Phyllostomus Hastatus Research Articles

Comparative auditory neurophysiology of neotropical bats employing different echolocation signals

1. Five species of neotropical bats, which emit echolocation pulses different than those employed by bats previously studied, were investigated in an attempt to find corresponding differences in mechanisms of neural analysis. Evoked potentials were recorded from the posterior colliculi and more peripheral levels in anesthetized specimens. 2. Each species was found to be most sensitive in approximately the same frequency range it uses in its emitted pulses: Chilonycteris rubiginosa at 63 kc/s, Pteronotus suapurensis at 50 kc/s, Saccopteryx bilineata at 42 kc/s, Phyllostomus hastatus at 50 kc/s, and Carollia perspicillata at 80 kc/s. Sensitivity was especially sharply “tuned” in the bats employing predominantly constant frequency pulses (Chilonycteris and Saccopteryx). 3. Chilonycteris, Saccopterys and Pteronotus have prominent evoked potential responses to the end of a tone pip. In Chilonycteris and Saccopteryx these “off”-responses are extremely sharply tuned to a 2–5 kc/s frequency band centered just below the frequency of greatest sensitivity of the “on” response. The presence of an “off”-response appears to be correlated with the use of long, predominantly constant frequency pulses. 4. The rate of recovery of responsiveness following an initial signal varied, being rapid at the level of the colliculus in Phyllostomus and Carollia (100% in 2–3 msec, slight supranormal responsiveness, and no subsequent depression), also rapid in Pteronotus, (but with an unusual degree of facilitation of responsiveness at intervals of 1–2 msec, followed by 5–10 msec of deep depression), and comparatively slow in Chilonycteris and Saccopteryx (full recovery in 10 msec or more). 5. In bats using long orientation pulses which overlap with returning echoes (Chilonycteris and Saccopteryx), the “off”-responses are found to provide a more visible record of the presence of echoes and their time of arrival than do the “on”-responses. 6. Chilonycteris respond to the orientation pulses of other Chilonycteris with prominent “off”-responses, which apparently are evoked by the termination of the constant frequency portion of each pulse rather than the downward FM sweep. 7. Phyllostomus and Chilonycteris are sharply sensitive to changes in signal angle, Pteronotus is moderately so, and Saccopteryx and Carollia are relatively insensitive to angle at the level of the colliculus. In Saccopteryx and Carrollia the auditory nerve response is more sharply sensitive to angular change of the signal. 8. In several species, but most prominently in Pteronotus, large DC potentials, of the same duration as the signal, were recorded in the vicinity of the cochlea and VIII nerve. These potentials were probably “summating potentials” and sometimes showed reversal of polarity with changes in signal frequency. 9. In one preparation (Pteronotus), a DC potential was seen that was apparently contralateral in origin, had a latency 1 msec longer than the ipsilateral “summating potential”, and showed adaptation suggestive of a neural origin. It is suggested that a direct neural pathway between the two ears may exist. 10. It is concluded that species differences in response patterns are at least in part a result of evolutionary adaptation governed by the type of emitted orientation sounds employed.

Endoparasitic chiggers. V. New genera, species and records from Venezuela and Brazil (Acarina: Trombiculidae).

Described are 2 new intranasal genera, Nasicola and Rhinibius , monotypic respectively for N. annereauxi , n. sp. Off Phyllostomus hastatus , Venezuela, and R. tamandua , n. sp., holotype off Tamandua tetradactyia , Brazil. A new intradermal species. Interculestrix mondolfii holotype off Prechimys guyannensis , Venezuela, is described with records from Panama and Colomiba included. In addition, distributional data are given for Kymocta faitkeni Brennan and K. inca Brennan & Jones, newly recorded in Venezuela. The original description of K. faitkeni has been modified.

Control of Behavior by the Location of an Auditory Stimulus

The control of behavior by the location of tone bursts was investigated in rats and in bats of the species Phyllostomus hastatus. The apparatus consisted of an enclosure with two keys, two loudspeakers (in different locations in the animal's azimuth), and a dipper feeder. On each trial, the animal was exposed to tone bursts from either one or the other of the two speakers and a response on the appropriate key (correct response) was reinforced with food. When tone bursts have a rapid rise time (approximately 0.2 msec), location is a dominant feature of the stimulus: The discrimination is acquired within the first session and the stable-state level is maintained at near 100% correct responses. When the tone bursts do not have prominent transient characteristics (rise time of 1 msec or more) the location discrimination is acquired more slowly (if at all) and the stable state level is low (80%–90% correct responses). [Supported by National Science Foundation.]

