The genus Dendrocerus Ratzeburg, 1852 (Hymenoptera: Megaspilidae) was described with Dendrocerus lichtensteinii Ratzeburg as the type species (by monotypy), a synonym of Ceraphron halidayi Curtis, 1829. This was later designated as a type of Lygocerus, a genus proposed as new by Förster (1856). But Dessart (1966) synonymised Lygocerus with Dendrocerus, and D. lichtensteinii with C. halidayi and the generic transfer of the latter with D. halidayi. Dessart (1995) proposed a division of the species (especially males), based on some antennal characters, into five species-groups like halidayi, carpenteri, serricornis, punctipes and penmaricus.
The species of the genus Dendrocerus are either primary parasitoids of Neuroptera and Diptera or hyperparasites upon Homoptera and Coleoptera through Hymenoptera (Takada 1973). It is cosmopolitan in distribution with 118 world species. But only 15 species are known from the oriental region so far (Johnson & Musetti 2004). The Indian fauna is represented by six species (Rondani 1877; Mani 1939; Dessart 1973, 1999; Sharma 1983) of which one species, D. mucronifer Dessart belongs to the D. halidayi group. The males of the D. halidayi species group are characterised by their ramose antennae, and by the long branches on proximal 4, 5 or 6 flagellomeres. There are 22 species of this group worldwide (Pezzini et al. 2014).
In continuation with our pioneering taxonomic studies on the superfamily Ceraphronoidea of India, a new species under Dendrocerus halidayi group, viz., D. istvani is hereby described and illustrated. A key to distinguish the Oriental species of the D. halidayi group is also provided.
Materials and Methods
The specimens under study were collected using a sweep net. They were mounted on point-cards. Photographs were taken with a Leica M205A stereomicroscope, with 1x objective and Leica DFC-500 digital camera, with extended focusing software. Morphological terminology follows Fergusson (1980), Dessart (1999) and Miko & Deans (2009). Measurements are given in microns. Slide of male genitalia was prepared using the method given by Polaszek & Kimani (1990). Genitalia terminology follows Hymenoptera Anatomy Consortium (2014). The preparation was examined and photographed using Leica DM 2000 compound microscope with Leica DFC-500 digital camera.
The types are deposited in the National Zoological Collection, Western Ghat Regional Centre, Zoological Survey of India, Kozhikode.
Dendrocerus istvani sp. nov.
Holotype: ZSI/WGRC/IR/INV. 2975, 13.ix.2008, Male, Kaddu Khal, Tehri District, Uttarakhand, India, 30024’27.28”N & 78017’18.16”E, elevation 2,529m (field dominated with tree species like Quercus dilatata, Cedrus deodera and Rhododendron arboretum), collected in a sweep net, coll. Dr. Sudhir Singh.
Paratypes: ZSI/WGRC/IR/INV. 2976 and 2977, two males, with same data as that of the holotype.
Male antennae ramose with six long and slender branches; ra1 1.5x times as long as scape; ra6 longer than the following segment A9 and its axial body A8; A8 with a small spur; A9 longer than the A8; head transverse; DFIm 53% of the total head width; ocellar triangle isosceles and broad based; POL more than twice the length of LOL; fore wing hyaline; radius and stigma subequal in length; metasoma compressed (width/height = 0.60) with clear notaulices which is diverging and parallel to median groove; apex of the scutellum without mucron; large metasomal tergite with fine punctuation in posterior half dorsally; volsella with five and four solid setae on right and left parossiculi.
Coloration: Black body with darker head and mesosoma; eyes silvery with a bronze tinge; ocelli brownish yellow; scape and hind coxa black with brownish yellow basal area in former; pedicel brownish-yellow; A3 and following segments chocolate brown; fore and mid coxa along with femur and tibia chocolate brown with brownish-yellow joints; large metasomal tergite, T3, chocolate brown (Image 1); pterostigma and costal vein brown; radial vein pale brown (Image 7); body pubescence white; marginal fringes of wings brown.
Body: length: 2.25mm.
