The red slender loris (Loris tardigradus) is a small, nocturnal strepsirrhine primate native to the rainforests of Sri Lanka. This is No. 6 of the 10 focal species and No. 22 of the 100 EDGE mammal species worldwide considered the most evolutionarily distinct and globally endangered. Two subspecies have been identified, L. t. tardigradus and L. t. nycticeboides. Taxonomy Genus Loris Red slender loris, Loris tardigradus Horton Plains slender loris or mountain loris, Loris tardigradus nycticeboides Dry zone slender loris or lowland loris, Loris tardigradus tardigradus Gray slender loris, Loris lydekkerianus The ears are less prominent in Loris tardigradus tardigradus compared to Loris lydekkerianus. The ears of Loris tardigradus nycticeboides are almost invisible. Description This small, slender primate is distinguished by large forward-facing eyes used for precise depth perception, long slender limbs, a well-developed index finger, the absence of tail, and large prominent ears, which are thin, rounded and hairless at the edges. The soft dense fur is reddish-brown color on the back, and the underside is whitish-grey with a sprinkling of silver hair. Its body length on average is , with an average weight of a mere . This loris has a four-way grip on each foot. The big toe opposes the other 4 toes for a pincer-like grip on branches and food. It has a dark face mask with central pale stripe, much like the slow lorises. L. tardigradus tardigradus is reddish brown in the back and creamy yellow below, while L. tardigradus nycticeboides is dark brown dorsally and very light brown in upperparts. Behavior The red slender loris favors lowland rainforests (up to 700 m in altitude), tropical rainforests and inter-monsoon forests of the south western wet-zone of Sri Lanka. Masmullah Proposed Forest Reserve harbors one of few remaining red slender loris populations, and is considered a biodiversity hotspot. The most common plant species eaten was Humboldtia laurifolia, occurring at 676 trees/ha, with overall density at 1077 trees/ha. Humboldtia laurifolia is vulnerable and has a mutualistic relationship with ants, providing abundant food for lorises. Reports from the 1960s suggest that it once also occurred in the coastal zone, however it is now thought to be extinct there. The red slender loris differs from its close relative the gray slender loris in its frequent use of rapid arboreal locomotion. It forms small social groups, containing adults of both sexes as well as young animals. This species is among