Visual obstacle avoidance by echolocating bats

Evidence is presented that two species of echolocating bats, Carollia perspicillata and Phyllostomus hastatus, while in flight in subdued daylight can visually detect and avoid 30-cm wide strips of white cloth suspended across their flight space. Bats deafened with earplugs avoided the cloth strips significantly better than did individuals that were both deafened and blindfolded. Blindfolding alone did not impair the bat's ability to negotiate these obstacles. Control experiments indicate that loss of vision—rather than any possible secondary effects of the various treatments—was responsible for the differences in behaviour and obstacle avoidance scores between deaf and deaf-blind bats. Deafened bats showed striking differences from non-deafened individuals in the pattern and amplitude of their orientation cries emitted as they approached the strips of cloth. Whereas normal or blind bats increased their pulse repetition rate when approaching the barrier, deaf or deaf-blind individuals maintained high repetition rates and pulse intensities which did not change as the barrier was approached, indicating that it was not detected. Certain limitations of echolocation and its possible supplementation by vision are discussed. It is suggested that vision may provide a passive surveillance system for resting bats and thus reduce the energy expenditure associated with sound production and the scanning of the environment for echoes. The range limitations of acoustic orientation may make visual detection of familiar landmarks especially useful to these frugivorous bats when finding their way to and from feeding sites.

Karyotypes of Seven Species of Brazilian Bats

SUMMARYThe chromosome complements of the seven species studied are as follows:Phyllostomus hastatus (2 n=32) has 13 pairs of metacentric or submetacentric and one pair of acrocentric autosomes. The X is a submetacentric and the Y is minute. Phyllostomus discolor (2 n = 32) has all its autosomes metacentric or submetacentric. The X is submetacentric. Chrotopterus auritus (2 n = 28) has all its autosomes metacentric or submetacentric. The X is a me dium submetacentric and the Y is minute. Carolila perspicillata (2 n = 20, 21) has 9 pairs of metacentric or submetacentric autosomes, all distinguishable from each other. The X is submetacentric, the Y1 is a medium acrocentric and the Y2 is a small acrocentric. Artibeus lituratus (2 n = 30, 31) has all its autosomes metacentric or submetacentric. The X is a submetacentric, the Y1 is a acrocentric and the Y2 is a small acrocentric. Desmodus rotundus (2n=28) has all its autosomes metacentric or submetacentric. The X is a submetacentric and the Y is minute. Noctili...

Echolocation: Processing of Range Information by Bats

Echolocating bats of the species Eptesicus fuscus and Phyllostomus hastatus were trained to respond to the nearer of two targets in simultaneous discrimination experiments. The acuity of depth or range perception by sonar was measured on a series of range differences from 10 cm down to zero at absolute ranges of 30 and 60 cm. The minimum detectable range difference (75% threshold) was 11 to 13 mm for both species. The shapes of the range threshold curves corresponded roughly to the shapes of the envelopes of the autocorrelation functions of the sonar cries of the bats, even when the envelopes exhibited several maxima. The results suggest that these bats may extract range information from echoes by pulse compression. The matched filter for the sonar receiver may be a correlation network in the bat's auditory nervous system.

Trypanosoma pifanoi n. sp. from Colombian bats.

SYNOPSIS. A new large trypanosome was found in the blood of 19 Artibeus lituratus and 2 Phyllostomus hastatus bats. The monomorphic trypanosome resembles Trypanosoma megadermae in some respects, but differs from it in that it is larger and has a short flagellum, both extremities are very tapered, the kinetoplast is very close to a small nucleus and there is a greater distance between the kinetoplast and the posterior extremity of the body. In diphasic blood‐agar cultures there is a great variety of odd multiplication forms not described from other trypanosome cultures, but some simulate T. cruzi. This trypanosome is not capable of infecting mice, tissue culture cells, Carollia perspicillata bats, or triatomids, but is able to infect A. lituratus bats. Culture forms of the trypanosome inoculated intra‐coelomically are pathogenic for several species of triatomids, and multiply in the hemolymph of Rhodnius prolizus, often producing forms similar to crithidiae of T. rangeli. Culture forms of the trypanosome seem to have common antigens with T. cruzi. This new species is described as Trypanosoma pifanoi.

Temperature regulation in some Brazilian phyllostomid bats

1. 1. Body temperature cycles were measured in six frugivorous bats: Phyllostomus hastatus; P. discolor; Artibeus lituratus; A. jamaicensis; Sturnira lilium and Glossophaga soricina. 2. 2. Minima werer 34·5, 35·3, 36·4, 36·4, 37·1 and 37·2°C at 14.00 hr and maxima were 36·4, 38·2, 38·8, 39·1, 39·1, 39·3 and 39·5°C at 11.00 hr (respectively). The cycle amplitude correlated positively with increasing body size. 3. 3. In daily cycle and response to cold, phyllostomid bats resemble other mammals rather than thermolabile insectivorous bats. A few low temperatures were observed during the day (29–33°C). 4. 4. A small insectivorous species ( Mollossus major) exhibited diurnal torpor with temperatures falling to within 2°C of ambient and showing maxima at dusk and dawn.

