Baumann, R.W., and B.P. Stark 2017. Variation in the epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), 
with comments on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
http://zoobank.org/urn:lsid:zoobank.org:pub:602D4DFC-273B-4DDC-8EB0-D60D68503B71 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 1 
 
 
VARIATION IN THE EPIPROCT OF ARSAPNIA DECEPTA BANKS, 1897 
(PLECOPTERA: CAPNIIDAE), WITH COMMENTS ON  
ARSAPNIA COYOTE (NELSON & BAUMANN 1987) 
 
 
Richard W. Baumann1 & Bill P. Stark2  
 
1 Department of Biology and Monte L. Bean Life Science Museum, 
Brigham Young University, Provo, Utah, U.S.A. 84602 
E-mail: richard_baumann@byu.edu 
 
2 Department of Biology, Box 4045, Mississippi College, Clinton, Mississippi, U.S.A. 39058 
E-mail: stark@mc.edu 
 
 
 
 
 
 
ABSTRACT 
Epiprocts and tergal processes were examined using scanning electron microscopy for scattered 
populations of Arsapnia decepta Banks, 1897 and A. coyote (Nelson & Baumann, 1987) from throughout their 
known ranges. Epiproct lengths ranged from 379-578 μm among A. decepta males from 19 sites, and from 
575-618 μm for A. coyote males from two sites. Among A. decepta males, the numbers of thick spine-like 
epiproct setae ranged from 10-34 per cluster. We conclude that A. decepta, as currently defined, shows 
considerable variation in epiproct dimensions, numbers of epiproct setae per cluster, and width of the 
dorsal process on tergum 7. In addition, the limited data from our small sample of A. coyote specimens, and 
the molecular data published recently by colleagues, support continued recognition of this closely related 
species. SEM images are presented to document the observed variation in these structures from various 
populations in western North America. 
 
Keywords: Plecoptera, Capniidae, Arsapnia decepta, A. coyote, epiproct morphology, scanning electron 
microscopy 
 
 
 
 
INTRODUCTION 
The genus Arsapnia was originally proposed by 
Banks (1897), but was placed as a synonym of Capnia 
Pictet, 1841 by Claassen (1924), where it remained 
until Murányi et al. (2014) re-established the group 
as a valid Nearctic genus based on the eight 
members of the Arsapnia decepta species group 
(Nelson & Baumann 1989). Arsapnia decepta Banks, 
1897 is presently known from scattered populations 
in Arizona, Colorado, Mexico (Baja California; 
Chihuahua), New Mexico, and Nevada (DeWalt et 
al. 2017, Jewett 1966, Kondratieff & Baumann 2002, 
Nelson & Baumann 1989, Sargent et al. 1991). Our 
preliminary observations of epiproct morphology 
for Eagle Creek, New Mexico and Redstone, 
Colorado populations showed significant variation 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 2 
in numbers of spine-like setae clustered dorsally on 
the epiproct surface (10-15 vs 19-24 respectively) 
and epiproct length (413 μm vs 525 μm 
respectively). Consequently, we chose to evaluate 
epiproct variation with SEM among populations 
identified as A. decepta from throughout the range of 
the species. We also comment on A. coyote (Nelson 
& Baumann, 1987b), considered the sister species of 
A. decepta, and known only from southern California 
where A. decepta has not been reported (Nelson & 
Baumann 1987b, 1989). 
 
MATERIALS AND METHODS 
Samples of A. decepta stored in 75-80% ethanol 
were obtained from the Bill P. Stark collection at 
Mississippi College, Clinton, Mississippi (BPSC), 
C.P. Gillette Museum of Arthropod Diversity, 
Colorado State University, Fort Collins, Colorado 
(CSUC), and the Monte L. Bean Life Science 
Museum, Brigham Young University, Provo, Utah 
(BYUC). Samples from which scanning electron 
micrographs were made are listed below as 
“Material examined”. No attempt was made to list 
all localities where A. decepta populations are 
known. 
Wings were removed from specimens and the 
bodies sonicated for 10-15 seconds to remove debris. 
Cleaned specimens were inspected under a SZH10 
Olympus dissecting microscope, or a Wild M-8 
stereoscope, and then dehydrated through 90, 95 
and 100% ethanol for 10 minutes each. 
Subsequently, specimens were transferred to 
hexamethyldisilizane (HMDS) for 30-60 minutes 
before mounting on aluminum stubs using double 
sided adhesive copper tape. Stubs were sputter 
coated with gold palladium and examined with an 
Amray 1810 scanning electron microscope at 
Mississippi College, or a Philips XL30 ESEM FEG 
microscope at the Brigham Young University 
Electron Microscopy Laboratory. Epiproct 
terminology follows that of Nelson & Baumann 
(1989). 
 
