Parasitoids of the genus Pholetesor Mason, 1981 (Hymenoptera: Braconidae: Microgastrinae) from the leafminers Lepidoptera, with the description of three new species from India

Pholetesor acrocercophagus sp. nov., P. camerariae sp. nov. and P. indicus sp. nov. (Hymenoptera: Braconidae: Microgastrinae) are described as new to science. These three species were reared from Acrocercops sp., Acrocercops phaeospora Meyrick, 1916 and Cameraria virgulata Meyrick, 1914 (Lepidoptera: Gracillariidae), respectively. Characteristics of these new species and their affi nities with related taxa are discussed. Data on habitat, host records and host plant species for all the parasitoid species is provided. A key to the Indian species of the genus Pholetesor Mason, 1981 reared from lepidopteran leafminers is also given.


Introduction
Leaf-mining insects are considered serious pests which damage plant leaves in a variety of ways. If leaves are seriously attacked, crop can be reduced or seedling plants may be totally destroyed (Spencer 1990). The majority of the leaf-mining larvae belong to the Lepidoptera Linnaeus, 1758, followed to a lesser degree by Diptera Linnaeus, 1758, Coleoptera Linnaeus, 1758 and Hymenoptera Linnaeus, 1758 (Csoka 2003). Among the lepidopteran leafminers, the family Gracillariidae Stainton, 1854 includes small-sized moths with white marks on the wings. Several species are considered serious pests in several parts of the world (Davis 1987). Parasitoid insects play the most important role as natural enemies of leafminers, because in some cases, they can cause more than 90% mortality and consequently have great potential in biological pest control programs (Hawkins et al. 1993). Parasitoids of leafminers are exclusively from the order Hymenoptera, with superfamilies Chalcidoidea Latreille, 1817, Ichneumonidae Latreille, 1802 and Braconidae Burmeister, 1829 being the most important groups associated with leafminers. Mason (1981) erected the genus Pholetesor Mason, 1981 to accommodate Nixon's (1965) ʻcircumscriptus-groupʼ and ʻbucculatricis-groupʼ of species of Microgastrinae Förster, 1862. This genus has 57 species recorded from the world, but only one species, P. hayati Akhtar & Ahmad, 2010, has been reported from India (Akhtar et al. 2010;Yu et al. 2016;Fernandez-Triana et al. 2020). Known hosts of various species of Pholetesor are almost exclusively leaf-mining Lepidoptera (Whitfield 2006). Pholetesor is characterized by the following characters: 1) short and hairy and relatively dorsally attached ovipositor sheaths; 2) strong sub-lateral setiferous lobes of the metanotum; 3) propodeal areola (when present) strongly pentagonal rather than oval or diamond-shaped (Whitfield 2006); 4) hypopygium medially folded but evenly sclerotized or only weakly translucent medially; 5) 2r-m of fore wing absent.
As far as India is concerned, there is a lack of information on braconid parasitoids, especially reared from leaf-mining lepidopteran hosts. There were only four microgastrine parasitoid wasps described from India (Wilkinson 1928;Ahmad et al. 2019). In the present, work three new parasitoid species, viz, Pholetesor acrocercophagus sp. nov., P. camerariae sp. nov. and P. indicus sp. nov. reared from Acrocercops sp., Acrocercops phaeospora Meyrick, 1916 andCameraria virgulata Meyrick, 1914 (Lepidoptera: Gracillariidae), respectively, are described and illustrated, and their affinities with related taxa are discussed. A key to the Indian species of the genus Pholetesor reared from lepidopteran leafminers is provided. This work was initially started in 2004 by first author ZA during his post-doctoral project on rearing braconid parasitoids from India. A part of this work is included in the PhD thesis of the third author KP (Pandey 2006).

Material and methods
This study was conducted in the vicinity of western Uttar Pradesh (North India) in order to identify the parasitoids of leafminers along the roadside at AMU university campus. The parasitoids were reared from Acrocercops sp., A. phaeospora and C. virgulata on the tree leaves of Achyranthes aspera L., Millettia pinnata (L.) Panigrahi and Syzygium cuminii (L.) Skeels, respectively, in the laboratory in glass jars. A complete data set such as the date of collection, locality and name of host plant was maintained. The emerged parasitoids were initially preserved in 75% alcohol with a few drops of glycerol. These specimens were later mounted on cards. The reared parasitoids were separated based on morphological characters. The Pholetesor species keys of Nixon (1973), Papp (1983) and Liu et al. (2016) were used for the identification. Van Achterberg (1993) is followed for the terminologies of various body parts and wing venation and Eady (1968) for the terminology of micro-sculpture. The types of new species were deposited in the Insect Collection of the Department of Zoology, Aligarh Muslim University, Aligarh, India (ZDAMU).

