3種の新ヒキガエルがオタマジャクシ段階を飛ばして直接出産(Three New Toad Species Skip the Tadpole Phase and Give Birth to Live Toadlets)

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2025-11-06 コペンハーゲン大学(UCPH)

コペンハーゲン大学を中心とする国際研究チームは、アフリカ東部タンザニアでオタマジャクシ期を持たずに直接幼体を産むカエル3新種を発見した。これらは樹上性ヒキガエル属(Nectophrynoides)に属し、雌が体内で受精・発生を行い、完全な小型ヒキガエルを出産する極めて稀な「胎生型両生類」である。DNA解析には120年前の標本を用いたミュゼオミクス手法を採用し、形態・遺伝の両面から新種を同定。発見地の東アーク山地は急速な森林伐採や採掘により生息地が断片化しており、多くの種が絶滅の危機に瀕している。研究は、進化多様性の理解とともに、アフリカ固有両生類の緊急保全の必要性を訴えている。成果はVertebrate Zoology誌に掲載。

<関連情報>

博物館学と統合分類学により、タンザニアの東アーク山脈(無尾目:ヒキガエル科)に腺胎生樹上ヒキガエル(Nectophrynoides )の新種3種が発見された Museomics and integrative taxonomy reveal three new species of glandular viviparous tree toads (Nectophrynoides) in Tanzania’s Eastern Arc Mountains (Anura: Bufonidae)

Christian Thrane, John V. Lyakurwa, H. Christoph Liedtke, Michele Menegon, Alice Petzold, Simon P. Loader, Mark D. Scherz
Vertebrate Zoology  Published:06 nov 2025
DOI:https://doi.org/10.3897/vz.75.e167008

3種の新ヒキガエルがオタマジャクシ段階を飛ばして直接出産(Three New Toad Species Skip the Tadpole Phase and Give Birth to Live Toadlets)

Abstract

For the last century, herpetologists have referred to any Nectophrynoides Noble, 1926 toad characterized by a large, robust body, with large, distinct parotoid glands, as Nectophrynoides viviparus (Tornier, 1905). Consequently, Nectophrynoides viviparus is also considered to have the broadest distribution of all its congeners, with populations ranging from the Tanzanian Southern Highlands, close to the Tanzania-Malawi border, through the Udzungwa and Mahenge Mountains in the south to Uluguru, Rubeho, and Nguru Mountains in the central part of the Eastern Arc Mountains. However, there is underappreciated morphological diversity within what is generally referred to as N. viviparus, and various populations are isolated by large distances and geographical barriers. Recent molecular studies have shown that N. viviparus from the Southern Highlands, the type locality, is genetically distinct from all other N. viviparus populations in the Eastern Arc Mountains, suggesting the existence of a species complex warranting taxonomic revision. Here, we present an integrative taxonomic assessment of southern populations by supplementing the genetic results with the analysis of morphometric and morphological data for 257 specimens assigned to N. viviparus, including museomic data for name-bearing types. Based on the results, we describe three new species from the N. viviparus species complex, covering the southern Eastern Arc Mountains populations. Together with a revised morphological key to the genus and a gazetteer of known populations, we provide Extent of Occurrence and Area of Occupancy for N. viviparus sensu stricto and the new species to investigate their conservation status compared to other members of the genus.

生物環境工学
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