Head: Head width 2.28x head length (length/width/height = 252/576/660); eye: eyes 1.2x longer than wide (length/width = 290/238); transverse in dorsal view, preoccipital crescent well marked, separated from hind ocelli and merging laterally into eye margin (Image 6); temple strongly carinated; preoccipital furrow present; ocellar triangle isosceles, short, broad and elevated; posterior ocelli separated from anterior ocellus by a distance of a little more than 2x post ocellar length; hind ocelli remote from eye margin; depressions near lateral ocelli shallow and that in front of median ocellus (supraoccipital groove) deep and conspicuous; POL/LOL/OOL: (111/52/62) (Image 5). DFIm 53% of head width; facial sulcus absent (Image 2); lower frons with strip of irregular transverse scattered striae denser more towards lateral ocular suture interspersed with fine granulate sculpture; supraclypeal depression absent; intertorular carina distinct (Image 2); ocular suture prominent and foveolate; eyes pubescent (Image 2); frons with sparse hairs; densely pubescent at gena.
Antenna: (Image 4). Ramose with six branches; pubescence more than two times longer than width of branches; scape nearly four times longer than wide; pedicel small and almost globular; ra1 1.5x times longer than scape; ra6 distinctly longer than its axial body (A8) and immediate segment following (A9); A8 proximally narrow and distally wide, with a small indistinct spur apically; branches decreasing their width from ra1 to ra6 respectively; ra3 being longest branch (1.75x scape length); length/width measurements of antennal segments: scape (378/81), pedicel (64/59), A3 (60), ra1 (580), A4 (95), ra2 (640), A5 (114), ra3 (660), A6 (134), ra4 (630), A7 (203), ra5 (540), A8 (258), ra6 (360), A9 (268/52), A10 (176/63), A11 (198/53).
Mesosoma: (Image 6). Mesosoma fairly narrow (1.7x longer than wide) (Length/width/height = 1016/606/660); coriaceous in sculpture, densely pubescent; mesoscutum: (Length/width = 437/568); mesoscutum 1.3x wider than long, with more or less straight anterior margin; anterior corners of mesoscutum sharply angled; mesoscutal humeral sulcus evident; coarsely foveolate notaulices angled sharply, running parallel to median furrow and meeting at transscutal articulation (Image 6); scutellum 1.5x longer than wide, narrowed at apex with densely setose lateral margin; lateral scutellar carina evident; scutellum convex and highly sculptured with numerous hairs; metanotum and propodeum carinated; anterior margin of propodeum with a median spur.
Wing: (Image 7). Total wing length 1.94mm. Hyaline. Pterostigma (Length/width = 352/137) elliptical, 2.6x longer than wide; distal edge of pterostigma truncated; Radius (367mm), curved a little in the middle and nearly subequal (1.04x) to pterostigma; wing densely pubescent and marginal fringes numerous; hindwing without venation.
Metasoma: (Image 3) Mesosoma 1.7x longer than wide (Length/width/height = 962/503/507); metasoma smooth, but with numerous pit like punctuations in posterior one fourth of largest tergite, T3; eight strong transverse gastral carinae present in basal portion of metasoma; gastrocoeli not evident; T3 occupying 67% of metasomal length; five terminal segments visible dorsally with numerous hairs; genitalia with short basal ring, volsella with five prominent lateral setae on each left parossiculi and four on each right parossiculi (Image 8); harpe with numerous terminal long and slender setae.
The species is named ‘istvani’; in honour of Dr. Istvan Miko, for his tremendous support and encouragement throughout our studies.
The new species is morphologically similar to the African species, D. incertissimus Dessart, 1999, in the antennal features - long slender six branches, ra1 longer than scape, A8 with a spur and with scutellar carina, but differs mainly in ocellar triangle ratio. D. istvani sp. nov. has its OOL greater than LOL, but in D. incertissimus it is just the opposite. Forewing of D. istvani sp. nov. is hyaline, while in D. incertissimus it is infuscate under radius; ra2 6.7x as long as its axial body (A4) in D. istvani sp. nov., while in D. incertissimus it is 8.6x as long as its axial body. A9 is longer than A8 in the new species, but it is reverse in D. incertissimus.
Both the species being high altitude species they share a degree of relatedness in their ecology. D. istvani sp. nov. can be distinguished from the Indian species, D. mucronifer and other Oriental species as per the key given.
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