The specimen described herein was collected from the Hukawng Valley of Kachin Province, Myanmar (locality in Kania et al., 2015: fig. 1). The age of Burmese amber is radiometrically dated at 98.79 ± 0.62 Ma (Earliest Cenomanian; Cohen et al., 2013) based on U–Pb zircon dating of the volcanoclastic matrix (Shi et al., 2012).

The amber containing the damselfly is yellow and transparent. Photographs were taken using a Zeiss Stereo Discovery V16 microscope system and Zen software. In most instances, incident and transmitted light were used simultaneously. All images are digitally stacked photomicrographic composites of approximately 40 individual focal planes obtained using the free software Combine ZP for a better illustration of the 3D structures. The line drawings were prepared from photographs using image-editing software (CorelDraw X7 and Adobe Photoshop CS6). The specimen is housed in the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS).

The nomenclature of the dragonfly wing venation used in this paper is based on the interpretations of Riek (1976) and Riek and Kukalová-Peck (1984), as modified by Nel et al. (1993) and Bechly (1996). The higher classification of fossil and extant Odonatoptera, as well as family and generic characters followed in the present work, are based on the phylogenetic system proposed by Bechly (1996) and Dijkstra et al. (2014) for the phylogeny of extant Zygoptera. Wing abbreviations are as follows: Cr, nodal crossvein; CuA, cubitus anterior; DC, discoidal cell; IR, intercalary radial veins; MA, median anterior; MP, median posterior; N, nodus; Pt, pterostigma; RA, radius anterior; RP, radius posterior; Sn, subnodal crossvein. All measurements are given in mm.

Order Odonata Fabricius, 1793

Suborder Zygoptera Selys-Longchamps, 1854

Family Platycnemididae Yakobson and Bianki, 1905

Subfamily Palaeodisparoneurinae Poinar, Bechly et Buckley, 2010

Genus: Palaeodisparoneura Poinar, Bechly et Buckley, 2010

Type species. Palaeodisparoneura burmanica Poinar, Bechly et Buckley, 2010

Palaeodisparoneura cretacica sp. nov. (Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 and Fig. 6)

Etymology . After the age of the species.

Material. Holotype. NIGP164075, four wings associated with a fragmentary abdomen and fragmentary legs, gender feminine; deposited in the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, China.

Type stratum and locality. Hukawng Valley, Kachin Province, Myanmar; Lowermost Cenomanian, lowermost Upper Cretaceous.

Diagnosis . Eight postnodal crossveins and eight postsubnodal crossveins present before Pt, well aligned; IR1 seven or eight cells distal of base of RP2; RP3/4 long, ending on posterior wing margin two or three cells distal of base of IR1; Pt hyaline; tarsi armed with dense spines.

Description. All wings with basal part somewhat absent. Abdomen with basal five segments preserved, 13.39 mm long; gender feminine in absence of male accessory genitalia on ventral side of segment 2. Right forewing most completed preserved (Figs. 2B, 3). Wing length 7.88 mm, maximum width 2.25 mm; length from base of RP3/4 to Pt base 5.61 mm, from Pt base to wing apex 2.03 mm. Eight postnodal crossveins and eight postsubnodal crossveins present before Pt, well aligned. Four postnodal crossveins and four postsubnodal crossveins present distal of Pt, non-aligned. Nodal structures not well preserved; Sn present and aligned with base of IR2. Midfork one long cell and 0.66 mm basal of Sn, ending on posterior margin three cells distal of base of IR1. IR2 basally straight but distally zigzagged. Base of RP2 three cells distal of Sn, lying 1.28 mm distally, nearer to N than to Pt. Base of IR1 eight cells distal of base of RP2, lying 3.81 mm distally and originating just below Pt. RP1 with a strong angle below pterostigmal brace. MA distally zigzagged and long, reaching posterior wing margin just below Pt-brace. MP curved and short. Pt one cell long, rectangular and hyaline (Fig. 5), 0.64 mm long and 0.21 mm wide, strongly braced; Pt-brace more oblique than base of Pt. All intercalary veins (except for IR1 and IR2) suppressed. Longitudinal veins RA, IR1, RP1, IR2 and RP2 strongly converging to wing apex. Other wings resemble this wing except for following differences: IR1 seven cells distal of base of RP2 in left hindwing (Fig. 2C); N well preserved (Fig. 4) in left forewing, and Sn aligned with base of IR2; MP one cell length distal of CuA, ending on posterior wing margin just below N in left hindwing (Fig. 4); CuA short and oblique in left hindwing (Fig. 4); distal part of DC and subdiscoidal cell rectangular in left hindwing (Fig. 4). Four fragmentary legs preserved (Fig. 6), paired long spines present on tibia and tarsi; tarsi armed with about 14 pairs of spines.

