DESCRIPTIONS OF THE FINAL INSTAR LARVAE OF ARGIA SABINO GARRISON AND ARGIAPIMA GARRISON (ODONATA : COENAGRIONIDAE)

10 Pages·1999·4.3 MB·

by  J D Hoekstra

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.