The Brachypelma of Mexico

by Rick West 

Presently, there are 111 genera and 883 species of theraphosidae described in the world (Platnick, 2005).Of these, Mexico has the second highest diversity of theraphosid genera and species, second only to Brazil, with a reported 13 genera and 66 species.This number does not include those theraphosid species that undoubtedly exist just over the border into Mexico from northern and southern countries.Additionally, there are many more genera and species waiting to be discovered and described in Mexico (per. ob. and per. comm. G. Odell, A. Locht)

At the moment, there are 20 described species of Brachypelma reportedly ranging from Mexico to Panama, including two from Caribbean island locations.The two Caribbean species are doubtful, as the exact collection location of the type specimens is inadequate.Of the 20 known Brachypelma species, 13 occur in Mexico … 12 of which are endemic to Mexico.

Of all the theraphosid spider genera found in Mexico, the Brachypelma stand above all others in their docile nature, large size and colorful beauty.Although I have spent more than 20 years studying most of the Mexican Brachypelma species, there is still a lot more that remains to be discovered about them in their natural habitat.The following is a brief overview from my field notes on the Mexican Brachypelma.

Climate:

Mexico has two seasons - a rainy summer season that extends from June/July to October/November and a dry winter season that runs from October/November to June/July.

Annual rainfall in the Pacific ‘frost free’ Mexican states, where Brachypelma is found, ranges from 16 – 63 inches.In the eastern Mexican states, where only Brachypelma vagans (Ausserer, 1875) occurs, rainfall is higher and ranges from 47 - 63 (or more) inches annually.Humidity is lower in the drier months and higher in the winter months as well as its lower at the higher elevations, 18 – 90+% depending on the season, vegetation and soil type, time of day, elevation, and present weather conditions (hot, cloudy, raining, etc.).

Regional temperatures aren’t that dramatically different between seasons in Mexico.Day temperatures average 75 – 85 F in the drier winter season and 80 – 90 F in the wetter summer season and night temperatures range from 50s – 70s F, depending upon elevation and the type of vegetation zone.

Distribution of Mexican Brachypelma:

With the exception of Brachypelma vagans (Ausserer, 1875) and B. epicureanum (Chamberlin, 1925), which are found in the Atlantic states, all of Mexico’s other Brachypelma species are found along the Pacific slopes of the Sierra Madres (Western and Southern), the western side of the Transverse Volcanic Belt, and the Valley of Mexico mountain ranges.

To date, no other Mexican Brachypelma species, other than B. vagans and B.epicureanum have been reported south of the Isthmus of Tehuantepec and no Brachypelma species has been reported living above 7000 feet or in Cloud forests.

Breeding Season:

The breeding season of most (if not all) of the Mexican theraphosidae occurs during the rainy summer season.Both sexes of all the Mexican Brachypelma species appear similar in color and/or pattern, however, there are some differences in morphology, color intensity, body sizes and longevity within all the species.Eggsacs are constructed through the drier winter months with young emerging and dispersing in the late spring, just before the onset of the early summer rains.

Breeding studies of Brachypelma species have found evidence that suggests adult and post-adult females do not mate and produce an eggsac every year

(per. comm. R. Rojo, M. Yanez).More studies need to be conducted in this area to prove or disprove this.If proven, this would make a stronger argument for why these highly sought after theraphosid species should be protected, other than on C.I.T.E.S., and why local captive breeders should be allowed to both market controlled numbers for commercial export as well as re-introduction a percentage of their offspring back into the maternal habitat, so as not to disrupt the natural gene pool, to ensure healthy wild populations.

