Calosota acron (Walker)

Gary A. P., Gibson, 2010, Calosota Curtis (Hymenoptera, Chalcidoidea, Eupelmidae) - review of the New World and European fauna including revision of species from the West Indies and Central and North America, ZooKeys 55, pp. 1-75 : 9-13

Calosota acron (Walker) Figs 112284252586774

Eupelmus Acron Walker 1848: 129, 219. Type data: England. Lectotype ♀ (BMNH, type no. 5.1619; not examined), designated by Graham 1969: 91.

Trigonoderus contractus Walker 1872: 85-86. Type data: England. Holotype ♀ (BMNH, type no. 5.3328; not examined), by monotypy. Synonymy by Graham 1969: 91.

Calosota anguinalis Ruschka 1921: 251. Type data: Austria, Thüringen. Syntypes, ♀ (NHMW; not examined). Synonymy by Bouček 1968: 236.

Calosota acron ; Bouček 1968: 236.

Calosota pseudotsugae Burks 1973: 27-29. Holotype ♀ (USNM, type no. 72481; examined), by original designation. syn. n.

Description.

FEMALE (Figs 28, 42). Length about 2.8-4.7 mm. Color. Head (Fig. 1) with variably large green spot below anterior ocellus and variably extensively and conspicuously green along inner orbit except parascrobal region always with dark band at about dorsal limit of interantennal region, usually partly green within scrobal depression and on interantennal region under different angles of light, and at least obscurely green (sometimes greenish with coppery luster under some angles of light) on lower face, but otherwise dark from level of posterior margin of eyes to about dorsal level of interantennal region, and parascrobal region usually dark along scrobal depression; posterior surface of head dark to sometimes greenish-blue under different angles of light except more distinctly bluish-purple in variably complete ∩-shaped band along outer orbit and occiput. Maxillary and labial palpi dark. Antenna dark except scape variably extensively yellow basally (usually with about basal quarter to third yellow), and dark part of scape and pedicel sometimes with green luster under some angles of light. Tegula yellow. Mesoscutum (Fig. 28) variably extensively greenish-blue to bluish-purple laterally, but parapsidal line, anteroadmedian line or region between anteroadmedian line and notaulus, and dorsomedially anterior to base of scutellum coppery or greenish with coppery luster; scutellar-axillar complex mostly similar in color to mesoscutum medially except frenal area bluish-purple. Acropleuron (Fig. 52) variably bluish-green except microsculptured region or diffuse region extending obliquely from microsculptured region toward tegula coppery. Legs (Fig. 42) with femur and tibia of front leg variably extensively dark, but trochanter and trochantellus at least distinctly lighter in color and knee, apex of tibia, and tarsus yellow; middle leg often entirely yellow beyond coxa but sometimes with similar color pattern as front leg except femur and tibia much lighter brownish-yellow; hind leg usually yellow beyond coxa though sometimes up to about basal two-thirds of femur brownish or dark with very slight metallic luster. Fore wing hyaline; setae uniformly brown. Gaster (Fig. 42) mostly brown dorsally but syntergum and gaster laterally more bluish-green, similar to mesosoma laterally.

