Posted on 11/06/2025 2:56:29 PM PST by nickcarraway
These species skip the tadpole stage entirely, an incredibly rare phenomenon among toads and frogs.
In A Nutshell
Scientists identified three new toad species in Tanzania that give birth to live babies instead of laying eggs, bringing the global total of live-bearing frogs and toads to just 20 species.
DNA extracted from museum specimens collected in 1899 helped researchers solve a 115-year-old mystery about where these toads actually live, with genetic analysis showing populations previously thought to be one species are actually four distinct species separated by mountain ranges.
The newly described species face serious conservation threats, with ranges as small as 20 square kilometers, making them critically endangered due to habitat loss and deforestation pressures.
These toads evolved viviparity as an adaptation to steep mountain terrain where suitable breeding ponds are scarce, with females carrying developing embryos for months before giving birth to fully formed miniature toads.
Most frogs lay eggs that hatch into tadpoles, but high in Tanzania’s misty mountain forests, a group of toads has abandoned this amphibian tradition entirely. Scientists have just described three new species of tree toads that give birth to fully formed baby toads. No tadpole stage required at all!
Live birth is vanishingly rare among the world’s 8,000-plus frog and toad species. Only 20 anurans worldwide have evolved this reproductive strategy, and 16 of them belong to a single genus called Nectophrynoides found exclusively in Tanzania. The three newly described species bring the total to 16, and each represents a separate evolutionary experiment happening on isolated mountaintops.
An international research team published their findings in the journal Vertebrate Zoology, revealing that what scientists had long considered a single widespread species was actually four genetically distinct species. The discovery came after researchers extracted DNA from museum specimens collected 120 years ago, some sitting in German collections since 1899.
Scientists Extract DNA from Century-Old Museum Specimens The research team faced an unusual challenge: determining which populations belong to which species when the original specimens were collected before World War I. Museum labels from that era were often vague or incorrect, with some specimens simply marked “Southern Tanzania.”
Scientists from the Natural History Museum Denmark, University of Dar es Salaam, and several European institutions used museomics to extract and sequence DNA from 33 preserved specimens in Berlin’s Museum für Naturkunde. These included specimens collected by German naturalist Friedrich Fülleborn from Tanzania’s Southern Highlands between 1899 and 1900.
The team compared this historical genetic material with DNA from 257 modern specimens collected across Tanzania’s Eastern Arc Mountains and Southern Highlands. They also measured 27 different physical characteristics on each toad, from snout length to the shape of enlarged glands on their limbs.
The genetic analysis showed populations living in different mountain ranges had diverged by more than 3% in their mitochondrial DNA, a level of genetic difference that typically indicates separate species evolving independently for millions of years.
Mountain Isolation Creates Three Distinct Species Nectophrynoides luhomeroensis, named after the Luhomero Mountains in Udzungwa Mountains National Park, is the smallest of the three new species. Adults measure 18.4 to 30.0 millimeters in body length. These toads have rhomboid-shaped parotoid glands behind their eyes, and their fingers and toes are more expanded and rounded than their relatives.
Nectophrynoides uhehe, named in honor of the Hehe people living in villages surrounding these forests, is the largest. Some individuals reach 52.5 millimeters in body length. Their parotoid glands form a rough kidney shape and their limbs are covered with distinct, heavily expanded glandular masses. Researchers recorded their advertisement calls, which consist of 25-27 pulses per call.
Nectophrynoides saliensis comes from Sali Forest Reserve in the Mahenge Mountains. Adults range from 20.8 to 34.3 millimeters. Their most distinctive feature is a spearhead-shaped parotoid gland that narrows to a thin point. The species has less distinct glandular masses on its limbs compared to the other two.
Tanzania’s Eastern Arc Mountains function like islands in the sky. Each mountain range is separated from its neighbors by lowland valleys that these forest-dwelling toads cannot cross. Populations became isolated as the mountains formed and forests fragmented, leading each group to evolve independently over millions of years.