Mexican Brachypelma:

The most northerly species of Brachypelma in Mexico is Brachypelma emilia (White, 1856) found west of the Sierra Madres Occidental mountain range in the states of Sinaloa, Durango and Nayarit.This highly colorful species is a fossorial burrower whose habitat ranges widely from the drier coastal thorn forests and savannahs, through the palm transition forests and wetter inland tropical deciduous forests, up into the higher and cooler elevations of the pine-oak forests.B. emilia is found under dense thorny thickets or leafy foliage in both forested and disturbed areas and seemed to prefer constructing their burrows under large trees or dense leafy ground cover as opposed to being exposed in open sunlight. The dense leafy ground cover appears to retain higher humidity around the burrow as well as provide a good microhabitat for a myriad of vertebrate and invertebrate prey.Most burrows ranged between 20 – 100 cm in length, depending on the size of the specimen occupying it, and were self-excavated in sandy/gravel soil that often followed the underside of a large Orejón or Elephant Ear tree [Enterolobium cyclocarpum] root or the underside of a partially buried large rock.Unlike so many other fossorial theraphosinae species, the burrow entrances had no telltale trace of silk to indicate a theraphosid or spider occupied it, so, there was never any indication of whether you’d find a land crab, toad, lizard, rodent or B. emilia until you get to the end of it.

B. emilia burrows, like most fossorial theraphosid taxa, have a secondary ‘refuse chamber’ that laterally branched off from the main burrow.While excavating burrows, it was common the come to the end and find it unoccupied … only to backtrack and find the specimen hiding in the refuse chamber amongst old eggsacs, exuvia and the chitinous remains of former prey items.

Directly to the south, but not sympatric (overlapping in range) with B. emilia, is Brachypelma klaasi (Schmidt & Krause, 1994) that has only been found in Jalisco state.The color of this species is entirely black with longer rusty red hairs on the abdomen and all tibia and metatarsi.Like B. emilia, this very robust species can also be found in all three Pacific vegetation zones (thorn, tropical deciduous and pine-oak forest).B. klaasi is a fossorial species whose modified or self-excavated burrow can be found under fallen logs, large rocks, inside old stumps and large tree roots, amongst thorny brush or tall grass thickets on sloped cattle pastures and from sea level to 6000’.Only lowland burrows were found to have silk around the burrow’s entrance.Most burrows appear to be modifications of pre-existing burrows, possibly made by some other small animal, or a natural cavity, that ranged from 20 – 60 cm in length.

I should mention that one large adult female B. klaasi was observed crossing the coastal highway on a mid-July day with a road surface heat of 110 F.On another mid-July day, a large adult female was found wandering (hunting?) 10 feet up in a thorny acacia tree.Researchers have also found B. klaasi wandering in acacia trees and one living in a natural cavity up in a tree.Local people have reported seeing B. klaasi eating small lizards and birds in the acacia trees (per. comm. M. Yanez).Such behavior is unexplainable for a fossorial species that shuns daylight, like most theraphosid spiders.

Sympatric with B. klaasi, to the east, is Brachypelma auratum Schmidt, 1992.B. auratum ranges from central eastern Jalisco south through north eastern Colima and into central western Michoacan state where it overlaps in range with Brachypelma smithi (F.O.P. – Cambridge, 1897).B. auratum is strikingly marked with an orangey red ‘flame’ on each patella (knees) that boldly stands out against the velvety black legs and body.B. auratum seemed to be more of a montane fossorial species, mainly found in the upper fringes of tropical deciduous forests and the cooler and drier elevations of pine-oak forests.Temperatures and humidity in the range of B. auratum are a little lower than those Brachypelma found closer and lower in the Pacific coastal states.

One B. auratum burrow was found communally occupied by a small frog Eleutherodactylus occidentalis (Taylor, 1941).More burrow examinations and studies need to be done in order to determine if there is any benefical or commensal relationship between these two co-habitants.

