Family Scarabaeidae - Cheirotonus macleayi formosanus

Cheirotonus macleayi formosanus
Range: Taiwan
Size: 50 - 60 mm

Cheirotonus maclayi formosanus is a member of the very small scarab subfamily euchirinae. This group is known for the immensely long first pair of legs possessed by the males of the various species. C. maclayi formosanus is found only in Taiwan and is the largest beetle native to the island. It is now a protected species due to threats from habitat loss and over collecting.

Shown here is a pair of C. macleayi formosanus. Note the interestingly patterned elytra which bear many yellow-orange spots. Also, notice that the thorax, especially that of the male, is divided into two distinctive lobes with a prominent groove down the middle of the pronotal shield. Only the male has the enormously elongated first pair of legs, the function of which remains something of a mystery.

Photo courtesy of Roman Kocina.

Cheirotonus macleayi formosanus (pair) - Image © Roman Kocina

Cheirotonus macleayi formosanus (male) - Image © Roman Kocina

In this image of a male, you can easily see how very long the forelegs are. A long spine extends from where the upper portion of the leg meets the jointed, lower half. Males also possess a prominent frill of tiny hairs which project from underneath the sides of the pronotum. These hairs are much like those seen on the underside of the thoracic horn of the Dynastes species of the American tropics and subtropics. Euchirinines are unique scarabs, most of which are found only in the forested regions of southeast Asia. Little appears to be known of their biology in the wild, but the larval duration is said to be quite long, and captive breeding difficult . A species which is very similar in form, C. parryi, is widespread in Malaysia.

Photo courtesy of Roman Kocina.