Tridemula metabates Wygodzinsky 1956

Tridemula metabates Wygodzinsky 1956: 211 (new species); Wygodzinsky 1966: 417 (description); Cassis & Gross 1995: 303 (catalogue); Tatarnic et al., 2011 (tribal revision).

Diagnosis. This species can be recognised in Australia (including Lord Howe Island) by the following combination of characters: posterior lobe of pronotum lacking a medial tubercle, lateral margins predominantly stramineous below lateral carina, first labial segment stramineous to cream coloured, and dorsal surface of forefemora without tufts of hair.

Distribution. Eastern Australia and Lord Howe Island.

Specimens examined. AUSTRALIA: New South Wales: Lord Howe Island: SE aspect of Transit Hill, near summit, 31.357o S 159.078o E, 24 November 2000, M. Elliot & N. Plunkett-Cole, site LHIS019/02B, ex Pouteria myrsinoides, beating, 1Ƥ (AM).

Remarks. A recent revision of the Australian Ploiariolini (Tatarnic et al. 2011) keys out all three Australian species of Tridemula (T, metabates, T. contumax and T. pilosa Horváth), based on the following: presence or absence of a tubercle on the hind lobe of the pronotum (absent only in T. metabates); the relative size of the eye (1/ 2 length of head in T. pilosa, 1/3 length of head in T. contumax); and primarily chestnut colouration below the lateral pronotal carina plus absence of annulations on metafemur (T. pilosa) versus stramineous lateral pronotal colouration plus apical annulations on metafemur (T. contumax).

Due to a paucity of specimens, there are questions concerning the identity of T. metabates. Wygodzinsky (1956) originally described this species from two specimens, a male from Queensland (Brisbane) and a female from Lord Howe Island. He considered the two conspecific because of their agreement “of all general characters”. The female specimen that has been collected in our recent survey complies very closely with the original description, including colour characters of the head, pronotum, thoracic pleura and the forewing. As males of this species have yet to be collected from Lord Howe Island, the corroboration of conspecificity of the two populations cannot be made. Since this species is fully winged (in contrast with the aptery or submacroptery of other Lord Howe emesines), such a disjunct distribution remains plausible, and we therefore retain Wygodzinsky’s (1956) original conception of the species.