A new species of flightless, winter-active dung beetle, Stenotothorax woodleyi (Coleoptera: Scarabaeidae), associated with shrub-steppe habitat in Washington state

2006·4 MB·

by  Richard S Zack

PROC. ENTOMOL. SOC. WASH.
108(1), 2006, pp. 45-50
A NEW SPECIES OF FLIGHTLESS, WINTER-ACTIVE DUNG BEETLE,
STENOTOTHORAX WOODLEYI (COLEOPTERA: SCARABAEIDAE),
ASSOCIATED WITH SHRUB-STEPPE HABITAT IN WASHINGTON STATE
RICHARD S. ZACK, CHRISTOPHOR N. LOONEY, AND ROBERT D. GORDON
(RSZ and CNL) James Entomological Collection, Department of Entomology, Wash-
ington State University, Pullman, WA 99164-6382, U.S.A. (e-mail: [email protected]);
(RDG) P.O. Box 65, Willow City, ND 58384 U.S.A. (e-mail: [email protected])
Abstract.4A new species of flightless beetle (Scarabaeidae), Stenotothorax woodleyi
Gordon, is described from the Hanford Nuclear Site located in south central Washington
State. Stenotothorax is a former subgenus of Aphodius. Stenotothorax woodleyi is sepa-
rated from the related species S. washtucna (Robinson). Notes on habitat and phenology
are presented.
Key Words: Scarabaeidae, Aphodius, Stenotothorax, new species, Hanford, Washington
State, flightless beetle
Numerous species of Aphoodius, and re- States government as a site for the produc-
lated genera, commonly referred to as dung tion of plutonium to be used in weapons
beetles, are found throughout eastern Wash- production, Hanford is currently adminis-
ington State. Many species can be collected tered by the Department of Energy for nu-
from the dung of domestic and wild ani- clear waste management, environmental
mals. Adults of several species are winter- restoration, and research and development.
active (Hatch 1971, Robinson 1938, Saylor Placing such a large tract of land virtually
1940); these winter active species are off limits to the public for over half a cen-
thought to be detritovores and usually are tury has preserved a shrub-steppe ecosys-
not found in association with dung (Gor- tem that has otherwise changed radically
don, unpublished data). throughout the remainder of the Columbia
Beginning in 1995 and continuing Plateau and presents a rare chance to study
through 2003, RSZ and CNL conducted an native insect communities.
extensive entomological survey of the Han- The Hanford Site consists of a steeply
ford Nuclear Site that is situated in the rising, northeastern facing slope (Rattle-
semi-arid Columbia Plateau Basin of south snake Ridge41,150 m) and extensive flats
central Washington State. For the purposes that slope gently from 500 to 150 m before
of the study discussed in this paper, pitfall they reach the Columbia River. Vegetation
traps were used and maintained from March is primarily a sagebrush-bitterbrush/Sand-
1998 through June 2000 and again from berg9s bluegrass-cheatgrass type; the gen-
April 2002 through April 2003 to sample eral habitat is referred to as shrub-steppe
sites. (Daubenmire 1970). Several small, perma-
The 1,450 km? of the Hanford Nuclear nent springs and associated riparian areas
Site were closed to the general public in are found in the southeastern portion of the
1943. Originally acquired by the United Site; this area is referred to as the Fitzner-
46 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
: |
Fig. 1. Schematic of pitfall trap. A, Trap receptacle. B, Cover. C, Baffles.
Eberhardt Arid Lands Ecology Area (ALE). depth of 2.5 cm with propylene glycol (Si-
For a discussion of the plants of Hanford, erra Brand®) diluted 1:1 with water. Traps
including all sites examined in these stud- were collected on an irregular basis de-
ies, see Sackschewsky et al. (1992) and pending on time of season (Table 1). A GPS
Downs et al. (1993). Climate at Hanford is reading for each site was taken at a trap
best characterized as semi-arid with hot and located in the approximate center of the trap
dry summers and cold winters. Precipita- line.
tion ranges from 30435 cm at the crest of Pitfall sites4Beetles were collected in
Rattlesnake Ridge to less than 12 cm in four of six survey sites established on that
central Hanford and along the Columbia portion of the Hanford Site south of the Co-
River. Temperatures range from an average lumbia River. Depending on site, traps were
of 3°C in January to 33°C in July; temper- maintained for one to two years.
