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although not recently studied is nonetheless representedby a dozen nominal species (Goodnight andGoodnight, 1942).The present study, based on the examination ofan extensive collection of these relatively rare harvestmen,made available largely through the effortsof James Reddell and field associates, shows thatTexella is far richer and more complex than previouslyimagined. In terms of species richness, the 21species now recognized make Texella one of thelargest Nearctic phalangodid genera (second in sizeonly to Calicina Ubick and Briggs (1989) with 25species). The high degree of complexity is evidentin the pronounced interspecific variation of bothsomatic and genitalic characters as well as in the patternsof relationship which emerge upon theiranalysis.Although this study greatly increases our knowledgeof Texella, there are probably few to manyadditional species to be discovered. This is suggestedby the high isolation of the species (abouttwo thirds are known from single localities) and thehighly disjunct distribution of the species groups.Even along the Balcones Escarpment, by far themost heavily sampled region, many caves andpatches of epigean habitat have not been adequatelysearched. Also, several of the species descriptionsare not adequate, being based on only a few specimens(three species are represented by single specimens),and give little or no indication of intraspecificvariation. Additionally, several populations ofTexella are currently known from only female andjuvenile specimens and, thus, can not be identifiedwith certainty. Clearly, much basic work remains tobe done on this genus and it is hoped that this studyencourages biologists, both cavernicole and epigean,to gather the additional material necessary to fillexisting gaps and test the various hypotheses presentedhere.Another aim of this study is to urge the conservationof Texella. There seems little doubt that thebiological complexity of Texella is a consequence ofa high degree of species isolation which is now evidentin the widespread pattern of localized endemism.Unfortunately, localized endemicity alsomay have negative ramifications, namely the increasedpotential for extinction. This is especiallyof concern in regions of rapid urbanization, as alongthe Balcones Escarpment, where development is apotential threat to the many biologically rich caves.At present, only two species of Texella (reddelli andreyesi) are afforded federal protection. However, ifrestricted distribution is an important prerequisitefor listing species, then comparable protectionshould be afforded all of the remalmng specieswhich, with the exception of T. bijurcata, have evenmore restricted ranges.MATERIALS AND METHODSThis study is based on the examination of about300 specimens of Texella, which (along with relatedPhalangodidae) were borrowed from the followingpersons and institutions:AMNH: American Museum of Natural History,Dr. Norman I. PlatnickCAS (including TSB collection): CaliforniaAcademy of Sciences, Dr. Wojciech J. PulawskiCDU: Mr. Darrell Ubick collectionMLG: Dr. Marie L. Goodnight collectionNMNH: National Museum of Natural History,Dr. Jonathan CoddingtonTMM: Texas Memorial Museum, Mr. James R.Reddell (including the collection formerly at TexasTech University and made available by Mr. JamesC. Cokendolpher)WAS: Dr. William A. Shear collectionSpecimens were prepared for study as were thoseof Calicina (Ubick and Briggs, 1989). Measurementswere made with ocular reticles in Olympusand Leitz dissecting microscopes, at 80 X, and arebelieved accurate to about ±0.03 (and from ±0.08to ±0.12 for leg II, depending on length). Detailedobservations and drawings were made with the helpof a compound, phase-contrast (Zeiss) microscopeequipped with a grid.Scanning electron micrographs were taken with aHitachi S-520 Scanning Electron Microscope. Specimenpreparation consisted of dehydration (soakingspecimens in serial baths from 75% to 100% ethanol),critical point drying (using liquid carbon dioxide),and mounting onto a stub. Specimens werecleaned manually, using eye lash brushes, both beforedehydration and upon being mounted. It waseventually discovered that the most effective methodof mounting specimens was to glue the fourth legs toa fine wire attached to the stub. This leaves thebody unspoiled by the adhesive and permitsmovement of the specimen into virtually anyposition. It should be noted that due to photoreductionof the micrographs, the original magnificationsgiven are useful only for facilitating comparison ofthe images; the actual dimensions can be determinedusing the accompanying scale bars. All measurementsare in millimeters, unless indicated otherwise.Tenninology.-Tubercles. This commonly usedterm refers to a wide variety of cuticular outgrowthsin harvestmen. To avoid unnecessary redundancy, it157