 
 
 
 
RESULTS 
 
Arsapnia decepta Banks, 1897 
Shortbeak Snowfly 
 
Arsapnia decepta Banks, 1897:22. Type series (4 
specimens), Fort Collins [Larimer Co.], Colorado 
(Museum of Comparative Zoology) 
Capnia decepta: Claassen, 1924:43. 
http://lsid.speciesfile.org/urn:lsid:Plecoptera.speciesfile.org:
TaxonName:4975 
 
Capnia barbata Frison, 1944:153. Holotype ♂ (Illinois 
Natural History Survey), Longmont [Larimer Co.], 
Little Thompson River, Colorado (Synonymy Nelson 
& Baumann, 1989) 
http://lsid.speciesfile.org/urn:lsid:Plecoptera.speciesfile.org:
TaxonName:4976 
 
Colorado Populations 
(Figs.1-12) 
 
Material examined. USA: Colorado: Boulder Co., 
Gregory Creek, Gregory Canyon Trail, 39.9977, -
105.2997, 2 February 2015, C. Verdone, 3♂ (CSUC). 
Larimer Co., Buckhorn Creek, 5 mi above 
Masonville, 40.5723, -105.4504, 16 March 1991, B.C. 
Kondratieff, 46♂, 9♀ (CSUC). Cedar Creek, Cedar 
Creek Road, Forest Road 128, 5.1 miles northeast of 
Drake, 40.6603, -105.2902, 12 April 2014, B.C. 
Kondratieff, T.P. Belcher, 100+ ♂, 100+ ♀ (BYUC). 
Redstone Canyon, 40.5870, -105.2659, 24 January 
1986, B.C. Kondratieff, 12♂, 18♀ (CSUC). Tributary 
Spring Creek, Fort Collins, 40.5645, -105.1587, 15 
February 1986, B.C. Kondratieff, 12♂, 3♀ (CSUC). 
 
Male epiproct (n = 8). Length 468-528 μm, width at 
midlength 236-303 μm; greatest width slightly 
posterior to midlength. Body of epiproct bearing a 
pair of expansive median bulbs, forming convex 
ear-like lobes on either side of median groove near 
midlength (Figs. 1-2, 7, 11). Width across neck 91-
111 μm. Narrow median groove extends from 
posterior margin of posterior declivity to epiproct 
apex, becoming wider near apex (Figs. 2-5, 7, 9, 11). 
On either side of groove a cluster (12-24) of thick, 
spine-like setae occurs near origin of anterior 
declivity (Figs.1-5, 7-9, 11-12). Ventral epiproct 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 3 
 
 
 
 
Figs. 1-6. Arsapnia decepta male reproductive structures, Redstone Creek, Larimer Co., Colorado. 1. 
Abdominal terga 7-10. 2. Epiproct, dorsal. 3. Epiproct apex, dorsal. 4. Epiproct, lateral. 5. Epiproct, 
anterodorsal. 6. 7th tergal process, anterodorsal. (ad = anterior declivity; b = base; bs = basal strut; bu = bulb; 
ds = dorsal sclerite; n = neck; pd = posterior declivity; sc = setal spine cluster; tp7 = tergal process of segment 
7; vs = ventral sclerite). 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 4 
 
 
 
 
 
Figs. 7-12. Arsapnia decepta male reproductive structures, 7-10. tributary of Spring Creek, Larimer Co., 
Colorado, 11-12. Buckhorn Creek, Larimer Co., Colorado. 7. Abdominal terga 7-10. 8. Abdominal segments 
7-10, lateral. 9. Male, terminalia, dorsal. 10. 7th tergal process, anterodorsal. 11. Epiproct, dorsal. 12. Epiproct 
setal clusters. 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 5 
 
