Novel type of egg-clustering in threadsnakes (Serpentes: Leptotyphlopidae)

Abstract Snakes lay their eggs in clutches of different size, which are usually attached to each other forming a cluster. Egg-clustering is widespread phenomenon across alethinophidian snakes, mostly recorded Pythonoidea and caenophidian clades. Here we report new type egg-clustering for threadsnakes (Leptotyphlopidae) that departs from the type. We found females Epictia australis Leptotyphlops sylvicolus connected through filament, dubbed it ‘string-egg clustering’. The histomorphology filament linking E. showed an outer calcareous layer underlain by thick collagen fibers, demonstrating integral part eggshell formed during its deposition process oviduct. String seems be present only among species belonging both subfamilies threadsnakes, Epictinae Leptotyphlopinae. alethinophidians has been demonstrated have several advantages embryo development post-hatching survival, including fixing position within egg, protection against predators, embryo-to-embryo communication. presence connecting leptotyphlopid might relevant maintaining avoid dispersion egg nesting site, potentially transmission physical cues. Thus, hypothesize string-egg clustering constitutes advantageous reproductive trait threadsnakes.