Proceedings of the Entomological Society of Washington
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PROC. ENTOMOL. SOC. WASH. 92(4). 1990, pp. 649-671 THE ASPHONDYLIA (CECIDOMYIIDAE: DIPTERA) OF CREOSOTE BUSH (LARREA TRIDENTATA) IN NORTH AMERICA Raymond J. Gagne and Gwendolyn L. Waring (RJG) Systematic Entomology Laboratory, PSI, Agricultural Research Service, USDA, Vo U.S. National Museum NHB 168, Washmgton, D.C. 20560, USA; (GLW) Museum of Northern Arizona, Rt. 4, Box 720, Flagstaff, Arizona 86001, USA. Abstract.— ¥\^Xttn species of gall midges of the genus Asphondylia that form complex galls on leaves, stems, or buds of creosote bush are described. Fourteen of the species are new to science, the other is redescribed. One other species that was caught in flight and is similar to the leaf gall makers of Larrea is also redescribed. The Asphondylia spp. on creosote bush appear to be a monophyletic group and are treated as the Asphondylia auripila species group. Key Words: Complex galls, Southwestern desert, gall midges Fifteen distinct kinds of complex galls tion between the southwestern North growing on leaves, stems, and buds of Lar- American and South American deserts. rea tridentata (Sesse & Mocino ex DC.) Cov. Larrea tridentata is the only species oi Lar- (Zygophyllaceae) were found by G. L. War- rea in North America, while four others oc- ing during the course of an ecological study cur in southern South America (Waring of this plant. Each type of gall is formed by 1986). a different species of the genus Asphondylia. Asphondylia is a large, cosmopolitan ge- all of them except one new to science. In nus of 247 described species (Foote 1965, this paper we describe or redescribe these Gagne 1968, Gagne 1973, Gagne in press, gall midges and place them in context with Gagne in prep., Harris 1980, Skuhrava one another and with the rest of the genus. 1986). To date, 67 species have been de- The natural history, ecology, and natural scribed from the Nearctic Region (Gagne in enemies of these flies have been or will be prep.). Almost as many more Nearctic treated separately in Waring (1987), Waring species are known but not yet described and Price ( 1 989a, b), and Waring (in prep- (Gagne 1989). Gagne (1989) listed the de- aration). scribed and undescribed Nearctic species Larrea tridentata, or creosote bush, is a and their hosts and discussed Asphondylia dominant member of southwestern desert in general. A thorough generic analysis of plant communities from Texas to California the tribe (as a supertribe) to which the genus (Mabry et al. 1977, Waring 1986). It is a belongs was done by Mohn (1961). The perennial, evergreen shrub, and one of the Nearctic species of Asphondylia have not most drought-tolerant plants in southwest- been revised since Felt (1916), but recent em United States. Larrea is restricted to the studies were made of a monophyletic group New World and is one ofmany taxa of plants of eight species that occurs on Chenopodi- and animals that show a disjunct distribu- aceae in California (Hawkins et al. 1986) 650 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON v: <y' >¥< ^ ^-^^ -r^ 9 Fig. 1 . Stem and bud galls of Larrea Indeniaia formed by Asphondylia spp. Sprig of plant in 1 x , details of X galls in 3 . la: Stem gall of.-l. aunpila. the detail with outer leaves removed to show the mdividual cells beneath; b. stem galls of A. foliosa: c, stem gall of.-l. rosella: d, apical bud gall of.-l. apicata; e, node galls of.-l. butlata; f flower gall of A. Jlorea; g, stem galls of .4. resinosa. the resin of one of the enlarged pair removed to show detail. and oi Asphondylia websteri Felt, an appar- species, such as Asphondylia monacha Os- ent generalist known from some Fabaceae ten Sacken and relatives, have black- and and other plants (Gagne and Wuensche white-banded legs and are otherwise cov- 1986, Gagne and Woods 1988). In addition, ered with black scales. Females have a rigid, one of us (RJG) made a survey for this study protrusible, needlelike ovipositor (Figs. 7, of certain characters on all known described 8) with which they insert their eggs into liv- Nearctic species. ing plant tissue. Larvae are generally white Asphondylia adults are between 1-5 mm to yellow, have three instars, and always in length and are relatively robust with cy- occur singly, either taking up the entire gall lindrical antennae, large eyes, and an almost or an individual cell in aggregate galls. The complete covering of scales. They are gen- last instar is robust and has a spatula (Figs. erally brown to dark brown, but some 35^7), a hard, brown to black dermal struc- VOLUME 92, NUMBER 4 651 x Fig. 2. Leaf galls oi Larrea Iridentata formed by Asphondylia spp. Sprig of plant in 1 , details of galls in 3x. 2a: Galls of. 4. harbala; b. galls of.