Itaphlebia procera Cao, Shih & Ren, 2022

Cao, Yizi, Lin, Xiaodan, Shih, Chungkun & Ren, Dong, 2022, Two new species of Itaphlebia (Insecta, Mecoptera, Nannochoristidae) from the late Middle Jurassic of China, ZooKeys 1108, pp. 175-188 : 175

Itaphlebia procera Cao, Shih & Ren sp. nov.

Figs 1 , 2

Etymology.

The specific name is derived from the Latin adjective “procerus”, indicating the relatively large body size.

Type material.

Holotype: sex unknown, No. CNU-MEC-NN2009273 (Fig. 1 ), preserved in dorsal view, head and thorax well-preserved, with four wings partly preserved, veins of right forewing mostly discernible. Paratype: sex unknown, No. CNU-MEC-NN2009168 (Fig. 2 ), preserved in lateral view, body partly preserved, only one forewing venation clearly discernible.

Locality and horizon.

All specimens were collected from the Jiulongshan Formation, latest Middle Jurassic age (Bathonian-Callovian boundary interval) from Daohugou Village, Ningcheng County, Inner Mongolia Autonomous Region in China.

Diagnosis.

Body size ca 10 mm. On forewing, Sc forking with three branches; R2+3 forking before M1+2; crossvein r4-r5 before crossvein r5-m1; Cu1+M forking before the crossvein cu1-cu2; and crossvein cu1-m4 after M3+4 forking.

Description.

Mainly based on Holotype, unless indicated as paratype.

Head: Oval with large compound eyes. Antenna partially preserved, filiform with 33 and 27 segments as preserved respectively. Vertex of the head raised, mouthparts long and slender.

Thorax: Long and relatively well-preserved, pronotum (width 0.5 mm, length 0.25 mm), mesonotum (width 1.5 mm, length 1.25 mm), metanotum (width 1.25 mm, length 1.4 mm) and scutellum (heavy shadowed) clearly discernible.

Leg: Leg barely preserved and slender, tibia longer than femur, surfaces of all legs densely covered with short and irregularly arranged setae.

Wing: Forewing: Long and oval, basal part of the wing narrow, gradually broadening from the base toward the apex. Right forewing with the anterior area broad, a distinct pterostigma present; Sc with 3 branches, Sc1 and Sc2 ending at C before the middle of the wing length, Sc3 terminated at C right near pterostigmal area; R forking before Sc2, Rs forking with 4 branches, one short crossvein sc-r before pterostigma, crossvein r1-r2 under the pterostigma, approximately near the forking of R2+3, crossvein r3-r4 after the level of the crossvein r1-r2, R2+3 4 times as long as R4+5, crossvein r5-m1+2 emerged after the forking of R4+5, oblique crossvein r5-m1 present after the crossvein r4-r5; conspicuous thyridium at the forking of M; M with 4 branches, M3+4 divided beyond the forking of M1+2; straight crossvein m1+2-m3 between M1+2 and M3, near the forking of M1+2; crossvein m-cu1 after the forking of M3+4, somewhat S-shaped; Cu1 coalesced with M for a long distance and separated from M after the crossvein cu1-cu2; A1 and A2 are almost parallel; crossvein a1-a2 after the level as the base of Cu1; A3 absent. Hind wing: Shorter than forewing; the pterostigma slightly darkened. Sc simple, terminated at C in the first one third of wing, one crossvein c-r1 present at half-length of hind wing; R1 under pterostigma and connected with C by a short crossvein c-r1; posterior and anal margins in hind wings not preserved.

Abdomen: With six visible large abdominal segments, segments II-IV and segment VI distinctly smaller than segment V, the distal segments not preserved.

Remarks.

The new species shows great differences from other species of Itaphlebia in having relatively moderate body size, a broader thoracic notum and the presence and position of the crossvein r5-m1 that is in a more distal position than in other species, which is also a new finding for nannochoristid venation. So far, we have found two specimens of the new species, of which characters appear to be stable and therefore sufficient for establishing a new species.

Measurements

(in mm). Holotype: No. CNU-MEC-NN2009273: head length 0.7 (excluding the antenna), head maximum width 1.0 (excluding the antenna), thorax length ca 3.0, thorax maximum width 1.9, forewing length 9.4, hind wing length 7.5 (all as preserved). Paratype: No. CNU-MEC-NN2009168: forewing length 11.5, forewing maximum width 4.4 (all as preserved).

Figures

Figure 1. Itaphlebia procera sp. nov., holotype, CNU-MEC-NN 2009273 A photograph of holotype B line drawing of holotype C line drawing of right forewing D photograph of right wing. Scale bars: 1 mm (A-D).

Figure 2. Itaphlebia procera sp. nov., paratype, CNU-MEC-NN 2009168 A photograph of paratype B photograph of wings C line drawing of forewing. Scale bars: 1 mm (A-C).