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VOL. 104

JULY 2002

NO. 3

(ISSN 0013-8797)


of the






BLANK, STEPHAN M. Taxonomic notes on Strongylogasterini (Hymenoptera: Tenthredinidae) 692

BUFFINGTON, MATTHEW L. Description of Aegeseiicoela Buffington, new name, with notes

on the status of Gronotoma Forster (Hymenoptera: Figitidae: Eucoilinae) 589

CHABOO, CAROLINE S. Range extensions of New World tortoise beetles (Coleoptera:

Chrysomelidae: Cassidinae) 716

FLORES, GUSTAVO E. and CHARLES A. TRWLEHOKH—Entomohalia, new genus, the first

member of Nycteliini (Coleoptera: Tenebrionidae) from Brazil 602

GOEDEN, RICHARD D. Life history and description of immature stages of Oxyna palpalis (Coquillett) (Diptera: Tephritidae) on Artemisia tridentata Nuttall (Asteraceae) in southern California 537

GOEDEN, RICHARD D. Life history and description of immature stages of Goedenia rufipes (Curran) (Diptera: Tephritidae) on Isocoma acradenia (E. Greene) E. Greene in southern California 576

GOEDEN, RICHARD D. Life history and description of immature stages of Goedenia setosa (Foote) (Diptera: Tephritidae) on Ericameria hrachylepis (A. Gray) H. M. Hall in southern California 629

GOEDEN, RICHARD D. Life history and description of adults and immature stages of Goedenia stenoparia (Steyskal) (Diptera: Tephritidae) on Gutierrezia californica (de CandoUe) Torrey and A. Gray and Solidago californica Nuttall (Asteraceae) in southern California 702

GOEDEN, RICHARD D. Life history and description of adults and immature stages of Goedenia steyskali, n. sp. (Diptera: Tephritidae) on Grindelia hirsutula Hooker and Arnott var. halli (Steyermark) M. A. Lane (Asteraceae) in southern California 785

HARRISON, B. A., R B. WHITT, S. E. COPE, G. R. PAYNE, S. E. RANKIN, L. J. BOFIN, F M. STELL, and C. J. NEELY Mosquitoes (Diptera: Culicidae) collected near the Great Dismal Swamp: New state records, notes on certain species, and a revised checklist for Virginia 655

(Continued on back cover)




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PROC. HNTOMOL. SOC. WASH. 104(3). 2002, pp. 537-553





Richard D. Goi^dhn

Department of Entomology. University of Calirornia. Riverside, CA 92521, U.S.A. (e- mail: richard.goeden@ucr.edu)

Abstract. Oxyna palpalis (Coquillett) is a univoltine, circumnatal tephritid uniquely reproducing as an inquiline in rosette galls of Rhopalomyia fiorella Gagne (Diptera: Ce- cidomyiidae) of terminal buds on branches of Artemisia trideiitata Nuttall. Its larvae also routinely function as facultative predators of R. jiorella larvae, novel behavior for Te- phritidae. The egg, first-, second-, and third-instar larvae, and puparia are described and figured for the first time. The egg is distinguished by a pedicel circumscribed by one complete and a partial second ring of irregularly shaped micropyles. All three larval instars of O. palpalis are compared to and distinguished from those of O. aterrima (Doane), its only other known congener in North America. Oviposition occurs in spring (June) in southern California in nearly fully formed galls of R. jiorella containing young larvae of this cecidomyiid. The young larvae of O. palpalis pass the summer (June-September) as first instars singly in small, central, ovoidal cells basad of the cecidomyiid larvae. Second instars occupy their still-small, separate chambers until late fall/early winter (September- October), when some begin to molt to third instars. By mid-winter (February) all larvae are third instars, which continue to overwinter and grow slowly until the resumption of the spring flush of new plant growth (March). At this time, one to six or more third instars enlarge the central gall chamber to accommodate their faster growth and feed gregariously. Cecidomyiid larvae encountered during this third stadium are killed and devoured; sur- viving immature gall midges usually occupy the periphery of the galls. Pupariation follows in early April, and adults emerge by mid-April. Eutytoma sp. (Hymenoptera: Eurytomi- dae) and Eiipelmus sp. (Hymenoptera: Eupelmidae) were individually reared from puparia of O. palpalis as primary, solitary, probably larval-pupal endoparasitoids. Lyrcus sp. (Hy- menoptera: Pteromalidae) was reared from individual puparia as a gregarious, primary endoparasitoid.

Key Words: Insecta, Oxyna, Asteraceae, Artemisia, nonfrugivorous Tephritidae, Rho- palomyia, Cecidomyiidae, biology, taxonomy of immature stages, galls, inquiline. circumnatal life cycle, parasitoids, insect predation

Oxyna palpalis (Coquillett) (Diptera: Te- O. aterrima (Doane) was reviewed by

phritidae) is one of two species of Oxyna Foote et al. (1993) and studied by Goeden

now known from North America (Foote et (2002b), who synonymized it with O. utah-

al. 1993, Goeden 2002b). The other species, ensis Quisenberry.



