Feeding habits of two sympatric loliginid squids,Uroteuthis (Photololigo) chinensis (Gray, 1849) and Uroteuthis (Photololigo) duvaucelii (d’Orbigny, 1835), in the lower part of the South China Sea

The feeding habits of two sympatric squid species, Uroteuthis (Photololigo) chinensis and Uroteuthis (Photololigo) duvaucelii from the southwestern Gulf of Thailand were studied. They fed on low numbers of food types (AF) and had a low diet breadth; 1.18 and 0.01 for U. (P.) chinensis and 1.49 and 0.05 for U. (P.) duvaucelii, respectively. Three major prey types (fishes, crustaceans and molluscs) were always detected and cannibalism was observed. Fish was the greatest contributor to the diet of both species, contributing 89.5% for U. (P.) chinensis and 69.9% for U. (P.) duvaucelii. Fish size significantly affected fullness index (FL) and AF for U. (P.) chinensis (P?<?0.001) and U. (P.) duvaucelii (P?<?0.001). Depth affected the FL of U. (P.) chinensis (P?<?0.001) but not of U. (P.) duvaucelii (P?>?0.05). Maturity stages of both male and female U. (P.) chinensis influenced FL (male: P?<?0.001; female: P?<?0.05) and AF (male: P?<?0.05; female: P?<?0.01). The FL of squid from cast nets was higher than those from trawls. The multivariate results showed dietary grouping between size classes of both species.     

Systematics of Alloteuthis (Cephalopoda:Loliginidae) based on molecular and morphometric data

Alloteuthis is a group of small, slender loliginid squids of minor fisheries importance. There are three nominal Alloteuthis species—A. media (Linnaeus), A. subulata (Lamarck) and A. africana Adam. Two of these species (A. media and A. subulata) have largely overlapping ranges in the Mediterranean and northeastern Atlantic, while A. africana is found along the west coast of Africa. Despite the low level of species diversity, Alloteuthis taxonomy and systematics are confused, and assignment of specimens to species can be difficult. To clarify Alloteuthis systematics, we gathered morphometric data and DNA sequence data from two mitochondrial loci and a nuclear locus from Alloteuthis specimens collected from several localities. Analyses of the morphometric data suggest that head width is the main variable allowing separation of A. africana from the other two species, and central club sucker size separates A. media from A. subulata. One easily diagnosable character often used to distinguish Alloteuthis species—relative fin length—appears to be of little taxonomic value. Only three specimens assignable to A. subulata both morphologically and genetically were found, all from the Adriatic; possible reasons for this apparent rarity are discussed. Gene tree parsimony and coalescent-based methods were used to estimate species relationships from the molecular data, and both supported a sister-species relationship between A. media and A. subulata. Analyses of molecular variation (AMOVA's) revealed significant genetic differentiation between Atlantic and Mediterranean A. media. This study highlights the importance of 1) sampling multiple individuals, locations and loci for species-level phylogenetic studies, 2) using morphometric analyses to reveal taxonomically meaningful morphological characters and 3) accounting for the stochastic nature of the coalescent process when estimating species phylogenies for closely related taxa.     

Population genetic differentiation of Schisandra chinensis and Schisandra sphenanthera as revealed by ISSR analysis

Schisandra chinensis (Turcz.) Baill. and Schisandra sphenanthera Rehd. et Wils. are well-known Chinese medicinal plants. The population genetic variation of the two species was studied using inter simple sequence repeat (ISSR) molecular markers. High levels of genetic diversity are revealed in both S. chinensis (P = 88.36%, h = 0.2894, I = 0.4396) and S. sphenanthera (P = 84.09%, H = 0.2782, I = 0.4280). However, the population genetic differentiation is significantly different between the two species. The S. sphenanthera harbors as high as 27% of the genetic variation among populations but 73% within populations, whereas in S. chinensis 17% of the genetic variation occurs among populations and 83% within populations. Both significant (P < 0.05) heterozygosity excess and shifted mode of allele frequency distribution are detected in four out of six populations of S. chinensis and one out of five populations of S. sphenanthera, suggesting the occurrence of recent population bottlenecks in the two species. The different patterns of genetic variation in S. chinensis and S. sphenanthera are discussed in relation to their differences in pollination mechanism, geographic distribution and historical events, and the level of gene flow and genetic drift.     

