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New damselfly genera in the Cretaceous Burmese amber attributable to the Platystictidae and Platycnemididae Disparoneurinae (Odonata: Zygoptera)
Cretaceous Research 56 (2015) 237e243
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Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes
New damselfly genera in the Cretaceous Burmese amber attributable to the Platystictidae and Platycnemididae Disparoneurinae (Odonata: Zygoptera) Nel c, * Diying Huang a, Dany Azar b, Chenyang Cai a, Andre a State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China b Lebanese University, Faculty of Sciences II, Department of Biology, Fanar Matn P.O. Box 26110217, Lebanon c Institut de Syst ematique, Evolution, Biodiversit e, ISYEB, UMR 7205, CNRS, MNHN, UPMC, EPHE, Mus eum national d'Histoire naturelle, Sorbonne Universit es, 57 rue Cuvier, CP 50, Entomologie, F-75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 March 2015 Accepted in revised form 7 May 2015 Available online 7 June 2015
Two new damselfly genera and species Mesosticta burmatica and Cretadisparoneura hongi, are described from the mid Cretaceous Burmese amber. They are respectively tentatively attributed to the Platystictidae and to the Platycnemididae: Disparoneurinae. These discoveries confirm that the Zygoptera of the coenagrionomorphan clade with shortened median posterior and cubitus anterior were already rather diverse during the Early Cretaceous. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Insecta Zygoptera Cretaceous Myanmar South-East Asia New genera New species
1. Introduction The strongly shortened veins MP and CuA is a spectacular specialization that occurred several times in the ‘coenagrionid’ damselflies but also in some damselfly-like Odonatoptera (Nel et al., 2012). Since recently the ‘coenagrionid’ damselflies with this structure were grouped in the Platystictidae Laidlaw, 1924 and the Protoneuridae Jacobson & Bianchi, 1905. Pessacq (2008) demonstrated the paraphyly of the latter family, so that it is currently reduced to the sole Neotropical Protoneurinae. The former Paleotropical protoneurid damselflies are now considered as subfamilies of the Platycnemididae Jacobson & Bianchi, 1905, based on the molecular phylogeny of Dijkstra et al. (2014). The fossil record of the protoneurid-like damselflies is very scarce, with only the Early Cretaceous Eoprotoneurinae Carle & Wighton, 1990 (Eoprotoneura hyperstigma Carle & Wighton, 1990), originally assigned to the Protoneuridae, but either belonging to the
Isostictidae Fraser, 1955 (Bechly, 2007), or to the stem group of the Neotropical Protoneurinae (Poinar et al., 2010); and the late Eocene genus and species Angloprotoneura emilielacroixi Nel & Fleck, 2014 (Isle of Wight, UK) (Nel & Fleck, 2014). This last taxon is known after an isolated wing that could be distinguished from all the modern genera but its exact affinities within Protoneuridae remain uncertain. Consequently the fossil record of the former ‘Paleotropical protoneurid damselflies’ is extremely reduced. In particular no fossil representative of the Platystictidae Laidlaw, 1924 or of the Disparoneurinae Fraser, 1957 is known. As the Cretaceous Burmese amber Palaeodisparoneurinae Poinar et al., 2010 are currently considered as the sister group of this clade (Poinar et al., 2010), the Disparoneurinae should be also Cretaceous. Here we describe three fossil damselflies within two new genera and species from the Burmese amber that we tentatively attributed to the Platystictidae and the Disparoneurinae.
2. Material and method * Corresponding author. E-mail addresses: [email protected] (D. Huang), [email protected] (D. Azar), [email protected] (C. Cai), [email protected] (A. Nel). http://dx.doi.org/10.1016/j.cretres.2015.05.004 0195-6671/© 2015 Elsevier Ltd. All rights reserved.
The specimens are preserved in pieces of relatively clear, yellow amber. Piece NIGP161758, containing the holotype of Mesosticta
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burmatica, is 1.0 cm long and 0.5 cm wide while amber piece NIGP161759 with paratype is 1.2 cm mm long and 0.5 cm wide. Amber piece NIGPAS161888, containing the holotype of Cretadisparoneura hongi is 2.0 cm long and 1.9 cm wide. The amber pieces were ground and polished before being examined and photographed. The piece NIGP161758 has been included in a glass coffin with Canada balsam. Fossils were examined and measured using an incident light stereomicroscope (Olympus SZX9), a stereomicroscope (Nikon SMZ 1500) and a Leitz Wetzlar binocular microscope. Photographs were taken using a Zeiss Discovery V20 microscope system and combined using Adobe Photoshop software. Optical instruments are equipped by drawing tubes and digital camera. The material is stored in the Nanjing Institute of Geology and Paleontology, Academia Sinica, China (NIGP). The fossils come from Hukawng Valley, Kachin State, Myanmar (Burma). The exact locality of the fossils cannot exactly be determined as they were acquired from fossil traders. Until recently, the precise age of the amber of Myanmar (Burmite) has been elusive. Recently an absolute age of 98.79 ± 0.62 Ma (earliest Cenomanian) was established for the majority of Burmese amber outcrops based on UePb dating of zircons inside the amber (Shi et al., 2012). The history of this amber has been reviewed by various authors (see Cruickshank and Ko, 2003). This deposit arguably contains the greatest diversity of inclusions among the Cretaceous ambers (Grimaldi et al., 2002). We follow the wing venation nomenclature of Riek & Kukalova Peck (1984), amended by Nel et al. (1993) and Bechly (1996). The higher classification of fossil and extant Odonatoptera, as well as familial and generic characters followed in the present work are based on the phylogenetic system proposed by Bechly (1996, 2014) at least for the definitions of the damselfly families. More recent works have questioned the phylogeny of the Zygoptera (Dumont et al., 2010; Davis et al., 2011; Dijkstra et al., 2014). They have been taken into account. Abbreviations for wing venation are as follow: ScP ¼ subcostal posterior; RA ¼ radius anterior; RP ¼ radius posterior; IRxx ¼ intercalary radial veins; MA ¼ media anterior; MP ¼ media posterior; CuA ¼ cubitus anterior; CuP ¼ cubitus posterior; AA ¼ analis anterior; N ¼ nodus; Sn ¼ subnodus; Pt ¼ pterostigma. 3. Systematic palaeontology Order Odonata Fabricius, 1793 Suborder Zygoptera Selys, 1854 Family Platystictidae Laidlaw, 1924 (tentative attribution) Genus Mesosticta gen. nov. Type species. Mesosticta burmatica sp. nov. Etymology. Named after the genus suffix sticta frequently used for the generic names in Platystictidae, and the Mesozoic period. Gender feminine. Diagnosis. Wing venation characters only: base of RP3/4 just basal of subnodus; base of RP2 only three cells distal of subnodus; MA long but ending one cell distal of level of base of IR1; MP three- to four-cells long; basal position of CuP; presence of a crossvein basally closing subdiscoidal cell, different from CuP; subdiscoidal cell posteriorly closed by AA and not by posterior wing margin. Mesosticta burmatica sp. nov. (Figs. 1e2) Etymology. After Burma, old name of Myanmar. Material. Holotype specimen NIGP161758 (thorax with head still attached, legs, plus two-third of left wings preserved, preserved with an Hemiptera: Fulgoromorpha). Paratype specimen NIGP161759 (thorax with head still attached, legs, plus twothird of left wings preserved).