atures of 32°C or above occur an average The ENE slope of Gable Mountain
of 56 days per year (ERDA 1975). (46°35.745'N, 119°26.3849'W4130 to 185
m) is a north-facing slope dominated by big
MATERIALS AND METHODS
sagebrush (Artemisia tridentata Nutt.),
Pitfall traps.4Traps consisted of 88one- cheatgrass (Bromus tectorum L.) and
pound= plastic deli cups with an 11.5 cm bunchgrasses in sandy soil. A series of 15
open top diameter and a depth of 8.25 cm. pit traps was placed 10 m apart running
Cups were buried flush with the soil. Each from an elevation of 130 m, which was ap-
trap was covered with an x-shaped set of proximately 20 m higher than the base of
runners with a span of 46 cm from the cen- the Mountain, to 185 m in elevation. The
ter of the trap; runners were 7.5 cm high. area 1s typical shrub-steppe.
A 30.5 cm square lid was placed over the The Rattlesnake Spring system
runners and was centered on the center of (46°30.447'N, 119°41.887'W4210 m) is
the cup (Fig. |). Runners and lids were cut situated in the northeast corner of ALE on
from sheet metal. Cups were filled to a the flat of Cold Creek Valley. This is the
VOLUME 108, NUMBER 1 47
most prominent, permanent spring on the
Hanford Site and flows approximately 3
km, beginning from ground seepage and
being fed by a number of smaller springs
along its course. The area surrounding the
spring is typical shrub-steppe, the soil being
very sandy. Five pit traps were placed at
various locations adjacent to the creek and
in the riparian zone.
A large area of sand dunes (46°31.369'N,
119°21.1929W4150 m) exists along the
western margin of the Columbia River and
several km inland. A series of 15 pitfall 3
traps was established in a T-shaped forma-
tion through the dunes habitat. Traps were
Figs. 2-3. Parameres. 2, Stenotothorax woodleyi.
placed 10 m apart with the transect running
3, S. washtucna.
through areas of dune with little to no veg-
etation and through a draw that contained
varying amounts of bitterbrush (Purshia tri- ate from anterior to posterior angle, partic-
dentata (Pursh) DC), sagebrush (Artemisia ularly strong explanate in apical %; base
spp.) and rabbitbrush (Chrysothamnus spp.) with marginal line lacking; surface with
along with varying numbers of low-grow- fine punctures separated by less than 3
ing plants. times a diameter except lacking in basal
Two sites were established at the eastern /\o. Elytron with striae feebly impressed,
end of the Fitzner-Eberhardt Arid Lands strial punctures nearly invisible; interval
Ecology Research area (ALE); these were with some scattered, fine punctures; humer-
in undisturbed shrub-steppe and in a dis- ous not dentate. Metasternum short, wing
turbed shrub-steppe habitat that had become not developed. Anterior tibial spur thick-
significantly invaded by _ cheatgrass ened, bent inward in apical %; inferior me-
(46°22.757'N, 119°31.0739'W4360 m). The sotibial spur short, curved inward in apical
adjacent sagebrush/Sandberg9s bunchgrass 143, Paramere as in Fig. 2.
and cheatgrass communities were divided Female: As for male except anterior tib-
by a one-lane road (15 m wide) that led to ial spur slender, inferior mesotibial spur
the summit of Rattlesnake Ridge. Ten pit- straight.
fall traps were placed in each habitat. Tran- Variation.4Length 7.25 to 9 mm, width
sects were begun 30 m from the road with 3.7 to 4.3 mm.
