In a laboratory experiment that permitted both observations of the behaviour of individuals and the monitoring of small populations, the role of ‘intraguild predation’ in the elimination of the freshwater amphipod Gammarus duebeni celticus by the introduced G. pulex was examined. Over 18 weeks, deaths in single and mixed species replicates were monitored. Rates of ‘mortality’ (deaths not due to cannibalism or predation) did not differ between the species. Gammarus d. celticus, however, was more cannibalistic than G. pulex and, in both species, males were more often cannibalized than females. In mixed species replicates, the mean proportions of animals preyed upon did not differ among replicates with differing starting proportions of the two species, nor was there a difference between the sexes in numbers preyed upon. G. pulex, however, preyed more frequently on G. d. celticus than vice versa, and this became more pronounced over time. In 87% of mixed species replicates, G. pulex eliminated G. d. celticus. The results support the proposition that intraguild predation may be the primary mechanism whereby G. pulex rapidly replaces G. d. celticus in freshwater. Integrating behavioural observations with population level monitoring may thus link pattern and process in behaviour and ecology.

Fourteen species of erect, reticulate bryozoans are described and illustrated with SEM micrographs. Nine species introduced by P. H. MacGillivray and two by T. Hincks are included; their taxonomic status is stabilized by the selection of type specimens. A new species is described in each of the genera Triphyllozoon and Reteporellina. Dictyochasma gen. nov. is introduced for D. janus sp. nov.

Male and female Himalayan tahr Hemitragus jemlahicus exhibit extreme sexual size dimorphism and are spatially segregated outside the winter mating season. Segregation results in a greater change in both habitat selection and diet of males relative to females. Since the structure of the ruminant digestive tract is closely related to feeding habit, the rumen morphology of male and female tahr should reflect these apparently important seasonal changes. We therefore hypothesized that the rumen morphology of male tahr would undergo greater change between winter (when the sexes are aggregated) and summer (when the sexes are segregated) compared to females. Samples of rumen wall mucosa were cut from the dorsal rumen wall, atrium ruminis, caudo-ventral blindsac, and the ventral rumen wall of tahr collected during winter (eight male, 10 female) and summer (11 male, 10 female) from the Two Thumb Range, South Island, New Zealand. Although we recorded a significant seasonal increase in the mean surface enlargement factor (SEF) from winter to summer for both sexes, the SEF of females and males were not significantly different in winter (3.88 ± 0.55, SE, and 4.95 ± 0.61, respectively) or summer (7.71 ± 0.55 and 6.86 ± 0.52). We conclude that the effects of inter-sexual differences in habitat selection and diet on rumen morphology were insignificant relative to the extreme seasonal changes in forage quality and quantity that occur in the Two Thumb Range.

Wood mice Apodemus sylvaticus and house mice Mus domesticus are two of the commonest and most intensively studied British mammals. However, relative to the vast literature on non-commensal and laboratory house mice (Berry, 1981, 1991), and woodland wood mice (Flowerdew, Gurnell & Gipps, 1985; Flowerdew, 1991) little is known of the ecology of either species in and around farm buildings. Farm buildings and their surroundings are particularly important for house mice, which are a major stored-product pest (Meehan, 1984). In Britain they live largely indoors but also make limited use of hedges and fields in the summer (Rowe & Swinney, 1977; Montgomery & Dowie, 1993). Wood mice are very abundant on agricultural land, and occasionally use buildings (Green, 1979; Montgomery & Dowie, 1993; Tew & Macdonald, 1993).

The following Applications were published on 30 June 1999 in Vol. 56, Part 2 of the Bulletin of Zoological Nomenclature. Comment or advice on any of these Applications is invited for publication in the Bulletin and should be sent to the Executive Secretary (I.C.Z.N.), c/o The Natural History Museum, Cromwell Road, London SW7 5BD, U.K. (e-mail: iczn@nhm.ac.uk).