sclerite extends 40 μm beyond tips of outwardly 
hooked apices of dorsal sclerite (Figs. 3, 11). Lateral 
margins of epiproct slightly sinuate between bases 
of spine-like setae and apex (Figs. 2, 5, 9, 11); lateral 
aspect of epiproct (Figs. 4, 8) shaped somewhat like 
a duck head. 
Tergal process. A single, mound-shaped process on 
tergum 7 with dorsal margin entire  (Figs. 1, 6), or 
bearing a shallow dorsal concavity (Fig.10); lateral 
margins converging only slightly from anterior 
aspect; process bears lateral patches of small scale-
like structures. Width of process across anterior 
margin 172-231 μm; width greater than median 
height. 
Comments. The type locality of A. decepta, given as 
“Ft. Collins, Col.” by Banks (1897), remains an 
unspecified site. The specimens listed from 
“Redstone Canyon” in Larimer Co. were taken from 
a stream that forms part of the Big Thompson River 
drainage perhaps 5-7 km southwest of the Fort 
Collins city limits and the specimens listed from 
“tributary Spring Creek” were collected in the city 
limits of Fort Collins from a tributary which enters 
the Cache la Poudre River; we regard the latter 
group of specimens as topotypes for this species. 
Colleagues at Colorado State University have 
records of several hundred specimens collected 
from sites in Boulder, Douglas, Fremont, Jefferson, 
Larimer and Pueblo counties (pers. comm. B.C. 
Kondratieff), and Stark et al. (1973) reported the 
species (as Capnia barbata) from Littleton in 
Arapahoe Co. and from the Little Thompson River 
in Boulder Co. Most Colorado records that we have 
seen are from sites along the Front Range, but the 
next nearest sites where populations are known to 
occur are in the Sangre de Cristo Range of southern 
Colorado and northern New Mexico (B.C. 
Kondratieff, pers. comm.; Jacobi & Baumann 1983). 
The nearest sites to the Front Range where our 
specimens were collected are Eagle Creek and Rio 
Bonito in Lincoln Co., New Mexico. 
The epiproct of specimens from Gregory Creek, 
Boulder Co. have the greatest width (300-303 μm) 
of any specimens examined in the study and the 
length of all but two of the Front Range specimens 
exceeds the mean length for the entire sample 
(mean = 487.9 μm) (Tables 1-5, Figs. 1-3). The 
general shape of the apical third of the epiproct is 
intermediate between that of Rio Bonito specimens 
and those of Eagle Creek (Figs. 3, 51-54), however, 
they are more similar to the Eagle Creek specimens 
(Fig. 51) that share the longer, more exposed apex. 
 
 
Table 1. Epiproct and 7th tergal process characteristics for Colorado specimens of Arsapnia decepta. 
 
County Site 
Epiproct 
Length μm 
Epiproct  
Width μm 
# Left 
Setae  
# Right 
Setae  
T7 
Process μm 
Length/ 
Width Ratio 
Boulder Gregory  
Creek (n=2) 
524-527 300-303 17-18 17-20 188 1.74-1.75 
Larimer Buckhorn 
Creek (n=1) 
477 236 14 12 200 2.02 
Larimer Cedar  
Creek (n=2) 
468 257 14 14 172 1.82 
Larimer Redstone  
Canyon (n=2) 
525 285 19 24 198 1.86 
Larimer Tributary 
Spring Creek (n = 1) 
528 272 16 14 231 1.94 
 
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 6 
 
 
 
 
Figs. 13-18. Arsapnia decepta male reproductive structures, 13-15. Bear Canyon, Pima Co., Arizona, 16-18. 
Carr Canyon, Cochise Co., Arizona.13. Abdominal terga 7-10. 14. Epiproct, dorsal. 15. Setal spine clusters, 
dorsal. 16. Epiproct, dorsal. 17. Setal spine clusters, dorsal. 18. Epiproct, lateral. 
 
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 7 
 
 
 
 
Figs. 19-24. Arsapnia decepta male reproductive structures, 19-21. Rucker Creek, Chiricahua Mountains, 
Cochise Co., Arizona, 22-24. Cave Creek, Chiricahua Mountains, Cochise Co., Arizona. 19. Abdominal terga 
7-10. 20. Epiproct, dorsal. 21. Epiproct apex and setal spine clusters, dorsal. 22. Abdominal terga 7-10.  23. 
Epiproct dorsal. 24. Epiproct apex and setal spine cluster. 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 8 
 
Arizona Populations 
(Figs. 13-45) 
 
