Chaetophractus vellerosus ( Gray, 1865 ), 1928

Carlini, Alfredo A., Soibelzon, Esteban & Glaz, Damián, 2016, Chaetophractusvellerosus (Cingulata: Dasypodidae), Mammalian Species 48 (937), pp. 73-82 : 74-79

Chaetophractus vellerosus ( Gray, 1865)

Screaming Hairy Armadillo

Cryptophractus brevirostris Fitzinger, 1860:385 , 395. Nomen nudum.

Dasypus vellerosus Gray, 1865:376 . Type locality “ Santa Cruz de la Sierra,” Santa Cruz, Bolivia.

Dasyphractus brevirostris Fitzinger, 1871:264 . Type locality “ Chili.” Possibly from northwestern Argentina (Cerqueira and Tribe 2008:41).

Chaetophractus vellerosus: Gray, 1873:19 . First use of current name combination.

[ Dasypus (Choetophractus) ] vellerosus: Trouessart, 1898:1146 . Name combination.

Dasypus vellerosus pannosus Thomas, 1902:244 . Type locality “Cruz del Eje,” Córdoba, Argentina.

[ Dasypus (Chaetophractus) vellerosus ] pannosus: Trouessart, 1905:820. Name combination.

Dasypus boliviensis Grandidier and Neveu-Lemaire, 1908:5 . Type locality “environs d’Uyuni ( Bolivie), à 3,600 mètresd’altitude,” Potosí, Bolivia; preoccupied by Tatusia boliviensis Gray, 1873 , a synonym of Dasypus novemcinctus Linnaeus, 1758 .

Dasypus villerosus Grandidier and Neveu-Lemaire, 1908:6 . Incorrect subsequent spelling of Dasypus vellerosus Gray, 1865 .

Dasypus vallerosus pannosus O. Thomas, 1902:221 . Incorrect subsequent spelling of Dasypus vellerosus Gray, 1865 .

Chaetophractus vellerosus pannosus: Yepes, 1928:500 . Name combination.

Chaetophractus vellerosus vellerosus: Yepes, 1928:500 . Name combination.

E [uphractus]. vellerosus: Krumbiegel, 1940:56 . Name combination.

Euphractus villosus desertorum Krumbiegel, 1940:61 . Type locality “San Carlos, Chaco,” Argentina.

CONTEXT AND CONTENT. Context as for genus. Commonly this species is cited as Chaetophractus vellerosus ( Gray, 1865) Yepes 1928 , crediting Yepes with the 1st use of the current name combination; however, Gray (1873:19) himself proposed the current combination. There are 2 subspecies recognized ( Gardner 2005):

C. v. vellerosus ( Gray, 1865) . See above.

C. v. pannosus (O. Thomas, 1902) . See above.

DIAGNOSIS

Chaetophractus vellerosus ( Fig. 1 ) is the smallest of the Euphractini (head-and-body length <255 mm — Wetzel et al. 1985b, 2007), though its size is close to that of the pichi, Zaedyus pichiy (Superina and Abba 2015) ; the dorsum of C. vellerosus is variegated brown and pale tan ( Wetzel 1985a) and has the greatest hairiness (both ventral and dorsal) among the living Euphractini ( Wetzel 1985b) . Ears are proportionally much longer than those of the pichi (> 20 mm versus <20 mm in the pichi—Superina and Abba 2015) and the big hairy armadillo, C. villosus , and similar to those of the Andean hairy armadillo, C. nationi ( Anderson 1997) .

The cephalic shield ( Fig. 2 ) is more isodiametric (width:length = 0.919, based on measurements taken from 17 museum specimens of mixed sexes) than in the pichi (width:length = 0.77; Superina and Abba 2015) and not as wide as in C. villosus ( Wetzel 1985b:29) . The cephalic shield is formed by osteoderms that are not as smooth as those of the pichi, though scarcely sculpted (mainly at the postocular region), unlike C. villosus , which has the entire shield, ornamented. The posterior margin is flattened, not reflecting individual curves of each marginal osteoderm ( Wetzel 1985b). There are 2 well-developed nuchal strips ( Fig. 2 ), the posterior one with 25 to 31 osteoderms.

