PROC. ENTOMOL. SOC. WASH. 101(4), 1999. pp. 887-896 DESCRIPTIONS OF THE FINAL INSTAR LARVAE OF ARGIA SABINO GARRISON AND ARGIA PIMA GARRISON (ODONATA: COENAGRIONIDAE) Jon D. Hoekstra and Robert L. Smith Department of Entomology, University of Arizona, Tucson, AZ 85721, U.S.A. (e-mail: [email protected]); (JDH) Current address: Illinois Natural History Survey, Cen- ter for Aquatic Ecology, 607 E. Peabody Dr., Champaign, IL 61820 (e-mail: hoek- stra®mail.inhs.uiuc.edu). — Abstract. We illustrate and describe the final instar larvae of Argia sabino Garrison 1994 and Argia pima Garrison 1994 based on preserved exuviae and larvae from Sabino Creek, Arizona, U.S.A. A dichotomous key is provided to integrate A. sabino andA. pima into an existing larval key to North American Argia spp. Key Words: Arizona, damselflies, Zygoptera, larval taxonomy, Argia Argia sabino Garrison is a species of small streams, particularly in the south- conservation concern because of its limited western U.S. and southward into the Neo- range and possible endemism. The species tropics. For example, eleven Argia species is known from only three localities globally are known from Sabino Canyon (R.W. Gar- and from only one U.S. breeding population rison, personal communication). At any at Sabino Creek, Arizona (Garrison 1994). given time or location, up to eight of the Argia pima Garrison is closely related toA. Sabino Canyon species may be common or sabino and the two species are sympatric at quite abundant (personal observation). Sabino Creek. Here we describe the final Our descriptions include a treatment of instar larvae of both species. This project the male and female gonapophyses, which was undertaken in support of studies on the Novelo-Guiterrez (1992) showed to be habitat requirements ofA. sabino. highly diverse and taxonomically useful We Argia is a diverse odonate genus, con- structures within the genus. also pro- taining about 110 species (Garrison 1994). vide a diagnosis of the larvae, and integrate The larvae of the genus are poorly known. the two species into Westfall and May's Of 36 North American Argia spp., Westfall (1996) key to North AmericanArgia larvae. and May (1996) provide a key to identify Methods and Materials the larvae of 29 species. Larvae of only 28 Argia spp. have been formally described Argia larvae in all stages ofdevelopment (Novelo-Guiterrez 1992). Continued pro- were collected from Sabino Creek, Arizona, gress in describing larvae will benefit our U.S.A. in May 1996 and from March to understanding of the evolution and system- July 1997. Collections were made with a atics ofthe group. In addition, development standard D-frame aquatic collecting net of comprehensive larval keys to Argia will from shallow areas of pools, primarily by facilitate ecological studies of benthic in- lifting or turning rocks and scooping up dis- vertebrates in many habitats. Frequently, lodged substrate and invertebrates. The net several species of Argia are sympatric in was also swept among submerged root mas- 888 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON ses and leaf litter. Argia larvae were main- gins, a cluster of 3-8 basidorsal stout setae, tained at 20°C on a 14:10 (L:D) cycle in and a series of 3-7 fine, short dorsoapical 120 ml plastic specimen containers that setae; basidorsal and dorsoapical setae were supplied with a strip of cordura nylon sometimes absent. Ligula strongly to mod- webbing as a clinging substrate. Larvae erately prominent, with closely set minute were fed mosquito larvae, Daphnia, ostra- claviform setae along margin. Premental cods, and tubificid worms ad libitum (late- palpus with 3 (sometimes 2) long dorsal instars were primarily fed tubificid worms) hairlike setae; dorsal movable hook (brown) until they emerged. Final stadia ceased and pair of ventral hooks present; the ven- feeding when emergence was imminent. At tral pair longer than dorsal hook and tinged this time, each