Epiaeschna Hagen, 1875
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publication ID |
https://doi.org/ 10.5252/z2011n4a8 |
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persistent identifier |
https://treatment.plazi.org/id/03F2BF4D-3251-B817-FC99-2D1AFDB7F916 |
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treatment provided by |
Felipe |
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scientific name |
Epiaeschna Hagen, 1875 |
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Genus Epiaeschna Hagen, 1875 View in CoL
TYPE SPECIES. — Aeshna heros Fabricius, 1798 (recent).
OTHER SPECIES. — Epiaeschna pseudoheros Nel & Petrulevičius, 2010 (late Oligocene, France), Epiaeschna stauropolitana Martynov, 1927 (middle Miocene, Crimea), Epiaeschna magnifica (Martynov, 1929) (late Oligocene, Kazakhstan), Epiaeschna gossi (Campion, 1916) (middlelate Eocene, UK), Epiaeschna matutina ( Zhang, 1989) (middle Miocene, China).
Epiaeschna matutina ( Zhang, 1989) ( Figs 2-9 View FIG View FIG View FIG View FIG View FIG View FIG View FIG View FIG )
MATERIAL. — Four well preserved specimens: No. CNU-ODO-SS2011007 (print of thorax with nearly complete left wings and overlapped right wings), No. CNU-ODO-SS2011008 (print of a nearly complete right forewing plus two hindwings with apices missing), No. CNU-ODO-SS2011009 (print and counterprint, thorax with attached partly overlapped right wings and left wing bases), and No. CNU-ODO-SS2011010 (print of a complete hindwing). All specimens deposited at the College of Life Science, Capital Normal University, Beijing, China.
AGE AND OUTCROP. — Shanwang Formation, Middle Miocene. Shanwang Village, Linqu County, Shandong Province, China.
EMENDED DIAGNOSIS. — Wings uniformly sandy beige coloured; anal membranule strongly reduced; forewing arculus angled, sectors of arculus arising near its lower end, result in a prolonged anterior part; anal loop relatively enlarged (generally divided into about twelve cells, but nine cells in No. CNU-ODO-SS2011009); male anal triangle three-celled; forewing primary antenodal bracket Ax1 and Ax2 are oblique (Ax1 more oblique than Ax2), while hindwing has its Ax1 and Ax2 nearly perpendicular.
REMARK
The type specimen of this species is based on a thorax with fragments of legs and abdomen plus four wings with median portions partly destroyed. Several characters were unknown for this species. The original description and figure of Zhang (1989: 32-33, fig. 14) are relatively poor. Thanks to the present discovery, we can complete the diagnosis and description.
REDESCRIPTION
Wings uniformly sandy beige coloured; pterostigma dark brown.
Forewing (mainly based on specimen No. CNU- ODO-SS2011008, left forewing). Wing 55.5 mm long, 12.4 mm wide at level of nodus; distance from wing base to Ax1 3.7 mm, to Ax2 9.7 mm, to arculus 5.8 mm, to nodus 27.3 mm; distance from nodus to base of pterostigma 17.0 mm, to level of bifurcation of IR2 12.4 mm; pterostigma 5.5 mm long and 0.8 mm wide, covering five cells; pterostigma brace oblique, well aligned with basal side of pterostigma; Ax1and Ax2 oblique (Ax1 more oblique), with six secondary antenodal crossveins and four or five antesubnodal crossveins between them; 19 secondary antenodal crossveins not aligned with 18 antesubnodal crossveins distal of Ax2; 21 postnodal crossveins not aligned with 18 postsubnodal crossveins; arculus angled, sectors of arculus arising near its lower end, resulting in a prolonged anterior part; IR1 originating from RP1 nearly at level of basal fourth of pterostigma, with three to four rows of cells between it and RP1; RP1 and RP2 strictly parallel to level of pterostigma, with one row of cells in between; RP2 evenly curved toward posterior wing margin at level of pterostigma; anterior branch of IR2 more or less parallel with RP2 with only one row (rarely two rows) of cells between them, area between them distally constricted; IR2 symmetrically forked, 4.2 mm basal of level of basal side of pterostigma, five to seven rows of cells in area between forks of IR2; Rspl nearly straight, area between Rspl and posterior branch of IR2 with three rows of cells in its widest part, constricted and with only one row of cells distally; RP3/4 and MA parallel, with one row of cells in between, but two rows of cells distally; one oblique vein “O” slightly distal of base of RP2; Mspl slightly curved, area between Mspl and MA with three rows of cells in widest part, but distally constricted and with two rows of cells; MP smoothly curved; CuA with five posterior branches; area between MP and CuA with only one row of cells; median space free; submedian space crossed by six crossveins, including strong CuP; PsA not stronger than other crossveins in submedian space, so no well defined subdiscoidal triangle; hypertriangle very elongated, 9.0 mm long, seven-celled; discoidal triangle elongated, 6.7 mm long and 1.9 mm wide (basal side 2.3 mm and costal side 7.4 mm long), nine-celled; convex trigonal planate in postdiscoidal area basally straight during four cells and distally zigzagged; anal area with two to three rows of cells.