Horizon and locality. Lowermost Cenomanian (Shi et al., 2012), Tanai Village, Hukawng Valley, northern Myanmar. Diagnosis. As for the genus (vide supra). Descriptions. Holotype specimen NIGP161758. Head apparently uniformly dark, without spots on dorsal surface, broader than long, 2.6 mm wide, with eyes well separated, distance between eyes ca. 1.4 mm; ocelli disposed on a low protuberance between the eyes; antenna three segmented; fore, mid and hind legs of the same size, femora and tibia armed with more or less paired long spines 0.4 mm long and 0.3 mm distant, length of spines decreased from base to apex of tibia, tarsi three-segmented, first tarsomere small, third one longer than first two tarsomeres together, tarsi armed with more than 10 pairs of small spines; claws forked, with distal small tooth. Wings uniformly hyaline; forewing ca. 12.0 mm long (preserved part 10.0 mm long), 1.9 mm wide, 1.0 mm wide at nodus level; distance from base to arculus 2.6 mm, from arculus to nodus 1.5 mm; petiole very long and narrow, 2.1 mm long, 0.5 mm wide; distance from base to Ax1 1.6 mm, from Ax1 to Ax2 0.9 mm, Ax2 opposite arculus, no secondary antenodal crossvein distal of Ax2; antesubnodal space free; seven preserved postnodal crossveins, the most basal ones being well aligned with postsubnodal crossveins; pterostigma not preserved; bases of RP3/4 and IR2 below subnodus, IR2 not apparently arising on RP3/4; area between RP and MA between arculus and subnodus free; base of RP2 three cells distal from subnodus; base of IR1 three cells distally; no oblique crossvein ‘O’ between IR2 and RP2; MA long ending one cell distal of base of IR1; subarculus (ventral part of arculus) ending MA just distal of RP-MA fork; discoidal cell without inner crossveins, rectangular, with MAb of inverted obliquity; subdiscoidal space without inner crossveins, elongate, with its posterior margin AA not fused with posterior margin of wing; CuP between M þ Cu and posterior wing margin in a very basal position, a supplementary crossvein between M þ CuA and AA basally closing the subdiscoidal space; CuA very short; MP three cells long, ending on posterior wing margin one cell distal of subnodus. Hind wing nearly identical to the forewing, with the following differences: wing ca. 12.0 mm long (preserved part 11.0 mm long), 2.1 mm wide, 1.1 mm wide at nodus level; distance from base to arculus 2.9 mm, from arculus to nodus 1.6 mm; petiole very long and narrow, 2.4 mm long, 0.5 mm wide; distance from base to Ax1 1.9 mm, from Ax1 to Ax2 0.9 mm; MP four-cells long; subdiscoidal space crossed; pterostigmal brace visible together with a weak kink of RP1 at its level, situated eight cells distal of subnodus. The paratype has the same venation as the holotype. Discussion. Within the Zygoptera, Mesosticta gen. nov. clusters with groups that have strongly shortened veins MP and CuA and a rectangular discoidal cell (viz. Protoneurinae, Eoprotoneurinae, Caconeurinae, Disparoneurinae, Isostictidae, Platystictidae, Palaeodisparoneurinae, and Lestoideidae). Affinities with the Neotropical Protoneuridae Jacobson and Bianchi, 1905 are excluded because Mesosticta has not the synapomorphy of this clade, viz. its subarculus (ventral part of arculus) is slightly distal to the bifurcation RP-MA (Pessacq, 2008). Also the Protoneuridae have not two crossveins between Cu þ M and posterior wing margin in petiole, unlike Mesosticta. Mesosticta differs from the Eoprotoneurinae Carle and Wighton, 1990 (Early Cretaceous Brazilian Eoprotoneura Carle and Wighton, 1990) in the longer MP (three cells long instead of one cell), Ax2 aligned with the arculus, subdiscoidal cell posteriorly separated from hind wing margin by AA, base of RP3/4 distinctly basal of
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Fig. 1. Mesosticta burmatica gen. et sp. nov. A, NIGP161758, general habitus; B, enlargement from A, showing the details of legs; C, enlargement of wing base; D, enlargement of head and leg; E, NIGP161759, general habitus; F, enlargement from E, showing the wing base. Scale bars represent 2 mm in A, C, E, and 1 mm in B, D, F.
subnodus and base of RP2 well distal of that of IR2 (see Carle & Wighton, 1990: fig. 8). Affinities with the Isostictidae are excluded because they have Ax2 basal of the arculus (Bechly, 2014), and the subdiscoidal cell completely reduced (Grand et al., 2014). The Caconeurinae (Caconeura Kirby, 1890, Esme Fraser, 1922, Melanoneura Fraser, 1922, and Phylloneura Fraser, 1922; see list of genera in Bridges, 1994) can be excluded because they have a very long IR1, a very different subdiscoidal area (rhomboid, triangular, or reduced), and Ax2 basal of the arculus (Münz, 1919; Fraser, 1933). Lestoideidae (only including the Australian endemic genus Lestoidea) can be excluded because they have a totally different branching pattern of the veins in the radial area nodus midway between the recessed midfork (with bases of RP3/4 and IR2 at the same point) and the origin of RP2, and there are three long
intercalary veins between RP1 and RP2, as well as a completely reduced subdiscoidal cell (Münz, 1919: fig. 45). The Burmese amber Palaeodisparoneurinae have a shorter hind wing discoidal cell, an open forewing one, base of RP3/4 near midway between arculus and nodus, a very short IR1, and a much reduced MP (Poinar et al., 2010). The Disparoneurinae (‘Palaeotropical Protoneuridae’ sensu Pessacq, 2008), although considered as problematic by Watson (1992), are supported in the phylogenetic analysis of Pessacq (2008) by genital characters plus the head dorsal color uniformly back. Unfortunately these are not available in our fossils. Several Disparoneurinae have a CuP-crossing recessed in a very basal position as in Mesosticta (Münz, 1919), but none of them have two small veins (basal CuP and distal crossvein) in area between anal vein and MP þ Cu, as in Mesosticta.
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Fig. 2. Mesosticta burmatica gen. et sp. nov. NIGP161758, drawing of wings. A, forewing; B, hind wing. Arrows indicate most basal crossvein between MP þ Cu and anal vein. Scale bar represents 2 mm.