Material examined. USA: Arizona: Cochise Co., 
Cave Creek, Southwest Research Station, 
Chiricahua Mountains, 5400’, 31.8854, -109.2073, 3 
January 1972, V. Roth, 3♂, 1♀ (BYUC). Rucker 
Creek, Camp Rucker Campground, Chiricahua 
Mountains, 31.7615, -109.3695, 17 January 1984, 
R.W. Baumann, C.R. Nelson, 6♂, 2♀ (BYUC). Carr 
Creek, Carr Canyon, Huachuca Mountains, 34.4476, 
-110.2821, 17 January 1984, R.W. Baumann, C.R. 
Nelson, 7♂, 5♀ (BYUC). Coconino Co., Oak Creek, 
Hwy 89A, above junction of West Fork Oak Creek, 
35.0012, -111.7377, 20 January 1988, R.W. Baumann, 
B.C. Kondratieff, C.R. Nelson, B.J. Sargent, 20♂, 15♀ 
(BYUC). Gila Co., Christopher Creek, Hwy 260, 
Christopher Creek Campground, 34.3110, -111.0244, 
13 June 1974, B. Stark, 1♂, 1♀ (specimens from 
spider web, BPSC). Tonto Creek, above junction of 
Horton Creek, Upper Tonto Creek Campground, 
34.3235, -111.2924, 14 January 1984, R.W. Baumann, 
C.R. Nelson, 18♂, 14♀ (BYUC). Graham Co., Twilight 
Creek, Turkey Flat, Pinaleño Mountains, 32.6310, -
109.8187, 2 March 1984, C.R. Nelson, 3♂, 1♀ (BYUC). 
Mohave Co., Wheeler Spring, Hualapai Mountain 
Park, Pine Basin Area, near Kingman, 35.0850, -
113.8759, 20 January 1984, R.W. Baumann, C.R. 
Nelson, 28♂, 13♀ (BYUC). Pima Co., Bear Canyon 
Creek, Bear Canyon Campground, Santa Catalina 
Mountains, 32.3276, -110.7328, 19 January 1984, R.W. 
Baumann, C.R. Nelson, 14♂, 10♀ (BYUC). Santa Cruz 
Co., Gardner Creek, Santa Rita Mountains, 31.8258, -
110.7734, 17 January 1984, R.W. Baumann, C.R. 
Nelson, 9♂, 2♀ (BYUC).Yavapai Co., Lynx Creek, 
above Lynx Lake, near Prescott, 34.5145, -112.3812, 20 
January 1988, R.W. Baumann, C.R. Nelson, 4♂, 9♀ 
(BYUC). 
 
Table 2. Epiproct and 7th tergal process characteristics for Arizona specimens of Arsapnia decepta. 
 
County Site 
Epiproct  
Length μm 
Epiproct 
Width μm 
# Left 
Setae 
# Right 
Setae 
T7 
Process μm 
Length/ 
Width Ratio 
Cochise Cave Creek  
SWRS (n=1) 
478 239 20 20 229 2.00 
Cochise Carr Canyon 
(n=1) 
541 245 30 25 - 2.21 
Cochise Rucker Creek  
(n=1) 
462 248 27 25 - 1.86 
Coconino Oak Creek 
(n=1) 
578 278 27 29 - 2.08 
Gila Christopher Creek 
(n=1) 
459 265 15 16 172 1.73 
Gila Tonto Creek 
(n=2) 
511-524 260-263 23-27 24-28 - 1.95-2.00 
Graham Turkey Creek 
(n=1) 
524 247 28 28 - 2.12 
Mohave Wheeler Spring 
(n=2) 
561 256 20-28 18-24 - 2.19 
Pima Bear Canyon 
(n=1) 
549 262 31 34 194 2.09 
Santa Cruz Gardner Creek 
(n=2) 
438-452 200 18-22 20-26 - 2.19-2,29 
Yavapai Lynx Creek 
(n=1) 
511 263 26 30 - 1.94 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 9 
 
 
 
 
 
Figs. 25-30. Arsapnia decepta male reproductive structures. 25-27. Christopher Creek, Gila Co., Arizona 
(damaged). 28-30. Tonto Creek, Gila Co., Arizona. 25. Epiproct, dorsal. 26. Epiproct apex and setal spine 
clusters, dorsal. 27. 7th tergal process, anterodorsal. 28. Epiproct, dorsal. 29. Epiproct bulbs and setal spine 
clusters, oblique lateral. 30. Right setal cluster, posterodorsal. 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 10 
 
 
 
 
Figs. 31-36. Arsapnia decepta male reproductive structures. 31-33. West Fork Oak Creek, Coconino Co., 
Arizona, 34-36. Wheeler Spring, Hualapi Mountain Park, Mohave Co., Arizona. 31. Epiproct, dorsal. 32. 
Epiproct setal spine clusters, dorsal. 33. Epiproct, dorsolateral. 34. Epiproct, dorsal. 35. Epiproct setal spine 
clusters, dorsal. 36. Epiproct, dorsolateral.  
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 11 
 
