Sexual dimorphism in chelicerae,forelegs and palpal traits in two burrowing wolf spiders (Araneae: Lycosidae) with sex-role reversal

Allocosa alticeps and Allocosa brasiliensis are two sex-role-reversed spiders. Females locate males and initiate courtship. Copulation occurs inside male burrows and after copulation the males deliver their burrows to the females. We explored the occurrence of differences in morphological traits related to sex roles in both Allocosa species and compared the results with two non-burrowing wolf spiders with typical sex roles. We measured the length of the foreleg's tibia-patella and the chelicerae. Scanning electron micrographs of palpal tarsus distal sections were taken. Males showed higher values than females in all the traits considered. Adult and penultimate males lacked true claws compared with juveniles and females, but showed modified spines. The palpal organ was more proximal to the tibia compared with the non-burrowing lycosids considered in this study. Spines and palpal organ location could be associated with more effective digging. We discuss how natural and sexual selection could interact on morphology in this scenario.     

Reproductive biology of Limnoria chilensis: another boring peracarid species with extended parental care

Several boring peracarid species engage in extended parental care with parents tolerating small juveniles in their burrows, but only anecdotal observations have been reported from boring isopods of the genus Limnoria. The isopod Limnoria chilensis Menzies is frequently found in holdfasts of the macroalgae Macrocystis pyrifera (L.) C. Agardh and Durvillea antarctica (Chamisso) Hariot. In the present study, holdfasts of D. antarctica that harboured L. chilensis were carefully dissected in order to examine the association pattern of reproductive females and small juveniles. In most infested holdfasts, L. chilensis reached very high densities of 43.7 ± 3.9 (mean ± SE) individuals cm^?2 (range: 0–90 individuals cm^?2). The overall sex ratio (females:males) was close to unity (1.2). Male size varied between 1.5 and 2.6 mm body length (BL) and female size between 1.5 and 3.6mm BL. The percentage of reproductive females was low (19.7% of all females), and only the largest females (>2.6 mm BL) were reproductive. Embryo numbers ranged between six and 19 per female and a significant correlation between female BL and the number of embryos was found. Several females were found with small juveniles (0.8–1.2 mm BL) in the terminal end of their burrows. On several occasions, aggregations of similar-sized juveniles (1.0–1.5 mm BL) in their own burrows were found near a female burrow, indicating that these juveniles initiated their first individual burrows from within the maternal burrows. Some females with small juveniles in the terminal end of their burrows were either accompanied by males or they were ovigerous, indicating that they may have been in the process of producing a second brood. The fact that juveniles build their first burrows in the protection of female burrows suggests that such small juveniles have not yet developed full boring capacity. Extended parental care in this (and other boring) peracarid species represents a mechanism facilitating high juvenile survival rates. Given the highly local recruitment, it is suggested that the reproductive biology of this isopod has strong implications for Its population biology.     

A not so natural history of the tarantula Brachypelma vagans: Interaction with human activity

We describe the structure of a population of Brachypelma vagans (Ausserer, 1875) in relation to the intensity of human activity and report characteristics of the burrows in Campeche, Mexico. During September and October 2003, we established sampling areas in five different classes of vegetation type/land use: mature forest (MF), secondary forest (SF), backyard (BY), and a football field divided into corner area (FC) and goal area (FG). The densities of spiders and the proportion of different age/gender classes of individuals on the sites were compared. Morphological data among adults and juveniles were contrasted, and differences in morphology between juveniles were tested according to land use class. We compared the nearest distances between neighbouring burrows and between burrows and trees. Also, we studied the orientation of the burrows, and compared the diameter of the burrow entrance. Brachypelma vagans was found exclusively in the open areas with densities that ranked from 0.02 to 0.1 individuals per square metre, being among the highest ever reported for Theraphosidae. However, there was a negative relationship between density and intensity of human activity. The population of this tarantula shows segregation in occupation of space. Females occupied exclusively the backyards, whereas juveniles occupied sites according to their stage of development. The youngest juveniles occupied the backyards, while the pre‐adults occupied the football field. The distance between burrows was highly variable at all the sites. However it tended to be shorter in the backyards. The orientation of burrows was in all sites preferentially directed northwards. The diameter of the burrow entrances was a relatively good indicator of the sex and age of its occupier, and related almost directly to the dimension of the body. This study provides better knowledge of the structure of B. vagans populations in a human‐modified environment and gives new information on the natural history of these spiders.     

