Zherebtsova O.V. 2016. Comparative analysis of the subcutaneous musculature in some hystricomorph rodents (Rodentia: Hystricomorpha) // Russian J. Theriol. Vol.15. No.2: 159–170 [in English].
Olga V. Zherebtsova [firstname.lastname@example.org], Zoological Institute of the Russian Academy of Sciences, Universitetskaya nab. 1, Saint Petersburg 199034, Russia.
ABSTRACT. The structure of the subcutaneous musculature (m. cutaneus trunci) in three species of hystricomorph rodents (Hystricomorpha): Dasyprocta leporina (Linnaeus, 1766), Chinchilla lanigera Bennett, 1829, and Octodon degus (Molina, 1782), was studied. The members of two other suborders of Rodentia, Rattus norvegicus (Berkenhout, 1769) (suborder Myomorpha) and Spermophilus citellus (Linnaeus, 1766) (suborder Sciuromorpha), were also included in the morphological analysis for comparative purposes. In these two forms, the m. cutaneus trunci is more simple and formed by a single muscular layer, terminating on the medial side of the humerus (medial head). This structure of the subcutaneous muscle is usually considered as more primitive, and probably close to its initial state which is characteristic of ancestral forms of Rodentia. In all hystricomorphs studied, a considerable differentiation and complication of the subcutaneous muscle is observed. In this case, a lateral head of the m. cutaneus trunci, inserting on the lateral aspect of the forelimb, is developed. The appearance of the pars thoracoabdominalis in the structure of the subcutaneous muscle is also a specific feature of the hystricomorph rodents. At the same time, in D. leporina and C. lanigera, a medial head of the m. cutaneus trunci is still well expressed, but in O. degus, it is almost lost. It can be assumed that the progressive development and complication of the subcutaneous muscle in the evolution of hystricomorphs was largely conditioned by the requirement to improve their locomotor functions during a broad adaptive radiation of this group.
KEY WORDS: Dasyprocta, Chinchilla, Octodon, Rattus, Spermophilus, m. cutaneus trunci, subcutaneous musculature.