TRABAJOS CIENTÍFICOS

Egg parasitoids of Megamelus spp. (Hemiptera: Delphacidae) in Argentina tentativa

Parasitoides oófagos de Megamelus spp. (Hemiptera: Delphacidae) en la Argentina

Triapitsyn, Serguei V.^*, Alejandro J. Sosa^** and M. Cristina Hernández^**

^* Entomology Research Museum, Department of Entomology, University of California, Riverside, California, 92521, USA; e-mail: serguei.triapitsyn@ucr.edu
^** USDA-ARS South American Biological Control Laboratory, General Simón Bolívar 1559 (B1686), Hurlingham, Buenos Aires, Argentina: e-mail: alejsosa@speedy.com.ar, crisher@speedy.com.ar

ABSTRACT. Egg parasitoids (Hymenoptera: Eulophidae, Mymaridae, and Platygastridae) of Megamelus spp. (Hemiptera: Delphacidae) in Argentina are reviewed and keyed. Four new species are described: Anagrus (Anagrus) empanadus Triapitsyn, sp. nov. (Mymaridae, parasitoid of M. scutellaris Berg feeding on water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach, Aprostocetus (Ootetrastichus) riverplaticus Triapitsyn, sp. nov. (Eulophidae: Tetrastichinae, parasitoid of M. bellicus Marino de Remes Lenicov & Sosa), A. (Ootetrastichus) yerbamatei Triapitsyn, sp. nov. (parasitoid of M. bellicus, M. scutellaris and Megamelus sp.), all from Buenos Aires Province (A. (Ootetrastichus) yerbamatei also occurs in Formosa Province), and Parascelio sabcli Triapitsyn, sp. nov. (Platygastridae: Scelioninae, parasitoid of M. scutellaris in Formosa, the host association is tentative). Other known egg parasitoids of Megamelus spp. in Argentina include Kalopolynema (Kalopolynema) poema Triapitsyn & Berezovskiy (Mymaridae, parasitoid of M. scutellaris in Buenos Aires), and also Cremastobaeus atratus Loiácono & Mulvani (Platygastridae: Scelioninae, parasitoid of M. scutellaris in Formosa, the host association is tentative).

KEY WORDS. Delphacidae; Megamelus; Eulophidae; Mymaridae; Platygastridae.

RESUMEN. Se revisaron los parasitoides oófagos (Hymenoptera: Eulophidae, Mymaridae, y Platygastridae) de Megamelus spp. (Hemiptera: Delphacidae) de la Argentina, y se presenta una clave para su identificación. Se describen cuatro especies nuevas: Anagrus (Anagrus) empanadus Triapitsyn, sp. nov. (Mymaridae, parasitoide de M. scutellaris Berg que se alimenta de camalote, Eichhornia crassipes (Martius) Solms-Laubach; Aprostocetus (Ootetrastichus) riverplaticus Triapitsyn, sp. nov. (Eulophidae: Tetrastichinae, parasitoide de M. bellicus Marino de Remes Lenicov & Sosa); A. (Ootetrastichus) yerbamatei Triapitsyn, sp. nov. (parasitoide de M. bellicus, M. scutellaris y Megamelus sp.), todos de la provincia de Buenos Aires (A. (Ootetrastichus) yerbamatei también se encuentra en Formosa); y Parascelio sabcli Triapitsyn, sp. nov. (Platygastridae: Scelioninae, parasitoide de M. scutellaris en Formosa, la asociación con el huésped es tentativa). Se incluyen otros parasitoides oófagos conocidos de Megamelus spp. en la Argentina, tales como Kalopolynema (Kalopolynema) poema Triapitsyn & Berezovskiy (Mymaridae, parasitoide de M. scutellaris en Buenos Aires) y también Cremastobaeus atratus Loiácono & Mulvani (Platygastridae: Scelioninae, parasitoide de M. scutellaris en Formosa, la asociación con el huésped es tentativa).

PALABRAS CLAVE. Delphacidae; Megamelus; Eulophidae; Mymaridae; Platygastridae.

Recibido: 14-XII-2009;
Aceptado: 8-VII-2010

INTRODUCTION

Five species of the planthopper genus Megamelus Fieber (Hemiptera: Delphacidae) are known from South America, these were recently reviewed by Sosa et al. (2007b). They are frequently associated with aquatic plants, particularly the Pontederiaceae. Megamelus scutellaris Berg is considered a candidate for biocontrol of water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach, an invasive aquatic weed that clogs waterways, lakes, and channels in several countries beyond its native range (Sosa et al., 2004, 2005, 2007a, 2007b).
There are few records of egg parasitoids of Megamelus spp. in South America: Kalopolynema (Kalopolynema) poema Triapitsyn & Berezovskiy (Mymaridae) was reported from eggs of M. scutellaris on water hyacinth (Triapitsyn & Berezovskiy, 2002; Sosa et al., 2004, 2005), and Aprostocetus (Ootetrastichus) sp. from eggs of M. bellicus Marino de Remes Lenicov & Sosa (Mariani et al., 2007; Sosa et al., 2007b), both in Buenos Aires Province, Argentina. The latter is described here as A. (Ootetrastichus) riverplaticus Triapitsyn, sp. nov. Extralimital records include Kalopolynema (Kalopolynema) ema (Schauff & Grissell) in Florida (USA) on M. davisi Van Duzee (Triapitsyn & Berezovskiy, 2002), and Anagrus incarnatus Haliday (Mymaridae) in Wales (UK) on Megamelus notulus (Germar) (Whalley, 1956).
Megamelus scutellaris has been recently approved for release in Florida, thus a study of its egg parasitoid fauna in the native range was a necessity. In the course of this study, a number of both internal and internal/external egg parasitoids from three families of Hymenoptera (Eulophidae, Mymaridae, and Platygastridae) were discovered in Argentina, and these are keyed and reviewed herein.

