1992. The Journal of Arachnology 20:88-93

HABITAT SEGREGATION BY SPECIES OF METAPHIDIPPUS (ARANEAE: SALTICIDAE) IN MINNESOT A

Bruce Cutler: Electron Microscope Laboratory and Department of Entomology , University of Kansas, Lawrence, Kansas 66045-2106 US A Daniel T. Jennings: North Central Forest Experiment Station, 1992 Folwell Avenue , St. Paul, Minnesota 55108 USA

ABSTRACT. Four species of Metaphidippus (Araneae: Salticidae) occupied different habitat types in Min- nesota; M. arizonensis was found exclusively in sand prairie; M. flavipedes was almost completely restricted t o conifers; M. insignis primarily inhabited open, non-canopy vegetation (e .g., grasslands); whereas, M. protervus occupied most habitats, but most evidently shaded forest understory and wetlands . Reasons for such habita t partitioning are conjectural . Size differences among the four species probably were not ecologically significan t based on Dyar's constant; however, competition for prey may have influenced habitat selection .

Metaphidippus is one of the largest genera of To avoid sampling bias, individual sites wer e jumping in (Richman & counted only once even if repeatedly collected. Cutler 1978) . Revision of the by other A site was considered a stand of vegetation iso- workers will probably redefine the an d lated from another stand by an intervening stand introduce new generic names ; however, the spe - of different vegetation, or by a large physical ob - cies discussed here will remain in one genus. stacle. In many cases, collected sites were sepa- When we first started collecting jumping spi- rated by many kilometers ; others were adjacen t ders in Minnesota, it quickly became evident tha t and differed only in vegetation . All sites were i n different species were found only in specific hab- Minnesota. Collecting dates were from April- itats. This was particularly noticeable in specie s October. ofMet aphidippus because our favorite collecting Negative catches were not recorded ; tabulated methods—sweep netting and beating vegeta- data consisted only of samples that yielded spec- tion—garnered large numbers of these vegeta- imens. Carapace widths between row III eyes tion-inhabiting spiders. Over a 25 year period , were measured with an ocular micrometer for 5 0 most parts of the state were visited and habita t mature females ofM. flavipedes, M. insignis, and data recorded whenever salticids were collected . M. protervus, and for 35 mature females of M. The data was analyzed and a hypothesis for hab- arizonensis. Tukey's Studentized Range (HSD) itat segregation (Dyar's constant) considered . Test (SAS 1985) was used for comparisons o f carapace widths among species at P 0.05. METHODS RESULT S Specimens of Metaphidippus arizonensi s (Peckham & Peckham), M. flavipedes (Peckham Figure 1 shows the Minnesota counties col- & Peckham), M. insignis (Banks), and M. pro- lected and the species of Metaphidippus found. tervus (Walckenaer) were collected predomi- Table 1 compares species presence/absence with- nantly by sweep netting; however, beating foliage in the different habitats . With only one excep- also yielded a few specimens . Collection height s tion, because of small sampling size (deciduous- were not controlled or recorded. If necessary, tree foliage), species were unequally distributed laboratory rearing was done in the case of an- within each habitat investigated (Table 1) . We tepenultimate and penultimate instars to confir m conclude that 1) specific habitats support few (1— identifications based on adult genitalia. Spiders 3) species of Metaphidippus, and 2) species pres- were kept at ambient temperatures in Petri dish - ence within a habitat usually is dominated by a es with moist pieces of sponge, and fed Dro- single species, less frequently by two species . sophila adults and Tribolium larvae until mature . Habitat breadth or specificity (i .e., the numbe r 88

CUTLER & JENNINGS—HABITAT SEGREGATION OF METAPHIDIPPUS 89

Table 1 .-A comparison of species occurrence within and over all habitats studied in Minnesota, 1964 to 1989 .

Sum of individual collections/habitat by Metaphidippus species Habitat arizonensis flavipedes insignis protervus Conifer foliage 0 41 0 0 Deciduous-tree foliage 0 1 0 3 Coniferous-tree understory 0 2 0 7 Deciduous understory 0 0 0 3 1 Wetland 0 0 1 1 0 Old field 0 0 1 6 Mixed meadow 0 0 13 10 Mesic prairie 0 1 19 1 Sand prairie 7 0 1 2 Crops 0 0 1 4 All 7 45 36 74