Extended parental care in two endobenthic amphipods

Extended parental care is described for two endobenthic amphipods which inhabit the estuarine soft-bottoms along the Gulf of Maine. The juveniles of both amphipod species, Leptocheirus pinguis and Casco bigelowi, remain in the burrow of their mother after they hatch from the brood pouch. Several consecutive clutches of L. pinguis can inhabit the female's burrow simultaneously, but in C. bigelowi there is always only one clutch of juveniles in the burrow of the female. Larger juveniles of L. pinguis start building their own small tubes at the bottom of the female's burrow. Casco bigelowi females increase the size of their burrows during the time when the juveniles grow. The juveniles of both species leave the female's burrow at about half adult size. The major tasks of female L. pinguis and C. bigelowi during the time of extended parental care is to irrigate and maintain the deep burrow. It is hypothesized that extended parental care in L. pinguis, C. bigelowi and other tube/burrow-living peracarids is a mechanism to protect small offspring from epibenthic predation.     

Another migid in the wall: natural history of the endemic and rare spider Calathotarsus simoni (Mygalomorphae: Migidae) from a hill slope in central Argentina

A population of Calathotarsus simoni Schiapelli and Gerschman (1975) was discovered on a hillside in the Ventania system, Argentina. Our objectives were to quantify burrow density, record burrow morphology and door characteristics and describe the micro-habitat. We counted 57 burrows and report a density of 0.01 burrows/m². Aggregation indices suggest that burrows are aggregated under some area plots but more evenly distributed on others. The trapdoor is thick and rigid with bevelled edges connected to the entrance rim by a narrow articulated hinge. Two egg sacs from females were obtained and data on eggs and spiderlings are presented. We registered six burrows of an undetermined species of Actinopus. While a few specimens of Actinopus sp. were found inhabiting this hillside, the highest proportion of burrows belonged to C. simoni. Spider diversity on the hillside shows the predominance of Linyphiidae, Nemesiidae and Gnaphosidae. One juvenile of C. simoni was captured using pitfall traps.     

Juvenile Sphaeroma quadridentatum invading female-offspring groups of Sphaeroma terebrans

Female isopods Sphaeroma terebrans Bate 1866 are known to host their offspring in family burrows in aerial roots of the red mangrove Rhizophora mangle. During a study on the reproductive biology of S. terebrans in the Indian River Lagoon, Florida, USA, juvenile S. quadridentatum were found in family burrows of S. terebrans. Between September 1997 and August 1998, each month at least one female S. terebrans was found with juvenile S. quadridentatum in its burrow. The percentage of S. terebrans family burrows that contained juvenile S. quadridentatum was high during fall 1997, decreased during the winter, and reached high values again in late spring/early summer 1998, corresponding with the percentage of parental female S. terebrans (i.e. hosting their own juveniles). Most juvenile S. quadridentatum were found with parental female S. terebrans, but a few were also found with reproductive females that were not hosting their own offspring. Non-reproductive S. terebrans (single males, subadults, non-reproductive females) were never found with S. quadridentatum in their burrows. The numbers of S. quadridentatum found in burrows of S. terebrans ranged between one and eight individuals per burrow. No significant correlation between the number of juvenile S. quadridentatum and the numbers of juvenile S. terebrans in a family burrow existed. However, burrows with high numbers of juvenile S. quadridentatum often contained relatively few juvenile S. terebrans. The majority of juvenile S. quadridentatum found in family burrows of S. terebrans were smaller than the juvenile S. terebrans that were cared for by their mothers. The results indicate that the presence of S. quadridentatum in S. terebrans family burrows may negatively affect the duration of extended parental care in S. terebrans. It is not known why parental female S. terebrans are not able to discriminate against juvenile S. quadridentatum. Possibly, the fact that the two species are closely related facilitates S. quadridentatum sneaking into S. terebrans family burrows.     

