Itaphlebia elegana 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 elegana Cao, Shih & Ren sp. nov.

Figs 3 , 4 , 5

Etymology.

The specific name is from Latin adjective “elegans”, referring to the elegant body posture.

Type material.

Holotype: female, No. CNU-MEC-NN2008228 p/c (Fig. 3 ), preserved in lateral view, thorax partly preserved, abdomen well-preserved, with four wings partly preserved, veins of one forewing mostly discernible, veins of one hind wing relatively discernible. Paratypes: sex unknown, No. CNU-MEC-NN2015026 (Fig. 4 ), preserved in ventral view, thorax and abdomen partly preserved, only right forewing venation clearly discernible; female, CNU-MEC-NN2016020 p/c (Fig. 5 ), body nearly complete but not well-preserved, forewing venation partly 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.

On forewing, costal area slightly broad; Sc forking with three branches; Rs (R2 to R5) forking with five branches; R2+3 forking before the crossvein r3-r4; R4+5 forking before the crossvein r5-m1+2; crossvein cu1-cu2 near the forking of Cu1+M, and crossvein cu1-m4 far before M3+4 forking. Long and robust setae present on anal veins of forewing.

Description.

Mainly based on Holotype, unless indicated as paratype.

Thorax: Incompletely preserved, setae discernible.

Wing: Long and oval, basal part of the wing narrow, gradually broadening from the base toward the apex. Forewing with the basal part of C somewhat convex, anterior area slightly broad, pterostigma incompletely preserved; Sc with three branches, Sc1 and Sc2 ending at C before the middle of the wing length, Sc3 near pterostigmal area; Rs forking with five branches, one short crossvein sc-r before pterostigma, crossvein r1-r2 under the pterostigma, approximately near the forking of R2+3, crossvein r2+3-r4 before crossvein sc-r, oblique crossvein r3-r4 between R3 and R4, R2+3 four times as long as R4+5, R4 forking with two branches (R4a, R4b), oblique crossvein r5-m1+2 emerged after the forking of R4+5, crossvein r5-m1 present before the crossvein r4-r5; conspicuous thyridium at the forking of M; M with four branches, M3+4 divided beyond the forking of M1+2; straight crossvein m1+2-m3 forking at the middle length of M1+2; crossvein m-cu1 before the forking of M3+4; Cu1 coalesced with M for a relatively short distance and separated from M near the crossvein cu1-cu2; long and robust setae present on veins A1 and A2, A1 and A2 almost parallel; crossvein a1-a2 at the same level of Cu1; A3 absent. Hind wing shorter and broader than forewing; pterostigma preserved in hind wing. Sc simple, terminated at C in the first one third of wing; R1 under pterostigma and connecting with C by a short crossvein c-r1, Rs with four branches, two crossveins between R2+3 and R4. Anal margins in hind wings not preserved, several long and robust setae preserved.

Abdomen: With 11 visible abdominal segments, segments VIII-XI distinctly smaller than segment VII, a pair of cerci at the end of abdomen, each one with three segments, setae discernible.

Remarks.

Itaphlebia elegana sp. nov. demonstrates an individual aberration of the sixth branch of R vein by the forking of R4, providing a character for understanding the evolution of wing venation. Although the hind wing has R with five branches, the diagnosis of Itaphlebia should be revised to indicate that the forewing Rs forking with four or five branches. CNU-MEC-NN2008228 p/c has two crossveins between R1+2 and R3+4, but only one crossvein is visible in CNU-MEC-NN2016020 p/c and CNU-MEC-NN2016026 p/c. Considering these three specimens have many similarities regarding other characters, we regard them as the same species. The difference in crossveins between R2+3 and R4 might have been due to the intraspecific difference or inheritable mutations.

Measurements

(in mm). Holotype: female, No. CNU-MEC-NN2008228 p/c: Abdomen length 6.0, forewing length 9.4, hind wing length 7.5 (all as preserved). Paratypes: sex unknown, No. CNU-MEC-NN2015026: thorax length 1.8, thorax maximum width 1.1, forewing length 7.5, forewing maximum width 3.0 (all as preserved); female, CNU-MEC-NN2016020 p/c: head length 1.1 (excluding the antenna), head maximum width 0.8 (excluding the antenna), thorax length 2.2, thorax maximum width 1.7, forewing length 8.4, forewing maximum width 3.5 (all as preserved).

Figures

Figure 3. Itaphlebia elegana sp. nov., holotype, CNU-MEC-NN 2008228 p / c. A photograph of part B enlarged details of basal forewing of part, anal veins with long and robust setae (under alcohol) C enlarged details of basal hind wing of counterpart (under alcohol) D photograph of counterpart E line drawing of counterpart F Line drawing of forewing of part, anal veins with long and robust setae G line drawing of hind wing of counterpart. Scale bars: 1 mm (A-G).

Figure 4. Itaphlebia elegana sp. nov., paratype, CNU-MEC-NN 2015026 A photograph of paratype B enlarged details of base of right forewing (under alcohol) C enlarged details of base of left forewing (under alcohol) D line drawing of right forewing E line drawing of left forewing. Scale bars: 1 mm (A-E).

Figure 5. Itaphlebia elegana sp. nov., paratype, CNU-MEC-NN 2016020 p / c. A photograph of part of paratype B enlarged details of base of forewing of counterpart of paratype (under alcohol) C photograph of right forewing of part D photograph of left forewing and part of hind wing of part E line drawing of right forewing F line drawing of left forewing and part of hind wing. Scale bars: 1 mm (A-F).