Introduction Charipinae are small parasitoid wasps which are hyperparasitic on aphids ( Hemiptera : Aphidoidea ) via Aphidiinae ( Hymenoptera : Ichneumonoidea : Braconidae ) and Aphelininae ( Hymenoptera : Chalcidoidea : Aphelinidae ) and also hyperparasitoids of psyllids ( Hemiptera : Psylloidea ) 

Type material of the species of Alloxysta described by Cameron and Fergusson and deposited in the Natural History Museum of London has been revised. Seven species are considered valid: Alloxysta abdera Fergusson, 1986, A. basimacula (Cameron, 1886), A. crassa (Cameron, 1889), A. mullensis (Cameron, 1883), A. piceomaculata (Cameron, 1883), A. pleuralis (Cameron, 1879) and A. semiaperta Fergusson, 1986. A. basimacula, A. crassa, A. maculicollis (Cameron, 1886), A. perplexa (Cameron, 1889) and A. piceomaculata are here removed from synonymy with A. macrophadna (Hartig, 1841). A. rufi ceps (Cameron, 1883) is removed from synonymy with A. victrix (Westwood, 1833). A. caledonica (Cameron, 1886) and A. perplexa are here synonymized with A. basimacula. A. maculicollis, A. rufi ceps and A. rufi collis (Cameron, 1883) are here synonymized with A. castanea (Hartig, 1841). A. ancylocera (Cameron, 1886) was correctly synonymized with A. fuscicornis (Hartig, 1841), A. curvicornis (Cameron, 1883) was correctly synonymized with A. victrix and A. fi licornis (Cameron, 1889) was correctly synonymized with A. macrophadna. Complete redescriptions and illustrations are given for valid species. A key for all the Alloxysta species found so far in Great Britain is given.


Introduction
Charipinae are small parasitoid wasps which are hyperparasitic on aphids (Hemiptera: Aphidoidea) via Aphidiinae (Hymenoptera: Ichneumonoidea: Braconidae) and Aphelininae (Hymenoptera: Chalcidoidea: Aphelinidae) and also hyperparasitoids of psyllids (Hemiptera: Psylloidea) via Encyrtidae (Hymenoptera: Chalcidoidea).They are an important negative infl uence on the benefi cial biological control of primary parasitoids, and so it is necessary to identify them to species level before undertaking any studies of the biological control process.The chaotic status of the taxonomy of Charipinae has led us to study all the type material belonging to this subfamily, especially Alloxysta, since it is the most numerous (111 valid species according to Ferrer-Suay et al. 2012a), diverse and widely distributed genus.This is because the original descriptions are often very simple, without the necessary diagnostic characters and without comparisons to similar species.The best way to solve the taxonomy of a group is by characterising species, and then assigning names to those species by studying the characteristics of the type.These specimens are deposited in several institutions distributed around the world, especially in Europe.
With this aim we studied the types of Peter Cameron and Nigel D.M. Fergusson deposited in the Natural History Museum, London.The type material of Alloxysta, housed in the following collections, has already been revised: the Carl G. Thomson and Johan W. Zetterstedt collections deposited at the Lund Museum of Zoology, Sweden (Ferrer-Suay et al. 2013), the Vladimir I. Belizin collection deposited at the Zoological Institute of the Russian Academy of Sciences, Saint Petersburg, Russia (Ferrer-Suay et al. 2012b), the Mihail A. Ionescu collection deposited at the "Grigore Antipa" National Museum of Natural History, Bucharest, Romania (Ferrer-Suay et al. 2012c), the Theodor Hartig collection deposited at the Zoologische Staatssammlung Museum, München, Germany (Ferrer-Suay et al. in press), the Wolter Hellén collection deposited at the Finnish Museum of Natural History, Helsinki, Finland (Ferrer-Suay et al. in prep.), the John Curtis collection deposited at the National Museum of Victoria, Melbourne, Australia (Ferrer-Suay et al. in press), and the Fred G. Andrews, William H. Ashmead and Charles F. Baker collections deposited at the United States National Museum of Natural History (Smithsonian Institution), Washington DC, USA and at the Canadian National Collection of Insects, Ottawa, Canada (Ferrer-Suay et al. in press).
Charipinae are very small wasps, with a smooth and shiny body and with little interspecifi c variability.The early species descriptions of Charipinae were very short, mainly focused on coloration or size, and leaving out important characters which are essential nowadays to identify species.The most important diagnostic features used to distinguish between species of Alloxysta are: i) proportions of fl agellomeres; ii) size and shape of radial cell; iii) presence or absence of pronotal carinae; and iv) presence or absence of propodeal carinae, and if present, the shape of the carinae.We have focused on these characters to establish whether each nominal species is valid or a synonym of another species.
The species described by Fergusson (1986), Alloxysta abdera and A. semiaperta, which are currently considered valid, were also examined in detail for this study.
All valid species have been redescribed and their important features illustrated.Redescriptions are needed because the original ones are inadequate as mentioned above.

