Cheiloneurus compressicornis Ashmead, 1894

Noyes, John Stuart, 2023, ENCYRTIDAE OF COSTA RICA (HYMENOPTERA: CHALCIDOIDEA), 4 Subfamily Encyrtinae: tribes Arrhenophagini, Habrolepidini, Cerapterocerini, Cheiloneurini, Trechnitini, Cercobelini, Polaszekiini, Protyndarichoidini, Gahaniellini and Syrphophagini (part), mainly primary parasitoids and hyperparasitoids of Coccoidea and Psylloidea (Hemiptera), Taxonomic Monographs on Neotropical Hymenoptera (Oxford, England) 2 (11), pp. 1-921 : 397-399

Cheiloneurus compressicornis Ashmead

(Figs 1011-1018; Hab. E 150,151)

Chrysopophagus compressicornis Ashmead, 1894:246 . Lectotype E (here designated), USA (Missouri), USNM, examined.

DIAGNOSIS. Female (length about 1.2-1.6mm): body mostly orange to pale orange-brown, generally with a weak metallic sheen; mesoscutum dark brown with a slightly coppery and brassy, metallic green sheen, propodeum dark brown, gaster dark brown mixed orange-brown, darker areas with a stronger metallic sheen; antenna (Fig. 1013, 1014) with scape pale orange; pedicel pale orange, sometimes slightly dusky; funicle with F1 orange-brown, rest of flagellum dark brown; mesoscutum with evenly distributed, moderately dense, silvery setae; fore and hind coxae white or pale yellow, mid coxa pale brown; legs mostly orange but with hind tibia dark brown, sometimes also hind femur; fore wing (Fig. 1017, 1018) mostly infuscate with basal cell almost completely hyaline, small area at apex of venation and area on opposite margin hyaline, apex narrowly hyaline; head (Fig. 1011, 1012) about 2.8-2.9X as wide as frontovertex, in facial view about 1.1-1.3X as long as broad, genae straight and converging, curved inwards near mouth; frontovertex with about 25 inconspicuous setae medially between anterior ocellus and scrobes; eye separated from scrobe by about 3X diameter of anterior ocellus, area between eye and scrobe with distinct sculpture, scrobes very shallow with rounded margins; interantennal prominence with about 30-35.inconspicuous setae and dorsally rounded; mandible tridentate; antenna (Fig. 1013, 1014) with scape about 6.3-8.0X as long as broad; flagellum slightly flattened, F1-F2 longer than broad, F3-F6 quadrate or transverse; head width at least slightly greater than length of funicle; linear sensilla on F2-F6, sometimes absent from F2; clava 3-segmented, about as long as F4-F6 combined, apex broadly rounded but sensory area extending a little more than 0.3X along clava so that clava is asymmetric in profile; mesoscutum with uniform, shallow, polygonally reticulate sculpture; scutellum with a distinct, apical tuft of setae; wings fully developed; fore wing (Figs 1013, 1014) about 2.8-3.2X as long as broad; parastigma strongly downcurved; costal cell dorsally naked, ventrally with a line of very fine setae that reaches about three-quarters to apex; area below proximal part of parastigma with a group of about 50 fine setae; apices of postmarginal and stigmal veins connected by a naked, hyaline line that hardly extends into disc (Fig. 1015); seta at apex of postmarginal vein about 0.5X as long as marginal vein; mid tibial spur about as long as basitarsus; propodeum with about 5-20 setae adjacent to spiracle not extending down side; gaster without “gland-like” structures on Gt1 or Gt5; syntergum about 0.8X as long as mid tibia; ovipositor (Fig. 1016) about 4.4X gonostylus or about 1.4X as long as mid tibia; gonostylus about 0.9X as long as mid tibial spur; exserted part of ovipositor about 0.4-0.5X as long as mid tibial spur. Male (length 1.00- 1.36mm): generally very similar to female but for antenna and genitalia; colouration similar to that of female, although the scutellum and mesopleuron may be dark orange brown; frontovertex usually slightly dusky to pale brown and with a weak metallic green and coppery sheen in ocellar area; fore wing generally hyaline, but with an incomplete, infuscate band across wing from marginal vein; flagellum filamentous, funicle segments cylindrical, subequal in width, longer than broad and gradually becoming shorter distally, F1 nearly 5X as long as broad, F6 about 3X as long as broad, clava about 5X as long as broad, segments clothed in whorls of long setae, longest about 3X as long a diameter of segment.

DISTRIBUTION. USA (newly recorded from Arizona and Texas [new records]), Mexico and Costa Rica (new record) (see also Noyes, 1919).

HOSTS. Recorded as a hyperparasitoid, and possibly tertiary parasitoid, of various species of Chrysopa ( Neuroptera : Chrysopidae ) in association with encyrtid, perilampid and ichneumonid primary or hyperparasitoids (see Noyes, 2019). Recorded below from “brown lacewing” (probably Neuroptera : Hemerobiidae ), Chrysopa cocoon and pupa of Chrysoperla harrisi (Fitch) ( Neuroptera : Chrysopidae ) and in association with Phenacoccus cevalliae Cockerell and as a parasitoid of Phenacoccus solani Ferris ( Hemiptera : Pseudococcidae ). It is likely that the species is hyperparasitic on both mealybugs and their lacewing predators.

MATERIAL EXAMINED.

Type material. Syntypes of compressicornis : USA, 1E, Missouri “Miss”, “E”, “E Type No. 1465 U.S. N.M.” “Chrysopophaga compressicornis Ashm E ” “ USNM ENT 00802838 ”. This female is in good condition and is designated LECTOTYPE of compressicornis in the interests of nomenclatural stability ( USNM) .

