Onthophagus laminatus

Beneficial

Common name(s)

none known

Taxonomy

Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Onthophagus Species: Onthophagus laminatus MacLeay, 1864

Adult diagnosis

Total body length 11.0–22.0 mm (0.43–0.86 in). Body shape oval; may be caked in dung. Color shiny black. Small to medium-sized Onthophagus, over 6 mm. Clypeal apex weakly produced in major male; apex not produced in minor male or female. Head of major male with two upward curving horns, apex of horns not bifurcate, distinct transverse ridge between horns; horns lacking in minor male and female; female and minor male with transverse (straight) ridge at base of head. Ocular canthus completely dividing eye. Pronotum with lobe-like process in major male, process reduced in minor male and female. Anterior angles of pronotum curved outward in both sexes. Front tibia of male slightly slender and elongate; female tibia somewhat more robust. Scutellum absent.

Larval diagnosis

Undescribed. For Onthophagus spp. (Ritcher, 1966): Grub C-shaped, hump-backed, cylindrical, and cream-colored. Maxilla with galea and lacinia distinctly separate. Epipharynx with tormae united mesally, anterior phoba present. Antennae 4-segmented, distal segment much reduced. Legs 2-segmented. Prothoracic shield without anteriorly projecting processes. Third abdominal segment bearing a prominent conical, dorsal gibbosity covered with numerous short, stout setae.

Native range

Australia and New Guinea. This species is native to New Guinea and tropical northern Australia. In Australia, it is found from Derby in Western Australia eastward to Gladstone in Queensland (Matthews, 1972).

Plant host(s)

None. This species feeds on dung as both an adult and larva. There are no records of this scarab feeding on live plant tissues.

Life history

This nocturnal species is associated with pastures and open woodland in areas with annual rainfall that exceeds 76 cm (30 in) (Matthews, 1972). Adults are recorded from cattle and horse dung. Life history of the species is poorly known, but related Onthophagus species are dung tunnelers, with females creating a burrow under or near dung (Woodruff, 1973). The burrow is then provisioned with dung in the form of brood balls. Each ball is impregnated with an egg; larval development occurs within the brood ball.

Pest potential

None. This species recycles dung and is beneficial for ranching and farming in Hawaii. Primarily being a dung feeder, this species has never been recorded damaging crop or ornamental plants. Additionally, this species is not a threat to native dung beetles because none occur in Hawaii or Guam.

Status in Hawaii

Recorded, not established. This species was intentionally brought to Hawaii in 1921, though it is appears no specimens were released (Hawaii Division of Forestry, 1923).

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 imported.

Similar species

This dung beetle could easily be confused with similarly colored and small to medium-sized (more than 6 mm) Onthophagus species such as Onthophagus binodis, Onthophagus cuniculus, Onthophagus incensus, Onthophagus armatus, and Onthophagus comperei.

Size can be used to distinguish both sexes of Onthophagus laminatus from O. armatus and O. comperei (O. laminatus is 11.0–22.0 mm [0.43–0.86 in] versus O. armatus and O. comperei that are both under 11.0 mm [0.43 in]).

Major males of these species can be separated by examining the head armature (O. laminatus has two upward curving, non-bifurcate horns connected by a distinct ridge versus O. binodis and O. cuniculus that lack horns or tubercles, O. incensus and O. comperei that lack a ridge between the horns, O. armatus that has a distinctly bisinuate ridge connecting the horns).

Minor males and females can be differentiated by examining the rear of the head (O. laminatus with transverse (straight) ridge versus O. binodis with slightly curved ridge, O. armatus with feebly bisinuate ridge, O. comperei with two tubercles), pronotum (O. laminatus with lobe-like process versus O. cuniculus with bi-lobed process, and O. incensus, O. armatus and O. comperei all lacking a distinct process), and the anterior angles of the pronotum (O. laminatus with anterior angles curved outward versus O. binodis, O. armatus, O. comperei and O. incensus all with the anterior angles rounded or quadrate).

Other names (synonyms)

Onthophagus cowleyi Blackburn, Onthophagus palmerstoni Blackburn

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Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus major male; photo by E.L. Engasser

Onthophagus laminatus minor male; photo by E.L. Engasser

Onthophagus laminatus minor male; photo by E.L. Engasser

Onthophagus laminatus minor male; photo by E.L. Engasser

Onthophagus laminatus minor male; photo by E.L. Engasser

Onthophagus laminatus male genitalia, caudal view; photo by E.L. Engasser

Onthophagus laminatus male genitalia, caudal view; photo by E.L. Engasser

Onthophagus laminatus male genitalia, lateral view; photo by E.L. Engasser

Onthophagus laminatus male genitalia, lateral view; photo by E.L. Engasser