| IMPORTANT
WARNING!
With this issue
the current list of subscribers (started more than six years
ago) will be discarded and a new one will be started. To
receive future issues you must send me an email titled Onychophora
Newsletter followed by your name to rbt@biologia.ucr.ac.cr
(for example title message "Onychophora Newsletter Smith").
In the message text write your air mail address if you want
to receive the printed newsletter, or "Just email newsletter
to me" if you want to receive it in your current email. I
will email you back when your message is received. In the
unlikely case that you do not have an email, you can also
send that information by traditional mail to J. Monge-Nájera,
Biología Tropical, Universidad de Costa Rica, 2060
San José, Costa Rica and I will send you a confirmation
postcard.
Please remember
that I mostly self-finance both the newsletter and the web
page (by the way, thanks again to the three colleagues who
kindly have donated a total of $65 to help publication in
the last five years). Thus, I cannot afford sending the newsletter
to old addresses that may no longer be valid or may correspond
to people who lost interest in the group. IN SUMMARY: IF I
DO NOT HEAR FROM YOU, YOU WILL NOT RECEIVE FUTURE NEWSLETTERS,
I MUST DO THIS TO AVOID WASTING RESOURCES.
"It was a cold
night for a tropical country, but we did not think much about
it while crawling with our heads close to the ground and a
flashlight adapted to project a reddish light on a hill side
of Coronado, central Costa Rica. The place is so rainy that
it is called "Las Nubes" (The Clouds) and appears as a white
blotch marked "aerial photography prevented by clouds" in
many maps. About 300 years ago it was covered by a cloud forest
reduced today to tree belts along small creeks that intersect
lush-green pastureland. My friend Bernal and I were looking
for one of the most extraordinary animals in the world. So
extraordinary in fact, that even if we had been looking for
it 515 million years before present, we could still keep the
same "search image" in our minds. Of course you can say this
of very few organisms. The earliest fishes did not have jaws
and were heavily armored. Early amphibians and reptiles looked
like today's pulmonate fishes, the first birds were only a
type of dinosaur and the earliest mammals laid eggs. But the
animal we were trying to find looked the same as it does today
and even had the same size when metazoans (animals composed
of several cells) were just beginning to explore life…".
Source: Monge-Nájera,
J. The walking fossils. Fauna (USA), March 2001 issue.
Visit www.faunamagazine.com/
Cover illustration
The largest known
onychophoran, a 22 cm Epiperipatus from Costa Rica
and its newborn. The newborn is larger than the adults of
most species. This new species is being described by J. Monge-Nájera
and will be dedicated to its discoverer, Costa Rican herpetologist
Alejandro Solórzano.
Photo courtesy
of K. Nishida, University of Costa Rica.
This printed edition only
summarizes the contents of the electronic edition. To read
the full text please visit Onychophora Online in Tropiweb
(www.ots.ac.cr).
In a review of
nearly two centuries of studies about the phylum Onychophora,
which has existed without great modification in general body
organization for more than 500 million years, J. Monge-Nájera
analysed historical patterns in the scientific study of the
group. Most species were described around 1900 and in 1985-1996,
the other periods were low in taxonomical work but good for
studies of morphology and physiology. Worldwide, the number
of publications peaked around 1900 and then again in 1980
albeit it seems to be recovering in the late nineties. A total
of 131 species had been formally described when the text was
included in the recently published Arthropods of Mexico
(see below) and recent work increased it to nearly 140
species.
Two new families
in the Onychophora
G. Poinar
(USA) has described Tertiapatus dominicanus n.g.,
n.sp. (Tertiapatidae n.fam.) and Succinipatopsis balticus
n.gen., n.sp. (Succinipatopsidae n.fam.) (Lobopodia: Onychophora),
the first Tertiary fossils of the Lobopodia, from Dominican
and Baltic amber; respectively. Fossil onychophorans are rare
and these are the only known from amber. They show important
differences from modern species, particularly in their legs.
If accepted by the scientific community, the proposed two
new families will double the current number of onychophoran
families.
The Cambrian
"explosion": where is the bomb?
Julián
Monge-Nájera (Costa Rica) and Hou Xianguang (China)
(Revista de Biologia Tropical / International Journal of Tropical
Biology and Conservation 48 (2/3): 333-351, 2000) found that
a mature ecological community structure was generalized throughout
the world's tropics during the Cambrian (even biodiversity
and equitability indices were surprisingly close to modern
values) and that the morphological diversity and geographic
distribution of onychophorans indicate a significant pre-Cambrian
evolutionary history which does not support the "explosion"
hypothesis. They add that disparity within the phylum
was greater than it is today and its reduction may have been
associated with migration into the sediment when large predators
evolved.