10 m of spacing between each trap. Type material.4Holotype: Washington,
ALE Site, Snively Basin, upper oldfield,
Stenotothorax woodleyi Gordon,
Hanford (AEC) Res., 10 mi. NW Richland,
new species
3-XII-1975, pit trap collection, Woodley
(Fig. 2) Collection. Allotype: Same data as holotype
Description.4Male: Length 8.60 mm, except date 1042641973, Lee Rogers Col-
width 4.25 mm. Form oval, widest behind lector. Paratypes: 12; with same data as ho-
middle of elytra, bases of pronotum and el- lotype except dates 10-26-1973, and 20-X-
ytra strongly constricted. Color dark red- 1975, Lee Rogers Collector; Washington,
dish brown to black throughout. Clypeus Benton Co., Richland, 14 Dec. 1981, on
granulate, anterior angle subangulate. Head snow; Wash., Benton Co., Hanford Site,
with frons and vertex densely, finely punc- ALE: tdi) up to Rattlesnake ~Mtn.,
tate. Pronotum with lateral margin explan- 46°22.751'N 119°31.073'W pitfall trap sur-
48 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
vey4No Fire Zone. The holotype, allotype, ferred to as the cadaverinus group of the
and seven paratypes are deposited in the genus Aphodius by American authors in-
National Museum of Natural History, cluding Saylor (1940) in his synopsis of the
Smithsonian Institution. Five paratypes are group. Schmidt (1913) proposed the formal
deposited in the M. T: James Entomological subgeneric name Stenotothorax for this
Collection, Washington State University. group along with subgeneric names for
Other specimens examined.4A total of nearly all units formerly known as groups.
750 other specimens were collected from This subgeneric classification was mostly
the Hanford Site (Table 1 and Results and ignored by authors dealing with American
Discussion). Most specimens are deposited species until relatively recently. Marco Del-
in the M. T. James Entomological Collec- lacasa (1988) and G. Dellacasa and Gordon
tion at Washington State University with (1994) used Stenotothorax in the subgener-
others deposited in the collections of The ic sense. Giovanni Dellacasa et al. (2001)
Nebraska State Museum, the University of elevated Stenotothorax to generic status,
Missouri, The California Academy of Sci- which is the classification followed here.
ences, and several private collections.
Distribution.4Known only from the RESULTS AND DISCUSSION
Hanford Site of south central Washington Stenotothorax woodleyi was taken from
State. four sites at Hanford but was only collected
Etymology.4The species is named for in significant numbers at the ALE shrub-
our friend and colleague, Norman Woodley, steppe and cheatgrass locations. Our find-
currently with the USDA, ARS, Systematic ings indicate that S. woodleyi may not be
Entomology Laboratory, at the Smithsonian sensitive to habitat changes typified by the
Institution. Norm collected the first known cheatgrass and sagebrush collecting sites. In
specimens during studies at the Hanford fact, S. woodleyi was found in most of the
Site in the 1970s. habitats that we sampled from the riparian
Biology.4Virtually unknown, but spe- zones of permanent springs to sand dunes,
cies of this genus are suspected detrito- albeit in small numbers.
vores. Stenotothorax washtucna (Robin- Table | lists dates and numbers of speci-
son), a closely related species, was taken mens taken during pitfall trapping in both
from the nests of the sagebrush vole (label the cheatgrass and sagebrush shrub-steppe
data). See additional remarks under Results sites on ALE. Between the period 24 Oct
and Discussion. and 17 Dec 1998, 302 of the 743 specimens
Remarks.4This species most closely re- collected were taken. Aside from this time
sembles S. washtucna and will key to cou- period, scattered specimens were collected
plet 15 in Saylor (1940) but has an entirely until the first week of May and, beginning
explanate lateral pronotal margin and com- again, in late Oct. No beetles were taken
pletely smooth pronotal base with no trace during the late spring or summer. Little is
of a basal marginal line. Stenotothorax known concerning the dispersal abilities of
washtucna has the lateral pronotal margin these flightless beetles or their normal pop-
not or only feebly explanate in the apical % ulation levels; however, information pre-
and pronotum with a basal marginal line at sented in Table | would indicate that the
least at middle of base. Male genitalia differ beetles are sensitive to trapping, and num-
principally in the parameral shape. The par- bers collected throughout the over two years
amers are bent downward apically in S. of continuous sampling may not be a true
woodleyi (Fig. 2) but are gently and evenly representation of the temporal distribution of
curved in S. washtucna (Fig. 3). this species. However, it is also possible that
The group of species to which S. wood- this odd capture pattern simply represents
leyi and S. washtucna belong has been re- the normal population density and variability
VOLUME 108, NUMBER 1 49
Table 1. Collection dates and number of captured specimens of Stenotothorax woodleyi from the Fitzner-
Eberhardt Arid Lands Ecology Reserve (ALE).
