Limia mandibularis, a new livebearing fish of the family Poeciliidae is described from Lake Miragoane in southwestern Haiti on Hispaniola. The new species differs from all other species in the genus Limia by the presence of a well-developed lower jaw, the absence of preorbital and preopercular pores, and preorbital and preopercular canals forming an open groove each. The description of this new Limia species from Lake Miragoane confirms this lake as an important center of endemism for the genus with a total of nine described species so far.

Objective The Caribbean is an important global biodiversity hotspot. Adaptive radiations there lead to many speciation events within a limited period and hence are particularly prominent biodiversity generators. A prime example are freshwater fish of the genus Limia, endemic to the Greater Antilles. Within Hispaniola, nine species have been described from a single isolated site, Lake Miragoâne, pointing towards extraordinary sympatric speciation. This study examines the evolutionary history of the Limia species in Lake Miragoâne, relative to their congeners throughout the Caribbean. Results For 12 Limia species, we obtained almost complete sequences of the mitochondrial cytochrome b gene, a well-established marker for lower-level taxonomic relationships. We included sequences of six further Limia species from GenBank (total N  = 18 species). Our phylogenies are in concordance with other published phylogenies of Limia. There is strong support that the species found in Lake Miragoâne in Haiti are monophyletic, confirming a recent local radiation. Within Lake Miragoâne, speciation is likely extremely recent, leading to incomplete lineage sorting in the mtDNA. Future studies using multiple unlinked genetic markers are needed to disentangle the relationships within the Lake Miragoâne clade.

The Caribbean is one of the most important biodiversity hotspots on the planet due to the high level of species diversity and endemism in plants and animals. As elsewhere, adaptive radiations in the Caribbean lead to many speciation events within a limited period and hence are particularly prominent biodiversity generators. The general prediction from Island Biogeography that relates species richness to island size is valid for livebearing fishes in general in the Greater Antilles, where larger islands have higher numbers of species mainly due to in situ speciation. A prime example of this speciation process can be seen in the genus Limia, endemic to the Greater Antilles. Within Hispaniola, nine species have been described from a single isolated site, Lake Miragoâne, pointing towards extraordinary sympatric speciation in Limia. Few studies have examined the evolutionary history of the fishes found in Lake Miragoâne. Here, we address the gaps in present knowledge by providing a preliminary phylogeny of Limia and testing whether the species found in Lake Miragoâne may originated from an in situ radiation. We targeted the mitochondrial cytochrome b gene, a well-established marker for lower-level taxonomic relationships for which we obtained almost complete sequences for 13 species. The general topology of the phylogenies we produced are in concordance with other published phylogenies of Limia. There is also strong support that the species found in Lake Miragoâne in Haiti are indeed monophyletic (BS=97; PP=1.0), confirming the hypothesis of a recent local radiation. Within Lake Miragoâne, speciation is likely extremely recent, leading to incomplete lineage sorting in the mtDNA. Future studies are needed using multiple unlinked genetic markers to disentangle the relationships within the Lake Miragoâne clade.

Feeding is relevant to every aspect of animal life and is tightly linked to the ecological niche a species occupies. In concordance with the enormous diversity found in teleost fishes, feeding specialisations are also abundant in this group. One example for this is the order Cyprinodontiformes. This is the most diverse and speciose order of freshwater fishes within the Atherinomorphae. More than 1350 species are known in this order, which are distributed in temperate and tropical regions of the world usually inhabiting shallow freshwater environments or coastal brackish waters (Malabarba & Malabarba, 2020). The Cyprinodontiformes contain approximately

The population structure of Limia zonata (Nichols, 1915) was studied in four locations in the Maimón River, Monseñor Nouel province, Dominican Republic. The sex and adult-juveniles ratio was calculated for all sampled localities. It was found that the sex ratio of L. zonata was significantly different from 1: 1 and is biased towards females (1.0: 1.6). Juvenile fish were more abundant and frequent than adults (69.3%). More than 800 fish were measured and weighed to analyze the frequency of size classes, morphometry and body condition. Ten size classes were distinguished that vary in frequency according to sex. Total length of the specimens ranged from 6.50 to 65.69 mm, while weight varied between 0.004 and 3.941 g. The morphology varied between sexes and a pronounced sexual dimorphism was found. All the morphometric variables studied showed a high level of association (r). The adjustment of the regression models (r2) of the morphometric relationships was between 85% and 99%. The relationship between the standard length and the total weight was reflected in the rates of growth. The Relative Condition Factor (Kn) demonstrated the good state of health of this fish population, but also variations between the sexes were detected.