The scapular shield is relatively small, with no more than 4 rows of osteoderms in the middle plane (more numerous toward the margins), unlike C. villosus that has generally 5 or 6. Six to 9 mobile strips at sagittal line (usually 7 or 8; Fig. 2 ), sometimes the most posterior is attached to central part of pelvic shield; 4th mobile strip with 32 to 41 osteoderms (see Abba 2008). The osteoderms of the mobile strips present 3 distinct longitudinal zones (1 central zone and 2 lateral zones; see Fig. 2 ). The lateral zones are divided into small peripheral figures (4 or 5 in number), the most posterior of which is the largest; small foramina are present in the area where the posterior apex of each small figure intersects the separation line between lateral and central zones (see Krmpotic et al. 2009 for foramina interpretation). The posterior border of the osteoderms is rather straight and bears numerous pi1iferous foramina; there is a relatively short area shaped like a shallow transversal groove, which appears rough and longitudinally striated due to numerous canaliculi opening on its external surface. This groove separates the articulation zone from the posterior part of the osteoderm (see Soibelzon et al. 2006).

Pelvic shield ( Fig. 2 ) is more extended than scapular shield, with 9–10 rows of osteoderms in middle plane, which is more than twice the length of scapular shield (Cabrera and Yepes 1940). Pelvic shield has 1 or 2 sagittal osteoderms with larger holes (compared with size of the normal foramina) corresponding to edoneous glands in the central area of pelvic carapace (the pichi has none). Marginal osteoderms of dorsal carapace are not as sharp as those of the pichi and C. villosus . Tail is longer than one-half the length of head and body and proportionally longer than that of C. nationi , C. villosus , and the pichi (Cabrera and Yepes 1940).

The skull of C. vellerosus ( Fig. 3 ) is similar to that of the pichi. The rostrum of C. vellerosus is not as elongated and generally without the slight frontal depression of the pichi. Zygomatic arch is short, as in other Euphractini , and according to Wetzel (1985b), height of jugal is not uniform as in the pichi (though not all specimens of pichi clearly show this character). Teeth are always euhypsodont, and dental formula is 9/10 (some specimens have 9/9), with 1 tooth in the premaxillary, as in C. villosus but different from the pichi which has 8/9 and no premaxillary teeth (Superina and Abba 2015).

The 2 proposed subspecies ( C. v. vellerosus and C. v. pannosus ) are differentiated essentially by the amount and distribution of hair on the body ( Yepes 1928). In C. v. vellerosus , hair is very abundant on the carapace and ventral parts, with numerous long hairs (> 36 mm). Conversely, in C. v. pannosus , hair covering the body is less dense and there are fewer long hairs ( Yepes 1928). Based on limited observations, it has been suggested that at least part of the specimens referred to as C. nationi may correspond to a 3rd subspecies of C. vellerosus that occurs at high altitude ( Wetzel 1985a, 1985b).

GENERAL CHARACTERS

Chaetophractus vellerosus is a small dasypodid. Average external and cranial measurements (mm, parenthetical range; taken by authors) for 12 males and 11 females, respectively, from Pipinas (35°34′S, 57°16′W; see Fig. 4 ) were: total length, 357.9 (310–399), 355.4 (322–401); length of head and body, 245.1 (210– 284), 242.7 (214–271); tail length, 112.8 (100–128), 112.6 (99– 133); hind foot length, 49.2 (40–53), 48.9 (45–55); and ear length, 30.4 (25–33), 29.8 (22–32). Mean body mass (g) of 53 adult males and 59 adult females, all from the same location (Magdalena, 1 from Bolivia (the holotype), and 4 from Paraguay ( Wetzel 1985b) were: length of head and body, 230.1 (221.8–238.4, 19); tail length, 104.1 (95.1–113.1, 19); hind foot length, 47.0 (41.5–52.5, 16); ear length, 30.8 (29–32.6, 14); condylonasal length, 62.6 (60.8–64.4, 20); and width:length ratio of head shield, 0.9 (0.86–0.94, 17).

