Monoctonus Haliday, 1833

Davidian, Elena M. & Belokobylskij, Sergey A., 2025, Two new species of the genus Monoctonus Haliday, 1833 from the subtribe Monoctonina (Hymenoptera: Braconidae: Aphidiinae) from mountains of China, Zootaxa 5696 (4), pp. 590-596 : 591-595

Genus Monoctonus Haliday, 1833

Type species: Aphidius caricis Haliday, 1833

Both new species described herein from China ( Sichuan) belong to the Monoctonus nervosus species group, which is characterised (according to van Achterberg 1989) by the presence of 16–17 antennomeres in female, presence of the recurrent (m-cu) and first radiomedial (2-SR) veins in the fore wing, and also biotopical association with the hosts mainly from herbaceous plants.

According to recent molecular, morphological and trophic investigations, the M. nervosus species group is a mixed aggregation and comprises species with different numbers of antennomeres and labial palp segments, as well as variable shapes of the ovipositor sheath ( Čkrkić et al. 2019). The following species belong to this species group: M. allisoni Pike & Starý, 2003 ; M. brachyradius Čkrkić, Petrović & Tomanović, 2019 , M. canadensis Čkrkić, Petrović & Tomanović, 2019 , M. indiscretus Čkrkić, Petrović & Tomanović, 2020 , M. inexpectatus Čkrkić, Petrović & Tomanović, 2019 , M. leclanti Tomanović & Starý, 2002 , M. montenegrinus Petrović & Tomanović, 2023 , M. nervosus (Haliday, 1833) , M. pacificus Pike & Starý, 2000 , M. parvipalpus Čkrkić, Petrović & Tomanović, 2019 , and M. paulensis (Ashmead, 1902) ( Čkrkić et al. 2019, 2020).

Key to allied species of the genus Monoctonus

1. Antenna with 18 antennomeres. Propodeum with central areola delineated by carinae............................... 2

- Antenna with fewer antennomeres. Propodeum without central areola delineated by carinae.......................... 4

2. Notauli completely absent. Labial palpus 1-segmented.—Length of petiole 2.0 × its width at level of spiracles. Ovipositor sheath 3.6 × longer than its maximum width....................... M. parvipalpus Čkrkić, Petrović & Tomanović, 2019

- Notauli present in anterior 0.3 of mesoscutum. Labial palpus 3-segmented........................................ 3

3. Length of petiole 2.6 × its width at level of spiracles. Ovipositor sheath 4.0 × longer than its maximum width........................................................................... M. montenegrinus Petrović & Tomanović, 2023

- Length of petiole 2.0 × its width at level of spiracles. Ovipositor sheath 3.2 × longer than its maximum width.................................................................................................. M. genriki sp. nov.

4. Antenna with 16 antennomeres. Length of petiole 2.5 × its width at level of spiracles. Ovipositor sheath 2.6 × longer than its maximum width.................................................................... M. sichuanicus sp. nov.

- Antenna with 11 antennomeres. Length of petiole 1.5–2.0 × its width at level of spiracles. Ovipositor sheath 3.0 × longer than its maximum width............................................................... M. hispanicus Tizado, 1992