P. cretacica can be attributed to the subfamily Palaeodisparoneurinae Poinar, Bechly et Buckley, 2010 by sharing the characters provided by Poinar et al. (2010): small damselfly species characterized by greatly shortened veins MP (only one cell long) and CuA (only an oblique crossvein); aligned postnodal and postsubnodal crossveins; rectangular and distinctly braced Pt; RP1 strongly kinked at pterostigmal brace; very short IR1 originating beneath Pt. Palaeodisparoneura Poinar, Bechly et Buckley, 2010 is also characterized by a rectangular discoidal cell, a well-developed sub-rectangular subdiscoidal cell being not fused to the wing margin, the midfork being situated halfway between the arculus and subnodus, and the male terminalia being short. These characters are poorly discernible in P. cretacica. However, the rectangular distal parts of the discoidal cell and subdiscoidal cell further support the attribution.

Although P. cretacica shares the diagnosis of P. burmanica, some obvious differences can be observed between these two species. Specifically, P. cretacica has more postnodal crossveins and postsubnodal crossveins (eight instead of five in P. burmanica) before the pterostigma, the base of IR1 is seven or eight cells distal of the base of RP2 instead of five rows in P. burmanica, the pterostigma is hyaline instead of dark colour, a long RP3/4 ends on the posterior wing margin three cells distal of the base of IR1 instead of one cell in P. burmanica. In view of the above differences, we suggest a new species for the new specimen.

The recently described odonatans in Burmese amber help us understand the role of Burma in odonatan diversification during the mid-Cretaceous. The damselfly group is represented by some extant families, viz., Platycnemididae, Platystictidae, Hemiphlebiidae and Perilestidae (Huang et al., 2015, Poinar et al., 2010 and Zheng et al., 2016a, b, c). Besides P. burmanica, Cretadisparoneura hongi Huang, Azar, Cai et Nel, 2015 is the third representative of Platycnemididae (Huang et al., 2015). Burmalindenia imperfecta Schädel and Bechly, 2016 is the first true dragonfly from Burmese amber (Schädel and Bechly, 2016). Burmaphlebia reifi Bechly and Poinar, 2013 is the first damsel-dragonfly from amber (Bechly and Poinar, 2013). Burmahemiphlebia zhangi Zheng et al., 2016a is the first member of the Hemiphlebiidae in Burmese amber and may be the most common damselfly in these deposits, since about 40 specimens have been observed by the present authors (Zheng et al., 2016a). Palaeodysagrion cretacica Zheng et al., 2016a represents the second Cretaceous dysagrionid damselfly (Zheng et al., 2016a). Mesosticta burmatica Huang, Azar, Cai et Nel, 2015 and Mesosticta electronica Zheng et al., 2016b are the earliest fossil platystictid damselflies, which puts the origin of Platystictidae to at least mid-Cretaceous (Huang et al., 2015 and Zheng et al., 2016b). Palaeoperilestes electronicus Zheng et al., 2016c is the first fossil representative of perilestid damselfly (Zheng et al., 2016c).

Abundant extant damselfly families have been discovered from mid-Cretaceous Burmese amber, indicating the important geological position of these tropical forests for early damselfly diversification. In the present paper, a new platycnemid damselfly, P. cretacica sp. nov., representing the second species of the extinct subfamily Palaeodisparoneurinae Poinar, Bechly et Buckley, 2010, is described from Burmese amber.