Hair is tan and comparatively dense all over the body; pinnae long, extending back to the 1st fused row of osteoderms on scapular shield ( Gardner 2007). The limbs and belly are covered with whitish or light brown hairs ( Nowak 1999).

Farmers generally believe that C. vellerosus is easily captured because it is not a good runner, but based on our observations, capturing it is not easy on irregular ground where C. vellerosus is able to change direction suddenly, or when numerous burrows are present, and it is able to dart into inactive burrows; C. vellerosus is a quick and skillful digger. If pulled from the burrow by its tail, it will hold on with its claws and extend its carapace against the burrow wall, increasing resistance by using the serrated margin of the carapace against the wall. When caught, its screams loudly (like C. nationi ) similar to a baby’s crying. This protest call resulted in the common name “piche llorón” (screaming hairy armadillo) and permits its escape from predators ( Wetzel 1982).

Buenos Aires Province, Argentina), was 771.51 (± 134.155 SD) and 802.37 (± 122.564 SD —Abba et al. 2011), respectively. Mean measurements (mm, with parenthetical ranges) of 76 males and 71 females, respectively, from northwestern Argentina ( Greegor 1974) were: total length, 376 (328–400), 368 (265–419); tail length, 114 (84–131), 112 (77–138); hind foot length, 49 (44–53), 48 (31–56); ear length, 28 (22–31), 27 (22–31); and body mass (g), 860 (543–1,329), 814 (257–1,126). Measurements (mm) of a single female from Roboré, Bolivia (18°20′S, 59°44′W — Anderson 1997) were: total length, 440; tail length, 152; hind foot length, 72; ear length, 30; and body mass (g), 950. Mean measurements (mm, with parenthetical ranges, n) for 15 specimens from Argentina,

DISTRIBUTION

Chaetophractus vellerosus occurs from the Bolivian Chaco, southeastern Bolivia, near the locality of Santa Cruz de la Sierra ( Anderson 1997; Gardner 2007), Puna Boliviana ( Wetzel 1985b), and Paraguayan Chaco, western Paraguay ( Crespo 1974), southwards in the Argentine provinces of Jujuy, Salta, most of Tucumán, Catamarca, north of La Rioja, Córdoba, San Luis, and east of Santa Fe ( Yepes 1928, 1929; Cabrera 1958; Wetzel 1982, 1985b; Redford and Eisenberg 1992), reaching the provinces of Mendoza and La Pampa, and the southeastern portion of Buenos Aires Province ( Crespo 1974; Wetzel 1982; Carlini and Vizcaíno 1987; Redford and Eisenberg 1992; Abba et al. 2011, 2016). C. v. vellerosus is distributed in Bolivia and the highlands of North Western Argentina, and C. v. pannosus , in lower areas of northwest Argentina, reaching the easternmost pampas ( Yepes 1928, 1929; Cabrera 1958; Fig. 4 ). This disjunct distribution in Argentina has been explained as a relic of a more extensive paleo distribution that comprised the current territory of Buenos Aires Province during the late Pleistocene and part of the Holocene (Carlini and Vizcaíno 1987) and is in concordance with the recent phylogeographic studies which indicate that the ancestral haplotype of the species is in the Tucumán province and the derived haplotype in the Samborombón Bay ( Poljak 2009). Recent discoveries in ensenadan sediments (Early to Middle Pleistocene) of southeastern Buenos Aires have allowed extension of also the temporal distribution of this species (see “Fossil Record”). The records in the Puna de Tarapacá, Chile, by Gardner (2005, 2007), probably correspond to C. nationi (Abba and Superina 2010a, 2010b).

In the province of Buenos Aires ( Argentina), C. vellerosus has a fragmented distribution, as several specimens have been recorded in the coastal area from 34° to 36° of South latitude (ca. 170 km) in the Samborombón Bay and 70 km to the north ( Crespo 1974; Carlini and Vizcaíno 1987; Soibelzon et al. 2007; Abba and Vizcaíno 2011; Abba et al. 2016). Soil conditions within all areas of occurrence of C. vellerosus are similar, though mean annual precipitation across the distribution varies. In central and northwestern regions of Argentina, rainfall is between 200 and 600 mm and in the eastern portion of Buenos Aires Province, between 1,000 and 1,200 mm ( Fig. 4 ). The elevational distribution is wide, from sea level up to 4,000 m (perhaps more, see Crespo 1944).

