Melittobia sosui Dahms, 1984

Pham, Ph. H., Nguyen, H. T., Nguyen, T. M., Truong, X. L. & Nguyen, Q. C., 2023, Redescription of the parasitic wasp Melittobia sosui Dahms, 1984 (Hymenoptera: Eulophidae), with records on its new hosts in Vietnam, Russian Entomological Journal 32 (2), pp. 181-186 : 183-186

Melittobia sosui Dahms, 1984

Figs 8–20 .

Melittobia sosui Dahms, 1984: 302 , ♂, ♀. Holotype ♂, Japan: Okinawa Isl., Ryuku Arch. (Kyushu University, Kyushu , Japan).

MATERIAL EXAMINED. VIETNAM: Thai Binh: 134♀♀, 4♂♂, Hong Minh, Hung Ha, 14.vi.2022, found in a nest of Ch. bengalense (Dahlbom) , Coll. P. H. Pham. Ha Noi: 617♀♀, 16♂♂, Co Nhue, Bac Tu Liem, 4.xii.2021, 1.i.2023, 7.i.2023, emerged from two overwintering nests of S. madraspatanum and a pupa of D. melanogaster, Coll. P. H. Pham and Khuc Thi Ut ; 442♀♀, 34♂♂, Van Hoa, Ba Vi, 8.i.2020, found parasitizing on a prepupa of a nest of A. chinense and on a prepupa of a nest of Ch. japonicum, Coll. P. H. Pham. Hoa Binh: 217♀♀, 7♂♂, My Tan,Tan Thanh,Luong Son, 20.iii.2019, 27.vi.2019, 26.vii.2019, found in a cocoon of Ch. malignum and in a nest of Megachile disjuncta (Fabricius, 1781) , Coll. P. H. Pham and Khuc Thi Ut; 37♀♀, 3♂♂, Kim Son, Kim Boi, 22.ix.2019, Coll. P. H. Pham; 72♀♀, 2♂♂, Thanh Lap, Luong Son, 2.ix.2020, found in a pupa of D. melanogaster, Coll. P. H. Pham ; 288♀♀, 10♂♂, Khai Doi, Kim Boi, found in nests of E. architechtus, Coll. P. H. Pham. Bac Ninh: 138♀♀, 6♂♂, Tan Hong, Tu Son, 2.iii.2017, 14.ii.2019, found in old nests of S. madraspatanum and in a cocoon of A. troglodytes put in an old nest of S. madraspatanum, Coll. P. H. Pham. Thai Nguyen: 212♀♀, 4♂♂, Phu Luong, 8.ix.2019, 17.vii.2020, found in cocoons of Isodontia sp. in trap nests and of Ch. malignum in trap nests, P. H. Pham. Vinh Phuc: 2♀♀, Me Linh Station for biodiversity, Ngoc Thach, Me Linh, 31.v.2019, found in a nest of S. deforme, P. H. Pham. Quang Ninh: 81♀♀, Hai Ha town, Hai Ha, 24.i.2018, found in a nest of S. madraspatanum, Coll. P. H. Pham. Cao Bang: 203♀♀, 6♂♂, Ngoc Dong, Ha Quang, 24.v.2022, found parasitizing a prepupa of S. javanum, Coll. P. H. Pham and Khuc Thi Ut.

REDESCRIPTION. Female ( Figs 8–14 ): Body length 1.1–1.2 mm, forewing length 0.8–1.0 mm.

Colour. Brownish black.Following parts yellowish:scape, pedicel, legs except coxae, sting. Ocelli and eyes red-brown.

Head ( Figs 8–9, 12–14 ). Semicircular in frontal view, about 1.1 times as wide as high; deeply vertical groove running around ocelli, then joining eye grooves from hind ocelli; facial grooves converging just below midocellus, then meeting at middle area of eyes as single carina elongating to scrobes; genal-clypeus margin near rounded; anterior margin of clypeus narrowly notched; mandible, about 1.4 times as wide as long, with three teeth on inner margin, first tooth small, long, very sharp, second well defined, third very broad, blunt; eyes with moderately dense, long setae; gena with moderately long setae; antenna covered with long setae, sparsely on scape and pedicel, densely on flagellum, with four articles, second article smallest, forth broadest with a club of three segments; placoid on all flagellomeres, two on first, one on second and third, and four on club; scape broad, conspicuously curved, 3.2 times as wide as long; pedicel longer than wide; length of antennal segments as follows: scape: pedicel: article 1: article 2: article 3: article 4 = 32: 12: 8: 5: 7: 18; maxillary palp about 2.7 times as wide as long.