Male epiproct (n = 14). Length 438-578 μm, width 
200-278 μm (Table 2). Shape and general structure 
similar to those of other populations examined 
(Figs. 13, 18, 19, 22, 33, 36, 39, 42, 45). Setal spines in 
clusters of 15-34 (Figs. 14-17, 20-21, 23-26, 28-32, 34-
35, 37-38, 40-41, 43-44). Neck width 100-144 μm 
(Figs. 11, 14, 16, 20, 23, 28, 31, 34, 37, 40, 43). 
Tergal process (n = 3). Tergum 7 bears a broad, 
sometimes mesally notched, dorsal process (Figs. 13, 19, 
22, 27), and tergum 6 bears a smaller mesal process on 
one specimen from the Chiricahua Mountains. 
Dorsolateral margins bearing a few knob-like scales. 
Width across anterior margin 172-229 μm. 
Comments. The first Arizona records for A. decepta 
are attributed to Jewett (1966) (as C. barbata), and 
Stewart et al. (1974) show plots of six sites (also as C. 
barbata) in five Arizona counties (Apache, Cochise, 
Gila, Pima, and Yavapai). Our specimens represent 
populations from eight counties (Cochise, 
Coconino, Gila, Graham, Mohave, Pima, Santa Cruz 
and Yavapai) and the following natural regions: the 
Mogollon Rim, Oak Creek Canyon and Yavapai 
Hills in central Arizona, the Hualapai Mountains in 
west central Arizona, and the Chiricahua, 
Huachuca, Pinaleño, Santa Catalina and Santa Rita 
Mountains in southeastern Arizona. Nelson & 
Baumann (1987a) provided SEM micrographs for 
specimens collected in Ramsey Canyon, Huachuca 
Mountains, Cochise Co., Arizona. 
This sample of Arizona specimens includes 
males with the three longest epiprocts (578 μm, Oak 
Creek Canyon; 561 μm, Wheeler Spring; 549 μm, 
Bear Canyon) in the entire sample, and all fell within 
the 95% confidence interval (247.2 ± 13.1 μm) in 
epiproct width. In addition, the 9 highest counts of 
setal spines per cluster (27-34) were recorded from 
these Arizona specimens. The greatest number of 
setal spines (31 left, 34 right) were recorded on a 
Bear Canyon (Pima Co.) specimen. 
 
Nevada Population 
(Figs. 46-48) 
 
Material examined. USA: Nevada: Clark Co., Deer 
Creek, Deer Creek Picnic Area, Hwy 158, Spring 
Mountains, near Las Vegas, 36.3144, -115.6212, 21 
January 1984, R.W. Baumann, C.R. Nelson, 1♂, 3♀ 
(BYUC).
 
 
Table 3. Epiproct and 7th tergal process characteristics for Nevada specimens of Arsapnia decepta. 
 
County Site 
Epiproct 
Length μm 
Epiproct 
Width μm 
# Left 
Setae 
# Right 
Setae 
T7 
Process μm 
Length/ 
Width Ratio 
Clark  Deer Creek 
(n=1) 
379 157 31 30 185 2.41 
 
 
Male epiproct (n = 1). Length 379 μm, width 157 μm 
(Table 3). Shape and general structure similar to 
those of other specimens, but smaller and with 
higher setal spine counts. Setal spines in clusters of 
30-31 located anterior of midlength and on either 
side of median groove (Figs. 46-48). Neck width 135 
μm. 
Tergal process. Tergum 7 bearing a broad dorsal 
process, 185 μm in width; dorsal margin concave; 
lateral prominences covered with small scale-like 
structures. 
Comments. The Spring Mountains represent the 
only known site where A. decepta specimens have 
been collected in Nevada (Nelson & Baumann 
1989). We examined a single male specimen from 
Deer Creek at its junction with Hwy 158. As Figs. 
46-48 and Tables 1-5 indicate, the epiproct of this 
specimen is shorter and more slender than other 
specimens examined, and also has one of the 
highest setal spine counts we encountered, 
second only to the Bear Canyon specimens from 
Arizona.
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 12 
 
 
 
 
Figs. 37-42. Arsapnia decepta male reproductive structures. 37-39. Gardner Creek, Santa Rita Mountains, 
Santa Cruz Co., Arizona. 40-42. Twilight Creek, Pinaleño Mountains, Graham Co., Arizona. 37. Epiproct, 
dorsal. 38. Epiproct setal spine clusters, dorsal. 39. Epiproct, dorsolateral. 40. Epiproct, dorsal. 41. Epiproct 
setal spine clusters, dorsal. 42. Epiproct, dorsolateral. 
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 13 
 
 
 
Figs. 43-48. Arsapnia decepta male reproductive structures. 43-45. Lynx Creek, Yavapai Co., Arizona. 46-48. 
Deer Creek, Spring Mountains, Clark Co., Nevada. 43. Epiproct, dorsal. 44. Epiproct setal spine clusters, 
dorsal. 45. Epiproct, dorsolateral. 46. Epiproct, dorsal. 47. Epiproct setal spine clusters, dorsal. 48. Epiproct, 
dorsolateral. 
 
