Casting light out of shadows: Assessing the coverage of data on endemic firefly distribution in the Atlantic Forest

Abstract

The Atlantic Forest holds the greatest diversity of fireflies on Earth. Although the knowledge about lampyrids in the Atlantic Forest has increased in the last 10 years thanks to the efforts of new taxonomists and ecologists, both the total number of species and their geographic ranges remain largely unknown. Furthermore, the Atlantic Forest has been facing intense deforestation since the XV century, and now only 23 % of the natural vegetation cover remains, resulting in high vulnerability of its endemic species. Here, we assess the quality and coverage of the information available on the distribution of Lampyridae fireflies; i.e. the extent of the so-called Wallacean shortfall. To do this, we used a database that comprises 3010 records with geospatial and taxonomic information to evaluate the overall coverage of the geographical and environmental distribution of fireflies in the Atlantic Forest. Our assessment shows that the knowledge of Atlantic Forest's firefly diversity and distribution presents significant spatial and climatic biases. Firefly species remain largely under-collected in the Atlantic Forest; only around 16 % of its grid cells at a 50 km scale are well-sampled, and most of them are located in the Serra do Mar bioregion. The location of well-sampled cells is conditioned by recorders’ survey bias and is particularly biased towards protected areas, large forest remnants, the proximity to institutions holding entomological collections, and light-polluted sites surrounding urban spaces. Our findings also highlight that a considerable number of firefly species may remain undiscovered, which adds to the lack of reliable information on the geographic location of many valid species. Based on this assessment, we further point to areas where more sampling effort would provide maximum benefits in terms of geographical and environmental coverage, thus maximizing its value for biodiversity knowledge and conservation.