MATERIAL AND METHODS

Most of the specimens were reared from the delphacid (Megamelus spp.) eggs, stored in ethanol, then dried using a critical point drier and point-mounted; selected specimens were dissected and slide-mounted in Canada balsam. The collections from Formosa Province were made by incubating (in the laboratory) the petioles of water hyacinth in opaque bottles with a translucent vial in the cap; the emerging parasitoids (if any) were collected daily.
Terms for morphological features follow Gibson (1997); we also use the abbreviation F for an antennal funicle (or flagellar in males of Mymaridae) segment. Unless indicated otherwise, measurements are given in micrometers (µm) as length or, where appropriate (e.g. for the wings), as length: width ratios.
Abbreviations for depositories of specimens are as follows: CNCI, Canadian National Collection of Insects, Ottawa, Ontario, Canada; MLPA, Museo de La Plata, La Plata, Buenos Aires, Argentina; UCRC, Entomology Research Museum, University of California, Riverside, California, USA; USNM, National Museum of Natural History, Washington, DC, USA.
The first author is solely responsible for most of the text; the second and the third authors provided the reared material for this study and contributed to the introduction and description of the collecting methods.

RESULTS

Taxonomy

Key to egg parasitoids of Megamelus spp. in Argentina

1. Forewing with venation short, extending at most to about 0.3x length of wing ............................................................................... 2
1´. Forewing with venation longer, extending at least to about 0.5x length of wing ........................................................ 3

2. Forewing at least 9.8x as long as wide, with only one, median, row of setae on disc (Fig. 21) ............................. Anagrus (Anagrus) empanadus Triapitsyn, sp. nov.
2´. Forewing about 7.3x as long as wide, with disc densely setose beyond venation (Fig. 25) ............ Kalopolynema (Kalopolynema) poema Triapitsyn & Berezovskiy

3. Antenna (excluding 3 or 4 anelli) 7- or 9-segmented; body smooth .....................4
3´. Antenna 12-segmented (anelli absent, F1 and F2 may be almost fused); body with reticulate sculpture ............................. 7

4. Antenna (excluding 4 anelli) 7-segmented, with scape not expanded (female) ...................................................................5
4´. Antenna (excluding 3 anelli) 9-segmented, with scape notably expanded (male) ...................................................... 6

5. Head mostly brown; midlobe of mesoscutum with 1 pair of setae............... Aprostocetus (Ootetrastichus) riverplaticus Triapitsyn, sp. nov.
5´. Head mostly yellow and light brown; midlobe of mesoscutum with 2 pairs of setae.................... Aprostocetus (Ootetrastichus) yerbamatei Triapitsyn, sp. nov.

6. Scape about 2.0x as long as wide....................................... Aprostocetus (Ootetrastichus) riverplaticus Triapitsyn, sp. nov.
6´ Scape about 2.9x as long as wide......................... Aprostocetus (Ootetrastichus) yerbamatei Triapitsyn, sp. nov.

7. Forewing with postmarginal vein present and longer than stigmal vein (Fig. 28) [female antenna with F1 and F2 almost fused and clava 4-segmented (Fig. 26)]................................................. Cremastobaeus atratus Loiácono & Mulvani
7´. Forewing with postmarginal vein absent (Fig. 32) [female antenna with F1 and F2 not fused and clava 5-segmented (Fig. 30)] ................. Parascelio sabcli Triapitsyn, sp. nov.

Eulophidae: Tetrastichinae

Aprostocetus (Ootetrastichus) riverplaticus Triapitsyn, sp. nov. (Figs 1-7)

Figs. 1-4. Aprostocetus (Ootetrastichus) riverplaticus sp. nov., female (holotype): 1, antenna; 2, mesosoma; 3, metasoma; 4, forewing.

Figs. 5-7. Aprostocetus (Ootetrastichus) riverplaticus sp. nov., male (paratype): 5, antenna; 6, genitalia; 7, forewing.

Aprostocetus (Ootetrastichus) sp.: Mariani et al., 2007: 189-190, 195 (information on the host and egg parasitism); Sosa et al., 2007b: 801, 803 (host information, biology).