Material and Methods
The type specimens were borrowed from The Natural History Museum, London (BMNH).They were studied using stereo microscopy and were photographed using a Zeiss Discovery V8 compound microscope with an attached INFINITYX-21C digital camera feeding image fi les to a notebook or desktop computer; the program DeltaPix View-Pro AZ was then used to merge an image series (typically representing 20 focal planes) into a single in-focus image.All photographed specimens belong to type material.Paretas-Martinez et al. (2007).Measurements and abbreviations include F1-F12, fi rst and subsequent fl agellomeres.The width of the forewing radial cell was measured from the margin of the wing to the edge of vein Rs.The transfacial line ratio was calculated by dividing the length of the transfacial line (measured from the inner margins of compound eyes, across the face through the antennal sockets) by the compound eye height.The malar space ratio was calculated by dividing the length of the lower part of the gena (from the mouthparts to the ventral margin of the compound eye) by the compound eye height.Females and males of each species have the same characters except where indicated in redescriptions.

Morphological terms used follow
The species are treated here in alphabetical order.

Redescription
COLORATION.Head yellowish brown, mesosoma and metasoma very dark brown.Antennae dark yellow.Legs yellow and veins yellowish brown.HEAD.Transversely ovate, smooth and shiny, wider than high in front view; with setae below, between and a few above toruli.With few setae on vertex and with many setae on face.Transfacial line 1.0 x height of compound eye.Malar space 0.6 x height of compound eye.
MESOSOMA.Pronotum covered with abundant setae, less setae on anterior margin, with two thick carinae clearly visible under the pubescence (Fig. 1B).Mesoscutum smooth and shiny, round in dorsal view with scattered setae.Scutellum also smooth and shiny with few scattered setae, being abundant on apex.Height of mesopleural triangle along anterior margin 1.6 x the height of mesopleuron.Propodeum entirely covered by setae, with two carinae forming a thick plate, with setae on top and sides slightly curved (Fig. 1E).FORE WING.Longer than body, 1.4 x as long as mesosoma and metasoma together in both male and female (Fig. 1A).Covered with dense pubescence; marginal setae present.Completely open radial cell, 2.2 x as long as wide in both male and female.R1 short and curved; Rs long and curved.R1 and Rs not reaching costal margin (Fig. 1F).
METASOMA.Anterior part with an incomplete ring of setae, glabrous at centre, wider laterally.Metasoma smooth and shiny, T3 and T4 clearly distinguished.

Remarks
According to the original description, Alloxysta abdera is represented by 9 specimens (6 ♂♂ and 3 ♀♀) in BMNH.One male was designated as holotype by Fergusson and the rest of the specimens as paratypes; we have examined only the holotype (♂) and one paratype (♀).This species is very similar to A. pallidicornis (Curtis, 1838) because both species have a completely open radial cell, pronotal and propodeal carinae present, and fl agellomeres club-shaped and with rhinaria from F2, but they differ in the ratios between F2 and F3.F3 is slightly longer than F2 in A. abdera (Fig. 1C), whereas in A. pallidicornis F2 is longer than F3; size of radial cell: 2.2 x as long as wide in A. abdera (Fig. 1F) but 2.6 x as long as wide in A. pallidicornis; shape of propodeal carinae: with two carinae forming a thick plate, with setae on top and sides slightly curved in A. abdera (Fig. 1E) but with two carinae well defi ned and separated by setae in the fi rst half and forming a plate in the last half in A. pallidicornis.(Cameron, 1886)