larval container was provid- with brown. Thorax: Pronotum with scat- ed with an emergence stick and placed in tered stout setae and usually a pair ofdorsal an emergence chamber (inverted 3.8-liter spots. Lateral pronotal margins produced glass condiment jar) to contain the imago. with clump of stout setae. Synthorax rela- All exuviae and some larvae were pre- tively dark with obscure patterning. Wing served in 80% EtOH. Teneral adults were sheaths with dark bands as shown in Fig. allowed to harden until they could be iden- 1; tips of posterior pair typically extend to tified and then were preserved in 80% the posterior margin of abdominal tergite 4. EtOH with the associated larval exuviae. Stemites unpigmented with scattered fine We measured exuviae and larvae with a setae and a single long fine seta anteromesal Lasico model S-4 auto-scaler. Illustrations to each mesocoxa. Femora with 2 dark were prepared with a camera lucida at 12X transverse bands each, the distal band larg- (dorsal habitus), 25X (prementum and la- er; bands narrower than intervening spaces. mella), and 50X (gonapophyses) magnifi- Profemur with regularly spaced stout setae cation. along posterior, anterior, dorsal, and ventral margins; stout setae fewer in similar posi- Descriptions tions on meso- and metafemora. Tibiae with dark transverse band slightly basal to center Argia sabino Garrison 1994 and usually with dark area near articulation (Figs. 1-5) with femora. Tarsi 3-segmented, light — brown, with pair of strongly curved claws. Final instar larva. Robust; ground col- Tibiae and tarsi with thick dorsal growth of oration pale to medium brown; markings long fine setae. Stout setae along ventral deep brown to black. Measurements pre- margin of tibiae; setae increasing in extent sented in Table 1. Head: Dorsum of head and number to form dense patch near api- patterned as shown (Fig. 1). Ocelli visible ces. Several setae near apices trifurcate, as white semicircular depressions. Cephalic comblike. Ventrally directed, finer stout se- lobes with dorsum irregularly patterned; tae present in two rows along ventrolateral posterolateral margins of lobes broadly an- edges of tarsi. Abdomen (excl. appendag- gulate, darkly pigmented, and with a fringe es): Abdominal tergites 1 and 2 usually un- of stout setae. Antenna 7-segmented; scape pattemed; 3 and 4 variable, often with ir- broad, short with apical fringe offine setae; regular dark patterns; 5-7 with dorsolateral pedicel longer, broad with rounded apex; and lateral dark blotches paired about dor- remaining segments elongate. All segments sal midline, these blotches continuous with light brown. Antennomere lengths (from posterior margin and tapering anteriorly in basal to distal) approximately as 0.4: 0.7: tergum 7; 8 and 9 primarily deep brown 1.0: 0.9: 0.5: 0.3: 0.1. Labium pale to me- with light areas centered on midline and ta- dium brown. Prementum (Fig. 2a) with pering abruptly to thin line posteriorly; 10 stout setae along distal 0.4 of lateral mar- notched with lateral faces dark and broad VOLUME 101. NUMBER 4 889 mm 3 Fig. 1. Dorsal habitus offinal instar larva, Argia sabino. 890 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON Table \. Measurements* of final instar larvae, Argia sahino and Ari^ia pima. VOLUME NUMBER 101. 4 891 A. sabino A. pima mm 1 3a A. sabino pima Figs. 2-3. Labiumand lateral lamella. 2, Prementum, dorsal view; a,Argia sabino. b,A. pima. 3, Leftlateral lamella, lateral view; a, A. sabino, b, A. pima. PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OE WASHINGTON 892 4a ttJI'^ VVi i A. pima A. sabino mm 0.5 A. sabino A. pima ::-„Lr.rr,t^"/n=t:::-s^^^^^^ VOLUME NUMBER 101. 