The effects of chromatin diminution on the pattern of C-banding in the chromosomes of Acanthocyclops vernalis Fischer (Copepoda: Crustacea)

Chromatin diminution is the loss of selected regions of pre-somatic cell chromosomes during early development, resulting in the removal of a large amount of the genomic DNA from the pre-somatic cells. In copepods, diminution is characterized by the formation of heterochromatically staining regions, or H-segments, which contain the chromatin to be lost. The removal of H-segments during diminution also must represent a major restructuring of the chromosomes which contained them. In order to examine the effects of diminution on the morphology and structure of the chromosomes, the C-banding technique was used. This procedure revealed that most C-bands present in the pre-diminution complement were absent in the post-diminution set. Additionally, in order to explore further the possible composition of the DNA contained in H-segments, a comparison, based on the relationship of C-bands to highly-repetitive DNA in chromosomes, was made between pre-diminution C-bands and H-segments. This comparison showed that not all H-segments are at chromosomal locations which produce a C-band, indicating that H-segments are perhaps not entirely composed of genetically inert DNA, as is currently supposed.     

The ecology and biology of Southeast Asian false spider crabs (Crustacea: Decapoda: Brachyura: Hymenosomatidae)

The false spider crabs of the family Hymenosomatidae are one of the most poorly known group of brachyuran crabs in Southeast Asia. This is largely attributed to their small size and cryptic behaviour. Despite the many studies of decapods in Southeast Asia, only eleven species of hymenosomatids are known. Of these, two genera and six species were only described in the last two years. From Singapore the largest number of species (five) has been reported probably because it has been the best explored, while from Thailand three species and Peninsular Malaysia two species are known. There are no published records of hymenosomatids from Borneo or Java. The hymenosomatid fauna is perhaps best known in Australia and New Zealand. It is anticipated that when proper collections are made and studies implemented, the Southeast Asian hymenosomatid fauna will prove to be more diverse than what has been reported. The ecology of the Southeast Asian species is reviewed, especially in the view that two species are completely freshwater, one of which is a troglobite. Most species are littoral or sublittoral in habit and very sensitive to human activities (e.g. pollution).     

A taxonomic reappraisal of the Daphnia hyalina complex (Crustacea: Cladocera): an experimental and ecological approach

The paper is a taxonomic study of the limnetic Daphnia populations of the English Lake District, the populations upon which the most popular taxonomic scheme is based (Johnson, 1952).
Johnson treats these populations as three varieties of the species D. hyalina, namely D. hyalina s. str., D.h. var. galeata and D.h. var. lacustris .
Careful examination of the populations of Esthwaite reveals that what has previously been regarded as a population of a single variety of D. hyalina. includes three distinct forms. Experimental work confirms that these are genetically distinct. One of these forms corresponds to D. hyalina var. galeata , whilst the other two are designated the toothed and round-headed forms.
The first part of the paper is concerned with the taxonomic status of var. galeata . Brooks (1957) and some later workers treat this as a separate species (D. galeata) on morphological grounds. This is fully supported by the present work. Differences between var. galeata and co-existing forms in incidence of sexual reproduction, in vertical distribution and in seasonal abundance and average brood-size provide further support for the separation of D. galeata.
The second part of the paper is concerned with D. hyalina s.str. which, on the basis of morphology, ecology and reproductive behaviour, is shown to be at least as distinct from other members of the complex as is D. galeata . It is argued that other forms should therefore to be removed from D. hyalina . The taxonomic status and affinities of the remaining toothed and round-headed forms are discussed.     

Phylogenetic relationships, character evolution, and taxonomic implications within the slipper lobsters (Crustacea: Decapoda: Scyllaridae)

The slipper lobsters belong to the family Scyllaridae which contains a total of 20 genera and 89 species distributed across four subfamilies (Arctidinae, Ibacinae, Scyllarinae, and Theninae). We have collected nucleotide sequence data from regions of five different genes (16S, 18S, COI, 28S, H3) to estimate phylogenetic relationships among 54 species from the Scyllaridae with a focus on the species rich subfamily Scyllarinae. We have included in our analyses at least one representative from all 20 genera in the Scyllaridae and 35 of the 52 species within the Scyllarinae. Our resulting phylogenetic estimate shows the subfamilies are monophyletic, except for Ibacinae, which has paraphyletic relationships among genera. Many of the genera within the Scyllarinae form non-monophyletic groups, while the genera from all other subfamilies form well supported clades. We discuss the implications of this history on the evolution of morphological characters and ecological transitions (nearshore vs. offshore) within the slipper lobsters. Finally, we identify, through ancestral state character reconstructions, key morphological features diagnostic of the major clades of diversity within the Scyllaridae and relate this character evolution to current taxonomy and classification.     