Sympatric with B. klaasi and B. auratum is Brachypelma smithi (F.O.P. – Cambridge, 1897) that ranges from southern coastal Jalisco to northwestern Oaxaca and inland to the State of Mexico and Morelos.B. smithi is the ‘flagship’ for beauty in the genus Brachypelma.Rather than described the color and pattern, see the attached images.This was the first Brachypelma to be placed on CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna) in 1985 out of concern for increased collecting for the commercial pet trade.In 1994, all Brachypelma were placed on Appendix II of CITES to control their commercial trade until more studies can determine if populations are sustainable enough to withstand commercial collecting before considering if one or more species should be taken off this list.Regardless of the CITES listing, it is illegal to collect and remove any theraphosid spider from Mexico without a scientific collecting permit.

B. smithi, like B. emilia, is fossorial and burrows are difficult to locate and often occur in dense thickets or vegeation of both dry thorn forests or tropical deciduous forests under large angular rocks or tree roots.There are no traces of silk at the burrow entrance and the interior can often be multi-tunneled, especially if populations occur on rocky talus slopes.Searching for burrows is problematic in that you sustain multiple lacerations from razor grasses, thorny vines and sharp branches.In addition, these areas make good retreats for venomous snakes as well as ‘face level’ paper wasps (aka - Spanish Dagger).

I have found that most Brachypelma species that exist along the Pacific coastal states, seem to prefer living more inland and away from near the ocean.I believe this is because of the fossorial competition and disruptive and nocturnal nature of a land crab,Gecarcinus quadratus de Saussure, 1895.This colorful land crab, about the same size as adult Brachypelma, range from Sinaloa to Colombia and, during the summer rainy season, can be found coming down out of the forests and crossing the roads by the thousands to spawn in the ocean.Some Brachypema populations can be found close to the ocean but only in areas not suitable for land crabs.

I have seen many color and dorsal pattern variations in B. smithi.I believe that some Brachypelma species, such as Brachypelma annitha and B. hamorii Tesmoingt, Cleton & Verdez, 1997, found in the same range and habitat as B. smithi, are merely color variants of B. smithi whose descriptions were based on artifical characters.To date, DNA profiling of the Brachypelma has proven to be an unreliable taxonomic tool but resent research in this area is showing promising results.More careful and professional taxonomic studies need to be done to resolve the question of variants versus what is a valid Brachypelma species.

In the middle of, and sympatric with, the B. smithi distribution is Brachypelma boehmei Schmidt and Klaas, 1994, that inhabits the thorn forests of southeastern Michoacan to northwestern Guerrero state.B. boehmei is the most gorgeous (if a spider can be called gorgeous) of the Brachypelma (see image).This is a fossorial species where early instars were found in silk free burrows under fallen logs or large angular rocks.Some ultimate females were found in burrows similar in appearance to lowland B. klaasi burrows, either on level or sloped ground amongst thorny brush thickets or under large rocks.

In one burrow, I found and photographed a 12” Balsas ground snake, Sonora michoacanensis Duges, 1884, peacefully co-habiting with a female B. boehmei.This behavior remains a mystery why an otherwise predatory large spider would allow such a co-habitation with a snake.To my knowledge, this is the first report of a snake being found unmolested in an occupied theraphosid burrow.

Also found in the overlapping range of B. boehmei and B. smithi is Brachypelma

baumgarteni Smith, 1993.Little is known about the natural history of this presumably fossorial Brachypelma species.The color of B. baumgateni is similar to B. smithi but the legs are golden brown with a red ‘flame’ on all patella.Some researchers suggest that B. baumgarteni may be a natural hybrid in nature, between the sympatric species B. boehmei and B. smithi (per. comm. M. Yanez), while others claim it is a valid species (per. comm. A. Smith).Although there have been claims that B. baumgarteni has been bred in captivity, a question of doubt still remains as to whether or not this is a valid Brachypelma species.It is interesting to note that mating B. boehmei with B. smithi will produce B. baumgarten ‘look-alikes’ but breeders report the offspring are sterile.Again, more professional studies need to be done in the field to determine whether this is a valid species or merely a natural hybrid in nature.

