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1.
We determined the distribution and estimated population number of Preston White River springfish ( Crenichthys baileyi albivallis ) in summer 1998 and winter 1999. The total population was < 5000 fish persisting in only 4 of 6 spring systems from which it had been previously captured. To improve its status, we recommend conservation measures.  相似文献   

2.
ABSTRACT

The genus Pseudopaludicola includes small-sized anurans, widely distributed throughout South America. Twenty-three out of the 25 species occur in Brazil. Although described more than a century ago, from mid-southern Mato Grosso state, central Brazil, Pseudopaludicola ameghini is poorly known. Here we describe the characteristics of reproductive site, amplexus, egg-laying behaviour, eggs and tadpoles of P. ameghini based on specimens and observations performed in the vicinities of the type locality. Pairs of P. ameghini reproduce in shallow and slow groundwater established on hydromorphic terrains, in open environments amidst the Brazilian Cerrado savanna. Reproductive activity occurred between 17:00 and 21:00 h at two sites studied from December 2013 to April 2014. Amplexus is axillary. Eggs are spherical, with a mean diameter of 5.1 mm (yolk plus jelly envelope). Oviposition occurs in shallow sites at a depth of nearly 2.0 cm. Females deposit their eggs one at a time, directly onto sediment at the bottom of waterbodies or attached to submerged vegetation. The tadpole body is oval in dorsal view and globular/depressed in lateral view; eyes are large and dorsally positioned. Nares are large, round, with a small apophysis on marginal rim, dorsally positioned, near the eyes. The spiracle is short, with posterodorsal opening. The oral disc is anteroventral, emarginated laterally, with one dorsal and two ventral gaps; the tooth row formula is 2(2)/2(1), and the upper jaw sheath is ‘arc’ shaped. Pseudopaludicola ameghini has a unique behaviour of oviposition among members of the genus. The differences in reproductive pattern and larval characteristics of P. mystacalis and P. ameghini reinforce the taxonomic validity of the latter, questioned until recently.  相似文献   

3.
Further information on the following species of the freeliving marine nematode family Ethmolaimidae is provided based on specimens made available subsequent to a major revision of the group: Ethmolaimus multipapillosus Paramonov 1926, Gomphionema euripus Platt 1982, Gomphionema sp. (= G. aff. typicum of Riemann and Rachor 1973) Comesa corcunda Gerlach, 1956 and Comesa votadinii (Warwick 1971). Neotonchoides Platt, 1982 and Comesa Gerlach, 1956 are synonymized, the latter being the valid name. Pictorial keys are provided for the identification of valid Ethmolaimus and Gomphionema species.  相似文献   

4.
The interaction between a grass-feeding mirid, Irbisia pacifica (Uhler), and plant growth of intermediate wheatgrass, Thinopyrum intermedium (Host) Barkw. & D. R. Dewey, was examined on a field site in northern Utah in 1985. With egg hatch beginning in April, the bug completed its life cycle within two months. Ovarian development was completed by 11 June, a week after all bugs had become adults. The proportion of feeding damage per leaf (35.1%) peaked on the seventh week of the twelve-week study (18 July). Green leaf area per tiller decreased initially from bug feeding and then continued to decrease because of seasonal aging. All plants senesced within three months. Grass bugs predominantly attacked the second and third youngest leaves. Analyses of age-specific leaf cohorts demonstrated that the major effect of bug feeding was the loss of green leaf area and potential foliage production over time. Bug feeding may also exacerbate other physiological stresses on the host plants.  相似文献   

5.
White River springfish collected in August and December 1966 from Hot Creek Spring, Nevada, fed primarily on amphipods, ostracods, plant fragments, and detritus. Compostition of the diet was similar in both months. However, amphipods were the most important food in August, while in December amphipods, ostacods, plant fragments, and detritus were of approximately equal importance. Comparison of diel feeding periodicity and activity patterns suggests that most of the daily activity of White River springfish is related to feeding.  相似文献   

