Revised diagnoses for the pseudoscorpion genera Metawithius and Microwithius, with the description of a new Australian genus, and notes on Withius (Pseudoscorpiones, Withiidae)

© The American Arachnological Society. Pseudoscorpions of the family Withiidae are distributed in most regions of the world, but are less common in the Australian region. Apart from the cosmopolitan genus Withius Kew, 1911, the fauna is dominated by the endemic genera Metawithius Chamberlin, 1931 and Hyperwithius Beier, 1951. A review of material of both genera reveals that Metawithius is a senior synonym of Hyperwithius, and is defined by the presence of a patch of rugose cuticle on the internal surface of the male maxilla. The genus contains the following taxa: M. Murrayi (Pocock, 1900), M. philippinus Beier, 1937, M. Spiniventer Redikorzev, 1938, M. Spiniventer pauper Beier, 1953, three species newly transferred from Hyperwithius to Metawithius, M. annamensis (Redikorzev, 1938), comb. Nov., M. tonkinensis (Beier, 1951), comb. Nov. and M. dawydoffi (Beier, 1951), comb. Nov., and M. Nepalensis (Beier, 1974) which is newly transferred from Withius. The remaining species previously attributed to Metawithius are transferred to other genera, primarily because they lack the patch of rugose cuticle. The subgenus Metawithius (Microwithius) Redikorzev, 1938 is once again raised to generic level, and provisionally contains four species, M. yurii Redikorzev, 1938 from southeast Asia, and M. indicus (Murthy and Ananthakrishnan, 1977), comb. Nov., M. Chamundiensis (Sivaraman, 1980), comb. Nov. and M. bulli (Sivaraman, 1980), comb. Nov. from India. Metawithius (Microwithius) tweediei Beier, 1955 also lacks the rugose patch of cuticle and is provisionally transferred to Withius, forming the new combination W. tweediei (Beier, 1955). Two new species from northern Australian rainforests are found to be most similar to Metawithius but instead of an internal patch of rugose cuticle, they have an external patch. These new species, R. bulbosus sp. Nov. (type species) and R. longissimus sp. Nov., are placed in a new genus, Rugowithius. Afrowithius Chamberlin, 1931 is regarded as a new synonym of Withius, and the type species Chelifer paradoxus Ellingsen, 1912 from South Africa is treated as a senior synonym of Withius crassipes (Lawrence, 1937).