Cheatgrass Typical Shrub-Steppe
Collection Date Number Collection Date Number
28 Mar Apr 1998 | 24 Oct-20 Nov 1998 l
4-18 Apr 1998 | 20 Nov417 Dec 1998 145
25 Apr41 May 1998 l 17 Dec 1998-6 Jan 1999 82
24 Oct-20 Nov 1998 86 6-15 Jan 1999 6
20 Nov417 Dec 1998 al 15-29 Jan 1999 24
17 Dec 1998-6 Jan 1999 45 29 Jan46 Feb 1999 2
6-15 Jan 1999 12 6-12 Feb 1999 6
15-29 Jan 1999 16 12-19 Feb 1999 D,
29 Jan46 Feb 1999 12 19-26 Feb 1999 4
4
6-12 Feb 1999 2 26 Feb4S Mar 1999 7
12-19 Feb 1999 11 5-13 Mar 1999 3
19-26 Feb 1999 i7/ 13-19 Mar 1999 |
26 Feb45 Mar 1999 12 26 Mar42 Apr 1999 l
5-13 Mar 1999 aS 7414 May 1999 |
13-19 Mar 1999 24 Oct42 Nov 1999 |
19-26 Mar 1999 249 Nov 1999 2
26 Mar42 Apr 1999 9-18 Nov 1999 1
2-9 Apr 1999 18425 Nov 1999 10
9-16 Apr 1999 25 Nov 1999 23
24 Oct42 Nov 1999 25 Nov43 Dec 1999 13
2-9 Nov 1999 9-16 Dec 1999 15
9-18 Nov 1999 NMWNO NNNnN re 16-23 Dec 1999 4
18-25 Nov 1999 23-30 Dec 1999
25 Nov43 Dec 1999 30 Dec 1999-6 Jan 2000
3-9 Dec 1999 ARS 13-20 Jan 2000
9-16 Dec 1999 20-27 Jan 2000 WNdNN d
16-23 Dec 1999 NO 27 Jan43 Feb 2000 I
23-30 Dec 1999 3-10 Feb 2000 3
30 Dec 1999-6 Jan 2000 10-17 Feb 2000
6-13 Jan 2000 17-24 Feb 2000
13-20 Jan 2000 24 Feb42 Mar 2000
20-27 Jan 2000 2-9 Mar 2000
3-10 Feb 2000 9-16 Mar 2000
10-17 Feb 2000 16-23 Mar 2000
24 Feb42 Mar 2000 23-30 Mar 2000 KWNH e hO
16-23 Mar 2000 WHHNKeP NR
over the two years. Capture/recapture stud- Rattlesnake Springs.4A total of three
ies, as well as a more thorough investigation beetles were collected at Rattlesnake
into this beetle9s natural history, would begin springs. Collection dates and numbers of
to answer these questions. beetles are as follows (1999): 19-26 Feb
Other Hanford sites at which the beetle (1); 26 Feb45 Mar (2).
was collected include: Sand dunes.4A total of two beetles were
ENE slope of Gable Mountain.4A total collected at the sand dunes. Collection dates
of seven beetles were collected on the slope and numbers of beetles are as follows
of Gable Mountain. Collection dates and (1998-99): 24 Oct425 Nov (1); 13-19 Mar
numbers of beetles are as follows (1998499): (1).
24 Oct-25 Nov (1); 17 Dec46 Jan (2); 6 Jan4 Beginning in 2002, three survey sites
15 Jan (2); 15429 Jan (1); 6412 Feb (1). were established in the newly created Han-
50 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
ford Reach National Monument, which is of Energy, The Nature Conservancy of
primarily that portion of the Hanford Site Washington State, and the Bullitt Founda-
located north of the Columbia River and in- tion. Dennis Strenge, Pacific Northwest Na-
cludes the Wahluke and Saddle Mountain tional Laboratory, Richland, WA, was es-
Wildlife Refuges. These sites were sampled pecially valuable to us throughout this and
from April 2002 through April 2003. No S. other studies conducted at the Hanford Site.
woodleyi were collected in these traps dur-
LITERATURE CITED
ing the period of study.
