Giant Chacoan Peccary (Catagonus wagneri)

Order: Artiodactyla

Family: Tayassuidae

1) General zoological data of species

Wetzel and Crespo (1975) formally first described this third species of peccary. It is restricted to the Chaco region of Paraguay, Northern Argentina and Eastern Bolivia (Taber, 1993). Contrary to the other two species of peccary (collared peccary and white-lipped peccary), this animal forms small family groups of up to eleven individuals. It has become very rare in the "Chaco Boreal" and was feared of becoming extinct. It was thus declared a "CITES I" species and hunting bans were introduced. It has become my favorite animal. With the Zoological Society of San Diego I formed a breeding colony of these animals near the center of the Paraguayan Chaco, in Toledo. Hundreds of animals were bred, released, and some were exported to Phoenix, Arizona, USA. Offspring of that colony went to the San Diego Zoo, and offspring bred there went to zoos in St. Louis and Los Angeles. The species is now sparsely distributed in the same habitat, which is, however, shrinking because of an expanding agriculture (Handen et al., 1994). Oversight is now accomplished by the Pigs and Peccaries" group of IUCN (Oliver, 1993) and a SSP by AZA.

Adult female taguá weigh around 35 kg. They have longer legs and a much larger head than the collared peccary with which the animal is otherwise similar. Detailed anatomical descriptions have been published by Olrog et al. (1976) and by Wetzel (1977), the original discoverer of this species.

Family Group of taguá at Toledo, Paraguay.

2) General gestational data

A pregnant female was reported to have weighed 43.5 kg (Mayer & Wetzel, 1986). Litters vary from 2-4 (average 2.72, triplets being most common). Neonates weigh around 400-600 g. The length of gestation has been given as 184 days (Brooks, 1992) but it may be shorter, as it is in the other two peccary species. The mesonephroi of fetuses are unusually large, and fetal as well as adult ovaries contain a huge central "interstitial gland" whose products are unknown. The placental weight has not yet been determined.

Parents and two young at San Diego Zoo, 1999.

3) Implantation

The diffuse epithelio-chorial placenta occupies the uterus diffusely. It has "ripples" on its surface and possesses a large allantoic sac, a relatively short umbilical cord, and a small amnionic cavity. There is no trophoblastic invasion of the uterus. The placenta is similar to those of Suidae and other Tayassuidae (Macdonald & Bosma, 1985). Most recently, Miglino et al. (2001) have studied the placentas of the other two species of peccaries. They used very fresh material that was collected under optimal condition. Santos et al. (2006) have published excellent details of the placentas in 13 collared peccaries and 3 white-lipped peccaries, in addition to superior electronmicroscopic studies. As in taguá, their placentas are diffuse, epitheliochorial organs without trophoblastic invasion.

Implantation is very superficial and short, simple villi develop that attach directly to the superficial endometrium. The cord insertion is mesometrial.

Delivered term taguá placenta, diffuse and very thin.

4) General characteristic of placenta

The peccary has a diffuse epithelio-chorial placenta with large allantoic sac, which has a lining of columnar epithelium. In a specimen of triplets, I found the fetuses occupied both uterine horns; the placentation was trichorionic and there were three corpora lutea present in the maternal ovary. The allantoic sac has abundant fine blood vessels.

First trimester triplet in its placenta whose external surface is rippled by the villi.

Delivered term placental histology. Amnion at left and is attached to the chorion. Villi at right.

5) Details of barrier structure

The cuboidal chorionic epithelium directly apposes the endometrial epithelium and beneath which there is a large capillary network. PAS-positive secretion is present in the endometrial glands, but not within the epithelial cells. In the trophoblast are subnuclear PAS-positive vacuoles, similar to what has been described of Suidae (Macdonald & Bosma, 1985). There is no true syncytium.

First trimester taguá implantation. The uterus is left, placenta right.

Taguá placenta of stillbirth, vacuolated trophoblast.

Higher magnification of villous surface.

Trophoblast with PAS+ vacuoles.

6) Umbilical cord

In one full-term placenta with fetus, the umbilical cord was 4.5 cm long, had no spirals and contained two arteries, one vein, and a large allantoic duct. The duct was accompanied by numerous small blood vessels. The surface of the cord had no plaques or caruncles, but squamous metaplasia was present.