The occurrence of facultative paedomorphosis in a lacustrine population of the Pyrenean newt (Calotriton asper): morphology and age structure

Facultative paedomorphosis is a common polyphenism in newts where two alternative phenotypes can coexist: metamorphs and paedomorphs (mature with larval traits, i.e. retaining gills). This phenomenon has been reported in some lacustrine populations of the Pyrenean newt (Calotriton asper). The morphology and life-history traits were studied in a lacustrine population of this species with the occurrence of facultative paedomorphosis. The results showed that 24.3% of adults retained gills at different levels of reabsorption and had a smoother skin compared with the other populations, which were fully metamorphic. The body size and shape showed significant sexual differences, with males being larger than females. The presence of paedomorphic traits also affected the body size and shape, revealing a complex pattern of growth in which metamorphic adults were larger than paedomorphs. The age structure was different between sexes, with a median age of 10.5 and 7 years and longevity of 19 and 14 years in males and females, respectively. Considering each sex separately, the age structure was not significantly different between metamorphic and paedomorphic newts. In addition, metamorphosed and branchiate juveniles were found with a maximum age of 13 and 20 years, respectively. Remarkably, long-lived larvae with an exceptional individual of 18 years were found, which has not previously been reported in any other newt species. The mechanisms that can explain the evolution of paedomorphosis are complex and comprise the interaction of multiple factors related to the cost of reproduction and growth.     

Expulsion and consumption of male ejaculates by promiscous female Euxesta eluta and Euxesta mazorca (Diptera: Ulidiidae)

While expulsion of male ejaculates by the females after copulation has been reported for various animal groups, expulsion followed by consumption of the expelled ejaculate is a rare behaviour outside spermatophylax-producing orthopterans. Among Diptera, this behaviour has been reported for a few species of Piophilidae, Empididae and Ulidiidae. Here we report on its occurrence among Euxesta eluta and Euxesta mazorca (Diptera: Ulidiidae). We also attempt to characterize the mating system of E. eluta in order to facilitate future hypothesis testing to understand the behavioural factors leading to the evolution of this peculiar behaviour. For this, courtship sequences, copulation duration, frequency of ejaculate expulsion and subsequent consumption, and latency to ejaculate expulsion for both E. eluta and E. mazorca were recorded. The time of sexual maturation, the time window of sexual receptivity during the day, and the mating frequency and variance in mating success for males and females (degree of polygamy) were determined for E. eluta. Both E. eluta and E. mazorca males engaged in elaborate courtship sequences involving visual and tactile displays before copulation. Females of both species almost invariably expelled and consumed ejaculates after copulation. Female E. eluta, required a 6- to 9-day period feeding on protein and sugar before becoming sexually receptive. Reproductive activity occurred continuously over the day with an early morning and late afternoon peak. Both males and females could mate multiply, with multiple partners over a 2-h observational period. Sexual network analysis revealed that some males and females had greater mating success than others. Ejaculate consumption appears to be widespread in the genus Euxesta. It is possible that females obtain nutrients from this behaviour while exerting some control over egg fertilization.     

Behaviour and habitat of Neohela monstrosa (Boeck, 1861) (Amphipoda: Corophiida) in Norwegian Sea deep water

There are few in situ observations of deep-sea macrofauna, due to the remoteness of this ecosystem. Visual surveys conducted for marine management by MAREANO, (marine area database for Norwegian waters) and the petroleum industry (by SERPENTS, scientific and environmental remotely operated vehicle partnership using existing industrial technology) have provided unique material of visual information from large areas in the Norwegian Sea. The distribution, density and behaviour of the deep-sea amphipod Neohela monstrosa (Boeck, 1861) is described based on videos and samples from the Norwegian Sea. This amphipod is common on mud bottoms at 200–2181 m depth in the area. Dense communities were found in stands of the arctic sea pen Umbellula encrinus at more than 1000 m depth where temperatures were below 0° C. The mean density of N. monstrosa observed for larger areas was 4/100 m² but densities of 15–36 individuals per m² were found in local patches. It is domicolous which is characteristic of the superfamily Corophiida and digs burrows in soft muddy bottoms primarily by using large shovel-like gnathopods to scoop the sediment out. The amphipod was observed pushing and rolling sediment balls out of its burrow, which were probably held together with amphipod silk. It digs out an upper 3 to 4 cm wide burrow with a horizontal side burrow a couple of centimetres down. Neohela monstrosa appears to feeds on newly settled detritus that it collects from the surface sediment through the use of its long antennae while the burrow is mainly used for protection against predators such as demersal fish. Newly released juveniles are probably kept in the burrow for protection. Based on the local high density of N. monstrosa together with its habit of making long burrows, we suggest that there is significant bioturbation associated with the presence of N. monstrosa in deep sedimentary habitats of the Norwegian Sea, which likely provides an important ecosystem function.     