Abbreviations for morphological terms used in the text
AOL = anterior ocellar line (distance between the inner edges of an anterior ocellus and lateral ocellus) POL = posterior ocellar line (distance between the inner edges of lateral ocelli) OOL = ocello-ocular line (distance from the outer edge of a lateral ocellus to the compound eye) OD = ocellus diameter F = flagellomere T = metasomal tergite

Diagnosis
Pholetesor acrocercophagus sp. nov. is closely related to P. circumscriptus (Ness, 1834) in the European keys to the species of the ʻcircumscriptus-groupʼ (Nixon 1973;Papp 1983) on the basis of the following characters: thorax in profile less elongate; metanotum strongly retracted from scutellum anteriorly, exposing mesothoracic postphragma; pterostigma almost 3.0 × as wide as long; vein 1-R1 (metacarp) clearly longer than pterostigma, r and 2-SR slightly curved, meeting less angularly; propodeum largely smooth; hind femur yellowish; T1 largely smooth, polished and strongly narrowed apically; T2 + 3 smooth and polished. However, it differs from P. circumscriptus in the following characters: T2 subtriangular 2.0 × as wide as long posteriorly, hence more transverse (T2 strongly triangular 2.6 × as wide as long posteriorly in P. circumscriptus); scutellar sulcus narrow with fine foveation (scutellar sulcus narrow with fine groove in which there is no obvious foveation in P. circumscriptus); forewing vein r arising medially of the pterostigma (forewing vein r arising distally of the pterostigma in P. circumscriptus); F2 2.5 × as long as wide (F2 3.6 × as long as wide in P. circumscriptus); body comparatively small, about 1.5 mm (body larger, about 1.80-2.00 mm in P. circumscriptus).

Etymology
The new species is named after its host insect.

Description Female
MeasureMents. Body lenght = 1.5 mm; Length of fore wing = 1.6 mm; Length of antenna = 1.5 mm. Head. Almost 2 × as wide as long; eyes 1.6 × as long as temple in dorsal view; temple and vertex smooth, shiny, punctate with hairs; eyes setose, 1.4 × as long as wide, OOL: POL: AOL: OD = 4: 3: 2: 2; frons concave, smooth and shiny, face medially convex, punctate with hairs; clypeus 3 × as wide as long, flattened, indistinctly punctate; malar space about as long as basal width of mandible; antennae about as long as body; scape 1.5 × as long as wide, pedicel slightly wider than long, F1 3.0 × as long as wide, F2 2.5 × as long as wide, flagellomeres gradually decreasing apically, apical flagellomere longer than F15 and pointed.
MesosoMa. About as long as wide and 1.5 × its height; mesoscutum distinctly punctate with hairs, punctations becomes obscured posteriorly, scutellar sulcus narrow with fine foveation; scutellum smooth and shiny, side of scutellum smooth and shiny; propodeum about 2.0 × as wide as long at longest point, largely smooth; posteriorly with series of ridges extending obliquely on either side from nucha; propleuron smooth and shiny; mesopleuron antero-dorsally smooth and shiny, postero-laterally punctate with hairs.

Male
Unknown.

Remarks
Pholetesor acrocercophagus sp. nov. can be distinguished from all previously described species by the unique combination of characters as follows: metanotum strongly retracted from scutellum anteriorly, exposing mesothoracic postphragma; propodeum about 2.0 × as wide as long at longest point, largely smooth; posteriorly with a series of ridges extending obliquely on either side from nucha; T1 about 3.0 × as long as its apical width, 1.8 × its basal width, strongly narrowed apically, smooth and shiny except few punctures; T2 2.0 × as wide as long, subtriangular, smooth, shiny, shorter than T3; T3 rectangular, 1.40 × as long as T2, unsculptured; hypopygium weakly sclerotized, transparent, medially folded, blunt at apex, 2.0 × as long as hind basitarsus; ovipositor sheaths elongate-fusiform, thick and hairy throughout their length, arising about half of valvifer; ovipositor pointed at apex and curved downwards.
Pholetesor camerariae sp. nov. is also closely related with P. salalicus (Mason, 1959) in the key to the Chinese species of the genus Pholetesor (Liu et al. 2016). However, it differs from P. salalicus in the following characters: T2 smooth except few hairs, trapezoidal, 1.5 × as wide as long, (T2 rugose, subtriangular to trapezoidal, 1.7-2.0 × as wide as long in P. salalicus); posterior margin of T2 usually weakly concave (posterior margin of T2 straight in P. salalicus); propodeum about 2 × as wide as long, shallowly rugulose to rugose, smooth at antero-lateral corners (propodeum about 1.7 × as wide as long at longest point, punctate to weakly rugulose antero-laterally, smooth and depressed in postero-lateral corners).