4 893 based on the following specimens: U.S.A., pendages): Setation of abdominal tergites Arizona, Pima County, Santa Catalina Mts., as in A. sabino. Abdominal color pattern Sabino Creek, under stones and in detritus similar to that of A. sabino, except white m in pools. Collected at 990-1,190 on var- areas on dorsum oftergites 8 and 9 not nar- ious dates, IV-10-97-VII-10-97. Exuviae: 3 rowing posteriorly. Abdominal tergites 1 males, 4 females, Florida State Collection and 2 mostly pale; 3-5 with dark lateral ar- of Arthropods, International Odonata Re- eas and a paler bilobed marking centered search Institute (FSCA/IORI); 2 males, 3 on dorsal midline; 6-7 with dorsolateral females. University of Arizona Insect Col- and lateral dark blotches paired about dor- lection (UAIC). Larvae: 1 male, 3 females, sal midline, these blotches often continuous FSCA/IORI; 1 male, 2 females, UAIC. with posterior margin and tapering anteri- orly on 7; 8 and 9 primarily deep brown Argia pima Garrison 1994 with light stripe centered on midline; 10 (Figs.—2-6) notched with lateral faces dark and broad Final instar larva. Similar in overall pale area centered on dorsal midline, this habitus toA. sabino but larger (Table 1) and pale dorsal stripe widening posteriorly. slightly more elongate; ground coloration Stout setae present along lateral pleura of usually darker than in A. sabino, medium segments 3-10. Setation and coloration of brown; markings deep brown to black (Fig. stemites as in A. sabino except stout setae 6). Head: Patterns on dorsum of head sim- less robust and abundant, especially on 8. ilar to those in A. sabino, but less distinct. Caudal lamellae: Caudal lamellae saccoid- Ocelli, antenna, overall shape of head, and laminar, basally inflated to a greater degree setation and shape of cephalic lobes as in than in A. sabino, with moderately accu- A. sabino. Antennomere lengths approxi- minate tips. Lateral lamellae (Fig. 3b) 2.5 mately as 0.4: 0.7: 1.0: 0.8: 0.6: 0.2: 0.15. times as long as wide with lateral external Labium pale to light brown; prementum carinae extending along basal 0.4 of length (Fig. 2b) with stout setae along distal 0.5 of lamella and bearing stout setae; stout se- of lateral margins, a cluster of 6-10 basi- tae present along the basal 0.1 and 0.4 of dorsal stout setae, and usually with 1-3 dor- dorsal and ventral margins, respectively. soapical fine setae; these less prominent Median caudal lamella without lateral ca- than in A. sabino. Ligula moderately prom- rinae; analogous lengthwise keel with a few inent; minute claviform setae set along api- stout setae near base of gill; stout setae cal margin; an additional pair of minute along basal 0.2 and 0.15 of dorsal and ven- claviform setae also present, recessed from tral margins. Lateral lamellae largely vel- margin of ligula. Premental palpi usually vety black; with light areas at basal 1/10 with 2 hairlike setae, rarely with 3 on one and a small pale spot roughly at center of palpus; palpal hooks as in A. sabino. Tho- gill; distal dorsal and ventral edges of gill rax: Pronotum with scattered stout setae often with mottled, wedge-shaped areas but lacking pair of dorsal spots. Lateral converging on pale central spot (Fig. 3b). pronotal margins with prominent knob cov- In some individuals, mottled areas nearly ered with stout setae. Synthorax and wing reach central spot. Median caudal lamella pad patterns as in A. sabino; tips of poste- similar in pigmentation to lateral lamellae, rior pair of wing pads typically extend to but with markings more diffuse and with posterior margin of abdominal tergite 3. light areas more extensive than in lateral Stemites pale with scattered fine setae. Pig- lamellae. Gonapophyses and cercus: Male mentation and setation patterns of legs as gonapophyses (Figs. 4c, d) light brown, in A. sabino, except dark areas on tibiae more elongate than those ofA. sabino, with near articulation with femora usually more acute tips parallel and extending to poste- extensive and distinct. Abdomen (excl. ap- rior 0.4 of tergum 10. Basal 0.7 of venter PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON 894 mm 3 Fig. 6. Dorsal habitus offinal instar larva, Argia pima. VOLUME 101, NUMBER 4 895 of