Morphometric structure and allometry profiles of the giant red shrimp Aristaeomorpha foliacea (Risso, 1827) in the eastern Mediterranean

The relative growth of body parts, such as abdomen, uropod, scaphocerite, telson, rostrum, and the third pereiopod of males and females of the giant red shrimp (Aristaeomorpha foliacea, Risso, 1827) was studied in samples from the Greek Ionian Sea (eastern Mediterranean) in 1999–2000. These were related to carapace length, sex and size of individuals. A length–weight relationship was also obtained. In general, a negative allometry of swimming appendages (uropod, scaphocerite), abdomen (related to metabolic processes), and length of the third pereiopod (involved in walking ability) was observed in both sexes. Growth of the telson was positively allometric in females and negatively allometric in males. Asynchronous growth of the male rostrum was also noted. Appendages were proportionally longer in juveniles than in adults of both sexes. A strong negative allometry between length–weight for both sexes was shown, and females were heavier than males in all sampled months.     

Age,body size and growth pattern of Argenteohyla siemersi pederseni (Anura: Hylidae) in northeastern Argentina

In this study we analysed the body size, age structure, age at maturity, longevity and growth pattern of Argenteohyla siemersi pederseni in north-eastern Argentina using skeletochronological methods. Body size was sexually dimorphic; females were significantly larger and heavier than males, regardless of age. As A. s. pederseni is an explosive breeder with only one reproductive episode per year, we assumed that each Line of Arrested Growth (LAG) observed was equivalent to one period of decreasing growth, LAGs reflecting a direct estimation of individual age. The minimum number of LAGs counted was two for males and three for females, but there was no sexual difference in longevity. The von Bertalanffy's growth coefficients (K) were higher in males than in females for both size and body mass. Females had a lower growth rate than males, took longer to reach the minimum maturation size, and were older and larger at reproduction.     

Diurnal colour change in a sexually dimorphic trait in the Andean lizard Anolis heterodermus (Squamata: Dactyloidae)

Sexual dimorphism in body size, shape and colour is widespread in lizards as well as in other taxa. In the context of sexual selection, these sex differences are commonly manifested as exaggerated male traits, which are selected by females to assess the quality of males. However, differences in sex by environment interactions can also lead to sexual dimorphism. The genus of Anolis lizards is particularly well known for sharp sexual dimorphism in dewlap colour and size; however, this is not the case in all anole species. Using digital image analyses, I assessed the existence of sexual differences in the diurnal change in colour and size of a conspicuous patch on the tail of the lizard Anolis heterodermus Duméril 1851. Results showed that the tail patch of both males and females changed in colour, but not size, from red to blue throughout the day in a similar fashion. This process took almost half a day to complete and occurred in the absence of conspecifics, suggesting that the change itself may not have an active role in social communication. However, the colour patches of males were consistently larger. The cause of the substantial variation in colour and size of the tail patch of A. heterodermus is still unknown and deserves more research. This study highlights the importance of continuous wildlife observations to identify life history traits that may be important in animal behaviour but are challenging to observe in nature.     