Onychophorans
and the evolution of arthropods
Jan Zrzavy and
colleagues in the Czech Republic (Cladistics14 (3) 249-285)
did a cladistic analysis of traditional (i.e. morphological,
developmental, ultrastructural) and molecular (18S rDNA) data
sets (276+501 informative characters) to study the relationships
of all metazoan higher taxa and grouped the Onychophora with
Tardigrada and Arthropoda. Although based on the infamous
18 S rDNA analysis, the study deserves some confidence because
it takes into account morphological evidence and because it
does not deviate from the traditional cladogram for this three
groups, in which the Tardigrada are the weakest member (few
characters support its presence here).
Andrés
de-Haro in Barcelona, Spain (Boletin de la Real Sociedad Espanola
de Historia Natural Seccion Biologica. 94 (1-2) 103-113) finished
his comparative study of the cephalic region of Arthropoda,
Onychophora, Annelida and Lophophorata. A common origin is
proposed for them in a Coelomate trimeric organism. He added
"that Onychophora is an adelphotaxon of Arthropoda".
Invertebrate
Phylogeny for computers
D. Dudley Williams
of the University of Toronto (caddis@scar.utoronto.ca
www.citd.scar.utoronto.ca/CITDPress/)
has published the CD Invertebrate Phylogeny, a very
innovative multimedia tool to teach invertebrate zoology.
The Onychophora section is very good, updated to the year
2000 and illustrated with many color photographs. To study
invertebrate evolution, the student navigates in a phylogenetic
tree. Interactivity, the color illustrations and the automatically
self-grading tests are an important advance over traditional
textbooks.
Reproductive
anatomy of Brazilian onychophorans
Muriel Walker
and Sylvia Campiglia (Journal of Morphology. 237 (2) 127-136)
studied the seminal receptacula of Brazilian Peripatus
acacioi and found that it has a good oxygen supply. The
ultrastructure of the epithelium lining the seminal receptaculum
indicates that these cells secrete the material that forms
the luminal matrix that surrounds and provides nutrition for
the stored spermatozoa.
Indian onychophorans
rediscovered
The Indian Peripatus,
Typhloperipatus weldoni, has seldom been seen or collected
and is also as misterious as the tropical African onychophorans.
However, Indian zoologist A. Raghuvarman and colleagues recently
rediscovered it and reported that males shed their sperm on
the dorsal and ventral surface of the females (Journal of
Endocrinology and Reproduction 1 (2) 80-85), just as occurs
in some South African species. Then the spermatozoa may digest
and dissolve the thin cuticle of the micropores by hyaluronidase
that is probably present in the sperm heads and reaches the
ovaries for fertilization.
Sympatric
cryptic species in New Zealand onychophora
Steven A. Trewick
(Biological Journal of the Linnean Society 63 (3) 307-329
used allozyme electrophoresis to study live-bearing Peripatopsid
Onychophora from the North Island of New Zealand. Peripatoides
suteri had little intraspecific genetic variation but
within P. novaezealandiae five genetically differentiated
species were identified although none showed any consistent
morphological differentiatio. New Zealand authors normally
enphasize the active geophysical history of the region and
Trewick is no exception, discussing how this complex may result
from interaction of geologic history and low vagility in onychophorans.
Onychophora
of South Africa revisited
M. L. Hamer and
colleagues (Annals of the Natal Museum 38 (0) 283-312) reviewed
the nine described species of South Africa, two in Opisthopatus
Purcell, 1899 and seven in Peripatopsis Pocock, 1894.
These species are redescribed, illustrated and keyed to facilitate
future ecological and biodiversity studies. The authors suggest
that at least another five undescribed species exist. In the
past, South Africa was a leader in the study of onychophorans,
but production greatly decreased after the Second World War.
The country has, however, a powerful scientific establishment
and this revision should allow a revival of onychophoran studies
in the land of Mandela.
Intensive
research on Australian onychophorans
The last years
have been marked by a steady flow of papers about Australian
onychophorans: Australia has replaced Costa Rica as the most
productive country for this group. Here is a summary of work
on down-under species.
P. Sunnucks and
several Australian colleagues (Journal of Zoology 250: 447-460)
have reviewed the reproductive biology of the ovoviviparous
peripatus Euperipatoides rowelli which was found to
comply with the general trends published six years ago for
the phylum in general (Monge-Nájera, J. 1994. Reproductive
trends, habitat type and body characteristics in velvet worms
(Onychophora). Rev. Biol. Trop. 42 (3): 611-622). A female
can harbour one developed and one undeveloped batch of embryos
in each uterus. Excesses of developed embryos in one uterus
are counterbalanced by deficits of undeveloped ones, indicating
that females can use their paired reproductive tracts independently.
