World species of the genus Platyscelio Kieffer (Hymenoptera: Platygastridae)

Abstract The genus Platyscelio Kieffer (Hymenoptera: Platygastridae, Scelioninae) is a widespread group in the Old World, found from West Africa to northern Queensland, Australia. The species concepts are revised and a key to world species is presented. The genus is comprised of 6 species, including 2 known species which are redescribed: Platyscelio africanus Risbec (Benin, Cameroon, Central African Republic, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Kenya, Mozambique, Nigeria, Sierra Leone, South Africa, Tanzania, Togo, Uganda, Yemen, Zimbabwe); and Platyscelio pulchricornis Kieffer (Australia, Bangladesh, China, India, Indonesia, Japan, Malaysia, Papua New Guinea, Philippines, Solomon Islands, Taiwan, Thailand, Vanuatu, Vietnam). Five species-group names are considered to be junior synonyms of Platyscelio pulchricornis: Platyscelio abnormis Crawford syn. n., Platyscelio dunensis Mukerjee syn. n., Platyscelio mirabilis Dodd syn. n., Platyscelio punctatus Kieffer syn. n., and Platyscelio wilcoxi Fullaway. The following species are hypothesized and described as new taxa: Platyscelio arcuatus Taekul & Johnson, sp. n. (Western Australia); Platyscelio mysterium Taekul & Johnson, sp. n. (Zimbabwe, Botswana, South Africa); Platyscelio mzantsi Taekul & Johnson, sp. n. (South Africa); and Platyscelio striga Taekul & Johnson, sp. n. (Western Australia).


Introduction
Species of Platyscelio (Hymenoptera: Platygastroidea, Platygastridae) are morphologically unique among the known Scelioninae by a number of characters, most distinctively the extremely fl at body, the broad hypostomal bridge, and the absence of a netrion. Th e genus was originally described by Kieff er (1905) with a single species, Platyscelio pulchricornis from Dilo in British New Guinea. To date, six species-group taxa have been described. Five species are recorded in Asia, Australia and Oceania: P. pulchricornis Kieff er, P. abnormis Crawford, P. dunensis Mukerjee, P. mirabilis Dodd, and P. punctatus Kieff er. Only one species is known from Africa, P. africanus Risbec, described from Cameroon. Platyscelio was classifi ed within the subfamily Scelioninae of the family Scelionidae by Kieff er (1905), but was not placed in any tribe until Kozlov (1970) erected the monobasic tribe Platyscelionini. Sharkey (2007) has subsequently combined the families Scelionidae and Platygastridae under the single name Platygastridae, but he did not address the status of their respective subfamilies or tribes. Kozlov (1970) asserted that Platyscelionini is close to the tribe Scelionini, but did not substantiate this hypothesis. Masner (1976) noted that the genus is distant from other Scelioninae due to its lack of a netrion, the greatly reduced palpi, and the expansion of the female antennal scape into a fl at, almost triangular piece armed laterally with a sharp spine. Austin and Field (1997) examined the ovipositor structure and concluded that Platyscelio possesses a Scelio-type system. Th ey also commented on two unusual features of the genus: the second gonocoxae are developed as broad membranous plates, and the lateral apodemes of the sixth metasomal sternum in the female protrude proximally past the telescopic tube at rest. Platyscelio was not included as a taxon in the most comprehensive attempt to infer relationships within the Platygastroidea published to date (Murphy et al. 2007).
Agyen-Sampong conducted all his observations in West Africa, mostly Sierra Leone. Th ese data, albeit fragmentary, suggest that Conocephalus eggs are at least among the hosts of Platyscelio spp, across the range of the genus from West Africa to Australasia. Kozlov (1970) asserted that the host of the genus must be the fl attened eggs of Phaneropterinae (Orthoptera: Tettigoniidae), and also suggested that the strongly fl attened body of Platyscelio may indicate that the species are phoretic in habit.
