Systematic studies of some pseudoscorpions (Arachnida: Pseudoscorpionida) from the southeastern United States

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Virginia Polytechnic Institute


The pseudoscorpion fauna found in leaf mold of deciduous forests was used in this study and the collections were taken from the following localities: Plummer’s Isle, Montgomery Co., Maryland; Mt. Mitchell, Yancey Co., North Carolina; Greenville Co., South Carolina; several counties of East Tennessee and various state parks from Middle and West Tennessee; Breaks Interstate Park, Dickinson Co., Virginia; Blue Ridge Parkway, Floyd Co., Virginia; Mt. Lake, Giles Co., Virginia; and the Great Smoky Mountains National Park. Specimens were obtained from these collections by employing the Berlese apparatus. For mounting the specimens, the procedure utilized was a modification of the method used by Miss Louise M. Russell of the United States Department of Agriculture for mounting scale insects and aphids.

During the course of this investigation, more than two-thousand specimens were studied and the following species were identified: Verrucaditha spinosa, Mundochthonius sandersoni, Apochthonius moestus, Apochthonius barbarae, sp. n., Kleptochthonius (Kleptochthonius) crosbyi, Kleptochthonius (Kleptochthonius) multispinosus, Kewochthonius paludis, Chthonius (Ephippiochthonius) tetrachelatus, Microbisium confusum, Neobisium carolinense, Neobisium tenue, Neobisium holti sp. n., Microcreagris atlantica, Microcreagris rufula, Microcreagris lata, Pselaphochernes parvus, Illinichernes distinctus, and Dactylochelifer copiosus.

A redescription of 16 species and descriptions of two new species were presented. In these descriptions an account of a male from a genus previously thought to reproduce parthenogenetically was given. The discovery of a male of Microbisium confusum suggested that other males of the genus might exist. Emendations of species descriptions were based on a series of specimens, and the measurements taken of the various structures showed a greater range in length-width ratios and dimensions than was indicated in similarly published data for many of the species.

Type locality and place of deposit of the type specimen, collection data, previous distribution and new distribution records, and a discussion of the taxonomic status were presented for each species. A synonymy, beginning with the revision of the order by Chamberlin in 1929, was prepared for each taxon.

The possibility of using the male genitalia as tanonomic characters was considered and recomnendations were made. Males of two closely related species, Kleptochthonius crosbyi and Kleptochthonius multispinosus, were separated on the basis of dissimilar genitalic features.

Tergal and sternal chaetotaxy were found to vary considerably and strict application of these formulae was avoided. The chaetotaxal formulae of the coxae, carapace, and palpi were of systematic importance and their employment was urged.

Suggestions were made concerning the discarding of such terms as "maxilllae" and "apicalis maxillaris" from species descriptions and the adoption of the terms "palpal coxa" and "apical lobe of the palpal coxa," respectively.

The need for revisionary work, the use of measurements, and the value of systematic characters were discussed. The ecology, distribution, and means of dispersal of pseudoscorpions were also mentioned.

Ninety-eight illustrations were presented to accompany species description.