CAVILABIATA

Kohli, Manpreet Kaur, Ware, Jessica L. & Bechly, Günter, 2015, How to date a dragonfly: Fossil calibrations for odonates, Palaeontologia Electronica 19, pp. 1-14 : 7

CROWN CAVILABIATA (LIBELLULOIDEA SENSU LATO)

Node Calibrated: (7) Crown Cavilabiata . This node represents the suborder Cavilabiata .

Species. Juralibellula ningchengensis (Juralibelulidae) Huang and Nel, 2007

Specimen. NIGP 143439 (Nanjing Institute of Geology and Palaeontology, China): a thorax with four wings.

Phylogenetic Justification. This species was demonstrated by Huang and Nel (2007) to be nested within Cavilabiata as sister group to Neobrachystigmata. It shares the main wing venational apomorphies of Cavilabiata : distal part of antesubnodal area free of crossveins ("cordulegastrid gap"), basal part of CuA ("gaff") before its branching distinctly prolonged in hind wing, RP3/4 and MA slightly undulating; pterostigmata not parallel sided (distal side more oblique than basal side), and rather stout with length less than eight times width, forewing nodus shifted distinctly distal of midwing position; hind wing CuAa shortened, with only five posterior branches, anal loop elongated and enlarged with more than five cells. Furthermore, it shares several synapomorphies with more advanced Cavilabiata , which are absent in Cordulegastridae + Neopetaliidae : Pterostigmata short covering only 1–3 cells, distal area between RP2 and IR2 widened with at least two rows of cells, basal area between MP and CuA widened with at least two rows of cells in hind wing, terminal branch of CuAa secondarily branched on CuA.

Minimum Age. 168 Ma.

Age Justification. Found in Middle Jurassic Jiulongshan Formation (= Haifanggou Formation) near Daohugou village, Wuhua township, Ningcheng county, Chifeng city, Inner Mongolia, north-east China. As discussed above in the Anisoptera calibration age justification, the 168 Ma minimum age is derived from the age range of the overlying Daohugou Formation.

Discussion. According to Huang and Nel (2007) Juralibellula is relatively advanced and appears to be nested well within Cavilabiata , suggesting great antiquity for the clade as a whole. Cavilabiata is a well-supported node by both morphology and molecular data (e.g., ( Misof et al., 2001; Fleck et al., 2008; Letsch et al., 2009; Blanke et al., 2013). The presence of the apomorphic spoon-shaped labial mask supports the monophyly of this group. This group formerly referred to as Libelluloidea includes families: Chlorogomphidae , Neopetallidae, Cordulegastridae , Macromiidae , Cordullidae, Libellulidae and GSI (sensu Ware et al., 2007). Molecular divergence time estimates by Ware et al. (2007) and (2008) suggest a Cretaceous age for the Cavilabiata clade.