Eucalyptus costuligera

Eucalyptus costuligera is a species of small tree that is endemic to the Kimberley region of Western Australia. It has short-fibrous or flaky bark on the trunk and branches, bluish, lance-shaped adult leaves, club-shaped flower buds in branched or unbranched inflorescences with the buds in groups of up to seven, creamy-white flowers and conical, cup-shaped or pear-shaped fruit.

Description
Eucalyptus costuligera is a tree that typically grows to a height of 5-10 m and has persistent pale grey, fibrous or flaky "box"-type bark on the trunk and branches. The adult leaves are arranged alternately, the same grey-green or bluish colour on both sides, lance-shaped, 70-150 mm long and 17-30 mm wide on a channelled or flattened petiole up to 22 mm long. The flower buds are arranged in groups of up to seven on a branched or unbranched peduncle 1-15 mm long, the individual buds on a pedicel 2-6 mm long. Mature flower buds are club-shaped, about 7 mm long and 4 mm wide with faint ribs along the sides. The operculum is hemispherical, about half as long as the floral cup. The flowers are a white-cream colour and the fruit is a woody cylindrical, cup-shaped or pear-shaped capsule 6-8 mm long and 5-7 mm wide with fine ribs along the sides and the valves enclosed below the rim.

Taxonomy and naming
Eucalyptus costuligera was first formally described in 2000 by Lawrie Johnson and Ken Hill from a specimen collected 60 km from the Derby-Gibb River Road, on the road to Wyndham. The specific epithet (costuligera) is derived from the Latin costula, meaning "a costule or rib" (strictly the midrib of a fern frond) and -ger meaning "-bearing", referring to the finely ribbed fruit.

Distribution and habitat
This eucalypt has a limited range but is abundant in a small area in the central Kimberley region of Western Australia, growing in savannah woodland in sandy to loamy soils over laterite.

Conservation status
This species is classified as is classified as "Priority One" by the Government of Western Australia Department of Parks and Wildlife meaning that it is known from only one or a few locations which are potentially at risk.