Liberitoma Sun, Rasnitsyn, Zhuang & Shih, 2024

Sun, Chenhui, Rasnitsyn, Alexandr P., Wedmann, Sonja, Zhuang, Jialiang, Shih, Chungkun, Ren, Dong & Gao, 2024, Revisions * new taxa * and venation transformations of the sawfly family Blasticotomidae sensu lato (Hymenoptera: ºenthredinoidea) highlight the evolution of the basal Hymenoptera, Zoological Journal of the Linnean Society 202 (1) : -

Liberitoma Sun, Rasnitsyn, Zhuang & Shih gen. nov.

Type species: Liberitoma tenella Sun * Rasnitsyn* Zhuang & Shih sp. nov. http://zoobank.org/ urn:lsid:zoobank.org:act:470D88B3-89FE-45AF-937E-41D9D4A49581

Etymology: The generic name is a combination of the Latin ‘liber-’* meaning free and unfettered* referring to the unique triple-branched Sc in the forewing* and ‘-toma’ from the type genus Undatoma Rasnitsyn * 1977. Gender feminine.

Included species: Besides the type species* Liberitoma compta Sun * Rasnitsyn* Zhuang & Shih sp. nov. and Liberitoma incompleta Sun * Rasnitsyn* Zhuang & Shih sp. nov.

Diagnosis: Antenna with thread four-segmented as preserved* at least one-third as long as first flagellomere. Forewing with pterostigma wide* sclerotized; Sc complete (with stalk and apical fork) and additionally with secondary hind branch basal to Sc 2 * all branches ending before 1-Rs separation; 1-Rs developed; 1-M longer than 2-Cu. Hind wing with Sc two-branched and with series of basal hamuli.

Remarks: The most important character supporting the new genus at a generic level is the unique presence of an additional hind branch of Sc* a characteristic seemingly unparalleled in any other hymenopterans. Yet we consider it as a stabilized character of diagnostic value rather than an individual variation because it is visible in all specimens available with the respective wing part preserved.

Liberitoma tenella Sun, Rasnitsyn, Zhuang & Shih gen. et sp. nov. ( Fig. 3) http://zoobank.org/ urn:lsid:zoobank.org:act:5896464E-D0A3-480B-8E32-EB0477BAC53F

Diagnosis: Antenna with the remaining filament part at least half as long as the first flagellomere; length-to-width ratio of each segment ~4:1. Forewing with the basal branch of Sc and Sc 2 short* vertical* and the basal branch joining with R far from 1-M base; Sc

1

long* curved; Sc

2

meeting R slightly before 1-M base.

Etymology: The species name is derived from the Latin word ‘tenellus’* meaning weak* referring to the slim flagellum.

Material: Holotype * CNU-HYM-NN2022301.

Locality and horizon: Latest Middle Jurassic (late Callovian)* Jiulongshan Formation; Daohugou Village* Wuhua ºownship* Ningcheng County* Chifeng City* Inner Mongolia * China.

Description: Holotype * CNU-HYM-NN2022301 ( Fig. 3A * B). Sex unknown. Body length (excluding antenna) 13.9 mm; forewing nearly complete* head* thorax* part of legs* and antennae preserved. Surface sculpture coarsely punctated* especially on head* thorax* and the first abdominal segment. Abdomen with eight segments preserved.

Head: Short* ovate* with eyes small* roundish* not bulging* placed near to head fore margin.

Antenna: The right antenna well preserved; the first flagellomere (fla 1 * 2.1 mm) slightly shorter than the width of head (2.6 mm)* gradually thickening towards apex* and about two times as long as thread. Thread with six segments preserved* length (in millimetres) of each flagellomere: 0.31* 0.26* 0.22* 0.20* and 0.17 (the length of the last flagellomere was not measured owing to partial preservation)* and length to width ratio of each flagellomere ~4:1 ( Fig. 3C).

Forewing: Length 12.3 mm as preserved; vein Sc sub-parallel to R * with basal branch and Sc 2 vertical* very short; Sc 1 curved* much longer; basal branch joining with R prior to 1-M base almost for the length of cell 1r; Sc 2 merging into R a short distance after 1-M base; Sc 1 much longer than 1-Rs ( Fig. 3D). Pterostigma wide* fully sclerotized. Vein M+Cu bent* Cu with no distinct kink at M+Cu fork. Vein 1-M (1.1 mm) ~3.5 times as long as 1-Rs (0.3 mm) and weakly arching towards anterior margin. 1-Cu distinctly bent. Cell 1mcu distinctly widened apically* oblique and long. Crossvein 2r-rs (1.1 mm) about three times as long as 1r-rs (0.3 mm)* oblique and meeting pterostigma only near its apex. Cell 2r receiving 2r-m at about two-thirds of its length. Cell 1r large* 2r and 2rm narrow and equal in width* 2rm wide and shaped like a regular quadrangle* 1mcu long.

Hind wing: Partly preserved* with a row of basal hamuli ( Fig. 3E). Sc with two branches ending well before end of costal space; Sc 1 long* bent; Sc 2 short* vertical.

Legs: Right foreleg and both hind legs partly preserved; all surfaces of legs covered by numerous fine setae. Protibia 2.7 mm long* with only one spur visible; tarsus very long* lengths (in millimetres) of tarsomeres: 1.37* 0.87* 0.65* 0.37* and 0.69* respectively; tarsal claw strongly bent. Hind femora moderately thick* hind tibia rather thick* 3.9 mm long.