Microcryptorhynchus, Lea, 1908

Zimmerman, Elwood C., 1942, Curculionidae of Guam, Insects of Guam I, Honolulu, Hawaii: Bernice P. Bishop Museum, pp. 73-146 : 114-115

Genus MICROCRYPTORHYNCHUS Lea

For a description of this genus, together with discussion and a chart of the distribution of the species, see my "Cryptorhynchinae of Rapa" (B. P. Bishop Mus., Bull. 151: 1938).

From a zoogeographical viewpoint, the discovery of four new species of Microcryptorhynchus on Guam is particularly significant. Heretofore, the most westerly known extension of the genus was along the east coast of Australia and King Island in Bass Straits off the south coast of Victoria and an isolated species collected by Lea on Mount Barker, north of Albany near the southwest tip of western Australia. It seems to me unusual that an isolated species should live in the Mount Barker vicinity, and I should like to have the locality data verified. Although Guam is not nearly so far west as the Mount Barker locality, it marks the most northwesterly extension of the genus thus far recorded. Only four species have been described from the vast area and numerous islands between New Caledonia and Guam, but many species will probably be found there. The description of the four Guam species brings the total number of species to 107 which show an almost continuous distribution from eastern Australia through New Caledonia, Fiji, Samoa and the Austral, Society, Marquesas and Mangareva Islands.

In my other studies of the genus I have called attention to the fact that each island or group of islands usually has its own complex or complexes of species displaying characters peculiar to that island or group. This phenomenon apparently holds true for the Guaman species, because, insofar as I now know, only in Guam are found species that have a sclerotized, conical, spinelike process at the base of the elytra on either side of the scutellum.

KEY To THE SPitcre:s oF MrcROCRYPTORHYNCHUS FouNn IN GUAM

1. All the elytral intervals distinctly setose; base of elytra without a sclerotized spine on either side of the scutellum......................................................................... 2

Only the alternate elytral intervals setose, base of elytra with a conical, sclerotized spine on either side of the scutellum (sometimes partially obscured by incrustation).............................................................................................. 3

2(1). Pronotum with no trace of a median carina; elytra conspicuously globose TODO TODO TODO TODO

Pronotum with a partial or almost complete, distinct median carina; elytra more ovate than globose................................................26. M.premnae Zimmerman.

3(1). Basal spine of elytra situated at the base of the setose third interval................ TODO TODO TODO TODO

Basal spine of the elytra situated at the base of the non setose second interval and so small as to be often almost concealed by the incrustation.................... TODO TODO TODO TODO