Description. Female (holotype and paratypes). Body length 1650-2245 µm (dry-mounted paratypes). Head mostly brown except eyes and ocelli dirty pink; mesonotum greenish with bright metallic sheen, mesopleura mostly shining brown, tegula bright yellow; two basal gastral segments mostly yellow, remainder of gaster brown; scape, sometimes pedicel partially, and anelli yellowish, remainder of antennal segments a little darker (light brown); legs mostly yellow or yellowish brown except metacoxa shining brown and all apical tarsomeres brown.
Antenna (Fig. 1) with scape minus short radicle about 4.6x as long as wide and almost smooth; funicle (excluding 4 anelli, second anellus very short) 3-segmented, F1 the longest funicle segment, slightly longer than pedicel, F2 about as long as F3; clava 2-segmented, apical claval segment with a spicula and about 1.8x length of basal claval segment; funicle and claval segments with long hairs and each with at least 2 hair-like longitudinal sensilla. Mesosoma (Fig. 2) with pronotum entire, with more or less conspicuous sculpture; mesoscutum and scutellum faintly longitudinally striate, midlobe of mesoscutum with 1 pair of setae, scutellum with 2 pairs of setae, scutellar placoid sensilla about in the middle of scutellum. Metanotum and propodeum with inconspicuous sculpture, almost smooth.
Wings. Forewing (Fig. 4) 3.3-3.4x as long as wide; venation extending to about 0.6x length of wing, disc almost hyaline, mostly bare behind base of submarginal vein and densely setose elsewhere; the longest marginal seta 0.23-0.32x greatest width of disc. Hind wing 10.4-10.8x as long as wide; disc hyaline, bare behind base of venation and densely setose elsewhere; the longest marginal seta 1.2-1.4x greatest width of disc.
Metasoma (Fig. 3) with gaster elongate (particularly the apical gastral tergum), notably longer than mesosoma. Ovipositor occupying almost entire length of gaster, a little exserted beyond gastral apex; ovipositor length: metatibia length ratio 2.9-3.1:1.
Measurements (µm) of the holotype. Body: 1906; head: 271; mesosoma: 492; gaster: 1156; ovipositor: 1057. Antenna: scape: 155; pedicel: 74; F1: 79; F2: 67; F3: 67; clava: 157. Forewing: 1236:366; longest marginal seta: 118. Hind wing: 1045:97; longest marginal seta: 136.
Male (paratypes). Body length 1024-1321 µm (dry-mounted paratypes). Similar to female except for the normal sexually dimorphic features such as color, antenna, and genitalia, as follows. Head mostly yellow except eyes and ocelli dirty pink and area between posterior ocelli brown; pronotum brown dorsally, rest of metanotum shining brown with greenish metallic tinge; basal gastral segments yellow, apical segments brown; scape yellow to light brown, pedicel and anelli light brown, remainder of antennal segments slightly darker (brownish); legs mostly yellow except all apical tarsomeres brown. Antenna (Fig. 5) with scape about 2.0x as long as wide; funicle (excluding 3 anelli) 4-segmented, F1-F4 more or less subequal in length; clava 3-segmented, apical segment with a spicula; funicle and claval segments with long hairs and each with at least 2 hairlike longitudinal sensilla. Forewing (Fig. 7) about 3.2x as long as wide, the longest marginal seta about 0.27x greatest forewing width; hind wing about 9.4x as long as wide; discs of forewing and hind wing hyaline. Genitalia (Fig. 6) typical for the subgenus, digitus with a spine.

Diagnosis. In addition to the characters mentioned in the keys above and below, female of A. (Ootetrastichus) riverplaticus sp. nov. differs from that of A. (Ootetrastichus) yerbamatei sp. nov. in having a relatively wider forewing (3.3-3.4x as long as wide) with relatively shorter marginal setae (the longest marginal seta is 0.23-0.32x greatest width of the disc) whereas in A. (Ootetrastichus) yerbamatei the female forewing is 3.6-3.8x as long as wide and the longest marginal seta is 0.4-0.5x greatest width of the disc. The male of (Ootetrastichus) riverplaticus differs from that of A. (Ootetrastichus) yerbamatei in also having a relatively wider forewing (about 3.2x as long as wide) with relatively shorter marginal setae (the longest marginal seta is about 0.27x greatest width of the disc) whereas in A. (Ootetrastichus) yerbamatei the male forewing is about 4.0x as long as wide and the longest marginal seta is about 0.5x greatest width of the disc.
The females of A. (Ootetrastichus) riverplaticus and A. (Ootetrastichus) yerbamatei differ from that of A. (Ootetrastichus) infulatus (De Santis), the only species of the subgenus Ootetrastichus Perkins of the genus Aprostocetus Westwood that was previously described from Argentina (De Santis, 1957), in having the antennal flagellum with 4 anelli and a relatively longer ovipositor, as indicated in the key below. In A. (Ootetrastichus) infulatus, flagellum of the female antenna (Fig. 15) has 3 anelli (Luft Albarracin & Triapitsyn, 2007) and the ovipositor (Fig. 16) is notably shorter (the ovipositor length:metatibia length ratio is 1.5:1 in the holotype). The longest marginal seta on the forewing (Fig. 17) of the holotype female of A. (Ootetrastichus) infulatus is 0.27-0.28x maximum forewing width.

Figs. 15-17. Aprostocetus (Ootetrastichus) infulatus (De Santis), female (holotype): 15, antenna; 16, mesosoma and metasoma; 17, forewing.

