Investigations on the pigments of the Apus cancriformis (Bosc.) (Crustacea : Branchiopoda)

Summary 1.The presence of pigments in Branchiopoda of an intense brown colour - Apus cancriformis (Boss.) was studied. 2.In extracts separated by means of column and thin-layer chromatography, the following carotenoids were identified: \gb-carotene, y-carotene, echinenone, canthaxanthin, lutein and xanthophyll.Synonym Trops cancriformis     

Comparison of the hatching process of the tadpole shrimps Triops cancriformis and Lepidurus apus lubbocki (Notostraca) and its relation to their distribution in rain-pools in Israel

Rain-pool habitats are gradually disappearing in Israel as a result of agricultural and urban development. Present and past records of notostracan distribution here reveal a difference in the occurrence of Triops cancriformis and Lepidurus apus lubbocki, the former rather rare, and support the suggestion that species of Triops are more thermophilic than Lepidurus, with optimal hatching temperature 8–12°C higher. The limited distribution of T. cancriformis in Israel may be partly attributed to sub-optimal temperatures (<20°C) in early winter.All populations of T. cancriformis in Israel were monosexual female. Resting Notostraca eggs float and become exposed to light, needed for hatching, and to warm day-time temperatures at the water surface which enhance embryonic development. Exposure to higher temperatures may be particularly important for the thermophilic T. cancriformis in Israel, where deep water temperatures in early winter are often below hatching values.     

Predation in a temporary pond with special attention to the trophic role of Triops cancriformis (Crustacea: Branchiopoda: Notostraca)

Temporary ponds are described as environments with a low predation pressure. Notostracans inhabit these types of ponds, and some populations acquire a high proportion of larger individuals, whose feeding behaviour is mainly predatory. The predation nature of Triops cancriformis is not widely accepted, because its diet is still partly controversial. We analysed the diet of one population of T. cancriformis in a Mediterranean temporary pond (Espolla pond, NE Iberian peninsula) to evaluate its predation behaviour. The gut content of the individuals bigger than 10 mm is mainly composed of detritus, plant fibres and microcrustaceans (cladocerans, ostracods and copepods). The prey number increases with the body size of individual T. cancriformis as previously described. Sex-biased predation was observed for one copepod prey, but not for the other. Predation pressure in that community was monitored along six hydroperiods as the percentage of predator biomass (not only T. cancriformis) in relation to the non-predator biomass. The proportion of predator biomass is high, and this contrasts with the low predation pressure expected for a temporary system with short hydroperiods.     

Population genetics and reproductive strategies of two Notostraca (Crustacea) species from winter ponds in Israel

Fluorescent-amplified fragment length polymorphism (FAFLP) fingerprinting assay was used to compare the genetic diversity within and between tadpole shrimps (Notostraca) populations of Lepidurus apus (n=7) and Triops cancriformis (n=2) from rain pools in Israel. Each ephemeral water body has revealed a unique fingerprint pattern with an entailed genetic drift between nearby ponds. High similarity of genotypic diversity within each geographic area led to three clusters of water bodies, north, south and center of Israel. FAFLP assays on several newly hatched individuals of T. cancriformis revealed high identity amongst kin, as compared to L. apus where newly hatched from the same maternal source showed high diversity. Results indicate that T. cancriformis populations from Israel are probably parthenogenetic as indicated by clonal structures. The higher genetic variability in the L. apus populations and in laboratory-hatched specimens indicates the existence of sexual reproduction.     

Gene flow and Andean uplift shape the diversification of Gasteracantha cancriformis (Araneae: Araneidae) in Northern South America

The Andean uplift has played a major role in shaping the current Neotropical biodiversity. However, in arthropods other than butterflies, little is known about how this geographic barrier has impacted species historical diversification. Here, we examined the phylogeography of the widespread color polymorphic spider Gasteracantha cancriformis to evaluate the effect of the northern Andean uplift on its divergence and assess whether its diversification occurred in the presence of gene flow. We inferred phylogenetic relationships and divergence times in G. cancriformis using mitochondrial and nuclear data from 105 individuals in northern South America. Genetic diversity, divergence, and population structure were quantified. We also compared multiple demographic scenarios for this species using a model‐based approach (Phrapl ) to determine divergence with or without gene flow. At last, we evaluated the association between genetic variation and color polymorphism. Both nuclear and mitochondrial data supported two well‐differentiated clades, which correspond to populations occurring on opposite sides of the Eastern cordillera of the Colombian Andes. The final uplift of this cordillera was identified as the most likely force that shaped the diversification of G. cancriformis in northern South America, resulting in a cis‐ and trans‐Andean phylogeographic structure for the species. We also found shared genetic variation between the cis‐ and trans‐Andean clades, which is better explained by a scenario of historical divergence in the face of gene flow. This has been likely facilitated by the presence of low‐elevation passes across the Eastern Colombian cordillera. Our work constitutes the first example in which the Andean uplift coupled with gene flow influenced the evolutionary history of an arachnid lineage.     