-l. villosa; c, galls of.-l. discalis: d, gall of.-l. siliciila; e, galls of.-l. pilosa; f, gall of.-l. fahalis: g. galls of .-). clavala: h, galls of .4. digilata. ture on the first segment of the thorax. All be relegated to any one of the six species. It species in the genus pupate in the galls. The is redescribed here as a sixteenth species but pupa is also robust, and its integument is not treated further in our discussion of the hard and brown or black. Its head has horns auripila group. of various kinds and dorsally the abdomen Materials and Methods is covered with spines, all of which serve to effect escape from the galls. Galls were collected when fully developed Of the 1 5 species of Asphondylia associ- and were separated by type. Some galls were ated here with as many different kinds of cut open to obtain samples of larvae, which galls on Larrea. Asphondylia auripila Felt were preserved in 70% alcohol. The re- is the only one previously described. One mainder of the galls were isolated in plastic other species, Asphondylia brevicauda Felt, bags with absorbent tissue paper in order to is known from a single female without host rear adult gall midges and parasitoids. The association. That female is similar to those bags were kept at room temperature and out from six kinds of galls on creosote bush but of direct light. After adults had emerged, without associated immature stages cannot they and their pupal exuviae were kept in SOCIETY OF WASHINGTON 652 PROCEEDINGS OF THE ENTOMOLOGICAL dlh. frontal view. 4, Detail of mouthparts 3-9 Adult structures of Asphondvlia spp. 3, Head of .4. clavata, Figs segments '3 genitalia of .4. resmosa. lateral. 7. Abdominal of Fig 5 Detail of mouthparts of .4. harhata. 6. Male A. resmosa. A. resinosa. 9. Fore, mid, and hind tarsal claws, 7 to end of female A. clavata. lateral. 8, Same, VOLUME 92, NUMBER 4 653 Figs. 10-15. Pupal heads of Asphondyhu spp., lateral view on left, ventral on right. 10, 11. .1. aunpila. 12, \3, A. foliosa. 14, 15,^4. resinosa. 70% alcohol. Examples of the galls were kept adult body parts follows that of McAlpine that either in alcohol or dry. et al. ( 1 98 1 ); larval terminology follows For microscopic examination, examples in Gagne (1989). of larvae and adults were mounted on slides The species from Larrea are described in Canada balsam according to the tech- here in a fashion comparable to that of the nique outlined in Gagne (1989). Samples of species on Atriplex in Hawkins et al. ( 1 986) pupae were critical-point dried and placed and of .4. websteri in Gagne and Wuensche on stubs for SEM photos. Terminology of (1986). We believe the Asphondylia spp. on 654 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON VOLUME 92, ^^JMBER 4 655 Larrea to be monophyletic, so will refer to terminable in most species because most them collectively here as the Asphondylia available adults were preserved in alcohol auripila group. Because so many characters instead of dry on pins). are common to all the creosote bush species, Head (Figs. 3-5): Antenna: scape broad- a combined description of the group is made est distally, 1.6-1.8 times length pedicel, at the outset to avoid repetition in the in- pedicel about as wide as long; first flagello- dividual descriptions that follow. mere 2.1-2.3 times length of scape, evenly The descriptions and redescriptions of cylindrical. Eye facets close together, hex- these species are in alphabetical order so agonoid. Frons with 5-20 setae per side, they can be easily found, but the plates of variable in number within a species. La- figures treat the species in natural groupings. bellum reduced in size, laterally with 0-4 All types and other material examined are (usually 2-3) setae and setulose, and medi- deposited in the National Museum of Nat- ally with 4-6 short, basiconic setae. Palpus ural History in Washington, D.C. 1 or 2-3 segmented: when 1 segmented, usu- The 14 new species are given adjectival ally elongate spherical, tapering at the apex, names that describe some aspect of their and with 2-5 scattered setae; when 3 seg- galls, either their shape or their position on mented, first segment always short and nar- the plant: apicata = apical; barbata = beard- rower than the second and with 0-3 setae, ed or hairy; buUata = knobby; clavata = and the second and third segments some- clubshaped; digitata = digitate; discalis = times fused or only partly separated, the platelike; fabalis = beanshaped; florea = of second widest and usually shorter than the the flower; foliosa = leafy; rosetta = rosette; third, which tapers to a pointed end; second pilosa = hairy; resinosa = resinous; silicula and third segments each with 2-10, mostly = podlike; villosa = hairy.