gonapophyses with series of 10-15 prin- length of the ventral margin only, much cipal and several smaller stout setae direct- less on dorsal margin, sometimes nearly ed posteroventrally; 2-4 fine setae also lacking 15 15(1'). Lateral gills with a fringe of stout setae present. Male cercus as inA. sabino, except extendingalong at leastthebasalVsofthe distance between cerci in dorsal view usu- ventral margin 16 ally greater than their maximum width. Fe- 15'. Lateral gills with ventral setae absent or male gonapophyses (Figs. 5c, d) with acute restricted to the basal V4 of the ventral tips of outer pair slightly divergent and ex- margin (taxa not included here) tending beyond end of tergum 10. Tips of 16(15). Usually with 2 palpal setae; lateral gills either primarily dark or pale with a dark inner pair extend to or beyond tips of outer medial band and stout setae along basal pair in ventral view. Basal 0.8 of venter of Vi ofdorsal edge ofgill 17 outer pair with series of 15-20 principal 16'. Usually with 3 or 4 palpal setae; lateral and several smaller stout setae; 6 principal gills either primarily pale with dark mot- and several—smaller fine setae also present. tling orpale with brown speckles, butnot as above 20 Remarks. Variability noted for A. sa- 17(16). Lateral gills more than 2.25X as long as bino also exists in A. pima. In particular, wide; spiniformsetaeonatmostbasal0.2 extension of abdominal segments may be of dorsal margin; gill surface primarily extreme in specimens preserved post mor- dark with restricted light areas 18 tem. Some individuals are very darkly pig- 17'. Length of lateral gills subequal to 2x mented. The above description is based on their width; spiniform setae on basal Vz of the following specimens: U.S.A., Arizona, dorsal margin; gill usually mostly pale with dark medial transverse band miinda Pima County, Santa Catalina Mts., Sabino . . 18(17). Lateral gills almost uniformly dark; dor- Creek, under stones and in detritus in pools. sumofabdomen eitherunmarkedorwith m Collected at 1,100-1,190 on VI-6-96 and continuous broad pale dorsal stripe ... 19 on various dates. III-17-97-VII-10-97. Ex- 18'. Lateral gills primarily dark, but with pale uviae: 3 males, 4 females, FSCA/IORI; 2 basal area, central pale spot, and some- males, 2 females, UAIC. Larvae: 1 male, 4 dtiomressumirorefgualbadrompialnealarseeagsmeanstsin9Fiagn.d31b;0 females, FSCA/IORI, 4 females, UAIC. with pale dorsal stripe, other segments variously patterned but without continu- Diagnosis ous dorsal stripe (Fig. 6) pima Larvae of A. sabino and A. pima could 19(18). Ligula barely prominent, distinctly less not be integrated into the larval key of convex than in A. pima (Fig. 2b); abdo- North American Argia (Westfall and May men with broad, continuous pale middor- sal stripe lacrimans 1996) without modifying couplet 16 and subsequent couplets. We restructured the 19'. cLiognuvleaxmaosdeirnatA.elpyipmraom(iFniegn.t,2b)a;t ldeoarstsuams key, based on published information, to ac- ofabdomen largely pale and withoutdor- conrmiodate A. sabino andA. pima. The key sal stripe tonto below is valuable primarily in determining 20(16'). Lateral gills 2.5-3X as long as wide,pri- specimens collected from southern Arizona marily pale but with extensive dark mot- tled areas ordark transverse bands; fem- and Mexico. All figures referred to are con- oradistinctly banded withbandsnarrow- tained in this publication. er than spaces between them 21 20'. Lateral gills 2X as long as wide or less, Key to North American Arg/a Larvae surfaces pale with brown speckles; fem- (After Westfall and May 1996) ora not distinctly banded or bands wider 1. Lateral gills with marginal fringe ofstout than intervening spaces alberta setae for at least % their length on both 21(20). Abdomen with distinct, continuous, pale the ventral and dorsal margins (taxa not middorsal stripe 22 included here) 21'. Abdomen without a distinct pale mid- 1'. Lateral