Phylogeny and historical biogeography of the loliginid squids (Mollusca: cephalopoda) based on mitochondrial DNA sequence data

The cephalopod taxon Loliginidae (Cephalopoda: Myopsida) is a species-rich group of tropical and temperate shallow-water squids, many of which are commercial fisheries objects and neurophysiological research organisms. The worldwide distribution of these squids could make Loliginidae a useful case study in shallow-water marine biogeography, but the phylogeny of the group is unknown. To clarify loliginid phylogeny, regions of two mitochondrial genes (the 16S rRNA and the cytochrome c oxidase subunit I genes) were sequenced for members of 19 loliginid species and several outgroups. Maximum-parsimony and maximum-likelihood analyses were performed on a combined data set, as well as on each data set individually. Analyses of the combined data support loliginid monophyly and reveal four clades-one consisting primarily of species in American waters from two genera, one composed of 3 east Atlantic species, one consisting of the bioluminescent loliginids (Uroteuthis sensu Vecchione et al., 1998) plus Loliolus japonica, and one represented by a Loligo (Alloteuthis) subulata-Lolliguncula mercatoris pair. The likelihood of the unconstrained maximum-likelihood tree is not significantly better than the likelihoods of the best trees constrained to Sepioteuthis monophyly or Uroteuthis monophyly, but there is significant support for Lolliguncula polyphyly. Tests of alternative hypotheses of loliginid cladogenesis suggest that cladogenesis within Loliginidae is correlated with the widening of the Atlantic and the closure of the Tethys Sea, although dispersal from the Indo-West Pacific is a reasonable explanation for the origin of the clade of American loliginines.     

Isolated and combined impacts of blue mussels (Mytilus edulis) and barnacles (Balanus improvisus) on structure and diversity of a fouling community

Effects of two presumably dominant competitors, the blue mussel Mytilus edulis and the barnacle Balanus improvisus on recruitment, population dynamics and community structure on hard substrata were experimentally investigated in the subtidal Kiel Fjord, Western Baltic. The hypothesis that blue mussels and/or barnacles are local dominants and strongly influence succession and community structure was tested by monitoring succession in the presence and absence of simulated predation on either or both species. Manipulations included blue mussel removal, barnacle removal, combined blue mussel and barnacle removal, as well as a control treatment for natural (non-manipulated) succession. In the second part of the experiment, recovery from the treatments was monitored over 1 year.During the manipulative phase of the experiment, blue mussels had a negative effect on recruitment of species, whereas barnacles had no significant effect. Even so, a negative synergistic effect of blue mussels and barnacles was detected. Calculation of species richness and diversity H′ (Shannon Index) showed a negative synergistic effect of blue mussels and barnacles on community structure. Additionally, diversity H′ was negatively affected by the dominant competitor M. edulis. These effects were also detectable in the ANOSIM-Analysis. The non-manipulative phase of the experiment brought about a drastic loss of diversity and species richness. Blue mussels dominated all four communities. Barnacles were the only other species still being able to coexist with mussels. Effects of simulated predation disappeared fast.Thus, in the absence of predation on blue mussels, M. edulis within a few months dominates available space, and diversity of the benthic community is low. In contrast, when mussel dominance is controlled by specific predators, more species may persist and diversity remains high.     