Redescription
COLORATION.Head yellowish brown, mesosoma and metasoma brown.Scape, pedicel and F1-F3 dark yellow; F4-F11 brown.Legs dark yellow and veins yellowish brown.HEAD.Transversely ovate, smooth and shiny, wider than height in front view; with setae below, between and a few above toruli.With few scattered setae on vertex and with many setae on face.Transfacial line 1.1 x height of compound eye.Malar space 0.4 x height of compound eye.
MESOSOMA.Pronotum covered by abundant setae, less at central area and distolateral margins; with two long, thick, clearly visible carinae (Fig. 2C).Mesoscutum smooth and shiny, round in dorsal view, with scattered setae.Scutellum also smooth and shiny, with few scattered setae, abundant on apex of scutellum.Height of mesopleural triangle along anterior margin 0.7 x height of mesopleuron.Propodeum covered by abundant setae, without carinae (Fig. 2E).(Cameron, 1886) FORE WING.Longer than body, 1.6 x as long as mesosoma and metasoma together (Fig. 2A).Covered with dense pubescence; marginal setae present.Completely open radial cell, 3.0 x as long as wide.R1 short and straight; Rs long and slightly curved (Fig. 2B).

Remarks
Alloxysta basimacula was synonymized with A. macrophadna (Hartig, 1841) by Fergusson (1986).After studying the type material, it is here considered as a different and valid species.The type series of this species consists of the lectotype female and one paralectotype male.Only the lectotype has been studied here.
Alloxysta caledonica was synonymized with A. macrophadna (Hartig, 1841) by Fergusson (1986).It is represented in BMNH only by the holotype female.After studying the holotype of A. caledonica, it was found to be the same species as A. basimacula, so these two species are synonymized here.
Alloxysta perplexa was also synonymized by Fergusson (1986) with A. macrophadna (Hartig, 1841).A. perplexa is represented in BMNH by the lectotype female and ten paralectotypes (8 ♂♂ and 2 ♀♀).Comments on the type series of A. perplexa were given by Quinlan (1978: 125).However, after comparing the lectotype of A. perplexa with A. macrophadna, we found that they can be differentiated by the shape of the radial cell, completely open in A. perplexa and partially open in A. macrophadna.The main features of A. perplexa are coincident with those of A. basimacula; for this reason we establish here this new synonymy.(Hartig, 1841) Xystus castaneus Hartig, 1841: 352

Remarks
Alloxysta maculicollis was synonymized with A. macrophadna (Hartig, 1841) by Fergusson (1986).Alloxysta maculicollis is represented in BMNH by the lectotype female.According to Quinlan (1978: 125), there are other specimens in the BMNH collection with a handwritten name "maculicollis" on the reverse side which are not considered to be syntypic.After studying the A. maculicollis type material it was found that it is different from A. macrophadna, mainly because the propodeal carinae are present forming a plate, which is not the case for A. macrophadna.Alloxysta maculicollis agrees with A. castanea in all signifi cant characters, so they are synonymized here.
Alloxysta rufi ceps was synonymized by Fergusson (1986) with A. fulviceps (Curtis, 1838).According to Pujade-Villar et al. (2011), A. fulviceps (Curtis) is a synonym of A. victrix (Westwood, 1833).Alloxysta rufi ceps is represented in BMNH only by the holotype male.After studying this specimen, we found that it is the same species as A. castanea, because they both have: partially open radial cell, pronotal carinae present and propodeal carinae forming a plate, and the same proportion between fl agellomeres.For these reasons, we here synonymize A. rufi ceps with A. castanea.Alloxysta rufi collis is represented in BMNH by only one specimen (female).It was considered to be the holotype by Quinlan (1974: 9), but according to the last label added to this specimen, it cannot be the holotype because Cameron did not designate a holotype and there is no evidence that the species was based on only one specimen (monotypy).Moreover, the original description was based on a male (although it is possible that Cameron misinterpreted the sex).For these reasons, this specimen is considered as a syntype and we here designate it as the lectotype.Alloxysta rufi collis was synonymized by Quinlan with Alloxysta erythrothorax (Hartig, 1840) and later Evenhuis (1972) synonymized it with A. castanea.Van Veen (pers.com.) considered A. rufi collis to be a valid species, with A. megaptera (Cameron, 1889) as its synonym (Ferrer-Suay et al. 2012a).After comparing this species with other Alloxysta, we conclude that Evenhuis was correct.
HEAD.Transversely ovate, smooth and shiny, wider than high in front view.With setae below, between and a few above toruli.With few scattered setae on vertex and with many setae on face.Transfacial line 1.2 x height of compound eye.Malar space 0.5 x height of compound eye.
MESOSOMA.Pronotum covered by abundant setae, less at distolateral margins; with two thick, clearly visible carinae (Fig. 3D).Mesoscutum smooth and shiny, round in dorsal view, with scattered setae.Scutellum also smooth and shiny, with few scattered setae, abundant on apex of scutellum.Height of mesopleural triangle along anterior margin 0.9 x height of mesopleuron.Propodeum covered by abundant setae, propodeal carinae absent (Fig. 3F).FORE WING.Longer than body, 1.5 x as long as mesosoma and metasoma together (Fig. 3A).Covered with dense pubescence; marginal setae present.Completely open radial cell, 2.8 x as long as wide.R1 short and straight; Rs long and slightly curved (Fig. 3C).
METASOMA.Anterior part with an incomplete ring of setae, glabrous at centre, wider laterally.Metasoma smooth and shiny, T3 and T4 clearly distinguished.