Materials and Methods

The present study was based in large part on dissections of samples of galls of the gall midge, Rhopalomyia florella Gagne (Diptera: Cecidomyiidae), on Artemisia tri- dentata Nuttall prob. ssp. parishii (A. Gray) H. M. Hall and Clements (Asteraceae) col- lected mainly 0.2 km north of the hamlet of Mile High and just south of the hamlet of Largo Vista; 1580-m elevation; Township 4N, Range 9W. Section 4; Angeles National Forest, Los Angeles Co., during 1996 and 1997. Excised R. florella galls, containing eggs and early-instar larvae of O. palpalis, and later, overwintered galls containing third instars and puparia of O. palpalis were sampled mid-monthly from gall-bearing plants during 1996 and 1997. Samples were transported in cold-chests in an air-condi- tioned vehicle to the laboratory and stored under refrigeration for subsequent dissec- tion, photography, description, and mea- surement. Eight eggs, 18 first-, seven sec- ond-, and 19 third-instar larvae and nine puparia dissected from galls were preserved in 70% EtOH for scanning electron micros- copy (SEM). Additional prepuparia and pu- paria in excised, opened galls were placed in separate, glass shell vials stoppered with absorbant cotton and held in humidity chambers at room temperature for adult and parasitoid emergence. Specimens for SEM were hydrated to distilled water in a de- creasing series of acidulated EtOH. They were osmicated for 24 h, dehydrated through an increasing series of acidulated EtOH and two, 1-h immersions in hexa- methyldisilazane (HMDS), mounted on stubs, sputter-coated with a gold-palladium alloy, and studied and photographed with a Philips XL-30 scanning electron micro- scope in the Central Facility for Advanced Microscopy and Microanalysis, University of California, Riverside.

Most adults reared from isolated prepu- paria and puparia were individually caged in 850-ml, clear-plastic, screened-top cages with a cotton wick and basal water reser-

voir and provisioned with a strip of paper toweling impregnated with yeast hydroly- zate and sucrose. These cages mainly were used for studies of longevity in the insec- tary of the Department of Entomology, University of California, Riverside, at 25 ± rC, and 14/10 (L/D) photoperiod. Two pairs of virgin flies, each consisting of a male and a female obtained from emer- gence cages also were held in a clear-plas- tic, petri dish provisioned with a flattened, water-moistened pad of absorbant cotton spotted with honey (Headrick and Goeden 1994) for observations of their courtship and copulation behavior.

Plant names used in this paper follow Hickman (1993) and Bremer (1994); te- phritid names and adult terminology follow Foote et al. (1993); cecidomyiid names and gall terminology follow Gagne (1989). Ter- minology and telegraphic format used to describe the immature stages follow Goe- den (2001, 2002a, b), Goeden and Nonbom (2001), Goeden and Teerink (1999), and earlier works cited therein. Means ± SE are used throughout this paper. All remaining voucher specimens and reared parasitoids of this tephritid reside in my research col- lections. Digital photographs used to con- struct text figures were processed with Ado- be Photoshop® Version 6.

Results and Discussion

Adult. Oxyna palpalis originally was described as a Tephritis by Coquillett in Baker (1904) from a single male specimen from Ormsby County, Nevada. Quisenberry ( 1949) in his revision of Oxyna redescribed this species from three females and two males variously from California, Idaho, and Nevada. Foote and Blanc (1963) and Foote et al. (1993) pictured the right wing.

Immature stages. The egg, first-, sec- ond-, and third-instar larvae, and puparium of O. palpalis are described below.

Egg: Thirteen eggs of O. palpalis dis- sected from field-collected galls of R. flo- rella galls also bearing cecidomyiid larvae were white, opaque, smooth, ellipsoidal,



Fig. 1. Egg of Oxyiui pal/nilis: (A) habitus, anterior to left; (B) pedicel 1, (C) pedicel 2, (D) pedicel 3. (The three pedicels show variation in size, shape, and placement of micropyles.)

0.65 ± 0.02 (range. 0.62-0.68) mm long, 0.20 ± 0.00 (range, 0.20-0.20) mm wide, smoothly rounded at basal end, with a 0.2- mm, buttonlike pedicel at anterior end (Fig. lA). The pedicel was circumscribed suba- pically by one complete and a partial sec- ond ring of inegularly shaped micropyles (Fig. IB, C, D)

This is the first Oxyna egg pictured at high magnification (Goeden 2002b). On av- erage, the egg of O. palpalis is slightly lon- ger and slightly narrower than that of O. aterrima (Goeden 2002b).