Morphological Reassessment of <Emphasis Type="Italic">Triops cancriformis</Emphasis> Bosc (Crustacea: Branchiopoda: Notostraca) Population from Kashmir,India with Comments on the Distribution of the Species in India

Triops cancriformis was reported first from India in 1871 and has been subsequently shown to occur in different regions of the country. In this paper, we have morphologically re-examined the Triops cancriformis population from Kashmir from where this species was first reported. We have compared some morphological traits of our T. cancriformis population with a few closely related species. The result shows that the Kashmir population is more similar to the typical non gonochoric Triops cancriformis in morphology. From literature records, we show that T. cancriformis has a peculiar distribution in India with no record of occurrences below 23°N. We also highlight the 125 years of history of T. cancriformis records from India.     

Sexual and Cleaning Behavior and Related Morphology in the Genus Cerocoma (Coleoptera: Meloidae)

The study of sexual behavior has been largely utilized in phylogenetic analyses of Meloidae beetles. Sexual behavior of the tribe Cerocomini is almost unknown, even though the genus Cerocoma shows the most striking sexual dimorphism in the family. In this paper, the sexual behavior of five species, C. (Cerocoma) adamovichiana, C. (C.) graeca, C. (C.) schaefferi, C. (Metacerocoma) schreberi, and C. (M.) prevezaensis, is described. The cleaning behavior of this genus, previously unknown, is also discussed. A morphological analysis by scanning electron microscopy of sexually dimorphic anatomical features of antennae, maxillary palpi, and forelegs, involved in cleaning and sexual activities, is carried out.     

Feeding strategy of two sympatric anostracan species (Crustacea)

The transport rate of chalk, clay particles and algal cells (Scenedesmus sp.) through the digestive tract of Streptocephalus torvicornis and Branchipus schaefferi is described under experimental conditions. Differences in transport rate as well as in the degree of digestion at a fixed particle density of algae were found. In S. torvicornis, the transport rate is higher and the digestion of algae lower than in B. schaefferi. These differences might reflect trophic differences related to niche partitioning in these sympatric species. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterization of dinucleotide microsatellite loci in the living fossil tadpole shrimp Triops cancriformis (Crustacea Branchiopoda Notostrace)

Five dinucleotide markers were obtained from a microsatellite genomic library of the tadpole shrimp Triops cancriformis. The number of alleles at each locus was low (maximum three alleles) but all loci were polymorphic. The presence of null alleles could not be disregarded. Heterozygosity levels were indicative of selfing in the studied populations whose real sexuality will be further tested using these markers.     

Ultrastructural observations on the oogenesis of Triops cancriformis (Crustacea,Notostraca)

Summary The first stages of the oogenesis of Triops cancriformis have been studied. At the outset the oocyte is smaller than the nurse cells. Meiosis begins with typical synaptonemal complexes. The significance of these complexes and of some other peculiar structures of germ cells, i.e., pore complexes and annuli within the nucleus, and annulate lamellae within the cytoplasm are discussed. The morphofunctional uniformity of some cytoplasmic structures (annulate lamellae, concentrically arranged ER, and yolk globules) in the oocyte as well as its nurse cells is also discussed.     

pH-related Hatching Success of Triops cancriformis (Crustacea: Branchiopoda: Notostraca)

Six different pH ranges were tested for the hatching rate of Triops cancriformis cysts. Cumulative hatching numbers approach to approximately 50% of cysts. The highest hatching rates, co-occurring with the shortest hatching times, were recorded in the neutral range. No hatching took place at pH values 9 and above. This corresponds with the most frequent habitats of this species, snowmelt pools of river flood plains as well as aestival pools caused by heavy rainfalls. Occurrences in sodic alkaline pans can be explained by relatively low pH values at the time of inundation.     