An ontogenetically stable sexual character in a montane agamid,Salea horsfieldii Gray, 1845 (Reptilia: Agamidae) from Nilgiris,India

Many agamid lizards are known to show sexual dimorphism in body shape, colour and ornamentation or a combination of these traits. Adult males of Salea horsfieldii have a discontinuous dorsal crest at the nuchal region, which is a sexually dimorphic character. However, there is no information about the age or size at which this dimorphic ornamentation develops and if the species exhibits sexual shape dimorphism (SShD). The authors studied the morphology of S. horsfieldii and found that its ornamentation is an ontogenetically stable character present in all males, including juveniles. Seven morphological characters were measured to determine if they exhibited SShD at adult and juvenile stages. Analysis of covariance was used to identify differences in morphology between sexes. The results show that only adults exhibited SShD, but not juveniles. Adult males had larger head and foot lengths in comparison to females of the same size. Larger head length in adult males is a sexual fitness trait, which increases bite-force during intra-sexual combats. Although the presence of sexually dimorphic ornamentation right from the juvenile stage is rare in agamids, S. horsfieldii is an exception . The role of sexually dimorphic ornamentation at juvenile stages remains unknown and requires further investigation.     

Habitat use by the Persian onager,Equus hemionus onager (Perissodactyla: Equidae) in Qatrouyeh National Park,Fars, Iran

Iran’s Persian onager populations are critically endangered. This study of their natural history in Qatrouyeh National Park provides insights for enhancing their conservation. The population as a whole is greatly affected by weather. Wind, rain and cold drive populations from the plains to the valleys of hill-valley habitats. Vegetation features and water also influence habitat use, but differently for different sex and reproductive classes. Females with juveniles use plains with high-quality vegetation, whereas females without young and solitary territorial males choose those of intermediate quality. Females with young foals are also found closest to watering points. Future translocation of Persian onagers will only succeed if prospective habitats have sufficient hill-valley refuges and enough plains with winds to moderately hot conditions. Sufficient plains supporting high-quality vegetation near water for lactating females must co-exist with plains of moderate-quality vegetation that attract females without young, so reducing crowding and competition.     

An imperfect imago? Post-mating loss of iridescent scales in Cheimas butterflies may change female from attractive to cryptic (Lepidoptera: Nymphalidae: Satyrinae)

Adults of both sexes of Cheimas opalinus (Staudinger), a Satyrinae butterfly occurring in the cloud forests of the Venezuelan Cordillera de Mérida, have simple wing colour patterns, dark brown dorsa marked by one conspicuous element, large greenish-blue patches in the discal area of the hind wing. It was observed that in young, freshly emerged females these patches are frequently absent. They fade away and eventually disappear during mating and nuptial flights when brushed out by lateral movements of the male’s hind wing put between folded female hind wings. The falling off of the scales is made easy because they do not adhere to the wing as firmly as brown background scales due to their particular folded extremities. We speculate that this process is related to the fitness of the females. Prior to mating, blue-green patches are advantageous because they attract the attention of the opposite sex and enhance the chances of successful mating. After mating they lose their sexual role. Females without the blue-green patches become cryptic. Thus, they are less apparent not only for the males, which helps them avoid sexual harassment, but also for potential bird predators. Additionally, the loss of blue reflecting scales may speed up the warming up of the abdomen and egg maturation. In the males, positive role of the patches (signalling), and negative (bird attraction), is balanced during their entire life span, and they fade gradually due to regular usage of wings scaling in flight. Our hypothesis is supported by morphological, optical, experimental and statistical analysis in which we used 509 individuals of both sexes. A similar ratio of young (with undamaged wing) females with or without blue patch was recorded, whereas in the males no individuals without any trace of blue patch were reported, and a correlation of age (wing damage) and gradual fading off of the patch was demonstrated. Such an adaptation involving an active change of the appearance of adults, i.e. colour patterns related to sexual selection, has not been reported previously in Lepidoptera.     

