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Home » Guide » Arthropods (Arthropoda) » Hexapods (Hexapoda) » Insects (Insecta) » Beetles (Coleoptera) » Adephaga » Predaceous Diving Beetles (Dytiscidae) » Dytiscinae » Aciliini » Acilius

Genus Acilius

Classification · Synonyms and other taxonomic changes · Explanation of Names · Numbers · Size · Identification · Range · Habitat · Season · Life Cycle · Works Cited

gray-brown diving beetle - Acilius sylvanus - female

Acilius sp. - Acilius semisulcatus - female

Acilius athabascae (Larson) - Acilius athabascae

female diving beetle - Acilius confusus - female

Acilius (mediatus?) Diving Beetle - Acilius mediatus

Classification

Kingdom Animalia (Animals)

Phylum Arthropoda (Arthropods)

Subphylum Hexapoda (Hexapods)

Class Insecta (Insects)

Order Coleoptera (Beetles)

Suborder Adephaga

Family Dytiscidae (Predaceous Diving Beetles)

Subfamily Dytiscinae

Tribe Aciliini

Genus Acilius

Synonyms and other taxonomic changes

revised in (1)

Explanation of Names

Acilius Leach 1817

Numbers

7 spp. in our area, 13 total(2)(1)

Size

adult 10‒16 mm, larva 15‒30 mm

Identification

Adult: top of head yellowish with two dark transverse bands, the anterior band undulate or M-shaped; pronotum yellowish with two dark transverse bands on disc, not terminally, as in Graphoderus; notched spur on hind tibia; elytral mottling or speckling less pronounced than in Graphoderus; elytra punctate (and longitudinally sulcate in female)

Larva: swimming hairs present on last two abdominal segments; ligula deeply bifid

in Graphoderus elytra more heavily mottled/speckled, and dark transverse pronotal bands located apically

key to spp. in (1)

Range

Holarctic, widespread (including the arctic)(1)

Habitat

submergent vegetation

Season

Year-round with adults most frequently encountered in spring during mating season and late summer when they disperse

Life Cycle

Adults overwinter in permanent water bodies and disperse to breeding sites during spring; larvae complete development later in the spring and into the early summer; newly emerged adults disperse to overwintering sites later in summer/fall(3)

Works Cited

1.	Taxonomic revision of the Holarctic diving beetle genus Acilius Leach (Coleoptera: Dytiscidae) Bergsten, Johannes & Miller, Kelly B. 2006. Systematic Entomology, 31: 145-197.

2.	A World Catalogue of the Family Dytiscidae, or the Diving Beetles (Coleoptera, Adephaga) Nilsson and Hajek. 2019. Distributed by authors.

3.	Predaceous Diving Beetles (Coleoptera: Dytiscidae) of the Nearctic Region, with emphasis on the fauna of Canada and Alaska D.J. Larson, Y. Alarie, and R.E. Roughley. 2001. NRC 43253.

Contributed by Eric R. Eaton on 21 November, 2005 - 1:21pm
Additional contributions by Robin McLeod, t.loh, v belov, Claude Tessier
Last updated 3 July, 2024 - 3:05pm

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