distribution and natural history of mexican species of brachypelma

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1999. The Journal of Arachnology 27:196–200
DISTRIBUTION AND NATURAL HISTORY OF MEXICAN
SPECIES OF BRACHYPELMA AND BRACHYPELMIDES
(THERAPHOSIDAE, THERAPHOSINAE) WITH
MORPHOLOGICAL EVIDENCE FOR THEIR SYNONYMY
A. Locht, M. Yáñez and I. Vázquez: Laboratorio de Acarologı́a ‘‘Anita Hoffmann,’’
Facultad de Ciencias, Universidad Nacional Autónoma de México, Coyoacan 04510,
D.F., México
ABSTRACT. This comparision of Brachypelmides and Brachypelma species is based on newly collected
spiders and more than 100 specimens from five museum collections. The results show that there are six
endemic species of Brachypelma in western Mexico (B. auratum, B. baumgarteni, B. boehmei, B. emilia,
B. pallidum, B. smithi), presenting a gap in their distribution only where Brachypelmides klaasi is found.
Brachypelma vagans is distributed along both coasts of Mexico and Brachypelmides ruhnaui is found in
the central part of Mexico. Notes on natural history, a morphological comparison of 27 characters of these
genera, and a discussion of the generic affinities are included.
RESUMEN. De junio de 1997 a Octubre de 1998 se hizo un estudio comparativo de Brachypelmides
y de las especies de Brachypelma. Se revisaron especı́menes de ambos géneros obtenidos en el campo
recientemente y más de 100 especı́menes de cinco diferentes colecciones para realizar este estudio. Los
resultados muestran que hay seis especies endémicas al Pacı́fico mexicano de Brachypelma (B. auratum,
B. baumgarteni, B. boehmei, B. emillia, B. pallidum, B. smithi), presentando una distribución continua a
lo largo de la costa del Pacı́fico, siendo interrumpida por la distribución de B. klaasi. Brachypelma vagans
se distribuye en ambas costas y Brachypelmides ruhnaui en el centro del paı́s. Se incluyen notas de historia
natural, una comparación morfológica de 27 caracterı́sticas de estos géneros y una discusión de las afinidades genéricas.
The subfamily Theraphosinae is a speciose
group from the New World, representing some
of the most beautiful species of the family
Theraphosidae (Pérez-Miles 1992; Schmidt
1993; Smith 1993; Pérez-Miles et al. 1996).
The genus Brachypelma can be found from
Mexico to Costa Rica (Valerrio 1980; Smith
1994). The species from the west coast of
Mexico are particularly docile and colorful.
These traits have led to their being collected
in large numbers for the pet trade. The destruction of the natural habitat and the high
mortality before sexual maturity (99%) (Baerg
1958) are two factors that affect the populations of these species, and combined with the
illegal trade that normally involves the capture
of preadult and adult tarantulas, can cause the
extinction of these tarantulas. To regulate this
trade and prevent their endangerment, all the
species of this genus have been listed in appendix II of CITES.
In 1856 White described the first Brachy-
pelma species, B. emilia, that is endemic to
the Pacific coast of Mexico. Since then, another five species have been described that are
endemic to this area (B. auratum, B. baumgarteni, B. boehmei, B. pallidum, B. smithi)
(Schmidt 1992; Smith 1993; Schmidt & Klaas
1994; F.O.P. Cambridge 1897). Brachypelma
vagans Ausserer 1875 inhabits the same area
but populations also exist along the Gulf of
Mexico down to Costa Rica. Brachypelma epicureanum (Chamberlin) 1925 is found only
in the Yucatan peninsula (Smith 1994).
Schmidt & Krause (1994) described a new
species of Theraphosinae from the west coast
of Mexico. Although this tarantula is very
similar to those of Brachypelma, they argued
that it should be placed in a new genus because it has a pad of plumose hairs on the
femur IV, the males present a sharp tapered
embolus, and the females have a bipartite and
wide spermatheca. The species was named
Brachypelmides klaasi. However, in the same
196
LOCHT ET AL.—NOTES ON BRACHYPELMA AND BRACHYPELMIDES
197
Figure 1.—Distribution of the species of Brachypelma and Brachypelmides in Mexico.
year Smith (1994), after examining the types,
concluded that B. klaasi belongs to the Brachypelma group, being only ‘‘its most extreme
form.’’ Pérez-Miles et al. (1996) made a systematic revision and a cladistic analysis of
Theraphosinae, but they did not include Brachypelmides in their analysis. Schmidt (1997)
described another new Brachypelmides species from the central region of Mexico, B.
ruhnaui, adding support to his idea that Brachypelmides is a valid genus.