Why no S. woodleyi were found during Daubenmire, R. 1970. Steppe vegetation of Washing-
studies on the Hanford Reach National ton. Washington Agricultural Experiment Station
Monument is problematic. The overall hab- Technical Bulletin 62, 131 pp.
Dellacasa, G. and R. D. Gordon. 1994. North Ameri-
itat is very much like that shrub-steppe
can genus-group taxa of Aphodiini and their type
found on the opposite side of the Columbia species (Coleoptera: Aphodiidae). Frustula Ento-
River. In fact, at least one of the areas col- mologica 17: 157-174.
lected on the Monument is in sight of an Dellacasa, G., P. Bordat, and M. Dellacasa. 2001. A
revisonal essay of world genus-group taxa of
area where a small number of beetles was
Aphodiinae (Coleoptera: Aphodiidae). Memorie
taken, a distance of approximately 8 km in
della Societa Entomologica Italiana 79: 14482.
direct line. It is interesting to speculate that Dellacasa, M. 1988. Contribution to a world-wide cat-
the river has hindered the dispersal of the alogue of Aegialiidae, Aphodiidae, Auloncnemi-
beetle and has kept it from moving north of dae, Termitotrogidae (Coleoptera: Scarabaeoidea).
the river, at least in this general area. Our Memorie della Societa Entomologica Italiana 120:
14455.
collections and some earlier Hanford Site
Downs, J. L., W. H. Rickard, C. A. Brandt, L. L. Cad-
collections conducted south of the river rep-
well, C. E. Cushing, D. R. Geist, R. M. Mazaika,
resent the only available specimens of S. L. E. Rogers, M. R. Sackschewsky, and J. J. Nu-
woodleyi. Several other species of Stena- gent. 1993. Habitat types on the Hanford Site:
tothorax (the cadaverinus group of Aphod- Wildlife and plant species of concern. PNL-8942,
Battelle-Pacific Northwest Laboratory, Richland,
ius) are found in eastern Washington but
Washington.
none are known to be sympatric on the
ERDA (Energy Research and Development Adminis-
Hanford Site with S. woodleyi. tration). 1975. Final Environmental Statement,
During the period of this study, we ex- Waste Management Operations. ERDAQ-1538,
amined large amounts of coyote, elk, and Vol. 2. Energy Research Development Adminis-
tration, Richland, Washington.
mule deer dung, both during the summer
Hatch, M. H. 1971. The Beetles of the Pacific North-
and winter months, without ever finding
west. Part V: Rhipiceroidea, Sternoxi, Phytopha-
specimens of S. woodleyi. A member of the ga, Rhynchophora, and Lamellicornia. University
cadaverinus species group, S. woodleyi is of Washington Press, Seattle, Washington, 662 pp.
probably a burrow-inhabiting detritovore Robinson, M. 1938. Studies in the Scarabaeidae. 1.
(Coleoptera), Transactions of the American Ento-
and does not occur in dung. At two differ-
mological Society 64: 107-115.
ent times, a total of six specimens were
Saylor, L. W. 1940. Synopsis of the cadaverinus group
found at the entrances to animal burrows at of the genus Aphodius with descriptions of three
the ALE sagebrush site. Specimens were new species (Coleoptera: Scarabaeidae). Proceed-
found at the entrances to burrows in the un- ings of the Biological Society of Washington 53:
99-104.
disturbed shrub-steppe, two at the entrance
Saskschewsky, M. R., D. S. Lindeen, J. L. Downs, W.
to one burrow and four at the entrance to
H. Rickard, and G. I Bird. 1992. Vascular plants
another in early-December 1998. of the Hanford Site. WHC-EP-0554, Westing-
house Hanford Company. Richland, Washington.
ACKNOWLEDGMENTS Schmidt, A. 1913. Erster Versuch einer Einteilung der
exotischen Aphodien in Subgenera und als An-
The Nature Conservancy funded this pro-
hang einige Neubeschreibungen. Archiv ftir Na-
ject with awards from the U.S. Department turgeschichte, Abtheilung A, 79: 117-178.