Hatching phenology,life history and population dynamics of the Oriental clam shrimp Eulimnadia indocylindrova Durga Prasad and Simhachalam with notes on phenology patterns in the Spinicaudata

We studied the natural history, hatching phenology and egg bank composition of the Oriental spinicaudatan clam shrimp Eulimnadia indocylindrova Durga Prasad and Simhachalam using both field studies and ex situ sediment rehydration. Field observations revealed that hatching began very early (1–2 days) after inundation, and continued for about 5 days. Mature adults could be observed by 10 days, and they survived up to 16 days. The population showed a largely hermaphrodite-biased sex ratio (male:hermaphrodite 1:3) observed over three years, with a decrease in number of males throughout the hydroperiod. Both amphigenic and monogenic hermaphrodites were observed. The total lifetime fecundity recorded was about 300 eggs laid in multiple clutches. The egg bank composition showed a high proportion of intact eggs, indicative of predictable hydrations and low sediment adversity. Hatching began on the first day post-inundation for all successive cyclical hydration treatments, with peak hatching on days 2 and 3. Hatching rate was highest (57% of total hatching in successive cycles) for the first hydration, decreasing subsequently for the further hydrations. Hatching duration decreased with successive hydrations and was the longest (around 7 days) for the first hydration. Maximum hatching (93%) occurred in the first 10 days for the continuous hydration treatment. Overall, the total emergence of nauplii in successive hydrations was larger than that observed for the continuous hydration treatment, indicative of a risk-spreading strategy across hydroperiods. Early and concentrated naupliar emergence, along with decreased hatching durations for successive cycles, was observed for all the hydrations. A survey of literature revealed a general lack of data on hatching phenology of clam shrimps, particularly from tropical and sub-tropical regions. Based on the available data, it appears that hatching patterns, particularly high, early hatching fractions, are commonly observed in Spinicaudata species, and do not seem to differ much across biogeographical regions.     

Reproduction,development and parental care in two direct‐developing flatworms (Platyhelminthes: Polycladida: Acotylea)

Variations in reproductive modes, egg production, and the effects of parental care on hatching success are compared between Pleioplana atomata and Imogine zebra. Pleioplana atomata transfers sperm via true copulation, whereas I. zebra dermally impregnates spermatophores onto the dorsal surface of partners. Pleioplana atomata lays up to 750 large eggs over a 6‐week period, and I. zebra individuals lay up to 1346 small eggs in 12 days. Female fecundity is positively correlated with body size in both species. Developmental time lines are temperature‐dependent, and juvenile worms hatch after 3 and 6 weeks for I. zebra and P. atomata, respectively. Covering of egg masses by the adult is observed for both species and although this parental care is not necessary for egg development or hatching, it plays a significant role in the hatching success of P. atomata. In I. zebra, parental covering of egg masses may play a role in eggshell development.     

Ancestrular morphology in cyclostome bryozoans and the quest for phylogenetically informative skeletal characters

Cyclostomes are an ancient order of bryozoans with more than 500 living species. Traditionally, cyclostome taxonomy has depended almost entirely on characters of the calcareous skeletons of mature colonies. However, the taxonomic distribution of these characters is largely incongruent with well-supported molecular phylogenetic trees, implying the need for major revisions if cyclostome taxonomy is to reflect phylogeny. While far more taxa must be sequenced to ascertain their molecular relationships, there is also a need to discover morphological characters that can be used to support molecular clades, not least to allow these clades to be inferred among fossil cyclostomes for which molecular data will never be available. Here we survey the skeletal morphology of the first-formed part of the skeleton – the protoecium of the founding zooid (ancestrula) – in a variety of Recent and well-preserved fossil cyclostomes, motivated by the recent discovery of a morphologically disparate molecular clade that can be distinguished by protoecial characters. The distribution of pseudopores on the protoecium is shown to vary between species, with eight patterns recognizable, offering a new source of skeletal characters in both living and fossil taxa. However, the patterns seem not to be fully congruent with the cyclostome molecular tree and more data and analyses are required before these patterns can be used to recognize cyclostome clades.     

