Elektrogomphaeschna peterthieli, Pinkert, Stefan, Bechly, Günter & Nel, André, 2017

Pinkert, Stefan, Bechly, Günter & Nel, André, 2017, First record of hawker dragonflies from Eocene Baltic amber (Odonata: Anisoptera: Gomphaeschnidae), Zootaxa 4272 (2), pp. 263-275 : 264-268

Elektrogomphaeschna peterthieli sp. nov.

( Figs. 1–4 )

Material. Holotype SMNS BB- 2390 and paratype SMNS BB- 2825 , stored in the collection of the state Museum of Natural History Stuttgart in Germany .

Etymology. Named in honour of Mr. Peter Thiel (San Francisco, USA) for his generous support of the research of the second author.

Age and outcrop. Eocene (most probably Middle-Upper Eocene, Lutetian to Bartonian or Priabonian, Standke, 2008), Baltic amber.

Diagnosis. Distinguished from the only other species E. annekeae sp. nov. by the distinctly smaller size (forewing length only 27–31 mm instead of about 43 mm), correlated with smaller number of postnodal crossveins (12 instead of 15); Ax 2 in more basal position at level of basal of triangle or even somewhat basal of triangle (instead of level of middle of triangle); origin of Mspl separated by four cells (instead of three cells) from distal angle of triangle.

Description. Holotype SMNS BB-2390 ( Figs. 1–2 ): An isolated right pair of wings, with a complete forewing and distal half of hindwing. Forewing hyaline, 27.3 mm long; 6.6 mm max width; from arculus to nodus 8.3 mm; from nodus to pterostigma 11.7 mm. Pterostigma short (1.6 mm long and 0.5 mm wide), covering two cells, and strongly braced by a very oblique (but straight) crossvein aligned with its basal side. Twelve postnodal crossveins between nodus and pterostigma, not aligned with corresponding postsubnodal crossveins between RA and RP1. Primary antenodal Ax1 1.8 mm basal of arculus, and primary antenodal Ax2 only 0.9 mm distal of arculus on level of ventral angle of triangle; a single non-aligned secondary antenodal between Ax1 and Ax2; six non-aligned secondary antenodal crossveins between Ax2 and nodus. ScP fusing with costal margin at nodus, of normal anisopteran-type. Antesubnodal area hardly visible. Discoidal triangle two-celled, very elongated with a slightly bent distal side MAb; length of anterior side 2.6 mm; of basal side 1.0 mm; of distal side MAb 2.5 mm. Hypertriangle poorly visible (because of restricted viewing angle), but apparently free and 3.2 mm long. Several antefurcal crossveins between RP and MA basal of midfork (3 visible). Two bridge crossveins basal of subnodus. Base of RP2 aligned with subnodus. Only a single oblique vein ‘O’, one cell distal of subnodus. A long and nearly straight Rspl, parallel to IR2 with only a single row of cells between it and IR2; two convex secondary veins visible in area between Rspl and RP3/4. IR2 only gently curved. RP2 and IR2 begin to diverge somewhat basal of pterostigma with 2–3 rows of cells in widened area between these two veins. RP2 weakly curved but not undulated. RP2 and RP1 only slightly diverging basally with only a single row of cells in area in-between, but 2.5 cells basal of pterostigma they become divergent with two or more rows of cells. Well-defined long and nearly straight IR1 closely parallel to RP1 with only a single row of cells in-between. RP3/4 and MA parallel and gently curved with only a single row of cells in-between, except for a short area with two rows of cells near posterior margin of wing. Mspl long, straight, and parallel to MA with a single row of cells in-between. Postdiscoidal area basally with two rows of cells, but distally strongly widened (width near discoidal triangle 1.1 mm). MP ending distal of nodus. Cubital area not preserved.

