Revision on Palaearctic species of Periclistus Förster with description of a new species and its host plant gall (Hymenoptera, Cynipidae)

Abstract Palaearctic species of Periclistus Förster has been systematically described, but a new inquiline gall-wasp, Periclistus qinghainensis sp. n., is described from China. This species was obtained from an unknown stem gall induced on Rosa sp. Diagnosis, distribution and biology of the new species are described in this paper. After examining the types of Periclistus idoneus Belizin, 1973 and Periclistus capillatus Belizin, 1968, it is concluded that Periclistus idoneus belongs to genus Aulacidea, and Periclistus capillatus is a valid species of Periclistus. A key to the Palaearctic Periclistus species is also given.


Introduction
Synergini is an important tribe of the family Cynipidae (Hymenoptera) with a worldwide distribution. They are biologically characterized for being inquilines: although they have lost the ability to induce galls, they are still able to directly modify the gall tissue that surrounds them, inducing the characteristic nutritive tissue usually found in the larval chambers of the gall-inducers (Melika 2006). All inquilines are wholly phytophagous, some of them being lethal if they compete with the inducer for the food in the same larval chamber. This lifestyle represents a unilateral relationship only beneficial for the inquiline (Askew 1984).
Periclistus is a small genus with 14 species distributed across the Holarctic region, three of them having an uncertain status: P. idoneus Belizin, 1973, P. mongolicus Belizin, 1973and P. capillatus Belizin, 1968(Taketani and Yasumatsu 1973. Despite being morphologically similar to Synophromorpha Ashmead, Periclistus can be distinguished by the following characters (Ritchie and Shorthouse 1987): uniformly and delicately coriaceous mesoscutum (graniculate or smooth in Synophromorpha); notauli never complete, forming two short sulci not posteriorly broadened (complete and distinctly broadened notauli in Synophromorpha), ventral margin of subalar triangle with a row of setigerous punctures (without a row of setigerous punctures in Synophromorpha), closed radial cells (opened radial cells in Synophromorpha and Japanese species of Periclistus), and the male's third flagellomere usually strongly notched and distally broadened (third flagellomere weakly curved, broadly notched and weakly expanded distally in Synophromorpha). Both genera form a monophyletic group, as has been demonstrated by several authors (Ritchie and Shorthouse 1987;Ronquist and Liljeblad 2001;Nylander 2004, among others). Here genus Periclistus is firstly reported from China, with a new species Periclistus qinghainensis sp. n., found in a gall on an unidentifies species of Rosa induced by an unknown species in Diplolepis.

Materials and methods
The types of P. idoneus and P. capillatus described by Belizin from Hurfeish (Israel) and Primorskij Kraj (Russian Far East) respectively, have been examined in this study. * In the monent to publish this manuscript the Synergini is reestructred according to Ronquist et al. (2015) They are deposited in ZIN (Zoological Institute of the Russian Academy Sciences, St. Petersburg, Russia).
The galls of the new species described here were collected on May 2010 in the north western province of Qinghai of China. During this month the weather is still cold, the branches of trees are still covered by snow and the useful characters to determine the Rosa species are not present in the plant, so it was impossible to identify it; in addition, in China there are approximately 100 described species of Rosa, making it hard to establish a potential candidate. Hence, the galls were sent to Y. Wang without determination of Rosa species.
The current terminology describing the cynipid gall-wasp morphology follows Liljeblad and Ronquist (1998) and Melika (2006). Abbreviations for the forewing venation are taken from Ronquist and Nordlander (1989) and those for the cuticular surface from Harris (1979). Measurements and abbreviations used here include F1-F12 for first and subsequent flagellomeres. Other abbreviations are: post-ocellar distance (POL), the distance between the inner margins of the posterior ocelli; ocellarocular distance (OOL), the distance from the outer edge of the posterior ocellus to the inner margin of the compound eye; and lateral-ocullar distance (LOL), the distance between lateral and frontal ocelli. The width of the forewing radial cell was measured from the margin of the wing to the Rs vein.