The formation of the nervous system during larval development in Triops cancriformis (Bosc) (crustacea,Branchiopoda): An immunohistochemical survey

We provide data of the development of thenervous system during the first five larval stages of Triops cancriformis. We use immunohistochemical labeling (against acetylated α‐tubulin, serotonin, histamine, and FMRFamide), confocal laser scanning microscopy analysis, and 3D‐reconstruction. The development of the nervous system corresponds with the general anamorphic development in T. cancriformis. In larval stage I (L I), all brain parts (proto‐, deuto‐, and tritocerebrum), the circumoral connectives, and the mandibular neuromere are already present. Also, the frontal filaments and the developing nauplius eye are already present. However, until stage L III, the nauplius eye only consists of three cups. Throughout larval development, the protocerebral network differentiates into distinct subdivisions. In the postnaupliar region, additional neuromeres and their commissures emerge in an anteroposterior gradient. The larval nervous system in L V consists of a differentiated protocerebrum including a central body, a nauplius eye comprising four cups, a circumoral nerve ring, mandibular‐ and postnaupliar neuromeres up to the seventh thoracic segment, each featuring an anterior and a posterior commissure, and two parallel connectives. The presence of a protocerebral bridge is questionable. The distribution of neurotransmitters in L I is restricted to the naupliar nervous system. Over the course of the five stages of development, neurotransmitter distribution also follows an anteroposterior gradient. Each neuromere is equipped with two ganglia innervating the locomotional appendages and possesses a specific neurotransmitter distribution pattern. We suggest a correlation between neurotransmitter expression and locomotion. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Male occurrence in Austrian populations of Triops cancriformis (Branchiopoda, Notostraca) and ultrastructural observations of the male gonad

Abstract. Recent reports of occasional males in Austrian populations of Triops cancriformis have promoted interest in an analysis of the ultrastructure of the male gonad. It appears as a double thick and well‐defined tubular structure running along the midgut, inside the hemocoel. It is composed of two portions: the wall and the lumen. The former is made up of germ cells that are widespread and intermixed with somatic cells. The lumen is ～200 μm wide and acts as the collecting site of spermatids and sperm. The germ cells are recognizable by their rounded appearance and by the occurrence of exceptionally long synaptonemal complexes in their nuclei. Their maturation implies a volume elongation and an aggregation in a characteristic “cyst” arrangement. The cysts migrate towards the lumen, where they break open, releasing spermatids and sperm. At the end of this process the lumen is filled with maturing gametes. The sperm have very condensed chromatin nuclei and partially reduced cytoplasm where the most striking features are the axoneme and strewn microtubules together with evident pseudopodia. Our morphological data support the full functionality of males in T. cancriformis. However, further work on gametogenesis, distribution of sexes, and genetic analysis of breeding experiments are needed to reach a fuller understanding of the role of males in middle and northern European populations of this species.     

Heart ultrastructure in Branchinecta paludosa,Artemia salina,Branchipus schaefferi,and Streptocephalus sp. (Crustacea,Anostraca)

Summary The heart ultrastructure of the anostracan Crustacea Branchinecta paludosa, Artemia salina, Branchipus schaefferi, and Streptocephalus sp. is essentially similar. All lack an endocardium and an epicardium, and the heart wall consists of a single layered myocardium. Only in the posterior end of the heart does the myocardium form a tube. In the remaining, anterior part of the heart, the myocardium forms a trough. The dorsal edges of this trough are firmly attached to the basement membrane of the epidermis, which thus forms the lid of the trough.The Z-bands of the sarcomere are diffuse, and H- and M-bands were not seen. Interior couplings are as a rule found at Z-levels.This work was supported by grants from the Norwegian Research Council for Science and the Humanities     

Retention, capture and consumption of experimental prey by orb-web weaving spiders in coffee plantations of Southern Mexico

This study focuses on the predatory capacity of four sympatric species of web- building spiders that inhabit coffee plantations in Southern Mexico: Gasteracantha cancriformis, Cyclosa caroli, and the morphologically similar species pair Leucauge mariana and L. venusta which were considered as one species group. The retention capabilities of the webs of these species and the incidence of prey capture and consumption were measured using eight types of insect prey belonging to the orders Coleoptera (1 species), Hymenoptera (3), Diptera (2) Lepidoptera (1) and Homoptera (1). The different characteristics of each prey such as body weight, body size, defensive behaviour, etc., were recorded. The incidence of prey retention, capture and consumption were significantly higher in G. cancriformis than in any of the other species. The lowest rates of retention, capture and consumption were observed in C. caroli, while L. mariana/venusta were intermediate in their predatory capabilities. Significant negative correlations between prey size and percent consumption were detected in L. mariana/venusta and in G. cancriformis; in both cases, large prey were less likely to be immediately consumed than small prey items. The results can be interpreted in the light of the morphological characteristics of the spiders. G. cancriformis possesses long legs and a carapace and appeared to have few difficulties to manipulate all types of prey. In contrast, C. caroli showed lesser abilities to manipulate and subdue aggressive prey items, perhaps due to the short leg length and unprotected body of this species. The consumption of prey items may be related to the predatory strategy of each spider. G. cancriformis constructs a new web every morning and prey storage was never observed. The absence of prey storage behaviour could explain why this species consumes prey soon after capture. In contrast, C. caroli constructs a permanent web and stores captured prey on a stabilimentum that may explain the very low incidence of immediate consumption of prey observed in this species.     