First instar kir\'a: White, ellipsoidal, flat- tened anteriorly and posteriorly (Fig. 2A); body segments with hemispherical or pos- teriorly-directed, short-spinose, minute acanthae on intersegmental areas of meta- thorax and abdominal segments A 1 through A6 as well as pleura and lateroventrum of

Al through A6; prothorax and gnathoce- phalon smooth, the latter conical (Fig. 2B), both circumscribed by verruciform sensilla (Figs. 2B-1, -2); dorsal sensory organ, well- defined, flat pad (Fig. 2C-1); anterior sen- sory lobe (Fig. 2C-2) bears terminal sen- sory organ (Fig. 2C-3), lateral sensory or- gan (Fig. 2C-4), supralateral sensory organ (Fig. 2C-5), and pit sensory organ (Fig. 2C- 6); stomal sense organ reduced to two ver- ruciform sensilla ventrolaterad of terminal sensory organ (Figs. 2C-7, D- 1 ), not fused with flattened, protrudent, lateral integu- mental petal (Figs. 2C-8, D-2) above each mouthhook, one medial, papillate, integu- mental petal (Figs. 2C-9, D-3) between an- terior sensory lobes and lateral integumen- tal petals; mouthhook bidentate (Figs. 2B- 3, C-10, D-4); median oral lobe laterally compressed, apically rounded (Figs. 2B-4,



Fig. 2. First instar of Oxyna palpalis: (A) habitus, anterior to left, (B) gnathocephalon and prothorax. ven- trolateral view, 1 verruciform sensilla on gnathocephalon, 2 verruciform sensilla on prothorax, 3 mouth- hook, 4 median oral lobe; (C) gnathocephalon, frontal, close-up view, I dorsal sensory organ, 2 anterior sensory lobe, 3 terminal sensory organ, 4 lateral sensory organ, 5 supralateral sensory organ, 6 pit sensory organ, 7 stomal sense organ, 8 lateral integumental petal, 9 medial integumental petal, 10 mouthhook; (D) oral cavity, ventral view, I stomal sense organ, 2 lateral integumental petal, 3 medial integumental petal, 4 mouthhook, 5 median oral lobe, 6 labial lobe, 7 pores.

D-5); labial lobe (Fig. 2D-6) broad, sepa- rated from median oral lobe, and with two pores ventrally (Fig. 2D-7); anterior spira- cle absent; lateral spiracular complexes not seen; caudal segment (Fig. 3A) with a ste- lex sensillum dorsolaterad (Fig. 3A-1), lat- erad (Figs 3A-2, B), and ventrolaterad (Figs. 3A-3, C-1) of posterior spiracular plate (Figs. 3A-4, D); posterior spiracular plate bears two rimae (Fig. 3D-1), ca. 0.005 mm long, and four, unbranched or bifurcate, spinose or apically toothed (some bifurcate) interspiracular processes (Fig. 3D-2), the longest process measuring 0.007 mm; in- termediate sensory complex (Figs. 3A-5, C-

2, D-3) consists of stelex sensillum (Fig. 3C-3) and medusoid sensillum (Fig. 3C-4). The habitus of the first instar of O. pal- palis is similar to the first instar of O. ater- rima; however, as with Trupanea spp. (Goeden and Teerink 1999), Neaspilota spp. (Goeden 2001), and Tephritis spp. (Goeden 2002a), the incidence and patterns of minute acanthae on the thorax and ab- domen show interspecific differences. Ox- yna palpalis has fewer minute acanthae in the intersegmental areas of the thorax and abdominal segments Al and A2, and unlike O. aterrima, none on or between abdominal segments A3 through A6 (Goeden 2002b).



Fig. 3. First instar of O.xyiui pcilpcilis. continued: (A) caudal segment. 1 dorsolateral stelex sensilla, 2 lateral verruciform sensillum, 3 ventrolateral stelex sensillum, 4 posterior spiracular plate, 5 intermediate sensory complexes; (B) lateral stelex sensillum (anow); (C) 1 ventrolateral verruciform sensillum, 2 inter- mediate sensory complex (composed of), 3 stelex sensillum, 4 medusoid sensillum; (D) posterior spiracular plate with 1 two rimae, 2 four interspiracular processes, and 3 two intermediate sensory complexes.

The first instar of O. atern'nia has two. medial, integumental petals (Goeden 2002b); whereas, O. palpalls has only one (Figs. 2C-9, D-3). The single, lateral inte- gumental petal above each mouthhook is fused with the stomal sense organ in O. aterrinia (Goeden 2002b), but they are not fused in O. palpalis (Figs. 2C-8, D-2). The mouthhooks are tridentate in the first instar of O. ateniiua (Goeden 2002b), but are bi- dentate in O. palpalis (Figs. 2B-3, C-10, D- 4). The lateral sensilla surrounding the pos- terior spiracular plate of O. aterrinui are verruciform (Goeden 2002b: whereas, these are stelex sensilla in O. palpalis (Figs 3A- 2, B). The interspiracular processes on the caudal segment of O. aterrinia are un- branched (Goeden 2002b); whereas, some

processes of O. palpalis are two-branched (Fig. 3D-2).

Second instar larva: Ovoidal, rounded anteriorly, truncated posteriorly (Fig 4A), body segments with short-spinose, posteri- orly-directed, minute acanthae (Fig. 48- 1) circumscribing intersegmental areas of tho- rax and abdomen; thorax and gnathoce- phalon smooth (Fig. 48), the latter conical, the former circumscribed around middle with verruciform sensilla (Fig. 48-1); dor- sal sensory organ, a well-defined, flat pad (Figs. 4C-1, D-1); anterior sensory lobe (Fig. 4C-2) with terminal sensory organ (Fig. 4C-3), lateral sensory organ (Fig. 4C- 4), supralateral sensory organ (Fig. 4C-5), and pit sensory organ (Fig. 4C-6); two pairs of foliose, protrudent, lateral integumental



