División Herpetología, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" - CONICET, Av. Ángel Gallardo 470, Buenos Aires, C1405DJR, Argentina.
Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina.
Cladistics. 2021 Oct;37(5):489-517. doi: 10.1111/cla.12451. Epub 2021 Feb 20.
The most ventral muscles of the head (the mm. submentalis, intermandibularis, and interhyoideus) provide support to the gular region and lift the buccal floor during ventilation and feeding. These muscles show limited variation in most gnathostomes, but in Anura they exhibit a surprising diversity. The few studies that have explored this character system highlighted its potential as a source of phylogenetic information. In this paper we explored the diversity of this character system studying specimens of 567 anuran species and reviewing published data to cover a total of 1321 species, belonging to 53 of the 54 currently recognized anuran families, as well as caudates and caecilians. We defined 27 discrete characters including the number of muscle bellies, supplementary layers, hypertrophy and diversity of elastic fibres, and pigmentation, among others, and optimized them on a comprehensive phylogenetic hypothesis. We recognized 223 unambiguously optimized synapomorphies for numerous clades on different scales, including three for Anura and many for suprafamiliar clades with poor phenotypic support. Finally, we discussed the evolution of this highly diverse character system, including homology, development, and its functional role in vocalization and feeding. Interestingly, the striking levels of variation in some structures contrast with the amount of phylogenetic inertia, allowing us to recognize several general patterns. Supplementary elements of the m. intermandibularis evolved first as broad layers occuring in more than half of extant anuran species and then concentrated forming discreet bellies in several clades. The anterior portion of the gular region is not sexually dimorphic, and is likely related to ventilation and tongue protraction. Conversely, the diversity of the m. interhyoideus is strongly linked to vocal sacs, which are present only in adult males, suggesting the presence of two independent modules.
头部最腹侧的肌肉（颏舌肌、下颌间肌和舌骨下肌）为颈区提供支撑，并在呼吸和进食时提起颊底。这些肌肉在大多数有颌类中变化有限，但在蛙类中表现出惊人的多样性。少数探索这个特征系统的研究强调了它作为系统发育信息来源的潜力。在本文中，我们通过研究 567 种蛙类标本并回顾已发表的数据来探索这个特征系统的多样性，共涵盖了 1321 种蛙类，隶属于 54 种目前公认的蛙类科，以及有尾目和蚓螈目。我们定义了 27 个离散特征，包括肌腹数量、补充层、肥大和弹性纤维多样性以及色素沉着等，并在一个综合的系统发育假说上对它们进行了优化。我们为许多不同规模的类群识别了 223 个明确的优化同源特征，包括 3 个蛙类类群和许多具有较差表型支持的超科类群。最后，我们讨论了这个高度多样化的特征系统的进化，包括同源性、发育以及其在发声和进食中的功能作用。有趣的是，一些结构的惊人变异水平与系统发育惰性的程度形成对比，使我们能够识别出几个一般模式。下颌间肌的补充成分首先进化为广泛的层，存在于超过一半的现生蛙类中，然后在几个类群中集中形成离散的肌腹。颈区的前部没有性别二态性，可能与呼吸和舌伸出有关。相反，舌骨下肌的多样性与声囊强烈相关，声囊仅存在于成年雄性中，这表明存在两个独立的模块。