6.
Four populations of the spotted frog, Rana pretiosa , occur in western Bonneville Basin. Only the Tule Valley populations occupy aquatic habitats associated with warm (28°C) and slightly saline (1700-2700 μmhos/cm) springs. The spotted frog in Tule Valley breeds in cold-water portions of the peripheral wetlands, which exhibit maximum temperature variations (1-25°C), maximum conductivity up to 3200 μmhos/cm, and maximum pH values up to 9.7. Adult frogs are found in habitats with temperatures of 29°C, conductivity of 4700 μmhos/cm, and pH above 9.0 in the summer. The increased summer salinity and pH in frog habitats returns to lower values by the next breeding season due to underground recharge. Breeding in Tule Valley occurs earlier than in other Bonneville locations because of the warm-water sources. Spatial and temporal distribution of the spotted frog since the regression of Lake Bonneville 15,000 years ago and threats to present habitats are discussed.  相似文献   

7.
8.
Eight study sites were examined in Strawberry Valley, Utah, to assess the response of aspen ( Populus tremuloides Michx.) to cutting activities of beaver ( Castor Canadensis Warren & Hall) and to determine patterns by which the animals utilize aspen stands. Sites utilized by beaver, along with adjacent control plots in mature, uncut aspen stands, were sampled. Age-class profiles of control plots were composed of a broad age distribution with trees ranging from 3 to 108 years old. Age-class profiles for aspen sprouts in areas previously used by beavers were composed of trees averaging seven years of age with a range of 1 to 24 years. Age distribution of sprouts in areas used by beaver show a tendency to be skewed toward younger age classes. Average density of aspen in areas used by beaver was 15,800stems per hectare compared to 2,980 stems per hectare in controls. Stump densities in use areas ranged from 900 to 5,066 stems per hectare. Densities of stumps in the 0-5-cm size class were greater in areas used by beavers than in the corresponding size class in the mature forests. A regression equation describing age versus diameter relationships was calculated using data from 312 aspen trees. Total phenolics and mineral nutrients in the twigs and bark of mature aspen trees and aspen sprouts were also examined to determine if variations could explain foraging patterns of beaver in the valley. Total phenolics were highly variable between sampling groups, and differences were not significant. Twigs from mature aspen and aspen sprouts were significantly higher in nitrogen, phosphorus, and iron. Zinc was significantly higher in the bark of mature aspen trees and twigs of aspen sprouts. Calcium concentrations were significantly higher in mature aspen bark, and magnesium was significantly higher in mature aspen twigs.  相似文献   

9.
Blackbursh ( Coleogyne ramosissima Torr.) is a dominant desert shrub in a distinct mid-elevations vegetation belt between creosote bush-bursage ( Larrea tridentata-Ambrosia dumosa ) shrubland below and big sagebrush-pinyon pine- Utah juniper ( Artemisia tridentata-Pinus monophylla-Juniperus osteosperma ) woodland above in the Mojave Desert. Seed germination patterns of blackbrush seeds collected from 2 elevations (1200 and 1550 m) in 5 mountain ranges within the blackbrush shrublands were investigated. Morphological features of blackbrush seeds, including weight, length, and width, were not significantly different ( P > 0.05) among elevations and mountain ranges in the Mojave Desert. Germination of blackbrush seeds was optimal when preceded by a prechill period of 4-6 wk. Seeds incubated at room temperature germinated poorly. Seeds collected at warm, low-elevation sites appeared to be less dormant (required less prechill time), germinated faster, and showed a higher overall germination response; watering at 2-wk intervals revealed the greatest germination. Some ecotypic variation among populations establishing at different elevations was evident with regard to dormancy duration and germination response at certain constant temperatures.  相似文献   

10.
Transmission electron microscopy was used to evaluate the ultrastructural morphology of some other symbiotic prokaryotes of Joenia annectens, an intestinal flagellate of the termite Kalotermes flavicollis. Three morphotypes are predominant and recognizable from their morphological characteristics. One morphotype is represented by spirochaetes that are mainly external and cover the flagellate, helping its movement. Rod-shaped bacteria, which represent the second morphotype, are also attached to the surface among the spirochaetes. Rod-shaped bacteria and some spirochaetes may enter the cell surface of Joenia annectens as a consequence of phagocytosis, remaining enclosed in an envelope of plasma membrane. A nutritive role of rod-shaped bacteria in this symbiotic association is suggested. A third, different morphotype of prokaryotes is represented by roundish microorganisms which, gathered together with other cytoplasmic organules, form a large collar, encircling the axostyle; their function is still unknown.  相似文献   

