[9][10] The genus can be diagnosed among wingless cryptorhynchine weevils by the absence of a metanepisternum and by a synapomorphic structure of the tarsus with minute claws and a deeply incavated articulation of tarsomere 4.

The metathoracic spiracle located externally at the side of the metaventrite is a unique feature and may ensure sufficient respiration during thanatosis.

An animated 3D model of a Trigonopterus weevil reveals a number of mechanisms to maintain a stable defensive position.

[13] It is rod-shaped with a large external spiral flange, having an angular span of 410°, in excess of a full circle, which functions as a thread.

It is surmised that the development of this feature provided additional flexibility which permitted weevils to improve their climbing abilities, helped them keep steady when at rest, and to give a stronger leverage for piercing by the snout.