' SI a .,v

Fig. 4. Second instar of O.xyiui palpalis: (A) habitus, anterior to left; (B) prothorax and gnatiiocepiiaion, frontolateral view, I minute acanthae, 2 verruciform sensillum; (C) gnathocephalon, frontolateral view, I dorsal sensory organ, 2 anterior sensory lobe, 3 terminal sensory organ, 4 lateral sensory organ, 5 supra- lateral sensory organ, 6 pit sensory organ, 7 lateral integumental petals, 8 medial integumental petals; (D) gnathocephalon, ventrolateral view, 1 dorsal sensory organ, 2 lateral integumental petals, 3 ventral, medial integumental petals, 4 oral ridges, 5 stomal sense organ, 6 mouthhook, 7 median oral lobe. 8 labial lobe, 9 pores.

petals (Figs 4C-7, D-2) above each mouth- hook, two pairs of papillate, medial inte- gumental petals (Fig. 4C-8) between each anterior sensory organ, the ventral pair elongate (Fig. 4D-3); at least four oral ridg- es (Fig. 4D-4) ventrolaterad of each anterior sensory lobe and stomal sense organ (Fig. 4D-5); mouthhook (Fig. 4D-6) with two teeth; median oral lobe laterally flattened (Fig. 4D-7); labial lobe (Fig. 4D-8) broad, separated from median oral lobe, with two pores ventrally (Fig. 4D-9); anterior thorac- ic spiracle (Fig. 5A) with five, rounded, wedge-shaped papillae; lateral spiracular complexes not seen; caudal segment (Fig. 5B) with stelex sensillum dorsolaterad

(Figs. 5B-1), laterad (Fig 5B-2), and ven- trolaterad (Figs. 5B-3, C- 1 ) of posterior spi- racular plate (Figs. 5B-4, D); posterior spi- racular plate with four, elongate, upright, foliose, interspiracular processes (Fig. 5D- 1), the longest process measuring 0.011 mm; intermediate sensory complex (Figs. 5B-5, C-2) consists of stelex sensillum (Fig. 5C-3) and medusoid sensillum (Fig. 5C-4). One major difference between the second instars of O. palpalis and O. aterrima is the absence of a black marking on the abdom- inal ventrum of the former species, where the ventrum and pleura of the latter species are densely covered with knoblike minute acanthae (Goeden 2002b). In O. palpalis



Fig. 5. Second instar i)f Oxyiui palpalis, continueLi: (A) anterior spiracle; (B) caudal segment: caudal seg- ment. 1 dorsolateral stelex sensilla. 2 lateral stelex sensilla. 3 ventrolateral stelex sensilla, 4 posterior spiracular plate. 5 intermediate sensory complexes; (C) 1 ventrolateral stelex sensillum. 2 intermediate sen- sory complex (composed of). 3 stelex sensillum. 4 medusoid sensillum; (D) posterior spiracular plate. 1 four interspiracular processes.

the minute acanthae are short-spinose and confined mainly to the intersegmental areas of the thorax and abdomen. Oxynci palpalis has two pairs of medial integumental petals between each anterior sensory lobe (Fig. 4C-8); whereas, O. aterrima has only one such pair (Goeden 2002b). The inner, ven- tral oral ridge among the four such ridges of O. aterrima is ventrally toothed and fused with the stomal sense organ (Goeden 2002b); whereas, none of the four oral ridg- es of O. palpalis is toothed nor fused with the stomal sense organ (Figs. 4D-3, 4).

Third instar lana: Pale yellow or white, ovoidal. tapering anteriorly, truncated pos- teriorly, distinctly segmented (Fig. 6A), short-spinose, posteriorly-directed, minute acanthae in transverse bands on dorsopos-

terior fifth of gnathocephalon (Figs. 6A, B- 1 ). minute acanthae also circumscribe an- terior fourth of thoracic segments and an- terior fourth of abdominal segment Al. dor- sum, ventrum and anterior third of pleura of A2-A7, and all but posterior of spiracular plate A-8 (Fig. 7D-1); gnathocephalon smooth, conical (Fig. 6-B); dorsal sensory organ well-defined, hemispherical (Figs. 6B-2. C-1 ); anterior sensory lobe bears ter- minal sensory organ (Figs. 6B-3, C-2), lat- eral sensory organ (Fig. 6C-3), supralateral sensory organ (Fig. 6C-4), and pit sensory organ (Fig. 6C-5); nine or 10 oral ridges (Fig. 6D-1 ) laterad and ventrolaterad of an- terior sensory lobe and stomal sense organ, at least six lobes ventrally toothed and sep- arate from prominent stomal sense organ



^g^w'^m^ Hj^j

Fig. 6. Third iiisuir ol (Jxyini jhiIjuiH.',: (A) habitus, anterior to led; (B) gnathoccphalon, ventrolateral view, 1 minute acanthae, 2 dorsal sensory organ, 3 terminal sensory organ, 4 stomal sense organ, 5 mouth- hook, 6 median oral lobe, 7 lateral integumental petal, 8 inner, lateral integumental petals; (C) gnatho- cephalon, dorsolateral view, 1 dorsal sensory organ, 2 terminal sensory organ, 3 lateral sensory organ, 4 supralateral sensory organ, 5 pit sensory organ, 6 stomal sense organ. 7 medial integumental petals, 8 lateral integumental petals, 9 inner, lateral integumental petals; (D) gnathocephalon and oral cavity, ventrolat- eral view, 1 oral ridges. 2 three-toothed mouthhook. 3 median oral lobe, 4 lateral integumental petals, 5 inner, lateral integumental petal, 6 labial lobe, 7 pores; (E) anterior spiracle with three papillae; (F) anterior spiracle with four papillae.