Structure/setation. Head in dorsal view about 1.9 –2× as wide as long, with IOD about 0.4 –0.47× head width, OOL slightly more than half, LOL subequal to, and POL almost twice MPOD; in frontal view about 1.1 –1.2× as wide as high, with ventral margin to about middle of torulus at level of lower orbits; malar space about 0.55 –0.7× height of eye. Head (Figs 1, 67) with frontovertex finely meshlike coriaceous, the sculpture at least obscurely extended ventromedially within scrobal depression between smooth and shiny scrobes; parascrobal region finely coriaceous dorsally to somewhat more vertically coriaceous-alutaceous ventrally; clypeal region microcoriaceous, but interantennal region and paraclypeal region coriaceous-reticulate except smoother narrowly along lower inner orbit. Head with white setae except for bare scrobal depression. Antenna (Fig. 28) with scape about 3.6 –4.2× as long as wide; pedicel about 2 –2.3× as long as wide; flagellum clavate with length of flagellum + pedicle about 1.4 × head width; combined length of fu1 + fu2 slightly greater than (larger specimens) to slightly less than (smaller specimens) length of pedicel; fu1 obviously longer than wide except in small specimens, but less than 1.5 × as long as wide; subsequent funiculars oblong basally to only slightly longer than wide or subquadrate apically with fu2 about 1.5 –2× and fu8 at most about 1.2 × as long as wide; clava often slightly collapsed (compressed), but about as long as apical three funiculars. Mesoscutum (Figs 12, 28, 74) meshlike-reticulate with somewhat larger flat-bottomed reticulations medially, and with comparatively inconspicuous white setae; usually with quite deep and distinct notauli on inclined anterior surface and with quite distinct parapsidal lines, but with only obscure anteroadmedian lines on anterior inclined surface indicated by longitudinal region of slightly different color or sculpture. Axillae (Figs 28, 74) large, almost equilateral-triangular in smaller specimens, and separated by only about 1 –1.5× own width. Scutellum low convex, about 1.3 –1.4× as long as wide; similarly reticulate as mesoscutum laterally (Fig. 74); with inconspicuous white setae. Mesopleuron (Fig. 52) with exposed, setose lower mesepimeron; acropleuron variably extensively reticulate anteriorly, becoming more coriaceous to obliquely coriaceous-alutaceous anterior to oblique microsculptured region and very finely, longitudinally to slightly obliquely alutaceous-aciculate posteriorly. Fore wing (Fig. 58) with cc: mv: stv: pmv about 30-35: 21-25: 10: 17-20; basal cell entirely setose; cubital area usually quite extensively setose behind mediocubital fold and/or apically, and closed by setae along posterior margin over about apical half; disc basally with oblique bare band separated from basal fold, parastigma and base of marginal vein, and with short region of mediocubital fold bare just beyond basal fold. Metacoxa setose along dorsal and ventral margins and outer surface usually extensively though less densely setose basally. Propodeum with callus setose to posterior margin; bare anteriorly between spiracle and foramen. Gaster (Figs 28, 42) about 1.6 –2× as long as mesosoma; more or less uniformly covered with inconspicuous white, hairlike setae; penultimate tergum with posterior margin extending to or slightly beyond level of cerci; syntergum about 1 –1.8× as long as transcercal width, uniformly convex, and about 0.8 –0.9× as long as penultimate tergum.

MALE (based on single regional specimen). Similar to female except as follows. Antenna with scape more robust, only about 3 × as long as wide; fu1 + fu2 about 1.4 × length of pedicel, fu1 about 2 × as long as wide, fu8 about 1.2 × as long as wide, and clava only slightly longer than combined length of apical two funiculars. Fore wing with cc: mv: stv: pmv = 34: 27: 10: 18.

Biology.

Burks (1973) stated that the type material of Calosota pseudotsugae was reared from downed Pseudotsuga menziesii (coast Douglas-fir) along with seven other insect species and suggested that it probably was reared from Pseudohylesinus nebulosus (LeConte) ( Coleoptera : Curculionidae : Scolytinae ). Deyrup (1975) later determined that it was a hyperparasitoid of Pseudohylesinus nebulosus through Spathius sequoiae Ashmead ( Hymenoptera : Braconidae ), one of the species originally reared with the type material. Two other females were also reared in North America through Spathius sequoiae from the alder bark beetle, Alniphagus aspericollis (LeConte) ( Coleoptera : Curculionidae : Scolytinae ). In addition to Pseudotsuga menziesii , other regional tree associates are Alnus ruba (red alder), Tsuga heterophylla (western hemlock), and Thuja sp.

Noyes (2003) does not list any associates for Calosota acron , but Graham (1969) reported rearing females in Oxford, England, from "old trellis-work infested with Anobium striatum (Olivier)" ( Coleoptera : Anobiidae ) (2♀ BMNH) and based on label data another observed female from Oxford (BMNH) was reared as a hyperparasitoid of Tetropium sp. ( Coleoptera : Cerambycidae ) through Xylonomus [= Xorides Latreille] ( Hymenoptera : Ichneumonidae ). Fusu (2009) also reared Calosota acron from dry branches of Carpinus (hornbeam) and Fagus (beech) together with Xestobium sp., and Xestobium plumbeum (Illiger) and Anobium fulvicorne Sturm ( Coleoptera : Anobiidae ), respectively. The host records indicate Calosota acron is at least a facultative hyperparasitoid.

