Key to adults of Nitidulidae

species commonly associated with nut orchards in south eastern Australia and some closely related species* (adapted, in part, from Leschen & Marris 2005 and Connell 1991)

1 Abdomen usually with at least three exposed tergites (Fig. 8C,I)................................................ 2

- Abdomen with two exposed tergites (Fig. 8D–H)............................................................ 3

2 Body with lateral margins slightly curved (Fig. 8I), dorso-ventrally convex; pronotal margin (in lateral view) with bead twice as thick along anterior half as along posterior half (Fig. 8B); elytra with punctures scattered randomly............................................................................................. Urophorus humeralis (Fabricius)

- Body with lateral margins more or less parallel-sided (Fig. 8C), strongly flattened dorso-ventrally; pronotal margin with thickness of bead even throughout (Fig. 8A); elytra with punctures in distinct rows, parallel along elytra length................................................................................................. Brachypeplus spp.

3 Mesosternal disc with raised carinae bearing oblique lateral arms (Fig. 9A)........................................4

- Mesosternal disc without carinae (Fig. 9B)................................................................. 5

4 Elytra with posterior half bearing distinct pale orange markings (M-shaped) and orange patches on anterior lateral humeral angles (Fig. 8F).................................................................... C. hemipterus (Linnaeus)

- Elytra dark brown, black without any distinctive orange colour patterns although sometimes with faint humeral angles (Fig. 8J)................................................................................ C. obsoletus (Erichson)

5 Metaventrite with large axillary space, axillary line almost straight and extending to at least half way to 2/3 length along metepisternum (Fig. 9C)......................................................... C. marginellus Motschulsky

- Metaventrite with small axillary space, line curved reaching ¼ length along metepisternum or axillary space not clearly present (Fig. 9D).............................................................................................6

6 Prosternum weakly punctate or granulate (Fig. 9H), often convex and shiny in appearance; body often ventrally bicoloured, metaventrite usually darker than prosternum and abdomen but may be unicoloured; female 9th tergite truncate with median apical tubercle (Fig. 9E)................................................................ C. davidsoni Dobson

- Prosternum moderately to distinctly punctate (Figs 1D,I, 9G); body unicoloured ventrally; female 9 th tergite without distinct median tubercle...................................................................................... 7

7 Male metatibia, not constricted at base, gradually widened towards apex (Fig. 9I).................................. 8

- Male metatibia distinctly and abruptly constricted along basal 1/3 to ¼, widened towards apex (Figs 1E,J, 7E).......... 10

8 Prosternum and hypomeron distinctly punctate (Fig. 9G); 3 rd antennomere about 1.3x length of 2 nd antennomere........................................................................................... C. dimidiatus* (Fabricius)

- Prosternum distinctly to moderately punctate or granulate, hypomeron weakly punctate (Figs 1D,I, 3C,G, 4C); 3 rd antennomere less than 1.3x length of 2 nd antennomere (Fig. 1C,H)......................................................... 9

9 Body chestnut brown with no distinctive pattern (Fig. 8G); male mandibles asymmetrical, right mandible distinctly elbowed (right angled) (Fig. 9F); prosternum entirely punctate........................................ C. mutilatus Erichson

- Body generally reddish brown, elytra golden brown but usually with a distinctive dark brown band across posterior margin (Fig. 8H); male mandibles are symmetrical; prosternum punctate medially but laterally only weakly punctate or granulate............................................................................................. C. nepos* Murray

10 Body length 2.8 to 3.4 mm (> 2.5 mm); body dark brown/ black, anterior lateral margin of elytra with a pale brown/ orange patch (Figs 1A,F, 3A,E); male paramere, is distinctly truncate apically, outer apical angle with slight tooth, mesal margin distinctly angled around mid-length (Fig. 2B,E)...................................................... C. truncatus Murray

- Body length small, around 2.0 to 2.4 mm; body uniformly brown (not usually black and no paler patches on elytra) (Fig. 7A,H); male paramere roundly truncate, (not distinctly truncate) outer apical margin somewhat rounded, mesal margin slightly concave around mid-length but not distinctly angled (Fig. 7F)........................................... C. imitatus sp. nov.

Note: Only Carpophilus truncatus was found damaging nuts in the current study. All other species in this key were collected in pheromone lures within almond and pistachio orchards, or are closely related species (as marked with an asterisk), which could be confused with C. truncatus.