Our research of the species of Brachypelma
and Brachypelmides brings more data to the
question of the distinctness of these genera. It
also adds information on the natural history
and distribution data for these tarantulas.
METHODS
The collections visited and used for the
study included the following: the American
Museum of National History, the California
Academy of Sciences, Field Museum, Instituto de Biologı́a, UNAM, in Mexico City
(IBUNAM), and Estación de Biologı́a, Chamela, in Jalisco. The five collections have together more than 100 specimens of both gen-
era. All collection data were recorded. No
types were studied.
Fifteen field trips were made to the west
coast of Mexico from June 1997 to October
1998, and two more to the east coast in this
same period. Ecological and geographical data
were taken, and the specimens were brought
to the lab in Mexico City Laboratorio de
Acarologı́a ‘‘Anita Hoffmann.’’ Live specimens were put in controlled environment
chambers where their reproductive behavior
was studied (Yáñez & Locht 1998). The morphological characteristics of preserved specimens were analyzed in more detail, and the
figures presented in this work were made from
them. The specific collecting data for specimens are not given, but a range map (Fig. 1)
is included because we wish to protect the
species from the illegal pet trade.
DISTRIBUTION
Brachypelma is a common genus in the Pacific and Gulf coasts of México; the distribution of species along the west coast is only
interrupted by that of Brachypelmides klaasi,
and in the central part by B. ruhaui (Fig. 1).
198
Figures 2–5.—Frontal view of the right bulbs of
four species of tarantulas. 2. Brachypelma vagans
right bulb; 3. Brachypelmides ruhnaui right bulb;
4. Brachypelmides klaasi right bulb; 5. Brachypelma smithi right bulb.
Brachypelma smithi has a disjunct distribution, and B. vagans has the largest distribution. The only distribution that we could not
verify was that for B. epicureanum, which is
endemic to the Yucatan peninsula (Smith
1994). Field and collection data corresponded
in all other species. The distributions given by
Smith (1994) did not correspond with ours in
all cases, but they are generally not contradictory. The other collecting data found in the
descriptions of the species coincide with the
areas shown in Fig. 1 (White 1856; Ausserer
1875, F.O.P. -Cambridge 1897; Schmidt 1992;
Schmidt 1993; Smith 1993; Schmidt & Klaas
1994; Schmidt 1997; Locht et al. 1998).
NATURAL HISTORY
The natural history of Brachypelma species
differs little if at all from the Brachypelmides
THE JOURNAL OF ARACHNOLOGY
species. The following data are field and laboratory observations of the two genera.
Burrow Construction.—All the species
studied live in burrows found in the soil,
sometimes near rocks or trees, sometimes in
open field, but not far from vegetation. They
have only one entrance, a little wider than the
tarantula’s body size. When the tarantula is
active this entrance is clean and some silk can
be found. When the tarantula is inactive for a
long period the entrance is covered by soil and
leaves that the tarantula gathers with silk. A
horizontal tunnel leading from the entrance is
normally three times larger than the tarantula.
This tunnel is followed by a chamber 2–3
times bigger than the tarantula, where it molts,
then a vertical tunnel shorter than the first one
that ends with a larger chamber, where the tarantula rests and eats its prey. The mature female’s burrow in the reproductive season has
more silk in the entrance than usual.
Phenology.—The tarantulas of these genera
are long-lived. The males can reach maturity
in 7–8 years, living only one year or less after
the last molt, while the females reach maturity
in 9–10 years, then live 10 more years. Compared to other genera of the same subfamily,
they grow slowly (Smith 1994). In all species
pre-adults and adults molt at the end of the
dry season (June–November), males begin to
wander in search of the females after they
molt, and the females lay an egg-sac before
they molt. The egg-sac hatches 3–4 weeks before the rainy season begins. Males of all west
coast species wander during daylight, particularly in the morning and in the evening,
while the species of the east coast and center
wander at night.