The homing ability of the neotropical bat Phyllostomus hastatus, with evidence for visual orientation

Summary o 1. The neotropical bat Phyllostomus hastatus studied in Trinidad, West Indies, showed a superior homing performance to any previously reported for bats of temperate latitudes. In one night 94 per cent of seventy-four returned from 3 to 6 miles, 57 per cent of 257 from 7 to 21 miles, and 26 per cent of 112 at 25–33 miles. None of fifty returned the first night from 39 to 40 miles, but 12 per cent were observed over the next several days. 2. On one occasion two out of five bats returned from 6 miles within 1 hr and after some releases at 15–20 miles 40 per cent of the bats returned within 3–4 hr. The homing performance was not significantly affected by intervening mountains of 2000–3000 ft or by up to 10 miles of open water. Bats released 1 mile apart homed as well or better than those released in groups. 3. Blindfolded P. hastatus flew normally and appeared to live normal lives for several days. From distances of 5–8 miles a considerable number of blindfolded bats homed during the first night. The data do not suffice to demonstrate whether or not there was a significant difference in homing performance from these distances between blindfolded bats and controls equipped with goggles similar to the blindfolds except for clear plastic windows over the eyes. But at 15 to 20 miles none of thirty-six blindfolded bats returned in one night with their eyes effectively covered, even though half those equipped with goggles did so. 4. It thus seems likely that within familiar territory these bats can find their way without the need for vision, but that at 15–20 miles they are severely handicapped if deprived of visual orientation. One simple explanation would be use of the northern range of mountains for visual piloting.

Histoplasma Capsulatum in Fecal Contents and Organs of Bats in the Canal Zone

Summary Histoplasma capsulatum was recovered from tissues of 62 of 623 bats collected in the Canal Zone and the Republic of Panama. The culturally positive species were Carollia perspiculata, Chilonycteris rubiginosa, Micronycteris megalotis, Molossus major, Glossophaga soricina and Phyllostomus hastatus. The fungus was isolated repeatedly from the feces of Chilonycteris rubiginosa and Micronycteris megalotis. Quantitative estimates of H. capsulatum in feces revealed that up to 2000 fungi could be demonstrated in the fecal contents at any one time. The sources of the positive cultures were lesions readily demonstrable in the intestinal mucosa. The importance of the presence of the fungus in intestinal contents as it relates to the seeding of the soil and infection in man and other genera of bats is discussed.

Sobre um Schizotrypanum dos morcegos Lonchoglossa ecaudata e carollia perspicillata do Brasil

Fica assinalada a infecção natural dos Phyllostomideos Lonchoglossa ecaudata e Carollia perspicillata no Estado de Minas Gerais e na cidade do Rio de Janeiro, Brasil, por um Schizotrypanum. 2) em ambos os morcegos as formas de tripanosoma apresentam morfologia idêntica, caracterisada principalmente por suas pequenas dimensões (15µ) e pelo núcleo localisado muito próximo ao extremo anterior do corpo. 3) Tais características morfológicas são muito visinhas, sinão idênticas, ás do Schizotrypanum vespertilionis (Battaglia), e distinguem o parasito em estudo do Schizotrypanum cruzi humano, de um Schizotrypanum do morcego Carollia perspicillata da Venezuela (= T. phyllostomae Cartaya?) e do Schizotrypanum do morcego Phyllostomus hastatus do Brasil. 4) Em córtes de coração de Lonchoglossa ecaudata foram encontrados parasitos com a morfologia de leishmania. 5) Xenodiagnosticos realisados com Panstrongylus megistus, Triatoma infestans e Rhodnius prolixus, em morcegos com tripanosomas no sangue ao exame a fresco, resultaram negativos. 6) Em amplas as espécies de morcegos, no Rio de Janeiro, foi encontrado tambem um grande tripanosoma do grupo megadermae, parecido com o Trypanosoma heybergi Rodhain do morcego africano Nycteris hispidus. Em C. perspicillata da mesma cidade foi verificada tambem a infecção pela Bartonella rocha-limai Faria & Pinto, e tambem a presença de microfilarias no sangue. No rim de C. perspicillata de B. Constant encontramos fórmas esquisogonicas de um protozoário.

Observations on the Carnivorous Habits of the Spear-Nosed Bat, Phyllostomus Hastatus Panamensis Allen, in Panama

Observations on the Carnivorous Habits of the Spear-Nosed Bat, Phyllostomus Hastatus Panamensis Allen, in Panama