Gestation may require six months or more and sperm is stored
in good conditions for at least 9.5 months.
N. Curach &
P Sunnucks (Molecular Ecology 8: 1375-1386) believe that cryptic
species are common and studied the high local endemism of
Australian onychophoran, Euperipatoides rowelli. They
found that more than 70% of females had broods with multiple
paternity and suggested that this may increase the genetic
diversity of offspring, possibly to compensate for the low
genetic diversity at the population level.
P. Sunnucks and
A. C. C. Wilson (Molecular Ecology 8: 899-900) discovered
that genetic work with onychophorans can be very difficult.
Despite extensive optimization of many primer pairs, only
five useable loci were obtained in Euperipatoides rowelli.
Under standard conditions, only loci P6 and P23 gave scoreable
polymorphic patterns of the expected size. Nevertheless, they
concluded that E. rowelli is a species complex because
adjacent populations can differ by 20% or more in mtDNA COI
sequence.
K. Bittner and
colleagues (Acta-Zoologica 79 (4) 267-275 have studied the
ultrastructure of Austroperipatus aequabilis and
found that, like Neotropical onychophorans, it has the
"upside down" cell that has regularly been found in all
sensilla bearing a sensory peg (apart from the sensilla they
also occur within the labial epidermis. Since most sensilla
contain several different receptor cells, these authors consider
them to be complex sense organs, but the physiological-ethological
work that would complement this type of observations is still
scanty and much needed.
C. Brockmann
and colleagues (Entomologica Scandinavica Supplement. 1997;
is. 51: 319-329) studied the morphology of Ooperipatellus
decoratus (Baehr, 1977) and found that the genital tract
of adult females lacks the receptacula seminis found in juvenile
females. Albeit they lacked exact egg-laying dates, their
observations provide some support for a 19th century
report that eggs might require as much as about one year to
hatch.
The Onychophora
of Mexico
In Arthropods
of Mexico , published in the year 2000 by the Universidad
Nacional Autónoma de México, the very poorly
studied onychophoran fauna of that large neotropical country
was treated by J. Monge-Nájera. Only three species
have been described from Mexico: Oroperipatus eisenii
(Wheeler, 1898), Oroperipatus goudoti (Bouvier, 1899)
and Macroperipatus perrieri (Bouvier, 1899), while
at least 14 species are expected to exist. The area around
Mazatlán should receive special attention in future
surveys to better establish the northern limit of the phylum
in the American continent. Onychophorans probably arrived
in Mexico from South America in the last five million years.
The chapter also analyses the economic potential of onychophorans
in ecotourism, as specimens for zoology courses and in microsurgery.
Onychophora
Bibliography approaches the 1000 references
A frequent problems
with onychophoran papers, particularly acute in North America,
is their poor review of the literature. Pertinent papers are
not cited, and worse, the information they contain is clearly
unknown by authors in detriment of their own work. Since 1999
I have tried to solve this problem by including abstracts
and a bibliography in my web site Onychophora Online
(See "Organisms" in Tropiweb, www.ots.ac.cr).
The bibliography was kindly prepared by M. T. Ghiselin. Now
an updated Onychophoira Bibliography compiled by Michael T.
Ghiselin (California Academy of Sciences) and Michael L. Grieneisen
(manduca@sciref.org, Scientific Reference Resources) is available
and has 957 references, from "Aguinaldo, A.M.A.; Turbeville,
J.M.; Linford, L.S.; Rivera, M.C.; Garey, J.R.; Raff, R.A.;
Lake, J.A. (1997) Evidence for a clade of nematodes, arthropods
and other moulting animals. Nature 387(6632):
489-493" to "Zrzavy, J.; Stys, P. (1995) Evolution of metamerism
in Arthropoda: Developmental and morphological perspectives.
Quarterly Review of Biology 70(3): 279-295.
You can use (even search) that bibliography free of charge,
not only to avoid missing important papers while doing your
own research, but to
Onychophora
Mailing List and new CIM web page
Michael L. Grieneisen
has established an Onychophora mailing list for exchange of
ideas, questions, answers and news. If you wish to participate,
please visit http://www.onelist.com/community/onychophora.
Additionally, the Centre International de Myriapodologie (Paris)
has established a web page that you should see at: www.mnhn.fr/assoc/myriapoda/INDEX.HTM
It includes a
section on Onychophora. The CIM also publishes a bulletin
with yearly bibliographies, an interesting "In memoriam" section,
news about workshops and congresses, a directory of members,
etc. The bulletin is "a must" for anybody interested in myriapods
in general. |