(Fig. 6B-4, C-6); moulhhook (Fig. 6B-5, D- 2) tridentate (Fig. 5D-2); median on\\ lobe laterally flattened, apieally rounded (Figs. 6B-6, D-3); three pairs of medial integu- mental petals in vertical row between an- terior sensory lobes (Fig. 6C-7); five, lateral integumental petals between each mouth- hook and anterior sensory lobe, including four foliose, lateral petals (Fig. 6B-7. C-8. D-4) and single, inner, elongate, papillate, lateral petal (Figs. 6B-8, C-9, D-5); labial lobe (Fig. 6D-6) broad, separated from me- dian oral lobe, and with two pores ventrally (Fig. 6D-8); anterior thoracic spiracle with three (Fig. 6E, 7A-I) or four, rounded, wedge-shaped papillae (Fig. 6F); lateral spiracular complex of mesothorax with closed, relict spiracle (Fig. 7A-2) and six verruciform sensilla (Figs. 7A-3) in vertical row posteriorad of spiracle, additional ver- ruciform sensillum posteriorad of fourth- most-vertical sensillum; lateral spiracular complex of metathorax similarly composed of closed, relict spiracle (Figs. 7A-4, B-1) and four veiTuciform sensilla (Figs. 7A-5, B-2) similarly positioned; lateral spiracular complex of first abdominal segment com- posed of closed, presumably relict spiracle (Figs. 7A-6, C-1) and three verruciform sensilla (Figs. 7A-7, C-2) similarly posi- tioned; posterior spiracular plate (Figs. 7D- 1, 8 A) bears three, broadly elliptical rimae (Fig. 8A-1), ca. 0.03 mm long, and four, unbranched, spiniform, interspiracular pro- cesses (Fig. 8A-2), each ca. 0.007 mm long; stelex sensilla dorsolaterad (Figs. 7D-2, 8B), verruciform sensilla laterad (Figs. 7D- 3, 8C), and stelex sensilla ventrolaterad (Fig. 7D-4) of posterior spiracular plate; in- termediate sensory complexes (Figs. 7D-5, 8D) consist of stelex sensillum (Fig. 8D-1) and medusoid sensillum (Fig. 8D-2).

Fortunately, the third instars of both spe- cies of Oxyna known from North America have now been described in considerable detail, facilitating comparison between them. For example, the minute acanthae on third instars of O. atenima are fewer in number, occupy fewer body segments, and

form different patterns (Goeden 2002b) than the minute acanthae on O. palpalis. O.yyiui jHilpcilis has at least nine or 10 oral ridges (Fig. 6D- 1 ), six of which have ven- trally toothed margins; whereas, O. aterri- iiHi has only two oral ridges (Goeden 2()()2b). All live lateral integumental petals of third inslar O. alcninm are papillate (Goeden 2()()2b); whereas, only one of the five lateral integumental petals of the third instar of O. palpalis is papillate, the rest are foliose (Figs. 6B-7, C-8, D-4). The lateral spiracular complex of the mesothorax of O. atenima has four verruciform sensilla (Goeden 2002b); whereas, this same com- plex in O. palpalis has seven verruciform sensilla (Figs. 7A-3). Similarly, the lateral spiracular complex of the first abdominal segment of O. atenima has four verruci- form sensilla, two pairs in separate vertical rows, (Goeden 2002b); whereas, this same complex in O. palpalis has three, vertical, verruciform sensilla (Figs. 1 A.-1, C-2).

The caudal segments of third instars of these congeners also differ considerably. The dorsolateral, lateral, and ventrolateral sensilla surrounding the posterior spiracular plate of O. atenima are all verruciform. The intermediate sensory complex of this species also uniquely consists of two ver- ruciform sensilla, and this composition dis- tinguishes O. atenima from third instars of all other nonfrugivorous tephritids exam- ined by my coworkers and me to date (Goe- den 2002b). In O. palpalis, the dorsolateral and ventral lateral sensilla are stelex in form (Figs. 7D-2, -4E, 8B), and the inter- mediate sensory complex is comprised of a stelex sensillum (Fig. 8D-1) and a medu- soid sensillum (Fig. 8D-2), like all other third instars described by us to date.