11.
12.
13.
Summary

The segmental chaetotaxy of the legs of some larval ixodid ticks has been studied, employing the system of nomenclature currently used for the mesostigmatic mites. Preliminary results indicate that in common with the larval Mesostigmata, the family Ixodidae has a relatively constant larval leg chaetotaxy which allows the subfamilies and tribes to be distinguished on the basis of the chaetotaxy of the tibiae.  相似文献   

14.
The hypothesis that temperature influences the toxicity of copper to thermophilic Cyanophyceae was tested in a laboratory study with Synechococcus lividus. This thermophile was tested at copper concentrations from 0 to 200 &micro;g/1, and temperatures from 40.0 to 50.0 C. It was found that an interaction between increased copper and temperature significantly decreased the rate of carbon assimilation, chlorophyll content, and photosynthetic efficiency.  相似文献   

15.
16.
Observation on prezoeas of three Pagurus species inhabiting the coasts of Hokkaido, P. lanuginosus de Haan, P. middendorffii Brandt, and P. brachiomastus (Thallwitz), were carried out using light and scanning electron microscopy. Hatching was produced at laboratory conditions of 17·5–18·2 °C and 32·5–33·2 ppt salinity, and after a short duration of 5–10 min, most of prezoeas moulted to the first zoeal stage. Prezoeal appendages are described and figured; previous observations on prezoeas in allied groups are summarized.  相似文献   

17.
A new species of the genus Beebeomyia Curran found in central Veracruz (Mexico) is described, including characters of the male and female terminalia, and a key to the identification of the known species is provided. This new species was found feeding within inflorescences of Dieffenbachia oerstedii Schott (Araceae). Larvae were found throughout the inflorescence, with a proportion nearly three times higher in the female (bottom) than the male (top) section. The life cycle from larval stage to adult emergence takes place in an average time of 42 days, while pupation occurs within the inflorescence. Observations of the oviposition behaviour suggest that after oviposition, the female marks the inflorescence with a deterrent pheromone to prevent further ovipositions by other conspecific females.

http://zoobank.org/lsid:zoobank.org:pub:DC19F7E5-3AAF-4E5C-A35C-F4872C89D3B4  相似文献   

18.
A study was made of the soil mites from under different vegetative types near a coal - burning power plant in the Yampa Valley near Hayden, Colorado. The following new species of oribatids were found: Zygoribatula apletosa n.sp., Multoribates haydeni n.sp., Paraphauloppia cordylinosa n.sp., Passalozetes moniles n.sp. &nbsp;  相似文献   

19.
Sixty-two species of primarily ground-nesting Sphercidae were studied in order to assess their counter-cleptoparasitic behaviour against nine species of associated cleptoparastic miltogrammine flies. Fly larviposition was altered or thwarted by species-specific nesting patterns and distinctive behavioural components of the wasps. Pre-larvipositional, counter-cleptoparasitic behaviours included freeze-stops, face-offs, diversionary and chasing flights, butting, stinging and male nestguarding. Post-larvipositional counter-cleptoparasitic behaviours involved the actual removal of maggots from the prey by the wasp, cell and burrow cleaning, prey and cell abandonment and maggot destruction by the larvae of progressive provisioning species.  相似文献   

20.
Three species of Elmidae occur in Death Valley National Monument: Stenelmis calida is in three springs in the Ash Meadows area; Microcylloepus formicvideus is only in Travertine Springs; and Microcylloepus similis is in several springs throughout Death Valley and Ash Meadows. Only permanent springs support elmids. Considerable morphological variation occurs in the disjunct populations of M. similis . The evolution of elmids in Death Valley National Monument is equivalent to that of the local pupfish ( Cyprinodon spp.).  相似文献   

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