Based on examination of morphological characters of specimens from throughout their ranges, Euaresta stelligera (Coquillett) is confirmed to be a distinct species from E. bellula (Snow). The diagnostic characters, distributions, and host plants of both species are discussed. New distribution records for E. aequalis (Loew) and E. tapetis (Coquillett) are also provided, and an error concerning the range of Valentibulla californica is noted

Norrbom, Allen L.

English

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INSECTA MUNDI, Vol. 16, No. 1-3, March-September, 2002  81 The status of Euaresta stelligera (Coquillett) (Diptera: Tephritidae) Allen L. Norrbom Systematic Entomology Laboratory, PSI Agriculture Research Service, U. S. Department of Agriculture c/o National Museum of Natural History Washington, DC 20560-0168, U.S.A. email: anorrbom@sel.barc.usda.gov Abstract. Based on examination of morphological characters of specimens from throughout their ranges, Euaresta stelligera (Coquillett) is confirmed to be a  distinct species from E.  bellula (Snow). The diagnostic characters,  distributions,  and host plants of both species are discussed.  New distribution records for E. aequalis (Loew) and E. tapetis (Coquillett) are also provided, and an error concerning the range of Valentibulla californica is noted. Key words: Euaresta bellula, stelligera,  aequalis,  tapetis,  Valentibulla calif  arnica, Ambrosia, taxonomy, host plants, distributions. Introduction Species of the genus Euaresta breed in rag-weeds, bursages, and cockleburs of the closely re-lated composite genera Ambrosia L., Xanthium L., andDicoria Torr. and Gray (Asteraceae: Helianthe-ae: Ambrosiinae) (Foote 1984, Goeden and Teerink 1993).  Because  some  of their host plants cause health problems (hayfever and other allergic reac-tions) and/or are agricultural weeds, various Euar-esta species have been investigated or introduced as biological control agents (Batra 1979). Euaresta stelligera (Coquillett, 1894), original-ly described as Trypeta (Euaresta)  stelligera, has been generally considered a synonym of Euaresta bellula Snow, 1894, since Quisenberry's (1950) re-vision ofthe U.S. species ofthis genus. On the other hand, Berlocher (1984)  presented electrophoretic data, based on single populations of E.  stelligera from Oregon and E. bellula from New Mexico, that suggest that there are two distinct species. He also listed several morphological differences between his two samples, but he did not investigate these characters in other populations. In the latest com-prehensive treatment of North American Euaresta, Foote et al. (1993) continued to treat E. stelligera as a  synonym of E.  bellula.  They noted Berlocher's work, but suggested  further investigation was need-ed to resolve the status of this complex. In a world catalog of Tephritidae, Norrbom et al. (1999) recog-nized E.  stelligera as a valid species, but without further explanation. This paper reports the results of a morphological investigation of additional spec-imens from throughout the ranges of these species. They support Berlocher's (1984) hypothesis that E. stelligera is a valid species, distinct from E. bellula. The diagnostic characters, distributions, and host plants of both species are discussed. Diagnosis. Berlocher (1984:  356) stated that his Oregon specimens of E.  stelligera had "a broader gena, darker markings on the femora, and a more elongate ovipositor tip than the New Mexico flies [E.  bellula]." He also stated that he "observed that the Oregon flies have dark markings on the postor-bital region,  in addition to the markings of the occiput seen in the New Mexico flies."  Based on examination  of  specimens from additional geograph-ic areas (a list of examined specimens will be posted on  the  SELISI  Diptera  web  site;  see  http:// www.sel.barc.usda.gov/Diptera/tephritilEuaresta/ Euaresta.htm), gena size and the microtrichia pat-tern of  the abdomen are consistent diagnostic char-acters for E.  bellula and stelligera. Leg color and aculeus tip shape are also useful characters, but I see little difference in head color. The following couplets are provided to replace couplet 6 of the key to U.S. and Canadian species of Euaresta of Foote et aL (1993). 6.  Cell br with a  large, subapical, nearly quadrate hyaline spot extending completely across cell and broadly touching vein R4+5  (fig.  188,  a). Other hyaline areas relatively large and often partially connected.  