For every rule of nature, even those that seem “carved in stone” to us, there is always an exception. Mammals, for example, give birth to live young – but the platypus lays eggs. We thought that all amphibians laid eggs, but no: there is a genus of toads endemic to Tanzania, Nectophrynoideswhich has the unique characteristic of being ovoviviparous, and of giving birth to already formed small toads that do not pass through the tadpole stage.
Now we have discovered three new species, described in a study published in Vertebrate Zoology.
Hunting for new species. The genre Nectophrynoides was described exactly a century ago, but until 2016 it was thought to contain a single species, Nectophrynoides viviparusdescribed even in 1905 when the genus did not yet exist.
Ten years ago, however, in the magazine Evolution from the University of Oxford, a study came out that questioned the uniqueness of N. viviparusand suggested that the genus may contain several species, distributed throughout the country.
What is museonomics. Since then the hunt for new species has started: so far 16 have been identified, including the last three just described. Which have been elevated to species thanks to the study of hundreds of specimens preserved in museums around the world: the technique used is called “museonomics”, and consists, as the name suggests, in studying the DNA of a species using the collections of different scientific institutions. For the record, the three new species are called Nectophrynoides saliensis, Nectophrynoides luhomeroensis And Nectophrynoides uhehe.
Counts to update. All three species of these toads, together with the thirteen previously identified, have the characteristic of being ovoviviparous: instead of laying eggs (which then become tadpoles and finally adults), they incubate them in the womb and make them hatch there, giving birth to “small adults”. This is a rarity among frogs and toads: only 16 species Nectophrynoidesin addition to four other species belonging to other genera, practice ovoviviparity among amphibians.
In addition to adding three new toad species to the tally of ovoviviparous amphibians, the study also raises a conservation question. As long as we thought that Nectophrynoides it was a single species with a very large range, we had never had any problems with its survival; now that we know that there are more species, and with more restricted habitats, we must re-evaluate their status and understand whether we need to take measures to avoid what happened, for example, to Nectophrynoides asperginisanother ovoviviparous species that became extinct in 2009 following an epidemic of fungal origin.
