Epilestes rasnitsyni, FELKER & VASILENKO, 2021

FELKER, ANASTASIA & VASILENKO, DMITRY, 2021, A new species of the ʻprotozygopteranʼ damselfly (Odonata: Permagrionidae) from the Lower-Middle Permian of Russia, Palaeoentomology 4 (5), pp. 462-467 : 463-466

Epilestes rasnitsyni sp. nov.

( Figs 1–3 )

Material. Holotype specimen GGM-1844-02/BP-12885, imprint of a body in profile with legs, forewings and one hindwing not attached. Holotype deposited in the Vernadsky State Geological Museum , Russian Academy of Sciences, Russia .

Etymology. The specific name honours Professor Alexander P. Rasnitsyn, on his 85 th birthday.

Diagnosis. Forewings: wing long and wide in middle part; strongly petiolate; Ax2 strongly basal of Arc. Five Pn and six or seven Psn. Pt trapezoidal, three underlying in interradial-area (between IR1 and RP1) cells long; mcu lying distal of MAb; AA independent in basal half of petiole; cubital area broad, with one-supplement row of cells between CuA and posterior wing margin.

Locality and horizon. Mogilnikovo (Vishera), Cherdynsky District, Perm Territory; Solikamsk Formation, Solikamsk horizon; Ufimian Stage, Russia.

Description. Head in semi-profile position. Head is medium-sized, 5.5 mm long, 3.3 mm wide, with relatively small elliptical compound eyes, about 3.6 × 2.1 mm. Frons 2.8 × 0.9 mm, ocelli not visible. Antennae not preserved, mouthparts orthognathous, mandibles triangular, 1.7 mm long.

Thorax in profile. Prothorax is medium-sized; 4.1 mm long; part of prothorax is covered by a head. Pterothorax is strong, zygopteroid shape; mesopleural (msst) and metapleural (mtst) sutures are well distinguished and complete, msst 7.6 mm long, mtst 6.3 mm long; mesothorax 7.9 mm long, 3.4 mm wide, with visible mesipesternum and mesepimeron; metathorax with three distinguishable segments; metepisternum elongate, with rounded edges, 8.4 mm long, 2.6 mm wide; mesepimeron elongate, 7.0 mm long, 1.7 mm wide; the 3 rd thorax sternite is poorly preserved, 3.4 mm long, 1.0 mm wide. Thorax skewness is pronounced (angle x – 43°; angle z – 44° sensu Needham & Anthony (1903)).

Legs of moderate length. Coxa not visible; trochanter preserved only on the left hind leg, 3.1 mm long, 0.9 mm wide; femora and tibiae are elongate, with equal length (about 5.0 mm), but the former are 3 times wider than the latter (1.5 mm and 0.5 mm respectively). Tarsi narrow and long, about 3.2 mm long, 0.3 mm wide, with two very strong claws; individual tarsal segments are poorly visible.

Abdomen in dorsal semi-profile, with six basal segments preserved. Lateral carina is clearly visible on 2–4 segments. The ratio of visible parts of sternite to tergite is 1 to 3. No trace of specialized genital structures on visible parts of the second and the third segments. Preserved part of abdomen is about 40.5 mm long, 3.9–5.1 mm wide. First segment shorter than others, 2.3 mm long, 5.1 mm wide.

Right forewing complete ( Fig. 3 ). Wing length 42.3 mm, width at level of N 5.5 mm, maximum width, at level of base of IR3 6.8 mm; length from wing base to Arc 6.5 mm, from Arc to N 9.0 mm, from N to Pt 19.7 mm, from Pt to wing apex 3.5 mm. Two visible antenodal crossveins preserved, distance from wing base to Ax1 2.5 mm, from Ax1 to Ax2 1.8 mm, Ax2 2.0 mm basal of Arc. Subantenodal cross-vein (ASn), slightly oblique, oriented towards wing base, lying 9.9 mm distal of wing base and 5.0 mm basal of N. Nodus at basal third (about 37%) of wing length. Nodal structures strongly oblique, aligned with each other, Cr is half as long as Sn. Five postnodal crossveins not aligned with seven postsubnodal crossveins present in costal area between N and Pt. Two oblique postnodal crossveins not aligned with three postsubnodal crossveins lying distally Pt. Pt elongate and trapezoidal, thickened at the middle (maximum width, at the level of Pt brace 0.5 mm); costal side longer than others, 3.9 mm long; posterior (pterostigmal part of RA) side 3.3 mm long, basal part oblique, 0.3 mm long, distal part very oblique, 0.6 mm long. Pterostigmal brace oblique, oriented towards wing base, lying 1.4 mm distal of Pt base.