Hindwing (mainly based on specimen No. CNU- ODO-SS2011007 left hindwing). Wing 55.6 mm long, width at level of nodus 17.2 mm; distance from wing base to Ax1 4.1 mm, to Ax2 9.3 mm, to arculus 5.9 mm, to nodus 23.2 mm; distance from nodus to base of pterostigma 19.1 mm, to wing apex 32.4 mm, to level of fork of IR2 14.0 mm; pterostigma 6.2 mm long and 0.8 mm wide, covering five cells; pterostigma brace oblique, well aligned with basal side of pterostigma; Ax1 and Ax2 straight and nearly perpendicular to ScP, with three secondary antenodal and antesubnodal crossveins between them; 14 secondary antenodal crossveins not aligned with 13 antesubnodal crossveins distal of Ax2; 22 postnodal crossveins not aligned with 18 postsubnodal crossveins; arculus angled, sectors of arculus arising near its middle; base of IR1 at level of basal side of pterostigma, with two to three rows of cells between it and RP1; RP1 and RP2 strictly parallel to level of pterostigma, with one row of cells in between; RP2 and anterior branch of IR2 parallel with only one row of cells between them, area between them distally constricted; RP2 smoothly bent toward posterior wing margin at level of basal side of pterostigma; IR2 is symmetrically forked, 5.1 mm basal of basal side of pterostigma, four rows of cells in area between forks of IR2; Rspl nearly straight, area between Rspl and posterior branch of IR2 with three rows of cells in widest part, but distally constricted and with only one row of cells; RP3/4 and MA parallel, with one row of cells in between, but two rows of cells distally; one oblique vein “O” slightly distal of base of RP2; Mspl slightly curved, area between Mspl and MA with three rows of cells in widest part, but distally constricted and with two rows of cells;MP shortened,ending on posterior wing margin at level of nodus; CuAa with five posterior branches; area between MP and CuAa with only one row of cells basally, but expanded with three or four rows of cells distally; median space free; submedian space crossed by four crossveins, including CuP; CuP-crossing strong; PsA not stronger than other crossveins in submedian space, so no well defined subdiscoidal triangle; hypertriangle elongated 8.3 mm long, but apparently shorter than in forewing, fivecelled; discoidal triangle elongated, 6.6 mm long and 2.2 mm wide (basal side 2.5 mm and costal side 7.1 mm long), six-celled; convex trigonal planate in postdiscoidal area basally straight during three cells and distally zigzagged; anal loop large, pentagonal, transversely elongated, twelve-celled; gaff rather long and straight, 1.9 mm long; basal side of anal loop straight and long, about 5.5 mm long; anal triangle well defined, narrow and three-celled with its basal side slightly curved; membranule strongly reduced; anal angle well defined.
COMPARISON WITH OTHER EPIAESCHNA SPECIES Nel & Petrulevičius (2010) synonymized Mediaeschna Zhang, 1989 (type species M. matutina Zhang, 1989 ) with Epiaeschna Hagen, 1873 . These new fossils are very similar to the holotype of Epiaeschna matutina ( Zhang, 1989) . They confirm the generic identity of Mediaeschna with Epiaeschna . Moreover, all come from the same locality. Significant differences are as follows: 1) our new fossils are smaller, i.e. wing length of about 55-59 mm vs 64 mm in holotype of E. matutina ; 2) area between MP and CuA has only one row of cells up to level of nodus and is distally expanded in both pairs of wings vs basally two rows of cells and distally constricted in holotype of E. matutina . We provisionally consider that these differences are related to intraspecific variations and are not sufficient to support a species separation. But this causes a difficulty in the separation of E. matutina from some other species of Epiaeschna .
Epiaeschna stauropolitana Martynov, 1927 and E.magnifica (Martynov,1929) have pterostigmata covering much more cells than in other Epiaeschna species , including E. matutina . Nel et al. (2010) proposed the following characters to distinguish E. matutina from the other species in Epiaeschna : “ Epiaeschna matutina differs from E. heros in its pterostigma covering 6-7 cells, with a more oblique brace, discoidal triangle with 7-8 cells, instead of 4-6 in E.heros .”The number of cells covered by the pterostigma no longer stands because the new specimens of E. matutina have only five cells covered by pterostigma. Nevertheless, the number of cells in discoidal triangle is still valid.
Nel & Petrulevičius (2010) added: “ E. matutina apparently differs from E. gossi (Campion, 1916) in the less numerous postnodal cross-veins but a new description of the forewings of the two species would be necessary to precise the differences between them”. The new material confirms that E. gossi has much more postnodal crossveins in forewing (31-33) than E. matutina (21). Another difference is Ax1 and Ax2 not distinctly oblique in forewing of E.gossi , unlike in E. matutina (see Jarzembowski 1996: pl. 2, fig. 1).
Lastly, Nel & Petrulevičius (2010) indicated that E. pseudoheros Nel & Petrulevičius,2010 “differs from E. matutina in its pterostigma covering less number of cells (six in E. matutina ), and hindwing discoidal cells divided into less cells”. The first difference no
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longer stands, but the second one is confirmed by the present study. Th e trigonal planate is also longer in E. matutina than in E. pseudoheros .
One further aspect that could be important for the species diagnosis is the wings uniformly sandy beige coloured in E. matutina (present in both the holotype and our new fossils). This character remains only of partial use because the exact wing coloration is unknown for several other species of Epiaeschna ( E. pseudoheros or E. stauropolitana ). It seems to be rather dark in distal half but more hyaline in basal half of forewing of E. gossi .
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