The genetic analysis revealed that Nectophrynoides viviparus, the species originally described in 1905, is actually restricted to Tanzania’s Southern Highlands. Populations from the Udzungwa Mountains previously thought to be the same species are genetically distinct by 3.6 to 4.3%.
115-Year-Old Mystery: Specimens in the Wrong Place Part of the research involved solving a geographic puzzle. Some specimens in the original 1905 type series were labeled as coming from Dar es Salaam and Amani, coastal locations where these highland toads don’t actually live.
When the team sequenced DNA from these specimens, they clustered genetically with modern populations from the Uluguru Mountains, hundreds of kilometers from the labeled sites. The location data was likely incorrect, a common problem with colonial-era collections where specimens were often obtained through intermediaries and actual collection sites were never properly recorded.
How These Toads Give Birth Without Water
Viviparity in amphibians requires several dramatic evolutionary changes. Unlike most frogs that release eggs to be fertilized externally in water, viviparous toads mate on land with internal fertilization. Females carry developing embryos in their oviducts for months, nourishing them through specialized maternal tissues similar to a placenta.
The eggs are large and yolky, providing nutrition for developing toadlets. Instead of hatching as aquatic tadpoles with gills, the young develop directly into miniature adults while still inside their mother. When born, they are fully formed terrestrial toads ready to hop away and hunt for food.
This reproductive strategy frees these toads from dependence on water bodies for breeding, an advantage in montane forest and grassland habitats where suitable ponds may be scarce. However, females can produce far fewer offspring than egg-laying species. The tradeoff is that each baby toad has a much higher chance of survival since it doesn’t face the aquatic tadpole stage.
Conservation Status Worsens With New Species Split
The taxonomic revision creates urgent conservation questions. Nectophrynoides viviparus was previously listed as “Least Concern” on the IUCN Red List based on an estimated extent of occurrence of 46,287 square kilometers across multiple mountain ranges.
Breaking this into four separate species drastically shrinks each species’ range. N. viviparus sensu stricto, now restricted to the Southern Highlands, occupies an estimated 304 square kilometers. N. luhomeroensis from the Luhomero Mountains occupies approximately 152 square kilometers. N. saliensis from Sali Forest Reserve has the smallest range at just 20 square kilometers.
Based on these revised distributions, the research team recommends that N. saliensis and N. luhomeroensis should be classified as Critically Endangered, N. viviparus as Endangered, and N. uhehe as Vulnerable. N. saliensis faces particularly serious threats because Sali Forest Reserve is under pressure from deforestation.
Some populations of N. uhehe have already gone extinct. The species was once found in Kiolela Forest Reserve, but that forest fragment no longer exists.
Of the 16 species now recognized in the genus Nectophrynoides, several are already in trouble. N. asperginis recently went extinct in the wild, though captive populations survive. N. poyntoni has had few confirmed sightings since its discovery.
Live birth in frogs represents one of evolution’s more peculiar experiments, a reproductive innovation that evolved independently only a handful of times across hundreds of millions of years of amphibian history. That 80% of the world’s live-bearing anurans belong to a single genus on Tanzanian mountaintops makes Nectophrynoides toads extraordinarily valuable for understanding how complex traits evolve. Losing any of these species means losing a unique solution to the problem of reproducing without water, refined over millions of years of mountain-top isolation.
Paper Summary
Methodology
Researchers examined 257 preserved toad specimens housed in five European museum collections. They took 27 different measurements on each specimen and noted qualitative features like gland shape and skin texture. For genetic analysis, they extracted DNA from tissue samples of both modern specimens and historical type specimens collected between 1899-1900. Some historical specimens required special museomics techniques to retrieve degraded DNA fragments. The team sequenced three mitochondrial gene regions (12S rRNA, 16S rRNA, and cytochrome c oxidase subunit I) totaling about 1,971 base pairs. They used maximum likelihood methods to build evolutionary trees and calculated genetic distances between populations. For two species, they analyzed male advertisement calls, measuring call duration, pulse number, pulse duration, and dominant frequency. They used statistical tests including Principal Component Analysis, Linear Discriminant Analysis, and Analysis of Variance to compare body measurements between populations.
