Carapace ontogeny of the bromeliad dwelling ostracod Elpidium bromeliarum Müller, 1880 (Crustacea: Ostracoda)

Ostracods have discontinuous development, marked by ecdyses, and determinate growth. Ontogenetic studies have suggested a pattern of nine postembryonic stages (eight juvenile phases and the adult) for the main freshwater ostracod superfamilies Cypridoidea, Cytheroidea and Darwinuloidea. However, cases of a supposed extra moult in the adult stage have been proposed for some ostracod species, which would amount to 10 postembryonic growth stages. One such example is Elpidium bromeliarum Müller, 1880, a cytheroidean that inhabits tank-bromeliads. The present study is aimed at investigating the ontogenetic development of E. bromeliarum using width and length measurements, as well as carapace and appendage morphology in order to test the existing hypothesis of an additional growth stage in adults of this species. Our results revealed nine postembryonic growth stages (eight juvenile and the adult), with sexual dimorphism beginning its expression in the last juvenile stage. Thus, the ontogenetic development of E. bromeliarum agrees with the overall pattern observed for podocopid ostracods and the hypothesis of 10 postembryonic growth stages was not corroborated. We argue that the inability to differentiate juveniles from adults, or different species from one another, may have misled to the assumption of an additional moult in E. bromeliarum.     

Geographic variation in body size and sexual size dimorphism in the giant spiny frog Paa spinosa (David, 1875) (Anura: Ranoidae)

We describe the spatial pattern of variation in body size and sexual size dimorphism in the giant spiny frog, Paa spinosa (David, 1875). The study also aims to identify potential factors responsible for geographic morphological variation in the frog. The results indicate that primary production, which positively correlates with precipitation and summer temperature in China, had an important effect on body size of P. spinosa, whereas Bergmann's rule was more efficient to explain the influence of average minimum temperature in January. The species was sexually dimorphic for body size and body shape: the body size, jaw length and forelimb length of males were significantly larger than those of females. Furthermore, the degree of sexual size dimorphism varied geographically, but the relationship between the geographic variation of sexual size dimorphism and the climate was complex. Specifically, absolute sexual size dimorphism was positively correlated with the increased ambient temperature and decreased precipitation.     

Characterisation of burrow architecture under natural conditions in the sand-dwelling wolf spider Allocosa brasiliensis

Allocosa brasiliensis (Petrunkevitch, 1910) is a wolf spider that constructs silk-lined burrows along the coastal sand dunes of Argentina, Brazil and Uruguay. This species shows a reversal in typical sex roles and sexual size dimorphism expected for spiders. Females are the smaller and mobile sex, which initiates courtship at the male burrow entrance. Mating occurs in the male burrow, and when it ends, the male leaves and the female stays inside. Females prefer to mate with those males showing longest burrows, so burrow dimensions would be under strong sexual selection pressures. Previous studies in the laboratory indicated that male burrows are longer than those of virgin females, which were described as simple silk capsules. Preliminary observations suggested that juvenile burrows presented differences from those of adults; however, detailed observations of A. brasilienisis burrow characteristics at the field were lacking. The aim of this study was to characterise the burrows of adults and juveniles of A. brasiliensis under natural conditions. We recorded the dimensions of burrows inhabited by males, females and juveniles (n = 30 for each category) and created beeswax moulds that reflected burrow shape. Juveniles inhabited tubular burrows with two branches and two openings; on the contrary, adults were found in tubular burrows with a single entry. Males and females inhabited burrows of similar length and width, but those of juveniles were shorter and narrower. We discuss the results and their possible functional explanations according to the selective pressures expected for each developmental stage and sex.     

The taxonomic utility of the male upper lip morphology in the ostracod genus Parapolycope (Crustacea), with descriptions of two new species

The male copulatory organ is recognized as a significant character for species taxonomy in the sexually reproducing Ostracoda. However, the genus Parapolycope has a simply shaped male copulatory organ consisting almost entirely of just the copulatory duct. In this study, two new species, Parapolycope psittacina sp. nov. and Parapolycope uncata sp. nov., are described, and the characters that have taxonomic value were examined based on a morphological comparison of these new species. Carapace size, shape and surface ornamentation, and the male upper lip are valuable characteristics for species identification. The morphology of the male upper lip, especially, exhibited a remarkable sexual dimorphism, which might have a function associated with reproductive isolation. http://www.zoobank.org/urn:lsid:zoobank.org:pub:D2F2F902-C496-4861-8872-813BC310AD9F     

Population dynamics and reproduction of the hermit crab Calcinus gaimardii (Anomura: Diogenidae) at Inhaca Island,southern Mozambique

The population dynamics and reproduction of Calcinus gaimardii were studied at Inhaca Island, southern Mozambique. Crabs were sampled monthly from January to December 2003 in order to assess abundance, size distribution, sex ratio, reproduction and juvenile recruitment. Calcinus gaimardii is sexually dimorphic in relation to size, with males reaching larger size than females. Sex ratios were female‐biased during most months of the study period. Females were more abundant in the intermediate size classes while males outnumbered females in the largest ones. Reproduction took place year‐round with peaks of breeding activity between August and October. Likewise, juvenile recruitment was continuous for both sexes with high intensity in winter (May and June). Egg number increased with female size.     