Hindwing hyaline, basal half missing; preserved part 17.9 mm long; 6.7 mm max width near nodus. Pterostigma short (1.6 mm long and 0.6 mm wide), covering three cells, and strongly braced by a very oblique (but straight) crossvein that is aligned with its basal side. Ten postnodal crossveins between nodus and pterostigma, poorly aligned with corresponding postsubnodal crossveins between RA and RP1. Base of RP2 aligned with subnodus. Only a single oblique vein ‘O’, less than one cell distal of subnodus. A long and slighly bulged Rspl, parallel to IR2 with only a single row of cells between it and IR2; two convex secondary veins visible in area between Rspl and RP3/4. IR2 only gently curved. RP2 and IR2 begin to diverge somewhat basal of pterostigma with 2–3 rows of cells in widened area between these two veins. RP2 weakly curved but not undulated. RP2 and RP1 only slightly diverging basally with only a single row of cells in area in-between, but 5 cells basal of pterostigma they become divergent with two or more rows of cells. Well-defined long and nearly straight IR1 closely parallel to RP1 with only a single row of cells in-between. RP3/4 and MA parallel and gently curved with only a single row of cells in-between, except for a short area with two rows of cells near posterior margin of wing. Mspl long, straight, and parallel to MA with a single row of cells in-between. Part of median area and all of cubital area not preserved.

Paratype SMNS BB-2825 ( Figs. 3–4 ): An incompletely preserved left pair of wings. Forewing with basal half mostly preserved, but of the distal half only a part of the postnodal and postsubnodal area is preserved. Wing hyaline, preserved part 23.3 mm long (estimated total length about 31 mm); from arculus to nodus 9.4 mm. Pterostigma not preserved. Nine postnodal crossveins preserved, not aligned with the corresponding postsubnodal crossveins. Primary antenodal Ax1 2.0 mm basal of arculus, and primary antenodal Ax2 only 0.5 mm distal of arculus and even slightly basal of triangle; a single non-aligned secondary antenodal between Ax1 and Ax2; eight non-aligned secondary antenodal crossveins between Ax2 and nodus. ScP fusing with costal margin at nodus, of normal anisopteran type. Antesubnodal area with 8 crossveins and a short gap directly basal of subnodus. Discoidal triangle two-celled, very elongated with a slightly bent distal side MAb; length of anterior side 2.9 mm; of basal side about 1.0 mm; of distal side MAb about 2.5 mm. Hypertriangle free (3.5 mm long, max. 0.4 mm wide). Subdiscoidal cell free; subdiscoidal vein not ending at basal angle of triangle. Five antefurcal crossveins between RP and MA basal of midfork. Base of RP2 aligned with subnodus. RP3/4 and MA parallel and gently curved with only a single row of cells in-between. Mspl long, straight, and parallel to MA with a single row of cells in-between. Postdiscoidal area basally with two rows of cells, but distally strongly widened (width near discoidal triangle 1.6 mm). MP ending distal of nodus. Cubital area not preserved.

Hindwing with only an anterobasal fragment preserved. Wing hyaline. Primary antenodal Ax1 2.0 mm basal of arculus, and primary antenodal Ax2 1.8 mm distal of arculus on the level of middle of triangle; two non-aligned secondary antenodals between Ax1 and Ax2; eight non-aligned secondary antenodal crossveins between Ax2 and nodus. ScP fusing with costal margin at nodus, of normal Anisoptera-type. Antesubnodal area with several crossveins (five preserved). Discoidal triangle two-celled and elongated; length of anterior side 2.9 mm, of basal side 1.1 mm, of distal side MAb about 2.7 mm. Hypertriangle free (3.2 mm long, precise width cannot be determined because of viewing angle). Subdiscoidal cell free; subdiscoidal vein not ending at basal angle of triangle. Five antefurcal crossveins between RP and MA basal of midfork.

Comment. Attribution of the paratype specimen to the same species as the holotype is based on the nearly identical wing venation in the preserved parts of both specimens and the only insignificant difference in size.

Figures

FIGURE 1. Elektrogomphaeschna peterthieli, holotype SMNS BB- 2390. A, drawing of forewing; B, drawing of hind wing (scale bars represent 2 mm).

FIGURE 2. Elektrogomphaeschna peterthieli, holotype SMNS BB- 2390. A, photograph of forewing (scale bar represents 2 mm); B, photograph of hind wing (scale bar represents 2 mm); C, photograph of forewing triangle (scale bar represents 1 mm).

FIGURE 3. Elektrogomphaeschna peterthieli, paratype SMNS BB- 2825. Drawing of forewing and hind wing fragment (scale bar represents 2 mm).

FIGURE 4. Elektrogomphaeschna peterthieli, paratype SMNS BB- 2825. A, Photograph of forewing and hind wing fragment); B, photograph of fore- and hind wing triangles (scale bars represent 2 mm).