Dimeragrion unturanense, DeMarmels, 1992

DeMarmels, Jurg, 1992, Dragonflies (Odonata) From The Sierras Of Tapirapeco And Unturan, In The Extreme South Of Venezuela, Acta Biologica Venezuelica 14 (1), pp. 57-78 : 59

Dimeragrion unturanense sp. n.

Figures 8-10

Male (holotype). Venezuela, Amazonas State, Sierra de Unturan, 950 m, 01°25'N, 65°18'W, 15- 18 Feb 1989, J DEMARMELS leg . Material (5 ♂, 1 ♀, including holotype and paratypes). 1 ♂, paratype, same dates as holotype , 4 ♂, paratypes, Tamacuari .

Male (holotype). Labium dark brown, face brilliant black, a white transverse band across antedypeus and base of labrum; occiput and top of head black, a rufous streak between each lateral ocellus and corresponding antenna; frons angulate. Prothorax dorsally brassy black, its hind margin convexly rounded; pterothorax dark brown to black with metallic blue or green reflections; mesepisternum and mesepimeron densely covered with bluish pruinescence; some pruinosity also along sutures and ventrally. Legs dark brown to black. Wings slightly smoky, pterostigma dark brown. 23 (25) postnodal cross·veins (px) in fore wings 19 (20) in hind wings. 2 cubito-anal cross. veins (Cux) in three wings, 3 in left fore wing. 2 antenodal cells in discoidal field in all but in left fore wing (3). R4 originating very little before subnodus, IR, at first px. R3 branching after px 6 in fore wings, at px 6 in hind wings; IR2 originating at px 11 in fore wings, in hind wings at or after px 9. Abdomen dark brown to black; segments 3-6 with a brown basal ring; segments 1,2 and 9 with blue pruinescence dorsally. Superior anal appendages slightly shorter than segment 10 and triangularly pointed in lateral view (Fig. 8) in dorsal view tips convergent (Fig. 9). Penis similar to D. mesembrinum DeMarmels ( DEMARMELS, 1989b: Figs. 4-5 ).

Measurements. Tctal length (excl. anal appendages) 38.0; abdomen (excl. anal app.) 30.5; anal appendages 0.8; hind wing 35.2; pterostigma (costal side, front wing) 1.0; radial side 2.0.

The paratype males do not differ substantially from the holotype: 3-4 antenodal cells in the discoidal field; minor variations in the branching of IR2 and R3; R4 often originating slightly more proximally. Measurements. Total length (excl. appendages) 40.5-43.5.

Female (paraytpe). Labium pale; pale transverse band across face also including mandibles and genae. Prothorax as in male. Pterothorax brown whith cooppery reflections and yellowish stripes along humeral and lateral sutures. Wings smoky, pterostigma brown. 24(25) px in fore wings, 21 (22) in hind wings. Only 2 antenodal cells in the discoidal field; 2-3 cux. R3 originating after px 7 in three wings, after px 8 in left fore wing; IR2 branching at px 12 (10) in fore wings, at px 9(11) in hind wings. R4 originating more proximally from subnodus than in the holotype. Abdomen brown; cerci two times the length of segment 10 (Fig. 10) .

Measurements. Total length (excl. anal appendages) 31.5; abdomen (excl. app.) 25.0.

Remarks. Male D. unturanense differ from male D.mesembrinum, D. percubitale Calvert and D. secundum Needham in having shorter, triangularly pointed superior anal appendages (lateral view) with the basal dorsal tubercle higher than tergal surface of segment 10. Tips of inferior appendages strongly curved upwards and slightly cephalad. The female of D. secundum is unknown, but probably' differs from D. unturanense in color pattern of head and in having only one cux. Female D. unturanense have the dorsobasal tubercle of the cerci slightly better developed female D. percubitale and D. mesembrinum . The latter has only one cux in all wings. At both localities D. unturanense was taken along small creeks in the forest together with Iridictyon trebbaui and (larvae of) Neocordulia biancoi Racenis (see below).

Figures

Plate II: Figure 7. Chalcopteryx scintillans, female ultimate instar exuviae, labium, ventral view. Figures 8-10. Dimeragrion unturanense sp.n. (8) holotype male, abdominal segment 10 with anal appendages, left lateral view; (9) same, dorsal view; (10) female, paratype, tip of abdomen, left lateral view. Figure3 11-12. Megapodagrion megalopus, male. (11) penis, ri.ght lateral view; (12) same, ventral view. Figures 13-14. Allopodagrion oscillans (Venezuela, Tachira, Betania). male. (13) penis, right lateral view; (14) same, ventral view.

Plate I: Figures 1-6. Iridictyon trebbaui, larva. (1) male larva. ultimate instar, dorsal view; (2) right antenna; (3) labium, dorsal view; (4) abdominal segments 9 (with gonapophyses) and 10, ventral view (all same specimen); (5) female larva ¿.ante?) penultimate instar, detached lateral gill; (6) median gill, left lateral view (same specimen).