A new species of Cypris (Crustacea: Ostracoda) from the Iberian Peninsula and the Balearic Islands, with comments on the first ostracod named using the Linnean system.

The genus Cypris, considered the oldest ostracod generic name erected using the Linnean system, comprises a reduced number of large-bodied species, mostly found in Africa and Asia. Only six of them are known to occur in Europe. Here we describe a new species, Cypris pretusi sp. nov., collected in small temporary streams and ponds along the Eastern Iberian Peninsula and Minorca (Balearic Islands). The new species is very close to the type species of the genus, Cypris pubera O.F. Müller, 1776, but differs from it in having a set of smaller subequal spines on the posterior edge of the valves, by the absence of conspicuous spines along the front edge, and by the beak-like frontal shape of its carapace in dorsal view, similar to Cypris decaryi Gauthier, 1933. Soft parts are very similar to the type species, but it differs in having shorter swimming setae on the second antennae. Molecular analyses of the COX1 region support its status as a species distinct from C. pubera and closer to Cypris bispinosa Lucas, 1849, also providing evidence for a separation of C. pubera s.l. in two clades, one of which is here considered to correspond to Cypris triaculeata Daday, 1892. We discuss the relationships of C. pretusi sp. nov. to other members of the genus and its possible origin from nearby biogeographic regions (probably Africa or Asia) and provide a key to species of Cypris found in Europe. We also discuss the relationship between Monoculus concha pedata (= M. conchaceus), the first ostracod named by Linnæus, and Cypris pubera, the type species of the genus, described by Müller in 1776 and considered by him the same species as the one first named by Linnæus.

Breaking the temperature-size rule: thermal effects on growth, development and fecundity of a crustacean from temporary waters.

The temperature-size rule (TSR) is a well-established phenomenon to describe the growth response of ectotherms to temperature by which individuals maintained at low temperatures grow more slowly, but attain a larger size upon maturity. Although there are adaptive and non-adaptive theories about the plasticity of body size in response to temperature, these cannot be applied to all ectotherms, and little is known about the changes in growth and development rates through ontogeny. The ostracod species Heterocypris bosniaca, an inhabitant of freshwater temporary ponds, was used to examine the growth and development rates of its nine growth stages and female fecundity at four different temperatures (15°C, 20°C, 25°C and 30°C). The development rate of this species accelerates with increasing temperature, reaching a maximum value at 25°C. The growth factor has a reverse-TSR in younger instars, and the typical TSR is followed only in the last two moults, resulting in non-monotonic response of adult size to temperature. Fecundity (total offspring per female) was not directly related to adult size and was generally higher at lower temperatures. Our results agree with recent research showing that the TSR may vary during ontogeny, and may not be a general trend in ostracod species from temporary waters. Indeed, adult carapace size seems to follow the pattern of a thermal reaction norm, probably influenced by the reduction of oxygen bioavailability at low temperature and the drastic increase in metabolic demand at the upper extreme of the thermal gradient.

Invasion biology in non-free-living species: interactions between abiotic (climatic) and biotic (host availability) factors in geographical space in crayfish commensals (Ostracoda, Entocytheridae).

In invasion processes, both abiotic and biotic factors are considered essential, but the latter are usually disregarded when modeling the potential spread of exotic species. In the framework of set theory, interactions between biotic (B), abiotic (A), and movement-related (M) factors in the geographical space can be hypothesized with BAM diagrams and tested using ecological niche models (ENMs) to estimate A and B areas. The main aim of our survey was to evaluate the interactions between abiotic (climatic) and biotic (host availability) factors in geographical space for exotic symbionts (i.e., non-free-living species), using ENM techniques combined with a BAM framework and using exotic Entocytheridae (Ostracoda) found in Europe as model organisms. We carried out an extensive survey to evaluate the distribution of entocytherids hosted by crayfish in Europe by checking 94 European localities and 12 crayfish species. Both exotic entocytherid species found, Ankylocythere sinuosa and Uncinocythere occidentalis, were widely distributed in W Europe living on the exotic crayfish species Procambarus clarkii and Pacifastacus leniusculus, respectively. No entocytherids were observed in the remaining crayfish species. The suitable area for A. sinuosa was mainly restricted by its own limitations to minimum temperatures in W and N Europe and precipitation seasonality in circum-Mediterranean areas. Uncinocythere occidentalis was mostly restricted by host availability in circum-Mediterranean regions due to limitations of P. leniusculus to higher precipitation seasonality and maximum temperatures. The combination of ENMs with set theory allows studying the invasive biology of symbionts and provides clues about biogeographic barriers due to abiotic or biotic factors limiting the expansion of the symbiont in different regions of the invasive range. The relative importance of abiotic and biotic factors on geographical space can then be assessed and applied in conservation plans. This approach can also be implemented in other systems where the target species is closely interacting with other taxa.