Research Article |
Corresponding author: Kazunori Matsuo ( matsuosudachi@scs.kyushu-u.ac.jp ) Academic editor: Norman Johnson
© 2018 Kazunori Matsuo, Tomohisa Fujii, Makoto Tokuda, Tomoko Ganaha-Kikumura, Junichi Yukawa, Kenzou Yamagishi.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Matsuo K, Fujii T, Tokuda M, Ganaha-Kikumura T, Yukawa J, Yamagishi K (2018) Descriptions of two new species of Platygaster Latreille that attack gall midges (Diptera, Cecidomyiidae) with notes on their biology (Hymenoptera, Platygastridae). ZooKeys 754: 113-125. https://doi.org/10.3897/zookeys.754.23296
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Platygaster ingeniosus Matsuo & Yamagishi, sp. n. and P. urniphila Matsuo & Yamagishi, sp. n. (Hymenoptera: Platygastridae) are described from Japan. The former species is an egg-larval solitary parasitoid of Masakimyia pustulae Yukawa and Sunose (Diptera: Cecidomyiidae). The latter species is an egg-larval gregarious parasitoid of Rhopalomyia longitubifex (Shinji) (Diptera: Cecidomyiidae).
Platygaster ingeniosus , Platygaster urniphila , platygastrids, taxonomy
The genus Platygaster Latreille (Hymenoptera: Platygastridae) contains 601 species, of which approximately 300 species have been described from various biogeographic regions during the last two decades (e.g.,
Today, nine species of Platygaster are known to occur in Japan, of which seven parasitize gall midge species (Diptera: Cecidomyiidae) (
As demonstrated by
In order to contribute to further taxonomic and ecological studies of platygastrid parasitoids, we intend in this paper to identify the two undescribed species of Platygaster and to provide information on their host range and reproductive strategies.
Galls of Masakimyia pustulae and Rhopalomyia longitubifex were collected from Kyushu, Japan, in 2007–2017 to rear sufficient numbers of adults of Platygaster species for taxonomic study. In rearing Platygaster species that attacks Rhopalomyia longitubifex, the number of males and females emerged from one host larva were recorded to confirm its gregarious parasitism.
For morphological observation, adult parasitoids were preserved in 70–75% ethanol and subsequently dried from ethanol using the method described in
To compare morphological characters between known and the two Japanese species, we referred to original descriptions, redescriptions or keys for 512 (85.2%) out of 601 known species (Suppl. material
Holotypes and paratypes of the new species are deposited in the collection of the Biosystematics Laboratory, Faculty of Social and Cultural Studies, Kyushu University, Fukuoka, Japan.
Morphological comparison with some congeners revealed that the two unidentified species of Platygaster are distinct species and new to science. They are described below as P. ingeniosus and P. urniphila. The two new species share typical morphological characteristics of Platygaster and are distinctly different from the exceptional species mentioned in the Introduction.
The specific name is derived from its ingenious parasitoid strategy.
Type material. Holotype: Female, emerged on 16 March 2011 from a gall of Masakimyia pustulae on Euonymus japonicus collected by T. Fujii from Nijoshikaka, Itoshima, Fukuoka, Japan. Paratypes: 5 females and 5 males, same data as holotype.
FEMALE (Fig.
Head in dorsal view, 1.9–2.1 times as wide as long, 1.1–1.2 times as wide as mesosoma; occiput transversely striate; vertex between ocelli with transverse wrinkles, with reticulation between posterior ocelli (Fig.
Mesosoma 1.3–1.4 times as long as wide, 1.1–1.2 times as high as wide; sides of pronotum reticulate, smooth along upper and posterior margins (Fig.
Metasoma as long as head and mesosoma combined; T1 evenly crenulated, 1.8–1.9 times as wide as long, 0.2–0.3 times as long as T2; T2–T5 with a band of shallow punctation along posterior margin; T2 weakly striated in basal half, with shorter striae medially (Fig.
MALE. Differs from the female as follows: Body length 1.5–1.6 mm. Antenna with erect setae; A4 distinctly widened (Fig.
Platygaster ingeniosus is similar to the two Palearctic species, P. rutilipes Buhl and P. yunnanensis Buhl, because they share the following morphological characteristics: notaulus indicated in posterior half; mesopleuron with a coriaceous area below tegula; posterior margin of mesoscutum reaching base of mesoscutellum; hind wing approximately 4.8 times as long as wide. Platygaster ingeniosus can be distinguished from P. rutilipes by having the stouter fore wing that is 2.3–2.4 times as long as wide whereas P. rutilipes has elongated fore wing, approximately 2.8 times as long as wide. Platygaster ingeniosus could be distinguished from P. yunnanensis because sides of pronotum are finely reticulate whereas smooth in P. yunnanensis.
Platygaster ingeniosus is an egg-larval solitary parasitoid of Masakimyia pustulae in Japan (
The specific name, urniphila, is derived from the jar-shaped gall of Rhopalomyia longitubifex.
