Morphometric data from Fennoscandian populations of the crested newt Triturus cristatus and the smooth newt Triturus vulgaris were analysed for the presence of sexual size and shape dimorphism. The data sets included nine body-related and nine head-related measurements and were examined with univariate, bivariate and multivariate methods. Sexual dimorphism was demonstrated in both species. The separation of specimens was highly related to sex. Although the expression of sexual dimorphism differed between the two species, some patterns were shared. These are discussed in terms of evolution of intersexual dimorphism according to models of ecology, fecundity and sexual selection. In multivariate analyses, sexual dimorphism was restricted to body-related variables such as standard length and distance of extremities (with high values for females), contrasting against cloaca and limb-related characters (with high values for males). In both species, the ‘distance of extremities’ measure (i.e. trunk length) was one of the strongest sexually dimorphic traits. No evidence of sexual dimorphism in head morphology was found. The results are interpreted as primarily concordant with theories on fecundity selection. For example, it has been suggested that females with larger trunk volumes increase their reproductive capacity. The fact that males had longer extremities, in relation to other characters measured, could be attributed to sexual selection. Long limbs in male newts may be beneficial for courtship performance. Since head-related characters did not show any patterns of sexual dimorphism, no evidence was found to suggest that male and female crested and smooth newts have adapted to different feeding strategies.

Populations of Potamonautes perlatus were sampled at various points along the Olifants Rivers (220 km), in the Western Cape to examine the degree of genetic variation. Allozyme electrophoresis revealed a near fixed allelic difference at one locus and extensive differentiation at another locus between populations from the upper and lower reaches of the Olifants River system. Limited hybridization in the region of population sympatry was observed. The narrow hybrid zone and the low occurrence of hybrids suggest selection against hybrids. These results provide evidence for two genetically distinct freshwater crab populations. We concluded that the genetic divergence between the two population groups represents a species boundary between the two populations.

The foraging behaviour of wild and captive colonies of the common mole-rat Cryptomys hottentotus hottentotus was investigated. Field studies were undertaken at Steinkopf, an arid site in the Northern Cape, South Africa. The resource biomass and the total available energy here were amongst the highest recorded for any bathyergids, but geophytes were sparse and widely distributed. The low probability of locating these widely dispersed resources should promote co-operative foraging in these mole-rats. All common geophyte species were consumed, probably because high burrowing costs favour dietary generalism. The mole-rat biomass per metre of burrow system (0.5–1.5 g.m-1) remains the lowest of any subterranean mammal. Burrow depths and diameters were positively correlated to the average mass of the mole-rats in each colony, apparently minimizing energetic costs and maximizing foraging success. Bulbs were stored in central food caches, and both field and laboratory data indicated size-based selectivity in their storage and consumption. As predicted by central place foraging theory, large bulbs were preferentially stored, and small bulbs preferentially consumed. However, factors other than energetic considerations may also influence these storage decisions. Total consumption time of bulbs was negatively correlated to animal size, and furthermore smaller bulbs were consumed more rapidly than larger ones. In addition to geophyte-storing, C. h. hottentotus also exhibited an alternative foraging strategy, termed ‘geophyte farming’, in which large bulbs were left and eaten in situ, and served as a renewable resource. Together with these foraging specializations, the evolution of sociality in mole-rats is a key factor which enables them to live in some of the most formidable habitats in Africa.

Restriction fragment length polymorphism (RFLP) was studied for six populations of the polytypic snail Neotricula aperta using seven different restriction enzymes. Samples of all three strains of N. aperta from north-eastern Thailand were examined, as well as topotypes from southern Laos and material from Kampuchea and central Laos. Genetic distances were estimated as Nei & Miller's (1990) distance ×100 (D). The samples were taken from the Mekong, Mul and Xé-Bang-Fai (XBF) rivers of the lower Mekong basin. The γ-strain of Kampuchea and southern Laos has been shown to act as intermediate host for Schistosoma mekongi. The least amount of genetic divergence was found where the α-strain was compared with other taxa (D, 2.1–3.7), and the largest values for comparisons involving samples of the XBF strain (D, 2.1–6.4). Large distances were apparent between the b-strain and all the γ-strain populations (D, 4.0–5.5). The β- and XBF-strain may represent a pair of sibling species with respect to N. aperta. The γ-strain population of north-eastern Thailand comprised two cryptic taxa which were relatively well diverged (D = 1.6). Only one of these cryptic taxa showed close affinity with other γ-strain taxa; this finding may be important in the control of Mekong schistosomiasis.

The morphology of the sperm storage organ (spermatheca) may influence the outcome of sperm competition in a variety of invertebrate species. Simultaneously hermaphroditic pulmonates show considerable inter- and intraspecific variation in the structure of the spermatheca. The morphological variation in the spermatheca (number of spermathecal tubules and tubule length) and the amount of sperm stored in the tubules in 115 individuals of the simultaneously hermaphroditic land snail Arianta arbustorum (L.) from six natural populations in the Eastern Alps (Gesäuse, Austria) was examined. The populations differed in snail density, therefore in the number of potential mating partners (range: 0.9–39.8 individuals/m2) and thus in the sperm competition risk. The number of spermathecal tubules ranged from two to nine. However, the six populations did not differ in either the mean number of spermathecal tubules, the length of the main tubule (range 0.9–3.4 mm), or in the cumulative length of the tubules (range 1.5–7.8 mm). The number of tubules and tubule length were not correlated with either shell height and shell breadth or with population density. The amount of sperm stored in the spermathecal tubules was estimated. Individuals from different populations did not differ in the amount of sperm stored, and the amount of sperm stored was not correlated with population density. Results indicate that the risk of sperm competition does not affect the complexity of the spermatheca (number of spermathecal tubules) in this snail. However, the possibility that individuals in high-density populations store sperm from more different mating partners than those in low-density populations remains to be examined.