In more than a century since its original description, Platyscelio has never been comprehensively reviewed or revised. Our goal of this paper is to present a taxonomic revision of the world species of the genus Platyscelio, as well as to expand the biogeographic data associated with these species. Th e taxonomic history of the genus is summarized and existing concepts are reviewed. Four new species are proposed, two from Western Australia, two from southern Africa.
In the Material Examined the numbers prefi xed with "OSUC" are unique identifi ers for the individual specimens. Th e label data for all specimens have been georeferenced and recorded in the Hymenoptera On-Line database, and details on the data associated with these specimens can be accessed at the following link, purl.oclc.org/ NET/hymenoptera/hol, and entering the identifi er in the form. Note the space between the acronym and the number.
Data associated with the genus Platyscelio can be accessed at http://hol.osu.edu/ index.html?id=543. Species descriptions were generated using a database application, vSysLab 24 , designed to facilitate the production of a taxon by character data matrix, and to integrate those data with the existing taxonomic and specimen-level database. Data may be exported in both text format and as input fi les for other applications. Th e text output for descriptions is in the format of "Character: Character state (s). Images and measurements were made using AutoMontage and Cartograph extended-focus software, using JVC KY-F75U digital camera, Leica Z16 APOA microscope, and 1X objectve lens. Images are achived at Morphbank and in Specimage 25 , the image database at Th e Ohio State University.
In this article we have followed the precedent of Pyle et al. (2008) and Johnson et al. (2008) in the implementation of biodiversity informatics standards within a taxonomic publication. Th e electronic version of the paper contains hyperlinks to external resources. Insofar as possible the external information conforms to standards developed and maintained through the organization Biodiversity Information Standards 26 (Taxonomic Database Working Group). All new species have been prospectively registered with Zoobank (Polaszek et al. 2005), and other taxonomic names, where appropriate, have been retrospectively registered. Th e external hyperlinks are explicitly cited in the endnotes so that users of the printed version of this article have access to the same resources. Life sciences identifi ers, LSIDs, may be resolved at the specifi ed URLs or at lsid.tdwg.org.
Th is work is conducted as part of the Platygastroidea Planetary Biodiversity Inventory. Th e contributions of the authors are as follows: C. Taekul Head: Head in dorsal view strongly transverse; vertex laterad of posterior ocellus smooth or with few faint striae, between posterior ocelli fi nely longitudinally striate; hyperoccipital carina present as fi ne ridge on vertex between compound eyes; occipital carina absent; posterior ocellus distinctly separated from inner orbit of compound eyes, OOL > diameter of ocellus; compound eye large, appearing glabrous; frons without depression, shallowly convex, with median longitudinal sulcus bifurcating dorsally near median ocellus and ventrally near toruli; interantennal process well-developed, narrow; torular triangle present; submedian carina sometimes present; orbital carina sometimes present; lower frons, including cheek, with weak fanlike striae arising from mandibular condyle; shortest distance on frons between eyes less than eye height; inner orbits weakly diverging ventrally; postclypeus strongly projecting above anteclypeus, subtriangular, anteclypeus short, longest medially, lateral corners not produced; malar sulcus present; gena variably expanded, smooth to longitudinally striate or with few faint striae; labrum hidden by clypeus; mandible short, apex tridentate, middle tooth distinctly shortest, teeth arranged transversely; maxillary palpus 2-segmented, all segments cylindrical; labial palpus 1-segmented, very short; antenna 12-merous in both sexes; radicle very broad, inserted into ventral apex of A1, nearly parallel to longitudinal axis of A1, with small lateral spine; A1 almost triangular and expanded outwardly into spine, particularly in female; A2 distinctly shorter than A3; gustatory sensilla on female antenna arranged in longitudinal pairs on apical antennomeres; clava laterally compressed, claval formula A12-A8: 1-2-2-2-1; male antenna with tyloid on A5.