Differences noted between the first and second instars of O. palpalis include the usual acquisition of an anterior spiracle in the second instar, the increase in the number of lateral integumental petals from one to three, and the drastic change in shape of the interspiracular processes (Figs. 3D-2, 5D- 1). Differences noted between the second




Fig. 7. Third instar of Oxyua pulpalis. continued: (A) lateral spiracular complexes, 1 anterior spiracle, 2 metathoracic spiracle, 3 verruciform sensillum, 4 mesothoracic spiracle, 5 verruciform sensillum, 6 first abdominal segment spiracle, 7 verruciform sensillum; (B) part of lateral spiracular complex of metathorax, 1 spiracle, 2 verruciform sensillum, (C) part of lateral spiracular complex of metathorax. 1 spiracle, 2 ver- ruciform sensillum; (D) anal segment. I posterior spiracular plate, 2 dorsolateral stelex sensillum, 3 lateral verruciform sensillum, 4 ventrolateral stelex sensillum. 5 intermediate sensory complexes.

and third instars include a change in the in- cidence of the minute acanthae as described above. Other changes include increases from three (Fig. 4C-7) to five (Figs. 6B-7; B-8; C-9; D-4, -5) in the number of lateral integumental petals, which all are foliose in the second instar, but add a central, papillate petal in the third instar. Two pairs of medial integumental petals are present in the sec- ond instar (Fig. 4C-8); whereas, three pairs occur in the third instar (Fig. 6C-7). The anterior spiracles with five papillae in the second instar (Fig. 5A) compare with three (Figs. 6E, 7A-1) or four papillae (Fig. 6F) in the third instar. The sensilla surrounding the posterior spiracular plate are the same in number as in the second instar; however.

in the second instar the lateral sensilla are stelex (Fig. 5B-2), not verruciform, as in the third instar (Figs. 7D-3, 8C). The inter- spiracular processes on the posterior spirac- ular plate of the second instar are larger, foliose, and upright (Fig. 5D-1) compared to the small, resupinate, spiniform process- es of the third instar (Fig. 8D-2).

Puparia: Reniform-ellipsoidal, light-, yellow-, or reddish-brown, rarely white (Fig. 9B), anterior end bears the invagina- tion scar and anterior thoracic spiracles; caudal segment bears posterior spiracular plates (Fig. 9C), each with three broadly el- liptical, raised rimae (Fig. 9C-1) and four, interspiracular processes (Fig. 9C-2). One hundred and five puparia averaged 3.04 ±



Fig. 8. Third instar of O.xyiici palpalis. continued: (A) po.sterior spiracular plate, 1 three rimae, 2 four inter.spiracular processes, (B) dorsolateral stelex sensillum. (C) lateral verruciform sensillum, (D) intermediate sensory complex, 1 stelex sensillum, 2 medusoid sensillum, 3 minute acanthae.

0.03 (range, 2.13-3.70) mm in length; 1.60 ± 0.016 (range. 1.14-1.99) mm in width.

Distribution and Hosts

Oxyna palpalis uniquely reproduces as an inquiline in the rosette galls of Rhopa- lomyia fiorella of terminal buds on branch- es of Artemisia tridentata in southern Cal- ifornia. In this capacity it also functions as a facultative predator on the larvae and pu- pae of R. fiorella (see below), which also renders this tephritid rare and fascinating in the annals of tephritidology. Novak et al. (1967) reported that the larvae form small, succulent, polythalamous galls on small branches of A. tridentata in Idaho, but as documented in the next section of this pa- per, this interpretation was incorrect, as O. palpalis is not a gall-former. Foote et al. (1993) mapped the distribution of O. pal-

palis to include California, Idaho, Nevada, Oregon, Utah, Washington, and Wyoming. Thus, like that of O. aterrirna (Goeden 2001b), the distribution of O. palpalis may coincide wholly with A. tridentata sensu latu, or in part with one or more of its sub- species (Hickman 1993). This is a shrub that inhabits dry soils, valleys, slopes from 300 to 3000+ m in the western U.S., i.e.. north to Washington, the North Central States and south to New Mexico (Hickman 1993). The distribution of A. tridentata also extends into southwestern Canada (Barkley 1986).


Egg. In each of 31, nearly fully formed rosette galls of Rhopalomyia fiorella (Gag- ne 1989) already containing larvae of this cecidomyiid (Fig. lOA), most of 51 eggs of



A' ^

Fig. 9. Oxymi palpulis. (A) prepuparium, habitus, anterior to left; (B) puparium, habitus, anterior to left; (C) posterior spiracular plate, 1 three rimae, 2 four interspiracular processes.

O. palpalis were found inserted separately, a few in small clusters, pedicel-last, in leaf bases to depths of half to all of the egg lengths (Fig. lOB). Leaves at the margins or in the centers of the galls received the

most oviposition, but a few eggs were layed upon, but not penetrating the tissues be- tween adjacent bases of inner or outer leaves. About half of the eggs lay with their long axes parallel to the long axes of the galls (Fig. lOB); the remainder lay at angles of to 45° to the long axes. Oviposition in galls was scattered throughout a stand of A. tridentata, like and sympatric with the galls of R. florelki, and not confined to certain individual host-plants galled repeatedly over successive years (Headrick and Goe- den 1998). This is similar to the pattern of the incidence of galls of O. aterrima (Goe- den 2002b). Some galls bore tephritid eggs on opposite sides that showed different de- grees of embryony, presumably indicative of oviposition by different females at dif- ferent times. An average of 3.4 ± 0.4 (range, 1-10) eggs was found in these 31 galls. Galls containing eggs of O. palpalis (Fig. lOA) averaged 6.3 ± 0.4 (range, 4.3- 1 1.5) mm in length, and 4.0 ± 0.2 (range, 0.6-6.8) mm in width. The linear leaves in- vesting these galls averaged 3.5 ± 0.3 (range, 2.0-8.6) mm in length and 0.9 ± 0.04 (range. 0.6-1.3) mm in width.