Non type material. USA, 1E, California, Uplands, ex Chrysopa cocoon, 28.vii.1919 (H.M. Armitage) “ Chrysopophagus compressicornis Ashm.Timb. det.”; 1E, California, San Marino, ex brown lacewing, i.1927 (A.I. Basinger, Coll), “Compared with Syntype of C. compressicornis A.” “ Cheiloneurus compressicornis Ashm ”; 1E, Arizona, Phoenix, Phenacoccus cevalliae, Lot No. 43-8395, 16.vi.1943, B.M. 1982-101, “ Cheiloneurus compressicornis Ashm. det Gahan”; 2E, 2G, Texas, Tom Green Co., San Angelo:Corp. of Eng., Prickly Pear Project, 1.xi.1983, 26.x.1983 and 10.x,1984 (Gilreath-Hackler Coll.); 2E, 1G, Texas, Coleman Co., Coleman: Horne Ranch, 18.x.1984 and 16.ix.1984 (Gilreath-Hackler Coll.) (one specimen mounted with mummies of Pseudococcidae ); 1G, South Carolina, Greensboro, E.V. 63, collected on cotton, 5.ix.1913, Hunter No 3414, “BM 1982-101”; 1G, South Carolina, Batesburg, E.V. 39 (45), Par. iss 8.ix.1913, Hunter No 3414, “BM 1982-101”, 1E, South Carolina, Batesburg, E.V. 28? (73), Par. iss 10.ix.1913, Hunter No 3414, “BM 1982-101”, “ Cheiloneurus compressicornis Ash. det Crawford”; 7E, 1G, South Carolina, Pickens Co., Clemson, ex pupa Chrysoperla harrisi (Fitch) on wild cherry, CR-2, 24.vi.1985 (J.R. Brushwein). MEXICO, 1E, Nuevo León, Monterrey, Huinala, ex Phenacoccus solani on root of Parthenium , v.1983 (F.D. Bennett). COSTA RICA, 1E, Guanacaste, Santa Rosa NP, Bosq. Hum. 9-0, 16.xi-7.xii.1985 (Janzen, Gauld); 1E, Guanacaste, Santa Rosa NP, H 4C, 27.ix-18.x.1986 (D. Janzen, I.D. Gauld); 1E, Guanacaste, PN Santa Rosa , 10°51’N 85°37’W, 300m, 24.ii.2009 (J.S. Noyes); 1E, Guanacaste, PN Palo Verde, Sector Catalina, LN 257400 400000, 230m, #44947, 8.i-8.ii.2000 (I. Jiménez); 1E, Guanacaste, Santa Cruz, PN Marino Las Baulas, LN 258040 332690, 0m, #59488, 16.viii.2000 (Y. Cardenas); 1E, Alajuela, San Ramon BS, 700m, viii-ix.1995 (P. Hanson); 1E, San José, Ciudad Colon, 800m, ii.1990 (L. Fournier). 1E, Cartago, Turrialba, CATIE, v.1994 (P. Hanson); 1E, Puntarenas, Manuel Antonio NP, 8-14.xii.1987 (Greniere, Bertrand); 1E, Puntarenas, Pen. Osa , Puerto Jimenez, 10m, ii-iii.1993 (P. Hanson). Material in NHMUK, MZUCR and CNC.

COMMENTS. The head of the lectotype of compressicornis is badly collapsed which makes comparison difficult, but I am confident that it is the same species as the material listed above. The species is very close to, and may be the same as, Cheiloneurus dubius , described from males “parasitic in all probability, on a species of Lecanium ” ( Howard, 1885) associated with pines. As compressicornis is well known as a hyperparasitoid of immature Chrysopidae via encyrtid primary parasitoids and the taxonomy of males is difficult I am not formally treating the two as synonymous pending a more detailed study of males of this genus.

The material examined shows some notable variation in the relative length of the head (hardly longer than high to nearly 1.3X as high as wide), corresponding relative length of gena and the relative length of F 1 in relation to pedicel length (slightly shorter to slightly longer than pedicel), relative density of darker setae below the distal part of the parastigma (see Figs 1017, 1018), as well as other variation noted under diagnosis. Costa Rican specimens differ slightly from North American specimens in having the mesoscutum slightly less metallic green and with a more coppery and brassy sheen. North American specimens are also a little larger, being up to 1.86mm in length and generally have F1 relatively slightly longer in relation to the pedicel and the fore wing varying from 2.8-3.0X as long as broad. Some North American specimens also have the subhyaline apical area of the forewing slightly larger than in Costa Rican specimens.

Cheiloneurus compressicornis might be very similar to the fully winged form of repola , if it exists. Apart from the differences highlighted in the key and above, compressicornis differs from repola in having the sensory area of the clava extending a little more than 0.3X along the ventral surface of the clava and the ovipositor is about 4.4X as long as the gonostylus. In repola the sensory part of the clava is at the apex only, extending less than 0.2X along the ventral surface, and the ovipositor is about 3.4X as long as the gonostylus.

Cheiloneurus nankingensis Li & Xu , recently described from Jiangsu province, China and reared as a hyperparasitoid of Phenacoccus solenopsis Tinsley ( Hemiptera : Pseudococcidae ) via its primary parasitoid Aenasius arizonensis (Girault) ( Hymenoptera : Encyrtidae ) ( Li et al, 2020) is extremely close to compressicornis and may be synonymous. It is likely that both the host and primary parasitoid of nankingensis originated in North America and that all three have been accidentally introduced from there into China. However, I hesitate to formally treat nankingensis and compressicornis as synonymous because the male of nankingensis appears to have completely hyaline fore wings, whereas males of compressicornis have a distinct infuscate area below the apex of the venation.