In the southern and inland range of B. smithi is the sympatric species Brachypelma verdezi Schmidt, 2003.Prior to its recent description, B. verdezi was regarded for many years in the pet trade as either a hobby-produced hybrid or was erroneously referred to as ‘Brachypelma pallidum’.The latter was an invalid species name.B. verdezi is a valid and distinct fossorial species that occurs only in Guerrero state and has two color variations; dark brown with a buff carapace and a dark cephalic ‘V’ or dark brown with a buff carapace, lacking the cephalic ’V’, and narrow pale paired longitudinal stripes on the appendages.

Little is know of the natural history of this species at this time but a few specimens of B. verdezi found by colleagues were living in silk free burrows under large rocks in sparse dry thorn forest predominated with columnar and prickly pear cacti, grasses and scattered fan palms.

Live B. verdezi and B. smithi, are commonly sold in one coastal town ‘Mercado’ (market) by herbateros for holistic medicinal purposes.At this time, I do not know what the medicinal purpose is that these species are used for.

To the north of B. verdezi, but not known to be sympatric with any other Brachypelma species at this time, is Brachypelma ruhnaui (Schmidt, 1997).This striking black species, with its black body and legs, sulfur yellow carapace and red abdominal guard hairs, is only known from Mexico, D. F. and Morelos state.Possibly B. ruhnaui extends into the northern Guerrero and northeastern Puebla states.I have found specimens only a few miles from these state borders and habitat doesn’t change that significantly.B. ruhnaui is a fossorial species that lives in dry thorn forest habitat.Burrows ranged from 30 – 80 cm in length.The interiors of some burrows were very convoluted and had multiple chambers.Some of the older more occupied burrows had small traces of silk around the entrance but most had no trace of silk.Burrows were found along cattle fence lines amongst tall grasses, under large tree roots, or, were under large angular rocks either in thorny thickets of bush or under large exposed rocks in the sloped and exposed corn fields.

From my personal investigation, it should be stated here that I do not believe that B. ruhnaui is a Brachypelma species.I believe that with a proper taxonomic investigation and careful re-examination of the morphological characters, this will be found to be an Aphonopelma species.

The most southerly Brachypelma species found in the Pacific coastal states of Mexico, at this time, is Brachypelma schroederi Rudloff, 2003, and only known from Oaxaca state.This fossorial species makes its burrow in more open and patchy dry thorn forest habitat under large rocks, partially embedded in the ground, or in burrows possibly made by other animals such as lizards or rodents.Traces of silk can be found around the burrow entrance of larger specimens.B. schroederi is one of the smallest of the Mexican Brachypelma and the only one that is monochromatic black.Like B. verdezi, very little is known about the natural history of this species at this time, as it’s a relatively new find.

In the southern Atlantic states of Mexico, there are two Brachypelma species. The first, Brachypelma vagans (Ausserer, 1875) is a fossorial species that ranges from the Mexican states of southern Veracruz and eastern Puebla to Quintana Roo and inhabits both tropical deciduous forests and tropical evergreen forests.On the northern tip of Yucatan, some populations of B. vagans can be found in the transition of tropical deciduous forest and the dry thorn forest.B. vagans has two color variations; entirely velvet black with long orangey red hairs on the abdomen and the second variation is like the aforementioned but has a wide buff-colored fringe around the carapace.The latter color is also common in earlier instars of both variants.B. vagans appears to be a species that does well in areas disturbed by humans as large populations with close spatial distributions can be found in cattle pastures, lawns or plantations.Dr. S. Reichling and Dr. C. Schillington have studied the ecology of B. vagans.One interesting aspect about this species is the ‘columnar dispersal’ of early instars.When the young eventually disperse from the maternal burrow, they have been observed setting off in either long single or multi columns.The only plausible explanation given for this behavioral phenomenon is that the young will eventually settle to form ‘aggregations’ in their populations.