Coastal Washington and Oregon  ......................................... jonesi Curran 82  Volume 16, No. 1-3, March-September, 2002, INSECTA MUNDI Table 1. Gena height (measured at narrowest point in slightlyvental, lateral view with gena at maximum size), first flagellomere width in lateral view, and their ratio. Measurements in mm. include range, average and standard deviation. Sample Species  Sex  Size  Gena height bellula  male  13  0.04-0.06,0.051 ±0.007 bellula  female  13  0.05-0.08, 0.064 ±0.009 stelligera  male  16  0.075-0.105,0.091 ±0.009 stelligera  female  16  0.08-0.14,0.107 ±0.016 Cell br with a  rounded subapical hyaline  spot which is separated from vein RH5 by infuscation of varying extent. Other hyaline areas smaller and usually discrete  ...................................... 6A 6A.  Gena very narrow, height 0.040-0.080 mm., usu-ally less than 0.60 width offirst flagellomere in lateral view.  Abdominal syntergite  1+2  and tergites 3 and 4 entirely microtrichose, matte. Femora entirely yellow. Western USA,  north-western Mexico ............................ bellula Snow Gena slightly broader, height 0.075-0.140  mm., usually more than 0.67 width offirst flagellom-ere. Usually at least abdominal tergite 4 and often tergite 3 and syntergite 1+2 with lateral shiny  nonmicrotrichose  areas.  Femora  often with brown markings. Coastal British Colum-bia to Baja California  .... stelligera (Coquillett) Based on the samples of specimens measured, there is very slight overlap in the actual height of the gena  (see  Table  1),  but none in its relative height, expressed as the ratio of gena height to first flagellomere width. Males generally have a  nar-rower gena in both species, and there is probably some relationship between this character and over-all body size. The preabdominal tergites are entirely microt-richose in E. bellula except for most of  tergite 5 and in the female most of tergite 6. These tergites are microtrichose only on their basal margins. In E. stelligera there is more variation in the extent of the nonmicrotrichose abdominal areas. In addition to most of tergite 5 and female tergite 6,  there is almost always at least a small lateral bare area on tergite 4. Most specimens also have lateral nonmi-crotrichose areas on tergite 3 and many have an-other on syntergite  1+2;  in some specimens the nonmicrotrichose lateral areas on tergites 3 and 4 may be as broad as the medial microtrichose area. First flagellomere width  Ratio 0.10-0.13, 0.115  0.308-0.500, 0.445 ±0.009 0.11-0.14,0.125  0.357-0.615,0.513 ±0.008 0.105-0.15, 0.123  0.625-0.826,0.741 ±0.011 0.11-0.14,0.128  0.692-l.083,0.833 ±0.011 This character varies in a few series of  specimens of E.  stelligera examined from  southern California (Los  Angeles and San Diego  Counties),  but the lateral bare area is predominantly present (e.g., tergite  4  entirely  microtrichose  in only  3  of 24 specimens from dunes W  of Los Angeles airport (UCB) and in 2 of 8 specimens from Border Field State Beach (UCB». There is no significant difference in aculeus tip length between the two small samples I measured, but generally in E. stelligera the tip tapers slightly more rapidly and appears slightly more pointed than in most E.  bellula. The legs are consistently entirely yellow in E. bellula. Spots, streaks or occasionally larger areas of brown, often appearing blue-gray due to overly-ing dense microtrichia, are often present on the femora, especially the fore and hind femora, of E. stelligera, but are not consistently present. There may be a cline in this character, but the percentage of specimens with some markings differed consid-erably among localities within the same states. At least  a  spot  on  one  femur  was  present  in the following numbers of specimens examined for this character: 1 of 7 from British Columbia, 5 of 20 from Washington,  8  of 8  from  Oregon,  7  of  10  from northern California, 14 of30 from southern Califor-nia, and 10 of 16 from Baja California. I can see no consistent difference between E. bellula and stelligera in the markings on the back of the head. In both species there is a dark brown area on the middle of the occiput and a  usually paler, diffuse brown to blue-gray area of variable size on the postgena. Distribution. The distributions shown in Maps 1 and 2 are based mainly on specimens that I exam-ined, but some unconfirmed records that were the basis for the distribution map of E. bellula of Foote INSECTA MUNDI, Vol. 16, No. 1-3, March-September, 2002  83 \' III Map 1.  