Bridges (1994) listed the following genera in Disparoneurinae: Chlorocnemis Selys, 1863, Disparoneura Selys, 1860, Elattoneura Cowley, 1935, Nososticta Selys, 1860, Prodasineura Cowley, 1934, Isomecocnemis Cowley, 1936. The genus Arabineura Schneider & Dumont, 1995 can be added to this list (Schneider & Dumont, 1995). Mesosticta differs from Chlorocnemis in the base of RP3/4 just basal of subnodus instead of being distal; basal position of CuP; presence of crossvein basally closing the subdiscoidal cell, different from CuP (Münz, 1919). Mesosticta differs from Prodasineura in the presence of the subdiscoidal cell posteriorly closed (Cowley, 1936). Mesosticta differs from Nososticta in the longer MP and subdiscoidal cell posteriorly closed. Mesosticta shares with Isomecocnemis, Disparoneura, Arabineura, and Elattoneura a similar shape of the subdiscoidal cell. Mesosticta differs from Isomecocnemis in the shorter MP and shorter IR1 (Cowley, 1936). Mesosticta differs from Disparoneura in the base of RP2 closer to subnodus, and basal position of CuP. Mesosticta differs from Arabineura in the base of RP2 only three cells distal of subnodus instead of five cells. Elattoneura has its MP extending farther than in Mesosticta and in Disparoneura, a very long MA, and base of RP2 very far from subnodus (Fraser, 1933; Cowley, 1936). The Platystictidae (Drepanosticta Laidlaw, 1917, Platysticta Selys. 1860, Ceylonosticta Fraser, 1931, Telosticta Dow and Orr, 2012, Protosticta Selys, 1885, Sinosticta Wilson, 1997, Sulcosticta van Tol, 2005, Palaemnema Selys, 1860, see Wilson, 1997; Van Tol, 2005, 2009; Dow and Orr, 2012; Dijkstra et al., 2014) share with Mesosticta the CuP-crossing recessed in a very basal position, a character considered as apomorphic by Bechly (1996, 2014) and by Van Tol (2009), but also present in the Isostictidae and some Disparoneurinae (Nososticta). Nevertheless, only the Platystictidae have at least two small veins (basal CuP and a distal crossvein) in the area between anal vein and MP þ Cu, as in Mesosticta. This character constitutes a potential synapomorphy of Mesosticta with the Platystictidae. An attribution of our fossil to any of the modern platystictid genera can be excluded because all of them have a very long IR1 (but see remark below), a very different subdiscoidal area (rhomboid, triangular, or reduced), and Ax2 basal of the arculus (Laidlaw, 1917; Münz, 1919; Fraser, 1933; Van Tol, 2005). To conclude, the wing venation of Mesosticta shows strong similarities with those of some modern Disparoneurinae (e.g.
Disparoneura) but it shares with the Platystictidae one putative apomorphy in the presence of two small veins in the space between MP þ Cu and posterior wing margin in the petiole. Thus its exact relationships cannot be accurately determined. We provisionally put it in the Platystictidae. Remark. Only the damselfly attributed to the platystictid Drepanosticta polychromatica Fraser, 1932 by Zia (2010: fig. 4.43b) has a short IR1 as in Mesosticta, and a subdiscoidal cell similar to that of Mesosticta, but an MP longer than in Mesosticta. This damselfly does not correspond well to D. polychromatica because in the original description of this species, Fraser (1932: 338) indicated that this species has 15 postnodal crossveins in forewing while the damselfly figured by Zia has only 10; also RP3/4 is arising below the subnodus which is not the case of the specimen of Zia; lastly AA is emerging distal of CuP, while it is emerging basal of CuP in the specimen of Zia. The damselfly figured by Zia should be revised. Family Platycnemididae Jacobson & Bianchi, 1905 Subfamily Disparoneurinae Fraser, 1957 (tentative attribution) Genus Cretadisparoneura gen. nov. Type species. Cretadisparoneura hongi sp. nov. Etymology. Named after the Cretaceous period and the genus Disparoneura. Gender feminine. Diagnosis. Wing venation characters only. Wings not falcate; absence of intercalary veins (except IR1 and IR2); pterostigma covering one cell; kink of RP1 at pterostigmal brace; distal side of pterostigma not very oblique; IR1 not very long; base of RP3/4 aligned with subnodus; base of IR2 well distal of subnodus; Ax2 distal of arculus; strongly shortened veins MP and CuA; rectangular discoidal cell; subdiscoidal cell posteriorly closed by AA; only one crossvein (CuP) between MP þ Cu and posterior wing margin in petiole. Cretadisparoneura hongi sp. nov. (Figs. 3e4) Etymology. After our friend and colleague Pr. You-Chong Hong, specialist on fossil insects. Material. Holotype specimen NIGPAS161888 (female, nearly complete body thorax with head and complete abdomen still attached, legs, plus remnants of the four wings preserved).
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Fig. 3. Cretadisparoneura hongi gen. et sp. nov. NIGPAS161888, A, general habitus; B, detail of bases of wings; C, wings; D, apex of abdomen. Scale bars represent 5 mm in a, 2 mm in B, C, 1 mm in D.
Horizon and locality. Lowermost Cenomanian (Shi et al., 2012), Tanai Village, Hukawng Valley, northern Myanmar. Diagnosis. As for the genus (vide supra). Description. Body coloration not preserved, 14.5 mm long. Head 0.87 mm long, 1.73 mm wide, eyes well separated; thorax 2.17 mm long; abdomen 11.2 mm long, 0.61 mm wide; with ovipositor clearly visible but short, not reaching the level of apex of abdomen. Wings uniformly hyaline; forewing ca. 8.1 mm long, 1.7 mm wide, 0.8 mm wide at nodus level; distance from base to arculus 1.9 mm, from arculus to nodus 1.2 mm; petiole very long and narrow, 1.6 mm long, 0.3 mm wide; distance from
base to Ax1 1.2 mm, from Ax1 to Ax2 0.8 mm, Ax2 just distal to arculus, no secondary antenodal crossvein distal of Ax2; antesubnodal space free; five preserved postnodal crossveins, well aligned with postsubnodal crossveins; pterostigma well preserved covering one cell, 0.4 mm long, 0.2 mm wide; base of RP3/4 below subnodus, base of IR2 one cell, 0.8 mm distally, that of RP2 two cells distal of that of IR2; base of IR1 three cells distally; area between RP and MA between arculus and subnodus free; no oblique crossvein; discoidal cell free, rectangular, with MAb of inverted obliquity; subdiscoidal space free, elongate, with posterior margin not fused with posterior margin of
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Fig. 4. Cretadisparoneura hongi gen. et sp. nov. NIGPAS161888, A, forewing; B, distal part of hind wing. Scale bar represents 2 mm.
