A KANSAS ENDANGERED SPECIES: The Scott Riffle Beetle

Last updated: 2 December 2004

Right: The Scott Riffle Beetle: Coleoptera: Elmidae: Optioservus phaeus White.  A live adult photographed using a Nikon 990 attached to a 10x eyepiece on an American Optical Dissecting Scope with two Nikon strobe flashes on TTL.  The beetles were placed in a shallow depression in a piece of sandstone in water taken from their habitat.  They were very active, and crawled around a lot, requiring constant adjustment to keep them in view.  These photos by Roy Beckemeyer.

On Nov. 2, 2004, a team was assembled by Bob Gress of the Great Plains Nature Center in Wichita, Kansas, to make an expedition to Scott State Park in Scott County, western Kansas, to photograph the Kansas Endangered Scott Riffle Beetle for a publication on Kansas Threatened and Endangered species.  Bob had obtained the required permit from the Kansas Dept. of Wildlife and Parks through Ken Brunson, and Bob and Stan coordinated the visit with Rick Stevens, Park manager.  The team was comprised of Bob Gress, Stan Roth, Kyle Gerstner, Ed Miller, Roy Beckemeyer.  Bob and Kyle took macrophotos and Roy took microphotos.  Note that this beetle is a protected species, and permits must be obtained from the Kansas Department of Wildlife and Parks for any work with the animal or in and around its habitat.

Photos of adult and larval Scott Riffle Beetles.  All photos are of live insects in water.  Adults and larvae are about 2.5 mm long.  Seven adults and 1 larva were collected for photographing.  All were returned to the water.  They were kept in well-oxygenated water from the spring.  Photos below taken with Nikon 990 digital camera and a dissecting microscope with 2 strobe flash units (Nikon SB-26 and Sb-28).  Photos copyright 2004 by Roy J. Beckemeyer.

Left, left below, and right: An adult Scott Riffle Beetle.  Light color at the base of the legs is caused by air bubbles clinging to the legs.  these beetles live under water, breathing through an air bubble trapped beneath the abdomen.

Right:  Structure of the adult Riffle Beetle with some nomenclature noted.  

(Click on photos for larger view.)

Left: A close up of the head and antennae of the Scott Riffle Beetle.

Right: A ventral view of the beetle.  After a brief flight period just after the adult beetle emerges, riffle beetles stay in the water and are entirely aquatic for the remainder of their lives.  The glistening surface on the beetle's abdomen is due to very fine, dense hair that traps air bubbles.   This "plastron" is the beetle's "diving bell", picking up oxygen through diffusion from the highly oxygenated water of the riffle as the beetle breathes.  

Left: Adult antennae - 11 segments, filiform.

Right: Microphotography set-up used to take these photos.  TTL flash with 2 separate strobes was used.  Battery packs supplemented the flash batteries so that pictures could be taken nearly continuously over a period of several hours.

Left and right: Dorsal views of the larva of the Scott Riffle Beetle.

Left: Lateral View of Scott Riffle Beetle larva.  Right: Ventral view.

Left: Some features of the Scott Riffle Beetle larva are annotated on this lateral view: the terminal gills, the "operculum" that covers them when they are retracted, and the abdominal and thoracic segmentation.

Right: An annotated version of the ventral view of the larva showing the characteristic features of the various pleurites on the thorax and abdomen used in keying out the larva to the genus Optioservus.

Left: The extended abdominal gills of the Scott Riffle Beetle larva.

References:

1. Brown, H. P., and D. G. Huggins, 1977, "Additions and corrections to the list of aquatic beetles of the families Dryopidae and Elmidae from Kansas", pp. 41-44 In R. Brooks (Ed.), New records of the fauna and flora of Kansas for 1976, Tech. Publ. No. 4 of the State Biol. Surv. of Kansas, Lawrence
2. Collins, J.T., S.L. Collins, J. Horak, D. Mulhern, W. Busby, C.C. Freeman, & G. Wallace, 1995, "An illustrated guide to endangered or threatened species in Kansas", Univ. Press of Kansas, Lawrence
3. Ferrington, L.C., Jr., 1985, "Population study of Optioservus phaeus White, a Riffle Beetle of Threatened Status endemic to Kansas,", Rept. No. 29, State Biol. Surv. of Kansas, Lawrence
4. Ferrington, L.C., Jr., W.H. Busby, and M.A. Blackwood, 1991, "Status report on Optioservus phaeus White (Scott Riffle Beetle)", Rept. No. 49, State Biol. Surv. of Kansas, Lawrence
5. Huggins, D. G., 1985, "Insects and their relatives", Chapter 5, pp. 115-128 In J. T. Collins (Ed.), Natural Kansas, University Press of Kansas, Lawrence [A paragraph on the Scott Riffle Beetle by Huggins and a delightful drawing of one by Linda Dryden may be found on p. 121]
6. Huggins, D. G., P. M. Liechti, and D. W. Roubik, 1976, "Species accounts for certain aquatic macroinvertebrates from Kansas, pp. 13-77 In J. Caldwell (Ed.), New records of the flora and fauna of Kansas for 1975, Tech. Publ. No. 1 of the State Biological Survey of Kansas, Lawrence
7. Layher, B., 2002, Draft Recovery Plan for the Scott Riffle Beetle, Optioservus phaeus Gilbert [sic, should be "White"], in Kansas, Kansas Dept. of WIldlife & Parks
8. White, D.S., 1978, "A revision of the nearctic Optioservus (Coleoptera: Elmidae) with descriptions of new species", Systematic Entomology, 3:59-74 
9. White, S.C., & G.A. Salsbury, 2000, Insects in Kansas, Third Edition, Kansas Department of Agriculture [See page 189 for a note and photograph of Ophioservus phaeus White]

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