Distribution of Euaresta stelligera. A  "?"  indicates uncertain records. et  al. (1993, map 15) were included. Any that are not within the ranges based  on the  specimens I examined are noted below. Full  specimen data are available on the Systematic Entomology Laboratory  web site (see http://www.sel.barc.usda.gov/Diptera/tephritilEuar-esta/Euaresta.htm). Euaresta stelligera appears to be restricted to the coast of western North America (Map 1). I have examined  specimens from British Columbia (Queen Charlotte Islands) to northern  Baja California Norte. The only specimens I have seen that appear to be this species and that are from a locality significant-ly far from the coast are a  male and two females from Colorado: Jefferson County, Red Rocks Park, near Morrison,  6  Mar 1985,  J.  A.  Powell  (UCB USNM00054989-91). Unless mislabeled, these spec-imens represent an  interesting  Euaresta population that  should  be further investigated. Euaresta bellula occurs in the western USA (Idaho, Nevada, Utah, inland northern and wide-spread southern California, Arizona, New Mexico, western Texas) and northern Mexico (Baja Califor-nia Norte,  Baja California Sur, Sonora,  Chihua-hua)  (Map  2).  It has  been  collected  much  less commonly north of the Arizona and New Mexico borders than in southern California, Arizona and northwestern Mexico. I have not confirmed the iden-tities ofthe specimens that  were the basis ofthe data points in Utah and northern California (Merced, Plumas, Tuolumne Counties) from distribution map 15 of Foote et al. (1993), but they are probably valid. The  record from Kansas and  especiallythatfrom  Iowa are suspicious, however, and should be rechecked. According to  R. H. Foote's identification notebook, the Kansas record was based on 2 adults from Atchison 84  Volume 16, No. 1-3, March-September, 2002, INSECTA MUNDI )~ • a • Map 2.  Distribution of Euaresta bellula. A "?"  indicates uncertain records. County, Muscotah Marsh, 29 Aug 1961 (depository not stated), and  the Iowa record was based on a single specimen from Boone County, 8 Jul 1955, R.  Frye (Stoltzfus collection). The distribution pointfor south central  Texas in Foote et  al. (1993, map 15) was based on 2 misidentified males (USNM00053444) of Dys-euaresta mexicana from Hondo, but E. bellula does occur in western Texas (Davis Mountains, 10 Jul 1958, W. F. Barr, 1 female UIM USNM00056092». Host plants. Unfortunately,  few  voucher speci-mens have been preserved to document the host records that have been reported for Euaresta bellu-la (R. D. Goeden, B. A. Foote, pers. comm.), but the localities ofthese records for the most part indicate whether  they  pertain  toE. bellulaor E. stelligera. The record from male flowers of Ambrosia chamissonis (Lessing) Greene (Goeden and Ricker 1974), which has a coastal distribution  very  similar  to E. stelligera, probably pertains to E. stelligera. I have examined numerous specimens of E. stelligera collected on A. chamissonis, including specimens collected by Goeden and Ricker from several localities, but no reared specimens. I have seen  no specimens of  E. bellulafrom this plant. Foote and  Blanc (1963) reported  specimens as E. bellula "ex" A. acanthicarpa Hooker based on a series of  E. stelligera collected from Del  Monte, Cali-fornia'  by H.  H.  Severin. It is likely that these specimens were swept rather than reared, and the status of this species as a possible host plant needs further investigation. The other host plant records reported for  E. bellula appear to  truly pertain to  that species: Ambrosia ambrosioides (Cav.) Payne, female flow-ers  or  seeds (Foote 1984);A. chenopodiifolia(Bentham) Payne, male and female flowers (Foote and Blanc 1963, Goeden and Ricker 1976b); and Dicoria cane-scens Torrey and  Gray, flowers (Goeden and  Teerink 1993).Ambrosiadumosa(Gray) Payne andA. confer-tiflora DC., from which adults have been collected (Goeden and  Ricker 1976a, Berlocher 1984), are  other possible host plants. Except  for that  of  A. chenopodi-ifolia, the localities of these records are all in the distribution of  only E. bellula: Arizona (A. ambrosio-ides), New Mexico (sweep record from A. confertiflo-ra), and  inland California (D. canescens; adult  record INSECTA MUNDI, Vol. 16, No. 1-3, March-September, 2002  85 fromA. dumosa). I examined  2 males mounted along with puparia from Upper Sabino Canyon, Santa