Endangered and Threatened Wildlife and Plants; Proposal to List the Spruce-Fir Moss Spider as an Endangered Species

DEPARTMENT OF THE INTERIOR

50 CFR Part 17

RIN 1018-AC25

Endangered and Threatened Wildlife and Plants; Proposal to List

the Spruce-Fir Moss Spider as an Endangered Species

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: The Service proposes to list the spruce-fir moss spider

(Microhexura montivaga) as an endangered species under the Endangered

Species Act of 1973, as amended (Act). This spider is currently known

from four mostly small populations located in western North Carolina

and eastern Tennessee. The spider's damp high-elevation forest habitat

is deteriorating rapidly due primarily to air pollution and exotic

insects. The species' current low numbers also increase its

vulnerability to harm from other threats. Listing Microhexura montivaga

as an endangered species would provide protection under the Act.

DATES: Comments from all interested parties must be received by March

28, 1994. Public hearing requests must be received by March 14, 1994.

ADDRESSES: Comments and materials concerning this proposal should be

sent to the Field Supervisor, U.S. Fish and Wildlife Service, 330

Ridgefield Court, Asheville, North Carolina 28806. Comments and

materials received will be available for public inspection, by

appointment, during normal business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Mr. John Fridell at the above address

(telephone 704/665-1195, Ext. 225).

SUPPLEMENTARY INFORMATION:

Background

The spruce-fir moss spider was originally described by Crosby and

Bishop (1925) based on collections made from a site in western North

Carolina in 1923 (Coyle 1981). Only a few specimens were taken, and

little was known about the species until its rediscovery approximately

50 years later by Dr. Frederick Coyle (Western Carolina University,

Cullowhee, North Carolina) and Dr. William Shear (Hampden-Sydney

College, Hampden-Sydney, Virginia) (Coyle 1981). Microhexura montivaga

is one of only two species belonging to the genus Microhexura in the

family Dipluridae (Coyle 1981; Harp 1991, 1992). The other species in

the genus, M. idahoana, occurs only in the Pacific Northwest (Coyle

1981). Diplurids belong in the primitive suborder Mygalomorphae, which

are often popularly referred to as ``tarantulas'' (Harp 1991, 1992).

The genus Microhexura is the northernmost representative of the family

Dipluridae and is also one of the smallest of the mygalomorph spiders,

with adults measuring only 3.0 to 5.6 millimeters (roughly \1/4\ to \7/

16\ inch) (Coyle 1981). Coloration of M. montivaga ranges from light

brown to a darker reddish brown, and there are no markings on the

abdomen (Harp 1992). The carapace is generally yellowish brown (Harp

1992). The most reliable field identification characteristics for the

spruce-fir moss spider are a pair of very long posterior spinnerets and

the presence of a second pair of book lungs, which appear as light

patches posterior to the genital furrow (Harp 1992).

The typical habitat of the spruce-fir moss spider is found in well-

drained moss (and liverwort) mats growing on rocks or boulders, in

well-shaded situations in mature, high-elevation Fraser fir (Abies

fraseri) and red spruce (Picea rubens) forests (Coyle 1981, Harp 1992).

The moss mats cannot be too dry (the species is very sensitive to

desiccation) or too wet (large drops of water can also pose a threat to

the spider) (Harp 1992). The spider constructs its tube-shaped webs in

the interface between the moss mat and rock surface (Coyle 1981, Harp

1992), though occasionally the web extends into the interior of the

moss mat (Harp 1992). The tubes are thin-walled and typically broad and

flattened with short side branches (Coyle 1981, Harp 1992). There is no

record of prey having been found in the webs of the spruce-fir moss

spider nor has the species been observed taking prey in the wild, but

the abundant springtails (collembolans) in the moss mats provide the

most likely source of food for the spider (Coyle 1981, Harp 1992).

Males of the species mature during September and October, and

females are known to lay eggs in June. The egg sac is thin-walled and

nearly transparent, and it may contain seven to nine eggs. The female

remains with the egg sac and, if disturbed, will carry the egg sac with

her fangs. Spiderlings emerge in September (Coyle 1981). The means of

dispersal of the spiderlings from the parental moss mat is not known,

but ``ballooning,'' a process by which the spiders use a sheet of silk

played out into the wind to carry them into the air, has been suggested

as a possible means of long-range dispersal (Harp 1992). The life span

of the species is also unknown, but Coyle (1981) estimated that it may

take 4 years for the species to reach maturity.