Pollen morphology of Chinese Curcuma L. and Boesenbergia Kuntz (Zingiberaceae): Taxonomic implications

In order to find new non-molecular evidence to support the phylogenetic and taxonomic position, pollen grains of 20 populations of 16 species of Chinese Curcuma L. and Boesenbergia Kuntz (Zingiberaceae) were investigated under SEM and TEM. The pollen grains are spherical and ovoid, nonaperturate. The pollen wall is composed of a very thin exine and a thick intine. The exine is psilate or echinate. The intine consists of two layers, i.e., a thick, channeled layer (exintine) and an inner homogenous layer (endintine). The results reveal morphological congruence between the pollen grains of species of Curcuma, which according to DNA sequence data appears to be a polyphyletic genus. However the uniform pollen morphology in Curcuma provides no evidence to divide this genus into separate taxonomic entities. Our results on pollen morphology also do not provide any additional evidence to either unite or segregate Boesenbergia albomaculata and Curcumorpha longiflora in the same genus and demonstrate that more taxonomic data on the genus Boesenbergia and its relatives are needed before a final decision can be made.     

Chemistry of Chinese yew, Taxus chinensis var. mairei

Taxus chinensis var. mairei (Lemée et Lévl) Cheng et L.K. Fu is an evergreen tall tree ubiquitous to the southeastern region in China. The first chemical study on this species was published in 1987. Since then about 163 compounds including taxoids and non-taxane compounds were isolated from seeds, root, bark and leaves of this species. This review summarized the chemical investigation on T. chinensis var. mairei (Lemée et Lévl) Cheng et L.K. Fu in the past 20 years. T. chinensis var. mairei (Lemée et Lévl) Cheng et L.K. Fu was assigned as a variation of T. chinensis (Pilger) Rehd. in Flora of China. However, present chemotaxonomic data would suggest that these two plants might belong to two different chemotypes; further genetic investigation and comprehensive chemical studies on them are warranted to address this issue.     

不同群落中米氏冰草和羊草的年龄结构动态

米氏冰草和羊草都是根茎型禾草,是典型的无性系植物。采取单位面积挖掘取样法,对呼伦贝尔沙地植被次生演替过程中的米氏冰草和羊草种群分株年龄结构进行调查。结果表明,在单生和混合群落中,米氏冰草分株分别由3和4个年龄级组成,羊草均由2个年龄级组成;米氏冰草分株数量和生物量年龄结构变化基本一致,即随着生长年限的延长,呈减少低龄级和增加高龄级比例的趋势,使单生群落中始终为增长型,但接近于稳定型,混生群落中由增长型变为稳定型。羊草分株数量和生物量年龄结构在连续2a均为明显的增长型。羊草各龄级平均单株生产力均高于米氏冰草,平均是米氏冰草的5.2倍。米氏冰草和羊草种群分株年龄结构的变化,蕴含着米氏冰草种群的优势地位将被羊草种群取代的趋势。     

Assessing the potential benthic-pelagic coupling in episodic blue mussel (Mytilus edulis) settlement events within eelgrass (Zostera marina) communities

Coastal marine seagrass ecosystems are important nursery grounds for commercially and recreationally important species, and they serve as key settlement and recruitment sites for other species. We investigated several years (2001-2003) where episodic settlement events of blue mussels (Mytilus edulis) occurred in Barnegat Bay, NJ, USA. Population assessment indicated that blue mussels settled in eelgrass beds (Zostera marina) in late spring with peak densities exceeding 170,000 m⁻². Based on calculated filtration rates of M. edulis, we determined that for at least 53 days in 2001, the density and size distribution of M. edulis were sufficient to filter the water column volume in excess of twice a day, with maximum calculated filtration rates exceeding 8 m³ water m⁻² day⁻¹. While the settlement event in 2001 was very localized, in 2003, the settlement event was considerably more widespread throughout the bay, with maximum settling densities exceeding 175,000 individuals m⁻². Associated with these high densities, maximum calculated filtration rates exceeded 15 m³ water m⁻² day⁻¹. This filtration potential may have impeded the localized development of a brown-tide (Aureococcus anophagefferens) bloom in 2001, which occurred in other regions of the bay, but the widespread settlement event seen in 2003 may have impeded the development of any brown-tide blooms in Barnegat Bay during that summer. The decline in mussel densities throughout the summer may be a result of elevated water temperatures in this back bay, but at one site, the high settlement of M. edulis was followed by a substantial migration (>40 individuals m⁻²) of small sea stars (Asterias forbesii). In 2001, A. forbesii was a significant factor in reducing M. edulis density by the end of the summer at the Barnegat Inlet site and a community level assessment showed significant positive correlations between mussel aggregations and sea star densities (r=0.68-0.73, P<0.001). At this same site in 2003, the sea stars were again present in high densities (26 m⁻²) and were a potential mechanism for mussel decline. In other regions of the bay, sea star densities are very low, but numerous other predatory species exist, including blue crabs (Callinectes sapidus), green crabs (Carcinus maenus), spider crabs (Libinia spp.), and several Xanthid crabs. Given the high mussel densities seen in this study and the considerable predation by sea stars and other benthic predators, the benthic-pelagic coupling which these mussels provide in this system contributes to the high secondary production in these grass beds.     