Metasoma: Metasoma elongate, parallel-sided, strongly fl attened dorsoventrally; female with six visible terga and sterna, male with seven visible terga and sterna; second to fi fth segments equal in length, third and fourth widest, subequal to each other in size; submarginal ridge developed, defi ned by narrow laterotergites to form deep submarginal rim; sublateral carina well developed on tergites, rarely absent (P. striga); no spiracles visible; sculpture on T1-T4 variable; S1 not laterally compressed; felt fi eld absent.
Link to distribution map. 27 Th e genus Platyscelio is a widespread group throughout the Old World tropics, extending from West Africa to Queensland. Four species have relatively restricted distributions: P. arcuatus and P. striga (Western Australia), P. mysterium (Zimbabwe, Botswana, South Africa), and P. mzantsi (South Africa). Two species are widespread: P. africanus occurs in the Afrotropical realm from Senegal east to Yemen and south to South Africa; and P. pulchricornis is found in India and Southeast Asia east to Papua New Guinea and eastern Australia.

1.
Striae within ocellar triangle sparse (fewer than 20); distance between anterior ocellus and posterior ocellar line in frontal view greater than or equal to 0.5× POL (Figs 17, 71)   Comments. Th is species is widespread in the Afrotropical realm, extending from east Africa to Yemen and south to the north of South Africa. Th e color of the female antenna is variable: the scape is yellow to light brown, but in some specimens is dark brown to black (OSUC 207985, 207972;Figs 7, 11). Th e color variability is also seen on the legs: coxae are dark brown to black, otherwise the legs are yellow throughout in most specimens, but in some the hind femur is dark brown (OSUC 207985, 207954, 207955 Description. General: Body length of male: 3.87 mm (n=1). Body length of female: 3.48-3.97 mm (n=3).
Head: Length between anterior ocellus and posterior ocellar line in frontal view: greater than or equal to 0.5 times POL. Striae within ocellar triangle: sparse (equal to or less than 20). Vertex sculpture between inner orbit and posterior ocellus: smooth or with few faint striae. Frontal sculpture between inner orbit and central keel: smooth. Submedial ventral area of head anterior to fossa: longitudinally striate throughout. Orbital carina: absent. Sculpture of malar region: longitudinally striate or with few faint striae.
Antenna: Color of female antenna: dark brown to black throughout. Female outer lateral apex of scape: sharply pointed. Claval shape: apical margin of A9-A11 concave, closely fi tting basal margin of following antennomere. Color of male antenna: dark brown to black throughout.
Head: Length between anterior ocellus and posterior ocellar line in frontal view: less than 0.5 times POL. Striae within ocellar triangle: dense (greater than 20). Vertex sculpture between inner orbit and posterior ocellus: densely striate. Frontal sculpture between inner orbit and central keel: longitudinally striate, striae extending through most of length of frons. Submedial ventral area of head anterior to fossa: smooth, fi nely longitudinally striate posteriorly. Orbital carina: present. Sculpture of malar region: longitudinally striate or with few faint striae.
Antenna: Color of female antenna: A1-A7 yellow to light brown, A8-A12 dark brown to black. Female outer lateral apex of scape: sharply pointed. Claval shape: apical margin of A9-A11 concave, closely fi tting basal margin of following antennomere. Color of male antenna: brown or dark brown to black throughout.
Mesosoma Diagnosis. Platyscelio mysterium is distinguished from other species by the presence of only a single lateral carina on the mesoscutum, the lack of a notaulus, and the presence of orbital carinae on the frons (Figs 21, 23).
Etymology. Th e epithet mysterium, Latin for mystery, refers to the interpretation of the mesoscutal carinae.
