AN OCTOPUS WITH ONLY SEVEN ARMS: ANATOMICAL DETAILS

A male specimen of Octopus is described which has only sevenarms: the fourth right arm is congenitally absent. Dissectionreveals that, as in normal octopuses, eight brachial nervesarise from the brain. However, right brachial nerves 2, 3 and4 are connected by unusually short lengths of the interbrachialcommissure, distal to which right brachial nerves 3 and 4 runtogether, with corresponding arteries, into the third rightarm. Hectocotylization of the latter confirms that it is thefourth right arm which is missing. Other abnormalities of thespecimen include an obviously asymmetrical funnel organ andthree pairs of conjoined suckers. An old specimen of Octopus described as having only seven armswas re-examined for comparison. This animal, too, appeared tohave no fourth right arm, but on closer inspection the extremelyshort stump of this arm was discovered. ^*Present address: National Institute for Basic Biology, Nishigonaka38, Myodaiji-cho, Okazaki 444, Japan (Received 10 August 1988; accepted 1 November 1988)     

Behaviour of a young smooth snake, Coronella austriaca Laurenti

In August 1976 two broods of the endangered smooth snake ( Coronella austriaca ) were rescued from a fire at a National Nature Reserve. This material provided a unique opportunity in which to observe the behaviour of the young animals before they were returned to nearby heathland. It soon became apparent that the young snakes have narrow food preferences because only the young of lizards were taken. However, evidence is presented which suggests that later they do take the young of small mammals as do adult smooth snakes. Observations on other aspects of their behaviour, such as burrowing, have helped to elucidate the complex day to day behaviour of the adults.     

Evidence for mate‐encounter Allee effect in an invasive longhorn beetle (Coleoptera: Cerambycidae)

1. Limited empirical support is available for mate‐encounter Allee effects in invasive insects due to the logistical challenges of studying demographic trends in low‐density populations. 2. Traps baited with pheromone and spruce volatiles were used to monitor the abundance of female Tetropium fuscum F. (Coleoptera: Cerambycidae) at multiple sites in Nova Scotia in 2011 and 2012. Each female was dissected to determine the presence or absence of sperm in its spermatheca (mated or virgin female, respectively). 3. Both male and total T. fuscum abundance declined with increasing distance to the focal point of T. fuscum's invasion. Female mating probability declined with male abundance and with distance from the invasion focus, and mating probabilities were very low at the most peripheral sites. Difficulty in encountering mates may thus contribute to limiting the spread of T. fuscum. 4. The approach outlined here could be integrated into existing surveys of wood borers using traps baited with semiochemicals to improve our understanding of the role of the mate‐encounter Allee effect in invasion dynamics.     

Allochthonous coarse particulate organic material in forest and pasture reaches of two south-eastern Australian streams

1. Terrestrial plant litter entering two forest and two pasture sites on upland streams in south-eastern Australia was measured over a 2-year period using traps suspended above the streams. Laterally transported terrestrial plant litter was also determined in one stream, but found to be only 10% of the total. 2. Litter accession to traps suspended above the stream was significantly lower at both forested sites than was litter fall in the adjacent riparian vegetation. 3. Litter input was high (600–700g DW m^?2yr^?1) and seasonal, with 30–50% of the annual total entering the stream during December—February (summer). However, seasonality was not as great as that recorded in Northern Hemisphere deciduous forest streams. 4. Leaves comprised the largest litter component, but represented a relatively smaller proportion of the litter than is usually the case in Northern Hemisphere deciduous forest streams; in contrast bark was a relatively large proportion of the litter. 5. At the sites flowing through pasture, litter accession was about two orders of magnitude lower than at the forested sites.     

