Cranial musculature in the larva of the caecilian, <i>Ichthyophis kohtaoensis</i> (Lissamphibia: Gymnophiona)

Kleinteich, Thomas; Haas, Alexander

doi:10.1002/jmor.10503

Cited by 27 publications

(60 citation statements)

References 46 publications

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“…The branches of the trigeminal nerve traverse the muscle group but do not define its components. This hypothesis is advanced for anurans with the data presented here and from Luther (1914), Starrett (1968), and Haas (2001), for salamanders from Luther (1914), Carroll and Holmes (1980), Haas (2001), and Lubosch (1938), and in caecilians from Luther (1914) and Kleinteich and Haas (2007). The formulation of this plan for caecilians accepts Haas' (2001) interpretation that the caecilian m. levator mandibulae ''externus'' of Edgeworth (1935) and ''medius'' of Luther (1914) represent the posterior (articularis) component as seen in the other Lissamphibia.…”

Section: Hypothesis-organization Of Lissamphibian Mandibular Adductorssupporting

confidence: 53%

Cranial muscles of the anuransleiopelma hochstetteriandascaphus trueiand the homologies of the mandibular adductors in lissamphibia and other gnathostomes

Johnston

2011

Journal of Morphology

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The frogs Ascaphus truei and Leiopelma hochstetteri are members of the most basal lineages of extant anurans. Their cranial muscles have not been previously described in full and are investigated here by dissection. Comparison of these taxa is used to review a controversy regarding the homologies of the jaw adductor muscles in Lissamphibia, to place these homologies in a wider gnathostome context, and to define features that may be useful for cladistic analysis of Anura. A new muscle is defined in Ascaphus and is designated m. levator anguli oris. The differences noted between Ascaphus and Leiopelma are in the penetration of the jaw adductor muscles by the mandibular nerve (V3). In the traditional view of this anatomy, the paths of the trigeminal nerve branches define homologous muscles. This scheme results in major differences among frogs, salamanders, and caecilians. The alternative view is that the topology of origins, insertions, and fiber directions are defining features, and the nerves penetrate the muscle mass in a variable way. The results given here support the latter view. A new model is proposed for Lissamphibia, whereby the adductor posterior (levator articularis) is a separate entity, and the rest of the adductor mass is configured around it as a folded sheet. This hypothesis is examined in other gnathostomes, including coelacanth and lungfish, and a possible sequence for the evolution of the jaw muscles is demonstrated. In this system, the main jaw adductor in teleost fish is not considered homologous with that of tetrapods. This hypothesis is consistent with available data on the domain of expression of the homeobox gene engrailed 2, which has previously not been considered indicative of homology. Terminology is discussed, and "adductor mandibulae" is preferred to "levator mandibulae" to align with usage in other gnathostomes.

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Section: Hypothesis-organization Of Lissamphibian Mandibular Adductorssupporting

confidence: 53%

Cranial muscles of the anuransleiopelma hochstetteriandascaphus trueiand the homologies of the mandibular adductors in lissamphibia and other gnathostomes

Johnston

2011

Journal of Morphology

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“…In previous studies, we provided hypotheses on the homologies between cranial structures in amphibian larvae and inferred hypotheses on character transformations in the larval cranial musculature that can be tested for congruence in phylogenetic analyses. A terminology that is consistent with the hypotheses on the homologies between head muscles in the different amphibian groups has been proposed (Haas, ; Kleinteich and Haas, ). Here, we apply this terminology to compare the cranial musculature in larvae of salamander species within the Hynobiidae, Cryptobranchidae, and Dicamptodontidae.…”

Section: Introductionmentioning

confidence: 71%

“…The terms for cranial muscles in amphibian larvae are unfortunately not being used consistently in the literature and a large amount of synonyms has been introduced in the past. We carefully reviewed the terms for cranial muscles in amphibian larvae in previous studies from our group (Haas, ; Kleinteich and Haas, ) and suggested a terminology that reflects our hypotheses for the homologies among cranial muscles. Herein we build upon these previous studies and use the terminology suggested in Haas () for the nervus trigeminus (cranial nerve V) innervated muscles and in Kleinteich and Haas () for the remainder cranial muscles.…”

Section: Methodsmentioning

confidence: 99%

Anatomy, function, and evolution of jaw and hyobranchial muscles in cryptobranchoid salamander larvae