Remarks
This species was synonymized by Fergusson (1986) with A. macrophadna (Hartig, 1841).Alloxysta crassa is represented in BMNH by the lectotype female and 3 paralectotype females.Comments on the type series of A. crassa are presented in Quinlan (1974: 7).However, after revising the lectotype we found that it is a different and valid species.Alloxysta crassa can be differentiated from A. macrophadna by the shape of the radial cell: completely open in A. crassa (Fig. 3C) while partially open in A. macrophadna; relation between fl agellomeres: F2 longer than F1 and F3 in A. crassa (Fig. 3B), whereas F2 is subequal to F1 and slightly longer than F3 in A. macrophadna.(Hartig, 1841) Xystus fuscicornis Hartig, 1841: 352.Allotria ancylocera Cameron, 1886: 85 (synonymized in Evenhuis 1982: 23).

Remarks
Alloxysta fi licornis is represented by the holotype male and fi ve paralectotype males at BMNH.According to Quinlan's notes (1978: 125), there is another conspecifi c male from England, but it is not considered a paralectotype, because the Cameron's original description stated that the specimens were collected only in Scotland.This species was synonymized by Fergusson (1986) with A. macrophadna (Hartig, 1841) and the validity of this synonymy is confi rmed here.(Cameron, 1883) Fig. 4 Allotria mullensis Cameron, 1883: 366.

Redescription
COLORATION.Head brown, mesosoma and metasoma dark brown.Pedicel, scape and F1-F3 dark yellow; F4-F11 yellowish brown.Legs and veins yellow.HEAD.Transversely ovate, smooth and shiny, wider than high in front view.With setae present below and between toruli.Without setae on vertex and with a lot of setae on frons.Transfacial line 1.3 x the height of compound eye.Malar space 0.5 x the height of compound eye.
MESOSOMA.Pronotum covered by sparse setae except a small area of the center, few setae on distolateral corners; without carinae (Fig. 4C).Mesoscutum smooth and shiny, round in dorsal view with few scattered setae.Scutellum also smooth and shiny, also with sparse setae.Height of mesopleural triangle along anterior margin more or less 1.3 x height of mesopleuron.Propodeum covered by abundant pubescence; two wide propodeal carinae separated by few setae on top and forming a plate on bottom; sides sub-parallel anteriorly and very slightly curved posteriorly (Fig. 4D).FORE WING.Longer than body, 1.5 x as long as mesosoma and metasoma together.Forewing covered by abundant pubescence; marginal setae present (Fig. 4A).Radial cell closed, 2.2 x as long as wide (Fig. 4B).R1 short and straight; Rs longer than R1 and curved.
METASOMA.Proximal part with an incomplete ring of setae, setae absent in the center and present laterally.Remainder of metasoma smooth and shiny, with terga clearly visible.

Remarks
The type series of Alloxysta mullensis is represented by one specimen in BMNH.It was designated as the lectotype in Ferrer-Suay et al. (2012d).This species was synonymized with A. brevis (Thomson, 1862) by Fergusson (1986) as were A. arcuata (Kieffer, 1902) and A. castaneiceps (Kieffer, 1904).This "brevis group" is represented by very small specimens, with small closed radial cells, small fl agellomeres very similar to each other and a propodeal plate in the center of the propodeum.The "brevis group" has been tackled in a previous study (Ferrer-Suay et al. 2012d), who concluded that A. mullensis should be considered a valid species.Alloxysta mullensis differs from A. brevis in the proportion of antennomeres: F1 subequal to pedicel in A. mullensis but shorter than pedicel in A. brevis, and F1 longer than F2 in A. mullensis while subequal to F2 in A. brevis.Furthermore, A. mullensis differs from A. arcuata in lacking pronotal carinae, which are present in A. arcuata.(Cameron, 1883) stat.rev.