Coexistence of the predatory cyclopoids Acanthocyclops robustus (Sars) and Mesocyclops leuckarti (Claus) in a small eutrophic lake

The coexistence of two common species of predatory cyclopoid copepods, Acanthocyclops robustus and Mesocyclops leuckarti, in a small, eutrophic lake was studied. Both species are of similar size, inhabit the same water layers and have similar seasonal occurrence. A. robustus shows faster embryonic and postembryonic development and produces bigger clutches. Ingestion rates of A. robustus are higher than in M. leuckarti, especially with large prey types and low temperatures. Females of A. robustus are heavily preyed upon by fish. This predation pressure leads to extremely skewed sex ratios, which are unfavourable to population growth. A. robustus is therefore, on balance, favoured in productive lakes. Dominance over M. leuckarti is, however, less clear in warmer years.     

Characteristics of the reproductive cycles and development times of Copidodiaptomus numidicus (Copepoda: Calanoida) and Acanthocyclops robustus (Copepoda: Cyclopoida)

The female reproductive cycles of the calanoid copepod Copidodiaptomus numidicus and the cyclopoid Acanthocyclops robustus were characterized by periodic changes in the oviducts. Females oscillated between a gravid and a non-gravid condition, and the whole cycle was strongly dependent on temperature. In both species, the maturation of new oocytes took place when the old egg sacs were still being carried, thus ensuring a rapid clutch succession. The embryonic and post-embryonic development duration of C.numidicus and A.robustus was investigated at five and four different temperatures, respectively. Embryonic development time was related to oviductal cycle duration at each temperature to estimate the minimum amount of non-ovigerous females expected under non-limiting mate and food conditions. Copidodiaptomus numidicus females spent 35-19% of the cycle without carrying eggs at 7-20C. Acanthocyclops robustus females spent 31-33% of the cycle without carrying eggs at the same temperature interval. Both naupliar and copepodid durations were inverse functions of temperature with nauplii developing at a faster rate than copepodids. In general, A.robustus showed reproductive advantage over C.numidicus due to a faster oviductal cycle and shorter embryonic and post-embryonic development times. However, the influence of food quality may be crucial. Acanthocyclops robustus copepodid development may lengthen well beyond the corresponding development stages of C.numidicus when growing only on algae. This retardation of development affects especially the later development stages of the cyclopoid.      

A template for the future: digitizing and databasing a taxonomic illustration collection

This is the first iconographic taxonomic database intended as an everyday tool for the practising taxonomist, that allows access to the original drawings used to describe species. We demonstrate the system with water mites (Acari, Parasitengona, Hydrachnidia) but it may be used with any other plant or animal group. Query by genus or species leads to the original drawings and any additional images associated to that particular name. At present, the database includes images from more than 4,000 species (around 38,000 illustrations) and is easily expandable. Copyright does not allow the database to be used in an open WWW context, but it can be an extremely useful tool in private taxonomic applications.     

The taxonomic and ecological status of the environmentally restricted spongillid species of North America. I. Spongilla sponginosa Penney 1957

The taxonomic validity, present distribution, and specific threats to the existence of the freshwater sponge,Spongilla sponginosa Penney were investigated. This species, reported only from the type locality, Week's Pond, Sumter County, South Carolina, has apparently been extirpated due to highly acidic pH levels in the pond water. Examination of holotype materials indicate some question of the validity of S. sponginosa as a distinct species.     

Exogenous inorganic carbon sources for photosynthesis in seawater by members of the Fucales and the Laminariales (Phaeophyta): ecological and taxonomic implications

Summary Characteristics of inorganic carbon assimilation by photosynthesis in seawater were investigated in six species of the Fucales (five Fucaceae, one Cystoseiraceae) and four species of the Laminariales (three Laminariaceae, one Alariaceae) from Arbroath, Scotland. All of the algae tested could photosynthesise faster at high external pH values than the uncatalysed conversion of HCO ₃ ^- to CO₂ can occur, i.e. can use external HCO ₃ ^- . They all had detectable extracellular carbonic anhydrase activity, suggesting that HCO ₃ ^- use could involve catalysis of external CO₂ production, a view supported to some extent by experiments with an inhibitor of carbonic anhydrase. All of the algae tested had CO₂ compensation concentrations at pH 8 which were lower than would be expected from diffusive entry of CO₂ supplying RUBISCO as the initial carboxylase, consistent with the operation of energized entry of HCO ₃ ^- and / or CO₂ acting as a CO₂ concentrating mechanism. Quantitative differences among the algae examined were noted with respect to characteristics of inorganic C assimilation. The most obvious distinction was between the eulittoral Fucaceae, which are emersed for part of, or most of, the tidal cycle, and the other three families (Cystoseiraceae, Laminariaceae, Alariaceae) whose representatives are essentially continually submersed. The Fucaceae examined are able to photosynthesise at high pH values, and have lower CO₂ compensation concentrations, and lower K_1/2 values for inorganic C use in photosynthesis, at pH 8, than the other algae tested. Furthermore, the Fucaceae are essentially saturated with inorganic C for photosynthesis at the normal seawater concentration at pH 8 and 10°C. These characteristics are consistent with the dominant role of a CO₂ concentrating mechanism in CO₂ acquisition by these plants. Other species tested have characteristcs which suggest a less effective HCO ₃ ^- use and CO₂ concentrating mechanism, with the Laminariaceae being the least effective; unlike the Fucaceae, photosynthesis by these algae is not saturated with inorganic C in normal seawater. Taxonomic and ecological implications of these results are considered in relation to related data in the literature.     