From 1989 through 1992, status surveys were conducted for the

spruce-fir moss spider (Harp 1991, 1992). Based on the results of these

surveys, the spider is presently known to exist at only four

locations--three sites in North Carolina and one in Tennessee. Of the

four remaining populations, only one appears to be relatively stable.

This population is located along the Avery/Caldwell County line in

North Carolina. The other two populations in North Carolina are located

in Swain County. Both of these Swain County populations are extremely

small, with only one spruce-fir moss spider having been found at each

of these two sites in recent years (Harp 1991, 1992). The spruce-fir

forests at these two Swain County sites are rapidly declining. The

Tennessee population is located in Sevier County. This population was

considered healthy in 1989 but is currently believed to be declining in

numbers and is endangered by habitat loss/alteration (Harp 1992). The

high-elevation spruce-fir forests throughout much of the species'

historic range are being decimated by the balsam wooly adelgid (Adelges

piceae), an exotic insect pest, and possibly by air pollution (acid

precipitation) and other factors not yet fully understood. The death

and thinning of the forest canopy results in locally drastic changes in

microclimate, including increased temperatures and decreased moisture

leading to desiccation of the moss mats on which the spruce-fir moss

spider, and possibly its prey base, depend for survival.

The spruce-fir moss spider is not included in the Service's notice

of review for animal candidates published in the Federal Register of

November 21, 1991 (56 FR 58804). However, because of concerns expressed

by some individuals for the spider's status, the Service contracted in

1990 for a survey of both historic and potential habitat of the

species. The results of the survey, which was completed in 1992,

indicate that the spider is undergoing a rapid decline in distribution.

Presently only one relatively stable population is known to survive,

and while currently considered to be healthy, this population is

potentially threatened by the same factors that are believed to have

resulted in the decline and/or extirpation of the species elsewhere

within its historic range.

Species appearing in the candidate notices of review are assigned

to either category 1, 2 or 3. In conjunction with the current proposed

rule, the Service has approved the spruce-fir moss spider as a category

1 candidate. Category 1 represents those species for which the Service

has enough substantial information on biological vulnerability and

threats to support proposals to list them as endangered or threatened

species.

The Service has met and been in contact with various Federal and

State agency personnel and private individuals knowledgeable about the

species concerning its status and the need for the protection provided

by the Act. On December 31, 1992, the Service notified appropriate

Federal, State, and local government agencies and landowners, in

writing, that a status review was being conducted and that the species

might be proposed for Federal listing. A total of ten written comments

were received. The National Park Service, the North Carolina Division

of Parks and Recreation, and three private individuals (including the

owner of the site containing the Avery/Caldwell County, North Carolina,

population) expressed strong support for the potential listing of the

spruce-fir moss spider as an endangered species. The U.S. Soil

Conservation Service, Tennessee Wildlife Resources Agency, Tennessee

Department of Environment and Conservation, Tennessee Valley Authority,

and the North Carolina Department of Agriculture stated that they had

no new or additional information on the species or threats to its

continued existence. No negative comments were received.

Summary of Factors Affecting the Species

Section 4(a)(1) of the Endangered Species Act (16 U.S.C. 1531 et

seq.) and regulations (50 CFR part 424) promulgated to implement the

listing provisions of the Act set forth the procedures for adding

species to the Federal lists. A species may be determined to be an

endangered or threatened species due to one or more of the five factors

described in Section 4(a)(1). These factors and their application to

the spruce-fir moss spider (Microhexura montivaga) are as follows:

A. The Present or Threatened Destruction, Modification, or Curtailment

of Its Habitat or Range

The spruce-fir moss spider is known to be endemic only to high-

elevation spruce-fir forests of western North Carolina and eastern

Tennessee. Historically, the species has been reported from four sites

in North Carolina and one in Tennessee. In North Carolina the species

has been recorded from two sites in Swain County, one in Yancey County,

and one in Avery and Caldwell Counties (Coyle 1981, Harp 1992). In

Tennessee, the species is known from only one site in Sevier County

(Coyle 1981).