wing; MA long ending below pterostigma; CuA very short; MP one cell long. Hind wing nearly identical to the forewing, except for the base of IR1 two cells distal of that of RP2, and MA ending on posterior wing margin below pterostigma instead of one cell distally. Discussion. Cretadisparoneura gen. nov. differs from the Burmese amber Mesosticta in the very short MP and the presence of only CuP in area between MP þ Cu and posterior wing margin in the petiole. An attribution of Cretadisparoneura to the coenagrionomorphan clade is supported by the following characters: absence of intercalary veins (except IR1 and IR2), and kink of RP1 at pterostigmal brace. Cretadisparoneura clusters with groups that have strongly shortened veins MP and CuA and a rectangular discoidal cell (viz. Palaeodisparoneurinae, Protoneurinae, Eoprotoneurinae, Caconeurinae, Disparoneurinae, Isostictidae, Platystictidae, and Lestoideidae). Isostictidae can be excluded because they have Ax2 basal of the arculus, the distal side of the pterostigma very oblique, and the subdiscoidal cell completely reduced. Platystictidae can be excluded because they have two crossveins in the petiole between
MP þ Cu and posterior wing margin, much longer wings with a falcate apex, a very long IR1, and unbraced pterostigmata (except in Neotropical Palaemnematinae) of very different shape, as well as a very different subdiscoidal area (rhomboid, triangular, or reduced). Only Drepanosticta polychromatica shows strong similarities with Cretadisparoneura, except in the base of IR2 close to subnodus instead of being two cells distally. The Lestoideidae can be excluded because they have much different pterostigmata (2.5 cells long, unbraced, and with oblique basal side) and a totally different branching pattern of the veins in the radial area (the nodus is midway between the recessed midfork and the origin of RP2, and there are three long intercalary veins between RP1 and RP2), as well as a completely reduced subdiscoidal cell. The Cretaceous Eoprotoneurinae share with Cretadisparoneura the base of RP3/4 aligned with subnodus, but they differ from it in the reduced subdiscoidal cell, and longer pterostigma. Within the Neotropical Protoneuridae, some genera have a greatly shortened MP, but this vein still extends at least over 2e3 cells. Some Protoneuridae, like Junix, also have a distinctly kinked RP1 at the pterostigmal brace and the origin of RP3/4 very close to subnodus, but differ in some other characters (e.g. origin of IR2 below subnodus).
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The Caconeurinae can be excluded because they have a venation that is very similar to Platystictidae, with very long IR1, and long MP. Cretadisparoneura differs from the Burmese amber Palaeodisparoneurinae (Hemidisparoneura and Palaeodisparoneura) in the base of RP3/4 below subnodus instead of being distinctly basal and base of IR2 well distal of subnodus. The modern Disparoneurinae show the closest similarities with Cretadisparoneura. Thus we provisionally include it in this subfamily. It differs from the modern genera Isomecocnemis, Disparoneura, Arabineura, and Elattoneura in the very short MP. Cretadisparoneura shares with Chlorocnemis the base of RP3/4 aligned with subnodus and very short MP, but it differs from this genus in the base of IR2 well distal from subnodus, and the distinctly shorter IR1 (Münz, 1919). Cretadisparoneura differs from Nososticta and Prodasineura in the presence of the subdiscoidal cell posteriorly closed (Cowley, 1936). 4. Conclusion The present discoveries of putative Platystictidae and Disparoneurinae in layers dated around 100 Ma is congruent with the hypothesis of Davis et al. (2011) who proposed estimated ages for the first appearance (MRP) of 125 Ma for the Platystictidae and of 112 Ma for the Platycnemididae, on the basis of a molecular phylogenetic analysis supported by an extensive use of the Odonata fossil record. Together with the presence of the Palaeodisparoneurinae in the same amber, these fossils suggest rapid diversifications of these families around 110e100 Ma. Acknowledgments HDY would like to thank National Basic Research Program of China (2012CB821903), Outstanding Youth Foundation of Jiangsu Province (BK 2012049), and the National Natural Science Foundation of China (91114201) for fund supporting. This paper is a contribution to the team project “Biodiversity: Origin, Structure, Evolution and Geology” granted to DA by the Lebanese University. We sincerely thank two anonymous referees for their useful remarks on the first version of the paper. References €der der rezenten Bechly, G., 1996. Morphologische Untersuchungen am Flügelgea Libellen und deren Stammgruppenvertreter (Insecta; Pterygota; Odonata), unter besonderer Berücksichtigung der Phylogenetischen Systematik und des € blingen Special Volume 2, 402. Grundplanes der Odonata. Petalura, Bo Bechly, G., 2007. Chapter 11.5 Odonata: damselflies and dragonflies. pp. 184e222. In: Martill, D., Bechly, G., Loveridge, R. (Eds.), The Crato fossil beds of Brazil: Window into an ancient world. Cambridge University Press, Cambridge, p. 624. Bechly, G., 2014. Phylogenetic systematics of Odonata. - homepage on the Internet. http://www.bernstein.naturkundemuseumbw.de/odonata/phylosys.htm. Bridges, C.A., 1994. Catalogue of the family-group, genus-group and species-group names of the Odonata of the World, Third edition. Bridges C.A. (publisher), Urbana, Illinois, USA, p. 950. Carle, F.L., Wighton, D.C., 1990. Chapter 3. Odonata. pp. 51e68. In: Grimaldi, D.A. (Ed.), Insects from the Santana Formation, Lower Cretaceous, of Brazil, Bulletin of the American Museum of Natural History, 195, pp. 1e191.
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Cowley, J., 1936. The Disparoneura complex: generic characters and lists of species (Odonata). Annals & Magazine of Natural History 10 (17), 509e526. Cruickshank, R.D., Ko, K., 2003. Geology of an amber locality in the Hukawng Valley, Northern Myanmar. Journal of Asian Earth Sciences 21, 441e455. Davis, R.B., Nicholson, D.B., Saunders, E.L.R., Mayhew, P.J., 2011. Fossil gaps inferred from phylogenies alter the apparent nature of diversification in dragonflies and their relatives. BMC Evolutionary Biology 11, 10. Dijkstra, K.