New deep-sea Tardigrada (Arthrotardigrada,Halechiniscidae) from a manganese nodule area of the eastern South Pacific*

Three new Tardigrada species are described from a manganese nodule area of thc abyssal castern South Pacific. Moebjergarctus mangunis gen. et sp.n. is characterized by its segmcntcd ccphalic cirri, club-shaped and forward bent primary clavae, spherical secondary clavae, spines on legs I, 11, 111, small clavoid papillae on legs IV, long cirri E, and corkscrew-shaped digits with simple claws. Angursa capsula sp.n. is distinguished by the presence of secondary and tertiary clavac, occurring as elevated cuticular areas, club-shaped primary clavae, short lateral cirri, short median cirrus, spines on legs I and hcmisphcrical, capsulc-shaped papillae on legs IV. Angursa lingua sp.n. is characterized by the presence of secondary and tertiary clavae, occurring as elevated cuticular areas, balloon-shaped primary clavae, long lateral cirri, long median cirrus, spines on legs I, clavoid papillae on legs IV and weakly broadened distal parts of cirri E, resulting in tongue-shaped swellings. A simple key to the species of Angursa is presented.     

Changing Sink Demand Affects the Area but not the Specific Activity of Assimilate Sources in Cantaloupe (Cucumis meloL.)

To better understand source-sink interactions, this work focusedon the influence of fruit number on leaf area and photosyntheticactivity in cantaloupe. To this end, flowers were removed over2 years on two Charentais cultivars to obtain single-fruit plantsand plants with an unrestricted fruit load (which set two tofive fruits and constituted control plants). At the whole plantscale, net photosynthesis was reduced by about 30% under highfruit load. At the leaf scale, a submodel of stomatal conductancewas fitted to the data and was included in a rectangular hyperbolamodel of leaf photosynthesis. Maximum leaf net photosynthesisaveraged 14.83 µmol CO₂m^-2s^-1at 1000 µmol quantam^-2s^-1. Light use efficiency was not affected by fruit loadand equalled 0.040 mol CO₂mol^-1quanta. Leaf area of plants withunrestricted fruit load decreased after 24 days from pollination,while the leaf area of single-fruit plants was still increasing.The decrease was due to production of fewer new leaves per day,whereas the number of senescent leaves and the size of individualleaves were not affected by the treatment. Under high fruitload, cultivar Galoubet developed a larger projected leaf areathan cultivar Talma. Thus it is concluded that: (1) large cantaloupefruits may divert a large amount of assimilates away from, andgrow at the expense of, the canopy; and (2) photosynthesis ofthe canopy was lowered because leaf area was reduced whereasphotosynthetic rate of leaves was not altered.Copyright 1998Annals of Botany Company. Cucumis meloL., fruit load, source-sink interactions, leaf photosynthesis, canopy photosynthesis, leaf area, SLA, source strength.     

The effects of fire on the frillneck lizard (Chlamydosaurus kingii) in northern Australia

Abstract A population of frillneck lizards, Chlamydosaurus kingii, was monitored by radio telemetry and mark-recapture techniques between April 1991 and April 1994, as part of a landscape-scale fire experiment, in Kakadu National Park, Northern Territory. The study aimed to investigate both the short- and longer-term effects of fire on a lizard species in a tropical savanna where fires are frequent and often annual. Frillneck lizards are able to survive fires that occur in the first few months of the dry season by remaining perched in trees. A high level of mortality (29%) occurred during late dry-season fires, along with changes in their behavioural response to fire: sheltering in either larger trees or hollow termite mounds. Food is more accessible after fires due to the removal of ground vegetation. This is reflected in greater volume and diversity of prey in stomach contents after fires. This increase is more pronounced after late dry-season fires, possibly due to increased accessibility of prey caused by more complete vegetation removal. Frillneck lizards show an overall preference for trees with a dense canopy cover located in an area with a low density of grass. Fire has an effect on this relationship. Frillneck lizards in habitat unburnt for a number of years tend to perch in trees with a smaller canopy, whereas lizards in annually burnt habitat perch in trees with a dense canopy. Volume and composition of lizard stomach contents was broadly similar among fire treatments over a 2 year period, although termites were more predominant in stomach contents of lizards in unburnt habitat. Wet-season body condition is lower in lizards from unburnt habitat, although the reason for this is unclear. These results demonstrate the importance of different fire intensities and regimes on the ecology of a lizard species in a tropical savanna.     

