The metamorphic fate of supernumerary caudal vertebrae in South Asian litter frogs (Anura: Megophryidae)
The metamorphic fate of supernumerary caudal vertebrae in South Asian litter frogs (Anura: Megophryidae)
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DOI：
10.1111/j.1469-7580.2007.00757.x
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发表时间：
2007-09
影响因子：
2.4
通讯作者：
G. R. Handrigan;R. Wassersug
中科院分区：
文献类型：
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作者：
G. R. Handrigan;R. Wassersug
Megophryidae的蝌蚪，一个南亚的窝蛙家族，是无尾类动物中独一无二的，因为它们的尾部骨骼扩张，其中包括额外的椎体。这些椎骨的数量在家庭中变化很大，Leptobrachella的蝌蚪有多达30个，Leptolalax只有5个。椎体形态也很多变，从完整的脊索周围椎体到不完整的骨化。然而，这种幼虫巨蛤尾部骨骼学的变化在成体形态中并不明显。变性后的窝蛙有一个典型的无尾类中轴骨骼，总是由八个骶前椎骨，一个骶椎和骶后的尾柱组成。为了解决这种不协调的生活阶段之间，并确定精确的变质命运的多余尾椎骨的megophryids，我们检查了属Leptobrachella，Leptolalax，Ophryophryne和Megophrys的变质标本。在所有四个，尾部幼虫骨骼经历了大规模的减少，只留下尾骨和下索不变。尾椎体明显退化的破骨细胞，以前没有牵连在无尾类动物变态过程中的椎骨重塑。在Megophrys和Ophryophryne变质，骶前中心也进行再吸收，符合epichordal模式的椎体形成。保护megophryid成人轴骨在面对广泛的幼虫骨骼多样性揭示了变态的作用，约束无尾类形态。
Tadpoles of the Megophryidae, a South Asian family of litter frogs, are unique among anurans by virtue of their expanded caudal skeletons, which include supernumerary vertebral centra. The number of these vertebrae varies widely within the family, with tadpoles of Leptobrachella having as many as 30 and Leptolalax only five. Vertebral morphology is also quite variable, ranging from complete, perichordal centra to fragmentary ossifications. This variation in the caudal osteology of larval megophryids, however, is not manifested in the adult morphology. Post‐metamorphic litter frogs have a typical anuran axial skeleton, invariably comprising eight presacral vertebrae, a single sacral vertebra and, postsacrally, the urostyle. To resolve this incongruity between life phases and to determine the precise metamorphic fate of supernumerary caudal vertebrae in megophryids, we examined metamorphic specimens from the genera Leptobrachella, Leptolalax, Ophryophryne and Megophrys. In all four, the caudal larval skeleton undergoes massive reduction, leaving only the coccyx and hypochord untouched. Caudal centra are apparently degraded by osteoclasts, which have not previously been implicated in vertebral remodelling during anuran metamorphosis. In Megophrys and Ophryophryne metamorphs, presacral centra also undergo resorption, consistent with an epichordal mode of centrum formation. The conservation of megophryid adult axial osteology in the face of extensive larval skeletal diversity reveals the role of metamorphosis in constraining anuran morphology.