Rudiaeschna Ren and Guo, 1996

Li, Yongjun, Nel, André, Ren, Dong, Zhang, Binglan & Pang, Hong, 2011, A new Chinese Mesozoic dragonfly clarifies the relationships between Rudiaeschnidae and Cymatophlebiidae (Odonata: Aeshnoptera), Zootaxa 2802, pp. 51-57 : 52-55

Genus Rudiaeschna Ren and Guo, 1996

Type species. Rudiaeschna limnobia Ren and Guo, 1996

Type locality and horizon. Huangbanjigou Village , Beipiao City , Liaoning Province, Northeastern China. Yixian Formation .

Emended diagnosis. Bechly et al. (2001) proposed an emended diagnosis for Rudiaeschna . We add the following important characters of the body structure and slightly modify the characters of wing venation: A pair of symmetrically expanded and rounded lobes on abdominal segment III (highly likely to be present only in male); with a row of small spines along distal two third of exterior margin of these lobes; abdominal segment II distinctly constricted. Cerci foliate, apically rounded and without spine at their apex; inferior appendage (epiproct) broad and long, about rectangular in shape, and apically slightly bifid. Despite the fact that the anal loop of Rudiaeschna is much more distinct and broader than in Cymatophlebia , its posterior closure is rather variable, from completely opened to weakly closed; no distinct gap of antesubnodal cross-veins between RA and RP close to arculus.

Description. Male CNU-ODO-LB2010001 Forewing hyaline, pterostigma dark brown; preserved wing length 47.8 mm, 12.9 mm wide; distance between base and arculus 5.0 mm, between arculus and nodus 18.9 mm; distance from nodus to mid pterostigma 17.1 mm, to wing apex 23.4 mm; distance between Ax1 and Ax2 4.8 mm, between Ax1 and wing base 4.1 mm; nineteen secondary antenodal cross-veins, four between Ax1 and Ax2; Ax2 lies at level of middle of discoidal triangle; arculus angular; pterostigma elongate and narrow, 4.5 mm long and 0.8 mm wide, covering four cells, not basally recessed; pterostigmal brace strong, well aligned with basal side of pterostigma, moderately oblique; 15 postnodal cross-veins not aligned with 13 postsubnodal cross-veins; median space free; submedian space only traversed by CuP-crossing and one distal cubito-anal cross-vein above PsA; PsA strongly zigzagged; hypertriangle with two oblique and weak cross-veins; discoidal triangle elongated, six-celled; MAb straight, about 4.7 mm long; a well-defined subdiscoidal triangle, three-celled in left, but four-celled in right forewing; base of IR2 5.1 mm basal of nodus; that of RP3/4 7.3 mm basal of nodus; nine cross-veins between RP and IR2 basal of first oblique vein ‘O’, including seven Bqs; first oblique vein ‘O’ about 1.7 mm distal of subnodus and second one five cells distally; pseudo-IR1 very short, originating from RP1 below distal side of pterostigma; area between RP1 and RP2 rather narrow with two-three rows of cells between them; base of RP2 well aligned with subnodus, RP2 smoothly undulated in its mid part; IR2 only slightly undulated, area between it and RP2 strongly widened at their undulated parts, with four rows of cells in its broadest part; IR2 and RP2 basally parallel, with only one row of cells; a well-developed and strongly curved Rspl with three rows of cells between it and IR2; two convex oblique and undulating secondary veins anastomosing between IR2 and RP3/4 directly basal of origin of Rspl; RP3/4 and MA parallel and smoothly undulated, with one row of cells between them basally and two rows of cells distally at their preserved length; MA and MP are more or less parallel, postdiscoidal area weakly widened at level of nodus; a very short and weak Mspl, few cells long; MA and CuA basally parallel with one row of rectangular cells between them, distally strongly divergent with at least two intercalary veins originating from MP; CuA with seven posterior branches, cubito-anal area with seven rows of cells between CuA and posterior wing margin; two rows of cells in anal area; a very short subdiscoidal veinlet, 0.2 mm long.

