Summary 1The diversity and abundance of viable diaspores trapped at the downstream end of a 15-km lowland stream were quantified and related to five potentially predicting variables: species' occurrence in the species pool, distance to the nearest stand and the life-history traits seed buoyancy, seed production and plant height. 2 From 126 samples, 106 614 individuals of vascular plants developed, 95.8% from vegetative diaspores and 4.2% from seeds. Among these plants, three free-floating, 12 submerged, 22 emergent (aquatic) and 70 riparian (semi-aquatic and terrestrial) species were recorded, respectively, accounting for 24.3%, 71.9%, 1.2% and 2.6% of the total number of viable diaspores trapped. 3 Of the free-floating, submerged and emergent species, 100%, 98.9% and 23.7% of the diaspores were vegetative, respectively, whereas it was 2.9% for riparian species. 4 Diaspores of 79% of the total number of aquatic species and 40% of riparian species observed in the established vegetation were trapped. Minimal dispersal distances ranged from 0 to 6 km. 5 Multiple regression analysis conducted for submerged species, showed that 71% of the variation in the diaspore pool could be predicted by occurrence of species in the vegetation. For emergent species, seed production and occurrence of species explained 54% of the variation, seed production being most important. Mean seed buoyancy of emergent species was higher than that of the other groups. For riparian species, seed production, occurrence and buoyancy explained 48% of the variation in the diaspore pool. Seed production per plant was the most important variable. Linear regression revealed a negative relationship between distance and abundance of the diaspore pool for submerged and riparian species. 6 We conclude that the occurrence of species in the species pool is a significant predictor for the dispersal of free-floating and submerged aquatics that rely on vegetative propagation. Seed production and buoyancy are of additional importance with regard to emergent aquatics. Riparian species with a limited terrestrial dispersal capacity may largely extend their range by hydrochory. That is, if they produce large amounts of (small) seeds and provided that these can reach the water body. Buoyancy and high frequency and abundance in the established vegetation promote this dispersal capacity as well.

Summary1 Restored floodplains and backwaters lacking a viable propagule bank, may need flood pulses to facilitate inward dispersal of diaspores. Temporal patterns of hydrochorous plant dispersal are, however, not well known. 2 Diversity and abundance of diaspores dispersed in a water body over 12 months were quantified using a 200 µ m net in order to: (i) test for a relationship between discharge and the number of species and diaspores dispersed; (ii) examine the effect of seed buoyancy and seed release period on the length of the dispersal period; and (iii) test whether diaspores of species that disperse during a similar period of the year are characterized by similar dispersal and dormancy traits. 3 A total 359 188 individuals of 174 vascular species developed from 144 samples, with most (90%) from vegetative diaspores and only 10% from seeds. Mean number of species and diaspores varied between months in parallel with discharge levels. Stepwise multiple regression analysis showed that both seed buoyancy and seed release influenced dispersal periods. 4 In general, species that dispersed most diaspores in spring and summer had nondormant seeds, a shorter seed release period and a shorter seed dispersal period than species whose dormant seeds dispersed in autumn and winter. Vegetative diaspores were dispersed on average over 8 months, indicating their importance to long-distance dispersal. Several species dispersed both generative and vegetative diaspores, often in different seasons. 5 Our results may assist the planning of regenerative processes in riverine wetlands at landscape scales, as dispersal phenology, and discharge rates must be taken into consideration. Vegetative diaspores may be more important than seeds, although the latter may extend the species dispersal period into other seasons. Temporal heterogeneity in diaspore dispersal influences the identity of diaspores reaching restored habitats.

The morphological variation in a population of Pleuroxus aduncus (Jurine, 1820) from a well in Germany is described. The number of denticles at the postero-ventral corner of the valve are more numerous than normal and abnormalities occur regularly. The observations are discussed in the context of the described variation in number of posteroventral denticles of this species and the causes given for abnormalities in recent literature.

The launch of the Dutch Caribbean Species Register by Naturalis Biodiversity Center (2017)—https://www.dutchcaribbeanspecies.org/—raised the question of which branchiopods originate from this part of the Netherlands. To answer this question, surveys of literature and of the Naturalis collection were conducted. The additional samples (collected in 2003–2005 and 2008) were analyzed. We present an annotated checklist of the Branchiopoda of the Dutch Caribbean.                 The Kingdom of the Netherlands includes the Dutch mainland and six Caribbean islands. From the Caribbean part of the kingdom, an annotated list of all known species is given. Fifteen taxa and three genera have been encountered and the species are discussed. To date, six species of large branchiopods and nine species of cladocerans are known. Two more genera of cladocerans have been found. One species is endemic to Bonaire.

A new species of the symphylan genus Hanseniella Bagnall, 1913 is described. It was found in a hothouse of a small zoo at Almere, the Netherlands. Hanseniella oligomacrochaeta Scheller, 2002 was recorded, for the first time since its description, in another Dutch hothouse. A bibliographic catalogue of all 82 Hanseniella species known to date is presented. How to cite this article: