Males of Bufo dombensis were observed calling late at night at Ongongo Waterfall in north-western Namibia. The analyzed advertisement calls differ distinctly from those of B. vertebralis, B. hoeschi and B, fenoulheti, indicating that all these taxa are separate valid species. Tadpoles raised from a breeding pair found at Ongongo showed the typical oral characters of southern African Bufo (1:1+1/3 keratodont formula, broad mental gap in oral papillae) but differed by some characters from tadpoles of other sympatric Bufo species.
A potential strategy for southern African small mammals to maximise reproductive success is to cue breeding activity to rainfall and subsequent Vegetative growth via a secondary plant compound such as 6-methoxybenzoxazolinone (6MBOA). This study investigated whether the sub-tropical rodent Saccostomus campestris utilised this compound to enhance reproductive activity. 6MBOA or control vehicle were injected into adult females and into peri-pubertal females under long day (LD) and short day (SD) photoperiods (adults n = 6 to 8; peripubertals n = 5 to 10/treatment). There was no significant effect of 6MBOA or photoperiod on uterine or ovarian masses nor on ovarian development in sacrificed animals, nor on age at vaginal opening of peri-pubertals. It was concluded that 6MBOA is not a major stimulant of reproduction in this species. Rather, we propose that seasonal breeding occurs in response to multiple environmental cues. This reproductive strategy and omnivory permit an opportunistic reproductive response to the unpredictable environment of the southern African region.
Three species of the rocky-shore inhabiting mite genus Amhyadesia Fain and Ganning 1979 (Acari, Astigmata, Hyadesiidae) were present in collections made across the extent of the southern African sub-continent, from Elandsbaai on the west coast to Inhambane (Mozambique) on the east coast. Two are new species, A. austafricana spec. nov. and A. elizabethensis spec. nov., and are described herein. The third species. A. heterophallus, collected from the east coast only, is widely-distributed throughout the Indo-Pacific region.
The cane rat, Thryonomys swinderianus, is an aseasonal breeder. It has a very low fecundity rate with an average litter size of 2.9 (range 1-5), producing a maximum of two litters per annum. The low annual fecundity is the direct result of the extended gestation period of the cane rat which exceeds 150 days in duration.
The Cape clawless otter (Aonyx capensis) is one of the few species of mammals that occur in both freshwater and marine habitats, and it therefore must be able to tolerate the high rates of water flux typical of aquatic animals as well as the desiccating effects of seawater. The clawless otter has paired, discrete multirenculate kidneys (total mass = 172 g) comprised of both unipapillary and bipapillary renculi weighing an average of 2.6 and 3.2 g, respectively. The average thickness of the cortex is 2.3 mm, and thicknesses of the outer and inner medulla are 2.4 and 6.4 mm, respectively. These measurements and the overall structure of the kidney of the Cape clawless otter are intermediate between those of freshwater and marine mammals.
In-situ observations and photographs of an unusual and spectacular red and white striped, mobile anemone, which appears to feed on gorgonians on sublittoral habitats on the south and east coasts of South Africa, prompted a closer examination of two preserved specimens. The specimens are identical with Condylactis natalensis Carlgren, 1938, which was described from a single preserved specimen and has not since been reported. The redescription of the species indicates that a new genus, Korsaranthus, is required to accommodate it within the family Actiniidae. Most significant characteristics of K. natalensis are the lack of p-mastigophores in its cnidome and the folded, distal-most part of its actinopharynx, features that compare with members of order Ptychodactiaria, which are predators of octocorals, too.
The habitats and patterns of vertical migration of the shell banding morphs of the snail Sitala jenynsi (Pfeiffer) were studied in Dar es Salaam and Wazo regions of central coastal Tanzania. Both dimorphic and trimorphic populations were arboreal throughout the year. The snails occurred randomly within mid-heights 180 to 360 cm, without apparent morph differences in micro-distribution. The pattern of circadial vertical distribution consisted of upward migrations during mornings and downward shifts during late evenings. These oscillations regressed negatively on relative humidity (RH), a unit advance in RH representing an eight-fold descent of snails on daytime height. Variations in RH accounted for much of the total variance in the mean Vertical distance. During high RH, however, temperature and mating behaviour probably exerted major influences on snail micro-distribution. The effects of arboreality on snail survival and initiation of differentiating subpopulations are proposed.