Composition and abundance of periphyton and aquatic insects in Sierra Nevada, California, stream

The species composition of periphyton and benthic insect communities and abundances of common taxa (&;gt;0.1&;#37; of individuals) were examined during snow-free months in Convict Creek, a permanent snowmelt- and spring-fed stream in the Sierra Nevada of California. The communities were highly diverse. The most abundant taxa in the periphyton were diatoms ( Achnanthes minutissima, Cocconeis placentula lineata, Cymbella microcephala, C. sinuata, Fragilaria construens, F. crotonensis , Navicula spp., Synedra acus , and S. rumpens ), except in late spring and summer when several seasonal blue-green algae ( Chamaesiphon incrustans, Lyngbya spp. and Oscillatoria spp.) are at their maximum densities. Most common periphyton taxa vary systematically in abundance with season, but relative abundances of taxa also appear to be influenced by streambed scouring and by concentrations of ambient nutrients. Data on population densities and length frequencies of larval and nymphal stages of common benthic insects and occurrences of pupal and adult stages were examined to determine life history patterns. Taxa hatching in winter and spring and abundant as immatures in late spring include ephemeropterans ( Epeorus longimanus, Drunella flavilinea , and Caudatella heterocaudata ), plecopterans ( Calineuria californica, Doroneuria baumanni, and Pteronarcys princeps ) and dipterans ( Cryptolabis sp.). Common taxa hatching in late spring or summer are the plecopteran Malenka ( californica? ) and the trichopterans Arctopsyche grandis and Rhyacophila acropedes . Several bivoltine and multivoltine ephemeropterans ( Baetis devinctus and B. tricaudatus ) and dipterans ( Simulium spp. and Chironomidae) have summer cohorts. Taxa hatching in late summer or autumn and most abundant in autumn include ephemeropterans ( Baetis spp., Ephemerella infrequens, Epeorus dulciana, Ironodes lepidus , and Paraleptophlebia pallipes ), trichopterans ( Hydropsyche oslari, Lepidostoma spp., Glossosoma califica, Micrasema sp., Brachycentrus americanus, Neophylax sp., and Rhyacophila vaccua ) and dipterans ( Antocha monticola, Pericoma sp., and Chironomidae). Major recurring events that may influence life history patterns and structure of the benthic insect community are (1) near-freezing, nighttime winter water temperatures and occasional anchor ice, (2) a prolonged period of high discharge in late spring and early summer (3) a brief summer, and (4) a prolonged period of moderate stream discharge in autumn when the substratum is stable and food is abundant.     

On the anatomy of a new species of Oxypolella (Nemertini) and further notes on Oxypolella bergendali Cantell 1975

The anatomy of a new species of heteronemertean from the Mediterranean, Oxypolella banyulensis sp. nov., is described and illustrated. The species is characterized by having a dermis comprising subepidermal longitudinal muscle fibres arranged in characteristic piles, a three-layered proboscis with four main regions, one ciliated pit in the frontal organ, two dorsal nerves and a thin inner circular muscle layer. Further notes on Oxypolella bergendali are given.     

Epibiontic communities on the freshwater shrimp Caridina ensifera (Crustacea,Decapoda, Atyidae) from Lake Poso (Sulawesi,Indonesia)

The epibiont communities of the freshwater shrimp Caridina ensifera, endemic to Lake Poso (Sulawesi, Indonesia), were analysed for the first time based on their morphological and biometrical characteristics and taxonomic position. Seven ciliated protozoans and a rotifer were examined: three suctorian ciliate protozoan species (Acineta sulawesiensis, Podophrya maupasi, and Spelaeophrya polypoides), three peritrichs (Zoothamnium intermedium, Vorticella globosa, and Cothurnia compressa), a haptorid (Amphileptus fusidens), and the rotifer species Embata laticeps. A mean number of 314.6 epibionts was found per shrimp specimen. The distribution of the epibiont species on the surface of the basibiont was recorded, to allow calculation of the density on the different colonized individuals of C. ensifera and on each anatomical unit of the shrimp. The most abundant species, Zoothamnium intermedium and Acineta sulawesiensis, were also the ones most widely distributed. The statistical analysis showed that Zoothamnium, Acineta, Podophrya, and Embata were the epibiont genera most widely distributed on the basibiont, and the pairs of epibiont genera Zoothamnium–Embata, Podophrya–Acineta, Spelaeophrya–Amphileptus, and Cothurnia–Vorticella followed a similar pattern of distribution. There was a significant difference between the distribution patterns of the different epibiont species on the shrimp. The analysis of the densities of the epibionts throughout the longitudinal axis of the shrimp showed a gradient from the anterior to the posterior end of the body, and a significantly different distribution of each epibiont species. Their colonization follows a certain pattern of behaviour, the species occupying the available substratum, with particular requirements of each functional group, but with a trend resulting in equilibrium among species and groups, compensating for diversity and density. The possible adaptations of the epibionts, as well as the colonization patterns are discussed.     