Catalina Mountains, Arizona, 24 May 1971, B. A. Foote, that were presumably reared from A. ambro-sioides, although their labels lack host data. Ambrosia  chenopodiifoliaoccurs within  the ranges of  both  fly species and  could be a host plant  of  both, but the  only  specimen  I examined  that  was reared  fromA. chenopodiifoliais a male ofE. bellulafrom California: San  Diego County, San  Ysidro, reared 23 Jun  1970 by Goeden and Ricker, ACh-70-2K (USNM00056143). The host record reported by Foote and Blanc (1963) was based  on a series (not located  by  me) also from San Ysidro. Notes on distributions of other species. Euar-esta  aequalis  (Loew):  MEXICO:  Baja  California Norte:  Cantamar, 4-6 Sep  1969, W.  Apperson,  1 male 2 females (USU, USNM; USNM00053374-6). This is the first record of this species from Mexico. Euaresta tapetis (Coquillett): UNITED STATES: Nebraska: Hooker County, Mullen, 1.5 mi. N, Mid-dle Loup River, 2-4 Ju11983, E.  E. Grissell and A. S.  Menke,  1  female  (USNM00053445).  Nevada: Humboldt County, Winnemucca,  10 mi.  N  of,  23 Jun  1971,  G.  C.  Steyskal,  4  males  3  females (USNM00053476-82). These are the first records of this species from these states, and that from Ne-braska is the first from east of Colorado and Wyo-ming. Valentibulla californica: The distribution point for this species in Foote et al. (1993, map 104) for San Nicholas Island, California was based on a mis-identified  female (USNM00053443) of  Euaresta stel-ligera, and V. californica appears not to occur on the coast. Acknowledgments I  am grateful to the numerous curators and institutions who loaned specimens for study, par-ticularly Cheryl Barr (Univ. of California, Berke-ley),  Eric Fisher (California Department of Food and Agriculture),  Ben Foote (Kent State Univ.), Dick Goeden (Univ. of  California, Riverside), Wilford Hanson (Utah State  Univ.), Frank  Merickel (Univ. of Idaho), Jere Schweikert (California Academy of  Sci-ences)'  and R.  O.  Schuster (Univ.  of California, Davis). The following kindly reviewed the manu-script: Wayne Mathis, Steve Lingafelter, and Nor-man  Woodley. Literature Cited Batra, S. W.  T.  1979. Reproductive behavior of Euaresta  bella  and  E.  festiva  (Diptera:  Te-phritidae), potential agents for the biological control of adventive North American ragweeds (Ambrosia spp.) in Eurasia. Journal ofthe New York Entomological Society 87: 118-125. Berlocher, S. H. 1984. Electrophoretic evidence for the validity of Euaresta stelligera Coquillett (Diptera: Tephritidae). Journal of the Kansas Entomological Society 57: 354-357. Foote, B. A.  1984. Host plant records for North American ragweed flies (Diptera: Tephritidae). Entomological News 95: 51-54. Foote, R. H. and F. L. Blanc. 1963. The fruit flies or  Tephritidae  of  California. Bulletin  of  the Cali-fornia Insect Survey 7: 117 p. Foote, R. H., F. L. Blanc and A. L. Norrbom. 1993. Handbook of the fruit flies (Diptera: Te-phritidae) of America north of Mexico.  Com-stock Publishing Associates, Ithaca. 571 p. Goeden,  R.  D.  and D.  W.  Ricker.  1974.  The phytophagous  insect fauna  of the  ragweed, Ambrosia chamissonis, in southern California. Environmental Entomology 3:  835-839. Goeden, R.  D.  and D. W.  Ricker.  1976a. The phytophagous  insect  fauna  of the  ragweed, Ambrosia dumosa, in southern California. En-vironmental Entomology 5:  45-50. Goeden, R.  D. and D. W. Ricker.  1976b. The phytophagous insect faunas of the ragweeds, Ambrosia chenopodiifolia,  Ambrosia eriocen-tra, Ambrosia ilicifolia in southern California. Environmental Entomology 5: 923-930. Goeden, R. D. and J. A. Teerink. 1993. Phytoph-agous insect faunas of Dicoria canescens and Iva  axillaris,  native  relatives  of ragweeds, Ambrosia spp.,  in southern  California,  with analyses of insect associates of Ambrosiinae. Annals of  the Entomological Society of  America 86: 37-50. Norrbom, A. L., L. E. Carroll, F. C. Thompson, I. M. White and A. Freidberg. 1999. System-atic database of names, pp. 65-251. In F.  C. Thompson (ed.), Fruit Fly Expert Identification System and Systematic Information Database. Myia (1998) 9, vii + 524 pp. and Diptera Data Dissemination Disk (CD-ROM) (1998) 1. Quisenberry,  B. F. 1950. The genus Euaresta in  the United States (Diptera: Tephritidae. Journal of the New York Entomological Society 58: 9-38. 

The status of Euaresta stelligera (Coquillett) (Diptera: Tephritidae)

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