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 14 
 
New Mexico Populations 
(Figs. 49-60) 
 
Material examined. USA: New Mexico: Catron Co., 
Leggett Canyon Creek, Leggett Canyon, Hwy 180, 
south of Luna, 33.7076, -108.8938, 13 January 1987, 
R.W. Baumann, B.C. Kondratieff, B.J. Sargent, 7♂, 
1♀ (BYUC). Grant Co., Gila River, Hwy 180, south 
of Cliff, 32.9451, -108.6069, 13 January 1987, R.W. 
Baumann, B.C. Kondratieff, B.J. Sargent, 1♂, 1♀ 
(BYUC). Lincoln Co., Eagle Creek, Rt. 532, south of 
Sierra Vista, 33.3925, -105.6885, 11 March 1996, B. 
Stark, 7♂, 5♀ (BPSC). Lincoln Co., Rio Bonito, below 
Bonito Lake, Bonito Lake Road, 33.4516, -105.6953, 
11 March 1996, B. Stark, 31♂, 37♀ (BPSC). 
 
Male epiproct (n = 12). Length 412-562 μm, width 
180-269 μm (Table 4). Shape and general structure 
as in other populations. Setal spines in clusters of 10-
21, located near midlength and on either side of 
median groove (Figs. 51, 54, 55-60). Neck width 105-
130 μm. 
Tergal process. Bearing a slight notch on the 
posteromedian margin (Fig. 49-52, 57-58), and with 
lateral margins moderately convergent. 
Dorsolateral lobes on either side of notch covered 
with conical tubercles. Width of process across 
anterior margin 100-192 μm. 
Comments. Arsapnia decepta has been reported (as 
Capnia decepta or C. barbata) from numerous sites in 
12 counties of New Mexico (Jacobi & Baumann 1983, 
Jacobi & Cary 1986, Jacobi & Cary 1996, Jacobi et al. 
2005). The collecting sites listed above include 
specimens from two streams that are in the Rio 
Hondo drainage in Lincoln Co. Despite the close 
proximity of these two sites, the epiprocts from 
Eagle Creek specimens are shorter and narrower 
than those from Rio Bonito (Table 4), but the Eagle 
Creek specimens have an apex that is longer and 
narrower than those from Rio Bonito (compare Figs. 
50 with 53, and 51 with 54). Among the specimens 
illustrated with micrographs (Figs. 49-54), the Eagle 
Creek specimens show asymmetrical setal spine 
counts of 10-17 left and 10-15 right (Table 4). The 
counts for both of these ranges are also the lowest 
observed for any A. decepta population. This could 
be related to the smaller epiproct size for Eagle 
Creek specimens, or may simply reflect the small 
sample size for all populations examined. As 
indicated in Table 4, epiproct size and setal spine 
counts for Catron and Grant county specimens are 
more similar to those from adjacent states than to 
the Eagle Creek specimens.
 
 
Table 4. Epiproct and 7th tergal process characteristics for New Mexico specimens of Arsapnia decepta. 
 
County Site 
Epiproct  
length μm 
Epiproct  
Width μm 
# Left 
Setae 
# Right 
Setae 
T7 
Process μm 
Length/ 
Width Ratio 
Catron Leggett 
Canyon Creek 
(n=1) 
562 269 17 21 - 2.08 
Grant Gila River 
(n=1) 
468 237 - 20 168 1.97 
Lincoln Eagle Creek 
(n=3) 
412-413 180-200 10-17 10-15 146-168 2.06-2.29 
Lincoln Rio Bonito 
(n=7) 
436-483 217-244 12-19 12-18 100-192 1.84-2.02 
 
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 15 
 
 
 
Figs. 49-54. Arsapnia decepta male reproductive structures. 49-51. Eagle Creek, Lincoln Co., New Mexico. 52-
54. Rio Bonito, Lincoln Co., New Mexico. 49. Abdominal terga 7-10. 50. Epiproct, dorsal. 51. Epiproct apex 
and setal spine clusters. 52. Abdominal terga 7-10. 53. Epiproct, dorsal. 54. Epiproct apex and setal spine 
clusters. 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 16 
 
 
 
 
Figs. 55-60. Arsapnia decepta male reproductive structures. 55-57. Leggett Canyon Creek, Catron Co., New 
Mexico. 58-60. Gila River, Grant Co., New Mexico. 55. Epiproct, dorsal. 56. Epiproct, dorsolateral. 57. 
Abdominal segments 7-10, lateral. 58. Epiproct and 7th tergal process, dorsal. 59. Right setal cluster, dorsal. 
60. Epiproct, dorsolateral. 
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 17 
 
Mexico Populations 
(Figs. 61-66) 
 
Material examined. MEXICO: Baja California: 
Arroyo La Corona, Sierra San Pedro Martir National 
Park, 16 January 1988, R.W. Baumann, B.C. 
Kondratieff, C.R. Nelson, B.J. Sargent, 1 pharate ♂ 
larva (dissected), 4♀, 4 larvae. Chihuahua: Cañon 
de Agua, Bowman Ranch, near Colonia Juarez, 22 
January 1987, B.C. Kondratieff, B.J. Sargent, T. 
Bowman, 2♂, 4♀ (BYUC). 
 
