MORPHOLOGICAL DIVERSITY OF FACIAL VIBRISSAE IN Chaetophractus vellerosus (MAMMALIA, XENARTHRA, DASYPODIDAE) AND DIFFERENTIAL MECHANOPERCEPTION

KRMPOTIC, CECILIA MARIANA; ANDRÉS LAUBE, PEDRO FERNANDO; BARBEITO, CLAUDIO GUSTAVO; POMBO, MARÍA TERESA; SCARANO, ALEJO CARLOS; LOZA, CLEOPATRA MARA; CARLINI, ALFREDO ARMANDO

ZOOLOGY

ELSEVIER GMBH

Año: 2020 vol. 140

0944-2006

Vibrissae are specialized and complex mechanoreceptor organs present in the skin of most mammals that respondto a diverse mechanical stimuli (e.g. tension, pressure, movement, vibrations) and provide information ondistance to the object, its location/orientation, and general characteristics of its surface; also, it may play diverseroles during food acquisition and attacking potential prey. There are scarce papers on the vibrissae of armadillos,only considering their presence/absence and distribution, but no histological analyses have been made. The goalof our contribution is to perform a histological study of the head vibrissae of Chaetophractus vellerosus, identifytheir morphological features, the tissues that form them, interpret their possible functions, and attempt to linkthe characteristics with ecological aspects of this species like its digging habits. Our results suggest thatChaetophractus vellerosus possesses two types of vibrissae: macro- and micro-vibrissae. Both types are similar ingross morphology, characterized mainly by an absence of annular sinus and ringwulst, but having a trabecularsinus that extends along the entire length of the follicle; these features might be linked to a reduction of itssensory capacity. Unlike other mammals, the macro-vibrissae are in the genal, anterobital and intermandibularregions, while micro-vibrissae are distributed in the superior labial and mental regions. In addition to sizedifferences, the macro-vibrissae possess intrinsic muscles composed of smooth muscular fibers. The genal macrovibrissaeare very close to each other, with smooth muscle fibers connecting the capsules of adjacent ones(intrinsic muscles). Those from the superior labial and mental (micro-vibrissae), show bundles of striated muscleinserted on their capsules. These muscle fibers would be part of the facial musculature and could be consideredas extrinsic muscles. The mobility of these two types of vibrissae must certainly be different, given that therespective muscles (intrinsic and extrinsic) have different origins and innervation. The presence of two types ofvibrissae might indicate that these mechanoreceptors have differential perception capacities that would probablybe complementary, thus providing more precise information about the environment. The presence ofmacro-vibrissae in the genal, anteorbital and intermandibular zone would be directly related to the life habits ofChaetophractus vellerosus.