Perrier's sifaka

Perrier's sifaka (Propithecus perrieri) is a lemur endemic to Madagascar. It was formerly considered to be a subspecies of diademed sifaka It has a very small range in northeastern Madagascar where its habitat is dry deciduous or semihumid forest. Part of its range is in protected areas. It is an almost entirely black sifaka and measures about 90 cm (35 in), half of which is a bushy tail. Females are slightly larger than males. It moves in small family groups through the canopy feeding on fruit, leaves, flowers, buds, and seeds. Groups have territories around one hectare and vocalise with each other. The main threats faced by this sifaka are habitat destruction and fragmentation due to slash-and-burn agriculture, charcoal gathering, and logging. The International Union for Conservation of Nature has rated its conservation status as "critically endangered".

Etymology Perrier's sifaka was named in honor of Henri Perrier de La Bâthie by Louis Lavauden in 1931. The term "sifaka" is derivative of the terrestrial alarm vocalization produced by species of western sifakas belonging to the Propithecus verreauxi group. Because Perrier's sifaka belongs to the eastern (P. diadema) group, it does not produce such a vocalization. The Antankarana people refer to the species as radjako, rajako, jakoe, or jakoey in honor of a legendary hero of the same name from whom they believe Perrier's sifakas are descended. An alternative narrative states that Radjako was a man who was hit with a spoon by his wife, which transformed him into a Perrier's sifaka. Elsewhere in Madagascar, Radjako appears in similar etiological myths for other lemur species, including the ring-tailed lemur and the indri. Radjako was borrowed into French as jacquot as a derogatory term for lemurs. Derivations of this term may be found in Bourbonnais Creole and Comorian languages. Perrier's sifaka is also known as ankomba joby, which is Malagasy for "black lemur." This term can also refer to the male blue-eyed black lemur. Ankomba is a derivation of the Swahili word komba, which means galago.

Taxonomy Perrier's sifaka belongs to the P. diadema group of eastern sifakas within the Propithecus genus. Like all eastern sifakas except for Milne-Edwards's sifaka (P. edwardsi), it has a somatic number of 2n = 42. 18 autosomnal chromosomes are metacentric, 14 are submetacentric, and eight are acrocentric. The X chromosome is metacentric, and the Y chromosome is acrocentric. Perrier's sifaka could have previously had two additional acrocentric chromosomes that underwent a Robertsonian translocation, resulting in a metacentric chromosome. Perrier's sifaka and the silky sifaka (P. candidus) form a clade to the exclusion of the diademed sifaka (P. diadema) and Milne-Edwards's sifaka.

Changes in taxonomy Like other eastern sifakas, Perrier's sifaka was previously considered to be a subspecies of a broader P. diadema species that included the silky sifaka, the diademed sifaka, and Milne-Edwards's sifaka. The consolidation of the eastern lemurs into a single species was widely accepted following the publication of Ernst Schwarz's 1931 revision of lemur taxonomy. A fifth subspecies known as the black sifaka (P. d. holomelas) was recognized prior to the 1980s, but was considered synonymous with Milne-Edwards's sifaka after Ian Tattersall found the two subspecies to be sympatric. The broad P. diadema species classification was largely abandoned due to mitochondrial evidence found by Mireya Mayor et al. which indicated that the genetic distance between the four subspecies met the criteria for speciation according to the phylogenetic species concept.

Description Perrier's sifaka is the smallest eastern sifaka. It has a body length of 85–92 cm, of which 42–46 cm are tail. It weighs 3.7–6.0 kg, with females tending to be heavier than males. Otherwise, there is little sexual dimorphism. Its skull is shorter and wider than other eastern sifakas'. It has small, brown, forward-facing eyes. The salivary glands are very large. Its deciduous dental formula is 2.1.22.1.2. The deciduous incisors erupt before birth. Adolf Remane interpreted the permanent dental formula as 2.1.2.32.0.2.3, wherein the lower deciduous canines are not replaced. Other scholars, such as William Warwick James and Daris Swindler, have argued that the lower deciduous canines are instead replaced by an incisor-like tooth, and that it is two of the lower deciduous incisors that are not replaced, giving the appearance of 2.1.2.32.0.2.3 despite being 2.1.2.31.1.2.3. In either case, Perrier's sifaka differs from lemurs outside of the Indriidae and Daubentoniidae families in that its toothcomb consists of four, rather than six, incisor-shaped teeth, and it has two, rather than three, permanent premolars. Its pelage is almost entirely black, and the ventral coat has a brownish tint. All but the face is furred, though some individuals' ears are bald. The digestive tract of Perrier's sifaka includes a long cecum without an appendix or appendix-like structure. The cecum typically exceeds the body length of an adult, though it is relatively smaller in immature individuals. The cecum has three rows of sacculations, which do not develop until after birth. The first colon is arranged as a large, oval-shaped spiral called a tortillon, which may play a role in preventing blockages. This differs from the smaller, corkscrew-shaped spirals seen in the colons of strepsirrhines outside of the Propithecus and Indri genera. Beyond the tortillon is a dorsal second colon, which terminates into the rectum without structural demarcation. Overall, the lower gastrointestinal tract of Perrier's sifaka is about nine times an individual's body length.

Behavior Perrier's sifakas use vocalizations to communicate including warning calls and have even been observed to make a sound described as sneezing.

Social Structure Sifakas have groups of two to six individuals. Dispersal of sex is unbiased, which is uncommon among most species. Aggression between groups is extremely low, as is the overall encounter rates between groups. Society is largely matriarchal and females have feeding priority. Mating habits have not been thoroughly studied yet.

… excerpt ends here. Continue reading the full article.