Population biology of bryozoans: correlates of sessile,colonial life histories in freshwater habitats

Bryozoans are common, often abundant, sessile, colonial invertebrates of freshwaters. By reviewing what is known of their general ecology and considering in further detail the population biology of specific groups, we provide evidence that 1) populations are locally ephemeral and regional persistence is attained via a dynamic equilibrium between dispersal and colonization, and 2) sex may often be infrequent and a high degree of clonality obtains at both local and regional scales. On the basis of these characteristics we discuss how the group offers exceptional opportunities for investigating a number of fundamentally important ecological and evolutionary questions.The highly curious modification of the Molluscan type which the Polyzoa [=Bryozoa] present... the great beauty of their forms, and the facility with which they can in general be observed in a living state, cannot but render them special favorites for every lover of Nature; and for the more profound student must confer on them a peculiar significance, and invest their study with a scientific interest which is scarcely surpassed by that of any other group of animals.... (Allman 1856)     

Allozyme electrophoresis demonstrates the presence of a species boundary in freshwater crabs (Decapoda: Potamonautidae)

Potamonautes granularis, P. perlatus and P. sidneyi are morphologically similar species of freshwater crab occurring in the middle to lower reaches of rivers. Potamonautes perlatus and P. sidneyi are known to exhibit clinal morphological differentiation between two distinct morphotypes and their specific status has remained obscured. This study investigates the species boundaries between these three species, as well as genetic differentiation and gene flow between populations within each species, using allozyme electrophoresis. Twenty-five populations (including two P. granularis, 10 P. perlatus and 13 P. sidneyi populations) were utilized, collected along a transect of 2300 km. Individuals were screened for 11 presumptive loci, using a horizontal starch-gel electrophoresis protocol. Mean genetic identities obtained in pair-wise comparisons of populations of different species (I =0.748-0.846) were typical of interspecific comparisons. Diffuse species boundaries (over which gene flow and hybridization may be possible) were observed between P. granularis and P. perlatus, and between P. perlatus and P. sidneyi. A fixed allele difference at the ME locus distinguished P. granularis and P. sidneyi. Hierarchical F -statistics revealed significant genetic sub-structuring between populations within each species and within the entire sample, illustrating low-levels of gene flow. Although some regional groupings were evident from the genetic data, no distinct distance-related patterns, or patterns of clinal variation could be observed. Patterns of genetic differentiation resemble a patchwork that is probably the product of mutations, genetic drift, balanced by low levels of gene flow, and natural selection. The extensive morphological variation must now be seen against the backdrop of three genetically defined species.     

A new species of Hyalella from Colombia,and the redescription of H. meinerti Stebbing, 1899 from Venezuela (Crustacea: Amphipoda)

The new species H. quindioensis is described from Colombia. This species is close to H. paramoensis Andres, 1988 also in Colombia. Hyalella meinerti Stebbing, 1899 is figured and redescribed. The type locality for this species is Venezuela. However, it has a wide distribution including Colombia, Peru, Ecuador and Brazil.     

徐州淡水枝角类的调查

在徐州市郊调查,共获淡水枝角类31种,其中有6种为江苏省新记录。对这些枝角类进行分析,可以认为,徐州的淡水枝角类的区系组成,具有南方种与北方种过渡地区的特点,但又偏重于南方种。     

Rediscovery of Gastrostyla setifera (Engelmann, 1862) Kent, 1882: morphology and divisional morphogenesis (Ciliophora,Hypotrichida)