Wetzel (1985a, 1985b) recorded C. vellerosus in the Argentine provinces of Río Negro and Santa Cruz based only on 2 specimens from the collection of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (MuseoArgentino de Ciencias Naturales [MACN] 31.2, a skull of Arroyo Pilcaniyeu 41°S, 70°W, MACN 29.899, a carapace of Santa Cruz Province 46°S, 52°S), collected in 1929 by Dr. A. Artayeta and L. Parodi, respectively. These records should be used with caution because there are irregularities in the catalog, and specimens and provenance may be confused with those of the pichi, which certainly inhabits those localities.

FOSSIL RECORD

Despite the fossil record of the genus Chaetophractus beginning in the Pliocene (Chapadmalalan Age/Stage), the species C. vellerosus is recorded in numerous provinces of Argentina: Buenos Aires during Ensenadan Age in “Punta Hermengo” (Lower to Middle Pleistocene— Soibelzon et al. 2006, 2010); La Pampa in the archaeological site “Tapera Moreira” (38°33′S, 65°33′W —Berón and Baffi 2003); Santa Fe in the archaeological site “La Lechuza” (29°54′19.9″S, 59°55′22.2″W — Cornero et al. 2007); Córdoba in the archaeological sites “Las Chacras or C.Pun.39” (31°03′S, 64°31′W), Puesto La Esquina 1 (PE1, 31°09′S, 64°37′W), Arroyo Talainín 2 (31°18′S, 65°12′W), and TalaHuasi (31°27′S, 64°38′W, Department Punilla— Soibelzon et al. 2013); Mendoza in the archaeological site “Agua de la Cueva” (32°37′S, 69°04″W— Gil et al. 2011). Additionally, Vizcaíno et al. (1995) mentioned its presence in the Late Pleistocene of Catamarca, but without precise geographic location and collection number.

FORM AND FUNCTION

The head region of spermatozoa of Chaetophractus vellerosus is very large and similar to that of C. villosus , the pichi, and Euphractus sexcinctus , the 6-banded armadillo ( Cetica et al. 1997, 1998; Cetica and Merani 2008). In frontal view it is long and wide (14.47 µ ± 0.4 SD and 12.68 µ ± 0.4 SD, respectively), in lateral view it is extremely thin, except at the base near the insertion point of the tail; consequently, the sperm head is transparent when observed through a contrast microscope. The sperm head is paddle-like in outline and posteriorly truncated. In lateral view, spermatozoids are spoon-like and commonly piled up. The acrosome covers about 70.2% of the head length and the postacrosomal region is relatively short. Staining with DAPI (4′6-diamidino-2-phenylindole, 0.2 μg/ml in McIlvaine’s buffer pH 6.8) showed the nucleus (and its chromatin) extending homogeneously along the head of the spermatozoid ( Cetica et al. 1997). The nuclear volume was estimated as 16.61 µ 3 and the mean nuclear thickness is 0.11 ± 0.06 µ SD. The acrosomal narrowing covers a large portion of the nucleus and is not significantly thicker than the spermatic maximum thickness ( Cetica et al. 1997). The tail length and the total sperm length are similar to those of spermatozoids of most Eutheria ( Cetica et al. 1997).

With respect to kidney function, C. vellerosus has a relative medullary thickness (RMT) of 7.5 ± 0.5 SD, a value that is above the normal range of values expected for desert mammals of its size (RMT = 7.1 for 850 g weight— Greegor 1975). This indicates extreme ability to concentrate urine and consequently conserve water ( McNab 1980; Greegor 1985). Greegor (1975) demonstrated the ability of C. vellerosus to extract and retain water from food in a comparison of it with a species of similar size, 9-banded armadillo (RMT = 4.9 ± 0.4 SD). When both species were fed a diet with reduced water content (but given free access to water), C. vellerosus lost only 2% of its body weight; in contrast, the 9-banded armadillo lost 15% after 11 days on the diet. This outcome suggests that C. vellerosus is not dependent on succulent food, which is scarce several months out of the year in desert or semidesert zones where it is mainly distributed ( Greegor 1975).

