Draft genome of the Brazilian railroad worm Phrixothrix hirtus E.Olivier (Phengodidae: Coleoptera)

The Neotropical region is the richest in bioluminescent Coleoptera species, however, its bioluminescence megadiversity is still underexplored in terms of genomic organization and evolution, mainly within the Phengodidae family. The railroad worm Phrixothrix hirtus is an important biological model and symbolic species due to its bicolor bioluminescence, being the only organism that produces true red light among bioluminescent terrestrial species. Here, we performed the partial genome assembly of P. hirtus, combining short and long reads generated with Illumina sequencing, providing an important source of genomic information and a framework for comparative genomic analyses for the evaluation of the bioluminescent system in Elateroidea. The estimated genome size has ∼3.4Gb, 32% of GC content, and 67% of repetitive elements, being the largest genome described in the Elateroidea superfamily. Several events of gene family expansions associated with anatomical development and morphogenesis, as well as distinct odorant-binding receptors and retrotransposable elements were found in this genome. Similar molecular functions and biological processes are shared with other studied species of Elateriformia. Common genes putatively associated with bioluminescence production and control, including two luciferase genes that displayed 7 exons and 6 introns, and genes that could be involved in luciferin biosynthesis were found, indicating that there are no clear differences about the presence or absence of gene families associated with bioluminescence in Elateroidea. In P. hirtus the conversion of L- to D-luciferin seems to involve additional steps using a Palmitoyl-CoA thioesterase instead of an Acyl-CoA synthetase, which was found in Lampyridae species.