-D.B., Kalkman, V.J., Dow, R.A., Stokvis, F.R., Van Tol, J., 2014. Redefining the damselfly families: a comprehensive molecular phylogeny of Zygoptera (Odonata). Systematic Entomology 39, 68e96. Dow, R.A., Orr, A.G., 2012. Telosticta, a new damselfly genus from Borneo and Palawan (Odonata: Zygoptera: Platystictidae). Raffles Bulletin of Zoology 60, 361e397. Dumont, H.J., Vierstraete, A., Vanfleteren, J.R., 2010. A molecular phylogeny of the Odonata (Insecta). Systematic Entomology 35, 6e18. Fraser, F.C., 1932. Indian dragonflies. Part XXXVIII. Journal of the Bombay Natural History Society 35, 325e341. Fraser, F.C., 1933. Odonata. In: Stephenson, J. (Ed.), The fauna of British India, including Ceylon and Burma, 1. Taylor and Francis (publs), London iexiii þ 1e423. Grand, D., Marinov, M., Cook, C., Jourdan, H., Rouys, S., Theurkauff, J., 2014. Identification key to adults Odonata of New Caledonia and Wallis and Futuna. Odonatologica 43, 247e277. Grimaldi, D.A., Engel, M.S., Nascimbene, P.C., 2002. Fossiliferous Cretaceous amber from Myanmar (Burma): its rediscovery, biotic diversity, and paleontological significance. American Museum Novitates 3361, 1e72. Laidlaw, F.F., 1917. A list of the dragonflies recorded from the Indian Empire with special reference to the collection of the Indian Museum. Part 2. The family Agrioninae. A. The sections Podolestes, Platycnemis, Platysticta and Protoneura. Records of the Indian Museum 13, 321e348. Münz, P.A., 1919. A venational study of the suborder Zygoptera (Odonata) with keys for the identification of genera. Memoirs of the Entomological Society (of the Academy of Natural Sciences) 3, 1e78. thoux, O., Fleck, G., 2012. Systematics and evolution Nel, A., Bechly, G., Prokop, J., Be of Paleozoic and Mesozoic damselfly-like Odonatoptera of the ‘Protozygopteran’ grade. Journal of Paleontology 86, 81e104. Nel, A., Fleck, G., 2014. Dragonflies and damselflies (Insecta: Odonata) from the Late Eocene of the Isle of Wight. Earth and Environmental Science. Transactions of the Royal Society of Edinburgh 104, 283e306. Nel, A., Martinez-Delclos, X., Paicheler, J.-C., Henrotay, M., 1993. Les ‘Anisozygoptera’ nie et classification (Odonata). Martinia Nume ro Hors Se rie 3, fossiles. Phyloge 1e311. Pessacq, P., 2008. Phylogeny of Neotropical Protoneuridae (Odonata: Zygoptera) and a preliminary study of their relationship with related families. Systematic Entomology 33, 511e528. Poinar Jr., G.O., Bechly, G., Buckley, R., 2010. First record of Odonata and a new subfamily of damselflies from Early Cretaceous Burmese amber. Palaeodiversity 3, 15e22. -Peck, J., 1984. A new interpretation of dragonfly wing venation Riek, E.F., Kukalova based upon Early Carboniferous fossils from Argentina (Insecta: Odonatoidea) and basic characters states in pterygote wings. Canadian Journal of Zoology 62, 1150e1166. Schneider, W., Dumont, H.J., 1995. Arabineura n. gen., a new protoneurid genus from Arabia, with the description of the hitherto unknown female of Arabineura khalidi (Schneider, 1988) comb. nov. (Insecta: Odonata: Protoneuridae). Biologisch Jaarboek, Dodonaea 62, 114e120. Shi, G., Grimaldi, D.A., Harlow, G.E., Wang, J., Wang, J., Wang, M., Lei, W., Li, Q., Li, X., 2012. Age constraint on Burmese amber based on U-Pb dating of zircons. Cretaceous Research 37, 155e163. Van Tol, J., 2005. Revision of the Platystictidae of the Philippines (Odonata), excluding the Drepanosticta halterata group, with descriptions of twenty-one new species. Zoologische Mededelingen 79, 195e282. Van Tol, J., 2009. Phylogeny and biogeography of the Platystictidae (Odonata). PhD thesis. Institute Biology, Faculty of Science, Leiden University, pp. 1e304. Watson, J.A.L., 1992. The subfamilies of Protoneuridae (Zygoptera). Odonatologica 21, 195e201. Wilson, K.D.P., 1997. The Platystictidae of Hong Kong and Guang Dong, with description of a new genus and two new species. Odonatologica 26, 53e63. Zia, A., 2010. Biosystematics of damselflies (Zygoptera: Odonata) of Pakistan. PhD Thesis. Department of Entomology, Faculty of Crop and Food Sciences, Pir Mehr Ali Shah, Arid Agriculture University, Rawalpindi e Pakistan, p. 285.
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Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes
New damselfly genera in the Cretaceous Burmese amber attributable to the Platystictidae and Platycnemididae Disparoneurinae (Odonata: Zygoptera) Nel c, * Diying Huang a, Dany Azar b, Chenyang Cai a, Andre a State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China b Lebanese University, Faculty of Sciences II, Department of Biology, Fanar Matn P.O. Box 26110217, Lebanon c Institut de Syst ematique, Evolution, Biodiversit e, ISYEB, UMR 7205, CNRS, MNHN, UPMC, EPHE, Mus eum national d'Histoire naturelle, Sorbonne Universit es, 57 rue Cuvier, CP 50, Entomologie, F-75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 March 2015 Accepted in revised form 7 May 2015 Available online 7 June 2015
Two new damselfly genera and species Mesosticta burmatica and Cretadisparoneura hongi, are described from the mid Cretaceous Burmese amber. They are respectively tentatively attributed to the Platystictidae and to the Platycnemididae: Disparoneurinae. These discoveries confirm that the Zygoptera of the coenagrionomorphan clade with shortened median posterior and cubitus anterior were already rather diverse during the Early Cretaceous. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Insecta Zygoptera Cretaceous Myanmar South-East Asia New genera New species
1. Introduction The strongly shortened veins MP and CuA is a spectacular specialization that occurred several times in the ‘coenagrionid’ damselflies but also in some damselfly-like Odonatoptera (Nel et al., 2012). Since recently the ‘coenagrionid’ damselflies with this structure were grouped in the Platystictidae Laidlaw, 1924 and the Protoneuridae Jacobson & Bianchi, 1905. Pessacq (2008) demonstrated the paraphyly of the latter family, so that it is currently reduced to the sole Neotropical Protoneurinae. The former Paleotropical protoneurid damselflies are now considered as subfamilies of the Platycnemididae Jacobson & Bianchi, 1905, based on the molecular phylogeny of Dijkstra et al. (2014). The fossil record of the protoneurid-like damselflies is very scarce, with only the Early Cretaceous Eoprotoneurinae Carle & Wighton, 1990 (Eoprotoneura hyperstigma Carle & Wighton, 1990), originally assigned to the Protoneuridae, but either belonging to the
Isostictidae Fraser, 1955 (Bechly, 2007), or to the stem group of the Neotropical Protoneurinae (Poinar et al., 2010); and the late Eocene genus and species Angloprotoneura emilielacroixi Nel & Fleck, 2014 (Isle of Wight, UK) (Nel & Fleck, 2014). This last taxon is known after an isolated wing that could be distinguished from all the modern genera but its exact affinities within Protoneuridae remain uncertain. Consequently the fossil record of the former ‘Paleotropical protoneurid damselflies’ is extremely reduced. In particular no fossil representative of the Platystictidae Laidlaw, 1924 or of the Disparoneurinae Fraser, 1957 is known. As the Cretaceous Burmese amber Palaeodisparoneurinae Poinar et al., 2010 are currently considered as the sister group of this clade (Poinar et al., 2010), the Disparoneurinae should be also Cretaceous. Here we describe three fossil damselflies within two new genera and species from the Burmese amber that we tentatively attributed to the Platystictidae and the Disparoneurinae.
2. Material and method * Corresponding author. E-mail addresses: [email protected] (D. Huang), [email protected] (D. Azar), [email protected] (C. Cai), [email protected] (A. Nel). http://dx.doi.org/10.1016/j.cretres.2015.05.004 0195-6671/© 2015 Elsevier Ltd. All rights reserved.