Kleinteich

Herzen

Beckmann

et al. 2013

Journal of Morphology

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Larval salamanders (Lissamphibia: Caudata) are known to be effective suction feeders in their aquatic environments, although they will eventually transform into terrestrial tongue feeding adults during metamorphosis. Early tetrapods may have had a similar biphasic life cycle and this makes larval salamanders a particularly interesting model to study the anatomy, function, development, and evolution of the feeding apparatus in terrestrial vertebrates. Here, we provide a description of the muscles that are involved in the feeding strike in salamander larvae of the Hynobiidae and compare them to larvae of the paedomorphic Cryptobranchidae. We provide a functional and evolutionary interpretation for the observed muscle characters. The cranial muscles in larvae from species of the Hynobiidae and Cryptobranchidae are generally very similar. Most notable are the differences in the presence of the m. hyomandibularis, a muscle that connects the hyobranchial apparatus with the lower jaw. We found this muscle only in Onychodactylus japonicus (Hynobiidae) but not in other hynobiid or cryptobranchid salamanders. Interestingly, the m. hyomandibularis in O. japonicus originates from the ceratobranchial I and not the ceratohyal, and thus exhibits what was previously assumed to be the derived condition. Finally, we applied a biomechanical model to simulate suction feeding in larval salamanders. We provide evidence that a flattened shape of the hyobranchial apparatus in its resting position is beneficial for a fast and successful suction feeding strike.

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“…levatores mandibulae group (figure 1). This group comprises three muscles in adult caecilians: m. levator mandibulae articularis; m. levator mandibulae internus; and m. levator mandibulae longus (Wiedersheim 1879;Luther 1914;Edgeworth 1935;Lawson 1965;Bemis et al 1983;Iordanski 1996;Wilkinson & Nussbaum 1997; a table of synonyms was presented by Kleinteich & Haas 2007). The EMA for single muscles in this group EMA LEV is calculated by…”

Section: Methodsmentioning

confidence: 99%

“…However, the studies of the cranial musculature in caecilians (Wiedersheim 1879;Luther 1914;Lawson 1965;Bemis et al 1983;Nussbaum 1983;Iordanski 1996;Wilkinson & Nussbaum 1997;Kleinteich & Haas 2007) show that the fibre orientation of the IHP in most caecilian species is oblique rather than purely anteroposterior; the muscle fibres run in the caudal and ventral directions. A second simplification in the previous model was to ignore the jaw-closing function of the mm.…”

Section: Introductionmentioning

confidence: 99%

Caecilian jaw-closing mechanics: integrating two muscle systems

Kleinteich

Haas

Summers

2008

J. R. Soc. Interface.

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Caecilians (Lissamphibia: Gymnophiona) are unique among vertebrates in having two sets of jaw-closing muscles, one on either side of the jaw joint. Using data from high-resolution X-ray radiation computed tomography scans, we modelled the effect of these two muscle groups (mm. levatores mandibulae and m. interhyoideus posterior) on bite force over a range of gape angles, employing a simplified lever arm mechanism that takes into account muscle crosssectional area and fibre angle. Measurements of lever arm lengths, muscle fibre orientations and physiological cross-sectional area of cranial muscles were available from three caecilian species: Ichthyophis cf. kohtaoensis; Siphonops annulatus; and Typhlonectes natans. The maximal gape of caecilians is restricted by a critical gape angle above which the mm. levatores mandibulae will open the jaw and destabilize the mandibular joint. The presence of destabilizing forces in the caecilian jaw mechanism may be compensated for by a mandibular joint in that the fossa is wrapped around the condyle to resist dislocation. The caecilian skull is streptostylic; the quadrate-squamosal complex moves with respect to the rest of the skull. This increases the leverage of the jaw-closing muscles. We also demonstrate that the unusual jaw joint requires streptostyly because there is a dorsolateral movement of the quadrate-squamosal complex when the jaw closes. The combination of the two jawclosing systems results in high bite forces over a wide range of gape angles, an important advantage for generalist feeders such as caecilians. The relative sizes and leverage mechanics of the two closing systems allow one to exert more force when the other has a poor mechanical advantage. This effect is seen in all three species we examined. In the aquatic T. natans, with its less well-roofed skull, there is a larger contribution of the mm. levatores mandibulae to total bite force than in the terrestrial I. cf. kohtaoensis and S. annulatus.

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Cranial musculature in the larva of the caecilian, Ichthyophis kohtaoensis (Lissamphibia: Gymnophiona)

Cited by 27 publications

References 46 publications

Cranial muscles of the anuransleiopelma hochstetteriandascaphus trueiand the homologies of the mandibular adductors in lissamphibia and other gnathostomes

Cranial muscles of the anuransleiopelma hochstetteriandascaphus trueiand the homologies of the mandibular adductors in lissamphibia and other gnathostomes

Anatomy, function, and evolution of jaw and hyobranchial muscles in cryptobranchoid salamander larvae

Caecilian jaw-closing mechanics: integrating two muscle systems

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