In addition, Instituto de Biotecnologia in Cuernavaca, Morelos, Dr. Alagon’s lab is investigating Mexican theraphosid venoms for possible pharmaceutical and agricultural applications, in particular that of B. vagans (per. comm. A. Alagon and G. Odell).

In the State of Campeche, the shaman or herbateros of the Chol Indians, direct

descendants of the Mayans, use B. vagans as medicine to cure fellow village members afflicted with ‘Aire de tarantula’ (tarantula air).The ailment is usually diagnosed as anything from a bad cough, chest pain to a burning stomachache.Once diagnosed as tarantula air, the shaman grinds up a live B. vagans in a cup then mixes this slurry with 97% alcohol.The concoction is poured several times through cotton, undoubtedly to filter out any urticating hairs, and is then given to the patient to drink.Sometimes, more than one of these strong alcoholic drinks is needed – yah, right!(per. comm. R. Rojo).

The second Mexican Brachypelma found in the Atlantic states, is Brachypelma epicureanum (Chamberlin, 1925).This is a fossorial species that only inhabits both the dry thorn and tropical deciduous forests of the Yucatan Peninsula.Specimens have been reported found under large slabs of limestone rock.Very little is known about the natural history of this species.Some researchers claim it is an Aphonopelma species while others contend it is merely a geographical variation of B. vagans.The color of this species is very similar to B. vagans - entirely dark brown with a lighter colored carapace and long red hairs on the abdomen.The primary difference between this species and B. vagans is the shape of the genitalia.Only further investigation and taxonomic studies will determine what genus this should be assigned to and if it is a valid species.

In conclusion, I have little doubt that one or more Brachypelma species still wait to be discovered and described from Mexico.Very little taxonomic study has been done on the Mexican theraphosid spiders but lately there appears to be growing interest in this area amongst Mexican students and researchers thanks to a new website - www.geocities.com/tocatlampa/index.htm [in Spanish].

In conclusion, I will leave you with this charming Mexican Nahua Indian meaning for tarantulas, which they consider ancient spiders.Nahuas call all tarantulas tlalueuetl, tlal comes from the Nahua word tlalle that means the owner of a big piece of land and ueuetl means old or ancient.So, to the Nahua Indians, the word tlalueuetl means, “the ancient owner of a big piece of land” … which is so true when you think of tarantulas (theraphosidae) existing on this planet for over 23 millions years.(per. comm. M. Leal).

For more images of Brachypelma species, see the Photo Archive at:

www.birdspiders.com

References:

Locht, A., M. Yanez & I. Vasquez.1999.Distribution and natural history of

Mexican species of Brachypelma and Brachypelmides (Theraphosidae,

Theraphosinae) with morphological evidence to support their synonymy.J.

Arachnol. 27(1): 197-200.

Platnick, N.I.2005.The world spider catalog, version 5.5.American Museum of

Natural History, New York.

Reichling, S.B.2000.Group dispersal in juvenile Brachypelma vagans

(Araneae, Theraphosidae).J. Arachnol. 28(2): 248-250.

Rudloff, J.-P. Eine neue Brachypelma-Art aus Mexiko, Brachypelma schroederi

sp. n. (Araneae: Mygalomorphae: Theraphosidae: Theraphosinae). Arthropoda

11(3): 2-15

Schmidt, G. E. W. (2003g). Das männchen von Brachypelma verdezi sp. n.

(Araneae: Theraphosidae: Theraphosinae), einer häufig mit Aphonopelma

pallidum verwechselten vogelspinnenart aus Mexico. Tarantulas of the World

86: 4-9 (also 87: 4-9).

Smith, A.M.1994.Theraphosid spiders of the new world. Vol. 2. Tarantulas of

the USA and Mexico.Fitzgerald Publ., London.196 pp.

Yanez, M. 1999. Taxonomía y biología de Brachypelma klaasi (Schmidt et

Krause, 1994) (Araneae: Theraphosidae).Masters thesis, Faculty of Science,

UNAM, Mexico.87 pp.

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