During 1989 and through 1992, both historic and potential habitat

of the species was surveyed (Harp 1991, 1992). No new populations of

the spruce-fir moss spider were discovered, and of the five previously

recorded populations, only one--the Avery and Caldwell County, North

Carolina, population--appears to be stable (Harp 1992).

The Yancey County, North Carolina, population appears to have been

extirpated, and only a single individual could be found at each of the

two sites in Swain County, North Carolina (Harp 1992). The population

in Sevier County, Tennessee, was surveyed in 1989 and was considered to

be relatively healthy at that time (Harp 1991). However, revisits to

this site in 1992 indicated the population level is declining,

apparently in conjunction with a rapid decline in the forest canopy

occurring at the site and associated desiccation of moss-mat habitat

(Harp 1992).

The spruce-fir moss spider is very sensitive to desiccation and

requires situations of high and constant humidity (Coyle 1981; Harp

1991, 1992). Loss of forest canopy leading to increased light and

decreased moisture on the forest floor (resulting in desiccation of the

moss mats) appears to be the major cause for the loss and decline of

the spruce-fir moss spider at all four of these sites and the major

threat to the species' continued existence. In a 1991 letter to Keith

Langdon (National Park Service, Great Smoky Mountains National Park),

Dr. Frederick Coyle (Western Carolina University) indicated that the

spruce-fir moss spider was common at one of the sites in Swain County,

North Carolina, as late as 1983 but was extremely rare by 1988. In his

letter to Keith Langdon, Dr. Coyle stated that many of the moss mats at

this site had become dry and loose, which he suspected was due largely

to deterioration of the forest canopy at the site. Fraser firs at all

four of these sites (the Swain and Yancey County sites in North

Carolina and the Sevier County, Tennessee, site) have suffered

extensive mortality, believed to be primarily due to infestation by the

balsam wooly adelgid (J. Harp, Oak Ridge National Laboratory, personal

communication, 1993), a nonnative insect pest believed to have been

introduced into the United States from Europe (Eager 1984).

Atmospheric deposition of pollutants, primarily affecting the red

spruce (Harp 1992), may also be a major factor (either directly or

indirectly) in the decline of the forest canopy at these sites. It has

been estimated that the red spruce at the site in Yancey County, North

Carolina, where the species is now believed to be extirpated, have lost

75 to 90 percent of their foliage (Krahl-Urban et al. 1988), possibly

due to acid precipitation. The death and thinning of the canopy trees

within these stands also cause the remaining trees to be more

susceptible to wind and other storm damage, which has become a major

concern at the Sevier County, Tennessee, site (J. Harp, personal

communication 1992).

The spruce-fir forest at the site harboring the Avery/Caldwell

County, North Carolina, population of the spruce-fir moss spider has

not experienced the degree of decline that has occurred (and is

occurring) at the other sites known to support (or to have supported)

populations of the spider. However, the same factors that are believed

to have resulted in the decline of the spruce-fir forest and the

associated loss of suitable moss-mat habitat at these other sites

potentially threaten this population and its habitat at this site as

well.

B. Overutilization for Commercial, Recreational, Scientific, or

Educational Purposes

The spruce-fir moss spider is not currently known to be

commercially valuable; however, because of its extreme rarity and

uniqueness, it is conceivable that it could be sought by collectors. It

is one of only two members of the genus Microhexura, it is the only

representative of the primitive family Dipluridae in eastern North

America, and it is one of the smallest of the world's ``tarantulas.''

While collecting or other intentional take is not presently identified

as a factor contributing to the species' decline, the low numbers, slow

reproductive rate, and extremely restricted range of the spruce-fir

moss spider make it unlikely that the species could withstand even

moderate collecting pressure.

C. Disease or Predation

It is presently unknown whether disease or predation have played a

role in the decline of the spruce-fir moss spider. Further research is

needed in this area. While predation is not thought to be a significant

threat to a healthy population of the spruce-fir moss spider, it could

limit the recovery of the species or contribute to the local

extirpation of populations already depleted by other factors. Possible

predators of the spruce-fir moss spider include pseudoscorpions,

centipedes, and other spiders (Harp 1992).