Behavioural ecology of Australian gall thrips (Insecta,Thysanoptera)

Collections, observations and experiments were used to investigate the behavioural ecology of gall thrips (Thysanoptera: Phlaeothripidae) in New South Wales and Queensland, Australia. Data are presented on aspects of gall morphology, male and female morphology, behaviour, life cycles, and sex ratios for six gall-forming species, five species of inquilines (invaders that do not form galls), and one genus that uses secretions to glue phyllodes (modified petioles) together. During gall foundation on phyllodes of Acacia pendula, females of Kladothrips rugosus Froggatt fight other females to the death, males fight other males to the death, and one female or one adult of each sex remains alive within the gall to breed. In addition to the live adults, half of newly found galls contained dead bodies of from one to 13 males and females, which were apparently killed in fights. In Oncothrips tepperi Karny, which forms galls on Acacia oswaldii, single females found new galls, and females engage in lethal fighting during the period from gall initiation until closure. First-generation broods of Oncothrips tepperi comprise winged males and winged females with a sex ratio of about 1:6 female biased. Each gall also contains several wing-reduced adults with larger forelegs than winged adults, which probably either fight among themselves or defend their siblings from gall invaders. Adults of Oncothrips tepperi breed in the galls for two or more generations, whereas in all of the other species studied on Acacia only one generation occurs in a gall. Females of the inquiline Koptothrips flavicornis invade young, first-generation galls of Oncothrips tepperi, kill the foundling female, and produce their own offspring. Single females of Oncothrips antennatus (Moulton) form galls on Acacia aneura, and apparently do not fight. Winged females of Oncothrips antennatus have smaller forelegs, relative to their body size, than do winged females of Oncothrips tepperi. In Onychothrips arotrum Mound and Onychothrips tepperi (Uzel), single females from galls on Acacia aneura. In each species, females engage in lethal fighting during gall initiation. The sex ratio of Onychothrips arotrum broods is about 1:18 female biased. The inquiline Csirothrips watsoni Mound invades galls of Onychothrips arotrum, apparently after most or all of the offspring have left, and breeds inside. Females of this inquiline will kill live Onychothrips arotrum inside the galls, and they apparently plug gall entrances with cast O. arotrum exuviae. Iotatubothrips crozieri Mound and Crespi is involved in the formation of large, woody galls on stems of Casuarina, perhaps in association with a microorganism. They breed in these galls for many generations. Galls contain several to thousands of individuals, and the adult sex ratio is about 1:4 female biased. Adults of the inquilines Thaumatothrips froggatti and Phallothrips houstoni Mound and Crespi invade these galls, kill the Iotatubothrips adults, and breed therein. The Iotatubothrips occasionally attempt, ineffectually, to fight off the invaders, and they apparently make partitions within the gall to protect themselves from takeover. Adults of Lichanothrips spp. glue phyllodes of Acacia harpophylla together using eggs and patches of secretion, and they breed in the resultant narrow space. Xanothrips xantes Mound breed in these spaces after the Lichanothrips have left. Fighting in Kladothrips rugosus, Oncothrips tepperi and Onychothrips tepperi involves two adults rearing up head to head, sparring with their enlarged, armed forelegs raised, and attempting to grasp and hold their opponent with their forelegs and drive their sharply pointed fore-tarsal teeth into their opponent's body. Females of Onychothrips arotrum also grasp, stab and kill with their forelegs, but they have not been observed to rear up head to head. Three of the inquiline species, Csirothrips watsoni, Thaumatothrips froggatti and Phallothrips houstoni, kill the original gall inhabitants by extending their forelegs directly in front of their bodies, tilting their heads back, remaining in this position for variable periods of time, and sharply pulling their armed fore tibiae towards the fore femora when their victim is near. Inquilinism in gall thrips may have evolved from lethal intraspecific fighting. Certain aspects of behaviour and morphology in Australian gall thrips, such as high prevalence of lethal fighting, gall ‘plugging’ in Csirothrips watsoni, attempted gall defence and apparent formation of partitions in Iotatubothrips crozieri, and the presence of wing-reduced adults in Oncothrips tepperi, indicate that these species exhibit some of the most complex behaviour thus far discovered in Thysanoptera.     