Measurements were made under a Leica MZ 12.5 stereomicroscope (Wetzlar, Germany), and photos were taken with a digital camera (Q-Imaging, Micropublisher 3.3 RTV) attached to the Leica MZ APO stereomicroscope (Wetzlar, Germany) using software of Synoptics Auto-Montage version 5.0.
Specimens of the new species are deposited in the Hymenoptera Collection in Zhejiang A & F University (ZAFU) and the University of Barcelona (UB), respectively.
Diagnosis. This species is characterized by the following characters: black head and mesosoma, chestnut brown to black metasoma, testaceous antennae and legs; 12-segmented antenna, F1 and F2 subequal in length (4:5); an alutaceous mesoscutum with piliferous points and sparse pubescence; notauli and posterior medial sulcus present, short, both extending to ¼ of total scutum length; parapsidal lines and anterior parallel lines present; smooth mesopleuron; closed radial cell (although both R1 and its projection in margin of forewing nearly inconspicuous), short, 3 times as long as broad; areola visible; metasomal tergites fused (T2+T3) and smooth, with an anterolateral patch of white setae; the subsequent segments are micropunctuated and glabrous.
Comments. This species presents characters belonging to Asian species (scutal and mesopleural sculpture) and characters belonging to European species (radial cell length and shape). A key provided at the end differentiates this species from its congeners.
Comments. After examining the holotype, we conclude that this species belongs to genus Aulacidea. After determining the specimen following the Palaearctic Aulacidea species key made by Melika (2006) we conclude that this species is a valid species related to A. laureae Nieves-Aldrey, 1992 and A. follioti Barbotin, 1972. The three species present the head broader than high, 13-segmented antenna, F1 shorter than F2, incomplete notauli and ciliated forewing margin. Aulacidea idoneus differs from A. follioti in presenting median mesoscutal line, like A. laureae; A. idoneus can be distinguished from A. laureae by the following characters: short and narrow scutelar foveae, OOL 3.0 times longer than the diameter of lateral ocellus, space between totuli and clypeus without radiating carina, having shorter notauli and medial mesoscutal line shorter (both extending 1/3 of scutum length) and radial cell (slightly more than 2.0 times longer than broad) and having a second metasomal tergite with only some dorsal points while being laterally smooth.

Periclistus mongolicus Belizin, 1973, species dubia
Periclistis mongolicus Belizin, 1973: 26. Remarks. This species described from Mongolia was considered by Abe et al. (2007) as having an uncertain status until the types were revised. Because of the loss of the type material (S. Belokobylskij pers. comm.) this species is definitively considered as 'species dubia' according to the description, which does not permit assessment of its validity nor its placement in the genus Periclistus.
Periclistus qinghainensis sp. n. http://zoobank.org/C0EA8F5E-6EAB-4B2F-B77B-1F97332B6066 Figs 1-2 Diagnosis. Periclistus qinghainensis sp. n. differs from all of the known Periclistus species in the absence of notauli. Periclistus qinghainensis sp. n. is morphologically similar to two Japanese species (P. natalis Taketani & Yasumatsu and P. quinlani Taketani & Yasumatsu) and the Far East Russian species (P. capillatus) in having a smooth and shiny mesoscutum (very weakly alutaceous in P. capillatus) with dispersed piliferous points and smooth mesopleuron, but it differs from all these species in having a partially closed radial cell (radial cell opened in P. natalis and P. quinlani while closed and shorter in P. capillatus), shorter F1 than F2 (F1 and F2 subequal in P. natalis and P. quinlani) and the absence of notauli (present in the other three species). Periclistus qinghainensis sp. n. differs from the European species in having the radial cell partially closed (closed in P. caninae (Hartig) and P. brandtii Ratzeburg), a smooth and shiny mesoscutellum (uniformly and delicately coriaceous scutellum with a dense and short pilosity without piliferous points in the European species) and the length and width of the radial cell (more than 4.0 times as long as wide in P. qinghainensis while around 3.0 times in P. brandtii and P. caninae).
Description. Length. Female. Body length 2.1 mm, and fore wing 2.8 mm.
