Oxfordgomphus trescellulae Huang & Nel, 2023

Huang, Di-Ying, Xu, Min-Min, Zhao, Qian, Gao, Jian & Nel, André, 2023, New stem-anisopteran dragonflies in the Jurassic of China (Odonata: Epiproctophora), Zootaxa 5396 (1), pp. 26-34 : 30-32

Oxfordgomphus trescellulae Huang & Nel sp. nov.

urn:lsid:zoobank.org:act:15C1AF17-A570-420B-8D4D-060DF148CE16

Figures 3 –4

Etymology. Named after the subdivision of the discoidal triangle into three smaller cells.

Material. Holotype NIGP202929 (part and counterpart of the basal fourth of a forewing), housed in the Nanjing Institute of Geology and Palaeontology, CAS, Nanjing, China.

Age and outcrop. Earliest Late Jurassic (Oxfordian); uppermost part of Yangshuzhuang Formation near Anyao Village, Chengliu Township, Jiyuan City, Henan Province, China.

Diagnosis. As for the genus by monotypy.

Description. Basal fourth of a forewing, apparently hyaline, fragment 11.6 mm long, wing 7.4 mm wide at level of discoidal triangle; distance from base to arculus 5.6 mm, from base to Ax1 4.3 mm; Ax2 opposite distal side of discoidal triangle, 4.6 mm distad Ax1; Ax2 obliquely directed; two secondary antenodal crossveins between Ax1 and Ax2, no antenodal basad Ax1, three distad Ax2; arculus angular; RP and MA well separated in arculus; two crossveins between RA and RP above discoidal triangle; four preserved crossveins between RP and MA; hypertriangle 3.4 mm long, 0.6 mm wide, short, free, with basal part of MA straight; short distance between arculus and basal side of discoidal triangle, 0.6 mm apart; anterior side of discoidal triangle ending at distal angle of hypertriangle; discoidal triangle equilateral, divided into three smaller cells; sides of discoidal triangle 2.9 mm long; postdiscoidal area with two rows of cells just distad discoidal triangle; median and submedian spaces free; CuP distinctly curved, situated at the point where AA is posteriorly curved; subdiscoidal space basally closed by CuP rather than by a PsA, acutely triangular, and crossed by two-three irregularly curved crossveins; a rather broad elongate cell situated below subdiscoidal space in anal area.

Remarks. Although fragmentary, this forewing base shows characters of the two families Liassogomphidae Tillyard, 1935 and Juragomphidae , viz. a CuP distinctly curved and distally displaced at the point where AA is posteriorly curved, subdiscoidal space basally closed by CuP rather than by a PsA, acutely triangular, and crossed by two-three irregularly curved crossveins; a rather broad elongate cell situated below the subdiscoidal space; a short hypertriangle with base of discoidal triangle very close to arculus; numerous crossveins in area between RP and MA basad fork of MA into MAa and MAb ( Nel et al. 1993; Etter & Kuhn 2000; Nel et al. 2001). The new fossil shares with Juragomphus Nel et al., 2001 an equilateral discoidal triangle as a putative synapomorphy, but this character is convergently present in some other Mesozoic Anisoptera , viz. in the Liupanshaniidae Bechly et al., 2001 (Aeshnoptera Bechly, 1996) and in the Aktassiidae Aktassiinae Pritykina, 1968 (Petalurida Bechly, 1996, Aktassia Pritykina, 1968 and Aeschnogomphus Handlirsch, 1906 ). The new fossil and Juragomphus differ from these taxa in the presence of a weak PsA, and of a curved CuP, vs. strong PsA and a straight CuP in the latter taxa ( Nel et al. 1998; Bechly et al. 2001). The Liassogomphidae have a more transverse discoidal triangle than in Juragomphus and the new fossil ( Bode 1953; Nel et al. 1993).

The new fossil and the Liassogomphidae differ from Juragomphus in the less numerous cells in the discoidal triangle and the postdiscoidal area, and in the less numerous antenodal crossveins.

Thus, the affinities of the new fossil with the Liassogomphidae vs. the Juragomphidae remain somewhat uncertain, although an attribution to the latter family could be more likely for a shared putative apomorphy. Thus we tentatively attribute it to this family, in a new genus and species.

Note. The Henrotayiidae Fleck et al., 2003 ( Henrotayia Fleck et al., 2003 known by a hind wing) is another Liassic anisopteran family sharing a subdiscoidal space similar to that of the new fossil but it strongly differs from it in the absence of antenodal crossveins of first row between C and ScP and a quite smaller discoidal triangle ( Fleck et al. 2003).

Figures

FIGURE 3. Oxfordgomphus trescellulae Huang & Nel, gen. et sp. nov., holotype NIGP202929, photographs. a, part; b, counterpart. Scale bars = 2 mm.