The specimens are preserved in pieces of relatively clear, yellow amber. Piece NIGP161758, containing the holotype of Mesosticta
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burmatica, is 1.0 cm long and 0.5 cm wide while amber piece NIGP161759 with paratype is 1.2 cm mm long and 0.5 cm wide. Amber piece NIGPAS161888, containing the holotype of Cretadisparoneura hongi is 2.0 cm long and 1.9 cm wide. The amber pieces were ground and polished before being examined and photographed. The piece NIGP161758 has been included in a glass coffin with Canada balsam. Fossils were examined and measured using an incident light stereomicroscope (Olympus SZX9), a stereomicroscope (Nikon SMZ 1500) and a Leitz Wetzlar binocular microscope. Photographs were taken using a Zeiss Discovery V20 microscope system and combined using Adobe Photoshop software. Optical instruments are equipped by drawing tubes and digital camera. The material is stored in the Nanjing Institute of Geology and Paleontology, Academia Sinica, China (NIGP). The fossils come from Hukawng Valley, Kachin State, Myanmar (Burma). The exact locality of the fossils cannot exactly be determined as they were acquired from fossil traders. Until recently, the precise age of the amber of Myanmar (Burmite) has been elusive. Recently an absolute age of 98.79 ± 0.62 Ma (earliest Cenomanian) was established for the majority of Burmese amber outcrops based on UePb dating of zircons inside the amber (Shi et al., 2012). The history of this amber has been reviewed by various authors (see Cruickshank and Ko, 2003). This deposit arguably contains the greatest diversity of inclusions among the Cretaceous ambers (Grimaldi et al., 2002). We follow the wing venation nomenclature of Riek & Kukalova Peck (1984), amended by Nel et al. (1993) and Bechly (1996). The higher classification of fossil and extant Odonatoptera, as well as familial and generic characters followed in the present work are based on the phylogenetic system proposed by Bechly (1996, 2014) at least for the definitions of the damselfly families. More recent works have questioned the phylogeny of the Zygoptera (Dumont et al., 2010; Davis et al., 2011; Dijkstra et al., 2014). They have been taken into account. Abbreviations for wing venation are as follow: ScP ¼ subcostal posterior; RA ¼ radius anterior; RP ¼ radius posterior; IRxx ¼ intercalary radial veins; MA ¼ media anterior; MP ¼ media posterior; CuA ¼ cubitus anterior; CuP ¼ cubitus posterior; AA ¼ analis anterior; N ¼ nodus; Sn ¼ subnodus; Pt ¼ pterostigma. 3. Systematic palaeontology Order Odonata Fabricius, 1793 Suborder Zygoptera Selys, 1854 Family Platystictidae Laidlaw, 1924 (tentative attribution) Genus Mesosticta gen. nov. Type species. Mesosticta burmatica sp. nov. Etymology. Named after the genus suffix sticta frequently used for the generic names in Platystictidae, and the Mesozoic period. Gender feminine. Diagnosis. Wing venation characters only: base of RP3/4 just basal of subnodus; base of RP2 only three cells distal of subnodus; MA long but ending one cell distal of level of base of IR1; MP three- to four-cells long; basal position of CuP; presence of a crossvein basally closing subdiscoidal cell, different from CuP; subdiscoidal cell posteriorly closed by AA and not by posterior wing margin. Mesosticta burmatica sp. nov. (Figs. 1e2) Etymology. After Burma, old name of Myanmar. Material. Holotype specimen NIGP161758 (thorax with head still attached, legs, plus two-third of left wings preserved, preserved with an Hemiptera: Fulgoromorpha). Paratype specimen NIGP161759 (thorax with head still attached, legs, plus twothird of left wings preserved).
Horizon and locality. Lowermost Cenomanian (Shi et al., 2012), Tanai Village, Hukawng Valley, northern Myanmar. Diagnosis. As for the genus (vide supra). Descriptions. Holotype specimen NIGP161758. Head apparently uniformly dark, without spots on dorsal surface, broader than long, 2.6 mm wide, with eyes well separated, distance between eyes ca. 1.4 mm; ocelli disposed on a low protuberance between the eyes; antenna three segmented; fore, mid and hind legs of the same size, femora and tibia armed with more or less paired long spines 0.4 mm long and 0.3 mm distant, length of spines decreased from base to apex of tibia, tarsi three-segmented, first tarsomere small, third one longer than first two tarsomeres together, tarsi armed with more than 10 pairs of small spines; claws forked, with distal small tooth. Wings uniformly hyaline; forewing ca. 12.0 mm long (preserved part 10.0 mm long), 1.9 mm wide, 1.0 mm wide at nodus level; distance from base to arculus 2.6 mm, from arculus to nodus 1.5 mm; petiole very long and narrow, 2.1 mm long, 0.5 mm wide; distance from base to Ax1 1.6 mm, from Ax1 to Ax2 0.9 mm, Ax2 opposite arculus, no secondary antenodal crossvein distal of Ax2; antesubnodal space free; seven preserved postnodal crossveins, the most basal ones being well aligned with postsubnodal crossveins; pterostigma not preserved; bases of RP3/4 and IR2 below subnodus, IR2 not apparently arising on RP3/4; area between RP and MA between arculus and subnodus free; base of RP2 three cells distal from subnodus; base of IR1 three cells distally; no oblique crossvein ‘O’ between IR2 and RP2; MA long ending one cell distal of base of IR1; subarculus (ventral part of arculus) ending MA just distal of RP-MA fork; discoidal cell without inner crossveins, rectangular, with MAb of inverted obliquity; subdiscoidal space without inner crossveins, elongate, with its posterior margin AA not fused with posterior margin of wing; CuP between M þ Cu and posterior wing margin in a very basal position, a supplementary crossvein between M þ CuA and AA basally closing the subdiscoidal space; CuA very short; MP three cells long, ending on posterior wing margin one cell distal of subnodus. Hind wing nearly identical to the forewing, with the following differences: wing ca. 12.0 mm long (preserved part 11.0 mm long), 2.1 mm wide, 1.1 mm wide at nodus level; distance from base to arculus 2.9 mm, from arculus to nodus 1.6 mm; petiole very long and narrow, 2.4 mm long, 0.5 mm wide; distance from base to Ax1 1.9 mm, from Ax1 to Ax2 0.9 mm; MP four-cells long; subdiscoidal space crossed; pterostigmal brace visible together with a weak kink of RP1 at its level, situated eight cells distal of subnodus. The paratype has the same venation as the holotype. Discussion. Within the Zygoptera, Mesosticta gen. nov. clusters with groups that have strongly shortened veins MP and CuA and a rectangular discoidal cell (viz. Protoneurinae, Eoprotoneurinae, Caconeurinae, Disparoneurinae, Isostictidae, Platystictidae, Palaeodisparoneurinae, and Lestoideidae). Affinities with the Neotropical Protoneuridae Jacobson and Bianchi, 1905 are excluded because Mesosticta has not the synapomorphy of this clade, viz. its subarculus (ventral part of arculus) is slightly distal to the bifurcation RP-MA (Pessacq, 2008). Also the Protoneuridae have not two crossveins between Cu þ M and posterior wing margin in petiole, unlike Mesosticta. Mesosticta differs from the Eoprotoneurinae Carle and Wighton, 1990 (Early Cretaceous Brazilian Eoprotoneura Carle and Wighton, 1990) in the longer MP (three cells long instead of one cell), Ax2 aligned with the arculus, subdiscoidal cell posteriorly separated from hind wing margin by AA, base of RP3/4 distinctly basal of
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Fig. 1. Mesosticta burmatica gen. et sp. nov. A, NIGP161758, general habitus; B, enlargement from A, showing the details of legs; C, enlargement of wing base; D, enlargement of head and leg; E, NIGP161759, general habitus; F, enlargement from E, showing the wing base. Scale bars represent 2 mm in A, C, E, and 1 mm in B, D, F.
