Spathius brevicaudis Ratzeburg, 1844 (new record in China mainland)

Cao, Liang Ming, Zhang, Yan Long, van Achterberg, Cornelis, Wang, Zhi Yong, Wang, Xiao Yi, Zhao, Wen Xia & Yang, Zhong Qi, 2019, Notes on braconid wasps (Hymenoptera, Braconidae) parasitising on Agrilus mali Matsumura (Coleoptera, Buprestidae) in China, ZooKeys 867, pp. 97-121 : 97

Spathius brevicaudis Ratzeburg, 1844 (new record in China mainland) Figures 15 , 16 , 17 , 18

Spathius brevicaudis Ratzeburg, 1844: 49; Nixon, 1943: 202; Belokobylskij, 1996: 188.

Material examined.

1♀, 1♂, China, Xinjiang Province, Gongliu City, Mohuer County, 26.VI.2006, 1325 m altitude, 43°13'25"N, 82°45'16"E, Zhang YanLong, Wang ZhiYong & Yang ZhongQi leg., 12.VII.2006, hatched out from mature larvae of A. mali .

Redescription.

Body length, ♀/♂ = 2.9/2.8 mm; forewing length, ♀/♂ = 2.34/2.25 mm.

Colour (Female).

Head dark brown, basal half of antenna yellow, its apical half brown; mesoscutal lobes, scutellum dark brown, pronotum brown; metasoma dark brown except first and second metasomal segments, basal portion of third metasomal segment yellow; fore wing partly weakly darkened; legs yellow ( Fig. 15A, B ).

Head.

Median length 0.7 times of its width in dorsal view; vertex broad, surface rough, with low (fine) sculptures and rare white setae ( Fig. 15D ); length between posterior margin of lateral ocellus and occipital carina half of head length in dorsal view; occipital carina median portion concave, reversed V-shaped ( Fig. 15D ); length of eye: length of temple in dorsal view = 4.3: 4; eyes small, slightly protruding bilaterally; OOL: OD: POL = 3: 1: 1.8; ocellar area distinctly differentiated, slightly swollen; width of head 1.1 times of height in front view, distance between eyes 1.3 × height of eye ( Fig. 15C ); face distinctly and irregularly striate, covered with white setae; malar space 0.6 × height of eye; height of clypeus 0.4 × its width, exterior margin of clypeus straight; basally mandible broad, apical portion black, blunt and robust; hypoclypeal depression deeply concave; antenna 28 segmented, scape twice length of first flagellar segment, and twice its maximum width; first flagellar segment 5.3 × its maximum width, as long as second flagellar segment; last antennal segment acute apically.

Mesosoma.

Length of mesosoma 1.9 × its width and 1.6 × its height in lateral view ( Fig. 16A ); pronotal depression with short carinae; mesoscutum distinctly elevated above pronotum ( Figs 15D , 16A ). Mesoscutum nearly equilateral triangular, median length 0.9 × its maximum width; median and lateral lobes of mesoscutum with scaly sculpture; notauli and centre of mesoscutum deep and light-coloured with strong carinae ( Fig. 15D ); mesopleuron distinctly striate in upper 1/3 near pronotum and tegula, posterior 2/3 with scaly sculpture, epicnemial carina bent, episternal area taproot-shaped ( Fig. 16A ). Precoxal sulcus broad, length 1.67 × its width, with four longitudinal carinae inside. Scutellum flat and triangular, apical 1/3 of scutellum with scaly sculpture; scutellar sulcus 1/3 of scutellum length, with seven longitudinal carinae and separated small concave depressions; metanotum broad, dorsally concave, laterally with several longitudinal carinae, posterior margin slightly curved; propodeum weakly oblique posteriorly (lateral view), with scaly sculpture, medio-longitudinal carina bifurcates at basal third, posterior half of propodeum with irregular carinae.

Legs.

Fore femur 0.8 times as long as fore tibia and 3.75 times as long as its width, fore tibia 8.0 times of its width, outside with a row of spines and apex with comb of spines, ratio of fore tarsal segments I–V = 1.4:0.7:0.5:0.3:0.6; mid femur 0.8 times of mid tibia, ratio of mid tarsal segments I–V = 7:5:4:5:7; hind femur 2.7 times of its width, 0.8 times as long as hind tibia, ratio of hind tarsal segments I–V =1.5:0.8:0.5:0.4:0.8 ( Fig. 17A ).

Wings.

Fore wing with faintly brown along veins in basal half, apical half of fore wing largely subhyaline, its length 3.2 times of width; pterostigma 4.0 times as long as its maximum width; vein 1-R1 1.3 times of pterostigma, vein r originates at middle of pterostigma; vein SR1 8.5 times as long as vein r and straight; vein r nearly 1/4 of vein 2-SR, vein cu-a perpendicular to vein CU1, vein m-cu enters second submarginal cell; meeting point of veins 2-SR, 2-M and 2-SR+M finely sclerotised, veins reduced; vein 1-SR+M straight, vein 1-SR 1/3 length of vein 1-M; vein r-m weakly sclerotised, nearly invisible; veins 3-M and CU1a extending to wing margin ( Fig. 16C ). Length of hind wing 5.0 × its width ( Fig. 16D ).

