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In October 2019 I travelled to
Mexico in the context of the current project on Ninetinae. The main aim was
to collect the two genera of Ninetinae known to occur in Mexico, i.e. Pholcophora and Tolteca. The latter is a Mexican
endemic genus, and I had never seen a Tolteca alive even though I had
described the genus myself two decades ago. With a body length of only ~1 mm
they are among the smallest Pholcidae, and it was far from certain that we
would find them.
It turned out that Tolteca is an abundant spider in much of the low
dry forests along the Mexican Pacific Coast, like the one in Oaxaca shown
here. They live in the leaf litter and under small pebbles on the ground,
usually in drier sections than Modisimus
and Anopsicus, two other genera
common in the area. The male on the right is from Colima.
Mexico is extremely diverse in landscapes and ecosystems, and from Willis Gertsch's work in the 1970ies and 80ies we know that it
is home to a rich and varied pholcid fauna, second to Brazil only as far as
species are concerned. We thus took the opportunity to collect fresh material
of numerous species for future molecular work, and to search for new species
and missing sexes (Gertsch described many species based on one sex only).
Pushing the extremes we travelled some 6500 km through the states of
Guerrero, Michoacan, Colima, Jalisco, Nayarit,
Sinaloa, Durango, Coahuila, Nuevo León, Tamaulipas, San Luis Potosí, Hidalgo,
Puebla, Oaxaca, and Veracruz; in 28 days of non-stop collecting I got some
1380 adult specimens representing ~95 species, more than I had ever collected
at a single expedition before.
Even though our emphasis was on localities that had been visited by
arachnologists before, the percentage of new species was still remarkably
high. A first tentative estimate suggests that ~59 species are new, i.e.
~60%. This is lower than the global average published recently (~75%; Huber & Chao 2019), but it still
means that Mexico's current 171 species might represent no more than about a
third of the actual diversity.
The left image shows my companions
(Alejandro Váldez Mondragón and Luis Alejandro
Cabrera Espinosa) using one of the most effective methods to get Tolteca and
other tiny pholcids from the leaf litter. I am extremely thankful to the two Alejandros for their support, especially AVM for his help
with planning and with permits, for driving us safely for endless hours, for
being an enthusiastic and effective collector, and for sharing the beauties
of his country. This trip was financially supported by the German Research Foundation (DFG) project HU980/12-1.
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