The only other two species of the subgenus A. (Ootetrastichus) registered for the Neotropical region are the little known A. (Ootetrastichus) coxalis (Howard) (Grenada) and A. (Ootetrastichus) cupreus (Ashmead) (Grenada and Saint Vincent and the Grenadines) (Ashmead, 1894; Howard, 1897; De Santis, 1979; LaSalle & Schauff, 1992). Female head and mesosoma are mostly dark brown dorsally with a dark green metallic sheen in A. (Ootetrastichus) cupreus, and its apical gastral tergum is notably less elongate than in A. (Ootetrastichus) riverplaticus or A. (Ootetrastichus) yerbamatei. Because identification of the Neotropical species of A. (Ootetrastichus) is currently very problematic (prior to this study there were no keys available to separate them), a partial key is provided here (A. (Ootetrastichus) coxalis is excluded because the original description of its holotype, which was not available to us, is poor).

Key to the Neotropical species of Aprostocetus (Ootetrastichus) (females)

1. Ovipositor length:metatibia length ratio about 1.5:1 .................................................................A. (O.) infulatus (De Santis)
1´. Ovipositor length:metatibia length ratio at least 1.8:1 .....................................2

2. Head mostly brown or dark brown with or without dark green metallic sheen .................................................................... 3
2´. Head mostly yellow and light brown ......... A. (O.) yerbamatei Triapitsyn, sp. nov.

3. Gaster with two basal terga mostly yellow ................................................................ A. (O.) riverplaticus Triapitsyn, sp. nov.
3´. Gaster with two basal terga brown .................................... A. (O.) cupreus (Ashmead)

Etymology. The species is named after La Plata River (Río de la Plata, sometimes rendered River Plate in British English) in which basin it occurs.

Host. Megamelus bellicus Remes Lenicov & Sosa. Mariani et al. (2007) reported a 25.1% egg parasitism of this host in Argentina by A. (Ootetrastichus) riverplaticus [as Aprostocetus (Ootetrastichus) sp.], which is an internal/external egg parasitoid: the eulophid larvae develop within the host's egg and once emerged, they consume the other eggs in the scar (Sosa et al., 2007b), i.e. acting as egg predators. Its possible ability to attack also eggs of M. scutellaris Berg has yet to be demonstrated.

Type material. Holotype female [MLPA] on slide labeled: "ARGENTINA: Buenos Aires, Hurlingham, USDA-ARS South American Biol. Control Lab., 20.v.2005, A. Sosa & J. Dorado. Egg predator of Megamelus sp. (bellicus ms name of A. Sosa) colony on Pontederia cordata. Mounted at UCR/ERM by V. V. Berezovskiy 2005 in Canada balsam". Paratypes: ARGENTINA, Buenos Aires: Hurlingham, USDA-ARS South American Biological Control Laboratory: 22.i.2003, S. V. Triapitsyn, M. C. Hernández (from eggs of Megamelus sp. [later described as M. bellicus Remes Lenicov & Sosa (Sosa et al., 2007b)] on water hyacinth) [2 females, 4 males on points, UCRC]; 23.i.2003, M. C. Hernández, S. V. Triapitsyn (yellow pan traps in an artificial pond with water hyacinth infested with colonies of Megamelus scutellaris Berg and Megamelus sp. (later described as M. bellicus) [8 females, 3 males on points, UCRC, 1 male on point, MLPA, and 1 female, 1 male on slides, UCRC]; 20.v.2005, A. J. Sosa, J. Dorado ("egg predator" of Megamelus sp. [later described as M. bellicus] colony on Pontederia cordata) [9 females on cards, CNCI (1), MLPA (2), UCRC (5), USNM (1), 1 male on card, UCRC]. "Summer 2005", A. J. Sosa, J. Dorado ("egg predator" of Megamelus sp. [later described as M. bellicus]) [3 males on cards, UCRC].

Comments. Although some authors recently regarded Ootetrastichus as a valid genus separate from Aprostocetus (Kostjukov, 2004; Yegorenkova et al., 2007), we treat all these species in the subgenus Aprostocetus (Ootetrastichus) to ensure stability in this difficult group, until the status of Ootetrastichus is clarified based on a rigorous study of its species worldwide, and its relationships with other subgenera of Aprostocetus as well as other genera of Tetrastichinae are better understood.
The holotype of A. (Ootetrastichus) infulatus [in MLPA] was examined, it is poorly mounted (the body is fragmented) on slide labeled: 1. "Ootetrastichus infulatus Det. De Santis HOLOTIPO 1913/1 MUSEO DE LA PLATA", 2. "PUNTA LARA (Pcia. Buenos Aires") Col: De Santis II/1955 ♀". Female of this species was redescribed, and male newly described, by Luft Albarracin & Triapitsyn (2007), who also indicated Chlorottetix fraterculus (Berg), Dalbulus maidis (DeLong & Wolcott), Exitianus obscurinervis (Stål), Syncharina punctatissima (Signoret) (Cicadellidae), and Peregrinus maidis (Ashmead) (Delphacidae) as its hosts in Tucumán Province, Argentina.
One female (lacking both antennae) and one male paralectotypes of A. (Ootetrastichus) cupreus [both in USNM] were also examined, they were designated by LaSalle & Schauff (1992) and are labeled as follows: 1. "Sea Level.", 2. "Windward side St. Vincent, W. I. H. H. Smith", 3. "Tetrastichodes cupreus Ashm ♀ Type", 4. [red] "Cotype No. 2480 U.S.N.M.", 5. [blue] "Paralectotype Aprostocetus cupreus LaSalle + Schauff 1992" (female glued to a short pin inserted in a small card); and 1. "St. Vincent, W. I. H. H. Smith 241", 2. "Tetrastichodes cupreus Ash ♂ Type", 3. [red] "Cotype No. 2480 U.S.N.M.", 4. [blue] "Paralectotype Aprostocetus cupreus LaSalle + Schauff 1992" (male on a point).