Paracrobeles psammophilus sp. nov. (Nematoda: Cephalobidae) is described from soil of the Dehesa de El Saler (province of Valencia, Spain). This is the second record of a species of the genus Paracrobeles Heyns, 1968. The new species is characterized by rounded cheilorhabdions and the large spicules and gubernaculum of males.

The aim of this study was to describe the structure of social calls produced by Kuhl's pipistrelles Pipistrellus kuhlii. Bats foraging around street lamps in the Campania region, Southern Italy, were recorded. Calls were produced by bats during chases and, similarly to those of Pipistrellus pipistrellus, were probably used to repel conspecifics from hunting sites. Calls often had three components, lasted on average 34 ms and contained most energy at about 17 kHz. A positive correlation was found between the frequencies of maximum amplitude of echolocation and social calls. Social calls from two adjacent populations differed in their peak frequencies, and possible hypotheses for this variation are given. The structure of P. kuhlii social calls was compared with those of the 45 and 55 kHz P. pipistrellus phonic types. Kuhl's pipistrelle calls lasted longer and showed lower values of minimum and peak frequencies. These differences can help to discriminate between field recordings of P. kuhlii and P. pipistrellus where the two species occur sympatrically.

The set-aside scheme, whereby land is removed from arable production, is primarily aimed at manipulating agricultural surplus within the European Community, but has potentially great consequences for biodiversity and wildlife management (Feber et al., 1995; Macdonald et al., 1998; Sotherton 1998). Managed inappropriately, set-aside could prove environmentally damaging by reducing biodiversity and directly harming certain species, such as ground-nesting birds (Thompson, 1993). Conversely, appropriately managed set-aside could foster desirable ecological communities, with enhanced populations and biodiversity.

Among mammals, non-offspring nursing is the most extreme form of communal parenting. This is because lactation is the most energetically costly part of parental investment (Clutton-Brock, 1991; Packer, Lewis & Pusey, 1992). Non-offspring nursing is most common in species characterized by large litters and small kin groups (Packer et al., 1992; e.g. lions Panthera leo: Pusey & Packer, 1994). Although non-offspring nursing has also been reported in monotocous species (e.g. water buffalo Bubalus bubalus, Murphey et al., 1995; African elephant Loxodonta africana: Dublin, 1983; Lee, 1987; Indian elephant Elaphus maximus: MacKay, 1973; Rapaport & Haight, 1987; fallow deer Cervus dama: San José & Braza, 1993) it is almost always associated with reproductive errors (Riedman, 1982) such as milk theft or exclusive adoption (Packer et al., 1992). However, simultaneous non-offspring nursing in monotocous species has been reported in some bat species (e.g. McCracken, 1984; Eales, Bullock & Slater, 1988), African elephants (Lee, 1987), and captive Indian elephants (Rapaport & Haight, 1987). Recent research, however, suggests that nutritive non-offspring nursing in African elephants is rarer than previously thought as most reported instances were probably non-lactating juveniles allowing infants to suckle (Lee & Moss, 1986; Lee, 1987, 1989).

The morphology of the spermathecae (seminal receptacles) was studied in the grapsid crab Chasmagnathus granulata, both from the macroscopic and the microscopic points of view. Female adult crabs were collected throughout the year. Once in the laboratory, the right spermatheca was fixed in Bouin solution; histological sections were stained with haematoxilin–eosin. The observations indicated that the spermathecae belonged to the ‘ventral type’ described by Diesel (1991), related to the ‘hard female’ mating system of C. granulata described previously. They presented two distinct zones: the inner one (white-coloured), where the double layer oviduct opened ventrally; and the outer one, of translucent, ‘jelly-like’ appearance, where the communication with the genital duct could be observed. The spermatozoa were only observed in the ‘jelly-like’ zone, but not as discrete packets, suggesting that spermatozoa from different matings could mix in the spermathecae of C. granulata. The spermathecae also showed seasonal variation, with the lowest degree of development observed during autumn. Post-moulted females always showed collapsed spermathecae.