Color pattern.—Brachypelma klaasi coloration is very similar to that of the six species of Brachypelma that are endemic to the
west coast. Brachypelma boehmei is the more
similar, having, like B. klaasi, black tarsi, orange-yellow metatarsi, tibias and patellas,
black femora and coxae and orange-yellow
hairs on the opistosoma. It differs only in the
carapace, which is yellow-orange in B. boehmei and black in B. klaasi. Brachypelma
baumgarteni is also very similar, but it has a
more reddish patella. Brachypelmides ruhnaui
has the same coloration of B. vagans and B.
epicureanum, differing only in having a yellow carapace, rather than black as in the others. Although all the species have striking col-
LOCHT ET AL.—NOTES ON BRACHYPELMA AND BRACHYPELMIDES
199
Figures 6–9.—Dorsal view of the cleared spermathecae of four species of tarantulas. 6. Brachypelma
auratum; 7. Brachypelma emilia; 8. Brachypelma vagans; 9. Brachypelmides klaasi.
oration, they are in fact cryptic within their
native habitat, making it very difficult to see
the tarantulas, even when they are out of their
burrows in daylight.
DISCUSSION OF GENERIC AFFINITIES
The data on distribution and natural history
provide support for the hypothesis that these
species are closely related. In the cladistic
analysis of Pérez-Miles et al. (1996) 27 characters were used. The characters in Brachypelma are: palpal bulb with concave/convex
apical region; relative width of sclerites II 1
III (measured at 20% of its length, from the
apex) wide (equal to or more than 10% of the
length of the bulb); lack of the paraembolic
and digitiform apophysis; presence of smooth
peripheric and supernumerary keels; and a
large subtegulum. The male’s tibia lacks a lateral process in the retrolateral region, a retrolateral cluster of spines and a prolateral process. It has two tibial apophyses; metatarsus I
lacks a basal process and is not strongly
curved, its flexion provided by the outer side
of the tibial spurs. Spermatheca widely fused
and with unilobulated receptacles; femur III
and tibia IV not incrassate; femur IV without
a retrolateral scopula; urticating hairs type I
and III present, type IV are absent. Trochanteral and coxal stridulatory hairs absent; coxal
spinules are absent; numerous labial cusps
present; fovea without a spherical process.
We compared all 27 characters among the
10 species analyzed and found that Brachy-
pelmides has only one character that distinguishes it from Brachypelma. This character
is the presence of a spermatheca with two receptacles separated or only partly fused. However, in the genus Brachypelma some spermathecae are widely fused (B. smithi, B.
auratum), some semi-divided (B. emilia, B.
baumgarteni, B. boehmei) and some only partly fused (B. vagans) (Figs. 6–9).
The palpal bulb morphology, principally in
the embolus, is distinctive in all the species.
Brachypelmides klaasi and B. runhaui have
the embolus sharper and more tapered, but do
not differ in the characteristics above listed
from Brachypelma. The palpal bulb of B.
klaasi, being wider, is more similar to that of
Brachypelma species from the Pacific coast.
The bulb of B. ruhnaui bulb is more similar
to the thinner bulb of B. vagans (Figs. 2–5).
The diagnosis of Brachypelma (Pérez-Miles
et al. 1996) shows that this genus does not
have retrolateral scopulae on femur IV. We examined the two species of Brachypelmides,
and we found no scopulae on the retrolateral
face of the femur IV. We found plumose hairs
in both genera. The patch of plumose hairs
mentioned for B. klaasi as a new character
separating these genera is not mentioned in B.
ruhnaui (Schmidt & Krause 1994; Schmidt
1997); and we could not find it in this species,
so this would only be a characteristic that distinguishes B. klaasi. Another characteristic
that Brachypelmides klaasi shares with the
200
species of Brachypelma is that it is very popular in the pet trade, but Brachypelmides is
not listed in appendix II of CITES.
Although, the distribution and morphology
likely provide strong evidence that Brachypelmides and Brachypelma are one and the
same genus, a revision of all the species of
these genera, not just those from Mexico, using cladistic analysis will provide a strong basis for placing the two species of Brachypelmides in the genus Brachypelma.
ACKNOWLEDGMENTS
We thank Dr. Norman I. Platnick, American
Museum of Natural History; Dr. Charles E.
Griswold, California Academy of Sciences;
and Dr. Tila M. Pérez, Laboratorio de Acarologı́a, Instituto de Biologı́a, UNAM for giving us the facilities to study the collections of
tarantulas of which they are in charge. We are
grateful to Graham Floater for helping with
the English translation. We are specially
thankful to Dr. Anita Hoffmann for encouraging us to write this paper. Thanks to DGAPA, UNAM for the financial support grant IN217397.
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Manuscript received 1 May 1998, revised 30 March
1999.
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