Male epiproct (n=2). Length not estimated due to 
specimen condition and orientation (Figs. 61, 64; 
Table 5). Width 238 μm. Shape and general features 
similar to other specimens examined. Setal spines in 
clusters of 13-18 (Table 5, Figs. 61-66). Neck width 
93 μm (Fig. 64). 
Tergal process. Not visible in available figures. 
Comments. Only two male specimens were 
available for SEM study (Table 5) including a 
pharate male collected in Baja California and 
dissected by B.C. Kondratieff from the larval skin. 
Unfortunately, only six SEM images were prepared 
due to specimen condition and orientation (Figs. 61-
66). Despite the poor condition and orientation of 
these specimens, their epiprocts display the same 
general shape and the typical setal spine clusters 
found among other populations. The Baja California 
population should be re-examined with molecular 
data and with a more complete set of morphological 
data, and compared with California specimens of A. 
coyote when suitable material is available. The 
epiproct of A. coyote is similar, but distinct from A. 
decepta morphologically (see Figs. 67-72), and 
Heinold et al. (2014) also support recognition of A. 
coyote as a valid species based on molecular barcode 
data. The Chihuahua population exhibits a narrow 
neck width (93 μm) more consistent with A. coyote, 
but with respect to epiproct width, the specimen is 
more similar to A. decepta.
 
 
Table 5. Epiproct and 7th tergal process characteristics for Mexican specimens of Arsapnia decepta. 
 
Mexican State Site 
Epiproct  
Length μm 
Epiproct 
Width μm 
# Left 
Setae 
# Right 
Setae 
T7 
Process μm 
Length/ 
Width Ratio 
Baja California Arroyo La Corona 
(n=1) 
- - 15 13 - - 
Chihuahua Cañon de Agua 
(n=1) 
- 238 18 15 157 - 
 
 
 
Arsapnia coyote (Nelson & Baumann) 
Coyote Snowfly 
(Figs. 67-72) 
 
Capnia coyote Nelson & Baumann, 1987b:487. Holotype 
♂, (United States National Museum), Little Rock 
Creek, Cooper Canyon Campground, San Gabriel 
Mountains, Los Angeles Co., California 
http://lsid.speciesfile.org/urn:lsid:Plecoptera.speciesfile.org:
TaxonName:4978 
Arsapnia coyote: Murányi, Gamboa & Orci, 2014:14 
http://lsid.speciesfile.org/urn.lsid:Plecoptera.speciesfile.org:
TaxonName:465452 
Material examined. USA: California: Los Angeles 
Co., Little Rock Creek, Cooper Canyon 
Campground, San Gabriel Mountains, 31 March 
1981, R.W. Baumann, J. Stanger, 3♂ (BYUC). San 
Bernardino Co., East Fork of West Fork before 
Mohave River above Silverwood Lake, 9 January 
1988, R.W. Baumann, C.R. Nelson, 1♂ (BYUC). 
 
Male epiproct (n = 2). Length 575-618 μm, width at 
midlength 223-236 μm, Body of epiproct expanded 
into convex ear-like lobes near midlength (Figs. 67, 
70). Width across neck 67-83 μm. Shape and 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 18 
 
 
 
 
 
Figs. 61-66. Arsapnia decepta male reproductive structures, 61-63. Arroyo La Corona, Sierra San Pedro Martir 
National Park, Baja California. 64-66. Cañon de Agua, Bowman Ranch, near Colonia Juarez, Chihuahua. 61. 
Epiproct, anterodorsal. 62. Epiproct, setal spine clusters, anterodorsal. 63. Epiproct, lateral. 64. Epiproct, 
dorsal. 65. Epiproct, oblique lateral. 66. Epiproct apex and setal spine clusters, dorsal. 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 19 
 
 
 
 
Figs. 67-72. Arsapnia coyote male reproductive structures. 67-69. Little Rock Creek, Los Angeles Co., 
California.70-72. Mohave River, San Bernardino Co., California. 67. Abdominal segments 7-10, dorsal. 68. 
Epiproct apex and setal spine clusters. 69. Epiproct, oblique lateral. 70. Abdominal segments 7-10, dorsal. 
71. Epiproct apex and setal spine clusters. 72. Epiproct apex, lateral. 
 