Concerning body temperature, C. vellerosus has the typical pattern of armadillos, maintaining a low body temperature (34.4°C) independently of ambient temperature ( McNab 1980), but lower body temperatures in cold seasons than in warm seasons have been reported (Abba et al. 2011). Greegor (1985), in turn, reported that the body temperature of 2 specimens studied inside their own burrows dropped around 5.4°C and 6°C in 1 h, although the temperature of the burrows decreased less than these values. Basal metabolic rate is low (47% of the expected value for an animal of 1,100 g) and the minimal thermal conductance is high (117%). Consequently, the lower limit of thermoneutrality is relatively high (30°C). This kind of control of body temperature may explain why C. vellerosus avoids thermal extremes by concentrating its activity in the hottest hours of the day during the winter, and switching to diurnal activity in summer. Low metabolic rates are important in the setting of long gestation periods, low growth rates, long periods of parental care, and reduced number of offspring ( McNab 1980, 1985). In winter, both females and males increase their body weight by more than 10%, developing a subcutaneous fat layer 1 to 2 cm thick, which may be even thicker in animals in captivity (Redford and Eisenberg 1992).

ONTOGENY AND REPRODUCTION

As most dasypodids (except members of the genus Dasypus ), Chaetophractus vellerosus has 1 or 2 large young per litter, commonly once a year. As in C. nationi , C. villosus , and the pichi, females have a pair of pectoral mammae ( Nowak 1999). A captive mother weighing 760 g in the Zoo of La Plata gave birth to a pair of young, 44.0 and 42.0 g each, born in November 1998. Mean body mass for 5 young females and males was 45.0 and 48.0 g, respectively (Abba et al. 2011). Young are born with eyes closed and eyes do not open until young are 7–10 days of age. The carapace is not ossified, and cornified scales are not developed, but young already display the definitive general structure; claws are poorly keratinized and pilosity of the body is not developed yet ( Krmpotic et al. 2012).

The longevity of this species is unknown, but it is supposedly not much different from that of other euphractines. A specimen of C. villosus in captivity lived 15 years and 7 months ( Flower 1931).

Chaetophractus vellerosus has a seasonal reproductive pattern. This is supported by the results of Luaces et al. (2011) who found significant correlation between dry fecal and plasma progesterone concentrations. Toward the end of winter and beginning of spring, one of us (DG) commonly observed groups of 2– 5 males tirelessly pursuing a female between midday and early afternoon (1200 to 1600 h). During tracking studies, numerous attempts of copulation, in which a single male covered the female by holding itself to the female’s back with his forelimbs, were observed.

Figures

Fig. 1.—An adult of Chaetophractus vellerosus from Pipinas, Buenos Aires Province, Argentina. Photo by Esteban Soibelzon used with permission.

Fig. 2.—Dermic carapace of Chaetophractus vellerosus. From top to bottom: cephalic shield, nucal strips, and scapular shield, movable bands (just detail of some osteoderms of them), and pelvic shield. Graphic scale = 1cm. Greatest length of the cephalic shield is 58.1mm.

Fig. 3.—Dorsal, ventral, and lateral views of the skull, and lateral and dorsal view of the mandible of Chaetophractus vellerosus. Greatest length of skull is 65.6mm.

Fig. 4.—Geographic distribution of Chaetophractus vellerosus. Extended light gray shading indicates main distribution area; small black shading indicates relictual area in Buenos Aires Province (including Pipinas locality), Argentina. Black dots indicate archaeological sites: 1) “Tapera Moreira,” La Pampa Province; 2) “La Lechuza,” Santa Fe Province; 3) 4 Late Holocene sites in Córdoba Province; 4) “Agua de la Cueva,” Mendoza Province. Black square indicates fossil record at Punta Hermengo, Miramar, Buenos Aires.