D. The Inadequacy of Existing Regulatory Mechanisms

Neither the State of North Carolina nor the State of Tennessee

include arachnids on their lists of endangered and threatened species;

therefore, the species is unprotected in both States. Federal listing

would provide protection for the spruce-fir moss spider throughout its

range by requiring Federal permits to take the species and by requiring

Federal agencies to consult with the Service when activities they fund,

authorize, or carry out may affect the species.

E. Other Natural or Manmade Factors Affecting its Continued Existence

Only one of the four remaining populations of this species appears

stable. The other three surviving populations are extremely small, and

all four populations are geographically isolated from one another.

Therefore, the long-term genetic viability of these populations is in

doubt. Also, the restricted range of each of the surviving populations

makes them extremely vulnerable to extirpation from a single event or

activity, such as a severe storm, fire, land-clearing or timbering

operation, pesticide/herbicide application, etc. Because they are

isolated from one another, natural repopulation of an extirpated

population would be unlikely without human intervention.

The Service has carefully assessed the best scientific and

commercial information available regarding the past, present, and

future threats faced by this species in determining to propose this

rule. Based on this evaluation, the preferred action is to list the

spruce-fir moss spider (Microhexura montivaga) as an endangered

species. The species has been greatly reduced in numbers throughout the

majority of its historic range and presently is known to occur at only

four locations. At two of these locations, only lone individuals--one

at each location--have been observed in recent years; at a third

location the species has undergone a rapid decline in numbers and is

endangered by further habitat degradation/alteration. Only one of the

remaining populations appears to be stable at this time, and it is

potentially threatened by many of the same factors that are believed to

have resulted in the extirpation or decline of the other historically

known populations. Due to the species' history of population loss and

decline and the extreme vulnerability of the surviving populations,

endangered status appears to be appropriate for this species. Critical

habitat is not being proposed for this species at this time for the

reasons discussed below.

Critical Habitat

Section 4(a)(3) of the Act, as amended, requires that, to the

maximum extent prudent and determinable, the Secretary propose any

habitat of a species that is considered to be critical at the time the

species is proposed to be endangered or threatened. The Service's

regulations [50 CFR 424.12(a)(1)] state that designation of critical

habitat is not prudent when one or both of the following situations

exist: (1) The species is threatened by taking or other activity and

the identification of critical habitat can be expected to increase the

degree of threat to the species or (2) such designation of critical

habitat would not be beneficial to the species. The Service finds that

designation of critical habitat is not prudent for this species. Such a

determination would result in no known benefit to the spruce-fir moss

spider, and designation of critical habitat could further threaten the

species.

Section 7 of the Endangered Species Act requires that Federal

agencies insure that their actions are not likely to jeopardize the

continued existence of listed species, or result in the destruction or

adverse modification of critical habitat. (See the ``Available

Conservation Measures'' section for a further discussion of Section 7.)

As part of the development of this proposed rule, Federal and State

agencies were notified of the spider's general distribution, and they

were requested to provide data on proposed Federal actions that might

adversely affect the species. No specific projects were identified.

Should any future projects be proposed in areas inhabited by the

spruce-fir moss spider, the involved Federal agency will already have

the general distribution data needed to determine if the species may be

impacted by their action. If needed, more specific distribution

information would be provided.

Three of the four surviving populations of the spruce fir moss

spider are considered to be extremely small, and suitable habitat at

each of the four sites still supporting the species is very limited.

The precarious status of the species means that any Federal action with

the potential to result in significant adverse modification or

destruction of the species' habitat would also likely jeopardize its

continued existence. Under these conditions, no additional protection

for the spruce-fir moss spider would accrue from critical habitat

designation that would not also accrue from listing the species.

Consequently, when listed, habitat protection for the spruce-fir moss

spider will be accomplished through the Section 7 jeopardy standard and

Section 9 prohibitions against take.