Petiole long and narrow; dc basally opened, elongate, distal edge of dc (MAb) 0.7 mm long. Subdiscoidal cell triangular, elongate, slightly curved; anterior part of Sdc 2.8 mm long, posterior part of Sdc 3.3 mm, distal edge (m-cu crossvein) 0.6 mm long. MAa and MAb separated 6.9 mm from base of RP; MAb 0.7 mm long; MP and CuA bifurcating opposite separation of RP and MA; AA independent, separated from AP at wing base, and ending in petiole 3.6 mm distal of wing base. CuP not visible in petiole.

Base of RP 1.3 mm distal to arculus; base of RP3/4 0.3 mm distal of Sn and 8.6 mm distal of base of RP; base of IR2 15.0 mm distal of RP origin, and 6.5 mm and two cells distal of base of RP3/4. Base of RP2 20.7 mm distal of RP origin, and 5.7 mm and three cells distal base of IR2. Base of IR1 25.2 mm distal of RP origin, 4.5 mm and three cells distal of base of RP2, 1.4 mm and one cell basal of Pt base. All radial and intercalary longitudinal veins are simple and straight, without visible longitudinal supplementary veins between them. Endings of radial and intercalary veins lying distal of Pt. MAa very weakly zigzagged in distal half, ending of MAa 4.5 mm basal of wing apex. MP simple and straight, ending 6.4 mm basal of wing apex, and 1.9 mm and three cells basal of ending of MAa. CuA weakly zigzagged and long, ending of CuA 12.0 mm basal of wing apex, and 5.7 mm and nine cells basal of ending of MP. Cubital area with one supplement row of cells on two thirds of its length.

Left forewing incomplete, wing base and apex not preserved. The length of preserved part 33.5 mm, width at level of N 5.3 mm, maximum width, at level of base of IR3 6.6 mm; length from N to Pt 20.1 mm.

Subantenodal cross-vein (ASn), slightly oblique, lying 4.2 mm basal of N. Cr aligned with Sn, Sn with stronger obliquity than Cr. Five postnodal crossveins not aligned with six postsubnodal crossveins before Pt. Only one visible postnodal crossveins not aligned with two postsubnodal crossveins present distal of Pt. Pt elongate and trapezoidal, maximum width, (in the distal quarter 0.5 mm); costal side 4.1 mm long; posterior (radial) side 3.3 mm long, basal part oblique, 0.4 mm long, distal part oblique, 0.6 mm long. Pterostigmal brace of inverted obliquity, lying 1.7 mm distal of Pt base.

Only distal parts of dc and Sdc preserved on indicated wing. Very oblique distal edge of dc (MAb) 1.0 mm long. Subdiscoidal cell slightly curved and elongate, with distal edge (concave m-cu crossvein) 0.8 mm long. MAa and MAb bifurcating 5.7 mm basal of N.

Base of RP3/4 0.6 mm distal of Sn; base of IR2 6.3 mm and two cells distal of base of RP3/4, and 7.1 mm distal of Sn. Base of RP2 5.6 mm and three cells distal base of IR2, and 12.7 mm distal of Sn. Base of IR1 4.4 mm and three cells distal of base of RP2, and 17.1 mm distal of Sn, 1.0 mm and one cell basal of Pt base. No visible longitudinal supplementary veins between main radial and intercalary veins. RP1 and RP2 long and straight. IR1 and IR2 very weakly zigzagged in distal part. Ending of RP3/4 lying 1.2 mm and one cell distal of Pt edge. MAa and MP long and straight. Between endings of RP3/4 and MAa 2.5 mm and four cells; between the endings of MAa and MP 1.5 mm and three cells. Ending of MP lying at the level of basal edge of Pt. CuA very weakly zigzagged and long, ending of CuA 4.1 mm and eight cells basal of ending of MP. Cubital area with one row of cells to the level of N, with two rows more distally between level of N and the fourth postsubnodals, and again with one row near ending of CuA.

Left hindwing is poorly preserved and strongly deformed. The length of preserved part 31.6 mm, width at level of proximal edge of Pt 4.7 mm; Pt trapezoidal and elongate, with basal and distal edges of different obliquity. The length of the longest costal edge 4.3 mm, posterior (radial) edge 4.0 mm, maximum width of Pt 0.5 mm.

Figures

FIGURE 1. Epilestes rasnitsyni sp. nov., holotype GGM-1844-02/BP-12885. Photograph of habitus. Scale bar = 10 mm.

FIGURE 2. Epilestes rasnitsyni sp. nov., holotype GGM-1844-02/BP-12885. Tracing of impression; S1–S6 = segments of abdomen, msst = mesopleural suture, mtst = metapleural suture. Scale bar = 10 mm.

FIGURE 3. Epilestes rasnitsyni sp. nov., holotype GGM-1844-02/BP-12885. Tracing of right forewing; Scale bar = 5 mm.