Sharp-Grooved Diving Beetle vs Formosa Long-armed Scarab

Side-by-side species comparison

Attribute Sharp-Grooved Diving Beetle Formosa Long-armed Scarab
Scientific Name Acilius sulcatus Cheirotonus formosanus
Order Coleoptera Coleoptera
Family Dytiscidae Euchirinae
Size 15-18 mm 40-60 mm
Habitat Ponds & Lakes Forests
Diet Predators Sap Feeders
Regions Europe, Western Asia Taiwan
Conservation Least Concern Endangered

Sharp-Grooved Diving Beetle

A medium-sized diving beetle widespread across Europe, recognized by the deeply grooved elytra of females. It is a fast and agile predator in ponds.

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Did You Know?

Females have deeply furrowed elytra that prevent males from gripping them, giving them control over mating.

Formosa Long-armed Scarab

A rare Taiwanese scarab with elongated forelimbs and a dark chestnut-brown body. It is found only in old-growth mountain forests on the island.

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Did You Know?

Illegal collecting for the pet trade has made this one of the most threatened beetles in East Asia.