The woodland dormouse, Graphiurus murinus, in common with many other small rodents, enters torpor under conditions of food deprivation and low temperatures. Its thermoregulatory capabilities under more favourable conditions, however, have not been investigated. We measured metabolism and thermoregulation in woodland dormice acclimated to long-day length, moderate temperature and abundant food over a temperature range (T-a) of approximately 5-37 degrees C. The thermal neutral zone for this species lay between 29 and 35 degrees C. Estimated resting metabolic rate (RMR) within this range averaged 21.10 +/- 3.28 J g(-1) h(-1). Below 29 degrees C energy expenditure increased with a decrease in T-a, with a maximum value of 90.76 J g(-1) h(-1) measured at 6 degrees C. Both evaporative water loss (EWL) and thermal conductance (C) were minimal and independent of T-a between 5 and 32 degrees C but increased above the thermal neutral zone, maximum EWL and C being 6.7 mg g(-1) h(-1) (79% of metabolic heat production) and 19.74 J g(-1) h(-1) degrees C-1, respectively, at 37.3 degrees C. Thermal conductance and RMR of G. murinus were approximately 48% and 30% below predicted for rodents of equivalent mass. respectively. This pattern is consistent with that suggested for warm-temperate arboreal rodents. Although body temperature (T-b) was labile acid was significantly related to T-a over the temperature range investigated, dormice maintained T(b)s between 34 and 38 degrees C using typical thermoregulatory responses that included increased activity at low T-a and postural adjustments and salivating at high T-a. While not as impressive as some rodent species, under favourable conditions G. murinus is a competent thermoregulator and torpor in the species is facultative.
We used allozyme and RAPD-derived data to analyse genetic divergence between Clinostomum complanatum and Neutraclinostomum intermedialis. Allozyme results showed an average heterozygosity of 4.04% in the former species and 0.7% in the latter, and with extreme divergence between the two species with fixation for alternative alleles in five out of 13 loci screened. Genetic distance and fixation index values between the two species were 0.921 and 0.920 respectively. Results from random amplified polymorphic DNA (RAPD) fingerprinting revealed additional genetic diversity within species (genetic similarities 0.742 and 0.829) and confirmed considerable divergence between the two clinostomatid species (genetic similarity 0.559). The results obtained suggest reproductive isolation between the two species and convincingly nullify earlier attempts to synonymise them.
The annual cycle and reproductive ecology of a large population of Commerson's leaf-nosed bats, Hipposideros commersoni, was studied in central Zimbabwe. The influence of the extremely large body size of this microchiropteran, interrelating with a seasonal, tropical environment, was the central theme of this study. Adaptive responses to seasonal environmental changes differed between reproducing adults of the sexes. Reproductive females dispersed twice during the annual cycle, while in contrast adult males reduced activity during the cool, dry season. A polygynous mating system was characterised by breeding males defending demarcated territories within the daylight roost. Synchronized parturitions within maternity roosts (in late October) created a hot, humid microclimate which facilitated rapid post-natal development of neonates. The large body size of H. commersoni is suggested to have evolved in response to different selective agents, including: availability of large, hard shelled arthropods as prey; energetic constraints; and availability of fat reserves to 'ride out' inclement periods when food is limiting. Sexual selection may be the ultimate cause of a large body size. The conservation of H. commersoni is discussed given the history and pressures for guano exploitation of their breeding caves and the keystone role of these large bats in transferring nutrients and energy into the cavernicolous ecosystems where they roost and breed.
The striped-mouse, Rhabdomys pumilio, is widely distributed throughout southern Africa. It prefers grasslands but is also found in vlei areas and dry river beds and its attraction to cultivated land has resulted in extensive damage to plants. An allozyme study of R. pumilio populations in different regions of southern Africa was undertaken to evaluate the genetic structure within and between 23 populations and to draw conclusions about the taxonomic status of populations within this species. Fifteen of the 26 loci examined were polymorphic. The mean heterozygosity (0.073) was high for a mammal, although relatively low heterozygosities (0.036–0.054) were recorded for three localities from the peninsular region of the Western Cape. The high mean value for local genetic differentiation (Fst) of 0.459 and the low mean value for the effective number of migrants (Nm) of 0.179 indicated low levels of gene flow between the different localities of R. pumilio. The negative, near zero Fis value of -0.01 indicated a ...