subnodus and base of RP2 well distal of that of IR2 (see Carle & Wighton, 1990: fig. 8). Affinities with the Isostictidae are excluded because they have Ax2 basal of the arculus (Bechly, 2014), and the subdiscoidal cell completely reduced (Grand et al., 2014). The Caconeurinae (Caconeura Kirby, 1890, Esme Fraser, 1922, Melanoneura Fraser, 1922, and Phylloneura Fraser, 1922; see list of genera in Bridges, 1994) can be excluded because they have a very long IR1, a very different subdiscoidal area (rhomboid, triangular, or reduced), and Ax2 basal of the arculus (Münz, 1919; Fraser, 1933). Lestoideidae (only including the Australian endemic genus Lestoidea) can be excluded because they have a totally different branching pattern of the veins in the radial area nodus midway between the recessed midfork (with bases of RP3/4 and IR2 at the same point) and the origin of RP2, and there are three long
intercalary veins between RP1 and RP2, as well as a completely reduced subdiscoidal cell (Münz, 1919: fig. 45). The Burmese amber Palaeodisparoneurinae have a shorter hind wing discoidal cell, an open forewing one, base of RP3/4 near midway between arculus and nodus, a very short IR1, and a much reduced MP (Poinar et al., 2010). The Disparoneurinae (‘Palaeotropical Protoneuridae’ sensu Pessacq, 2008), although considered as problematic by Watson (1992), are supported in the phylogenetic analysis of Pessacq (2008) by genital characters plus the head dorsal color uniformly back. Unfortunately these are not available in our fossils. Several Disparoneurinae have a CuP-crossing recessed in a very basal position as in Mesosticta (Münz, 1919), but none of them have two small veins (basal CuP and distal crossvein) in area between anal vein and MP þ Cu, as in Mesosticta.
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Fig. 2. Mesosticta burmatica gen. et sp. nov. NIGP161758, drawing of wings. A, forewing; B, hind wing. Arrows indicate most basal crossvein between MP þ Cu and anal vein. Scale bar represents 2 mm.
Bridges (1994) listed the following genera in Disparoneurinae: Chlorocnemis Selys, 1863, Disparoneura Selys, 1860, Elattoneura Cowley, 1935, Nososticta Selys, 1860, Prodasineura Cowley, 1934, Isomecocnemis Cowley, 1936. The genus Arabineura Schneider & Dumont, 1995 can be added to this list (Schneider & Dumont, 1995). Mesosticta differs from Chlorocnemis in the base of RP3/4 just basal of subnodus instead of being distal; basal position of CuP; presence of crossvein basally closing the subdiscoidal cell, different from CuP (Münz, 1919). Mesosticta differs from Prodasineura in the presence of the subdiscoidal cell posteriorly closed (Cowley, 1936). Mesosticta differs from Nososticta in the longer MP and subdiscoidal cell posteriorly closed. Mesosticta shares with Isomecocnemis, Disparoneura, Arabineura, and Elattoneura a similar shape of the subdiscoidal cell. Mesosticta differs from Isomecocnemis in the shorter MP and shorter IR1 (Cowley, 1936). Mesosticta differs from Disparoneura in the base of RP2 closer to subnodus, and basal position of CuP. Mesosticta differs from Arabineura in the base of RP2 only three cells distal of subnodus instead of five cells. Elattoneura has its MP extending farther than in Mesosticta and in Disparoneura, a very long MA, and base of RP2 very far from subnodus (Fraser, 1933; Cowley, 1936). The Platystictidae (Drepanosticta Laidlaw, 1917, Platysticta Selys. 1860, Ceylonosticta Fraser, 1931, Telosticta Dow and Orr, 2012, Protosticta Selys, 1885, Sinosticta Wilson, 1997, Sulcosticta van Tol, 2005, Palaemnema Selys, 1860, see Wilson, 1997; Van Tol, 2005, 2009; Dow and Orr, 2012; Dijkstra et al., 2014) share with Mesosticta the CuP-crossing recessed in a very basal position, a character considered as apomorphic by Bechly (1996, 2014) and by Van Tol (2009), but also present in the Isostictidae and some Disparoneurinae (Nososticta). Nevertheless, only the Platystictidae have at least two small veins (basal CuP and a distal crossvein) in the area between anal vein and MP þ Cu, as in Mesosticta. This character constitutes a potential synapomorphy of Mesosticta with the Platystictidae. An attribution of our fossil to any of the modern platystictid genera can be excluded because all of them have a very long IR1 (but see remark below), a very different subdiscoidal area (rhomboid, triangular, or reduced), and Ax2 basal of the arculus (Laidlaw, 1917; Münz, 1919; Fraser, 1933; Van Tol, 2005). To conclude, the wing venation of Mesosticta shows strong similarities with those of some modern Disparoneurinae (e.g.
Disparoneura) but it shares with the Platystictidae one putative apomorphy in the presence of two small veins in the space between MP þ Cu and posterior wing margin in the petiole. Thus its exact relationships cannot be accurately determined. We provisionally put it in the Platystictidae. Remark. Only the damselfly attributed to the platystictid Drepanosticta polychromatica Fraser, 1932 by Zia (2010: fig. 4.43b) has a short IR1 as in Mesosticta, and a subdiscoidal cell similar to that of Mesosticta, but an MP longer than in Mesosticta. This damselfly does not correspond well to D. polychromatica because in the original description of this species, Fraser (1932: 338) indicated that this species has 15 postnodal crossveins in forewing while the damselfly figured by Zia has only 10; also RP3/4 is arising below the subnodus which is not the case of the specimen of Zia; lastly AA is emerging distal of CuP, while it is emerging basal of CuP in the specimen of Zia. The damselfly figured by Zia should be revised. Family Platycnemididae Jacobson & Bianchi, 1905 Subfamily Disparoneurinae Fraser, 1957 (tentative attribution) Genus Cretadisparoneura gen. nov. Type species. Cretadisparoneura hongi sp. nov. Etymology. Named after the Cretaceous period and the genus Disparoneura. Gender feminine. Diagnosis. Wing venation characters only. Wings not falcate; absence of intercalary veins (except IR1 and IR2); pterostigma covering one cell; kink of RP1 at pterostigmal brace; distal side of pterostigma not very oblique; IR1 not very long; base of RP3/4 aligned with subnodus; base of IR2 well distal of subnodus; Ax2 distal of arculus; strongly shortened veins MP and CuA; rectangular discoidal cell; subdiscoidal cell posteriorly closed by AA; only one crossvein (CuP) between MP þ Cu and posterior wing margin in petiole. Cretadisparoneura hongi sp. nov. (Figs. 3e4) Etymology. After our friend and colleague Pr. You-Chong Hong, specialist on fossil insects. Material. Holotype specimen NIGPAS161888 (female, nearly complete body thorax with head and complete abdomen still attached, legs, plus remnants of the four wings preserved).
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Fig. 3. Cretadisparoneura hongi gen. et sp. nov. NIGPAS161888, A, general habitus; B, detail of bases of wings; C, wings; D, apex of abdomen. Scale bars represent 5 mm in a, 2 mm in B, C, 1 mm in D.