Caruncle in Megalomma Johansson, 1925 (Polychaeta: Sabellidae) and the description of a new species from the Eastern Tropical Pacific

The presence of a caruncle in the polychaete family Sabellidae is documented. It is placed dorsally above the mouth, between the dorsal lips, supported with hyaline cartilage constituted by a homogeneous eosinophilic matrix and it is innervated directly from the cerebral ganglion. The caruncle surface has four longitudinal ciliated bands; the cilia from the lateral bands are hypertrophied, wider distally, tongue‐like, forming a ciliated curtain or membranella. The genus Megalomma is emended based on the presence of a caruncle, a long dorsalmost radiolar pair, a high number of radiolar skeletal cells, and the presence of interramal eyespots. We describe a new species from Acapulco in the Tropical Eastern Pacific –Megalomma carunculata sp. nov. It has a caruncle, subtriangular ventral lappets, well developed dorsal pockets, compound eyes in all radioles, and interramal eyespots in the thoracic and abdominal segments.     

Activity and reproduction in Megalobulimus paranaguensis (Gastropoda,Eupulmonata): implications for conservation in captivity for a South American land snail

ABSTRACT

In South America, Megalobulimus includes a number of threatened species, as well the largest land snails on the continent. The activity patterns and reproductive aspects of this group have not been documented. This work describes the daily and seasonal activity patterns and reproduction of M. paranaguensis. We maintained specimens in the laboratory for one year, and we quantified their behaviour for one hour at four different times of the day (0 h, 6 h, 12 h and 18 h) during three days in four months (August, September, April and May). The number of postures, hatching rate, time of hatching since oviposition and mortality rate among juveniles for each month were also quantified. Megalobulimus paranaguensis was more active in August, and had a egg laying peak one month after. Fifty-one eggs were laid by 12 captive individuals throughout the year, with a mean value of 4.25 eggs per individual. The hatching rate was 80.39%, and the time of hatching since oviposition was 56.7 ± 4.3 days. In two eggs, we observed the presence of twins. The mortality rate among juveniles was low (9.30%) indicating that rearing land snails in captivity has the potential to be an important and viable tool for the management and conservation of these organisms.     

Strong phenological differences between two populations of a Neotropical funnel-web wolf spider

Comparisons of phenological patterns among populations within a species are uncommon in arachnids. Aglaoctenus lagotis is a wolf spider that lives in funnel-webs across South America. The aim of this study was to describe the phenological patterns of two distant populations of A. lagotis (central Argentina, CA, and southern Uruguay, SU). Individuals of each population were sighted along transects, every month for two years. The CA and SU populations differed in their phenological patterns (Wald χ² = 966.94, df = 66; p <0.001). The CA population showed a spring–summer unified reproductive season and immature individuals overwintered. SU showed the sexual period during autumn, the maternal period during spring–summer and the females, mostly mated, overwintered. These strong differences imply temporal isolation in mating possibilities between both populations. The differences encountered could be due to phenotypic plasticity or have a phylogenetic basis. Interpopulation studies of other features of A. lagotis would show whether they also vary, suggesting speciation.     

Zoogeographic affinities of the stoneflies (Plecoptera) of the Raft River Mountains, Utah

We examined faunal affinities of the Raft River Mountains using stoneflies (Plecoptera) as indicators. This island-like mountain range is isolated from other major mountain ranges in the Intermountain West by low-elevation, arid regions. Thirty-seven species were recorded from collections from 19 sites in the Raft River Mountains. Cluster analysis demonstrated the Raft River Mountain stonefly assemblage to be most similar to faunas of the Sawtooth and Wasatch mountains, and quite different from that of the Sierra Nevada. An analysis of the distribution patterns of each species, on a family-by-family basis, showed that the Raft River Mountains fauna consists mostly of species widespread in western North America. Most families were represented by at least 1 species whose distribution supports faunal affinities with regions to the north and west. Logistic regression of 6 long-distance dispersal factors against stonefly presence-absence data did not support long-distance dispersal as a viable means of colonization for the Raft River Mountains. This suggest that stonefly distribution patterns may be attributed to expansion and subsequent vicariance of suitable stonefly habitats during Pleistocene climatic oscillations.     