Experimental test of biodeposition and ammonium excretion from blue mussels (Mytilus edulis) on eelgrass (Zostera marina) performance

Blue mussels and eelgrass have been found to coexist in many locations. However, knowledge of the interactions between these species is limited. Two experiments were conducted in the laboratory, a “Deposit” and an “Epiphyte” experiment. The Deposit experiment examined possible effects of increasing load of blue mussel (Mytilus edulis) biodeposits on sediment biogeochemistry and eelgrass (Zostera marina) performance. Z. marina mesocosms received normal or high loads of mussel biodeposits (Normal and High), while no biodeposits were added to the Control. High dosage had overall negative effects on Z. marina, which was reflected as lower leaf numbers and biomass and accumulation of elemental sulphur in rhizomes. The sediment biogeochemical conditions were altered, as the mussel biodeposits enhanced sulphate reduction rates and increased sulphide concentrations in the porewater, which may result in sulphide invasion and reduced growth of Z. marina.In the Epiphyte experiment effects of mussel excretion, with particular emphasis on ammonium, on the growth of Z. marina and their epiphytes were examined. A thick cover of epiphytes developed on Z. marina growing together with M. edulis, and the relative growth rate was reduced with 20% compared to plants from control without mussels. Overall the experiments showed negative effects on Z. marina growing together with M. edulis, thereby supporting a preceding field study by Vinther et al. [Vinther, H.F., Laursen, J.S., Holmer, M. 2008. Negative effects of blue mussel (Mytilus edulis) presence in eelgrass (Zostera marina) beds in Flensborg fjord, Denmark. Est. Coast Shelf. Sci. 77, 91-103.].     

Phylogenetic analysis of nuclear and mitochondrial DNA reveals a complex of cryptic species in Crassicutis cichlasomae (Digenea: Apocreadiidae), a parasite of Middle-American cichlids

We obtained nuclear ITS-1 and mitochondrial cox1 sequences from 225 Crassicutis cichlasomae adults collected in 12 species of cichlids from 32 localities to prospect for the presence of cryptic species. This trematode is commonly found in species of cichlids over a wide geographic range in Middle-America. Population-level phylogenetic analyses of ITS-1 and cox1, assessments of genetic and haplotype diversity, and morphological observations revealed that C. cichlasomae represents a complex of seven cryptic species for which no morphological diagnostic characters have been discovered thus far. Bayesian and Maximum Likelihood analyses of concatenated datasets (906 bp) recovered eight lineages of C. cichlasomae, all with high posterior probabilities and bootstrap branch support. Values of genetic divergence between clades ranged from 1.0% to 5.2% for ITS-1, and from 7.2% to 30.0% for cox1. Morphological study of more than 300 individuals did not reveal structural diagnostic traits for the species defined using molecular evidence. These observations indicate that some traditional morphological characters (e.g., testes position) have substantial intra-specific variation, and should be used with caution when classifying C. cichlasomae and their sister taxa. Additionally, phylogenetic analyses did not reveal a strict correlation between these cryptic species and their host species or geographic distribution, however it appears that genetic distinctiveness of these cryptic species was influenced by the diversification and biogeographical history of Middle-American cichlids.     