Horizon and locality. Lowermost Cenomanian (Shi et al., 2012), Tanai Village, Hukawng Valley, northern Myanmar. Diagnosis. As for the genus (vide supra). Description. Body coloration not preserved, 14.5 mm long. Head 0.87 mm long, 1.73 mm wide, eyes well separated; thorax 2.17 mm long; abdomen 11.2 mm long, 0.61 mm wide; with ovipositor clearly visible but short, not reaching the level of apex of abdomen. Wings uniformly hyaline; forewing ca. 8.1 mm long, 1.7 mm wide, 0.8 mm wide at nodus level; distance from base to arculus 1.9 mm, from arculus to nodus 1.2 mm; petiole very long and narrow, 1.6 mm long, 0.3 mm wide; distance from
base to Ax1 1.2 mm, from Ax1 to Ax2 0.8 mm, Ax2 just distal to arculus, no secondary antenodal crossvein distal of Ax2; antesubnodal space free; five preserved postnodal crossveins, well aligned with postsubnodal crossveins; pterostigma well preserved covering one cell, 0.4 mm long, 0.2 mm wide; base of RP3/4 below subnodus, base of IR2 one cell, 0.8 mm distally, that of RP2 two cells distal of that of IR2; base of IR1 three cells distally; area between RP and MA between arculus and subnodus free; no oblique crossvein; discoidal cell free, rectangular, with MAb of inverted obliquity; subdiscoidal space free, elongate, with posterior margin not fused with posterior margin of
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Fig. 4. Cretadisparoneura hongi gen. et sp. nov. NIGPAS161888, A, forewing; B, distal part of hind wing. Scale bar represents 2 mm.
wing; MA long ending below pterostigma; CuA very short; MP one cell long. Hind wing nearly identical to the forewing, except for the base of IR1 two cells distal of that of RP2, and MA ending on posterior wing margin below pterostigma instead of one cell distally. Discussion. Cretadisparoneura gen. nov. differs from the Burmese amber Mesosticta in the very short MP and the presence of only CuP in area between MP þ Cu and posterior wing margin in the petiole. An attribution of Cretadisparoneura to the coenagrionomorphan clade is supported by the following characters: absence of intercalary veins (except IR1 and IR2), and kink of RP1 at pterostigmal brace. Cretadisparoneura clusters with groups that have strongly shortened veins MP and CuA and a rectangular discoidal cell (viz. Palaeodisparoneurinae, Protoneurinae, Eoprotoneurinae, Caconeurinae, Disparoneurinae, Isostictidae, Platystictidae, and Lestoideidae). Isostictidae can be excluded because they have Ax2 basal of the arculus, the distal side of the pterostigma very oblique, and the subdiscoidal cell completely reduced. Platystictidae can be excluded because they have two crossveins in the petiole between
MP þ Cu and posterior wing margin, much longer wings with a falcate apex, a very long IR1, and unbraced pterostigmata (except in Neotropical Palaemnematinae) of very different shape, as well as a very different subdiscoidal area (rhomboid, triangular, or reduced). Only Drepanosticta polychromatica shows strong similarities with Cretadisparoneura, except in the base of IR2 close to subnodus instead of being two cells distally. The Lestoideidae can be excluded because they have much different pterostigmata (2.5 cells long, unbraced, and with oblique basal side) and a totally different branching pattern of the veins in the radial area (the nodus is midway between the recessed midfork and the origin of RP2, and there are three long intercalary veins between RP1 and RP2), as well as a completely reduced subdiscoidal cell. The Cretaceous Eoprotoneurinae share with Cretadisparoneura the base of RP3/4 aligned with subnodus, but they differ from it in the reduced subdiscoidal cell, and longer pterostigma. Within the Neotropical Protoneuridae, some genera have a greatly shortened MP, but this vein still extends at least over 2e3 cells. Some Protoneuridae, like Junix, also have a distinctly kinked RP1 at the pterostigmal brace and the origin of RP3/4 very close to subnodus, but differ in some other characters (e.g. origin of IR2 below subnodus).
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The Caconeurinae can be excluded because they have a venation that is very similar to Platystictidae, with very long IR1, and long MP. Cretadisparoneura differs from the Burmese amber Palaeodisparoneurinae (Hemidisparoneura and Palaeodisparoneura) in the base of RP3/4 below subnodus instead of being distinctly basal and base of IR2 well distal of subnodus. The modern Disparoneurinae show the closest similarities with Cretadisparoneura. Thus we provisionally include it in this subfamily. It differs from the modern genera Isomecocnemis, Disparoneura, Arabineura, and Elattoneura in the very short MP. Cretadisparoneura shares with Chlorocnemis the base of RP3/4 aligned with subnodus and very short MP, but it differs from this genus in the base of IR2 well distal from subnodus, and the distinctly shorter IR1 (Münz, 1919). Cretadisparoneura differs from Nososticta and Prodasineura in the presence of the subdiscoidal cell posteriorly closed (Cowley, 1936). 4. Conclusion The present discoveries of putative Platystictidae and Disparoneurinae in layers dated around 100 Ma is congruent with the hypothesis of Davis et al. (2011) who proposed estimated ages for the first appearance (MRP) of 125 Ma for the Platystictidae and of 112 Ma for the Platycnemididae, on the basis of a molecular phylogenetic analysis supported by an extensive use of the Odonata fossil record. Together with the presence of the Palaeodisparoneurinae in the same amber, these fossils suggest rapid diversifications of these families around 110e100 Ma. Acknowledgments HDY would like to thank National Basic Research Program of China (2012CB821903), Outstanding Youth Foundation of Jiangsu Province (BK 2012049), and the National Natural Science Foundation of China (91114201) for fund supporting. This paper is a contribution to the team project “Biodiversity: Origin, Structure, Evolution and Geology” granted to DA by the Lebanese University. We sincerely thank two anonymous referees for their useful remarks on the first version of the paper. References €der der rezenten Bechly, G., 1996. Morphologische Untersuchungen am Flügelgea Libellen und deren Stammgruppenvertreter (Insecta; Pterygota; Odonata), unter besonderer Berücksichtigung der Phylogenetischen Systematik und des € blingen Special Volume 2, 402. Grundplanes der Odonata. Petalura, Bo Bechly, G., 2007. Chapter 11.5 Odonata: damselflies and dragonflies. pp. 184e222. In: Martill, D., Bechly, G., Loveridge, R. (Eds.), The Crato fossil beds of Brazil: Window into an ancient world. Cambridge University Press, Cambridge, p. 624. Bechly, G., 2014. Phylogenetic systematics of Odonata. - homepage on the Internet. http://www.bernstein.naturkundemuseumbw.de/odonata/phylosys.htm. Bridges, C.A., 1994. Catalogue of the family-group, genus-group and species-group names of the Odonata of the World, Third edition. Bridges C.A. (publisher), Urbana, Illinois, USA, p. 950. Carle, F.L., Wighton, D.C., 1990. Chapter 3. Odonata. pp. 51e68. In: Grimaldi, D.A. (Ed.), Insects from the Santana Formation, Lower Cretaceous, of Brazil, Bulletin of the American Museum of Natural History, 195, pp. 1e191.
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