Molecular phylogenetic analysis of three groups of Asian epilachnine ladybird beetles recognized by the female internal reproductive organs and modes of sperm transfer

We determined partial sequences of the nuclear 28S ribosomal RNA gene (717 base pairs) and mitochondrial DNA NADH-dehydrogenase subunit 2 gene (535 base pairs) of 25 species of phytophagous ladybird beetles from Asia that comprise 16 species of the genus Henosepilachna and nine species of the genus Epilachna, and reconstructed the phylogenetic trees for each gene by the maximum parsimony and maximum likelihood methods. The estimated phylogenetic relationships were consistent with those obtained by the mode of sperm transfer and female internal reproductive system, and supported an earlier assumption that very similar elytral spot patterns of some sympatric members of epilachnine beetles evolved independently.     

Temporal organization patterns of epigean beetle communities (Coleoptera: Carabidae,Tenebrionidae) in different successional stages of eastern Mediterranean maquis

This two-year study explores the community structure and temporal dynamics of carabid and tenebrionid beetles in five eastern Mediterranean juniper maquis formations in relation to successional stage. Based on vegetation cover, density and soil pH, the successional stage in two of the sites (Crete, Cyprus) was an earlier state compared with the other three (Attiki, Naxos, Samos), as a result of intense goat grazing. Diversity indices and abundance distributions were compared using morphoecological surrogates of the taxa. Temporal dynamics were regulated more by cumulative species richness than by sharp phenological patterns. The higher values of niche pre-emption parameter and species turnover imply better adaptation of endemic tenebrionids to the rapid change of environmental conditions, compared with carabids. Significantly lower abundance and biomass, and higher evenness and temporal turnover for both families in Crete and Cyprus are ascribed to the reversed course of succession caused by overgrazing.     

Biogeographic regions of Central Argentina based on snake distribution: evaluating two different methodological approaches

Regionalization studies attempt to divide an area into regions by studying the distribution of its biota. Here we used snake distribution in Central Argentina to recognize distribution patterns, and then compared two methods (cluster analysis and endemism analysis) and the patterns found with previously defined regions. Both analyses recovered Chaco and, within Chaco, the subregion Chaco Serrano, as well as all the snake species that are threatened or range-restricted occurring only in the Chaco region, which has been severely deforested in the last decades. The Espinal region was not recovered by cluster analysis or NDM software, and may be considered an “impoverished” Chaco or a transition zone. The Pampas was only recovered by cluster analysis. NDM appears to be more robust than cluster analysis, whereas the latter seems to be very sensitive to sampling problems, sometimes identifying spurious areas or areas characterized by having no exclusive species.     

Comparing the effects of granivorous rodents on persistence of Indian ricegrass ( Oryzopsis hymenoides ) seeds in mixed and monospecific seed patches

In desert environments seeds are often heterogeneously distributed in small patches that vary in number of seed species and in seed density. Because seed harvest by rodents is often density dependent (a larger proportion of seeds is removed from high-density seed patches than from low-density patches), the proportion of residual or post-harvest seeds should be greater in low-density patches. In addition, seed preference can affect harvest. We tested whether the residual proportion of a highly preferred seed (Indian ricegrass, Oryzopsis hymenoides ) was less when in a seed patch with a 2nd species (mixed-species patch) than when in a monospecific seed patch. We predicted that the increased overall seed density due to the presence of 2 species in a patch would result in a lower residual proportion of ricegrass seeds in the mixed-species seed patches than in the monospecific patches. As predicted, the residual proportions of Indian ricegrass seeds were less each time ricegrass was paired with one of 6 other species in mixed-species patches. Similarly, the residual proportion of each of those 6 species was less when paired with ricegrass than when in a monospecific patch. We speculate on the potential implications of these results for the population dynamics of plant species and the physical structure of plant communities.     

