Family Corixidae - Water Boatmen

the largest water bug family, with ~125 spp. in 16 genera in North America north of Mexico(1) and >600 spp. in 35 genera worldwide(2) arranged in 6 subfamilies(3)

Overview of our fauna (* –taxa not yet in the guide):

Family Corixidae

Subfamily Cymatiainae Cymatia

Subfamily Corixinae

3-11 mm(1) (1.5-16 mm worldwide(3))

Dorsum flattened, with narrow dark crosslines. Front legs short, tarsi 1-segmented and scoop-shaped. Hind legs oar-like, with fine hairs(11)

Critical сharacters for genus identification: Members of different genera can be superficially similar. For image-based genus-level identification please provide:

1) Both dorsal and ventral habitus shots of preferably dry specimen (water can obscure colour pattern, texture of hemielytra, etc. key feature)

2) Lateral view. The key diagnostic traits here are the nodal furrow and translucent (pruinose) areas on the claval suture and the area immediately posterior to the nodal furrow.

3) Facial shot showing rostrum details.

4) Shot of the upper ventral half of the body showing prothoracic lobes, mesepimeron, and scent glands.

5) Shot of the dorsal abdominal segments (tergites)- sex determination often relies on examination of the dorsal terminal segments; males generally have asymmetrical dorsal terminalia and may or may not have a black spot-like structure called a "strigil" depending on genus; females have symmetrical terminalia.

6) Palae, especially of the male- of some importance in genus identification but generally more critical in species ID.

Size may also be important, as some genera have a specific size range.

Keys to genera in(12)(5)(13); keys to spp. in (14). Species identification requires examination of specific features, e.g. genitalia, male palae (front tarsi), ventral structures, etc. Species of some genera may be identifiable from photos, but spp. of Sigara, Hesperocorixa, etc. large genera are unlikely to be identifiable.

Keys to spp. MI(5), FL(6), CA(15); key to AB genera in(13)

Worldwide and throughout NA

Common in ponds. Also found in birdbaths. A few species live in streams, and others are found in brackish pools along the seashore above the high tidemark.

Algae, detritus, other aquatic organisms (mosquito larvae, brine shrimp)(2); a few (uniquely among Hemiptera) consume small particles of solid food(1)

eggs are cemented to underwater objects, sometimes forming a dense mat(1)

Notonectidae (Corixidae swim dorsal side up, Notonectidae swim upside down)