Rhysium separatum ( Martins and Galileo, 2007 ) Santos-Silva & Galileo & Wappes, 2017

Santos-Silva, Antonio, Galileo, Maria Helena M. & Wappes, James E., 2017, Descriptions, notes and reassignments in Neoibidionini (Coleoptera: Cerambycidae: Cerambycinae) with a new genus, three new species and keys to species of Brechmoidion Martins, 1969, Compsibidion Thomson, 1864 and Rhysium Pascoe, 1866, Insecta Mundi 2017 (560), pp. 1-21 : 15-16

Rhysium separatum ( Martins and Galileo, 2007) , comb. nov.

( Fig. 27–30 )

Brechmoidion separatum Martins and Galileo, 2007: 188 ; Monné 2016: 570 (cat.).

Discussion: Martins and Galileo (2007) described R. separatum as follows (translated): “Head, prothorax and ventral side of body reddish. Frons and vertex with yellowish, relatively long pubescence. Antennae orange-red; in male reaching elytral apex at apex of antennomere VII; in female as long as body. Scape cylindrical, with long pubescence primarily in basal half. Antennomere III carinate, slightly longer than IV (male) or longer than IV (female). Prothorax laterally slightly rounded at about midlength. Pronotum with slightly marked tubercles and yellowish setae except along center; in large males there is a small central, slightly rugose area. Elytra brownish, with sutural area reddish; each elytron with yellowish long band, starting on humerus and ending in distal quarter; this band is acuminate toward apex, involving small brownish spot behind midlength. Elytra with yellowish setae; with setiferous, asperous punctures on base; elytral apex unarmed. Femora orange-red, pubescent. Apices of metafemora not projected.”

Originally, Brechmoidion Martins, 1969 was separated from Rhysium in the alternative of couplet “12” from Martins (1969) (translated):

“12(11).Pronotum with five very evident tubercles, the central flattened on tip; apices of meso- and metafemora acute; apex of elytra acute at outer angle ....................................... Brechmoidion Tubercles of pronotum slightly marked, the central similar to the others; apices of meso- and metafemora rounded; elytral apex unarmed .............................................................. Rhysium ”

Later, Martins and Galileo (2007) modified the description of Brechmoidion to include their new species B. separatum . Brechmoidion and Rhysium were separated in the alternative of couplet “12” (translated):

“12(11).Pronotal tubercles well marked, the central elongated, when they are slightly marked the elytra are pubescent primarily in distal half; pronotum with abundant pubescence.......................... ....................................................................................................... Brechmoidion Martins 1969 Pronotal tubercles slightly marked; pronotum without pubescence in wide central area (except R. bivulneratum ).................................................................................... Rhysium Pascoe, 1866 ”

The second half of couplet 12 includes some problems: 1) The pronotal pubescence is not different between Rhysium and Brechmoidion , being moderately abundant except in a cross-shaped glabrous central area (usually the longitudinal axis of the cross is shorter in Rhysium ); and 2) the elytra could be distinctly pubescent in some species of Rhysium , as for example in R. bimaculatum , although usually distinctly shorter than in B. separatum .

When the second species was included in the genus, B. falcatum ( Fig. 31–33 ), two features used in the original description of the genus should have been changed: elytral apex is variable in Brechmoidion (outer elytral apex not spiniform in B. falcatum ), and apices of meso- and metafemora not spiniform (triangular lobe with blunt apex in B. falcatum ). If Brechmoidion separatum is kept in this genus, it would make Brechmoidion synonymous with Rhysium . It is possible that Brechmoidion exicisifrons (Martins, 1960) ( Fig. 34–37 ) and B. falcatum Napp and Martins, 1985 are only extreme variations of Rhysium . However, this is not certain, so for the time being we prefer to keep Brechmoidion and Rhysium as distinct genera. We are, however, formally transferring B. separatum to Rhysium , based on the following:

1. Antennal tubercles not acute and elevated ( Fig. 29 ). Actually, they are very similar to those in Rhysium ( Fig. 38 ), whereas in Brechmoidion they are more acute and elevated ( Fig. 33, 36 ).

2. Central pronotal tubercle nearly absent ( Fig. 30 ). In Brechmoidion it is very distinct ( Fig. 37 ).

3. Elytra without thick, erect, white setae. In Brechmoidion they are present.

4. Apices of meso- and metafemora rounded and slightly projected ( Fig. 28 ). In Brechmoidion they are projected, forming at least a triangular lobe ( Fig. 32, 35 ).

Figures

Figures 27–38. Adult habitus and structures of Rhysium and Brechmoidion spp. 27–30, Rhysium separatum, paratype male: 27) Dorsal habitus. 28) Apex of metafemur. 29) Antennal tubercles. 30) Pronotum. 31–33, Brechmoidion falcatum: 31) Dorsal habitus, paratypefemale. 32) Apex of metafemur, paratype male. 33) Antennal tubercles, paratype male. 34–37, Brechmoidion exicisifrons, paratype male: 34) Dorsal habitus. 35) Apex of metafemur. 36) Antennal tubercles. 37, Pronotum. 38, Rhysium bimaculatum, male, antennal tubercles.