Aprostocetus (Ootetrastichus) yerbamatei Triapitsyn, sp. nov. (Figs 8-14)

Figs. 8-11. Aprostocetus (Ootetrastichus) yerbamatei sp. nov., female (holotype): 8, antenna; 9, mesosoma; 10, metasoma; 11, forewing.

Description. Female (holotype and paratypes). Body length 1288-1300 µm (dry-mounted paratypes) or 1304-1636 µm (slide-mounted paratype and holotype, respectively). Head mostly yellow and light brown except eyes and ocelli dirty pink; mesosoma and metasoma dorsally mostly brownish (brown to dark brown with some greenish metallic sheen) except two basal gastral terga partially yellowish to light brown, tegula bright yellow; scape and anelli light brown, remainder of antennal segments brown; legs mostly yellowish except metacoxa and all apical tarsomeres darker (brownish).
Antenna (Fig. 8) with scape minus short radicle 4.4-4.6x as long as wide and almost smooth; funicle (excluding 4 anelli, second anellus very short) 3-segmented, F1 the longest funicle segment, a little longer than pedicel and notably longer than F2 or F3; clava 2-segmented, apical claval segment with a spicula and 1.8-2.2x length of basal claval segment; funicle and claval segments with long hairs and each with at least 2 hairlike longitudinal sensilla.
Mesosoma (Fig. 9) with pronotum entire, with more or less conspicuous sculpture; mesoscutum and scutellum faintly longitudinally striate, midlobe of mesoscutum and scutellum each with 2 pairs of setae, scutellar placoid sensilla close to posterior margin of scutellum. Metanotum and propodeum with inconspicuous sculpture, almost smooth.
Wings. Forewing (Fig. 11) 3.6-3.8x as long as wide; venation extending to about 0.6x length of wing, disc almost hyaline, mostly bare behind base of submarginal vein and densely setose elsewhere; the longest marginal seta 0.4-0.5x greatest width of disc. Hind wing 10.7-13.0x as long as wide; disc hyaline, bare behind base of venation and densely setose elsewhere; the longest marginal seta 1.4-1.9x greatest width of disc.
Metasoma (Fig. 10) with gaster elongate (particularly the apical gastral tergum), notably longer than mesosoma. Ovipositor occupying almost entire length of gaster, slightly exserted beyond gastral apex; ovipositor length:metatibia length ratio 2.7 - 2.9:1.
Measurements (µm) of the holotype. Body: 1636; head: 197; mesosoma: 418; gaster: 984; ovipositor: 935. Antenna: scape: 148; pedicel: 70; F1: 77; F2: 58; F3: 57; clava: 151. Forewing: 1113:308; longest marginal seta: 127. Hind wing: 910:85; longest marginal seta: 115.
Male (paratypes). Body length 1023 µm (dry-mounted paratype). Similar to female except for the normal sexually dimorphic features such as color, antenna, and genitalia, as follows. Head yellow except eyes and ocelli dirty pink; mesosoma and metasoma dorsally mostly grayish-dark brown with some metallic sheen except dorsellum a little lighter and two basal gastral terga yellow; scape and anelli pale, remainder of antennal segments slightly darker (light brown); legs mostly yellowish except pro-and mesotibiae apically and all apical tarsomeres darker (brownish). Antenna (Fig. 12) with scape about 2.9x as long as wide; funicle (excluding 3 anelli) 4-segmented, F1, F3 and F4 subequal in length, F2 slightly longer; clava 3-segmented, apical segment with a spicula; funicle and claval segments with long hairs and each with at least 2 hairlike longitudinal sensilla (except only 1 such sensillum on F1). Forewing (Fig. 13) about 4.0x as long as wide, the longest marginal seta about 0.5x greatest forewing width; hind wing about 12.0x as long as wide; discs of forewing and hind wing hyaline. Genitalia (Fig. 14) typical for the subgenus.

Figs. 12-14. Aprostocetus (Ootetrastichus) yerbamatei sp. nov., male (paratype): 12, antenna; 13, forewing; 14, genitalia.

Diagnosis. In addition to the distinguishing characters mentioned in the keys above, also see the diagnosis of A. (Ootetrastichus) riverplaticus sp. nov.

Etymology. The specific name refers to "yerba mate" (Ilex paraguariensis A. Saint-Hilaire), from which mate, first author's favorite drink in Argentina, is prepared.

Hosts. Megamelus bellicus Marino de Remes Lenicov & Sosa, M. scutellaris Berg, and Megamelus sp.