Hind wing hyaline, pterostigma dark brown; preserved wing length 45.0 mm, 16.3 mm wide; distance between base and arculus 5.3 mm, between arculus and nodus 15.4 mm; distance from nodus to mid pterostigma 19.0 mm; distance between Ax1 and Ax2 6.5 mm, between Ax1 and wing base 3.9 mm; thirteen secondary antenodal crossveins, five between Ax1 and Ax2; Ax2 lies slightly distal of distal angle of discoidal triangle; arculus angular; pterostigma elongated and narrow, 5.4 mm long and 0.9 mm wide, covering five cells, not basally recessed; pterostigmal brace slightly oblique and just basal of basal side of pterostigma; 15 postnodal cross-veins not aligned with 14 postsubnodal cross-veins; median space free of cross-veins; submedian space only traversed by CuP-crossing and one distal cubito-anal cross-vein above PsA; PsA strongly zigzagged; hypertriangle with two oblique and weak cross-veins; discoidal triangle elongated, divided into five cells; MAb straight, about 4.5 mm long; a welldefined three-celled subdiscoidal triangle; base of IR2 4.8 mm basal of nodus; that of RP3/4 6.2 mm basal of nodus; five cross-veins between RP2 and IR2 basal of the first ‘O’, and all cross-veins are Bqs; two oblique veins ‘O’, about 0.7 mm and 5.3 mm distal of subnodus, second ‘O’ much more oblique than first one; pseudo-IR1 not preserved; area between RP1 and RP2 rather narrow with two-three rows of cells between them; base of RP2 well aligned with subnodus, RP2 smoothly undulated at its mid part; IR2 weakly undulated, area between it and RP2 widened at their undulated parts; IR2 and RP2 basally parallel, with only one row of cells widening to three rows distally; a well-developed and strongly curved Rspl with three rows of cells between it and IR2; three convex oblique and undulating secondary veins anastomosing between IR2 and RP3/4 directly basal of origin of Rspl; RP3/4 and MA parallel and slightly undulated, with one row of cells between them basally and more than four rows of cells distally; MA and MP more or less parallel, postdiscoidal area weakly widened at level of nodus; a very short and weak Mspl, few cells long; two longitudinal intercalary veins between MA and MP; area between MP and CuA with two rows of cells basally and distally strongly divergent, with at least two intercalary veins originating on MP; CuAa with six well-defined and parallel posterior branches; CuAb directly towards posterior wing margin; anal loops weakly defined, posteriorly opened in left wing and closed with nine cells in right wing; gaff (basal part of CuA) elongated, 2.1 mm long; a very short subdiscoidal veinlet, 0.3 mm long but distinct; wing base with a distinct anal angle and a three-celled anal triangle (male specimen).

FIGURE 5. Detail photograph of specimen CNU-ODO-LB2010001, cerci. Scale bar: 2 mm.

Body: total body length (from head to end of abdomen, including anal appendages) 83.6 mm. Head 5.8 mm long, 6.2 mm wide, with compound eyes large, medially contiguous; thorax 7.7 mm wide with traces of coloration; fore legs partly preserved, tibia 5.4 mm long, tarsi three-segmented, 3.1 mm long, femur about 2.8 mm long; abdomen 65.9 mm long, 4.0 mm wide; first abdominal segment 2.7 mm long, second 11.4 mm long, third 9.8 mm long; second segment distinctly constricted with a width of 2.1 mm, no auricles visible on second segment; a pair of symmetrical expanded and rounded lobes on abdominal segment III, 6.0 mm long and 5.1 mm wide, with a row of small spines along the distal two third of exterior margin of these lobes; cerci clearly visible, foliate, 4.3 mm long and 1.0 mm wide, apically rounded and without spine at their apex; inferior appendage (epiproct) broad (2.9 mm) and long (1.5 mm), about rectangular in shape, and apically slightly bifid; genitalia can be discerned with anterior lamina (AL), posterior lamina (PL), anterior hamule (AH), posterior hamule ( PH), cleft of the anterior lamina (CAL), sheath of the penis (SHP) and penis ( Fig. 2, 3, 4, 5).