Oligaeschna bulgariensis, Nel, Simov, Bozukov & Marinov, 2016

Nel, A, Simov, N, Bozukov, V & Marinov, M, 2016, New dragonflies and damselflies from Middle Miocene deposits in SW Bulgaria (Insecta: Odonata), Palaeontologia Electronica 25 (2), pp. 1-13 : 3-5

Oligaeschna bulgariensis sp. nov.

Figure 2

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Etymology. Named after the country of Bulgaria.

Material. Holotype Сат-1190a-b (part and counterpart, Figure 2.1-2 ), paratype Сат-55 ( Figure 2.3 ). Division of Palaeobotany and Palynology , Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria.

Diagnosis. Forewing venation only: pterostigmal brace long, oblique and sigmoidal; 19 postnodal crossveins; three rows of cells between IR2 and RP2.

Description. Holotype Сат-1190a-b ( Figure 2.1-2 ). Forewing without any trace of colouration probably hyaline, preserved part 41.4 mm long, 10.0 mm wide; distance from nodus to pterostigma 14.8 mm, pterostigma 4.5 mm long, 0.7 mm wide, covering 4 or 5 cells; pterostigmal brace elongate, distinctly oblique and sigmoidal; ca. 17 secondary antenodal crossveins distal of Ax2; 21 postnodal crossveins; hypertriangle incomplete but with crossveins; discoidal triangle elongate, transversely divided into four cells; median space free; submedian space crossed; Mspl strongly curved, five rows of cells between Mspl and MA; five Bq crossveins; oblique vein ‘O’ one cell distal of base of RP2; MA with slight curve opposite base of Rspl; beyond this level, two rows of cells between MA and RP3/4; Rspl strongly curved, with five rows of cells between it and IR2; IR2 unforked, with a posterior curve; four rows of cells between IR2 and RP 2 in broadest part; RP2 with a distinct but smooth curved row of cells before level of pterostigma.

Paratype Сат-55 ( Figure 2.3 ). Forewing without any trace of coloration, probably hyaline, preserved part 35.5 mm long, 10.5 mm wide; distance from nodus to pterostigma 16.5 mm, pterostigma 4.0 mm long, 0.6 mm wide, covering 4 or 5 cells; pterostigmal brace distinctly oblique and sigmoidal; 19 postnodal crossveins; hypertriangle incomplete but with crossveins; discoidal triangle elongate; MA with slight curve opposite base of Rspl; beyond this level two rows of cells between MA and RP3 /4; Rspl strongly curved, with five rows of cells between it and IR2; IR2 unforked, with a distinct posterior curve; three rows of cells between IR2 and RP 2 in broadest part; RP2 with a distinct but smoothly curved row of cells before level of pterostigma .

Discussion. These two forewings can be attributed to the same species because of their nearly identical wing venation and proportions. This taxon has all the autapomorphies of the family Aeshnidae as defined by Bechly (1996), i.e., “aeshnid bulla” in distal part of MA in both pairs of wings; Rspl distinctly curved with more than one row of cells between it and IR2, and area in between divided by oblique intercalary veins; probably more than two rows of cells in basal part of postdiscoidal area between level of distal angle of discoidal triangle and level of midfork; and hypertriangle traversed by at least three crossveins. Following the study of von Ellenrieder (2002), this fossil is near Oplonaeschna de Selys-Longchamps, 1883 from the shape of the veins Rspl, IR2 and RP2. The closest modern genera differ either in the narrower area between Rspl and IR2 with less than three rows of cells, or in the forked IR2 (see Martin, 1908 -1909, 1911; Fraser, 1926). This fossil differs from the recent genus Oplonaeschna in the longer pterostigma covering more than three cells. This character and the general pattern of venation fit quite well with the Cenozoic genus Oligaeschna Piton and Théobald, 1939 (revised in Nel et al., 1994). The Oligocene genus Kvacekia Prokop and Nel, 2002 is also closely related to Oligaeschna and Oplonaeschna , but it is characterized by a pterostigma covering 5 or 6 cells (4 or 5 in our fossil), and by five rows of cells in the area between IR2 and RP2 (3 in our fossil and 3 or 4 in Oligaeschna ) ( Prokop and Nel, 2002). Thus we propose to attribute our fossil to Oligaeschna . This genus comprises eight described species from Oligocene and Miocene deposits in North American and Eurasia. The incomplete state of preservation of our fossil renders difficult comparison with these fossils. It differs from O. kvaceki Prokop et al., 2007 , O. lapidaria (Cockerell and Counts, 1913 in Cockerell, 1913), and O. saurai Peñalver et al., 1996 in the pterostigmal brace being distinctly longer and more oblique ( Cockerell, 1913; Peñalver et al., 1996; Prokop et al., 2007). It shares this character with O. palaeocoerulea ( Timon-David, 1946) , O. ashutasica ( Martynov, 1929) , O. separata ( Scudder, 1890) , and O. jungi Piton and Théobald, 1939 , from which it differs in the more numerous postnodal crossveins (19 instead of 16, 14, 13, and 12, respectively) ( Scudder, 1890; Martynov, 1929; Nel et al., 1994). O. wedmanni Nel and Fleck, 2014 has five rows of cells between IR2 and RP2, unlike our fossil ( Nel and Fleck, 2014).

Figures

FIGURE 2. Oligaeschna bulgariensis sp. nov. 1, holotype Caт-1190a (part); 2, holotype Caт-1190b (part); 3, paratype Сат-55. Scale bars represent 5 mm in all figures.