icomi off Proechimys guyannensis from northeastern Brazil and C. minicolus off Myotis sp., Colombia.

Leishmaniasis in Brazil: I. Observations on enzootic rodent leishmaniasis—incrimination of lutzomyia flaviscutellata (mangabeira) as the vector in the lower amazonian basin

During observations on a focus of enzootic leishmaniasis of rodents in the Utinga Forest, Belém, Pará, Brazil, active infections were encountered in 16 (17·98%) of 89 Oryzomys capito examined. Cutaneous lesions were restricted to the tails of these animals, and spontaneous recovery leaves characteristic scarring. Taking such scars into account, it is estimated that as many as 70% of the Oryzomys population may experience infection at some time during their lives. Leishmania were isolated from 3 specimens of Proechimys guyannensis captured in the same forest area. In addition to obvious lesions on the tail and foot, parasites were isolated from apparently normal ear tissue. The strains of Leishmania from Oryzomys and Proechimys appear to be identical. Insect traps were baited with Oryzomys, Proechimys and other rodents. During a period of 4 months they captured 2,774 phlebotomine sandflies, of which 2,731 were Lutzomyia flaviscutellata Mangabeira. In contrast, only 5 specimens (0·69%) of Lu. flaviscutellata were encountered among 724 sandflies caught of human bait during the same period, in the same area. Leptomonads were found in 8 of 2,706 Lu. flaviscutellata dissected (0·29%). Inoculation of these flagellates into hamsters produced typical leishmanial lesions in 6 cases. We conclude that Lutzomyia flaviscutellata is the major vector of the Leishmania sp., among Oryzomys and Proechimys in the Utinga Forest area of the Lower Amazon Region. Similarities are noted between this parasite of Brazilian rodents and Leishmania mexicana of rodents and man in Central America.

Icoaraci, a New Virus Related to Naples Phlebotomus Fever Virus.

SummaryIcoaraci, a newly recognized virus, has been isolated on 8 occasions from forest rodents captured near Belem, Para, Brazil. At least 7 of the isolations were from Proechimys guyannensis oris. The virus is related to Naples phlebotomus fever virus by hemagglutination-inhibition testing. Hemag-glutination-inhibiting antibody to Icoaraci virus is prevalent in small forest animals but has not been found in human inhabitants of Belem.

Four New Chiggers (Acarina: Trombiculidae) From Rodents of the Epidemic Area of Bolivian Hemorrhagic Fever

Miyatrombicula arandiai n. sp. and Euschoengastia johnsoni n. sp. are described from Calomys callosus in Beni, Bolivia. Euschoengastia kunsi n. sp. and E. mackenziei n. sp. are described from Proechimys guyannensis, same locality. Additional host records are given.