Pollen morphology of Diosma and Coleonema (Rutaceae: Diosminae) and its taxonomic implications

The pollen morphology of Diosma and Coleonema of the taxonomically problematic subtribe Diosminae (Rutaceae) was investigated to determine its taxonomic relevance. Pollen of 26 of the 28 species of Diosma and of each of the eight species of Coleonema was investigated by LM, SEM and TEM. In pollen of Diosma the exine sculpturing is uniform, and only one pollen type, reticulate, could be distinguished. In contrast, exine sculpturing shows interspecific variation in Coleonema and three distinct types, striate, reticulate and perforate, could be discerned. Species groupings indicated by the pollen types suggest possible relationships between species within Coleonema and with other genera that were not previously apparent. Pollen data support macromorphological evidence that suggests the generic re-classification of the Diosminae.     

基于系统发生探讨绿带翠凤蝶和西番翠凤蝶的分类地位(英文)

绿带翠凤蝶和西番翠凤蝶的分类问题存在一定的争议。应用分子系统学方法对这一问题进行了研究。对6个不同地区的24个绿带翠凤蝶、2个地区的16个西番翠凤蝶个体的COI(579bp)和COII(655bp)基因测序,绿带翠凤蝶与西番翠凤蝶的遗传距离为0至0.6%,共获得了15个单倍型。结果显示这些单倍型不能形成各自独立的单系群,因此认为绿带翠凤蝶和西番翠凤蝶为近期分化的两个种。     

Rotifer communities of floodplain lakes of the Brahmaputra basin of lower Assam (N.E. India): biodiversity, distribution and ecology

The rotifer communities of 15 acidic – alkaline and soft – marginally hard water floodplain lakes of the lower Assam valley of the Brahmaputra river basin, characterized by low ionic concentrations, reveal 164 species (178 taxa) belonging to 39 genera and 20 families and represent the richest biodiversity known to date in these ecotones of the Indian subcontinent. Nine species are new to the Indian Rotifera. Cosmopolitan (59.7%) > pantropical (15.2%) > cosmotropical (12.2%) species dominate the taxocoenosis. Biogeographically interesting elements constitute a notable component (13.4%); important members of this category include six Oriental, two Australasian and seven Palaeotropical species. The examined fauna depicts a tropical character with predominance of Lecanespp. (28.0%). Littoral or periphytic rotifers (76.2%) dominate the planktonic species. Rotifers comprise a dominant qualitative (67–103, 79.1±11.0 species) and an important quantitative (mean: 41.1–65.9%) component of zooplankton in all floodplain lakes, register a moderate diversity (mean: 2.036–2.642), low dominance (mean: 0.019–0.216) and high evenness (mean: 0.840–0.893). The examined material indicates several interesting acidophilous elements. Richness depicts significant inverse correlation with pH. Water temperature, conductivity, dissolved oxygen and alkalinity record significant direct relationships with the rotifer abundance. Diversity is influenced by abundance and is also directly correlated with water temperature and conductivity. Canonical analysis shows a notable cumulative impact of six abiotic factors on richness, density and diversity.     

Three new Verrucidae (Crustacea: Cirripedia) from the Upper Eocene of the Euganean Hills (Northeast Italy)

Marls with pillow lavas of Late Eocene age from Castelnuovo in the Euganean Hills (Padua, NE Italy) have yielded three new verrucid cirripede species, Verruca veneta nov. sp., Costatoverruca? seguenzai nov. sp., and Metaverruca euganea nov. sp. The stratigraphic distribution of these taxa is discussed in light of previous verrucid records and their geologic context is established. They represent the oldest known verrucids from Italy.     

