Temporal Pouch in Chameleons of the genus Furcifer

Among these remarkable features, the temporal gland stands out due to its mysterious nature. This gland, also referred to as the temporal pouch, is a holocrine type of exocrine gland found in several chameleon genera (including Bradypodion, Chamaeleo, Kinyongia, Rieppeleon, Furcifer, and Trioceros). It is a flat pocket located above the angle of the mouth and secretes its products through ducts into the outer cells, rather than into the bloodstream. (Nečas 1995)

In the 1960s, Ogilvie (1966) observed chameleons wiping their jaws against tree branches, smearing a foul-smelling, waxy material on the bark. He suggested that the pouch contained the remains of sloughed-off skin cells and rotting bits of food, which might be used to lure prey closer. He based his Doctoral Dissertaion on these findings. 

Preest & al. (2016) confirmed that Chamaeleons use a viscous substance from a temporal pouch at the jaw angle to attract flies. This pouch, confirmed in Jackson's chameleons, contains decomposed food and sloughed skin, not glandular secretions. Gas chromatography–mass spectrometry revealed volatile compounds similar to insect pheromones. Tests showed houseflies are attracted to the pouch material, suggesting its role in prey luring, in addition to territory marking and predator deterrence. (DeMarco 2016, Stein 2023)

The representatives of the genus Furcifer possess the  Temporal Pouch, however, it seems vestigial and un-functional. No smell is sensed and no rubbing of its content on branches observed. Also, it is vividly pigmented same as surrounding mucous tissue of the mouth cavity, not with melanin protection like eg the representatives of the genus Trioceros.

DeMarco, E. (2016). Why Chameleons Sometimes Smell Like Rotting Meat. Inside Science. Retrieved from Inside Science.

Böhme, W. (1994). Chamäleons: Farben, Formen, Fortpflanzung. Datz, 4, 241-244.

Nečas, P. (1995): Chamäleons-Bunte Juwelen der Natur. - Edition Chimaira, Frankfurt, 1. Aufl.: 249 S.

Ogilvie, P. W. (1966). An Anatomical and Behavioral Investigation of a Previously Undescribed Pouch Found in Certain Species of the Genus Chamaeleo. Ph.D. Dissertation, University of Oklahoma.

Preest, M. R., Ward, M. J., Poon, T., & Hermanson, J. W. (2016). Chemical Prey Luring in Jackson's Chameleons. Physiological and Biochemical Zoology, 89(2), 136-145. DOI: 10.1086/686090.

Stein, E. (2023). The Temporal Gland & Its Function | An interview with Petr Necas. Reptile Apartment. Retrieved from Reptile Apartment.