Freshwater rock pools: a review of habitat characteristics,faunal diversity and conservation value

1. In the light of the recent surge of interest in small and often temporary wetlands as model systems for ecological and evolutionary research, this article reviews current knowledge on freshwater rock pools and their fauna. 2. Freshwater rock pools occur all over the globe in all major biomes and depend mainly on precipitation for filling. Rock pool clusters are some of the more persistent and oldest freshwater habitats worldwide. Interactions between climate and geology (e.g. limestone, sandstone, granite) generally determine the morphology and hydrology of rock pool habitats, with hydroperiods ranging from several days up to the whole year. Pool volume is usually small, resulting in strongly fluctuating environmental conditions, low conductivity and wide variations in pH (from 4.0 to 11.0) and temperature (from freezing point to 40 °C) often with well‐marked diel cycles. The highly variable environmental conditions, combined with the unpredictability of the flooding regime, require high stress tolerance of the inhabitants, with adaptations for surviving the dry phase such as the production of resistant stages and active emigration followed by recolonisation. 3. About 460 aquatic animal species have been recorded from freshwater rock pools around the world. Approximately 170 of these are passive dispersers, which mainly disperse as resting stages via wind and overflow of water between pools. Successful long distance dispersal seems limited. This group is composed mainly of rock pool specialists with a high degree of endemicity. The remaining taxa can be considered active dispersers, with migration usually restricted to the adult stage. Often these taxa are broadly distributed and occur in a wide range of temporary habitats in addition to rock pools. 4. The inherent characteristics of freshwater rock pools, such as their simple structure and occurrence on similar substrata all over the world, facilitate comparison of research results and promote rock pools as model systems for ecological and evolutionary research. Nevertheless, despite their potential as model systems, the unique fauna and their importance as sources of freshwater in dry countries, the ecology of freshwater rock pools remain virtually unexplored in large parts of the world.     

Successional phases and species replacements in freshwater rock pools: towards a biological definition of ephemeral systems

1. In temporary aquatic habitats, time is probably the dominant environmental factor affecting community composition, mainly by setting constraints on colonization success and the replacement of taxa over time. The mechanism and effect of a decreasing inundation period on community development, mostly in terms of truncation, are still poorly documented. The permanent and ephemeral components of temporary communities are expected to be differently influenced by the degree of persistence of the habitat. 2. To study the effect of time on invertebrate community assembly and dynamics in a short duration type of temporary aquatic habitat, we monitored 16 ephemeral rock pools which persisted from less than a week to about 1 month at two rock pool sites in semi‐arid south‐eastern Botswana. Data were collected every 2 days during a full inundation cycle. 3. All communities were initially assembled by permanent residents recolonizing the habitat from egg banks and were later joined by actively dispersing ephemeral taxa. Species replacements only occurred in two pools. Concurrent with a decrease in the densities of Branchipodopsis wolfi, population sizes of Leberis sp. and Culicidae (Aedes sp. and Anopheles sp.) increased in these pools. Although it was possible to distinguish two successive phases at one rock pool site, community assembly was generally a gradual process determined by dispersal strategies of the inhabitants. Additional rains after initial filling triggered dispersal by ephemeral taxa, mainly Micronecta youngiana and Hydroglyphus infirmus, and positively influenced colonization success. 4. Decreasing persistence shortens community development down to a critical point below which lack of time eliminates the possibility of species replacement. Based on these findings, we define ephemeral waters as aquatic habitats lacking species replacements. Other temporary water types have a relatively longer persistence, permitting successional replacement of species.     

Revision of Pseudocorinna Simon and a new related genus (Araneae: Corinnidae): two more examples of spider templates with a large range of complexity in the genitalia

The genus Pseudocorinna Simon, 1910 is revised. The type species Pseudocorinna rutila Simon, 1910 from Guinea‐Bissau and Pseudocorinna septemaculeata Simon, 1910 from Bioko are redescribed. No material could be found of Pseudocorinna gracilior Simon, 1910 from Bioko which is to be considered nomen dubium. The genus further contains 27 species which are described as new: Pseudocorinna alligator, Pseudocorinna amicorum, Pseudocorinna amphibia, Pseudocorinna banco, Pseudocorinna bilobata, Pseudocorinna brianeno, Pseudocorinna celisi, Pseudocorinna christae, Pseudocorinna cymarum, Pseudocorinna doutreleponti, Pseudocorinna eruca, Pseudocorinna evertsi, Pseudocorinna febe, Pseudocorinna felix, Pseudocorinna gevaertsi, Pseudocorinna incisa, Pseudocorinna juakalyi, Pseudocorinna lanius, Pseudocorinna lobelia, Pseudocorinna natalis, Pseudocorinna naufraga, Pseudocorinna okupe, Pseudocorinna orientalis, Pseudocorinna perplexa, Pseudocorinna personata, Pseudocorinna ubicki, and Pseudocorinna victoria. The genus is characterized by the wide carapace and sternum and the dense network of dark warts on all sclerites of the prosoma. These structures are apparently outlets of underlying glands producing a gel‐like substance. The genus is restricted to the West and Central African forest area, ranging from Guinea‐Bissau to the eastern Democratic Republic of Congo. The species are mainly found in very wet, temporarily inundated forests. A cladistic analysis strongly supported the erection of a new, closely related genus, Crinopseudoa gen. nov. , with very similar habitus but with poorly developed warts that have kept their original hair‐socket function. This genus contains 11 species, all of which are new, and has a distribution restricted to the West‐African refuge areas around Liberia and Cameroon. The type species is Crinopseudoa bong from Liberia. It further contains Crinopseudoa billeni, Crinopseudoa bongella, Crinopseudoa caligula, Crinopseudoa catharinae, Crinopseudoa ephialtes, Crinopseudoa flomoi, Crinopseudoa leiothorax, Crinopseudoa otus, Crinopseudoa paucigranulata, and Crinopseudoa titan. Both genera can be regarded as examples of successful somatic templates with a large range of morphologically different genitalia corroborating the ‘mate check’ hypothesis. Illustrated keys to the species of both genera are provided. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 271–350.