Some notes on the ecology of a GermanBranchipus schaefferi population (Crustacea: Anostraca)

Habitat preference, seasonal occurrence, starvation resistance, hatching eggs ofBranchipus schaefferi, and effects of predation onB. schaefferi were studied.Branchipus was only present in turbid, unvegetated ponds and absent in ponds which contain higher aquatic vegetation and theSpirogyra sp. The first individuals ofB. schaefferi appeared in April when water temperature was 10 °C and the last adults in November at a water temperature of 3.5 °C. Up to 6 reproducing generations were observed during this period. Abundance ofB. schaefferi was higher in temporary ponds than in permanent ponds. Sex ratio was close to unity for most of the year. Body size ofB. schaefferi males and females was significantly positively correlated with pond volume. Without foodB. schaefferi could survive for 1.5 to 2 days at 20 °C and 4 to 5 days at 10 °C. Hatching success of eggs decreased when eggs were dried for 7 months. Freezing of eggs had no effect on hatching success. From] the predators tested,Chaoborus sp. larvae clearly selected smallB. schaefferi; one consumed approximately 6Branchipus d–1 at a density of 6 to 12 prey 1–1. The other predators, dragonfly larvae, and larvae and adults ofTriturus alpestris selected alternative prey types, for exampleTubifex sp. and ostracods.     

Behavioural and ecological investigations of the crabOcypode ceratophthalmus (Crustacea: Ocypodidae)

Observations conducted at different places along the Moçambique coast indicate that the behaviour of Ocypode ceratophthalmus is extremely plastic, permitting a high degree of adaptation to the often vastly different shores on which they are found. When the crabs are nocturnal and when, as is usual, the burrows are intertidally placed, the greater part of the crab's life is spent beneath the sand and the periods of activity are much influenced by the tidal cycles. Apart from feeding on items of prey conveyed into the burrows and stridulating when disturbed there is no evidence that they are anything but inactive when underground. On emergence from the sand the sole major activities observed were searching for food and the digging and clearing of burrows. They are very aggressive and although cannibalism is common, conflicts between equal sized crabs are generally ritualized. Social behaviour appears limited and, except for protest stridulation and ritualized posturing during intraspecific encounters, none was observed.     

Pollen morphology and its taxonomic significance of the monotropoideae (Ericaceae)

A palynological survey, including LM, SEM and TEM is presented for eight genera, nine species and 76 samples of the Monotropoideae which is composed of 10 genera and 13 species. On the basis of the aperture number and shape, the following six pollen types are recognized: 1) 3-colp(oroid) ate—Allotropa, 2) 2-colpor(oid)ate—Monotropsis andHemitomes, 3) 4-colpor(oid)ate—Pterospora, Sarcodes andPleuricospora, 4) 2- and 3-colpor(oid)ate—Monotropa hypopitys, 5) 3-colporate and-porate —Monotropa uniflora, 6) 3- to 4- porate—Monotropastrum humile. Relationships among taxa within the Monotropoideae are illustrated on the palynological characters including the aperture type, exine sculpture and structure. Both pollen grains with two and four apertures have evolved independently from pollen grains with three apertures, according to the infraspecific variation of aperture numbers and the usual occurrence of three-aperturate pollen grains in the Ericaceae. 3-colp(oroid)ate pollen ofAllotropa is the most primitive and occupies an isolated position in the subfamily, on the other hand 3- to 4-porate pollen ofMonotropastrum humile is most advanced in the subfamily, probably even in the Ericaceae. A reduced sexine inMonotropastrum humile appears to be a specialized pollen character. Infraspecific geographical difference in palynological characters is revealed in two species ofMonotropa for the first time.M. hypopitys is basically characterized by pollen grains with two apertures in the New World vs. three apertures in the Old World.M. uniflora is basically characterized by 3-porate pollen in the New World vs. 3-colporate in the Old World. In both species pollen grains with more primitive characters usually occur in the Old World.     

Esteval phenology of an Acanthocyclops (Crustacea,Copepoda) in a Colorado tarn with remarks on the vernalis-robustus complex

Weekly mean lenghts of adult female Acanthocyclops robustus ranged between 1.14 and 1.41 mm in a Colorado alpine lake during the summer of 1966. The smallest animals occurred in late September and the largest in mid-August, corresponding to development in warm and cool water, respectively. The males also declined in mean length during the course of the summer and were about 70% of the length of the females on any date. About 75% of the females possessed a 3.4.4.4 spine formula; 8%, 2.3.3.3 and 17% an anomalous formula. Eight-one percent of the males had a 3.4.4.4 formula; 7%, 2.3.3.3 and 12% were anomalous. Morphological variation, and breeding experiments performed by Price (1958) suggest that A. robustus and A. vernalis as defined by Kiefer (1976) are likely species complexes, rather than just two species.