Redescription of Chrysoctonus and description of Chrysoctonoides (Hymenoptera, Mymaridae), a new genus from the Australian Region

Abstract Chrysoctonoides longisetosa Huber & Triapitsyn (Hymenoptera: Mymaridae), gen. n. and sp. n., is described from Australia. It is compared with the related genus Chrysoctonus, known from Africa and the New World. Myrmecomymar Yoshimoto, syn. n., is synonymized under Chrysoctonus Mathot and its type species is transferred to Chrysoctonus as Chrysoctonus masneri (Yoshimoto), comb. n.


Introduction
described a species based on numerous specimens of both sexes collected from a peat bog in Ontario, Canada, and placed it in his new genus Myrmecomymar. He was aware that the genus was fairly widespread in the Western Hemisphere, having recorded specimens representing undescribed species from USA, Ecuador, Trinidad, and Venezuela, but he described only the type species. He was unaware that Myrmecomymar had previously been described from Africa under a different name, Chrysoctonus Mathot (1966). Here, we describe a new genus from Australia related to Chrysoctonus and synonymize Yoshimoto's genus.

Methods
The type specimens and about 85 specimens of Myrmecomymar masneri Yoshimoto,30 unidentified specimens (several species) of the genus from Canada and USA, and 55 specimens from Central and South America were examined, from Belize and the Dominican Republic in the north to Uruguay in the south. The holotype of Chrysoctonus apterus Mathot and several additional specimens from central Africa were also examined. Abbreviations used are: fl =funicle segment (in female) or flagellar segment (in male), gt = gastral tergum, LOL = least ocellar length (i.e., shortest distance between anterior and a posterior ocellus), mps = multiporous plate sensillum, OOL = ocular-ocellar length (i.e., shortest distance between posterior ocellus and eye), POL = posterior ocellar length (i.e., shortest distance between posterior ocelli). The term "fenestra", used below in the descriptions, was defined and illustrated for Mymaridae in Huber 2012: 17 and figs 139 and 140, as well as in Huber 2013, fig. 33. In the former paper, Fig. 140 is mislabelled. The fenestra, or scutellar fenestra, is the same structure so the lower arrow and label on Fig. 140 should be ignored; the upper arrow indicates the correct structure. The following acronyms are used for institutions in which the specimens are deposited. vertex with many appressed, diverging setae medially surrounded by bare area; occiput separated from vertex by curved suture above foramen. Antenna with 4-8 funicle segments, the basal ones short (Figs 33,34). 36,37) with pronotum entire, from about half as long as to longer than the short, strongly transverse mesoscutum; notauli apparently absent; scutellum with frenum not de-Figures 7-12. Chrysoctonus sp., mesosoma (except 12); specimens from Florida. 7 female, dorsal 8 female, anterior (slightly ventral) 9 female, lateral 10 female, ventral 11 male, lateral 12 male gaster (apical two-thirds), lateral. Scale bars = 20 µm. marcated, about as long as or longer than mesoscutum; metanotum narrow, hidden under scutellum; propodeum flat, reticulate, with denticles medially; propodeal spiracle small, several times its diameter from anterior margin of propodeum. Metasoma 33,(38)(39)(40) with petiole tubular, about 1.5× as long as wide, strongly  reticulate; gaster with gt 1 the largest tergum, with lateral panels covering at least half of gaster, and with a cluster or row of setae anterolaterally; gt 2 the next largest tergum; cercal setae long. Gaster without spiracle on gt 6. Ovipositor slightly exserted beyond apex of gaster (Figs 18,19,(38)(39)(40). Male. Body length 425-760. Fully winged. Head (Figs 20-23) with normal eyes and ocelli. Flagellum 11-segmented (Figs 24,25), each segment equally wide with parallel sides and several rows of short setae, each much shorter than segment length. Mes-osoma (Figs 11,(28)(29)(30) with pronotum short, in dorsal view barely visible; propleura abutting medially along most of their length (Fig. 29); prosternum small, triangular; mesoscutum as long as scutellum, without notauli (Figs 25,50); scutellum with (Fig. 28) or without campaniform sensilla, and fenestra wide, occupying most of scutellum. Fore wing with venation more than half wing length (Figs 26,27); microtrichia unevenly distributed on wing surface; hind wing short and narrow. Metasoma (Fig. 31) with gt 1 the largest segment. Genitalia (Figs 30,32) with aedeagal apodeme at least as long as half length of gaster.