Larva. Upon eclosion, most first instars of O. palpalis tunneled into the center of the gall basad of the young, cecidomyiid larvae and leaf bases (Fig. IOC), where each first instar remained for up to 3 months within an individual, ovoidal, open, smooth-walled cell. An average of 2.3 ± 0.2 (range. 1—5) first instars of O. palpalis were found in a total of 53 infested galls sampled monthly during the first 3 months following oviposition, during which time the subspheroidal (smaller) (Fig. lOA) to hemispheroidal (larger) galls averaged 6.9 ± 0.3 (range, 3.1-11.5) mm in length and 4.8 ± 0.2 (range, 2.9-7.4) mm in width. The linear leaves laterally surrounding the galls averaged 4.4 ± 0.2 (range, 1.4-8.6) mm in length and 0.9 ± 0.03 (range, 0.6- 1 .4) mm in width. Seventy-three ovoidal to spheroidal cells containing the first instars of O. palpalis averaged 0.78 ± 0.09 (range, 0.28-4.6) mm in length and 0.48 ±0.18



(range. 0.21-0.99) nun in width. The si/e of most of these cells containing first instars slowly increased during the first stadium. Unfortunately, the number of cecidomyiid larvae was not recorded in most galls; how- ever. 14 galls containing Hrst instars of O. palpalis also were noted to contain an av- erage of 2.2 ± 0.5 (range. 1-8) larvae of R. florella. Also, it was subsequently noted that most galls o{ R. florella without O. pal- palis contained only a single, centrally lo- cated larva (Fig. IID). Thus, some galls containing first instars of O. palpalis also contained dead, centrally located, cecido- myiid larva(e) presumably killed after ac- cidental contact with a tephritid larva. In- deed, at least for later instars of O. palpalis in those many galls found to be lacking R. florella (see below), this relationship may represent nutritionally advantageous, facul- tative predation.

The larva next molted to the second in- star (Fig. lOD). evidenced as the cast ce- phalopharyngeal skeleton remaining in the cell. This instar may also last about 3 months and is one stage found in overwin- tering galls in southern California (see be- low). The external dimensions of 28 galls found to contain second instars measured 6.8 ± 0.3 (range. 3.7-11.4) mm in length by 5.7 ± 0.3 (range, 2.9-8.6) mm in width. The linear leaves investing these galls av- eraged 4.6 ± 0.3 (range, 1.7-9.1) mm in length and 1.1 ± 0.04 (range, 0.7-1.7) mm in width. These 28 galls each contained an average of 1.8 ± 0.2 (range. 1-6) second instars of O. palpalis (Fig. lOD). Two of these galls (7%) contained two and three larvae clustered together in a central, com- mon, open cavity. The remaining 26 galls contained one or more second instars in separate, open, ovoidal cells (Fig. lOD) that averaged 1.3 ± 0.06 (range. 0.6-2.0) mm in length and 0.8 ± 0.04 (range. 0.4-1.1) mm in width. Thus, the galls grew little on average during the second stadium, as did the cells containing individual second in- stars of O. palpalis (Fig. lOD). Ten galls were recorded to contain dead larvae of R.

florella or none, the latter of which was pre- sumed to reflect complete consumption by (). palpalis, but again, cecidomyiid inci- dence was not recorded in another 10 of these galls, so the incidence of cecidomyiid mortality may actually have been higher.

O.xyna palpalis also overwinters as third instars in southern California (Figs. lOE, F). This is the stage during which the greatest amoiml of larval growth and attendant in- crease in gall cavity size takes place (Figs. I OF. F). Seventy-eight galls containing third instars of O. palpalis averaged 8.9 ± 0.2 (range. 5.1-13) mm in length by 7.4 ± 0.2 (range. 2.1-4.5) mm. The linear leaves laterally surrounding the galls averaged 5.3 ± 0.2 (range. 2.2-10.8) mm in length and 1.2 ± 0.03 (range. 0.9-1.7) mm in width. Thus, on average, galls increased little, if any. in size during the equally slow growth of the third instars during the winter through early spring, when in response to renewed plant growth following winter rainfall, the cavities that contained the third instars expanded to accomodate the fast- growing, O. palpalis larvae. The 65, frass- lined, ovoidal or irregularly shaped, cen- trally located, open cells that contained sin- gle instars of O. palpalis within these 78 galls averaged 2.6 ± 0.1 (range. 1.1-5.1) mm in longest measurement by 1.7 ± 0.1 (range. 0.57-2.9) mm in shortest measure- ment, or about twice as large as cells con- taining single second instars. Moreover, in galls containing two or more third instars (Figs. lOE, F) these central cavities aver- aged 3.3 ± 0.2 (range, 1.7-5.1) mm in lon- gest length by 2.6 ± 0.2 (range, 0.85-4.6) mm in shortest width, or, again, more than twice as large on average than cavities con- taining single second instars, or those with single third instars, sometimes occupying much of the interior of smaller galls. All told, the 78 galls contained an average of 1.7 ± 0.1 (range, 1-5) third instars (Figs. lOE. F). The lateral thickness of the walls of these galls averaged 1.8 ± 0.6 (range, 1.1-2.9) mm, which afforded insufficient spatial protection from parasitoids (see be-