7) Uteroplacental circulation

This has not yet been described.

8) Extraplacental membranes

There are no separate "free" membranes in this entirely diffuse placenta. There is also no decidualization of the endometrium. With early gestations, the amnion is closely applied to the fetal surface, with only a small amount of fluid (Benirschke, 2000). The allantoic epithelium is cylindrical to cuboidal and there is an underlying capillary network.

9) Trophoblast external to barrier

There is no trophoblastic infiltration below the uterine epithelium.

10) Endometrium

There is no decidualization.

11) Various features

Subplacenta and metrial glands are not present.

12) Endocrinology

Adult and fetal ovaries contain large "interstitial glands" with a distinct endocrine appearance. They are in the center, beneath the cortical tissue. Their secretory product is unknown. Placental hormones have not been described. The adult testes contain a large number of interstitial cells.

Two ovaries of an adult, nonpregnant female. The central "interstitial gland" is labeled I, the thin cortex contains the ova.

Microscopic appearance of ovarian cortex (left) and interstitial gland (right).

13) Genetics

The taguá has 20 chromosomes, in contrast to the other two species. They have, respectively, 26 and 30 elements. In the genetic study of mtDNA, Theimer and Keim (1988) suggested that the invasion of peccary ancestors to South America in the Pliocene led to their segregation into separate clades (see also Marshall, 1988). Although these species all occur sympatrically in the Chaco, hybridization with the other species has not been recorded.

The putative evolutionary chromosomal rearrangements have been described for the three tayassuid species, including banding homologies (Benirschke et al., 1985; Benirschke & Kumamoto, 1989). The evolution of tayassuids has been considered in some detail by Wetzel (1977) and it was also the topic of Wallace (1988). A studbook is being maintained of the captive population.

In a recent cytogenetic study by Bosma et al. (2004), considerable chromosomal differences were found in the finer details of chromosome morphology between the collared and white-lipped peccaries. It contrasts with the more conservative arrangement of the suid chromosome morphology. Possible explanations were speculated upon and await further study.

Gongora & Moran (2005) have further examined nuclear and mitochondrial genes of all three species. They found greater mitochondrial gene divergence in collared peccaries than among the other two species, which are more closely related to each other than to collared peccaries. In addition, these authors reconsidered the question as to whether divergence originated before or after invasion of peccaries into South America after the landbridge was established. But final resolution of this question still awaits additional specimen study.

14) Immunology

There have been no reported studies.

15) Pathological features

The neonatal mortality is high in captive situations, but is it unknown for animals in the wild. Inadequate nutrition, sand imbibition, and pneumonia are the principal causes. Parasitism is very low in wild specimens (microfilaria, Balantidium sp.) and consists mostly of ectoparasites (Amblyoma sp.). I have seen one case of an apparently viral pneumonia that closely resembled Jaagsiekte of ruminants. A questionable spontaneous intestinal perforation has been observed. Tooth abnormalities and traumatic lesions occur, and much inhaled dust is found in adult animals' lungs. A partial posterior duplication suggested that conjoined twinning, perhaps monozygotic twinning, occurs. Placental infections have not been observed. Infections with Chlamydia psittaci was seen in a zoo because of the exposure to adjacent other artiodactyl animals that harbored the agent.

Older taguá often suffer chronic renal disease with renal and bladder calculi. They are comprised of oxalates. This is probably attributable to the preferred diet of cactus (Opuntia sp.). This putative relation to diet is in urgent need of being proven. Occasionally, taguá have had infections in the large scent glands located in the central portion of their dorsal sacral region. Much oily fluid can be secreted from this gland; the glandular secretions of the three species also have very different odors. It is of interest to learn what the fetal/maternal ovarian interstitial cell produces. Studies by incubating this tissue are needed.

16) Physiological data

No studies have been reported.

17) Other resources

Cell strains of many specimens are contained in the "Frozen Zoo" of "CRES" at the San Diego Zoo.

18) Other features of interest

The similarity of placentation to that of Suidae is striking. Please see the chapter on "Red River Hog". An extensive bibliography on peccaries can be downloaded from a section of CRES at the web site of the San Diego Zoo.

The neonatal uterus and appendages are shown here because of the rarity of the specimen. Note the very long vag