Review of Oxystigma Selys with the synonymy of Oxystigma williamsoni Geijskes (Odonata: Heteragrionidae) Author Garrison, Rosser W. text Zootaxa 2014 3780 2 347 364 journal article 46158 10.11646/zootaxa.3780.2.7 3aef331c-7a5e-48ba-8731-a93a3a993511 1175-5326 226134 72C52670-4454-46D3-8D71-9BC8E8A98434 Key to males of Oxystigma 1. Cercus in medio-dorsal view with supplementary denticulate ridge extending to basal 0.30 ( Figs. 41–42 ), transverse ridge present on medial lobe ( Figs. 41–42 ); distal portion of cercus beyond posterior margin of medial lobe short, about 0.30 of cercus ( Fig. 42 ; A> B); larger species, HW ≥24.0 mm; Sierra de Lema region, Bolívar State, Venezuela ( Fig. 58 )........ caerulans 1'. Cercus in medio-dorsal view with denticulate ridge extending to basal 0.50, transverse ridge absent on medial lobe ( Figs. 43– 57 ; vestigial in some O. petiolatum from Rondônia State, Brazil , Fig. 56 b); distal portion of cercus beyond posterior margin of medial lobe long, about ≥0.45 of cercus ( Fig. 43 ; A ≈ B); smaller species, HW ≤24.0 mm; widespread in northern and central South America ( Fig. 58 )................................................................................ 2 2(1'). Frons, clypeus and labrum light blue ( Figs. 2–3 ); synthorax in mature male largely black or dark brown above ( Figs. 17–18 ); cercus in dorsal view with transverse ridge prominent and not reaching posterior margin of medial lobe ( Figs. 49–51 )................................................................................................... cyanofrons 2. Frons, clypeus and labrum mottled with black spots on a pale blue or yellow underground or largely dark to shining black, ( Figs. 6–14 ); synthorax in mature male black or dark brown above, with pale dorsal or humeral stripes ( Figs. 21–23 ); cercus in dorsal view with transverse ridge extending posteriorly beyond medial lobe ( Figs. 52–54 ) or to medial lobe posterior margin ( Fig. 55 ) or (populations from Ecuador and Rondônia State, Brazil ) disappearing ventro-posteriorly, not forming a prominent ridge ( Figs. 56–57 )............................................................................ petiolatum