27

Springs types have been defined on the basis of their sphere of discharge by Springer and Stevens (2008), who described 12 active springs types and 13 geomorphologically-defined springs microhabitats. Many microhabitats with asso-ciated biological assemblages co-occur within some individual springs, greatly contributing to biodiversity and species packing (Hallam 2010). We define springs-dependent species (SDS) as those that require, or most often occur in, springs or springs-supported habitats during one or more phases of their life cycles. Some springs types support endemic (unique) taxa or other SDS, particularly limnocrene (pool- forming), mound-forming, helocrene (marsh-forming), and gushet springs (e.g., Spamer and Bogan 1994, Stevens and Meretsky 2008, Stevens and Polhemus 2008, Stevens and Bailowitz 2009). For example, several endemic subspecies of speckled dace (Rhinichthys osculus) and many pupfish (Cyprinodon spp.) are SDS, occurring in hillslope or limnocrene springs run-out channels, which are springs-supported habitats (Minckley 1973; Minckley and Unmack 2008). Rheocrene (in-channel) springs are somewhat less likely to support endemic or rare SDS due to increased flooding disturbance. In addition to springs type, several other factors influence species richness and the occurrence of SDS at springs, including: springs habitat area, isolation, and geomorphic complexity (Hallam 2010, Schaller 2013).SDS include a wide array of aquatic springs source biota [e.g., Hydrobiidae – most Pyrgulop-sis springsnails; many elmid riffle beetles; many stoneflies (Plecoptera); some freshwater amphi-pods and isopods (e.g., Socorro isopod - Thermo-sphaeroma thermophilum); and many cyprino-dontid pupfish], as well as wetland plant species (e.g., Orchidaceae – Epipactis gigantea heleborine orchid; Cyperaceae – Carex specuicola Navajo sedge; Asteraceae – Flaveria mcdougalii McDou-

gal’s flaveria; Primulaceae – Primula specuicola cave-dwelling primrose). More than 170 spe-cies of Pyrgulopsis springsnails are known from western North America, the majority of which occur at the sources of individual springs, and among which at least 17 are or have been consid-ered for listing as endangered species. Leopard frogs (Ranidae: Lithobates spp.) in the Southwest are commonly found at springfed cienegas, fens, and other helocrene and low gradient hillslope springs (Clarkson and Rorabaugh 1989). Nu-merous native fish species in the DLCC are SDS (Beckman 1952, Minckley 1973, Sublette et al. 1990, Sigler and Sigler 1996, Wallace and Zaro-ban 2013). We exclude as SDS those generalist species that occasionally (non-obligatorily) occur in springs-generated habitats, including non-na-tive crayfish and non-native fish. However, some generalist taxa occur obligatorily in springs in particular regions and such populations will be regarded as being conditionally SDS. For exam-ple: American Dipper (Cinclus mexicanus) nest virtually obligatorily in cool spring-supported streams when they nest at low elevations in the arid Southwest (Stevens et al. 1997); and north-ern water shews (Sorex palustris) may occur primarily along high elevation springfed streams and in wet meadows (Hoffmeister 1986).

2. SprIngS dEpEndEnt SpEcIES (SdS)

28

Springs-Dependent Species of Grand CanyonRotund Velvety Shore Bug(Hemiptera: OchteridaeOchterus rotundus Polhemus and Polhemus)

The rotund velvety shore bug is a small (4.5-5.5 mm long), oval-flattened predatory insect that lives on wet seeping moss walls at springs in the upper half of the Colorado River corridor. As a member of the order Hemiptera (true bugs, with sucking mouthparts), it is distantly related to water striders, backswimmers, water boatmen, kissing bugs, and bed bugs. The Pol-hemus brothers first collected it from Grand Canyon at tributary springs during their river trip in 1975, and we have subsequently found it at a few other springs from Buck Farm downstream to Royal Arch Creek.

O. rotundus is predatory, likely feeding on fly andother soft-bodied insect larvae that crawl around in the moss. It is quite cautious around humans, detecting approaching visitors and adroitly slipping into crevices out of sight until the danger has passed. Hence, it is very easily overlooked.

Its habitat—wet, near-vertical, dripping moss walls—is an ancient one that supports some of the most ancestral semi-aquatic insects on Earth. It is also often relatively protected from floods, which roar down the canyons but leap over falls, leavingthe mossy vertical backwalls unscathed.

This species is one of several Grand Canyon springs-dependent insects that are known from central and southern Mexico into Guatemala. This “Guatemala biogeographic connection” means that sometime in the past few thousands or millions of years, similar habitats existed, either in continuous connection or as “stepping stones” of habitat between Central America and Grand Canyon.

Herbert ‘s and Breviceps Giant Water Bugs(Hemiptera: BelostomatidaeAbedus herberti herberti Hidalgo and Abedus breviceps Stål)

These are two of three giant water bug species known from Grand Canyon, all of which occur in desert springfed streams, and all of which are aquatic predators. Herbert’s gi-ant water bug is found in lower Grand Can-yon in streams within the ancient drainage of the early Cenozoic “California River”, a river that flowed east and north across the northwestern corner of Arizona. Herbert’s giant water bug is widespread through the Southwest. In contrast, the abedus water bug is found only in a single stream in central Grand Canyon, the only population of that species on the southern Colorado Plateau. Behavioral observations on abedus water bugs in southern Ari-zona revealed that it senses on-coming flashfloods, and climbs out of the water and above the flood waters to avoid the scouring effects of summer floods.