Camponotus arminius is a large black carpenter ant that occurs in tropical and sub-tropical Africa and has extensive foraging trails both in trees and on the ground. Analysis of excised mandibular glands has confirmed the presence of pentane-2,4-dione, n-hexanal, 4-methyl-3-heptanone, and mellein. Pentane-2,4-dione has not been reported from insects. The postpharyngeal gland contains n-heneicosane, n-tricosene, n-tricosane, n-pentacosene, n-pentacosane, and a significant amount of 11-methyl-n-tricosane and 11-methyl-n-pentacosane. Dufours glands contain mainly n-undecane, n-tridecane, and two terpenoid compounds that are unknown in the genus Camponotus. These latter two compounds are geranyllinalool and probably geranylfarnesol.
During the 1980s and 1990s, Britain experienced an unprecedented increase in scientific and public interest in bat conservation, culminating in 90 'bat groups' by 1992. In South Africa. bats are poorly protected or unprotected, and most of the country's 54 species are poorly known. With the formation of bat interest groups in Kwa-Zulu-Natal and Gauteng in 1994 and 1995, the British 'bat group' conservation model was applied in a South African context. The primary aim of South African bat groups has been to promote bats, bat research and bat conservation through public participation and education, and the training of amateur 'bat workers' by scientists. I evaluate the success of this approach, based on activities of the Durban Bat Interest Group (DBIG) over four years (1994-1997 inclusive), and on estimates of media impact available for 1994-1996 inclusive. The number of public activities increased by between 14% and 44% per year. Some 12 million South Africans have been exposed to a positive message about bats. A database containing 316 bat roost visit records from 239 individual bat roosts (mostly in buildings) has been compiled. Two species of bats were recorded for the first time in South Africa. Conservation efforts have focussed on a roof-dwelling species restricted to the Durban area, the large-eared free-tailed bat (Otomops martiensseni); this species and one other, the short-eared trident bat, Cloeotis percivali, have recently been protected in terms of provincial legislation.
Features of laxonomic importance of Kroyeria dispar Wilson, 1935 are described from females collected from the gills of tiger shares (Gsleocerdo cuvier) captured in the southern Indian Ocean This is a first record of K dispar from South Africa and additional morphological information is given Observations were made wtth the aid of scanning electron microscopy (SEM).
Studies of morphologically dissimilar insectivorous bats have lead to the conclusion that morphology is the prime correlate of habitat use, and consequently of diet. This has lead to the prediction that morphologically similar bats should have similar diets. We examined the diet and morphology of two morphologically similar species, the slit-faced bat, Nycteris thebaica, and Sundevall's leaf-nosed bat, Hipposideros caffer, in the context of this prediction. Although both species foraged in the same habitat, they had distinctly different diets. The diet of N. thebaica consisted mainly of non-volant prey, primarily orthopterans and arachnids, and the diet of H. caffer, mainly of moths. Differences in wing design between the two taxa were small. The only significant difference was in aspect ratio. There were no differences in wing loading and wingtip shape ratio between the two species. The flying abilities reported for these two species are very similar, suggesting that these small differences in wing design do not translate into differences in flying ability, and cannot explain the dietary differences between these two species. On the other hand, there are marked differences in their prey detection systems which correspond to differences in their diets. H. caffer uses echolocation to detect the flapping wings of insect prey, whereas N. thebaica depends on prey-generated sounds (fiuttering or scuffling) to locate its targets.
We studied roost microclimates, thermal preferences and temperature-related variation in body temperatures and flight abilities of M. condylurus from three roosts in man-made structures in South Africa. Roosts were characterized by marked spatio-temporal variability in ambient temperature and relative humidity on a daily and seasonal basis. Microclimates were thermally challenging, being very hot (>40 degrees C) for several hours daily in summer and autumn, and cold (<10 degrees C) for much of the night in winter. Thermal preference tests revealed that the bats actively selected temperature zones (35 degrees-42 degrees C) in which basal metabolic rate could be maintained, and above the minimum necessary for sustained flight. This presumably allowed them to minimize energy costs of thermoregulation without compromising reproductive activity or their ability to avoid predators. Bats displayed pronounced heat tolerance and hyperthermia in response to prolonged experimental exposure to high temperatures (40 degrees C). They also exhibited cold-sensitivity, characterized by hypothermia and entry into torpor, when exposed to ambient temperatures below the thermal neutral zone. This response to low ambient temperatures would conserve energy in cold periods when the high energetic costs of foraging may not be met owing to reduced insect availability. We hypothesize that this broad roosting tolerance has energetic, ecological and evolutionary benefits that outweigh attendant disadvantages, which are largely compensated for by an unusual physiology.