Observations on the tube-building behaviour of the marine amphipod Cymadusa filosa Savigny (Crustacea: Ampithoidae)

The study reports on the tube-building behaviour of the corophioidean amphipod, Cymadusa filosa Savigny on two algae, Sargassum binderi Sonder and Ulva lactuca Linnaeus, based on experimental protocols using specimens in aquaria and in petri dishes. Cymadusa filosa was observed to construct open-ended, uniform diameter cylindrical tubes using amphipod silk, to bind together faecal pellets, detritus and fronds of Sargassum binderi or Ulva lactuca. Detailed studies of tube-building behaviour were carried out in petri dishes containing Ulva lactuca, using isolated specimens (5–13 mm in size) of different sexes for a period of one and a half months. Both males and females constructed tubes, and an average of four tubes were built by adults in 15 days. Females with young in the brood pouch did not construct new tubes following juvenile release. Juveniles were observed to build tubes using detritus and faecal material only within hours of being released from the brood pouch. The tubes of juveniles were either built on the walls of their mother's tubes or on an algal mass put together by the mother. There was a highly significant positive correlation between body length and tube length in males and females. There was no significant difference in the rate of tube length increase relative to body size between males and females, between males less than or more than 10 mm, or between females of less than or more than 10 mm. Tube-sharing was also observed between males and females.     

Habitat use patterns within the home range of pygmy rabbits ( Brachylagus idahoensis ) in southeastern Idaho

Pygmy rabbits ( Brachylagus idahoensis ) are a small sagebrush ( Artemisia tridentata ) obligate lagomorph found within the Great Basin of northwestern United States. Because of its reliance on sagebrush, this species is thought to be experiencing a major range reduction as a result of loss of sagebrush habitat. To aid in conservation of this species, we need to better understand its use of the sagebrush environment. We estimated summer home range use patterns by relocating 5 radio-collared pygmy rabbits (3 females and 2 males) over a 24-hour cycle. We then compared soil texture, shrub density, height, and canopy cover between areas close to burrow entrances and areas of high use and low use. Mean home range sizes of female and male rabbits were 37.2 and 67.9 ha, respectively. Rabbits had disproportionate amounts of time (68.4% ± 9.1, s￣x ) and travel (63.0% ± 5.7, s￣x ) in areas within a 60-m radius of their burrows. Soil texture did not differ among the 3 areas, but shrub density, specifically big sagebrush, and forb density were significantly higher close to the burrow than in the high- and low-use areas. We conclude that pygmy rabbits are possibly burrow obligates and that their abundance and distribution are likely limited by available burrow sites.     

Mating behaviour and spermatophore transfer in the shrimp Heptacarpus pictus (Stimpson) (Decapoda: Caridea: Hippolytidae)

Summary

Heptacarpus pictus, a small caridean shrimp inhabiting the low intertidal of southern and Baja California, breeds during the winter, spring, and summer months. Fall is a period of growth. Life span of an individual does not exceed 18 months, with fish predation as the most likely source of mortality.

Females are multiple brooders, carrying developing embryos concomitant with increase in ovary size. Hatching of larvae is followed by a moult, after which the female is attractive to males and receptive to copulation. A distance pheromone does not appear to be involved in attraction of males to females. Males apparently respond to a non-diffusible substance on the exoskeleton of newly moulted females.

Precopulatory behaviour is absent. Copulation can be divided into a series of relatively stereotyped events. Female rejection of the male or his spermatophore is the chief cause of unsuccessful matings.

Males deposit the spermatophore on the underside of the female's first abdominal segment. Sperm packets are formed upon extrusion from the male's genital openings, and are composed of a mucoid material in which sperm are mixed. The glutinous spermatophores adhere to the female's smooth abdominal sternite.

The endopods of pleopods 1 and 2 of the male are different in shape, size and setation from homologous rami of females and juveniles. Endopods of pleopod 1 possess a distally located appendix interna, absent in juveniles and females. An anteriorly projecting process, the appendix masculina, is located on the endopod of pleopod 2 in males. Experiments were performed which showed that these modifications insure proper deposition of spermatophores. Males which had the copulatory rami removed did not transfer spermatophores as successfully as normal males.

Transfer of the spermatophore from the male to the female is a result of the interplay of male pleopods 1 and 2 during copulation. The large expanded abdominal pleurae of females prevent the male's genital opening from contacting her abdominal sternite. Thus, the male's anterior pleopods have become modified to lift the emitted spermatophore from his genital orifices to the first abdominal sternite of the female.