Redescription
COLORATION.Head, mesosoma and metasoma yellowish brown.Scape, pedicel and F1-F2 dark yellow; F3-F11 brown.Legs and veins dark yellow.HEAD.Transversely ovate, smooth and shiny, wider than high in front view.With setae below and between toruli and a few setae above toruli.With few scattered setae on vertex and with many setae on face.Transfacial line and malar space cannot be measured due to the position of the type specimen.ANTENNA.Female: 13-segmented, fi liform.All antennomeres covered with sparse setae.F1-F3 thinner and smoother than remaining fl agellomeres; F4-F11 club-shaped, with rhinaria.Pedicel 1.9 x as long as wide; F1 1.4 x as long as wide; F2 2.4 x as long as wide; F3 2.6 x as long as wide; F4 2.1 x as long as wide.F1 1.2 x as long as pedicel; F1 1.4 x as long as F2; F3 1.1 x as long as F2; F3 subequal to F4; F4-F11 subequal in length, width and shape (Fig. 5D).Male unknown.
MESOSOMA.Pronotum covered by abundant setae, with two long and thick, clearly visible carinae (Fig. 5F).Mesoscutum smooth and shiny, round in dorsal view, with scattered setae.Scutellum also smooth and shiny, with few scattered setae, abundant on apex of scutellum.Height of mesopleural triangle along anterior margin 1.3 x height of mesopleuron.Propodeum covered by abundant setae, propodeal carinae absent (Fig. 5C).FORE WING.Longer than body, 1.8 x as long as mesosoma and metasoma together (Fig. 5A), covered with dense pubescence; marginal setae present.Open radial cell, 2.8 x as long as wide.R1 short and straight; Rs long and slightly curved (Fig. 5B).
METASOMA.Anterior part with an incomplete ring of setae, glabrous at centre, wider laterally.Metasoma smooth and shiny, T3 and T4 clearly distinguished.

Remarks
The type series of Alloxysta piceomaculata is represented by the lectotype female and one paralectotype male.This species was synonymized with A. macrophadna (Hartig, 1841) by Fergusson (1986).After studying the type material, we found it was different from A. macrophadna and therefore it is here considered a valid species.This species is similar to Alloxysta nigrita (Thomson, 1862) in having a completely open radial cell, pronotal carinae present, propodeal carinae absent, and fl agellomeres club-shaped and with rhinaria from F4.However, they can be differentiated by the relative length/width of F1: 1.4 x as long as wide in A. piceomaculata, but 4.4 x in A. nigrita; ratio between the lengths of F3 and F4: F3 subequal to F4 in A. piceomaculata but longer than F4 in A. nigrita.(Cameron, 1879) Fig. 6 Allotria pleuralis Cameron, 1879: 113.

Redescription
COLORATION.Head dark yellow, mesosoma yellowish brown and metasoma dark brown.Scape, pedicel and F1-F3 dark yellow; F4-F12 brown.Legs and veins dark yellow.HEAD.Transversely ovate, smooth and shiny, wider than high in front view.With setae below and between toruli and a few setae above toruli.With few or without setae on vertex and with many setae on face.Transfacial line 1.1 x height of compound eye.Malar space 0.5 x height of compound eye.
MESOSOMA.Pronotum covered with sparse setae, with two thick, clearly visible carinae (Fig. 6B).Mesoscutum smooth and shiny, round in dorsal view, with scattered setae.Scutellum smooth and shiny, with few scattered setae, abundant on apex of scutellum.Height of mesopleural triangle along anterior margin 1.3 x height of mesopleuron.Propodeum covered by setae, with two well defi ned carinae reaching the base independently, thick and with curved sides (Fig. 6E).FORE WING.Longer than body, 1.4 x as long as mesosoma and metasoma together (Fig. 6A).Covered with dense pubescence; marginal setae present.Partially open radial cell, 2.1 x as long as wide.R1 short and curved; Rs long and also curved (Fig. 6A).
METASOMA.Anterior part with an incomplete ring of setae, glabrous at centre, wider laterally.Metasoma smooth and shiny, T3 and T4 clearly distinguished.