Colour. Body black, except yellow tegulae and antennae, scapus and apical flagellomere darker; coxae dark brown, rest of the legs yellowish; forewing hyaline, with brown veins.
Head (Fig. 1a, b). Head coriaceous, with sparse setae, 2.0 times wider than long in dorsal view, 1.4 times wider than high in front view and slightly wider than mesosoma. Gena delicately coriaceous and not broadened behind eyes. Clypeus very small, impressed quadrangular and delicately coriaceous, ventrally slightly rounded; slightly higher than wide, with distinct small anterior tentorial pits, epistomal sulcus and clypeo-pleurostomal lines indistinct. Lower face with striae radiating from clypeus, not reaching eyes and antennal socket, median elevated area delicately coriaceous and striated. Malar space 0.3 times longer than eye height. Diameter of antennal torulus 2.0 times longer than inter-toruli distance and 1.1 times longer than eye-torulus distance. POL: OOL: LOL=1.7: 0.6: 1.3. Frons, vertex, and gena behind eyes and postgena with sparse setae. Frons largely smooth, with some very small and distinct punctures but without lateral frontal carina. Vertex and occiput uniformly punctured.
Metasoma. Female (Fig. 1d). metasoma nearly as long as head plus mesosoma, distinctly longer than height in lateral view; metasomal tergites 2+3, with patches of dense setae at laterals in its base, fifth and sixth metasomal tergites broadly punctuate dorso-posteriorly; prominent part of ventral spine of hypopygium very short. Male. second and third metasomal tergites not fused, separated by a suture.
Distribution. China (Qinghai). Biology. Reared from stem galls on Rosa sp. (Fig. 1g and h). The young gall is juicy, soft, covered with small raised tubercles, and multilocular with greenish-purple spots, 1.0-2.0 cm in diameter. Adults emerge in September.
Etymology. The new species is named after the province where it was collected.
Periclistus species are associated with Diplolepis and Liebelia galls, except P. smilacis, a Nearctic species known from Florida reared in galls of Diastrophus smilacis (Ashmead 1896;Penzes et al. 2012), although M. Buffington and M. Gates (pers. comm.) disagree and consider P. smilacis should be associated with some Diplolepis species. Abe et al. (2007) placed Periclistus capillatus and P. mongolicus in an 'uncertain status' and the original description of P. idoneus does not allow one to discriminate this species from P. caninae and P. brandtii, except for the shorter radial cell present in P. idoneus. After examining the type material of Periclustus capillatus we considered it is a valid species. Unfortunately, the type material of P. mongolicus is lost, so we were not able to study it and we considered this species 'incertae sedis'. Finally, when examining the holotype of P. idoneus we concluded that it was a valid species belonging to the genus Aulacidea.
Periclistus natalis and P. quinlani are morphologically very similar (both having complete shallow notauli, smooth and shiny mesopleuron, and opened radial cell of the forewing), and share the same gall host (Diplolepis japonica (Walker)) and host plant (Rosa polyantha Sieb. & Zucc.); however, the authors of these species (Taketani and Jasumatzu 1973) described biological differences between them. Abe (1998) studied the type material of these two species and concluded that there was only one morphological character different between the two species, viz. the pits of the notauli are weakly present anteriorly in P. natalis, and absent in P. quinlani. Nevertheless, this difference is very superficial based on our knowledge of morphology of Cynipidae; with additional data, it is very probable that both species will be synonymized.
The species described here, Periclistus qinghainensis, is similar to two Japanese species (P. natalis and P. quinlani) and a Far Eastern Russian species (P. capillatus). They share a punctured mesoscutum and smooth and shiny mesopleuron. These characters are exclusive of these four species from the rest of the Eastern Palaearctic Periclistus. Periclistus qinghainensis presents a partially closed radial cell, an intermediate characteristic between the open radial cell of the Japanese species and the remaining of Palaearctic species (P. caninae and P. brandtii both present a closed radial cell). As mentioned above, P. capillatus is intermediate between the Japanese and Chinese species and the remaining of Palaearctic species Forewing with the radial cell partially closed (Fig. 2e-