Etymology
The new species is named after its host insect. Head. Almost 2 × as wide as long in dorsal view; eyes as long as 2.0 × as temple in dorsal view; OOL: POL: AOL: OD = 4: 3: 2: 2; temple smooth, shiny, punctate with hairs; vertex convex, smooth, shiny, indistinctly punctate with hairs; frons concave, smooth and shiny; face 1.3 × as wide as long, medially convex, punctate with hairs; clypeus convex, punctate with hairs; malar space about as long as basal width of mandible; antennae longer than body length, apical four flagellomeres without double rank of placodes, F1-F7 equal in length, F8-F15 gradually decreasing in length apically, apical flagellomere slightly longer than F15.

Holotype
MesosoMa. 1.3 × as long as wide dorsally and just above the tegulae as wide as head; scutum shallowly punctate with hairs, becoming nearly impunctate at extreme posterior edge; scutellar sulcus almost straight and foveolate to crenulated; scutellum smooth with fine, shallow punctures; metanotum weakly retracted from scutellum; sublateral setiferous lobes nearly appressed to hind margin of scutellum; transverse carinae poorly developed; propodeum about 2 × as wide as long, shallowly rugulose, smooth at antero-lateral corners, with pair of ridges extending obliquely on either side from nucha; propleuron smooth and shiny; mesopleuron mostly smooth except few hairs anteriorly; metapleuron smooth and shiny except edges.
Wings. Fore wing 2.5 × as long as wide; 1-R1 about as long as pterostigma; r slightly longer than 2-SR; r and 2-SR meeting angularly. Hind wing with Cu-a declivous; venal lobe evenly convex and hairy; pterostigma almost 3 × as long as wide. Legs. Hind coxa smooth and shiny, almost reaching posterior end of T3; length of femur, tibia, and basitarsus of hind leg 4.0, 6.0 and 6 × their width, respectively, longer tibial spur 0.41 × as long as basitarsus (12:5).

Male
Same as holotype.

Remarks
The new species bears strong resemblance to another Indian species, P. hayati, in the colouration of the tegulae, wing veins, stigma and legs (except hind coxae), and the sculpturing of the propodeum and metasomal tergites (but not their exact shapes -P. hayati has a broader first tergite with rounded lateral margins and a somewhat longer second tergite). Also showing some resemblance in the Palearctic fauna is P. laetus (Marshall, 1885) and P. salalicus, both of which shares a number of colour and tergite features with P. camerariae sp. nov., but both the Palearctic species have more sculptured T2 than P. camerariae sp. nov., and scutellar sulcus reduced to a fine groove in which there is no obvious foveation, while P. camerariae sp. nov. has a distinct faveolated groove in scutellar sulcus.
The new species is also very similar to P. circumscriptus. However, it differs from P. circumscriptus in the following characters: vein 1-R1 (metacarp) as long as or shorter than pterostigma (vein 1-R1 (metacarp) clearly longer than pterostigma in P. circumscriptus); T2 subtriangular, 2.0 × as wide as long posteriorly, hence more transverse (T2 strongly triangular, 3 × as wide as long posteriorly in P. circumscriptus); forewing vein r and 2-SR meeting angularly (forewing vein r and 2-SR meeting each other less angularly in P. circumscriptus).
Apart from the similarities with P. bicolor, the new species also runs close to P. teresitergum Liu & Chen, 2016 in the key to the Chinese species of the genus Pholetesor (Liu et al. 2016). However, it differs from P. teresitergum in the following characters: eyes 2.2 × as long as temple in dorsal view (eyes 1.6 × as long as temple in dorsal view in P. teresitergum); ocelli large (ocelli relatively small in P. teresitergum); scutellum highly polished (scutellum punctate with hairs in P. teresitergum); ovipositor sheaths small and thick, slender with a bluntly rounded tips, (ovipositor sheaths small and subfusiform in P. teresitergum); tegulae blackish brown (tegulae yellowish in P. teresitergum). Paratypes INDIA • 5 ♀♀, 2 ♂♂; same collection data as for holotype; ZDAMU.

