2002. Proceedings of the Indiana Academy of Science 1 :77-94 THE SPIDERS OF ILLINOIS AND INDIANA, THEIR GEOGRAPHICAL AFFINITIES, AND AN ANNOTATED CHECKLIST Joseph A. Beatty: Department of Zoology, Southern Illinois University, Carbondale, Illinois 62901-6501 USA ABSTRACT. The geographical affinities of the 586 spider species currently known from Indiana and Illinois are listed. An annotated checklist of the species is presented. Keywords: Spiders, Illinois, Indiana, zoogeography Although many new species have been de- standard references are often retained, even scribed in recent years, and more are to be though recent changes may have been made. expected, the spider fauna of the United States Alternate names are shown in parentheses. is still rather incompletely known. The only (These names are not necessarily synonyms.) well-known region of the country is southern Families, genera and species are listed in al- New England where 611 species have been phabetical order. recorded by the most recent summary (Kaston Many spiders are known to have a wide dis- 1981). tribution in eastern North America, about 75% A few other areas have been sufficiently of the Illinois-Indiana fauna having been re- well-worked that statements about their faunas corded from New England (Kaston 1981). may be of significance, and here I report on More specific distributional data are available one of these—Illinois and Indiana. The known only from records published in scattered re- spider fauna of Illinois stands at present at 550 visionary and ecological papers. Although species, that of Indiana, which has been less Moulder (1992) briefly described distributions intensively studied, at 367. The total for the of some common species, there has been no two states is 586 species (Table 1). Published attempt to summarize the geographical rela- checklists for these states include, for Illinois, tionships of the entire fauna. Kaston (1955), Moulder (1966, 1992), and Distributions of the species have been de- Beatty & Nelson (1979); for Indiana the most termined, when possible, from the most recent recent summary (Parker 1969) cites and sum- revision. If no recent revision exists data are marizes previous publications. Probably over taken from Kaston (1972), Richman & Cutler 600 species will eventually be recorded from (1978), Roth (1988) or other sources. The Illinois and almost as many from Indiana. geographic relationships of these spiders are There are probably very few species of spi- discussed below and summarized in Table 2. ders known from either of these states that do In calculating percentages of the fauna in each not occur also in the other. Among the excep- geographic area, introduced species (17 spe- tions are cave-inhabiting species from Indi- cies, 2.9% of the total fauna) and those whose ana, the cave region of which is somewhat ranges are highly restricted, poorly known or isolated from that of Illinois. anomalous (35 species, 6.0%) are excluded. Comparison of this checklist with those The percentages are based on the distributions previously published will show many name of the remaining 534 species. changes and deletions. These result from re- The criteria for placement of a species in a cent taxonomic revisions and discovery of er- particular geographic region are inevitably rors and duplications in previous publications. somewhat subjective. A species here classified The names used here, in most cases, are those as "Eastern" in distribution, for example, or- of the most recent revisions. For the conve- dinarily occurs from southern New England to nience of the non-specialist, names used in southern Georgia or northern Florida, and 77 78 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE Table 1. —Illinois and Indiana spider families Table 2. —Summary of North American distri- with number of species known from each state. butions of Illinois and Indiana spiders. 111. Ind. Total Number Percent of of total Agelenidae 20 13 21 Area of occurrence species fauna Amaurobiidae 4 3 4 Antrodiaetidae 2 2 Eastern 197 36.8 Anyphaenidae 9 5 9 Northeastern 98 18.4 Araneidae 54 36 57 Northern 85 15.9 Atypidae 3 13 Southeastern 73 13.6 Clubionidae 15 8 16 Throughout United States 57 10.6 Corinnidae 11 7 11 Western 9 1.7 Ctenidae 1 1 1 Central 8 1.5 Ctenizidae 1 1 1? Southern 7 1.3 Dictynidae 15 15 20 Uncertain 35 6.0 Dysderidae 1 1 1 Introduced 17 2.9 Gnaphosidae 44 23 46 Hahniidae 5 3 5 Linyphiidae 81 53 94 ical publications, unless the specimens have Liocranidae 13 5 14 been examined by the most recent reviser, are Loxoscelidae 2 1 2 not necessarily correctly identified. In families Lycosidae 52 38 55 that not recently in Mimetidae 4 3 4 have been revised entirety Mysmenidae 2 2 (the Linyphiidae, especially) changes of Nesticidae 1 1 2 names and additions or deletions of species Oecobiidae 1 1 are to be expected. Brief notes on some