The greatest range in number of funicle segments of any genus of Mymaridae is found in Chrysoctonus species: one specimen from Panama had 4 segments and two from Costa Rica had 8 segments; the usual number appears to be 5 segments.
The only described species in Myrmecomymar is transferred here to Chrysoctonus as C. masneri (Yoshimoto), comb. n.
Hosts and habitat. Hosts are unknown. Specimens from the type locality were collected in August in pan traps placed near the base of trees in a forest normally flooded in spring and early summer (L. Masner, personal communication). Other specimens of the type species and other, undescribed, species were collected in Canada from a sedge pond, hollows and hummocks in a bog, peat bog, old forest, Carya grove, and spring flood debris. In the USA specimens have been collected from a hardwood forest, beaver swamp, oak forest, and forest hammock. In Central and South America and various Caribbean islands specimens were collected from wet cloud forest litter, forest litter, compost pile, forested creek, montane oak forest, cloud forest, rainforest, palm forest, and thicket forest, from about sea level to 2000m. The habitat types strongly suggest that females parasitize hosts found in moist soil or associated with water. The holotype of C. apterus and other African specimens were collected from forest litter.
Chrysoctonoides differs from Chrysoctonus, the most similar-looking genus, as follows. Female: mesoscutum and scutellum each medially much longer than pronotum (each about the same length in Chrysoctonus); median and lateral lobes of mesoscutum, and scutellum with strong setae (setae absent in Chrysoctonus); fenestra small, some-what triangular and occupying much less than half width of scutellum (fenestra large, oval, occupying most of scutellum in Chrysoctonus). Male: Flagellum with each segment somewhat irregular-shaped, often slightly wider medially and with at most only 1 mps and 4 setae, the setae much longer than segment length (each segment with straight edges and parallel-sided, with several mps and setae, the setae much shorter than segment length in Chrysoctonus). Both sexes: prosternum large, about as long as line of junction of propleura (small, much shorter than line of junction in Chrysoctonus).
Description. Female. Medium in length and wingless in the only included species. Head. Almost cuboidal, about 1.25× as wide as long and about 1.2× as wide as high; in lateral view projecting forward for about length of radicle beyond level of anterior margin of eye then, more ventrally, flat and receding to mouth (Figs 48,49,53). Preorbital sulcus clearly separated from eye, from apex of preorbital trabecula extending straight down side of face to just lateral to mouth opening. Face square. Subantennal sulci absent. Torulus almost touching transverse trabecula. Eye small (Figs 44,49,53), with about 12 ommatidia, in lateral view somewhat triangular, slightly longer than high. Malar space at least 1.3× eye height. Malar sulcus absent. Gena width in lateral view at level of mid-height of eye about 2.6× eye width, and gena merging smoothly but quite sharply with occiput. Vertex in lateral view slightly convex, horizontal, almost at right angle with face (separated from face by transverse trabecula), posteromedially separated from occiput by slightly curved carina. Ocelli absent (Figs 44, 54, 55). Occiput entire; foramen dorsal, almost at junction with vertex ( Fig. 55) so head pendulous (Figs 48,49,53). Labrum with 5 setae. Mandibles each with 3 teeth, crossing when closed. Antenna. Scape about 5.7× as long as wide, with radicle distinct, narrow, about 0.2× scape length; pedicel about 0.34× scape length, 2.0× as long but wider than fl 1 ; funicle 7-segmented (Figs 43, 49); clava unsegmented, about 0.4× funicle length. Mesosoma. About 1.7× as long as wide, 1.3× as long as high, and 0.7× wide as high. Pronotum in dorsal view (Figs 45,54,55) short, about 0.3× mesoscutum length, entire, and with a low transverse carina at anterior margin of collar. Pronotal spiracle level with anterior apex of notaulus. Propleura abutting medially, their line of junction much less than length of prosternum. Prosternum somewhat triangular, apparently divided posteriorly by median suture less than half prosternum length. Mesoscutum with straight, strongly diverging notauli. Transscutal articulation straight. Scutellum almost as long as mesoscutum (20: 23), without campaniform sensilla but with two setae in their position (Figs 45,55) and fenestra a small, somewhat triangular oval behind the setae. Axilla normal, triangular. Prepectus narrow, slightly wider dorsally than ventrally. Mesopleuron almost vertical, about 0.6× as long as high; the mesepimeron almost as wide as mesepisternum. Metanotum extremely narrow, without defined dorsellum. Propodeum in lateral view flat, strongly sloping, about 1.2× as long as scutellum, not clearly separated from metapleuron. Propodeal spiracle small, at extreme anterolateral corner of propodeum and about its diameter from metanotum. Wings. Apparently absent (extremely micropterous). Legs. Metacoxae (Fig. 61, fore leg) distinctly reticulate.