Metasoma.

First tergite length 1.55 × its maximum apical width in dorsal view, apical 2/3 with regular longitudinal striae, basal 1/3 rugulose; in lateral view first tergite very robust, spiracular tubercles located at basal 1/4, laterally with erect white long setae, apical 1/3 of laterotergites visible; second tergite largely rugulose and with several large round yellow spots; basal 2/3 of third tergite striate-rugulose, apical 1/3 smooth; fourth tergite basally 1/4 with longitudinal rugulosity; fifth and sixth tergites smooth. Length of setose part of the ovipositor sheath 0.7 × length of metasoma, 0.38 × length of fore wing, and 0.3 × length of body ( Figs 16B , 17B ).

Male.

Body length 2.8 mm, otherwise similar to female ( Figs 17C , 18 ), but pigmentation and metasomal sculpture more developed than in female.

Distribution.

China (Xinjiang, Taiwan); Austria; Azerbaijan; Bulgaria; Czech Republic; Denmark; France; Georgia; Germany; Hungary; Italy; Japan; Kazakhstan; Korea; Moldova; Mongolia; Poland; Romania; Russia; Slovakia; Sweden; Switzerland.

Host.

Larva of Agrilus mali (new record), Agrilus viridis (Linnaeus), Anthaxia manca Linnaeus, A. quadripunctata (Linnaeus), Bostrichus bidens Fabricius ( Buprestidae ); Acanthocinus griseus (Fabricius), Arhopalus coreanus Sharp, Exocentrus lusitanus (Linnaeus) ( Cerambycidae ); Blastophagus minor (Hartig), B. piniperda (Linnaeus), Carphoborus minimus (Fabricius), Ceutorhynchus quadridens (Panzer), Dryocoetes autographus (Ratzeburg), Hylesinus fraxini Panzer, Ips acuminatus (Gyllenhal), I. typographus (Linnaeus), Lixus bidens Fabricius, Magdalis frontalis Gyllenhal, M. violacea (Linnaeus), Niphades variegatus Roelofs, Onthotomicus angulatus Eichhoff, Phloeotribus rhododactylus (Marsham), Pissodes notatus Fabricius, P. obscurus Roelofs, Pityogenes bidentatus (Herbst), P. chalcographus (Linnaeus), Pityophthorus micrographus (Linnaeus), Polygraphus subopacus Thomson, Rynchaenus fagi (Linnaeus), R. pilosus Fabricius, R. quercus (Linnaeus) R. salicis (Linnaeus), R. testaceus Muller, Scolytus intricatus (Ratzeburg), S. koenigi Schewyrew, S. laevis Chapuis, S. mali (Bechstein), S. multistriatus (Marsham), S. rugulosus (Muller), Shirahoshizo insidiosus Roelefs, Sh. pini Morimoto, Sh. rufescens Roelofs ( Curculionoidea); Xiphydria longicollis (Geoffroy) ( Xiphydriidae ).

Remarks.

Among all the parasitoids of A. mali we found in the past years, only two specimens of S. brevicaudis were recorded, which indicates that it is an occasional parasitoid of this host. This species is here recorded as new for continental China, after Belokobylskij (1996) reported it from Taiwan. Its identification is based on Ratzeburg’s original description, Nixon’s redescription, and reared material from Europe seen by the second author. S. brevicaudis may be confused with S. rubidus (Rossi), but S. brevicaudis has vein M+CU1 of fore wing straight or nearly so (weakly to moderately sinuate in S. rubidis ), wing membrane with a faintly infuscate patch or band below pterostigma (with a distinct dark patch or band below pterostigma, rarely reduced in small specimens) and basal pale spot of pterostigma weakly differentiated (basal pale spot of pterostigma distinctly differentiated in dark specimens). Although, the differences are minor , all related to the fore wing and sometimes gradual, we prefer to recognise S. brevicaudis as separate species till molecular data will become available. The main reason for this is that reared series show these minor differences to be stable enough for separation both species in north-western Europe.

Figures

Figure 15. Spathius brevicaudis ♀ A Habitus, dorsal view B Habitus, lateral view C Head, anterior view D Head and mesosoma, dorsal view.

Figure 16. Spathius brevicaudis ♀ A Head and mesosoma, lateral view B Metasoma, lateral view C Fore wing D Hind wing.

Figure 17. Spathius brevicaudis A ♀, Left hind leg, lateral view B ♀, metasoma, dorsal view C ♂, habitus, dorsal view.

Figure 18. Spathius brevicaudis ♂ A Head, frontal view B Head and mesosoma, lateral view C Head and mesosoma, dorsal view D Metasoma, dorsal view.