Etymology
The new species is named after its type locality.
MesosoMa. 1.5 × as long as wide; mesoscutum as wide as head and strongly punctate with hairs, punctations prominent all along mesoscutum surface; scutellar sulcus narrow and crenulate; scutellum smooth and polished, side of scutellum smooth and shiny; propodeum almost 2 × as wide as long, largely smooth except antero-medially punctate with long hairs, posterior corners somewhat weakly rugulose; propleuron smooth and shiny; mesopleuron concave, smooth and shiny, antero-lateral, punctate with hairs; metapleuron smooth and shiny with few hairs.
Wings. Fore wings hyaline, about 3.0 × as long as wide, pterostigma about 3.0 × as wide as long, 1-R1, about 0.9 × as long as length of pterostigma, r and 2-SR meeting angularly; venal lobe of hind wing convex.
MetasoMa. 1.7 × as long as wide; T1 3.6 × as long as its apical width and 1.8 × its basal width, distinctly narrowed apically, smooth and shiny; T2 subtriangular, 3 × as wide as long, smooth except few punctations; hypopygium sclerotized, folded medially and blunt at apex; ovipositor sheaths small and thick, slender with bluntly rounded tips, 0.7 × as long as hypopygium and 0.9 × longer than hind basitarsi, hairy at apical one third, arising below at mid length of valvifer; ovipositor weakly curved downward.

Male
Same as holotype except antennae longer than body length, F1-F3 with double rank of placodes.

Remarks
Pholetesor indicus sp. nov. can be distinguished from all previously described species by the unique combination of characters as follows: ocelli large; scutellum highly polished; propodeum almost 2 × as wide as long, largely smooth except antero-medially punctate with long hairs, posterior corners somewhat weakly rugulose; T1 3.6 × as long as its apical width and 1.8 × its basal width, distinctly narrowed apically, smooth and shiny; T2 subtriangular, 3 × as wide as long, smooth except few punctations; T3 rectangular, 1.40 × as long as T2, unsculptured; hypopygium sclerotized, folded medially and blunt at apex; ovipositor sheaths small and thick, slender with a bluntly rounded tips, 0.7 × as long as hypopygium, hairy at apical one third, arising below at mid length of valvifer; ovipositor weakly curved downward.

Discussion
The genus Pholetesor almost exclusively attacks leaf-mining Lepidoptera (Whitfield 2006). Prior to the current study, only one species of Pholetesor was described from India. However, within such a large expanse of land, covering more 3.2 million km 2 , many more species await discovery. Approximately 21% of the country's landmass is covered by forests (tree canopy density >10%), of which 12% comprises moderately or very dense forests (tree canopy density >40%) (CBD 2014). These include tropical rainforests of the Andaman Islands, the Western Ghats and Northeast India; coniferous forests of Himalaya; deciduous Sal (Shorea robusta Gaertn.) forest of Eastern India; the dry deciduous Teak (Tectona L.f. spp.) forest of Central and Southern India; and the Babul (Acacia Mill.) dominated thorn forest of the Central Deccan and Western Gangetic plain (Tritsch 2001).
Our findings of three species of the genus Pholetesor reared from the leaf-mining lepidopteran larvae from the trees near the agrarian ecosystem provide important evidence that the wild area, as well as suburban areas (city parks) near the agrarian ecosystem could have more species fauna in the surrounding territories (Owen et al. 1981;Ahmad & Ghramh 2018;Banaszak-Cibicka et al. 2018;Ahmad et al. 2019;Ghramh et al. 2019). The North Indian landscape is covered mostly by the agrarian ecosystem, where Lepidoptera are the key pests. The agrarian ecosystem is nevertheless rich in natural habitats, including small pockets of natural forests, and hosts a very diverse array of insects (CBD 2014). Indeed, the presence of a natural wild reserve, near to suburban areas, can play a crucial role as a biodiversity reservoir from which beneficial species can spill over and colonize or decolonize perturbed areas.
Among the three new species two, P. acrocercophagus sp. nov. and P. indicus sp. nov., are readily placed in the ʻcircumscriptus-groupʼ of species of Pholetesor. Both the new species were differentiated from P. circumscriptus and P. bicolor, two species with a wide distribution range and demonstrating quite a large degree of variability in morphology according to their host and ecological preferences. Owing to this morphological variation, the delimitation of the new species is quite problematic. Shaw (2012) clearly addressed this problem and provides the detailed discussion about differentiating P. bicolor and P. circumscriptus. Shaw (2012) has added strong evidence (biological and morphological data) that support P. bicolor and P. circumscriptus being considered as different species and also mentioned that these species are likely to be a complex of cryptic species. Other two species, P. camerariae sp. nov. and P. hayati can be placed under ʻornigis-groupʼ of species of the genus Pholetesor on the basis of the overall shape and sculpture patterns of propodeum and first metasoma tergite.