A remarkable new species of scuttle fly (Diptera: Phoridae) whose larvae infest chickpea root nodules in India

Metopina ciceri sp. nov. is described on the basis of males with reduced wings, fully winged females, blind females with reduced wings, pupae and larvae. The larvae infest the root nodules of the chickpea, Cicer arietinum L. The blind-morph females are considered to be congeneric with the type species of the genus Typhlophorina Silvestri and this genus is synonymized with Metopina. The males, if procured in isolation, would have been assigned to a separate genus. The evolution of sexual dimorphism and dimorphic females in M. ciceri is discussed in relation to a speculative scenario involving juvenile hormone and heterochrony. It is also speculated that dispersal is undertaken by the sighted fully-winged female morph only. These speculations and the question of whether the infestation of C. arietinum by M. ciceri affects yield remains to be investigated.     

Diet and sexual dimorphism of the desert iguana, Dipsosaurus dorsalis, from Sonora, Mexico

We examined the diet and sexual dimorphism of the desert iguana, Dipsosaurus dorsalis, from Sonora, Mexico. The diet consisted primarily of vegetation, with insect material contributing little to the overall volume of the diet. Plant matter was restricted to leaves and seeds. Animal prey consisted mostly of ants, termites, and beetles. Males and females did not differ significantly in snout–vent length, head length, or head width. These results confirm that in general D. dorsalis is herbivorous and not sexually dimorphic through much of its range. Examinamos la dieta y dimorfismo sexual de la Iguana del Desierto, Dipsosaurus dorsalis, en Sonora, México. La dieta consistió principalmente de vegetales, con insectos contribuyendo poco al volumen total de ésta. La materia vegetal estuvo restringida a hojas y semillas. Las presas animales consistieron principalmente de hormigas, termitas, y escarabajos. Machos y hembras no difirieron significativamente en longitud hocico cloaca, longitud de la cabeza, o ancho de la cabeza. Estos resultados confirman que en general D. dorsalis es una especie herbívora que no presenta dimorfismo sexual en la mayor parte de su intervalo de distribución.     

The juvenile stages of Parastacus brasiliensis (von Martens, 1869) (Crustacea,Decapoda, Parastacidae)

The family Parastacidae consists of the freshwater crustaceans popularly known as crayfishes or crawfishes. Only the genus Parastacus occurs in Brazil, with P. brasiliensis (von Martens, 1869) endemic to the state of Rio Grande do Sul in southern Brazil. Parastacids have direct development, ecloding as juveniles. In laboratory‐reared specimens, juvenile I stage is similar in morphology to the adult, with no setae on most appendages, absence of uropods and presence of a hook on the dactyl of pereiopods 4 and 5. The juvenile II retains juvenile I characteristics but has more setae, which are more varied in morphology. The juvenile III possesses setae as the adults, fully formed uropods and the hooks on pereiopods 4 and 5 are substituted by an apical rectilinear dactylus.     

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.     

Spawning behaviour and sexual dimorphism in the North American cyprinid fish Notropis leedsi,the bannerfin shiner

The spawning behaviour and sexual dimorphism of the little known North American cyprinid fish, Notropis leedsi, is described based on observations made in laboratory aquaria. Notropis leedsi is a crevice spawning species, a trait characteristic of members of the subgenus Cyprinella. Males establish breeding territories through ‘mock battles’ and defend them by chasing away intruding males or, at times, through threat displays or ‘mock battles’. Although wild-caught males are significantly larger than females, sexual dimorphism is more pronounced in the colour pattern and fin size, especially the dorsal and anal fins.

The modes of spawning behaviour in the genus Notropis are reviewed. The relationship between the promiscuous mating system (polybrachygamy), the crevice spawning mode, and sexual dimorphism in N. leedsi are discussed in relation to current notions regarding sexual selection.     

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.     

Juvenile development and growth patterns in the mud crab Eurytium limosum (Say, 1818) (Decapoda,Brachyura, Xanthidae) under laboratory conditions

The post‐larval development of the mud crab Eurytium limosum was studied under laboratory conditions by using the offspring of ovigerous females collected at the Comprido River mangrove, SP, Brazil. The first crab stage is fully described and the juvenile development, until crab stage 10, is examined with emphasis on morphological change, sexual differentiation and growth patterns. The carapace of the first crab stage is nearly square as observed in other xanthids, becoming similar to adults only at stage 15. The sexes can be distinguished from stage four, based on the number of pleopods and their morphology. While the intermoult period increases, the moult percentage decreases at each stage. The abdominal allometric growth is sex‐dependent, with males showing a negative (b?=?0.71) and females an isometric (b?=?0.95) relative growth pattern. Male gonopods undergo a positive allometric growth, and their shape changes remarkably until sexual maturity. The cheliped dentition can be observed after stage 4. Regardless of sex, most crabs have a molariform right cheliped, which is thought to aid the handling of asymmetric prey such as gastropods.     

