Development of the smooth newt, Lissotriton vulgaris, as observed in a garden pond during lockdown.

Background: Lissotriton vulgaris ("smooth newt") was an important organism for experimental embryology, especially in the early 20th century. The stages of development of L. vulgaris from the appearance of the first cleavage to metamorphosis have previously been described, but only through drawings.

Results: Referring to Glaesner's staging and utilizing a makeshift lockdown laboratory, this study documents the development of L. vulgaris embryos in a small garden pond in Surrey, UK. This study describes varying developmental rates between individuals, identifies pigmented cells in close proximity/contributing to the heart, describes early gill development and reports a case of spontaneous, non-conjoined newt twins.

Conclusions: While pigmentation in the heart has been reported in some amphibians, no pigmentation within urodele hearts has been documented to date. Furthermore, although the literature on conjoined twinning in amphibia is extensive, separate, non-conjoined twinning is largely unexplored in the literature. This study invites further research into understanding of these topics.