Onitis vanderkelleni

Beneficial

Common name(s)

none known

Taxonomy

Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Onitis Species: Onitis vanderkelleni Lansberge, 1886

Adult diagnosis

Total body length 18.0–26.0 cm (0.71–1.02 in). Body shape subquadrate posteriorly; may be caked in dried dung. Color dull black. Clypeal apex rounded to weakly sinuate. Frons with weak, central tubercle. Front tibia of male elongate, curving ventrally and inward at apex; female tibia somewhat shorter; tarsi lacking in both sexes. Tibia of middle leg gradually expanded to a triangulate apex. Hind trochanter lacking spine on posterior margin in both sexes. Hind femur of male with well-developed, posteriorly produced, straight spine; female lacking spine.

Larval diagnosis

Undescribed. For Scarabaeinae (Ritcher, 1966): Grub C-shaped, hump-backed, cylindrical, cream-colored. Maxilla with galea and lacinia distinctly separate. Antennae with 4 or 5 apparent segments. Distal segment of antenna much reduced in size. Epipharnyx with tormae united mesally, anterior phoba present. Anal opening surrounded by fleshy lobes. Legs 2-segmented.

Native range

Africa. This species occurs in the tropical highlands of sub-Saharan Africa, with records from Angola, Burundi, Cameroon, Kenya, Rwanda, Tanzania, Uganda, and the Democratic Republic of the Congo (formerly Zaire) (Krikken, 1977). It usually occurs at elevations over 1,800 meters (5,900 ft) where rainfall ranges from 800–2,000 mm (31–79 in) per year (Edwards, 2007).

Plant host(s)

None. Onitis spp. feed on dung as both adults and larvae (Edwards and Aschenborn, 1987).

Life history

Poorly known. Related species of Onitis are dung burrowers. A vertical tunnel lined with dung is created under the initial dung source. Adult male and female beetles cooperate to transport dung pieces down the burrow where the dung is shaped into sausage-like masses. An egg (or eggs) is deposited into each of the dung sausages, and larval development occurs within the dung mass.

Pest potential

None. This species recycles dung and is beneficial for ranching and farming in Hawaii. Being a dung feeder, this species poses no threat to crop or ornamental plants. Additionally, this species is not a threat to native dung beetles because none are known from Hawaii or Guam.

Status in Hawaii

Established. Onitis vanderkelleni was released in 1976 at Parker Ranch on Big Island (Nakao and Funasaki, 1979) where it is now established (Nishida, 2002). Like most of Hawaii's dung beetles, this species was introduced to help control populations of the horn fly (Haematobia irritans), a biting pest of livestock.

Status in Guam

Not established or recorded. There are no records of this species from Guam.

Potential distribution and dispersal pathway

In Hawaii, this species was intentionally introduced.

Similar species

Three species of Onitis are recorded from Hawaii (none are known from Guam). Onitis vanderkelleni can be separated from the other Onitis species by examination of the middle tibia (O. vanderkelleni with gradually expanded middle tibia with a triangulate apex versus O. phartopus with an abruptly expanded tibia with trapezoidal apex), the hind trochanter (O. vanderkelleni hind trochanter lacking spine-like process versus trochanter with a well-developed spine in male O. phartopus), hind femur of male (O. vanderkelleni with a posteriorly produced, straight spine versus O. alexis with a curved spine and O. phartopus that lacks a spine), and color (O. vanderkelleni dull black versus greenish-black with brown elytra in O. alexis).

Other names (synonyms)

none known

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Onitis vanderkelleni male; photo by E.L. Engasser

Onitis vanderkelleni male; photo by E.L. Engasser

Onitis vanderkelleni male; photo by E.L. Engasser

Onitis vanderkelleni male; photo by E.L. Engasser

Onitis vanderkelleni male hind legs, ventral view; photo by E.L. Engasser

Onitis vanderkelleni male hind legs, ventral view; photo by E.L. Engasser

Onitis vanderkelleni female hind legs, ventral view; photo by E.L. Engasser

Onitis vanderkelleni female hind legs, ventral view; photo by E.L. Engasser

Onitis vanderkelleni male genitalia, dorsal view; photo by E.L. Engasser

Onitis vanderkelleni male genitalia, dorsal view; photo by E.L. Engasser

Onitis vanderkelleni male genitalia, lateral view; photo by E.L. Engasser

Onitis vanderkelleni male genitalia, lateral view; photo by E.L. Engasser

distribution map for Onitis vanderkelleni

distribution map for Onitis vanderkelleni