Coccidia (Eimeria tachyglossi n. sp., E. echidnae n. sp., and Octosporella hystrix n. sp.) in the Echidna, Tachyglossus aculeatus (Monotremata: Tachyglossidae)

Oocysts of Octosporella hystrix n. sp., Eimeria tachyglossi n. sp., and E. echidnae n. sp. are described from the feces of the echidna Tachyglossus aculeatus (Monotremata: Tachyglossidae) from Australia. Eimeria tachyglossi has subspherical oocysts, 26.4 × 23.7 μm in size, with a single oocyst wall; no micropyle; four ellipsoidal sporocysts 13.2 × 9.7, slightly pointed at one end, each containing two sporozoites. Eimeria echidnae has subspherical oocysts, 19.4 × 17.8 in size, with a single oocyst wall; no micropyle; four ellipsoidal sporocysts 9.8 × 7.8, blunt at both ends, each containing two sporozoites. Octosporella hystrix has ovoid or subspherical oocysts 32.9 × 29.7 in size with a thick outer and thin inner oocyst wall; no micropyle; eight sporocysts spherical or slightly subspherical 11.3 × 11.2 each containing two sporozoites lying in embrace, with an extensive granular sporocyst residuum about the equator of the sporocyst. Endogenous stages considered to be of E. tachyglossi at least, were recognized in the lamina propria and epithelium on villi in the small intestine of three echidnas.     

Comparison of insects and vertebrates as removers of seed and fruit in a Western Australian forest

Removal from the forest floor of seed or fruit of the six commonest species of trees in upland areas of the northern jarrah forest of Western Australia was studied experimentally. The smallest seeds (Eucalyptus marginata, Allocasuarina fraseriana) were taken by insects (presumably ants). Heavier seeds or fruits (E. calophylla, Banksia grandis, Persoonia longifolia, P. elliptica) were taken more often by vertebrates (presumably srrmll mammals). Seeds of E. calophylla and B. grandis were most preferred by vertebrates, possibly because they have the highest relative concentrations of nitrogen and phosphorus.     

Home range size and distribution in a wild population of Cape pangolins, Manis temminckii, in north‐west Zimbabwe

The aim of this study was to estimate the size of the home range used by individual Cape pangolins ( Manis temminckii ). The study was conducted in 1991–95 at Sengwa Wildlife Research Institute, Gokwe, Zimbabwe. Radio‐telemetry was used to repeatedly locate study pangolins. Home range area was estimated from the location of the burrows used by each pangolin. It was established that pangolins must be tracked for 85+ days to generate a reliable estimate of home range. The size of home ranges, determined from 1141 tracking days of data for 10 pangolins (3·0–15·8 kg body mass) that were each tracked for at least 85 days, was from 0·17 to 11·07 km². Larger (older) pangolins used more burrows and had larger home ranges than smaller (younger) pangolins. The data indicate that large adult males had larger home ranges than large adult females. Within each sex, the home ranges were adjacent to each other with only slight overlap at the boundaries. There was clear overlap of home ranges between males and females.     

The Role of Small Cardioactive Peptide, SCPB, in the Regulatory Responses of Terrestrial Slugs

The feeding motor program in Limax maximus is the neural correlateof feeding and consists of a discrete pattern of cyclical efferentactivity generated by the buccal ganglia in response to stimulationof chemosensory pathways. The small cardioactive peptide, SCP_B(10^–6 to 10^–9 M), increases the responsiveness ofthe FMP and the endogenous activity of specific feeding motoneuronssuch as the fast salivary burster. Stimulation of buccal neuron,B1, which contains SCP_B-like immunoreactive substance, similarlyincreases the activity of feeding motoneurons. Furthermore,both exogenous SCP_B and stimulation of Bl increase the contractileforce of the heart. Thus it appears that the peptidergic neuronBl is a multifunctional interneuron that is involved in thecontrol of both peripheral and central targets.     

Freshwater triclads (Turbellaria, Tricladida) from the oriental region

Two new freshwater triclad species of the genus Dugesia Girard, 1850 are described from the oriental region. The first is the only species of freshwater triclad described from Ceylon and the second, a cavernicolous form, is the only one known from Malaya. A synopsis, in tabular form, of the oriental Dugesia species is also given and some aspects of their distribution are discussed. It is intended that the tabular synopsis should provide diagnostic characters for the delimitation of the new and previously described species, and act as a basis for a future revision of the oriental representatives of the genus, many of which are poorly described or poorly known. Apreliminary dichotomous key to the valid species is also provided.