R2 dynamics in Triops cancriformis (Bosc, 1801) (Crustacea,Branchiopoda, Notostraca): turnover rate and 28S concerted evolution

The R2 retrotransposon is here characterized in bisexual populations of the European crustacean Triops cancriformis. The isolated element matches well with the general aspects of the R2 family and it is highly differentiated from that of the congeneric North American Triops longicaudatus. The analysis of 5′ truncations indicates that R2 dynamics in T. cancriformis populations show a high turnover rate as observed in Drosophila simulans. For the first time in the literature, though, individuals harboring truncation variants, but lacking the complete element, are found. Present results suggest that transposition-mediated deletion mechanisms, possibly involving genomic turnover processes acting on rDNAs, can dramatically decrease the copy number or even delete R2 from the ribosomal locus. The presence of R2 does not seem to impact on the nucleotide variation of inserted 28S rDNA with respect to the uninserted genes. On the other hand, a low level of polymorphism characterizes rDNA units because new 28S variants continuously spread across the ribosomal array. Again, the interplay between transposition-mediated deletion and molecular drive may explain this pattern.     

Ultrastructural observations on the oogenesis of Triops cancriformis (Crustacea,Notostraca)

Summary Each ovarian follicle of Triops cancriformis is four-celled; these cells (one oocyte and three nurse cells) are interconnected by cytoplasmic bridges. In the course of differentiation, the nurse cells are early recognizable; they increase in size more than the oocyte and their nuclei contain many nucleoli. For the first time in Arthropoda, yolk globules are reported to be present in nurse cell cytoplasm; these globules arise from the smooth endoplasmic reticulum. The functional significance of the intercellular bridges and the trophic role of the nurse cells are discussed.The authors are grateful to Dr. Bruno Sabelli for his support and to Mr. Francesco Monte for his technical assistance     

Follicle duct cell ultrastructure and eggshell formation in Triops cancriformis (crustacea,notostraca)

Electron microscopy of the cells of the follicle duct of Triops cancriformis shows that the follicular ducts are lined by a single-layered epithelium which also produces the eggshell material. The cytoplasm is rich in rough endoplasmic reticulum that synthesizes the eggshell material which subsequently aggregates into preformed vacuoles. Newly formed spheres of eggshell material are then excreted into the lumen. At the end of vitellogenesis the oocytes descend toward the longitudinal oviduct and pass through the eggshell material which fills the follicle ducts. The production of the eggshell and its chemical composition in some Phyllopoda are compared. The paper discusses the relationship between the eggshell construction and the reproductive biology of the population.     

Identification,expression, and molecular evolution of microRNAs in the “living fossil” Triops cancriformis (tadpole shrimp)

MicroRNAs have been identified and analyzed in various model species, but an investigation of miRNAs in nonmodel species is required for a more complete understanding of miRNA evolution. In this study, we investigated the miRNAs of the nonmodel species Triops cancriformis (tadpole shrimp), a “living fossil,” whose morphological form has not changed in almost 200 million years. Dramatic ontogenetic changes occur during its development. To clarify the evolution of miRNAs, we comparatively analyzed its miRNAs and the components of its RNAi machinery. We used deep sequencing to analyze small RNA libraries from the six different developmental stages of T. cancriformis (egg, first–fourth instars, and adult), and also analyzed its genomic DNA with deep sequencing. We identified 180 miRNAs (87 conserved miRNAs and 93 novel candidate miRNAs), and deduced the components of its RNAi machinery: the DICER1, AGO1–3, PIWI, and AUB proteins. A comparative miRNA analysis of T. cancriformis and Drosophila melanogaster showed inconsistencies in the expression patterns of four conserved miRNAs. This suggests that although the miRNA sequences of the two species are very similar, their roles differ across the species. An miRNA conservation analysis revealed that most of the conserved T. cancriformis miRNAs share sequence similarities with those of arthropods, although T. cancriformis is called a “living fossil.” However, we found that let-7 and DICER1 of T. cancriformis are more similar to those of the vertebrates than to those of the arthropods. These results suggest that miRNA systems of T. cancriformis have evolved in a unique fashion.