Molecular differentiation and phylogenetic relationships of three Angiostrongylus species and Angiostrongylus cantonensis geographical isolates based on a 66-kDa protein gene of A. cantonensis (Nematoda: Angiostrongylidae)

The phylogenetic relationships and molecular differentiation of three species of angiostrongylid nematodes (Angiostrongylus cantonensis, Angiostrongylus costaricensis and Angiostrongylus malaysiensis) were studied using the AC primers for a 66-kDa protein gene of A. cantonensis. The AC primers successfully amplified the genomic DNA of these angiostrongylid nematodes. No amplification was detected for the DNA of Ascaris lumbricoides, Ascaris suum, Anisakis simplex, Gnathostoma spinigerum, Toxocara canis, and Trichinella spiralis. The maximum-parsimony (MP) consensus tree and the maximum-likelihood (ML) tree both showed that the Angiostrongylus taxa could be divided into two major clades - Clade 1 (A. costaricensis) and Clade 2 (A. cantonensis and A. malaysiensis) with a full support bootstrap value. A. costaricensis is the most distant taxon. A. cantonensis is a sister group to A. malaysiensis; these two taxa (species) are clearly separated. There is no clear distinction between the A. cantonensis samples from four different geographical localities (Thailand, China, Japan and Hawaii); only some of the samples are grouped ranging from no support or low support to moderate support of bootstrap values. The published nucleotide sequences of A. cantonensis adult-specific native 66 kDa protein mRNA, clone L5-400 from Taiwan (U17585) appear to be very distant from the A. cantonensis samples from Thailand, China, Japan and Hawaii, with the uncorrected p-distance values ranging from 26.87% to 29.92%.     

毛竹浸提液对苦槠幼苗生长的化感效应

为探讨毛竹(Phyllostachys edulis)扩张过程中潜在的化感作用,选择苦槠(Castanopsis sclerophylla(Lindl)Schott)为研究对象。采用水浸提的方法,用毛竹茎叶、枯落物和土壤3部分浸提液浇灌苦槠幼苗,以蒸馏水处理作为对照,对比分析质量浓度分别为0.1、0.05、0.02 g/mL的3个浓度梯度浸提液处理下苦槠幼苗生长指标及各项光合生理指标的差异。结果表明,毛竹浸提液对苦槠幼苗苗高、地径和叶绿素相对含量的影响大体上呈现高浓度抑制低浓度促进的双重浓度效应。不同来源毛竹浸提液的化感效应不尽相同,土壤浸提液对苦槠幼苗生长和光合生理均呈现抑制作用,而茎叶、枯落物浸提液低浓度时为促进作用。毛竹潜在的化感作用,在其扩张过程中可能会干扰森林主要树种更新,从而对森林群落产生威胁。     

On the status of Isolophodon Roth, 1903 (Mammalia,Astrapotheria) and other little-known Paleogene astrapotheres from central Patagonia

Most of the 16 currently recognized astrapothere genera are well known through numerous specimens preserving at least almost complete dentition. One of the exceptions is the enigmatic genus Isolophodon Roth, 1903, based on very scant and fragmentary materials from Paleogene levels of central Patagonia. This taxon was ruled out from almost all taxonomic lists, although its validity has not been discussed by subsequent authors. We herein re-describe and discuss the taxonomic status of the species of Isolophodon. The type species, I. cingulosus Roth, 1903, is characterized by having lower cheek teeth with a much reduced hypoflexid, resembling derived uruguaytheriines, but lower-crowned and with three lower premolars, as in the species of Astraponotus Ameghino, 1901. This is the only astrapothere nominal species attributable to the Tinguirirican South American Land Mammal Age (SALMA, Early Oligocene). Isolophodon aplanatus Roth, 1903 (Casamayoran and Mustersan SALMAs, middle Late Eocene) has proportionally more elongated lower molars and a less developed paraflexid than the type species. Isolophodon would represent an early diverging lineage of astrapotheriids, in which some dental features evolved convergently with the more derived uruguaytheriines. Additionally, we describe other fragmentary but very significant specimens from Paleogene localities in central Patagonia (Argentina) attributable to the following taxa: cf. Scaglia kraglievichorum (Barrancan? subage), based on a partial upper molar nearly 60% larger than the type of Scaglia kraglievichorum Simpson, 1957; Astrapotheriidae gen. et sp. 1 (Barrancan? Subage, Middle Eocene), based on an isolated upper molar larger than any other Eocene astrapothere; Astrapotheriidae gen. et sp. 2, based on five isolated upper cheek teeth from “La Cantera” (Gran Barranca, Early Oligocene), characterized by a large, isolated hypocone and accessory cusps on P3-P4. These taxa enlarge the known diversity of Paleogene astrapotheres and document novel evolutionary patterns for these mammals.     