Sitala jenynsi snails from the University and Wazo populations of Dar es Salaam, Tanzania, were released on grass, and on forest terrain. in both regions during the dry (February, March) and the rainy seasons (April). Snail dispersion was assessed as weekly quadratic means and as the overall Diffusion Coefficient 0.423 m(2)/week. The coefficient was enhanced by grassy habitats, continuous Vegetation cover, absence of edible plants and rainy weather; conversely, dispersion was retarded by shrubs, vegetation discontinuities, presence of edible plants and dry weather. There were differences in the rate of dispersion between populations, snails from the University Campus being faster. In each release a broadly unidirectional dispersion was recorded. The populations in question, seasons and the direction of origin of the snails seemed immaterial to directionality of dispersion. The dispersion rates of Sitala jenynsi exceeded those of the helicids Cepaea nemoralis and Theba pisana and of the partulid Partula taeniata. While observed dispersion rates of S. jenynsi may warrant the mixing of individuals in a population, they seem insufficient to facilitate appreciable migration of snails between neighboring populations.
Carbohydrate metabolism variables of Oreochromis mossambicus were investigated after acute and chronic sublethal manganese exposure. The sublethal concentrations were determined from the LC50 value of manganese. After the exposures, the fish were carefully netted and blood was drawn from the caudal aorta. The differences in the values of carbohydrate metabolism variables of exposed fish were measured against control values and statistically analysed to prove statistically significant differences in variable values, caused by the metal pollutant (P < 0.05). The results obtained showed changes in the carbohydrate metabolism variables (glucose, lactate, glucose-6-phosphate dehydrogenase and pyruvate kinase concentrations). These alterations are produced as a result of increased levels of cortisol and catecholamines, as well as hypoxic conditions. The latter induce hyperglycemia and increased lactate levels. Hypoxia may be a result of the damaging effect of manganese on the gills after exposure. The enzymes involved in the carbohydrate metabolism are sensitive to metal exposure and therefore enzyme concentrations fluctuated after the exposure to manganese. Enzyme Function plays an important role in the catalysing of chemical reactions in an organism and the disturbance thereof could lead to death. Fish enzyme levels are therefore important biomarkers in the event of metal pollution in a water source.
Echolocation data and sonograms are reported for twenty southern African bat species from 13 localities, recorded with the Pettersson D980 time-expansion bat detector. Data for eight species have not previously been reported. For seven species, two or more individuals were analysed in a range of situations, including handheld, tethered and free-flying tin a room and in different natural habitats). Sonograms, and seven echolocation call parameters agreed, with a few exceptions, with published data for individual species. Although intraspecific variation in echolocation call structure was documented, species tended to have recognisable 'vocal signatures', particularly when dominant frequency and harmonic structure were considered. The latter variables are readily retrieved by time expansion detectors, but not by frequency division or heterodyne detectors. Although generally they should be interpreted with caution, recordings from room-flown (five species) and hand-held (six species) bats obtained during this study matched. reasonably closely, additional recordings and observations of naturally flying individuals of the same species, using time expansion and heterodyne bat detectors. In four species, recordings obtained from a known species flying in a room or hand-held enabled the accurate, a posteriori species identification of unknown call sequences obtained during subsequent general recordings from bat feeding areas.
The prostate glands of male Subantarctic fur seals Arctocephalus tropicalis, taken at Gough Island (40 degrees 20'S, 09 degrees 54'W) between November 1977 and October 1978, were examined. Significant changes in the mass of the prostate, the diameter of the alveoli and height of the secretory epithelium precede the breeding season and support the fact that A. tropicalis is a seasonal breeder. Peak activity of the prostate is reached during November-January. We propose that seasonal changes in the prostate gland, and in male reproductive activity in general, may be cued by changing photoperiod. Micro-anatomical features of the prostate of the male Subantarctic fur seal differ between different age groups. Peak prostate mass, alveoli diameter and secretory cell height indicate that Subantarctic fur seal males reach full adulthood at 10-11 years of age.