The morphology and morphogenesis of the poorly known hypotrichous ciliate Gastrostyla setifera, isolated from a freshwater pond near Harbin, China, are described from both living and protargol silver-impregnated specimens. The Harbin population of this species is characterized thus: medium-sized freshwater Gastrostyla, 150-205 × 70-95 μm in vivo, ellipsoid in shape but somewhat narrowed posteriorly. Contractile vacuole located in left half of mid-body region. On average 48-56 (mean 52) adoral membranelles; 10 frontal and 9-11 ventral cirri; 23-26 left and 30-34 right marginal cirri; usually with four complete dorsal kineties and two dorsomarginal kineties; three caudal cirri present at posterior margin; invariably two macronuclear nodules and two micronuclei. Its morphogenesis reveals the following characteristics: (1) adoral zone of membranelles (AZM) in the opisthe arises from the new oral primordium while the proter inherits the entire parental structure; (2) 10 frontal, 9-11 ventral and five transverse cirri are derived from five frontoventral transverse cirral anlagen together with the undulating membrane anlage; (3) left and right marginal cirri are derived from new anlagen which originate within the old marginal rows; (4) the generation of the dorsal kineties is of the 'two-group-mode'; three left primary dorsal anlagen and two dorsomarginal anlagen appear as two groups in both dividers from which all dorsal kineties are derived (the fourth kinety is formed due to the fragmentation of the third anlage); (5) one caudal cirrus is formed at the ends of each of the first, second and fourth dorsal anlagen.     

Two new Mastigodiaptomus (Copepoda,Diaptomidae) from southeastern Mexico,with a key for the identification of the known species of the genus

Two new species of the freshwater planktonic copepod genusMastigodiaptomus—M. maya and M. reidae—are described from material collected in southeastern Mexico. This neotropical genus is known to be distributed mainly in the southern part of the United States, Mexico and Central America, and now embraces eight species. Of these, six occur in Mexico. Both new species seem to be closely related to M. texensis and M. albuquerquensis. It is probable that this group of Mexican species represents a northwards radiation from the Proto-Antilles-Central America region into the continent, eventually reaching North America. A key for the identification of the known species of the genus is provided.     

In vivo effects of epinephrine in a freshwater fish

Summary In vivo effects of epinephrine were investigated in a freshwater teleost,Barbus conchonius Hamilton. Fish given 2 mg/kg epinephrine in a single i.m. dose showed significant hypocholesterolemia and elevated, liver and kidney cholesterol levels 1–8 h postinjection. Plasma amino nitrogen evinced a transient yet significant fall at 2 h followed by a significant increase after 24 h. A marked reduction occurred in the plasma FFA and organic PO₄ levels after 1–8 h. The results offer little evidence for a lipolytic effect of epinephrine in this species, and the changes in metabolite levels are attributable, in part, to the catecholamineinduced modification of insulin secretion.N.K. thanks the U.G.C. for the award of a research fellowship.     

中水道的开发利用

本文提出的中水道系统,将-部份生活废水进行深化处理后,作为非饮用水得到重复利用,以期部份解决日益严重的淡水资源短缺问题。     

Freshwater ostracods (Crustacea) from Tiantong National Forest Park and Dongqian Lake,eastern China,with descriptions of two new species

In this study, 192 samples were collected and analyzed from diverse water bodies in the Tiantong National Forest Park and Dongqian lake in Zhejiang Province, China. Twenty living ostracod species were identified, belonging to four families, eight subfamilies and 15 genera. Among them, two species are new, belonging to the genera Ilyocypris and Schellencandona; seven species, including Dolerocypris ikeyai Smith and Kamiya, 2006, Pseudocandona abei Smith and Janz, 2008, Stenocypris hirutai Smith and Kamiya, 2006, S. viridis Okubo, 1990, Tanycypris alfonsi Nagler et al., 2014, T. centa Chang et al., 2012 and Vestalenula cornelia Smith et al., 2006, are new records for China; nine species are reported only from Asia: Candonopsis (Candonopsis) transgrediens Brehm, 1923, Chrissia dongqianhuensis Kong et al., 2014, Dolerocypris ikeyai Smith and Kamiya, 2006, Ilyocypris dui n. sp., Pseudocandona abei Smith and Janz, 2008, Schellencandona dui n. sp., Stenocypris hirutai Smith and Kamiya, 2006, S. viridis Okubo, 1990 and Vestalenula cornelia Smith et al., 2006. Of the above species, the two new species, Schellencandona dui n. sp. and Ilyocypris dui n. sp., are described and illustrated, and Stenocypris viridis is re-described.

www.zoobank.org/urn:lsid:zoobank.org:pub:2D679051-CBA2-4B09-BCF0-E0152EBC2694     

福建淡水轮虫

本文记载了福建省的淡水轮虫151种,其中新种1个,国內新记录2个。文章还对福建淡水轮虫的种类分布作了概述。