The effect of visual input on calling song attractiveness for female Acheta domesticus

ABSTRACT. Of twelve mature phonotactically-responsive female Acheta domesticus L., ten responded phonotactically to a wider range (30 or SO to 100 ms) of model calling song (CS) syllable periods (SP) on the Kramer treadmill in the dark than in a lighted visually structured arena (50–70 ms). When given a choice between the visually attractive target and the invisible loudspeaker, seven of the ten females that tracked a visually attractive target (black square) when presented alone in the light reduced the range of SPs they tracked phonotactically to 50–70 ms. Three of the ten females that were not strongly attracted to the visual target when presented alone, continued to respond to model calling songs with a wide range of SPs (30–100 ms) when given a choice between visual and acoustical targets under the same conditions. Two of the twelve females responded only to model calling songs with a 50–70 ms SP on the Kramer treadmill in the dark. These females did not change their choice for model calling song SPs when presented with the visually attractive target.     

Changes in Enzymes of Sucrose Metabolism and the Activation of Certain Chloroplast Enzymes During Wheat Leaf Senescence

Relatively little change was observed in the partitioning ofphotosynthetically fixed carbon between sucrose and starch duringsenescence of vegetative leaves of wheat (Triticum aestivumL. cv. Roy). The maximum activities of sucrose phosphate synthaseand cytoplasmic fructose-1, 6-bisphosphatase in leaf extractsapproximated photosynthetic sucrose formation in leaf segmentsand the three parameters declined together with age. Changesin activities of sucrose synthase and uridine-5'-diphosphatase,and in leaf phosphate content did not parallel changes in sucroseformation with age. Chloroplast fructose-1, 6-bisphosphatase activity, activatedin vivo with light and in vitro with dithiothreitol, declinedcontinually throughout senescence of the second vegetative leaf.The ability of light to activate chloroplast fructose-1, 6-bisphosphatasedid not, however, appear to change with age. Ribulose-l, 5-bisphosphatecarboxylase activity also declined continually with age, butin vivo-activated ribulose-l, 5-bisphosphate carboxylase wasa minimum of three fold greater than needed to account for photosyntheticactivity. The percentage of ribulose-l, 5-bisphosphate carboxylaseactivated in vivo was essentially constant during senescence.In general, activities of soluble chloroplast enzymes declinedcontinually from the point of full leaf expansion throughoutsenescence, whereas the activities of cytoplasmic enzymes thatwere studied remained relatively constant until the latter stagesof senescence. Key words: Wheat leaf senescence, Sucrose metabolism enzymes, Chloroplast enzymes     

Auditory nerve and interneurone responses to natural sounds in several species of cicadas

ABSTRACT. The calling and courtship songs of 17-year cicadas and of Say's cicadas differ both in the sound frequency spectrum and in temporal pattern. Multiunit recordings with hook electrodes from the whole auditory nerve show that the hearing organs are especially sensitive to transient stimuli occurring in natural sounds. Artificially produced clicks elicit bursts of spikes synchronized among various primary sensory fibres. These fibres respond to natural calling and courtship songs with a specificity dependent on carrier frequency, rhythm and transient content of the sound, following sound pulses (i.e. tymbal actions) up to repetition rates of 200 Hz. An ascending, plurisegmental interneurone was characterized by intracellular recording and simultaneously stained with cobalt. Its main arborization spatially overlaps the anterior part of the sensory auditory neuropile, and the axon was traced as far as the prothoracic ganglion. Direct input from primary auditory fibres was suggested by latency measurements. Intracellular recordings from such neurons in different species show distinct auditory input, with phasic-tonic spike responses to tones. In general, the interneurone response is more species-specific to calling than to courtship songs, and the preferential response to the conspecific calling song is based primarily upon sound frequency content.     

What’s in a frog stomach? Solving a 150‐year‐old mystery (Diptera: Calliphoridae)

Abstract.  The nominal taxon Acanthosoma chrysalis Mayer, 1844 is revised, and a lectotype is designated. The species, which was described from Germany from a number of alleged parasites encysted in the peritoneal wall of the stomach of edible frogs, is shown to be based on first instar larvae of blow flies (Calliphoridae). Argued from the shape and configuration of mouthhooks and abdominal cuticular spines, Acanthosoma Mayer, 1844 is shown to be a junior synonym of Onesia Robineau-Desvoidy, 1830 , syn.n. , and A. chrysalis is shown to be a junior synonym of O. floralis Robineau-Desvoidy, 1830 , syn.n. This species is an obligate parasitoid of earthworms, and it is hypothesized that first instar larvae enter the frogs through infected earthworms.