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.     

First-instar morphology and sexual dimorphism in the gall-inducing scale insect Apiomorpha Rubsaamen (Hemiptera: Coccoidea: Eriococcidae)

Sexual dimorphism among crawlers of the scale insect family Eriococcidae is reported for the first time. The general morphology of crawlers of the gall-inducing genus Apiomorpha (Eriococcidae) is presented and sexual dimorphism described. Sexual dimorphism appears to be associated with differential dispersal and settling-site preference of the sexes during the crawler stage. First-instar males of the A. pharetrata and A. munita species-groups settle only on the galls induced by their mothers or, in the case of A. munita, also galls of nearby females, whereas female crawlers disperse. Female crawlers of all species of Apiomorpha, and male crawlers of most species, are well suited for air-borne dispersal. It is suggested that sexual dimorphism among crawlers of Apiomorpha, and some other scale insects, is the result of loss or reduction of those morphological features associated with dispersal. In addition, male crawlers of some species of Apiomorpha have sensory structures which may assist in the detection of sex-specific settling sites.     

Relative growth and sexual dimorphism of the South Atlantic hermit crab Loxopagurus loxochelis (Anomura,Diogenidae) from Ubatuba,Brazil

Some morphometric relationships and biometric aspects were studied in the hermit crab Loxopagurus loxochelis (Moreira, 1901) with the purpose of describing its relative growth and finding the size where sexual maturity is reached. Specimens were collected monthly from September 1995 to August 1997 in the Ubatuba region using double-rig trawl nets. A total of 1084 specimens (625 males and 459 females) was analysed. In this species, sexual dimorphism is particularly evident in chela dimensions. Differences between males and females were found in the left propodus length versus cephalothoracic shield length (CSL) and wet weight (WW) versus CSL relationships. Males showed a high positive allometry in chela growth, while females were close to isometry/negative allometry. The size at which a clear differentiation occurred in the growth of the propodus length and in the increase in weight of males and females was between 4.5 and 6.0mm CSL, suggesting that size at which sexual maturity is reached.     

Ciplakastacus gen. nov., a primitive genus of Leptastacidae (Copepoda,Harpacticoida) from the Mediterranean coast of Turkey

Both sexes of Ciplakastacus mersinensis gen. et sp. nov. (Copepoda, Harpacticoida, Leptastacidae) are described in detail based on intertidal material collected from the Mediterranean coast of Turkey (Mersin Province). Plesiomorphic character states displayed by the antenna and P1–P2 indicate Ciplakastacus diverged before the crown group Leptastacidae diversified. The new genus is placed in a basal clade (currently encompassing Archileptastacus and Meloriastacus) defined by eight synapomorphies: (1) caudal ramus with strongly developed seta I flanked by two elongate spinules; (2) caudal ramus with posteriorly directed spinous outgrowth of outer distal corner; (3) caudal ramus seta III vestigial; (4) P5 exopod and baseoendopod forming single plate in both sexes; (5) P2–P4 exp‐3 with one outer spine; (6) dorsal posterior margin of anal somite bilaterally serrate; (7) rostrum triangular or bell‐shaped, and (8) sexually dimorphic ornamentation on the anal somite. Within this clade Ciplakastacus appears most closely related to Meloriastacus on account of the shared presence of the extremely elongate second antennulary segment, an allobasis on the antenna, the strongly reduced accessory seta on the maxillipedal endopod, the subcylindrical sternal process between the maxillipeds and P1, and paired laterodorsal, posteriorly directed, serrate extensions on the anal somite. Both genera can be distinguished from each other by P5 morphology (both sexes), armature of P4 enp‐2 and abdominal hyaline frill structure. The phylogenetic relationships between the basal taxa of the Leptastacidae are briefly outlined.     

Intersexuality in benthic harpacticoid copepods in the Firth of Forth,Scotland

Following the discovery of a high frequency of intersexuality in Paramphiascella hyperborea in the vicinity of Edinburgh's long-sea sewage outfall, the seabed off the Edinburgh coast was surveyed in spring and autumn to examine the distribution of intersexuality in relation to the sewage outfall. From these and previously collected samples it was found that intersexuality was common in both P. hyperborea and Stenhelia gibba and also present in two species of Halectinosoma. Intersexuality was widespread along the Edinburgh coastline, being recorded up to 10 km from the discharge but there was no evidence for a correlation between intersex frequency and proximity to the discharge. Possible reasons for the high level on intersexuality in the Firth of Forth are discussed. Most intersexes displayed similar secondary sexual characters, with the sexually dimorphic prosome appendages taking the female form, the 5th leg intermediate between male and female and the 6th leg and urosome segmentation male in character.