Mesosoma ( Figs 10–14 ). Pronotum regularly sloped anteriorly, broader than high, about 1.7 time as long as wide, with broad rhombus on ventral surface; mesoscutum flat in profile view, with three lobes, length of posterior margin of mid lobe equivalent to that of anterior margin of mid lobe of scutellum; scutellum conspicuously convex, with mid lobe polish, about 1.9 times as wide as long and sublateral lobes with 3 long setae; propodeum polish, posterior margin small V-shaped at mid area, posterolateral angles obtuse. Forewing uniformly hyaline, 2.4 times as wide as long, with violaceous reflections and moderately dense, short pubescence; stigmal vein with uncus, length of stigmal vein equivalent to that of parastigmal vein; submarginal vein with 5 setae of equal length; marginal vein with a series of about 12–15 long setae, length of marginal vein 1.3 times that of submarginal vein and 6.1 times that of stigmal vein; length of submarginal vein 5.1 times that of stigmal vein.

Metasoma ( Figs 12–14 ). With six segments, 1, 2, and 3 of equal length; metasomal tergum 1 0.6 times as wide as long, width of metasomal tergum 1 0.8 times that of metasomal tergum 2; metasomal terga 2 and 3 equal in width; sting straight, rather long, length of sting about 0.5 times that of metasoma. Metasoma with rather dense long setae.

Male ( Figs 15–20 ): Body length 1.1–2.0 mm, forewing length 0.4–0.5 mm.

Colour. Golden brown, except flagellum blackish, mandible red brown.

Head ( Figs 15–17, 20 ). Broad, about 1.3 times as high as wide; eyes and ocelli reduce to small spots; vertex subcircular; genal-clypeal margin rounded; anterior margin of clypeus centrically, narrowly notched, with two laterally, long, small lobes; clypeus deeply impressed, a dense cluster of long setae immediately above impression; mandible 1.2 times as wide as long, with three teeth on inner margin, apical tooth long, broad, sharp, well separated from second, second and third teeth blunt, 2–4 setae sparsely distributed on outer surface; maxillary palp about 2.1 time as wide as long; antenna with five flagellomeres; article 1 smaller than 2 and 3; article 4 variably shaped and closely applied to segment 1 of club; apical flagellomere with a club of three segments; placoid on third segment of club; pedicel conspicuously concave on inner margin and much wider than flagella; scape, 1.9 times as wide as long, broom-shaped, curved, concave on outer margin; ventral surface with deep, broad, longitudinal groove, width of groove about 0.5 times that of scape; anterior margin of groove conspicuously wavy, with glandular area geniculate; posterior margin of groove straight; dorsal surface of scape with long setae; length of antennal segments as follows: scape: pedicel: article 1: article 2: article 3: article 4 = 26: 5: 2: 4: 3: 10. Head with rather long, white setae.

Mesosoma ( Figs 18–20 ). Pronotum sloped regularly anteriorly, 1.5 time as long as wide. Mesoscutum, scutellum, metascutellum polish; mesoscutum and propodeum with sparse setae. Scutellum without grooves, with 3 setae on each side. Fore leg: trochanter with stiff, short setae; tarsi with 2 segments; 1 as long as 2; 2, 3 and 4 fused. Mid leg: trochanter with curved, long setae; femur about 4.2 time as wide as long, with 18–20 setae on the ventral surface, 12 long setae on mid area; length to width of tibia 3.1: 1; tarsi with 3 segments. Fore wing long and narrow, about 4.1 time as wide as long, with its apex acute; marginal to submarginal vein length 1.6: 1.

Metasoma ( Figs 18, 20 ). With seven segments, length of metasomal tergum 1 0.8 times that of metasomal tergum 2, metasomal terga 2 and 3 in equal length. Metasoma with moderately dense, long setae.