Type material. Holotype female [MLPA] on slide labeled: "ARGENTINA: Buenos Aires, Otamendi, 5.vii.2005, A. Sosa and J. Dorado. Egg predator of Megamelus scutellaris Berg on water hyacinth, Eichhornia crassipes. Mounted at UCR/ERM by V. V. Berezovskiy 2005 in Canada balsam". The type locality is Ingeniero Otamendi. Paratypes: ARGENTINA, Buenos Aires: Ingeniero Otamendi, 5.vii.2005, A. J. Sosa, J. Dorado (from eggs of M. scutellaris on water hyacinth) [1 male on card and 1 male on slide, UCRC]. "Summer 2005", A. J. Sosa, J. Dorado ("egg predator" of Megamelus sp. [later described as M. bellicus]) [3 females on cards, MLPA, UCRC, USNM, and 1 female on slide, UCRC].

Other material examined. ARGENTINA, Formosa: Herradura, "Laguna del Vivero" (an unnamed old meander of Río Paraguay near a nursery), 26°29'27''S 58°18'17''W, 61 m: 23.xi.2004, G. J. Cabrera, M. C. Hernández (emerged from petioles of water hyacinth infested with eggs of Taosa sp. (Dictyopharidae) and likely also of Megamelus sp.) [1 female, 1 male, UCRC]; 18.ii.2008, G. J. Cabrera, M. C. Hernández (emerged from petioles of water hyacinth infested with eggs of Megamelus sp. and Taosa (Cuernavaca) longula Marino de Remes Lenicov (Hemiptera: Dictyopharidae)) [3 females, UCRC]. Palo Santo, 9.i.2002, H. A. Cordo, M. C. Hernández (from petiole of water hyacinth with eggs of M. scutellaris) [1 female, 2 males, UCRC].

Mymaridae

Anagrus (Anagrus) empanadus Triapitsyn, sp. nov. (Figs 18-23)

Figs. 18-21. Anagrus (Anagrus) empanadus sp. nov., female: 18, antenna (paratype); 19, mesosoma (holotype); 20, metasoma (holotype); 21, forewing (holotype).

Description. Female (holotype and paratypes). Body length 594-693 µm (drymounted specimens) or 836-873 µm (slidemounted specimens). Face and vertex yellow except trabeculae and stemmaticum dark brown; scape and pedicel light brown, flagellum brown; pronotum pale, mesoscutum brown, anterior scutellum light brown, posterior scutellum lemon yellow, propodeum yellow except brown medially; legs mostly light brown; median and apical gastral terga yellow, remainder of gastral terga brown, ovipositor sheaths light brown.
Head about as wide as mesosoma.
Antenna (Fig. 18) with scape 3.0-3.4x as long as wide, with cross-ridges, a little shorter than clava; pedicel much longer than F1 (the shortest funicle segment); F2, F6, and often F4 the longest funicle segments (F6 sometimes slightly longer than F2 and F4), F3 and F5 slightly shorter (F5 sometimes almost as long as F4); F1-F3 and F5 without longitudinal sensilla, F4 with 1 longitudinal sensillum, and F6 with 2 such sensilla; clava 2.7-2.8x as long as wide (in lateral view), with 5 longitudinal sensilla.
Mesosoma (Fig. 19) about 0.5x as long as metasoma. Mesoscutum with a pair of short, weak adnotaular setae.
Forewing (Fig. 21) a little shorter than body, 10.1-10.7x as long as wide; disc slightly, inconspicuously infumate, with an incomplete median row of setae and a few additional setae in the middle; the longest marginal seta about 3.3x maximum wing width. Lengths of distal and proximal macrochaetae in ratio 3.2-3.4:1. Hind wing 29-32x as long as wide, disc with a row of setae along each margin; the longest marginal seta 7.2-7.5x maximum wing width.
Metasoma (Fig. 20). Ovipositor long, anteriorly usually overlapping mesophragma and posteriorly exserted beyond apex of gaster by 0.33-0.36x own length (ratio of total ovipositor length to length of its exserted part 2.7-2.8:1). External plate of ovipositor with 2 setae. Ovipositor length: protibia length ratio about 4.4:1.
Measurements (µm) of the holotype. Body: 836; head: 141; mesosoma: 246; metasoma: 449; ovipositor: 670. Antenna: scape: 94; pedicel: 42; F1: 18; F2: 55; F3: 46; F4: 52; F5: 48; F6: 55; clava: 106. Forewing: 652:61; longest marginal seta: 203. Hind wing: 615:21; longest marginal seta: 152.
Male (paratypes). Body length 528-561 µm (dry-mounted specimens). Similar to female except for the coloration and normal sexually dimorphic features such as antenna and genitalia, as follows. Color notably darker than in female: body mostly brown except posterior scutellum pale. Antenna (Fig. 22) with scape plus radicle about 2.8x as long as wide. Forewing about 9.8x as long as wide, a little wider than in female. Genitalia (Fig. 23) similar in shape and structure to those of the Neotropical species A. (Anagrus) amazonensis Triapitsyn, Querino & Feitosa, A. (Anagrus) brasiliensis Triapitsyn, A. (Anagrus) lineolus Triapitsyn, and A. (Anagrus) urichi Pickles (Triapitsyn, 1997, 2000, 2002; Triapitsyn et al., 2008).

Figs. 22, 23. Anagrus (Anagrus) empanadus sp. nov., male (paratype): 22, antenna; 23, genitalia.

