A new species of Gryon Haliday (Hymenoptera: Platygastridae) from India

Acknowledgements: Authors are grateful to the Director, Zoological Survey of India (ZSI), Kolkata and the Officerin-Charge, ZSI, Calicut, for encouragement and facilities provided. The authors are extremely thankful to L. Masner for confirming the placement of this species in Leptocorisae species group. We also thank the Platygastroidea Planetary Biodiversity Inventory project for literature support. The genus Gryon (Hymenoptera: Platygastridae: Scelioninae) was erected by Haliday (1833), based on the type species Gryon misellum Haliday. The genus is cosmopolitan and highly diverse. A total of 57 species are known from the Oriental region (Johnson 1992; Ohio State University 2013), of which 17 species have been recorded from India (Mineo 1991; Mineo & Caleca 1994; Rajmohana 2011). The species of this genus generally attack eggs of Hemiptera belonging to Coreidae, Pentatomidae, Scutelleridae, Lygaeidae, Reduviidae, Phymatidae (Rajmohana et al. 2011). This genus can be easily distinguished from the rest of the scelionines by the presence of an unarmed metascutellum and propodeum, absence of skaphion, short and plump; and transverse terminal metasomal segment which is not wedge-shaped (Masner 1976; Rajmohana 2013). In this paper a new species, Gryon ambericum sp. nov., is described and illustrated.

This genus can be easily distinguished from the rest of the scelionines by the presence of an unarmed metascutellum and propodeum, absence of skaphion, short and plump; and transverse terminal metasomal segment which is not wedge-shaped (Masner 1976;Rajmohana 2013). In this paper a new species, Gryon ambericum sp. nov., is described and illustrated.

Material and Methods
This study is based on specimens collected from a paddy ecosystem as well as from the wild, by the authors. The specimens were studied under a Leica M 205A stereomicroscope. Images were taken with a digital camera Leica DFC 500 and processed using extended focus LAS montage software. The types are deposited at the Western Ghats Regional Centre, Zoological Survey of India, Kozhikode, Kerala (ZSI, WGRC). Morphological terminology follows Masner (1980) and Miko et al. (2007).
Etymology: The species name ambericum based on the amber (= yellowish-brown) colour of the mesosoma and metasoma.

Discussion
The new species, Gryon ambericum sp. nov., belongs to the leptocorisae species-group of Gryon. As defined by Mineo (1990), members of this group share the following characters: slender clava; incomplete occipital carina, almost surpassing the foramen magnum and without the horizontal branch; epomia strongly reduced; clypeus with anterolateral corners almost acute; M about as long as STG and an elongate PM (more than twice STG).
In the key to the Indian species given by Sharma (1982), G. ambericum runs out at couplet number 2, and as no recent keys are available to the Oriental species or Indian region, this new species is compared with the descriptions of all species of Gryon so far reported from India and the Oriental region. The following unique characters serve as diagnostic characters of this species: a unique dorsally quadrate (Image 2), laterally subtriangular black coloured head and a quite contrasting amber coloured mesosoma; head width only 1.2x head length; frontal depression deep, not margined by a carina (Image 4); eyes without pilosity; mandibles bidentate; metasoma unusually elongate, more than 2x as long as wide, unlike the short and plumpy stature commonly met with in the genus; and T2 largest of all tergites, 2.6× longer than T1 and 3× longer than T3.
All Gryon species known so far from India have a much wider head, with dorsal width to length ratio usually equal to or greater than two and metasoma length to width ratio has never exceeded 1.5× and hence cannot be confused with G. ambericum sp. nov.
Three Vietnamese species of Gryon (Lê 2000) show a slight resemblance to G. ambericum sp. nov. as regards the shape of head and metasoma. However, G. ambericum can be distinguished from G. longus Kozlov et Lê, G. varius Kozlov et Lê and G. narus Kozlov et Lê by the following characters: (i) In G. ambericum sp. nov., head width is 1.3× its length and metasoma length 2.3× its width (in G. longus head width is 1.5× its length, metasoma length 1.5× its width), and (ii) In G. ambericum sp. nov., scape length is 6.3× length of radicle, forewing length is 3.95× its width and PM 3.1× STG (in G. varius scape length is 5× that of radicle, forewing length 2.5× its width, PM 2.5× STG whereas in G. narus scape length is only 4.2× that of radicle; forewing length is only 2.8× its width).