In addition, the spruce-fir moss spider is very rare and unique,

and taking for scientific purposes and private collection could pose a

threat if specific site information was released. The publication of

critical habitat maps in the Federal Register, local newspapers, and

other publicity accompanying critical habitat designation could

increase the collection threat. The locations of populations of these

species have consequently been described only in general terms in this

proposed rule. Any existing precise locality data would be available to

appropriate Federal, State, and local government agencies from the

Service office described in the ``ADDRESSES'' section; from the

Service's Raleigh Field Office, P.O. Box 33726, Raleigh, North Carolina

27636-3726; the Service's Cookeville Field Office, 446 Neal Street,

Cookeville, Tennessee 38501; and from the North Carolina Wildlife

Resources Agency, North Carolina Natural Heritage Program, Tennessee

Wildlife Resources Agency, and Tennessee Department of Environment and

Conservation.

Available Conservation Measures

Conservation measures provided to species listed as endangered or

threatened under the Act include recognition, recovery actions,

requirements for Federal protection, and prohibitions against certain

practices. Recognition through listing encourages and results in

conservation actions by Federal, State, and private agencies, groups,

and individuals. The Act provides for possible land acquisition and

cooperation with the States and requires that recovery actions be

carried out for all listed species. The protection required of Federal

agencies and the prohibitions against taking and harm are discussed, in

part, below.

Section 7(a) of the Act requires Federal agencies to evaluate their

actions with respect to any species that is proposed or listed as

endangered or threatened and with respect to its critical habitat, if

any is being designated. Regulations implementing this interagency

cooperation provision of the Act are codified at 50 CFR Part 402.

Section 7(a)(4) requires Federal agencies to confer informally with the

Service on any action that is likely to jeopardize the continued

existence of a proposed species or result in the destruction or adverse

modification of proposed critical habitat. If a species is subsequently

listed, Section 7(a)(2) of the Act requires Federal agencies to ensure

that activities they authorize, fund, or carry out are not likely to

jeopardize the continued existence of such a species or to destroy or

adversely modify its critical habitat. If a Federal action may affect a

listed species or its critical habitat, the responsible Federal agency

must enter into consultation with the Service. The Service has notified

Federal agencies that may have programs which could affect the species.

Federal activities that could occur and impact the species include, but

are not limited to, the carrying out or issuance of permits for

construction, recreation or development actions that could result in

the loss or thinning of the high-elevation forest canopy, and pesticide

or herbicide applications for the control of noxious insects or weeds.

It has been the experience of the Service, however, that nearly all

Section 7 consultations have been resolved so that the species has been

protected and the project objectives have been met.

The Act and implementing regulations found at 50 CFR 17.21 set

forth a series of general prohibitions and exceptions that apply to all

endangered wildlife. These prohibitions, in part, make it illegal for

any person subject to the jurisdiction of the United States to take

(includes harass, harm, pursue, hunt, shoot, wound, kill, trap, or

collect; or to attempt any of these), import or export, ship in

interstate commerce in the course of commercial activity, or sell or

offer for sale in interstate or foreign commerce any listed species. It

also is illegal to possess, sell, deliver, carry, transport, or ship

any such wildlife that has been taken illegally. Certain exceptions

apply to agents of the Service and State conservation agencies.

Permits may be issued to carry out otherwise prohibited activities

involving endangered wildlife species under certain circumstances.

Regulations governing permits are at 50 CFR 17.22 and 17.23. Such

permits are available for scientific purposes to enhance the

propagation or survival of the species and/or for incidental take in

connection with otherwise lawful activities. In some instances, permits

may be issued during a specified period of time to relieve any undue

economic hardship that would be suffered if such relief were not

available. Such permits are not expected for the spruce-fir moss spider

since the species is not in trade.

Public Comments Solicited

The Service intends that any final action resulting from this

proposal will be as accurate and as effective as possible. Therefore,

comments or suggestions from the public, other concerned government

agencies, the scientific community, industry, or any other interested

party concerning this proposed rule are hereby solicited. Comments

particularly are sought concerning:

(1) Biological, commercial trade, or other relevant data concerning

any threat (or lack thereof) to this species;

(2) The location of any additional populations of this species and

the reasons why any habitat should or should not be determined to be

critical habitat as provided by Section 4 of the Act;

(3) Additional information concerning the range, distribution, and

population size of this species; and

(4) Current or planned activities in the subject area and their

possible impacts on this species.