DISTRIBUTION. Vietnam: Cao Bang, Ha Noi, Hoa Binh, Quang Ninh, Thai Binh, Thai Nguyen, Vinh Phuc (new records), Bac Ninh [ Pham et al., 2021]. Elsewhere: Japan, Taiwan [ Noyes, 2021].

Two externally morphological types of females are presented in M. sosui , long wing females as described above and short wing females that are similar to long wing females except their forewings reaching the middle area of the metasoma only. Dahms [1984] produced M. sosui as a new species based on comparisons of a few consistently different features between the species and M. assemi . He examined eight female wasp specimens of M. sosui and showed 2 setae on the left lobe and 3 setae on the right lobe of the scutellum. Possibly, this is a mistake feature observed by Dahms [1984], because more than 2500 specimens examined in the present study, we observed 3 setae on each lobe of the scutellum. On fresh specimens of M. sosui , wings were of violaceous reflections. This is not found in dry specimens in this study and is not stated in Dahms’ 1984 study. The body length of males markedly varies from 1.1 to 2.0 mm, but only 1.3 mm in Dahms’ 1984 study. Because of critical point dried specimens and limit of the number of specimens examined, several features of the species in comparison with M. assemi are omitted in Dahms [1984]. Hence, we, here, add some different features between them (Table 1).

HOST. Mathews et al. [2009] recorded seven cultural and natural hosts for M. sosui from Japan, Taiwan, and Netherlands, which were distributed in five families and two orders. González et al. [2018] recorded four cultural hosts for M. sosui from U.S.A., which were distributed in four families and two orders. Pham et al. [2021] recorded a natural host for the parasitoid from Vietnam. In the present study, we record- ed nine new natural hosts for M. sosui from Vietnam. Alto-

Table 1. Additional different features between M. assemi and M. sosui Таблица 1. Дополнительные отличиЯ между M. assemi и M. sosui Table 2. Hosts and countries recorded for the parasitoid M. sosui Таблица 2. ХоЗЯева и страны, отмеченные длЯ параЗитоида M. sosui

NOTES: * — cultural host, ** — country where M. sosui has been reared with cultural hosts.

ПРИМЕЧАНИЯ: * — культуральный хоЗЯин, ** — страна, где M. sosui выраЩивалсЯ на культуральных хоЗЯевах.

gether, 21 species of natural and cultural hosts are recorded for the parasitoid M. sosui (Table 2).

Acknowledgements. The authors are grateful to Dr. Jorge M. González, California State University, Fresno, California, USA for identification of the parasitoid M. sosui and to Mrs. Khuc Thi Ut for collecting specimens of M. sosui emerged from trap nests and from mud nests of other wasps. We sincerely thank reviewers for their valuable suggestions that helped us to improve this article. This research is funded by the Vietnam Academy of Sciences and Technology, project number CSCL09.01/23-24.

Competing interests. The authors declare no competing interests.

Figures

Figs 8–14. Melittobia sosui Dahms, female: 8 — head, frontal view; 9 — antenna; 10 — forewing; 11 — mesosoma, dorsal view; 12 — habitus and sting, lateral view; 13 — habitus, dorsal view; 14 — habitus, ventral view. Рис. 8–14. Melittobia sosui Dahms, самка: 8 — голова, вид спереди; 9 — антенна; 10 — переднее крыло; 11 — меЗосома, вид сверху; 12 — габитус и жало, вид сбоку; 13 — габитус, вид сверху; 14 — габитус, вид сниЗу.

Figs 15–20. Melittobia sosui Dahms, male: 15 — head, frontal view; 16 — mandible; 17 — antenna, ventral view; 18 — mesosoma and metasoma, dorsal view; 19 — mid leg; 20 — habitus, lateral view. Рис. 15–20. Melittobia sosui Dahms, самец: 15 — голова, вид спереди; 16 — нижнЯЯ челюсть; 17 — антенна, вид сниЗу; 18 — меЗосома и метасома, вид сверху; 19 — среднЯЯ ножка; 20 — габитус, вид сбоку.