Holotype: Female, emerged on 2–4 April 2014 from a globular-jar shaped gall of Rhopalomyia longitubifex on Artemisia indica var. maximowiczii collected by K. Matsuo and Y. Matsuguma on 9 November 2013 from Chojabaru, Kokonoe, Oita, Japan. Paratypes: 1 female and 1 male, same data as holotype. 3 females, emerged on 31 March 2008 from a globular-jar shaped gall of Rhopalomyia longitubifex on Artemisia indica var. maximowiczii collected by K. Matsuo on 8 December 2007 from Jizoubaru, Kokonoe, Oita, Japan. 2 females, emerged on 8 April 2008 from a globular-jar shaped gall of Rhopalomyia longitubifex on Artemisia indica var. maximowiczii collected by K. Matsuo on 2 March 2008 from Chojabaru, Kokonoe, Oita, Japan. 2 females, emerged on 13 April 2008 from a globular-jar shaped gall of Rhopalomyia longitubifex on Artemisia indica var. maximowiczii collected by N. Wachi on 12 April 2008 from Kuju, Taketa, Oita, Japan. 5 males, emerged in April 2016 from a globular-jar shaped gall of Rhopalomyia longitubifex on Artemisia indica var. maximowiczii collected by K. Matsuo and Y. Matsuo on 24 March 2016 from Tano, Kokonoe, Oita, Japan.
FEMALE (Fig.
Head in dorsal view, 1.7–1.8 times as wide as long, 1.0–1.1 times as wide as mesosoma; occiput with weak transverse striations; vertex between ocelli smooth (Fig.
Mesosoma as high as wide, 1.3–1.4 times as long as wide; sides of pronotum broadly smooth which is sometimes with extremely fine striae, smooth along posterior margin (Fig.
Metasoma as long as head and mesosoma combined; T1 evenly crenulated, 1.7–1.8 times as wide as long, 0.2–0.3 times as long as T2; anterior margin of T2 weakly produced and overlapped T1; T2 weakly striated in basal half, with shorter striae medially (Fig.
MALE. Differs from the female as follows: Body length 1.1 mm. Antenna with erect setae; A4 distinctly widened; A5–A9 quadrate (Fig.
Platygaster urniphila can be distinguished from P. urnicola Yamagishi, a Japanese species, based on the following characteristics: mesopleuron with a few setae anteriorly (glabrous in P. urnicola); posterior margin of median lobe of mesoscutum not reaching base of mesoscutellum (reaching base of mesoscutellum in P. urnicola). Platygaster gifuensis was described based on a single male from Japan, from which P. urniphila can be distinguished by having A5–A9 quadrate (approximately 1.5 times as long as wide in P. gifuensis). Platygaster urniphila is quite similar to P. sublongicornis Buhl because they share the following morphological characteristics: vertex between ocelli smooth; frons smooth medially; mesopleuron with a few setae anteriorly, with a coriaceous area below tegula; mesoscutellum distinctly convex; T2 weakly striated in basal half, with shorter striae medially. However, Platygaster urniphila can be distinguished from P. sublongicornis based on the following characters: A4–A5 subquadrate (distinctly elongate in P. sublongicornis); OOL as long as LOL (1.6 times as long as LOL in P. sublongicornis); sides of pronotum smooth along posterior margin (smooth along anterior and posterior margins in P. sublongicornis); hind wing approximately 5.3 times as long as wide (4.5 times in P. sublongicornis).
Platygaster urniphila is an egg-larval gregarious parasitoid of Rhopalomyia longitubifex that induces axillary bud galls on Artemisia indica var. maximowiczii in Japan (
Reproduction by Platygaster urniphila: the number of adults emerged from a single larva of Rhopalomyia longitubifex.
Collecting date | Locality | Number of broods examined | Number of P. tubiphila emerged per larva (Mean ± SE) | ||
Female | Male | Total (Female + Male) | |||
8 December 2007 | Jizoubaru, Kokonoe, Oita, Japan | 1 | 29 | 0 | 29 |
2 March 2008 | Chojabaru, Kokonoe, Oita, Japan | 1 | 7 | 0 | 7 |
12 April 2008 | Kuju, Taketa, Oita, Japan | 1 | 8 | 0 | 8 |
9 November 2013 | Chojabaru, Kokonoe, Oita, Japan | 1 | 18 | 1 | 19 |
24 March 2016 | Tano, Kokonoe, Oita, Japan | 11 | 16.6 ± 1.4 | 2.7 ± 0.4 | 19.4 ± 1.6 |
18 March 2017 | Machida, Kokonoe, Oita, Japan | 23 | 11.4 ± 0.9 | 1.3 ± 0.3 | 12.7 ± 0.9 |
We wish to express our thanks to Dr E. Talamas for sending us high-resolution images of Platygaster gifuensis. We also thank Prof Y. Abe and Dr T. Ide for their support in taking SEM images, and Dr N. Wachi and Ms Y. Matsuo for their help in collecting galls of Rhopalomyia longitubifex. This study was supported partly by the Global COE Program (Center of excellence for Asian conservation ecology as a basis of human-nature mutualism), Ministry of Education, Culture, Sports, Science and Technology, Japan to KM and the Academic Challenge 2010 from Robert T. Huang Entrepreneurship Center of Kyushu University, Japan to TF.
A list of papers that were used for morphological comparison