Description of Aphelopus fuscoflavus , a new species of Dryinidae from Thailand ( Hymenoptera , Chrysidoidea )

A new species of Aphelopus Dalman is described from Thailand, Sakon Nakhon: A. fuscoflavus sp. n. Morphologically the new species is similar to A. zonalis Xu, Olmi & He, 2013, known from China, Hainan, but it is clearly different in having the basivolsella fused with the paramere, while the basivolsella is not fused with the paramere in A. zonalis. Published identification keys to the Oriental species of Aphelopus are modified to include the new species.

Aphelopus species are parasitoids of leafhoppers belonging to Typhlocybinae (Cicadellidae) (Guglielmino et al. 2013).Contrarily to almost all dryinids, females of Aphelopus do not have chelae and do not feed on their hosts; they grasp the body of their hosts between the two fore legs, with or without the help of their mandibles (Olmi 1984(Olmi , 1994)).
In 2016 we examined additional specimens of Aphelopus from Thailand and discovered a new species described in this paper.

Materials and methods
The descriptions follow the terminology used by Olmi (1984) and Xu et al. (2013).The measurements reported are relative, except for the total length (head to abdominal tip, without the antennae), which is expressed in millimetres.The following abbreviations are used in the descriptions: POL is the distance between the inner edges of the two lateral ocelli; OL is the distance between the inner edges of a lateral ocellus and the median ocellus; OOL is the distance from the outer edge of a lateral ocellus to the compound eye; OPL is the distance from the posterior edge of a lateral ocellus to the occipital carina; TL is the distance from the posterior edge of an eye to the occipital carina.
The types of all Oriental species of Aphelopus have been previously examined by the authors.
The type specimen described in this paper is deposited in the collection of the Queen Sirikit Botanic Garden, Chiang Mai, Thailand (QSBG).
Etymology.The name fuscoflavus derives from the Latin adjectives "fuscus" (dark) and "flavus" (yellow), because of the partly testaceous and partly brown colour.
Remarks.Because of the head testaceous, except large brown spot on vertex, the mesosoma partly testaceous and partly brown, the complete notauli, the basivolsella with one subdistal bristle, the new species is similar to Aphelopus zonalis Xu, Olmi & He, 2013, described from China, Hainan.The main difference between A. fuscoflavus and A. zonalis is centered on the structure of the basivolsella; fused with the paramere (Fig. 2) in A. fuscoflavus, not fused in A. zonalis (Fig. 3).In the key to the males of the Oriental Aphelopus species published by Xu et al. (2013), the new species can be included by replacing couplets 1-4 as follows:  In comparison with the 193 species recorded in China by He and Xu (2002) and the 62 and 40 listed respectively in India and Laos (Xu et al. 2013), the dryinid fauna of Thailand is poorly known.Some genera such as Gonatopus (with only seven species listed) are clearly understudied.
However, the dryinids of Thailand will be better understood in the future.In fact, during the three year period 2006-2009, an intensive survey of the terrestrial arthropod fauna of Thailand was conducted by the Queen Sirikit Botanic Garden, The Thai Forestry Group, The Hymenoptera Institute and The Natural History Museum of Los Angeles County (TIGER: Thailand Inventory Group for Entomological Research, coordinated by Michael Sharkey) (http://sharkeylab.org/tiger/).This survey resulted in the collection of about 5000 specimens of Dryinidae, which are actually in study in the authors' laboratories.The new species described herein is one of the first results of this study.