 
 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 20 
 
general structure similar to those of populations of 
A. decepta examined. Left side setal spines in clusters 
of 25-28, and 28-32 on the right. 
Tergal process (n = 2). Bearing a slight to moderate 
notch of posteromedian margin (Figs. 67-70). 
Dorsolateral lobes bearing patches of small conical 
tubercles. Width of process across anterior margin 
200-280 μm. 
Comments. Arsapnia coyote is presently considered 
an endemic to southern California and the sister 
species of A. decepta (Nelson & Baumann 1987b). The 
two species overlap in many morphological features 
including epiproct width and setal spine counts, 
however two of the three longest epiprocts among 
specimens studied are of this species, and the 
epiproct length/width ratios (2.58 and 2.61 
respectively, Table 6) for these two specimens are 
the highest observed. Nelson & Baumann (1987b) 
distinguished the two species, in part, by virtue of 
a flatter dorsal epiproct surface and smaller 
epiproct depth (compare Figs. 69 and 72 with Figs. 
4 and 18). Recently, Heinold et al. (2014) supported 
recognition of A. coyote as a distinct species based 
on their report of an average genetic divergence of 
1.9% between males of A. coyote and A. decepta. 
 
Table 6. Epiproct and 7th tergal process characteristics for California specimens of Arsapnia coyote. 
 
County Site 
Epiproct 
Length μm 
Epiproct 
Width μm 
# Left 
Setae 
# Right 
Setae 
T7 
Process μm 
Length/ 
Width Ratio 
Los Angeles Little Rock 
Creek (n =1) 
575 223 28 32 280 2.58 
San Bernardino Mohave 
River (n = 1) 
618 236 25 28 200 2.61 
 
DISCUSSION 
Arsapnia decepta is a common winter-emerging 
species of the Southwestern United States and 
adjacent areas of Mexico. Many populations exist in 
relative isolation, consequently significant variation 
in male reproductive structures occurs. Much of this 
variation centers around epiproct length, width and 
setal spine counts for the left and right epiproct 
clusters. Setal spine counts for left side clusters 
range from 10 to 31 and right side clusters range 
from 10 to 34 in our samples. The lowest counts 
occurred among three individuals from Eagle Creek 
and Rio Bonito, New Mexico with clusters of 23, 25 
and 25 total setal spines (10,13; 12,13; 10,15), and 
other relatively low counts were observed for 
Buckhorn Creek, Colorado (14,12), and Cedar 
Creek, Colorado (14,14). The highest setal spine 
counts were from Bear Canyon, Arizona (31,34) and 
Deer Creek, Nevada (31,30) specimens. Total setal 
spine counts ranged from 40-65 for Arizona 
specimens, 26-43 for Colorado specimens, and 23-35 
for New Mexico specimens. Arsapnia coyote setal 
spine counts (53-60) were within the range of 
Arizona A. decepta specimens. 
Arsapnia decepta epiprocts ranged from 379-578 
μm in length (mean = 487.9 ± 19.4), but seven of the 
eight longest epiprocts were from Arizona (524-578 
μm) or Colorado (525-528 μm). Only two of the New 
Mexico specimens had epiproct lengths greater than 
500 μm. The epiproct lengths for the two specimens 
of A. coyote we examined were 575 and 618 μm. 
These lengths exceeded all but one of the A. decepta 
specimens. The two species overlap in setal spine 
counts and in epiproct length, however the epiproct 
depth character noted by Nelson & Baumann 
(1987b, 1989), although not easily measured with 
SEM, appears to be a reliable morphological 
character for distinguishing A. decepta and A. coyote. 
This paper is not a revision or a complete 
geographical study of A. decepta and A. coyote as 
presently known. Instead it is an overview of 
specimens from states in the United States and 
Mexico where specimens have been selected that 
show variation in epiproct structure. Complete 
museum records of these species are not recorded 
and only those specimens that were used for SEM 
study are included. Thus, the inclusion of a map 
showing the complete geographical distributions of 
 
 
Baumann, R.W., and B.P. Stark 2017. Variation in the Epiproct of Arsapnia decepta Banks, 1897 (Plecoptera: Capniidae), with Comments 
on Arsapnia coyote (Nelson & Baumann 1987). Illiesia, 13(01):1-21. https://doi.org/10.25031/2017/13.01 
 
 
Illiesia – http://illiesia.speciesfile.org      Volume 13 – Number 1 – Page 21 
these species is left for zoographical studies in the 
future. 
 
ACKNOWLEDGEMENTS 
We appreciate Boris Kondratieff, Colorado State 
University, C. Riley Nelson, Brigham Young 
University, and B.J. Sargent for their assistance in 
collecting Arsapnia specimens. We also thank Boris 
for rearing the mature nymphs from Baja California, 
for the loan of specimens from the Colorado Front 
Range, and for help in locating references. We also 
thank Denise Mason for her assistance in preparing 
micrographs for specimens from Redstone Canyon, 
Colorado and Rio Bonito, New Mexico. 
 
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Submitted 10 March 2017, Accepted 7 April 2017, Published 1 
May 2017 
Hosted and published at the University of Illinois, Illinois 
Natural History Survey, Champaign, Illinois, U.S.A.