First report of the genus Conostigmus Dahlbom (Hymenoptera: Ceraphronoidea: Megaspilidae) from India with description of a new species

Abstract The genus Conostigmus Dahlbom (Hymenoptera: Ceraphronoidea: Megaspilidae) is reported for the first time from India, along with description and illustration of Conostigmus neotubifer sp. n. A comparative discussion on the morphological affinities of the new species with its putative sister Conostigmus tubifer Dessart is provided. An intermixing of character states of genera Conostigmus as well as Dendrocerus Ratzeburg is observed.

Among the 13 genera of Megaspilidae, the most speciose and widely distributed are Dendrocerus Ratzeburg 1852 and Conostigmus Dahlbom 1858. The genus Conostigmus was erected by Dahlbom (1858), as a subgenus of Megaspilus Westwood, with Megaspilus alutaceus Thomson as type species. Later in 1951, Muesebeck and Walkley elevated the taxon to generic level. The genus is distributed widely in all geographical realms and has 168 species. Only 9 species have been reported from Oriental region so far (Johnson andMusetti 2004, Dessart 1997) (catalogued as 8 species by Johnson and Musetti (2004), missing out C. occipitalis Dessart 1997).
In continuation with our pioneer taxonomic studies on the superfamily Ceraphronoidea of India, a new species of Conostigmus viz. C. neotubifer sp. n. is hereby described and illustrated. A comparative discussion on the morphological affinities of the new species with C. tubifer Dessart 1997, the most resembling species is also provided. Both the species are remarkable for their intermixing of characters seen in two genera, Conostigmus and Dendrocerus.

Materials and methods
The specimens under study were collected using malaise trap set among the grassy patches of Port Blair, Andaman and Nicobar Islands, India. The specimens were card mounted on point-card tips. Description and imaging works were carried out employing Leica M205A stereomicroscope, with 1 × objective and Leica DFC-500 digital camera. Morphological terminology follows Fergusson (1980), Dessart (1997) and Miko and Deans (2009). Based on Dessart (1997), we have attempted to define the various states of ocellar triangle in Megaspilidae. If OOL > POL, the ocellar triangle is 'narrow-based' and if OOL POL.
Both the Holotype and the Paratypes are deposited in the National Zoological Collection at Zoological Survey of India, Calicut.
Coloration: Body blackish brown with head more darker; eyes and ocelli silvery with a bronze tinge; fore wing clear at base, with large infuscate area below pterostigma and radial vein extending to its posterior margin; scape, pedicel and A3 brownish yellow turning darker towards segments from A4 onwards; legs brownish yellow with coxae and posterior half of hind tibia blackish brown (Fig. 1); mandible light brown with darker distal extreme; pterostigma brown getting darker to wing margin; radial vein and costal vein pale brown (Fig. 8); body pubescence white.
First report of the genus Conostigmus Dahlbom (Hymenoptera: Ceraphronoidea: ...   Body length 1.68 mm. Body colouration and the morphological features of head, mesosoma and metasoma are the same as holotype, except the measurements of antennal segments, proportion of radius and pterostigma and length of metasoma.
Scape more than 4 × as long as wide and A3 more than 3 × as long as wide. Pedicel slender to succeeding antennal segments. Length/width measurements of antennal segments: scape (   Male genitalia ventral view.
DFIm 52% of head width and fore wing infuscation much darker compared to paler infuscation in male fore wing. T3 occupying 57% of metasomal length.

Diagnosis
Conostigmus neotubifer sp. n. can be diagnosed by the following features.
Head transverse, wider than mesosoma. Male antenna subequal to body length with A3 highly slender, 4.8 × as long as wide and subequal to scape. Flagellar segments in male quasi cylindrical with very slight serrations basally. Female antenna with scape more than 4 × as long as wide and A3 more than 3 × as long as wide. Ocellar triangle isosceles, narrow based, short and raised in both sexes. Facial sulcus extending to intertorular carina in both sexes. Preoccipital furrow distinct. Supraclypeal furrow absent. DFIm 0.57% of head width in male and 0.52% of head width in female. Eyes densely pubescent. Dorsal margin of propodeal foramen 'U' shaped in dorsal view; median propodeal projection absent. Sternaulus absent. Metasoma dorsally elevated from the propodeal axis. Forewing infuscus, darker in female and paler in male.

Distribution
INDIA, Andaman Nicobar island, Port Blair.

Biology
Unknown.

Discussion
The proposed new species is placed under Conostigmus, since its putative sister C. tubifer belongs also to Conostigmus and can be justified mainly by the presence of independent parossiculi in male genitalia, one of the diagnostic characters for the subgenus Conostigmus s.str. in Dessart and Cancemi (1989). C. tubifer is unique among the Oriental species because of its affinity to Dendrocerus due to the quasi cylindrical appearance of male antennal segments, broad based nature of ocellar triangle (Dessart 1997), along with characters as mentioned (Table 1). Except in the ocellar ratio C. neotubifer resembles C. tubifer, in aspects regarding head, mesosoma and metasoma (Table 1) and also in having an upwardly elevated posture of metasoma. This intermixing of character states of the two genera Conostigmus and Dendrocerus in C. tubifer and C. neotubifer sp. n. emphasizes the uncertain state of the current classification of Ceraphronoidea. In C. neotubifer sp. n., OOL > POL (ocellar triangle is narrow based), while in C. tubifer OOL C. tubifer in Dessart (1997), regarding ocelli, is a mismatch. In the description of the holotype male, Dessart clearly states, supported by numerical values, that the ocellar triangle is broad based, which is in contradiction to the medial placement of ocellar triangle in the illustration. As the holotype of C. tubifer could not be traced, we had no means than to go by the descriptive part of the original literature, since it is supported by numerical values. Though NHM is mentioned as the type depository of C. tubifer, in Johnson and Musetti (2004) and Dessart (1997), on enquiry at NHM, we were informed that the types were never deposited there in reality.
In addition, the differences in the following characters also ensure that tubifer and neotubifer are not conspecific.