Regional material examined

(Map 1). CANADA. British Columbia: BC Hydro Site, 49°09.3374'N; 122°52.2023'W, 22.VII.08, from Thuja , N. Furness (1♀ CNC). Stanley Park, 3c Pipeline Drive, 49°18.46314'N; 123°08.52413'W, 26.VI.08, 6.VII.08, from Tsuga heterophylla , N. Furness (7♀ CNC, CNC Photo 2009-13, 2009-14, 2009-15, CNC SEM 2009-33, 2009-34). Surrey, Dogwood RV Site, 49°12.5989'N; 122°48.3367'W, 6.VI.08, from Thuja plicata , N. Furness (1♀ CNC). USA. Oregon: Benton Co., Mary’s Peak (nr Corvallis), 15.VIII.84, M.E. Schauff & E.E. Grissell, roadside meadow (1♀ USNM). Washington: King Co., Cedar Falls, 12.III.75, M.A. Deyrup, from Spathius sequoiae from Alniphagus aspericollis in Alnus ruba (2♀ CNC, CNC Photo 2009-50). Thurston Co., Maytown, Jct. Rt. 121 & US 5, 24.II.72, M.A. Deyrup, reared from Pseudotsugae menziesii in insectary, 6, 7, 8, 9, 12 (CNC Photo 2009-48) Apr. (♀ holotype, ♂ allotype and 4♀ paratypes of Calosota pseudotsugae ).

Distribution.

Noyes (2003) listed Calosota acron from several countries in Western Europe; I saw females from Croatia (CNC), England (BMNH), France (CNC Photo 2009-33, USNM) and Sweden (BMNH). The species has only been rarely collected in North America in the lower Fraser Valley in British Columbia and Washington and Oregon (Map 1). This restricted distribution and its host biology strongly indicates Calosota acron is not a naturally occurring Holarctic species but likely was introduced accidentally in wood products relatively recently through the port of Vancouver (Canada) or perhaps Seattle (USA).

Recognition.

Although I did not examine the lectotype of Calosota acron , my concept of this name and new synonymy of Calosota pseudotsugae is based on the keys of Graham (1969) and Askew and Nieves-Aldrey (2006), and comparison of North American specimens with authoritatively identified specimens of Calosota acron from Europe in the BMNH. Some females seen from Europe are up to about 7.5 mm, their much larger size suggesting the possibility of different, larger hosts. The larger females have all the legs entirely yellow beyond the coxae, can have up to about the basal half of the scape yellow, typically have a more distinct coppery region on the mesoscutum extending posteriorly from each parapsidal line (Fig. 12), and the syntergum is somewhat more elongate-slender, up to about twice as long as the transcercal width, as indicated by Graham (1969). The larger females also have much more obvious anteroadmedian lines (Fig. 12), which appears to be at least partly correlated with specimen size in Calosota . However, I hereby synonymize the name Calosota pseudotsugae under Calosota acron syn. n. because North American and European specimens do not differ substantially in morphology. Askew and Nieves-Aldrey (2006) suggested that Calosota ariasi Bolívar y Pieltain (1929) might be a synonym of Calosota acron , but this European name more likely is a junior synonym of Calosota aestivalis if not a valid species (see under Calosota aestivalis ).

Calosota acron is recognized primarily by the presence of an oblique fore wing linea calva (Fig. 58). Calosota albipalpus sometimes also has a variably developed oblique bare band, though typically there is then also a narrow bare region along the basal fold. Regardless, Calosota acron is readily differentiated from Calosota albipalpus by several features, including dark palpi and an exposed and at least sparsely setose lower mesepimeron (Fig. 52). Askew and Nieves-Aldrey (2006, fig. 14) noted that the outer surface of the metacoxa is mostly setose, but this is variable and smaller specimens typically have the outer surface more extensively bare mediolongitudinally (Fig. 52).