gills with marginal fringe ofstout dorsal stripe for its entire length; pale setae extending at most about % the stripe usually present on segments 8-10 896 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON butdoesnotextendthroughanteriorseg- their width; in A. sabino, this gap is usually ments (Fig. 1) sabino subequal to or less than the width of the 22(21). Lateral gill widestatorjust beyond Vi its cercus. Second, the stout setae on the gon- length, diffusely mottled (sometimes with faint transverse bands) anceps apophyses of A. sabino are relatively few 22'. Lateral gill widest at about % its length, (fewer than 12 principal setae) and small. with 2or3 well-markedtransversebands Stout setae are more numerous (more than tarascana 12 principal setae) and larger on the gona- pophyses ofA. pima. Discussion Acknowledgments Argia sabino is very similarin adultmor- phology to A. tarascana Calvert, its sister This work was funded partially by the species (Garrison 1994). The larvae of A. U.S. Fish and Wildlife Service Ecological tarascana (Westfall 1990, Novelo-Guiterrez Services Office, Phoenix, Arizona. Thanks 1992) are similar to those of A. sabino as go to Carole Mclvor of the University of Arizona School of Renewable Natural Re- well, but in addition to the difference in ab- dominal color pattern described above, sources for her initial work to obtain fund- there also is a structural difference in fe- ing for this research. Thanks also to Lorena male gonapophyses (especially as seen in Wada ofthe U.S.F.W.S. Ecological Services lateral view). A parallel situation exists for Office for continuing interest in the project. A. pima; its sister species is Argia lacri- The staff of the Coronado National Forest mans Hagen (Garrison 1994). The larvae of provided access and permits necessary to these species are fairly distinct; beyond the complete this research. The first author characters used in our key, differences in thanks the University of Arizona Depart- the abdominal color pattern and the shape ment of Entomology and the ARCS and setation of the male gonapophyses also (Achievement Rewards for College Scien- distinguish the two species (compare with tists) Foundation for financial support dur- figures for A. lacrimans in Novelo-Guiter- ing the time in which this work was com- rez 1992). pleted. Hoekstra also thanks his wife, Tina Separating larvae of A. sabino and A. L. Carrington, for assistance with fieldwork pima is an important objective for ecolog- and for moral support necessary to com- ical and conservation studies in Sabino plete this work. Canyon. No characters have been found to Literature Cited separate early-instar larvae of the two spe- Garrison, R. W. 1994. A synopsis of the genus Argia cies, but for mature larvae this determina- ofthe United States with keys and descriptionsof tion is not difficult provided well-formed new species, Argia sabino, A. leonorae. and A. lamellae are present. Lamellae are frequent- pima (Odonata: Coenagrionidae). Transactions of ly absent or in early stages of regeneration the American Entomological Society 120: 287— in late-instar larvae. In this case, female lar- 386. vae can be separated by a character of the Novelo-Guiterrez, R. 1992. Biosystematics of the lar- vae of the genus Argia in Mexico (Zygoptera: gonapophyses: the inner pair of gonapo- Coenagrionidae). Odonatologica 21: 39-71. physes extends to the tips of the outer pair Westfall, M. J. 1990. Descriptions of larvae oiArgia or beyond in A. pima (Figs. 5c, d), whereas munda Calvert, A. plana Calvert, A. tarascana the inner pair is recessed inA. sabino (Figs. Calvert, and A. tonto Calvert (Zygoptera: Coena- grionidae). Odonatologica 19: 61-70. 5a, b). Separation ofmales without lamellae Westfall, M. J. and M. L. May. 1996. Damselflies of is more difficult. In A. pima, the distance North America. Scientific Publishers, Gainesville, between the pharate cerci usually exceeds Florida, U.S.A. 649 pp.