Diagnosis. Member of the incarnatus species group of the nominate subgenus Anagrus (Anagrus Haliday), as defined by Chiappini et al. (1996). In the keys to the Argentinean and Neotropical species of Anagrus Haliday by Triapitsyn (2000, 2002), respectively, A. (Anagrus) empanadus sp. nov. would key to the same couplet with A. (Anagrus) lineolus, to which it is most similar. The female of A. (Anagrus) empanadus differs from that of A. (Anagrus) lineolus in lacking a longitudinal sensillum on F5 of the antenna and also in having a much longer ovipositor, which is exserted beyond apex of the gaster by 0.33-0.36x own length (the ovipositor length: protibia length ratio is about 4.4:1). In A. (Anagrus) lineolus, which is known from Argentina, Brazil, Mexico, Peru, and Florida, USA (Triapitsyn, 2002), the ovipositor is exserted beyond apex of the gaster by at most 0.11x own length (the ovipositor length: protibia length ratio is 1.9-2.1:1) (Triapitsyn, 2000). Anagrus (Anagrus) empanadus is also similar to the recently described A. (Anagrus) amazonensis from Brazil, whose female has a longitudinal sensillum on F5 of the antenna and also a much shorter ovipositor, which is exserted beyond apex of the gaster by at most 0.07x own length (the ovipositor length: protibia length ratio is 2.0-2.1:1) (Triapitsyn et al., 2008).

Etymology. The specific name refers to "empanada(s)", first author's favorite food in Argentina.

Host. Megamelus scutellaris Berg.

Type material. Holotype female [MLPA] on slide labeled: "ARGENTINA: Buenos Aires, Otamendi, 5.vii.2005, A. Sosa and J. Dorado. Ex eggs of Megamelus scutellaris Berg on water hyacinth (Eichhornia crassipes). Mounted at UCR/ERM by V. V. Berezovskiy 2005 in Canada balsam". The type locality is Ingeniero Otamendi. Paratypes: ARGENTINA, Buenos Aires: Ingeniero Otamendi, 5.vii.2005, A. J. Sosa, J. Dorado (from eggs of M. scutellaris on water hyacinth) [10 females on cards, CNCI (1), MLPA (2), UCRC (6), USNM (1), 2 males on cards, MLPA, UCRC, and 1 male on slide, UCRC]. Near Ingeniero Otamendi, Río Paraná de las Palmas shore, 34º10'52.7''S 58º52'12.8''W, 6 m, 23.i.2003, S. V. Triapitsyn, M. C. Hernández, total sweeping [1 female on slide, UCRC].

Kalopolynema (Kalopolynema) poema Triapitsyn & Berezovskiy (Figs 24, 25)

Figs. 24, 25. Kalopolynema (Kalopolynema) poema Triapitsyn & Berezovskiy, female (paratype): 24, antenna; 25, forewing.

Kalopolynema (Kalopolynema) poema Triapitsyn & Berezovskiy, 2002: 614-616.
Kalopolynema poema: Sosa et al., 2004: 274 (host information); Sosa et al., 2005: 71 (host information).

Comments. See Triapitsyn & Berezovskiy (2002) for the detailed description and diagnosis of K. (Kalopolynema) poema, originally described from two female specimens collected at the USDA-ARS South American Biological Control Laboratory in Hurlingham, Buenos Aires, Argentina. The female antenna (Fig. 24) and forewing (Fig. 25) are illustrated here to facilitate its recognition. The male of this species is unknown.

Host. Megamelus scutellaris Berg (Triapitsyn & Berezovskiy, 2002; Sosa et al., 2004, 2005).

Material examined. ARGENTINA, Buenos Aires: near Ingeniero Otamendi, Río Paraná de las Palmas shore, 34º10'52.7''S 58º52'12.8''W, 6 m, 23.i.2003, S. V. Triapitsyn, M. C. Hernández [1 female, UCRC]. Tigre, 34°23'50''S 58°34'32''W, 5 m, G. A. Logarzo: 9-16.xi.2005 [1 female, UCRC]; 2–11.ii.2006 [2 females, MLPA, UCRC].

Platygastridae: Scelioninae

Cremastobaeus atratus Loiácono & Mulvani (Figs 26-29)

Figs. 26-29. Cremastobaeus atratus Loiácono & Mulvani (Palo Santo, Formosa, Argentina): 26, female antenna; 27, female mesosoma and metasoma; 28, female forewing; 29, male antenna.

Cremastobaeus atratus Loiácono & Mulvani, 1987: 16-18, 20 (measurements), 23-24 (illustrations); Johnson, 1992: 365 (catalog).

Comments. Species of the almost cosmopolitan genus Cremastobaeus Ashmead were reviewed by Loiácono & Mulvani (1987) mainly based on the material collected by A. A. Ogloblin in Loreto, Misiones, Argentina. This is the first record of C. atratus outside of its type locality in Loreto. To facilitate recognition of this species, here we provide illustrations of the female antenna (Fig. 26), mesosoma and metasoma (Fig. 27), and forewing (Fig. 28) as well as of the male antenna (Fig. 29).