Link to distribution map. Comments. Some specimens show variability in the prominence of the sculpture between inner orbit and central keel on the frons. Description. General: Body length of male: 3.24-4.71 mm (n=20). Body length of female: 3.31-5.59 mm (n=20). Head: Length between anterior ocellus and posterior ocellar line in frontal view: less than 0.5 times POL. Striae within ocellar triangle: dense (greater than 20). Vertex sculpture between inner orbit and posterior ocellus: smooth or with few faint striae. Frontal sculpture between inner orbit and central keel: smooth. Submedial ventral area of head anterior to fossa: smooth, fi nely longitudinally striate posteri- orly. Orbital carina: absent. Sculpture of malar region: smooth, longitudinally striate or with few faint striae. Color of female antenna: dark brown to black throughout, A1-A7 yellow to light brown, A8-A12 dark brown to black, or A1-A7 brown, A8-A12 dark brown to black, in some antennae sequentially darker from scape to apex. Female outer lateral apex of scape: sharply pointed. Claval shape: apical margin of A9-A11 concave, closely fi tting basal margin of following antennomere. Color of male antenna: brown.

Platyscelio pulchricornis
Mesosoma: Sculpture on medial lobe of mesoscutum: longitudinally striate with elongate punctures. Setation of medial lobe of mesoscutum: moderately dense, even. Notaulus: present. Notaulus form: mesal and lateral margin arched. Length of notaulus: percurrent or nearly so, or abbreviated, clearly not reaching anterior margin of mesoscutum. Width of notaulus anteriorly: parallel-sided. Pilosity of notaulus: absent. Number of lateral carinae on mesoscutum: 0. Medial  Comments. Some specimens show variability in antenna and leg color. Because of the uniformity of the principal characters -notaulus form and length, interrupted posterior scutellar sulcus, and the propodeal sculpture -we consider these specimens to be conspecifi c with P. pulchricornis. Description. General: Body length of male: 3.05-3.22 mm (n=2). Body length of female: 2.89-3.40 mm (n=2).

Platyscelio striga
Head: Length between anterior ocellus and posterior ocellar line in frontal view: less than 0.5 times POL. Striae within ocellar triangle: dense (greater than 20). Vertex sculpture between inner orbit and posterior ocellus: smooth or with few faint striae. Frontal sculpture between inner orbit and central keel: with few (4-5) striae, striae limited to upper half of frons. Submedial ventral area of head anterior to fossa: longitudinally striate throughout. Orbital carina: absent. Sculpture of malar region: longitudinally striate or with few faint striae.
Antenna: Color of female antenna: A1-A7 brown, A8-A12 dark brown to black, in some antennae sequentially darker from scape to apex. Female outer lateral apex of scape: sharply pointed. Diagnosis. Platyscelio striga is unique in the genus in having two lateral carinae on the mesoscutum (Fig. 63), and no sublateral carinae on T2-T4 (Figs 61, 64).
Etymology. Th e epithet striga, Latin for swath, refers to the distinct striae of the frons.

Platyscelio mzantsi
Head: Length between anterior ocellus and posterior ocellar line in frontal view: greater than or equal to 0.5 times POL. Striae within ocellar triangle: sparse (equal to or less than 20). Vertex sculpture between inner orbit and posterior ocellus: smooth or with few faint striae. Frontal sculpture between inner orbit and central keel: smooth. Submedial ventral area of head anterior to fossa: longitudinally striate throughout. Orbital carina: absent. Sculpture of malar region: longitudinally striate or with few faint striae.
Antenna: Color of female antenna: dark brown to black throughout. Female outer lateral apex of scape: bluntly rounded. Claval shape: apical margin of A9-A11 concave, closely fi tting basal margin of following antennomere. Color of male antenna: dark brown to black throughout.
Diagnosis. Platyscelio mzantsi may be separated from other African species by the sparse striae within ocellar triangle (20 or fewer), the narrow metascutellum, and the presence of 4-6 foveae on the metanotum laterad of the metascutellum (Figs 71, 72). Some specimens have the sculpture on the submedian propodeal fi eld strongly eff aced.
Etymology. Th e epithet mzantsi, Xhosa for south, is a reference to the the collecting locality. Link