Remarks
Alloxysta pleuralis is represented in BMNH by three specimens (females).However, in Cameron's original description fi ve specimens were mentioned.The two other specimens were not found by Quinlan (1974: 9).Of the three remaining specimens, one was designated the lectotype and the other two were considered as paralectotypes by Quinlan (1974: 8).Alloxysta pleuralis is easily distinguished from other Alloxysta species by its combinations of features, especially the shape of the propodeal plate, which is unique for this species.Fergusson, 1986 Fig. 7 Alloxysta semiaperta Fergusson, 1986: 11.

Redescription
COLORATION.Head, mesosoma and metasoma dark brown.Scape, pedicel, F1 and F2 yellow; F3-F11 brown.Legs yellow and veins yellowish brown.HEAD.Transversely ovate, smooth and shiny, wider than high in front view.With setae below, between and a few above toruli.Few setae on vertex and with many setae on face.Transfacial line 1.1 x height of compound eye.Malar space 0.4 x height of compound eye.
MESOSOMA.Pronotum covered with abundant setae, less setae on anterior margin, with two thick, clearly visible carinae (Fig. 7G).Mesoscutum smooth and shiny, round in dorsal view, with scattered setae.Scutellum also smooth and shiny, with few scattered setae, abundant on apex of scutellum.Height of mesopleural triangle along anterior margin 2.2 x height of mesopleuron.Propodeum with many setae, without carinae (Fig. 7E).FORE WING.Longer than body, 1.7 x as long as mesosoma and metasoma together (Fig. 7A).Covered with dense pubescence; marginal setae present.Partially open radial cell, 2.7 x as long as wide.R1 short and curved; Rs long and also curved (Fig. 7B).
METASOMA.Anterior part with an incomplete ring of setae, glabrous at centre, wider laterally.Metasoma smooth and shiny, T3 and T4 clearly distinguished.

Remarks
Alloxysta semiaperta is represented in BMNH by 7 males and 25 females.One female was designated by Fergusson as the holotype and the rest paratypes.This species is very similar to A. macrophadna (Hartig, 1941), because both have the radial cell partially open, pronotal carinae present and propodeal carina absent, but they differ in the proportions of the fl agellomeres in both male and female: F2 shorter than F3 and F3 shorter than F4 in females of A. semiaperta (Fig. 4B), whereas F2 is longer than F3 and F3 subequal to F4 in females of A. macrophadna.Males of A. semiaperta have F1 longer than F2 and F3 shorter than F4, without any curved fl agellomeres (Fig. 4C), whereas males of A. macrophadna have F1 subequal to F2 and F3 shorter than F4, F2 and F3 curved.(Westwood, 1833) Allotria victrix Westwood, 1833: 495. Allotria curvicornis Cameron, 1883: 366 (synonymized in Fergusson 1986: 11).

Remarks
Alloxysta curvicornis is represented only by the holotype male at BMNH.This species was synonymized with A. victrix (Westwood, 1833) by Fergusson (1986: 11).The type material of this species has been revised and the validity of this synonymy is here confi rmed.

Conclusions
Following this revision of the Cameron and Fergusson types deposited at the Natural History Museum, London, it was found that many of the synonymies established by Fergusson (1986: 10) were wrong.Within Alloxysta, Fergusson synonymized 10 of Cameron's nominal species under only three valid species.Seven species were synonymized with A. macrophadna after the revision of the type material; only A. fi licornis remains as a valid synonymy, the other six species here being re-assigned as valid or as synonyms of other Cameron species.The synonymy of A. mullensis with A. brevis has been studied in detail within the revision of the "brevis group" (Ferrer-Suay et al. 2012d).According to these authors, A. mullensis is considered as valid species.Only two of the synonymies established by Fergusson are now considered valid (apart from A. fi licornis synonymized with A. macrophadna): the synonymy of A. curvicornis with A. victrix and the synonymy of A. megaptera with A. castanea.
A key to identify the Alloxysta species present in Great Britain is given below.The type material of A. tscheki and A. ullrichi has not yet been studied, so they have been excluded from the key.