Geraeus coarctatus Champion

Prena, Jens, 2009, A Review of the Species of Geraeus Pascoe and Linogeraeus Casey Found in the Continental United States (Coleoptera: Curculionidae: Baridinae), The Coleopterists Bulletin 63 (2), pp. 123-172 : 140

Geraeus coarctatus Champion

( Figs. 19, 20 , 58 , 72 )

Geraeus coarctatus Champion 1908:281 . Syntypes, 2 females (BMNH), examined by C. W. O’Brien.

Recognition. Geraeus coarctatus is a 4.7–6.7 mm long, robust species with inconspicuous vestiture. The morphology and regionally restricted occurrence make it a distinctive species in the United States. However, at least five similar species occur in Mexico, of which G. pannuceus radiates into southern Arizona. Geraeus coarctatus can be distinguished from most of them by the subtle pronotal sculpture, the short second desmomere, and the tubercle on the submentum of the male; the basal sclerite of the aedeagus is also highly diagnostic ( Fig. 58 ).

Distribution. The species occurs in central Mexico and reaches the United States in southern Arizona ( Fig. 72 ).

Type locality. Mexico .

Temporal occurrence. August to November [9 dates].

Plant associations. Commelina sp. (O’Brien, observation), Commelina dianthifolia Delile (P. Sullivan, C. W. O’Brien, J. Prena, observations).

Material examined. United States: Arizona ( CWOB 25 , JPPC 17 ) . Mexico: Durango ( CWOB 4 , TAMU 1 ), Hidalgo ( CWOB 2 ) , Mexico ( CWOB 1 ) , San Luis Potosí ( TAMU 1 ) , Sonora ( CWOB 13 ) . Total 64 specimens .

Note. Geraeus coarctatus is newly recorded for the United States. The relatively late appearance in the year combined with the regionally restricted occurrence may explain why this large species has been overlooked for such a long time. The first specimen was collected in Coronado National Memorial in 1965. The species has been collected in numbers following Pat Sullivan’s recent discovery of its association with Commelinaceae .

Figures

Figs. 17–24. Geraeus species, dorsal and lateral aspects; scale bar 1 mm. 17, 18) G. modestus, male; 19, 20) G. coarctatus, male; 21, 22) G. pannuceus, male; 23, 24) G. patagoniensis, female.

Figs. 57–60. Geraeus and Linogeraeus species, aedeagus, dorsal aspect; scale bars

Figs. 71–72. Map of United States (without northwestern part) and Central America showing distributions of G. coarctatus, G. modestus, G. penicillus, and G. picumnus.