Taxonomic revision of Ascidiacea (Tunicata) from the upper continental slope off north-western Australia

A collection of ascidians from 100–1000 m deep off the north-western coast of Australia has yielded 19 species, including one new, two possibly endemic to the north-western coast of Australia, four well-known Indo-west Pacific tropical species and 12 species known from the deeper waters of the western Pacific, of which 11 had not previously been recorded from off the western Australian coast or from other parts of the Indian Ocean. A third of these 12 species displays adaptations for a reduction in filter-feeding capacity, as do other known species from deeper slope and abyssal habitats. Nevertheless a connection with fauna of deep ocean basins of the Indian Ocean is not apparent at this stage. The full range of characters associated with species, genera and families are discussed, and those contributing to the identification of immature or mutilated specimens, as well as those relevant to an assessment of phylogenetic relationships, are emphasized.     

The size variable and allometric analysis in the barnacle genus Balanus

Size variables employed in field and laboratory studies on acorn barnacles usually vary with each investigation, making accurate comparisons of results among studies difficult. The relationship of a size index to individual weight or volume is either not known, or not reported. Evaluation of 15 morphometric variables by allometric analysis, using least-squares regression, multiple step-wise regression and ANCOVA, was performed on adults of 12 species of the cosmopolitan genus Balanus. Specimens represent variation in size, shell shape, and shell design thought to occur in the genus; only isolated, complete, undamaged individuals growing on planar surfaces were used. By significance testing, within and among species, total shell volume (VTS) and basal length (LBA) increase in constant proportion with total weight, but valve weight (WTV) and soma weight (TSO) do not. Regression statistics for log-linearized data permit a discussion of other attributes which characterize these variables.     

Observations on courtship,mating and sexual maturity in Portunus pelagicus (L., 1766) (Crustacea,Portunidae)

Summary

Larvae of Alpheus heterochaelis from North Carolina hatch from large eggs as advanced zoeae, usually moult three times, and exhibit almost no linear growth during a short (4 days at 25°c) larval development. Stage I lasts 6 hours at most and is sometimes skipped; III lasts about twice as long as II. Individuals simultaneously exhibiting characteristics of Stage III and the postlarva were occasionally seen. The three zoeal stages and postlarva are described in detail and illustrated. Stages in embryonic and juvenile development and the hatching process are briefly described.

An ‘extended’ pattern of larval development, characteristic of most alpheid species, is described in a general way, and the ‘abbreviated’ development of A. heterochaelis compared to it. At hatching, A. heterochaelis larvae bear rudimentary pereiopods and pleopods; other structures are at the same level of development in both patterns, but subsequent morphogenesis is faster in A. heterochaelis. Larval development of Synalpheus spp., some of which exhibit extreme abbreviation or direct development, is briefly described with reference to the A. heterochaelis pattern.     

An overview of the mite fauna (Acari) associated with eumenine wasps (Hymenoptera: Vespidae) found in Brazilian collections

ABSTRACT

Mites can be associated with other organisms as parasites, commensals, phoretic, among others, such as some Winterschmidtiidae that present cooperative relationships with solitary wasps (Eumeninae). These wasps have one or more cavities in their body surface that are capable of carrying mites, called acarinaria. Studies carried out in the northern hemisphere suggest that these relationships are species-specific. However, in South America, there are few studies in this field. Aiming to recognize and increase our knowledge of the species of solitary wasps from Brazil that are associated with mites, we examined 61 wasps belonging to 29 species and four genera from Brazilian museum collections. All of the specimens studied presented at least one type of acarinarium in their bodies. There were mites in all specimens of wasps, but not all of them were associated with an acarinarium. The mites belong to 11 different genera: six in Winterschmidtiidae (possibly cooperation relationships); one in Oplitidae (phoresy); one in Erythraeidae (parasitism); two in Acaridae (phoresy); and one in Histiostomatidae (phoresy). Detrended correspondence analysis and indicator species analysis were conducted to test the preference of the mite genera for species of wasp and for site (regions of the wasp’s body). These tests were significant only for the mite genus Vespacarus preferring Parancistrocerus wasp species and the metasomal acarinaria. Some of the mites did not have a specific host, and some wasps carried more than one species of mite, differing from the specific interactions reported for the northern hemisphere.