spe- Oonopidae 1 1 cies are presented in the checklist. Oxyopidae 3 1 3 Thirty-five Illinois species listed here have Philodromidae 22 16 22 not appeared on any of the previous check- Pholcidae 2 2 2 lists, and five have been added to the Indiana Pisauridae 10 8 10 checklists. Thirty of these have already been Salticidae 67 45 68 recorded in taxonomic revisions (25 species) Scytodidae 1 1 1 or faunal lists (5 species). The others have Segestriidae 1 1 1 Tetragnathidae 18 16 20 been collected in southern Illinois during the Theridiidae 55 32 56 last several years. Theridiosomatidae 1 1 1 Thomisidae 24 23 26 GEOGRAPHY Uloboridae 3 2 3 The largest component of the fauna (36.8%) Zoridae 1 1 1 consists of spiders that are distributed throughout most or all of the eastern United States (and often range into Canada or Mex- west to the 100th meridian (middle Kansas) or ico). Many of these species reach their west- beyond. It may or may not range into penin- ern limit at or about the 100 th meridian of lon- sular Florida or northern New England. Some gitude (Fig. 1), but their distributional limits species might be classified in a different re- often do not coincide closely with each other. gion by another person, but probably there Some of the eastern species extend across the would be few such changes. It is not likely plains to the base of the Rocky Mountains; that such differences of opinion would signif- others are not known from the northeastern or icantly alter the percentages shown in Table 2. southeastern extremities of the region. Some A checklist of Illinois and Indiana species have outliers in the west, often in the moun- is presented with the geographic area of oc- tains of Utah or neighboring states (Fig. 2), or currence of each species indicated. This list is in Pacific Coast states (Fig. 3). in part a compilation. It has not been possible The non-coincidence of distributions is to examine specimens of every species in- probably attributable mostly to differences in cluded in the list. Specimens reported from species tolerances to various climatic condi- either state in regional faunal lists or ecolog- tions, especially temperature and humidity BEATTY—SPIDERS OF ILLINOIS AND INDIANA 79 Figure 3. —An example of an eastern distribu- tion, with additional populations in Pacific states. Figure 1. —An example of an eastern distribution The species shown is Argiope aurantia Lucas (Ar- pattern. This is Theridion glaucescens Becker aneidae). (Theridiidae). er hypotheses, such as introduction and dis- (desiccation rate may be more important than persal, seem less probable. itself). disjunct humidity The ranges of some The second largest group of species (18.4%) species may have several causes: survival in has a northeastern distribution, the southern refugia, recent introductions, failure to rec- limit of which varies but often lies about at separate different ognize populations as spe- the latitude of North Carolina, somewhat fur- cies, collecting in or, lack of intervening areas ther south than the southern tip of Illinois rarely, incorrect locality labels. presence The (Fig. 4). Northern species, reaching their disjunct eastern species in of populations of southern limit in northern or central Illinois, western mountains is frequent (Fig. 2), and compose 15.9% of the fauna, southeastern consistent with the hypothesis that they orig- species 13.6%. Southeastern species are often inally had a wider distribution, which became at or near their northwestern range limit in the restricted as a result of climatic changes. Oth- southern tip of Illinois (Fig. 5). This sort of distribution is well known for a number of other groups of organisms found, in Illinois, chiefly in the small area of Gulf Coastal Plain Figure 2. —An example of an eastern distribution pattern, with disjunct populations in western moun- Figure 4. —An example of a northeastern distri- tains. This is Mimetus notius Chamberlin (Mimeti- bution pattern. The species shown is Sphodros ni- dae). ger (Hentz) (Atypidae). 80 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE Figure 5.—An example of southeastern distri- bution pattern. The species shown is Dolichognatha pentagona (Hentz) (Tetragnathidae). Figure 6. —An example of a distribution pattern where the species is found throughout the United that extends into the southern part of the state States. The species shown is Neoscona arabesca (DeCosta 1964; Ross 1944; Smith 1961). (Walckenaer) (Araneidae). Ranges of these species may extend in a nar- row coastal strip to southern New England un- are not determinable. Four of these species, der the moderating influence of the Atlantic. Ummidia tuobita, Ceratinopsis Xanthippe, C. Species found throughout all or most of the yola and Pirata triens, are known only from United States (Fig. 6) make up 10.6% of the Illinois. They will probably prove to have fauna.