Speaking of rare cave spiders

Just yesterday I posted about Empire Cave in Santa Cruz, California.  The drainage that surrounds Empire Cave is, as we know, the only known home of the Empire Cave spider.  It turns out that recent days have also seen the breaking of a story about another rare cave spider.

The Braken Bat Cave meshweaver (Cicurina venii) was rediscovered two weeks ago in the middle of a highway construction site in San Antonio, Bexar County.  The species had not been spotted since its initial discovery in 1980 in Braken Bat Cave, northwestern Bexar County.  This second discovery was only five miles from the original discovery site¹.  In 1990, someone was kind enough to build a housing development on top of the cave where the only known specimen had ever been collected.  In the process the entrance to the cave was filled in, and until two weeks ago the world did not know whether the spider had gone extinct².

Now humans have rediscovered this meshweaver while building an underpass on Texas 151, at Loop 1604. This time the government owned the land instead of some moron who would blithely kill off an entire genetic line, so the $15.1 million highway project has been suspended indefinitely.

The tiny cave where the new specimen was found was uncovered during construction activities.

Biologists have been working alongside construction crews from the start because this area is known for its abundance of natural resources, including songbirds and rare cave animals, like the spiders, said Stirling J. Robertson, biology team leader for TxDOT's environmental affairs division. 

To find a Braken Bat Cave meshweaver was a discovery of another kind altogether, akin to “stumbling on a new Galapagos Island in terms of the biological significance of the region,” said biologist Jean Krejca, Zara's president. 

After the spider was collected in a bottle, it was dissected for it to be identified, Krejca said. Collecting and killing an endangered species is allowed for that purpose if done by someone with a federal permit. No other spiders have been spotted in the hole where the one was found. . . . 

“From a conservation standpoint,” Robertson said, “this is an amazing coup.” 

The entire area where the Braken Bat Cave meshweaver was found (not be confused with Bracken Bat Cave near Garden Ridge) could be a spider habitat. 

Biologists have identified 19 cave features, which look like holes, while working on the underpass project. Spiders, not currently classified as endangered, were in five of those holes, which biologists will continue to analyze¹.

And that idiot who built a housing development on top of a critically endangered species?  No word from him, but I think someone ought to go fill in the entrance to his house.

Sources
1.   My San Antonio
2.   http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cicurina+venii

Endemic invertebrates of Empire Cave

No one knows why Cave Gulch, on the edge of the University of California Santa Cruz campus, is so heavily blessed with endemic species - species that are found nowhere else in the world.

But the cave-studded gulch encompasses the entire global range of no fewer than six species.  All six are invertebrates specially adapted to the limestone caves of this minor gulch.  I'm not sure, and to my knowledge no one is, why none of these species occurs elsewhere.  In fact, at least two of them are found exclusively in Empire Cave (or Porter Cave as it's known to UCSC students), the largest cave in the drainage.  I've visited this little jewel a couple times, and here is what I've seen with regards to rare species.

The Empire Cave spider (Meta dolloff) spins its feeble orb web in the twilight area of the cave in order to feed on the insects that live there.  These spiders look somewhat like giant black widows, except for their splotched abdomens¹.

The yellow-eyed ensatina (Ensatina eschscholtzii xanthoptica) is a subspecies of the ensatina salamander.  The yellow-eyeds are endemic to central California.  Their range is highlighted in yellow on this map from California Herps (my go-to source for information on reptiles and amphibians).  The ensatinas are adorable little salamanders that are members of the family Plethodontidae - lungless salamanders which breathe through their skin, which has to be constantly kept moist².  It is this fact which makes it so strange for wandering salamanders (Aneides vagrans) to be found hundreds of feet high in California's redwood canopy.  When scientists discovered them living happily there, they wondered how on earth the wandering salamanders, which also belong to the Plethodontid family, could stay moist in the tops of the tallest trees in the world.  It turns out that coast redwoods, Sequoia sempervirens, are giant "aquifers aloft."  They hold huge amounts of water in deep soil mats, in addition to the water they pump of from their roots and comb from the fog to feed themselves³.

Anyway, back to yellow-eyed ensatinas.  These beautiful little guys have grooves up and down their bodies, can be territorial, and are able to drop their tails to distract predators.  During breeding season (or rather seasons, as yellow-eyed ensatinas breed during Fall and Spring and sometimes Winter), males rub their bodies and heads against females in an elaborate courtship ritual.  Finally they drop a sperm capsule on the ground, which the female picks up with her cloaca and keeps until she decides the time is ripe to fertilize it.  At the end of the season, the female lays the eggs under bark, logs, or rocks (or maybe in a cave?) and lays three to 25 eggs.  She stays with them until they hatch.

My friends and I have found yellow-eyed ensatinas both above- and belowground.  We have not spotted any of the other five known endemics, but I will tell you about them if we do.

Sources

1.   The Natural History of the UC Santa Cruz Campus, edited by Tonya M. Haff, Martha T. Brown, and W. aaaaBreck Tyler

2.   California Herps

3.   The Wild Trees, by Richard Preston

San Francisco shrub protected

First of all, welcome to Epoch!  Here I will be posting news, information, and sightings relating to rare species!  Whether they are endangered, threatened, or just endemic to a small region of the planet, these species are made sacred by their scarcity.  I hope to photograph and describe these animals, plants and fungi, some of which are on the brink of disappearing from the universe forever.  My goal is to set up a space where we can all appreciate these treasures that Earth has given us.

Anyway, onto the exciting news:

A. h. franciscana is transplanted to a new safe home.

A San Francisco Bay Area shrub has been listed as federally endangered after being thought extinct and then rediscovered near the Golden Gate Bridge.

The Franciscan manzanita (Arctostaphylos hookeri franciscana), a subspecies of Hooker's manzanita, gained protection Wednesday under the Endangered Species Act.  Before being spotted near a construction site by a botanist in 2009, the shrub was thought to be extinct, its last stronghold having been bulldozed in 1947.  The plant's rediscovery was celebrated by officials and environmentalists.

“It was like all the lions in the wild were gone and we thought that there were none left . . . and suddenly someone finds a wild pair,” U.S. Fish and Wildlife Service spokeswoman Sarah Swenty said.

From the AP:

Officials have proposed about 300 acres around the city and the Presidio Trust, mostly on government park land, where the ground-hugging shrub can grow again. Swenty said that people have already started growing the plant again in the Presidio. 

Environmental groups say the native shrub is special because it has evolved to survive tough Bay Area conditions, including heavy fog that blocks sunlight and low nutrient, high metal soil. But groups say the plant couldn’t evolve to fight the bulldozers and development that brought it to the brink of extinction. 

“It’s an essential component of a very rare ecosystem that one flourished in San Francisco,” said Brent Plater, executive director of the Wild Equity Institute. 

The plant can also be found in botanic gardens, and hybrid descendants have been sold.

Although the quote from Ms. Swenty suggests that two specimens of this manzanita remain, the AP article seemed to suggest that just one was spotted and transplanted.  What I'm wondering is, how will these one or two individuals establish a diverse enough population?

The Presidio Trust sounds like a good place for a field trip . . .