Host. Megamelus scutellaris Berg. However, this host association is tentative due to the collecting method described in "Material and methods"; if confirmed, that would be the first known host record for the genus besides the possible host association with Gryllidae (Orthoptera) (Masner & Hanson, 2006).

Material examined. ARGENTINA, Formosa, Palo Santo, 9.i.2002, H. A. Cordo, M. C. Hernández (from petiole of water hyacinth with eggs of M. scutellaris) [2 females, 3 males, UCRC].

Parascelio sabcli Triapitsyn, sp. nov. (Figs 30-32)

Figs. 30-32. Parascelio sabcli sp. nov., female (holotype): 30, antenna; 31, mesosoma (posterior part only) and metasoma; 32, fore- and hind wings.

Description. Female (holotype and paratypes). Body length 2410–2520 µm. Body mostly dark brown except fourth gastral tergite and sternite almost entirely light brown, remainder of gaster contrastingly brown to dark brown. Scape, pedicel, and funicle light brown to brown, clava dark brown; legs light brown except tarsi a little darker (brown).
Head with punctate-reticulate sculpture, with short, weak hairs.
Antenna (Fig. 30) with scape about 4.5x as long as wide and smooth; F1 almost as long as pedicel and the longest funicle segment, F3-F5 a little wider than F1 or F2; clava about as long as funicle, with basal four segments wider than long and the apical segment a little longer than wide.
Mesosoma notably sculptured, with pronotum short; scutellum with dense pubescence (setae longer than on mesoscutum). Metanotum medially with a strong spine (Fig. 31).
Wings (Fig. 32). Forewing 3.5-3.6x as long as wide; disc almost hyaline (at most with a very slight brownish tinge), densely setose; the longest marginal seta about 0.13x greatest width of disc. Hind wing about 6.6x as long as wide; disc almost hyaline (at most with a very slight brownish tinge), densely setose; the longest marginal seta 0.34-0.35x greatest width of disc.
Legs. Coxae smooth.
Metasoma (Fig. 31) with strong sculpture on three basal tergites. Ovipositor occupying almost entire length of gaster, a little exserted beyond gastral apex (by 0.03–0.12x own length); ovipositor length:metatibia length ratio about 2.6:1.
Measurements (µm) of the holotype. Body: 2520; head: 363; mesosoma: 677; gaster: 1480; ovipositor: 1433. Antenna: scape: 230; pedicel: 100; F1: 97; F2: 51; F3: 48; F4: 40; F5: 40; clava: 279. Forewing: 1660:467; longest marginal seta: 62. Hind wing: 1298:197; longest marginal seta: 68. Male. Unknown.

Diagnosis. The female of P. sabcli sp. nov. differs from those of the previously described congeneric species by the color of the gaster, as indicated in the key below.
The generic diagnoses of the Neotropical genus Parascelio Dodd were given by Masner (1976) and Austin & Field (1997). The genus has not been previously recorded from Argentina. Prior to this study there were no keys available to separate the three described species.

Etymology. The species is named after the USDA-ARS South American Biological Control Laboratory (SABCL).

Host. Megamelus scutellaris Berg. This host association is tentative due to the collecting method described in "Material and methods"; if confirmed, that would be the first known host record for the genus.

Type material. Holotype female [MLPA] on slide labeled: 1. "ARGENTINA: Formosa, Palo Santo, 9.i.2002, C. Hernández "Prs./ Megamelus sp.". Mounted at UCR/ERM by V. V. Berezovskiy 2008 in Canada balsam"; 2. "Parascelio Det. L. Masner, 2006". Paratypes: same data as the holotype [2 females on points, CNCI, UCRC]. The collectors were H. A. Cordo (in the field) and M. C. Hernández (in the laboratory), parasitoids emerged from petioles of water hyacinth infested with eggs of M. scutellaris.

Key to the species of Parascelio (females)

1. Body mostly orange-yellow ....................................................... P. ruber (Szabó)
1´. Body mostly dark brown or black ......................................................................... 2

2. Gaster entirely dark brown or black ..................................................................... 3
2´. Gaster with fourth gastral tergite and sternite almost entirely light brown, remainder of gaster contrastingly brown to dark brown ....... P. sabcli Triapitsyn, sp. nov.

3. F3 and F4 yellow ........................................................................ P. undulatus Dodd
3´. F3 and F4 brown ......................................................................... P. molnari (Szabó)

ACKNOWLEDGEMENTS

We thank Vladimir V. Berezovskiy (UCRC) for mounting the specimens; Lubomír Masner (CNCI) for the generic identifications of Parascelio sp. and Cremastobaeus sp.; Marta Loiácono (MLPA) for the identification of Cremastobaeus atratus and also for arranging a loan of the holotype of Aprostocetus (Ootetrastichus) infulatus; John La Salle (Australian National Collection of Insects, CSIRO Entomology, Canberra, Australian Capital Territory, Australia) for valuable comments on the status of Aprostocetus (Ootetrastichus) and help with the literature; Terry Nuhn (USNM) for the loan of type specimens of Aprostocetus (Ootetrastichus) cupreus; and Guillermo A. Logarzo (USDAARS South American Biological Control Laboratory, Hurlingham, Buenos Aires, Argentina) for collecting many interesting specimens of Mymaridae in Argentina. Jennifer Walker (UCRC) prepared some of the illustrations.

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