Results
The genetic analysis revealed that Nectophrynoides viviparus sensu stricto from the Southern Highlands forms a distinct clade from all Eastern Arc Mountain populations. Three separate lineages from the Eastern Arc Mountains showed genetic divergences of 3.1-4.8% from N. viviparus and from each other, qualifying them as separate species. Historical type specimens from “Daressalam” and “Amani” grouped genetically with modern Uluguru Mountains populations, not with Southern Highlands toads, indicating the historical locality data was incorrect. Morphologically, the species differ in body size, head proportions, gland shapes, and limb characteristics. Advertisement call analysis showed N. uhehe has significantly more pulses per call (25 versus 13) and shorter intervals between calls compared to N. viviparus sensu stricto. The Linear Discriminant Analysis correctly classified specimens to species with 90.1% accuracy.
Limitations
The study acknowledges several limitations. Sample sizes for some species were small, particularly for N. saliensis (6 adults) and N. luhomeroensis (8 adults), limiting statistical power for morphological comparisons. Specimens were not sexed because external sexual differences in Nectophrynoides are subtle and reliable determination would require dissection, so potential sexual dimorphism could not be analyzed. Advertisement calls were recorded from only two species with limited recordings (N. viviparus: 1 recording with 7 calls; N. uhehe: 2 recordings with 11 calls each), making it difficult to assess the full range of call variation and whether calls reliably distinguish all species. Some historical museum specimens were in poor condition, partially desiccated, or had degraded DNA that produced only short, fragmented sequences. The geographic scope was limited to southern Eastern Arc populations; northern populations from Uluguru, Rubeho, and Nguru Mountains were not fully reassessed and will require separate taxonomic revision. No ecological or behavioral data beyond basic habitat observations were available for most populations.
Funding and Disclosures
The museomics work was funded by the Taxonomiefonds of the Museum für Naturkunde Berlin. Collection work at MUSE was funded by the Bøje Benzon Foundation. Fieldwork for one author was funded by the Science Investment Fund for the Natural History Museum London. The research required permits from the Tanzania Commission for Science and Technology (COSTECH), Tanzania Wildlife Research Institute (TAWIRI), Tanzania Forest Services Agency (TFS), and the University of Dar es Salaam. No competing interests were declared.
Publication Details
Thrane C, Lyakurwa JV, Liedtke HC, Menegon M, Petzold A, Loader SP, Scherz MD (2025) “Museomics and integrative taxonomy reveal three new species of glandular viviparous tree toads (Nectophrynoides) in Tanzania’s Eastern Arc Mountains (Anura: Bufonidae),” published in Vertebrate Zoology 75: 459-485. doi:10.3897/vz.75.e167008. The paper was received July 28, 2025, accepted October 4, 2025, and published November 6, 2025.
How does this help to make dinosaurs?
There aren’t enough OEM parts to make dinosaurs.
Squirt some of these eggs up the butts of male trannies wanting babies.
Turkey baster.
That is very cool. I didn’t know any frogs or toads could do this.
I can’t believe it. An entire science article without even one mention of “climate change.”
Imagine being born, then being 20.
Most disgusting thing I’ve heard all day...still laughing.
What’s fascinating is the adaptation to environment.
They sound like a right jolly tribe.
Absolutely. Sounds Lamarckian.
Adaptation isn’t Lamarckism.
And subsequent speciation in isolation from each other....
I’ve always been fascinated by Rupert Sheldrake’s theory of morphic resonance.
Maybe there’s more than material inheritance going on in phenomena like this.
I think plain old genetic drift can account for the speciation. The whole ovoviviparous thing is common enough in fish; I wouldn’t think it that far a stretch in amphibians. It may have been far more common in species long since lost.
I don’t think anything happens by chance.
I do think a kind of intelligence exists in all of Nature and Creation, and it has ways of responding to environment.
Fine. But it’s not science.
Do you think ‘anthropogenic climate change’ is ‘science’?
The ‘Great God Science’ isn’t always correct, and has often had to revise its proclamations.
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