Ancestral transoceanic colonization and recent population reduction in a nonannual killifish from the Seychelles archipelago.

Whether freshwater fish colonize remote islands following tectonic or transoceanic dispersal remains an evolutionary puzzle. Integrating dating of known tectonic events with phylogenomics and current species distribution, we find that killifish species distribution is not explained by species dispersal by tectonic drift only. Investigating the colonization of a nonannual killifish (golden panchax, Pachypanchax playfairii) on the Seychelle islands, we found genetic support for transoceanic dispersal and experimentally discovered an adaptation to complete tolerance to seawater. At the macroevolutionary scale, despite their long-lasting isolation, nonannual golden panchax show stronger genome-wide purifying selection than annual killifishes from continental Africa. However, progressive decline in effective population size over a more recent timescale has probably led to the segregation of slightly deleterious mutations across golden panchax populations, which represents a potential threat for species preservation in the long term.

Developmental ecology of annual killifish Millerichthys robustus (Cyprinodontiformes: Cynolebiidae).

Populations of annual killifishes persist in temporary water bodies over the dry season through the expression of diapause in their drought-resistant embryos. Environmental cues may influence expression of the diapause phenotype during embryonic incubation. Millerichthys robustus is the only annual killifish distributed in North America. The aim of this review is to analyze the ecology of M. robustus development and contrast this with that of annual killifishes in austral locations. The temporary water bodies inhabited by M. robustus present the following environmental conditions: flood, drought, and humidity. During the flooding period, the environment presents the lowest temperatures, shortest photoperiod, and highest precipitation, and embryos were found in diapause I. The drought period features the highest temperatures and lowest precipitation, and embryos were found in diapause II. In contrast, during the humid period at the beginning of the rainy season, embryos were found in diapause I, II, and III, associated with the longer photoperiod and high temperatures. These dynamics of the diapause phenotypes can be explained by a combination of the strategies of phenotypic plasticity during flood and drought periods, and bet-hedging during the humid period. Moreover, the microenvironmental conditions in which embryos were buried could influence developmental trajectories. Developmental Dynamics 246:802-806, 2017. © 2017 Wiley Periodicals, Inc.

Four new species of the Indo-Burmese genus Badis from West Bengal, India (Actinopterygii: Perciformes: Badidae).

Four new species of Badis are described from West Bengal, India. Badis andrewraoi, new species, is diagnosed by a combination of characters which include absence of a black caudal-fin margin, absence of a conspicuous dark blotch on pectoral-fin base, absence of cleithral and opercular blotches, absence of a blotch on the dorsolateral aspect of the caudal peduncle, absence of an ocellus on the caudal-fin base, presence of a conspicuous median black caudal peduncle blotch, a medially broader posterior-most bar, displaying as a partially absorbed second median caudal peduncle blotch, presence of an additional bar anteriorly, and vertical bars restricted to lower half of body and never forming large blocks. Badis autumnum, new species, is diagnosed by a combination of characters which include two autapomorphies: presence of a blotch above the base of the opercular spine, and of a conspicuous dark blotch on pectoral-fin base. Additionally, it presents a black caudal-fin margin, outlining entire fin, absence of a cleithral blotch, absence of a blotch on the dorsolateral aspect of the caudal peduncle, absence of an ocellus on the caudal-fin base, presence of a conspicuous median black caudal peduncle blotch, a medially broader posterior-most bar, displaying as a partially absorbed second median caudal peduncle blotch, and presence of an additional bar anteriorly. Badis kyanos, new species, is diagnosed by a combination of characters which include absence of a conspicuous dark blotch on pectoral-fin base, absence of cleithral and opercular blotches, absence of a blotch on the dorsolateral aspect of the caudal peduncle, absence of an ocellus on the caudal-fin base, presence of a conspicuous median black caudal peduncle blotch, a medially broader posterior-most bar, displaying as a partially absorbed second median caudal peduncle blotch, presence of an additional bar anteriorly, its vertical bars forming large, fragmented black blocks dorsolaterally and ventrolaterally, and a unique stress colouration consisting of a dark grey body, metallic dark blue operculum, flanks almost entirely devoid of bars, large, fragmented black blocks dorsolaterally, and absence of a black caudal-fin margin. Based on similarities in colour pattern and biometrics they are deduced to be closely related and form a new species group, which we herein define. The three species are divergent and diagnosable from each other and represent valid evolutionary species. The fourth species represents a cryptic unit that was heretofore unrecognised and considered as the most widespread species of the genus, B. badis. We describe this lineage as Badis soraya, new species, and find it belongs to the B. badis species group. It can be diagnosed by a combination of characters which include absence of opercular blotches, absence of a blotch on the dorsolateral aspect of the caudal peduncle, absence of an ocellus on the caudal-fin base, presence of a cleithral blotch, presence of a small oval black blotch medially on caudal peduncle, interorbital width 6.3-8.8 % SL, dorsal-fin spines XIV-XVI, scales in lateral row 25-27, and vertebrae number 27.

