MACROGYRUS SENSU

SUBGENUS MACROGYRUS SENSU NOV.

( FIGS 2 View Figure 2 , 4B View Figure 4 , 5A View Figure 5 , 7F View Figure 7 , 9B–C View Figure 9 , 10 View Figure 10 , 12D–E View Figure 12 , 13F View Figure 13 )

Type species: Macrogyrus howittii ( Clark, 1866) .

Synonyms: Australogyrus Ochs, 1949 syn. nov., Ballogyrus Ochs, 1949 syn. nov., Clarkogyrus Ochs, 1949 syn. nov., Megalogyrus Ochs, 1949 syn. nov., Orectomimus Ochs, 1930 syn. nov., Tribologyrus Ochs, 1949 syn. nov., Tribolomimus Ochs, 1949 .

Diagnosis: Within the genus Macrogyrus , the sensu stricto subgenus can be diagnosed by the following combination of character: (1) clypeus neither narrow nor considerably enlarged ( Fig. 4B View Figure 4 ), (2) elytra with unique canaliculate microsculpture ( Fig. 10B–C View Figure 10 ) and (3) metaventral discrimen of most species with well developed transverse sulcus ( Fig. 10A View Figure 10 ). The unique canaliculate microsculpture ( Fig. 10B–C View Figure 10 ) is an excellent autapomorphy for the sensu stricto subgenus. This character is strongly reduced in one species M. sumbawae ( Fig. 2 View Figure 2 ), but is still faintly evident apically on the elytra.

Taxonomy: There are now 29 species within this subgenus, a massive increase from the former classification, in which the subgenus only contained the type species, M. howittii ( Ochs, 1949) . The Australian species are the most well known ( Ochs, 1949, 1956) and were recently treated by Watts & Hamon (2010), making their identification possible. The New Guinean fauna and those of the surrounding islands are in desperate need of revision following the work of Ochs (1955), in which the few known species were divided into numerous subspecies, from disparate locations in New Guinea, based on few specimens. The work of Ochs (1955), including no illustrations, nondiscrete morphological characters and excessive splitting of species, has made the identification of New Guinean specimens exceptionally difficult. For this reason, most species in the analysis were unable to be identified reliably.

Distribution: Primarily known from Australia and New Guinea, also found in the islands surrounding New Guinea and the Lesser Sunda Islands ( Ochs, 1949, 1955).

Discussion: The new definition of the sensu stricto subgenus is based on the earliest diverging taxon, suggesting a common ancestor, with canaliculate microsculpture ( Figs 10B–C; S View Figure 10 9 View Figure 9 , character 41), which in this analysis is M. striolatus . However, the placement of M. striolatus is weakly supported ( Figs 2 View Figure 2 , S 4 View Figure 4 ). It is possible that the subgenus Cyclomimus is nested within the sensu stricto subgenus, as examination of the.t tree files from the Bayesian analysis show the placement of M. striolatus fluctuating between a position above or below the Cyclomimus clade. In the case M. striolatus is truly earlier diverging than the Cyclomimus clade, the putative synapomorphic character of the sensu stricto subgenus still stands, with an inferred subsequent loss of the canaliculate microsculpture in Cyclomimus . Reduction of the canaliculate microsculpture is seen in the more derived members of the sensu stricto subgenus, e.g. M. sumbawae ( Fig. 2 View Figure 2 ) and other species found in Wallacea. The species of Cyclomimus show other highly derived characters (e.g. the reduction in number and expansion in size of adhesive setae of the male protarsus; a largely expanded clypeus, reduction of the transverse sulcus of the metaventral discrimen). Therefore, a convergent derived loss of the canaliculate microsculpture is certainly plausible. Because of the strong support for the monophyly of the Cyclomimus subgenus in the analysis it is currently retained as a valid subgenus separate from the sensu stricto, but the composition of Macrogyrus s.s. may be subjected to change in future phylogenetic analyses depending upon the placement of M. striolatus .