Apertoma 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) : -

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

Xyelotoma Gao * Ren & Shih* 2009; Ann. Entomol. Soc. Am. 102(4)* p. 589* fig. 1 (partim* only for Xyelotoma macroclada Gao * Ren & Shih* 2009).

Fossil sawflies from China and Germany • 13

Type species: Apertoma (Xyelotoma) macroclada Gao * Ren & Shih* 2009.

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

Included species: ºype species only.

Diagnosis: Forewing with pterostigma medium wide* sclerotized. Sc with stalk distant from R* ending at R well before free Sc 1 * the latter forming oblique crossvein. 1-Rs present* short. 1-M much longer than 2-Cu. Cell 1mcu long* with its upper side three times as long as 1m-cu.

Remarks: Under the present concept of Blasticotomidae * the type species cannot be included in Xyelotoma and is assigned to Apertoma gen. nov. in the subfamily Undatominae because of 1-Cu bent and cell 1mcu long and widened apically. These characters* together with M+Cu aligned with 1-Cu* are characteristic of Undatominae . Within that subfamily* the new genus is unique in the form of Sc splitting into stalk ending to R* and crossvein-like Sc 1 well distant from the stalk. For additional details* see the key below.

Key to genera of Blasticotomidae by forewing venation (excluding Zippelia engeli Rasnitsyn & Müller * 2023* known from a larva only)

1. Cu without distinct kink at fork M+Cu .....................................................................................................................................................2

- Cu with distinct kink at fork M+Cu......................................................................................................................................................... 16

2. 1-Cu straight; cell 1mcu scarcely or not at all widened distally and almost streamlined with wing axis* usually short (≤2:1). (Subfamily Blasticotominae Thomson * 1871) .........................................................................................................................................3

- 1-Cu distinctly bent; cell 1mcu usually distinctly widened apical* oriented oblique* usually long (>2:1). (Subfamily Undatominae subfam. nov.)................................................................................................................................................................... 10

3. 2-Rs lost* Sc lost* pterostigma wide* antennal thread (flagellum behind composite first segment) with one or no segments... ............................................................................................................................................................................................................................4

- 2-Rs present* Sc rarely lost* pterostigma variable* antennal thread with several segments..............................................................7

4. 2r-rs and 2m-cu on about one level. Cell 1mcu as long as cell 2mcu...................................................................................................5

- 2r-rs more basal than 2m-cu. Cell 1mcu distinctly shorter than cell 2mcu ........................................................................................6

5. Pterostigma particularly wide (0.9 as wide as cell 1mcu). Vein 2r-m about as long as vein 2r-rs .................................................... .................................................................................................................................................................................... Enspeletoma gen. nov.

- Pterostigma less wide (0.7 as wide as cell 1mcu). Vein 2r-m shorter than vein 2r-r............................... Blasticotoma Klug * 1834

6. Cell 3r 1.3 times as long as cell 2r..................................................................................................................... Paremphytus Brues * 1908

- Cell 3r scarcely longer than cell 2r........................................................................................................................ Runaria Malaise * 1931

7. Pterostigma very wide (~2:1). Sc lost .......................................................................................................................................................... .................... Leridotoma Rasnitsyn & Ansorge* 2000 (including ‘ Undatoma’ rudgwickensis Rasnitsyn & Jarzembowski * 1998)

- Pterostigma less wide (>2.5:1). Sc usually present .................................................................................................................................8

8. Sc complete except hind branch* with stalk touching R .............................................................. Abrotoma Gao * Ren & Shih* 2009

- Sc in two parts (stalk disconnected with crossvein-like Sc 1) or stalk lost ...........................................................................................9

9. Pterostigma wider (~3:1)* sclerotized. Cell 1mcu longer (2.5:1)......................................................... Xyelotoma Rasnitsyn * 1968

- Pterostigma narrower (4:1)* usually translucent centrally. Cell 1mcu shorter (<2:1) ...................................................................... ......................................................... Xyelocerus Rasnitsyn * 1968 ( Xyelocerus abruptus Sun * Rasnitsyn* Zhuang & Shih sp. nov.)

10. R+M long* Sc crossvein-like* pterostigma narrow (3.5:1) ..................................................... Synaptotoma Gao * Ren & Shih* 2009

- 1-Rs present even if short (no R+M)* Sc not as crossvein only* pterostigma usually wider (≤3:1) ........................................... 11

11. Sc lost ................................................................................................................................................................. Undatoma Rasnitsyn * 1977

- Sc with at least stalk distinct ...................................................................................................................................................................... 12

12. Sc stalk ending on R (no distinct Sc 2) ..................................................................................................................................................... 13

- Sc forked apical into Sc 1 and Sc 2 ............................................................................................................................................................... 14

13. Sc 1 lost. Cell 1mcu shorter* with its upper side two times as long as 1m-cu......................................................................................... .................................................................................................................................................... Aethotoma Gao * Shih* Engel & Ren* 2016

- Sc 1 present. Cell 1mcu longer* with its upper side three times as long as 1m-cu............................................................................ 15

14. Sc 1 started at end of Sc stalk................................................................................................................................... Aduantoma gen. nov.

- Sc 1 and apex of Sc stalk far distant............................................................................................................................ Apertoma gen. nov.

15. Sc with Sc 1 broken midway and with no adventitious basal hind branch ........................ Paradoxotoma Gao * Ren & Shih* 2009

- Sc complete and with adventitious basal hind branch ....................................................................................... Liberitoma gen. nov.

16. Cell 1mcu long (2.5:1)* scarcely or not at all widened distally and oriented less oblique with wing axis; Sc with stalk and fore branch complete; 1-Rs distinct. ( Pseudoxyelocerinae subfam. nov.) ............................................................................................... ............................................................................................................................. Pseudoxyelocerus Nel * Petrulevicius & Henrotay* 2004

- Cell 1mcu short (≤2:1)* scarcely or not at all widened distally and oriented strongly oblique with wing axis ( Dahurotomidae subfam. nov.) .............................................................................................................................................................................................. 17

17. 1-Rs distinct* Rs 2 present* Sc with stalk and both main branches complete .................................... Pseudoxyela Rasnitsyn * 1968

- 1-Rs and Rs

2

lost* Sc stalk* if present* disconnected from crossvein-like Sc

1

.................................. Dahurotoma Rasnitsyn * 1990