Leisler's bat Nyctalus leisleri was studied at sites around Bristol and Kent in southern Britain. Its diet was studied by faecal analysis, and habitat use was monitored by radio-telemetry and time-expanding bat-detectors. The diet, which varied between the two sites and also with the season, consisted primarily of small Nematoceran Diptera plus smaller numbers of Coleoptera and Lepidoptera. Foraging ranges were relatively large – bats flew a mean maximum distance of 4.2 km from the roost. Minimum area convex polygons enclosed an average of 7.4 km2, but were up to 18.4 km2. Bats significantly preferred foraging in areas of woodland and along scrub-lined roads in Kent, but over pasture around Bristol. Urban and arable areas were avoided at both sites. Bat-detector transects showed a significant preference for bats to forage along woodland margins.

We compared the underwater vocalizations of harp seals Pagophilus groenlandicus Erxleben, 1777 recorded during the breeding season at three locations: Jan Mayen Island (north of Iceland); Gulf of St Lawrence; and the ‘Front’ ice east of Labrador. The three herds shared 17 call types. The Jan Mayen herd had one call type not found in the Gulf or Front. One of the Gulf and Front call types was not found at Jan Mayen. Based on ANOVA post hoc pairwise comparisons between locations, the three herds exhibited a similar number of within-call type differences in duration, number of elements, start pitch and end pitch. There were no differences in proportional usage of call types between the Gulf and Front herds but both differed in a similar manner from those of the Jan Mayen herd. These findings support tagging studies that indicate that the Gulf and Front herds may be interbreeding and both are reproductively isolated from the Jan Mayen herd. We found no evidence of acoustic adaptation to the site-specific ice and environmental conditions associated with the three study locations.

Many individual nocturnal common spiny mice Acomys cahirinus and diurnal golden spiny mice A. russatus in the field are found missing all or part of their tails. Possibly, this is a predator avoidance mechanism. A 25-month field study revealed that at Ein Gedi (Israel) percentage tail-loss is 63% in male and 44% in female golden spiny mice, and 12% in male and 25% in female common spiny mice. Tail loss is significantly more common in golden spiny mice than in common spiny mice, possibly reflecting differences in predation risk or predator efficiency between the different microhabitats used by these species and in their different activity times. However, inter- and intraspecific aggressive interactions may also account in part for this pattern. Few significant differences in longevity, body mass, or reproductive condition were found between tailed and tail-less spiny mice, suggesting an advantage to tail-less individuals. Histological sections revealed a plane separating the skin layer from the underlying muscles and vertebrae, facilitating loss of the skin with little bleeding. The remainder (muscles and bone) is later chewed off by the mouse. A survey of published cases of tail loss in rodents revealed that this phenomenon occurs in at least 35 species and has evolved separately in eight rodent families, with no clear pattern in systematics, geography, or habitat use.

We examined the effect of a brood-size manipulation on the foraging effort and chick rearing of known-age great skuas Catharacta skua. Young birds were expected to refrain from increasing reproductive effort and opt for a strategy of brood reduction, while old birds were expected to increase effort and rear more young. Increasing brood size led to an increase in foraging effort and brood neglect. Enlarged broods had a lower mean survival rate, but similar growth rates to one- and two-chick broods. Parents increased foraging effort to maintain chick growth rates at the expense of brood defence. This was associated with higher conspecific predation of enlarged broods. Foraging effort and chick feeding rate decreased with adult age. Younger adults increased foraging time in an attempt to satisfy the nutritional demands of the chicks, while older birds maintained a similar effort for all brood sizes. Younger adults achieved a lower fledging success despite their higher provisioning rates. Younger birds synchronized foraging and guarding duties less well, and so left the chicks unattended more often than older birds. As a consequence, their chicks suffered higher levels of conspecific predation. Defence of chicks through pair co-ordination and aggression was thus an important component of successful breeding for great skuas.

The demography and life-history traits of a population of the lacertid lizard Podarcis bocagei in north-west Spain were investigated. Most of the conclusions presented are based on mark–recapture studies carried out over a 2-year period. Reproductive characteristics are similar to those reported for other temperate-climate lacertids. Clutch size, egg size and hatchling size (snout–vent length, SVL) are all positively correlated with the mother's SVL. Only large females lay more than one clutch per year. Growth rate is highest in young animals and declines gradually with age. In both sexes, sexual maturity is reached between the ages of 1 and 2 years. Again in both sexes, the probability of survival was fairly constant over the lifespan. Considering the study period as a whole, there was no significant between-sex difference in survival probability. Among adults, the probability of survival was higher in winter than during other periods, but the differences were not statistically significant. The individuals of the study population are sedentary, making only short movements even when periods of up to 2 years are considered (the mean distance moved between marking and recapturing 18–24 months later was 15.7 m, maximum 45.6 m). On average, immature individuals move further than adults, and adult males move further than adult females. Estimated population density (all individuals) dropped from 1574 ha-1 during the winter of 1989/90 to 1327 ha-1 during the winter of 1990/91. The decline in population density over the study period was also reflected in the estimated net replacement rate for the population (0.85, i.e. considerably less than one), and is probably attributable to colonization of the study site by plants (reducing suitability as a habitat for P. bocagei). Estimated mean generation time was 2.09 years.

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.

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).