A new annual killifish, Moema beltramonorum (Cyprinodontiformes: Rivulidae) from the Amazon basin, Bolivia.

A new annual killifish species, Moema beltramonorum, is described from a seasonal swamp next to arroyo Crespo, belonging to Ro San Martin, a tributary of Ro Itnez, Amazon River basin, Bolivia. The new taxon presents an unique combination of male colour pattern characters not present in any congener, and an unique caudal fin coloration.

Validation of Aphyosemion lorai and Caeruleamsemion; a new species and subgenus of killifish (Cyprinodontiformes: Nothobranchiidae), from the continental region of Equatorial Guinea.

N/A.

Laimosemion leticia (Teleostei: Cyprinodontiformes: Rivulidae), a new species from the upper Rio Amazonas, Southern Colombia.

Laimosemion leticia is described from the Rio Tacana drainage, upper Rio Amazonas basin, Southern Colombia. The new species was found in a shallow swamp within a tropical rainforest in the vicinity of Leticia, capital of the department of Amazonas and southernmost municipality of Colombia. This miniature species is considered to be a member of the Owiyeye subgenus, which is diagnosed by a unique frontal squamation. Laimosemion leticia can be distinguished from all other species of the genus by the unique colour pattern on the unpaired fins. The new species appears related to L. jauaperi, L. uatuman and L. ubim due to the similar flank colour pattern in males, but is easy distinguished by coloration of the unpaired fins and morphological characters.

Badis laspiophilus, a new miniature addition to the ichthyofauna of West Bengal, north-eastern India, with observations on its ecology and preliminary notes on its ethology (Actinopterygii: Perciformes: Badidae).

Badis laspiophilus is described from the Torsa River drainage, West Bengal, India. It can be distinguished from congeners by a combination of characters which include a small size (15.7-21.0 mm SL), 14-16 circumpeduncular row scales, interorbital width 6.7-8.9% SL, upper and lower jaws 8.2-9.2 and 10.2-13.4% SL, respectively, presence of two dorsal-fin blotches and a single round blotch on the anal fin, and absence of cleithral, opercle and dorsolateral caudal peduncle blotches. Its benthic ecology is discussed and the Badis singenensis species group is diagnosed, of which B. laspiophilus and B. singenensis are considered members.

Extremely short lifespan in the annual fish Nothobranchius furzeri.

Evolutionary theories of senescence postulate that lifespan is determined by the age-dependent decrease in the effects of natural selection. Factors that influence survival and reproduction at early life stages have a larger impact on fitness than factors that influence later life stages. According to these views, selection for rapid sexual maturation and a steep age-dependent decrease in fitness drive the evolution of short lifespans. Here, we report on the survival trajectory of Nothobranchius furzeri (Pisces: Ciprinodontidae): a member of a group of annual species found in temporary bodies of water whose life expectancy in the wild is limited to a few months. We find that maximum survival of N. furzeri in the laboratory is less than 12 weeks. The temporal trajectory of survival shows an age-dependent increase in the mortality rate that is typical of organisms with defined lifespans. The lifespan of N. furzeri is exceptionally short for a vertebrate: owing to its small size and the possibility of propagation in captivity, N. furzeri could be used as a convenient model for ageing research.

Potential negative impacts and low effectiveness in the use of African annual killifish in the biocontrol of aquatic mosquito larvae in temporary water bodies.

Commentary and discussion on a recent paper promoting the use of Nothobranchius guentheri, a small African annual fish from the Island of Zanzibar as a tool to control mosquito larvae in temporary bodies of freshwater throughout Africa is presented.Arguments on major points; (1) expected low success of annual fish introductions, (2) low success of mosquito control in the field, (3) ecological threats, and (4) ethical issues are detailed.Despite serious problems with mosquito-borne diseases in tropical Africa and elsewhere, we encourage responsible means of biological control of parasite vectors. We show that effectiveness of Nothobranchius translocations is low (the previous attempts failed), likelihood of effective mosquito larvae control under field condition is negligible and ecological threats from Nothobranchius translocations from within and outside the naturally occurring range are serious. We advocate against the proposed next step of the project, i.e. field trials in Tanzania.