Final promulgation of the regulation on the spruce-fir moss spider

will take into consideration the comments and any additional

information received by the Service, and such communications may lead

to a final regulation that differs from this proposal.

The Endangered Species Act provides for a public hearing on this

proposal, if requested. Requests must be received within 45 days of the

date of publication of the proposal. Such requests must be made in

writing and should be addressed to the Field Supervisor, U.S. Fish and

Wildlife Service, Asheville Field Office, 330 Ridgefield Court,

Asheville, North Carolina 28806.

National Environmental Policy Act

The Fish and Wildlife Service has determined that an Environmental

Assessment, as defined under the authority of the National

Environmental Policy Act of 1969, need not be prepared in connection

with regulations adopted pursuant to Section 4(a) of the Act. A notice

outlining the Service's reasons for this determination was published in

the Federal Register on October 25, 1983 (48 FR 49244).

References Cited

Coyle, F. A. 1981. The Mygalomorph Genus Microhexura (Araneae,

Dipluridae). Bull. Amer. Mus. Nat. Hist. 170:64-75.

Crosby, C. R., and S. C. Bishop. 1925. Two New Spiders From the Blue

Ridge Mountains of North Carolina (Araneina). Ent. News. 36:142-146,

Figures 1 and 2.

Eager, C. 1984. Review of the Biology and Ecology of the Balsam

Wooly Aphid in Southern Appalachian Spruce-fir Forests. IN: P.S.

White (ed.), The Southern Appalachian Spruce-Fir Ecosystem: Its

Biology and Threats. Research/Resources Management Report SER-71.

U.S. Dept. of Interior, National Park Service.

Harp, J. M. 1991. Status of the Spruce-fir Moss Spider, Microhexura

montivaga Crosby and Bishop, in the Great Smoky Mountains National

Park. Unpubl. report to the National Park Service, U.S. Department

of the Interior. 12 pp. plus appendix.

________. 1992. A Status Survey of the Spruce-fir Moss Spider,

Microhexura montivaga Crosby and Bishop (Araneae, Dipluridae).

Unpubl. report to the North Carolina Wildlife Resources Commission,

Nongame and Endangered Wildlife Program, and the U.S. Fish and

Wildlife Service, Asheville, North Carolina. 30 pp.

Krahl-Urban, B., H.E. Papke, K. Peters, and C. Shimanski. 1988.

Forest Decline. U.S. Environmental Protection Agency and German

Ministry of Research and Technology, 137 pp.

Author

The primary author of this proposed rule is John A. Fridell, U.S.

Fish and Wildlife Service, Asheville Field Office, 330 Ridgefield

Court, Asheville, North Carolina 28806 (704/665-1195, Ext. 225).

List of Subjects in 50 CFR Part 17

Endangered and threatened species, Exports, Imports, Reporting and

recordkeeping requirements, and Transportation.

Proposed Regulation Promulgation

Accordingly, the Service hereby proposes to amend part 17,

subchapter B of chapter I, title 50 of the Code of Federal Regulations,

as set forth below:

PART 17--[AMENDED]

1. The authority citation for part 17 continues to read as follows:

Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.

4201-4245; Public Law 99-625, 100 Stat. 3500; unless otherwise

noted.

2. Sec. 17.11(h) is amended by adding the following, in

alphabetical order, under ARACHNIDS, to the List of Endangered and

Threatened Wildlife, to read as follows:

Sec. 17.11 Endangered and threatened wildlife.

* * * * *

(h) * * *

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Species Vertebrate population

----------------------------------------------- Historic range where endangered or Status When listed Critical Special rules

Common name Scientific name threatened habitat

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Arachnids

* * * * * * *

Spider, spruce-fir Microhexura montivaga. U.S.A. (NC, TN)...... NA................... E .............. NA NA

moss.

* * * * * * *

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Dated: November 23, 1993.

Richard N. Smith,

Acting Director, Fish and Wildlife Service.

[FR Doc. 94-1700 Filed 1-26-94; 8:45 am]

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