The Catalogue of Aru by Bigger & Schoefield (1983) did not provide a species like that. However, there are no many possibilities: it might belong to Stenhomalus. Have you checked the abdomen?
mmhm... not easy now. There is a recent paper that might be interesting for you: NIISATO T. & WEIGEL A., 2005 - Additional notes on the Genus Stenhomalus White, 1855, from New Guinea (Coleoptera: Cerambycidae) - Veröffentlichung des Naturkundemuseums Erfurt 24: 101-107.