Fig. 10. Life stages of Oxyna palpalis in galls of Rhopalomyia florella: (A) partly grown gall of R. florella that contained egg of O. palpalis, (B) egg of O. palpalis (arrow) in gall of R. florella. (C) newly eclosed, first instar of O. palpalis (arrow) tunneling into center of gall. (D) two, overwintering second instars of O. palpalis in separate chambers (arrows), (E) four third instars of O. palpalis in common, central cell in gall. (F) 1 newly formed puparium and 2 full-sized larva of O. palpalis. and 3 pupa of R. florella in same gall. Lines = I mm.

low) that attacked the third instars and pu- paria of O. palpalis. All told, third instars were found in samples over an 8-month pe- riod, 6 months into which, puparia first ap- peared in monthly gall samples.

Pupa. Near the end of the third larval stadium, the third instar transformed into a preparium (Fig. 9A), which in O. palpalis was of relatively short duration. No window to facilitate future adult egress from the

galls was formed in the gall wall, unlike the windows made by O. aterrima third instars prior to prepupal formation (Goeden 2002b). The prepuparia of O. palpalis (Figs. 9A, IOF-2) transformed into puparia within the larval cells or among the cottony tomentum (Fig. lOF-1). which by then also contained pupae (Fig. lOF-3) or empty pu- pal exuviae of emerged, surviving R. flo- rella, usually found on the periphery of a



Fig. 11. Life stages of O.xyna palpalis in galls of R/iopaloiiiyia florella. continued, (A) two puparia of O. palpalis in gall, (B) full-size gall that contained puparia of O. palpalis. (C) single central puparium of O. palpalis in gall, (D) single, central pupa of R. florella in gall, (E) male adult of O. palpalis, (F) female adult of O. palpalis. Lines = 1 mm.

gall (Fig. lOF-3). The anterior end of the puparium of O. palpalis usually faced dis- tad, away from the base of the gall (Figs. lOF-1, 11). Eighty-four mature galls (Figs. 1 IB, C) sampled over a 2-mo period con- tained an average of 1.5 ± 0.1 (range. 1-5) puparia of O. palpalis. These galls exter- nally averaged 9.1 ± 0.2 (range, 5.7-15.0) mm in length by 7.9 ± 0.2 (range, 5.0- 11.4) mm in width. The linear leaves lat- erally surrounding the galls averaged 7.1 ± 0.3 (range, 2.6-16) mm in length and 1.4

± 0.03 (range, 0.8-2.5) mm in width. Sixty (71%) of the 84 galls each contained a frass-lined, ovoidal or inegularly shaped, central cavity that held a single puparium of O. palpali.s (Fig. IIC), which averaged 3.4 ± 0.1 (range, 2.3-6.3) mm in longest measurement by 2.0 ± 0.1 (range, 1.1-3.4) mm in shortest measurement. Whereas, in galls containing two or more puparia (Fig. 1 lA) these central cavities averaged 4.1 ± 0.2 (range, 2.9-5.7) mm in longest length by 3.2 ± 0.1 (range, 2.3-4.6) mm in short-



Table 1. Incidence of Oxyiia palpalis in galls of Rhopalomyia florella on Artemisia tricleiitata on sam- ple dates indicated.

R florella Galls


No. WithoiH

No. With

Sample Date

O. palpalis 1 9; )

O. palpalis ( '7r )


49 (84)

9 (16)

l.v. 1996

51 (84)

10 (16)

7.V. 1996

55 (79)

15 (21)

5.vi. 1996


15 (?)

I8.vi. 1996

12 (38)

20 (62)

I6.vii. 1996

15 (56)

12 (44)

I3.viii. 1996

25 (71)

10 (29)

I6.ix. 1996

76 (87)

11 (13)

16.x. 1996

35 (81)

8 (19)


60 (79)

16 (21)

IS.xii. 1996

40 (70)

17 (30)

16.i. 1997

20 (71)

8 (29)

12.ii. 1997

34 (63)

20 (37)

13.iii. 1997

65 (81)

25 (19)

9.iv. 1997

76 (76)

24 (24)

16.iv. 1997

69 (78)

19 (22)

30.iv. 1997

45 (80)

II (20)

est width, again, sometimes occupying much of the interior of smaller galls. The central location of a single pupa of R. flo- rella in a gall without O. palpalis (Fig. 1 ID), when compared to a similarly located puparium of O. palpalis typical of the 60 galls containing single individuals noted above (Fig. 1 IC), most of which lacked any sign of R. florella, strongly suggests a high incidence of facultative, or at least acciden- tal predation by the tephritid on the ceci- domyiid. Table 1 records the incidence of O. palpalis in galls of R. florella on differ- ent sample dates.

Adult. Adults exited galls presumably by pushing