Are the microcyclic rust species Puccinia melampodii and Puccinia xanthii conspecific?

The taxonomic relationship between two microcyclic rust species, Puccinia melampodii and Puccinia xanthii, recorded from a number of Asteraceae hosts, was explored by comparing teliospore morphology, host specificity and sequence data. Teliospore morphology varied between and within individual rust accessions but, in general, teliospores of P. xanthii were larger than those of P. melampodii. Field observations and cross-inoculation greenhouse studies showed that P. melampodii accessions were highly specific to their original host species and unable to establish compatible interactions with related Asteraceae species. Though small amounts of genetic variation were detected between P. melampodii and P. xanthii accessions, the ITS and TEF phylogenetic analyses comprising several other rust species grouped these accessions within a well supported clade. Our data indicate that despite differences between P. xanthii and P. melampodii accessions these rusts cannot readily be separated at the species level, supporting earlier taxonomic conclusions and the recent proposal to group them into a morphospecies. Based on host-specificity data, the name Puccinia xanthii var. parthenii-hysterophorae is proposed to accommodate all Mesoamerican records of P. melampodii associated with the host Parthenium hysterophorus.     

Identification of Mediterranean Diplodus spp. and Dentex dentex (Sparidae) by means of DNA Inter-Simple Sequence Repeat (ISSR) markers

The aim of this paper was to test the effectiveness of Inter-Simple Sequence Repeat (ISSR) technique in detecting specific molecular markers to genetically discriminate some species of teleost fish. As model species, we used four Mediterranean sea bream species (i.e. Diplodus annularis, D. puntazzo, D. sargus sargus, and D. vulgaris), and the common Mediterranean dentex Dentex dentex. Furthermore, the occurrence in our samples of two partially albino sparids (suspected, on a morphological basis, to probably belong to D. sargus sargus and to D. dentex, respectively) allowed ISSRs to be tested on doubtful specimens. Eight ISSR primers produced 95 out of 97 scorable polymorphic loci with a large number (63) of species-private bands. Maximum parsimony analysis, ΔK statistics, and assignment test were consistent in separating the five species and solving the taxonomic position of specimens of dubious attribution. The results obtained evidence the usefulness of ISSR markers in specimen and species identification, particularly when the morphological traits of fish make the classification problematic.     

Molecular phylogenetic analysis of white prawns species and the existence of two clades in Penaeus merguiensis

Closely related species, Penaeus merguiensis and Penaeus silasi from Thai waters, were genetically examined using variation observed in 558 base pairs (bp) of sequence from cytochrome oxidase subunit I (COI) gene of mtDNA. The sequence divergences of COI between P. merguiensis and other Penaeus species were 5.76-6.15% (P. silasi), 13.17-13.97% (Penaeus indicus), 16.43% (Penaeus vannamei), 16.63% (Penaeus monodon), and 18.37% (Penaeus japonicus). From the alignment reported that there were four clades on phylogenetic tree, the distinction of the two monophyletic clades was referred as P. merguiensis, one monophyletic clade within P. silasi and P. indicus. These results point toward the possibility of P. merguiensis being a complex of two cryptic species or a single species with strong phylogeographic subdivision.