Abstract
A new genus, Basibulbus, is established to contain some seldom-collected, hard-bodied, haplogyne spiders from Chile. Because of their small size and the heavily scutate abdomen of males, these animals resemble gamasomorphine goblin spiders (Oonopidae), but differ in having a heavily sclerotized sperm duct within the male palp and a normal sperm opening in the epigastric furrow. Their tarsal organs lack both the longitudinal ridge and the serial dimorphism in raised receptor number that are considered synapomorphic for oonopids, but are elevated (albeit only at their proximal end), and the genus is therefore assigned to the Orsolobidae. Three new species are described: B. malleco (the type species) and B. concepcion from central Chile (regions VIII and IX), and B. granizo from further north (Region V). Only one other hard-bodied orsolobid genus has been described (Duripelta Forster from New Zealand); Basibulbus does not seem to be closely related to that genus, and represents another in the long list of relictual, phylogenetically significant, Chilean spider taxa. One of the possible synapomorphies of dysderoids, an oblique unsclerotized strip on the base of the anterior lateral spinnerets (which has been lost in higher gamasomorphines) has apparently been lost independently within Basibulbus. That character is present in B. granizo but absent in at least B. malleco.
Highlights
The Chilean spider fauna has long been of special interest to arachnologists, as many of the taxa found there are strikingly different from those found in other Neotropical regions, and often have their closest relatives not elsewhere in South America but rather in other south temperate parts of the world, especially New Zealand and Australia
When the Planetary Bio¬ diversity Inventory (PBI) project on goblin spiders (Oonopidae) began in 2006, special atten¬ tion was paid to bringing together, from various collections, all the known oonopid specimens from Chile
There turned out to be extraordinarily few specimens available; oonopids abound in all other parts of the Neotropics, the Chilean dysderoid fauna is domi¬ nated instead by members of the putative sister group of oonopids, the family Orsolobidae
Summary
The Chilean spider fauna has long been of special interest to arachnologists, as many of the taxa found there are strikingly different from those found in other Neotropical regions, and often have their closest relatives not elsewhere in South America but rather in other south temperate parts of the world, especially New Zealand and Australia. For example, are usually either present or absent in a given dysderoid genus, but in Basibulbus, they occur only in the type species, B. malleco The male palps of B. malleco and B. concepcion are similar, those of the more northern species B. granizo have an embolus that is much more complex
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