Melanterius castaneus Lea, 1899

(Figs. 3–4, 11, 20–21)

Melanterius castaneus Lea, 1899: 229

Melanterius compactus Lea, 1899: 241; Pullen et al., 2014: 226 (syn.)

This is largely a West-Australian species, described from Pinjarra and Donnybrook and (the synonym compactus) from Perth ( Swan River). It occurs throughout south-western Western Australia but has also been recorded from Callington and Murray Bridge in South Australia (Lea, 1913). It is recognisable by its short, stocky body shape, compact antenna, flat (acostate) elytral interstriae (Fig. 11) and coloration (dark pronotum, reddish elytra). Its male genitalia (Fig. 21) are also distinctive, the penis broadly rounded at the apex and carrying pairs of long endophallic sclerites near the apex and at the base of the body.

The species was first reared from seeds of Acacia saligna in 1975 (van den Berg, 1980) and appears restricted to this host, against which it was released in South Africa in 2001, under the name M. compactus (Impson & Moran, 2004) . It causes extensive damage to its host and is regarded as the most successful of all the Melanterius species imported into South Africa to combat the invasive acacias (Impson et al., 2011). We collected 18 specimens in the Esperance area of Western Australia on A. nigricans (Table 1), which appears to be another host for the species (Table 2).