Male. Medium in length and fully winged (Fig. 56). Colour. Body fairly uniformly light brown, the gaster slightly darker in about apical half; legs beyond coxae and antenna slightly lighter than body. Head about 1.3× as wide as long and about 1.5× as wide as high. Eye large (Figs 56, 57), with about 75 ommatidia, in lateral view almost round, about as long as high. Malar space about 0.3× eye height. Gena in lateral view at level of top and bottom of eye about 0.5× eye width. Ocelli present, with LOL about 0.66× POL, and OOL about 1.0× POL. Antenna. Flagellum 11-segmented (Figs 56, 57, 66); scape 6.1× as long as wide, with radicle about 0.18× scape length and distinct; pedicel about 0.36× scape length and 1.25× as long as fl 1 ; flagellomeres each with several extremely long setae and some flagellomeres uneven in width, either slightly wider or slightly narrower medially. Mesosoma. About 1.8× as long as wide, 1.7× as long as high, and 1.3× wide as high. Scutellum about as long as mesoscutum (Fig. 60), with the usual campaniform sensilla submedially and also with two short, slender anterolateral setae; fenestra wide and occupying most of scutellum, with its margin anterior to the campaniform sensilla. Metanotum normal, with slightly defined rhomboidal dorsellum. Propodeum in lateral view flat, strongly sloping. Wings. Fully winged (Figs 56,  62). Fore wing about 4.6× as long as wide, with microtrichia not evenly covering wing surface. Venation about 0.6× wing length. Parastigma + stigmal vein about 1.8× length of submarginal vein. Hind wing normal; venation about 0.4× wing length. Legs. Calcar fringed internally with several setae (Fig. 64). Metasoma. Gaster about 1.5× as long as high. Genitalia (Fig. 61) with aedeagus extending well beyond parameres and apparently without aedeagal apodeme (this may have been broken off during dissection).

Chrysoctonoides longisetosa
Description. Female. Body length 570-675 (n=2). Colour. Yellow; brown are trabecula, sockets of setae on mesosoma, and, especially, propodeum, and gaster dor-  sally and laterally in about apical half but anterior to cerci. Head. Width 174 (n=1). Vertex with two pairs of fairly short setae, eye orbit dorsally with three long setae, one posteriorly and two anteriorly. Antenna. Fl 1 the shortest segment (Figs 43,49,58) and without mps, the remaining segments each with 1 mps; clava with 4 mps. Measurements (n=2 (Figs 45,50,55); scutellum with 2 long, diverging setae near transscutal articulation; axilla with 1 shorter seta; propodeum without carinae but with small tubercles medially and with reticulate sculpture laterally, with propodeal seta near posterolateral corner. Metasoma. Petiole strongly reticulate; gaster in dorsal view with anterior surface of gt 1 vertical and less than 0.1× length of gaster, in lateral view lateral panel of gt 1 covering more than 0.5 length of gaster; gt 2 dorsally covering over half gaster length and with 2 long dorsal setae; re-maining terga short; cercus with long setae, the longest almost 3× cercal length. Ovipositor slightly projecting beyond gastral apex.
Relationships. Chrysoctonoides and Chrysoctonus may be sister genera though there are still considerable structural differences between them, especially in the mesosoma. Features that suggest a sister group relationship are: females apterous whereas males macropterous, wing shape in males identical, with long venation, antennal (especially funicle) and gastral structure in females very similar. Mathot (1966) had suggested that Chrysoctonus had the greatest affinity with Ooctonus, but did not say why. We tentatively concur with that proposed relationship on the basis of the similar structure of the metasoma. Both have a tubular petiole and well-sclerotized (non-collapsing) gaster with large gt 1 and gt 2 . The presence of a group of several setae anterolaterally on gt 1 (Figs 14, 16) in Chrysoctonus, as in Ooctonus, is particularly striking. A large fenestra occupies most of the scutellum in males and females of Ooctonus but in Chrysoctonus and Chrysoctonoides only the male has a large fenestra whereas the females of both genera have an oval fenestra, in Chrysoctonoides relatively smaller than in Chrysoctonus, positioned posterior to the scutellar setae and almost as wide as the distance between them (Figs 45, 59). Chrysoctonoides females also lack the lateral cluster of setae on gt 1 .