Abedus breviceps

Abedus herberti

29

Four-spotted Saldid Shore Bug(Hemiptera: SaldidaeMicracanthia quadrimaculata (Champion)

This tiny shore bug is known in the United States only from a single alkaline spring in the Inner Gorge of Grand Canyon. It is a tiny predator, likely preying on soft-bodied inver-tebrates, such as fly larvae. It patrols steeply sloping bedrock faces, watching for prey and enemies. M. quadrimacu-lata is otherwise reported from Central America and is yet another example of the “Guatemala biogeographic connec-tion” in Grand Canyon.

Grand Canyon Masked Clubskimmer(Odonata: Libellulidae Brechmorhoga pertinax (Hagen)

This large, showy dragonfly was discovered in 2003 and the Grand Canyon population of masked club-skimmer dragonfly is the only breeding population in the United States. It lives along flowing springfed streams in Grand Canyon from Nankoweap down-stream to Stone Creek. Its larvae are predators, con-suming mayfly larvae and other soft-bodied stream invertebrates. The type specimen of masked clubskim-mer was collected in Central America, and prior to its discovery in Grand Canyon, this species was only known from two specimens that were thought to have blown into the US from Mexico. Thus, the Grand Can-yon population represents an extremely isolated popu-lation, and genetics analyses are being undertaken to determine whether the Grand Canyon population represents a new subspecies.

Apache Spiketail Dragonfly(Odonata: Codulegastridae Cordulegaster diadema diadema Selys)

The Apache spiketail dragonfly is the largest and one of the most brilliantly colored creatures on the Colorado Plateau: a jet black body with bright yellow banding, and enormous, startlingly brilliant blue eyes. One of two western species, the spiketails are particu-larly adapted to life in steep, narrow canyons. This spe-cies flies in mid- to late summer and into autumn, and adults are most often found close to montane springs. Females lay their eggs in mud at the water’s edge, often at springs sources. They remain in the larval stage for three years, growing to nearly 5 cm (2”) in length, and live in stream bottom mud. In 1917 Clarence Kennedy suggested that spiketail larvae likely wash downstream in floods over their multi-year larval lifetime, so start-ing life at the headwaters makes sense. Watch for these remarkable dragonflies in Deer Creek from August through October.

Photo courtesy of Arizona Dragonflies Website

30

Southwestern Viceroy Butterfly(Leptidoptera: Nymphalidae Limenitis archippus obsoleta W.H. Edwards)

In 1934, David Rockefeller, Sr., then a teenager, crossed Grand Canyon on a rim-to-rim hike on the first major entomological collecting expedition in Grand Canyon. Fortunately, he deposited specimens at Grand Canyon and at several other museums, includ-ing the American Museum of Natural History in New York. Mr. Rockefeller captured a southwestern vice-roy butterfly at Phantom Ranch, as well as a number of aquatic beetles (he went on to assemble the largest personal beetle collection in the world). However, the viceroy butterfly disappeared from Phantom Ranch, and for many decades was assumed to have been extir-pated from Grand Canyon. In the Southwest, viceroy butterflies are most often associated with coyote willow (Salix exigua), and that willow species may have been eliminated from lower Bright Angel Creek by flood-ing in the 1960s. Larry Stevens found viceroys living in Deer Creek Valley in 2009, confirming its continued existence in Grand Canyon. Look for it there around the willows in August and September.

In the eastern US the viceroy is renown as a Műllerian mimic of the bad-tasting monarch butter-fly (Danaus plexippus), but in the West it mimics the equally bad-tasting queen butterfly (Danaus gilippus).

Martin’s Nerthra(Hemiptera: GelastocoridaeNerthra martini Todd)

One of the strangest-looking springs bugs in the Southwest, this 1 cm (1/2”) semi-aquatic predator is

found in Grand Canyon only in the ancient path of the early Cenozoic “California River”, a river that flowed east and north across the northwestern corner of Ari-zona. Nerthra lives at the margin of springfed streams in the lower Canyon, where it feeds on damselfly larvae and other soft-bodied in-vertebrates. It is rarely seen, but is related to the toad bugs (Gelas-tocoris)—two species of diminutive but much cuter bugs that hop along the shore-lines of desert streams in Grand Canyon.

The Grand Canyon Wetsalts Tiger Beetle(Coleoptera: Carabidae/CicindelinaeCicindela hemorrhagica arizonae Wickham)

The Grand Canyon wetsalts tiger beetle is endemic to Grand Canyon. It is a bronze species with cream markings, and is reddish underneath. The adults are agile and found at the edge of springfed streams, such as Hermit Creek, in mid-summer. They sit upright, at-tentively searching for prey and enemies, but are easily alarmed and fly and hide when one approaches closer than about 1.5 meters. The larvae live in tunnels and lunge out at passing prey—mostly soft-bodied insects.

This subspecies occurs upstream to Cliff Dwellers Lodge, and downstream to the Virgin River, although the taxonomy of the downstream population is not clear. It was first discovered in Grand Canyon by Row-land Hayward and C.H. Townsend, who collected it in July 1892 near Hance’s in-canyon cabin site, and David Rockefeller, Sr. collected it at Phantom Ranch in 1934.

Photo courtesy of Tom Checknis

Springs-Dependent Species of Grand Canyon