of habitats occupied by each species) also varied common Misumenops species were most fre- considerably among the four species of Meta- quently found on different shrub species . Turner (Table 2). For example, M. arizonensis & Polis (1979) concluded that it was unlikely that was found only in sand prairie, whereas M. pro- widespread competition for food and space re- tervus was found in 9 of the 10 habitats inves- sources occurred among guild members . Inter- tigated. However, these results must be inter- ference competition, i.e., interspecific predation preted with caution because sampling intensity by guild members, was evoked as the determi- varied among habitats. nator of guild structure (Turner & Polis 1979) . Dice-Lena diagrams of carapace width mea- Within Metaphidippus, species determina- surements are given in Figure 2 for the four spe- tions can be difficult . Misidentifications are pos- cies ofMet aphidippus . Means for all species pairs sible, indeed probable . For example, it is likely were significantly different (P 0 .05), except the that M. exiguus (Banks) found on jackpine (Pinus pair M. insignis – M. protervus. banksiana Lamb.) in Manitoba (Bradley & Hink s 1968) are M. flavipedes (Peckham & Peckham). DISCUSSION Nevertheless, clearly there are indicated habita t Species partitioning by habitat is a well known preferences for Metaphidippus species in the lit- phenomenon among many groups of erature (Allen et al . 1970; Berry 1970; Dondale (Schoener 1974). Good examples exist for the et al. 1979; Ives 1967; Jennings & Collins 1987a, predominantly ground-dwelling lycosid spiders b; Legner & Oatman 1964 ; Lowrie 1968 ; Mason in the genus Pardosa (Den Hollander & Lof 1974 ; & Paul 1988 ; Stiettenroth & Homer 1987 ; Young Greenstone 1980 ; Hallander 1970; Lowrie 1973 ; & Lockley 1990). Vlijm & Kessler-Geschiere 1967; Vogel 1972). However, habitat partitioning among non-snare building, vegetation-inhabiting spiders has bee n Table 2.—Comparison ofMetaphidippus species oc- little investigated. A few papers discuss the hab- currence among 10 habitats in Minnesota, 1964 to 1989. itat preferences of individual species (Jennings 1976, and papers cited therein; Jennings & Col- No. of Sum of habitats collections lins 1987b), but rarely in the context of coexisting species yielding phylogenetically related species . Turner & Polis Species found in species (1979) considered the members of a raptorial , non-snare building guild of spiders on inflores- M. arizonensis 1 7 cences of a coastal sagebrush community in Cal- M. flavipedes 4 45 M. insignis 6 36 ifornia. Included were three species of the crab M. protervus 9 74 genus Misumenops . Each species over - All species 10 162 lapped in occurrence on the shrubs, but the two

90 THE JOURNAL OF ARACHNOLOG Y

Figure 1 .-Localities ofMetaphidippus species collected in Minnesota . M. arizonensis = *, M. flavipedes =- 0, M. insignis = 0, M. protervus = A .

During our study, special efforts were made t o as reported by Bradley & Hinks (1968) . In Min- collect spiders on tamarack, Larix laricina (Du nesota, M. flavipedes was collected on all species Roi) K. Koch, because it is the only deciduou s of conifers sampled except for tamarack an d conifer in Minnesota. Despite these efforts no northern white-cedar (Thuja occidentalis L.); species of Metaphidippus was found, although however, the latter was scarcely sampled . Strat- another , Eris militaris (Hentz), ton et al . (1979) also sampled northern white - did occur. Interestingly, Ives (1968) reported both cedar in Minnesota and found several genera of E. militaris and M. protervus from tamarack in salticids, but species of Metaphidippus were iden- Manitoba; however, M. flavipedes is the expected tified only to genus. In his investigation of spiders conifer-inhabiting Metaphidippus in Manitoba, on a small island in northern Lake Michigan,

CUTLER & JENNINGS—HABITAT SEGREGATION OF METAPHIDIPPUS 9 1

= upper limit of range

1 .5 = +1S.D.

1 .45 mean

1 .4

1 .35 =-IS.D.

1 .3 = lower limit ofrange

1 .2 5

1 .2

1 .1 5

1 . 1

1 .05

1 .0

0 .9 5

0 .9

0 .85

0 .8

A F I P

Metaphidippus species

Figure 2 .-Dice-Lerra Diagram for distance between row III eyes in four Metaphidippus species . (A = Me- taphidippus arizonensis, F = M. flavipedes, I = M. insignis, P = M. protervus).

Drew (1967) carefully collected from different and on northern white-cedar, whereas M. pro- vegetation types including trees. M. flavipedes tervus was commonest in the herb-shrub stratu m was among the commonest species collected on of the upland hardwood forest . Both species of Juniperus communis (reported as J. depressus) Metaphidippus occurred at lower frequencies in

92 THE JOURNAL OF ARACHNOLOGY

the old field community and in other commu- ACKNOWLEDGMENTS nities (marshes, beach) . We thank those who have helped this study i n That small salticid species should partition b y various capacities . Robert Dana, Minnesota ; and type of space occupied, rather than successiv e Ronald L. Huber, Kansas assisted with field col - temporal occurrence, was predicted by Enders lections in Minnesota. Permission to collect o n (1975) based on previous habitat-sampling stud- properties under their supervision was gener- ies. The Metaphidippus species we investigated ously provided by The Nature Conservancy – had similar temporal occurrences of adults, i .e., Minnesota, and by Cedar Creek Natural Histor y many mature males and rare mature females in Area–University of Minnesota . Portions of thi s September and October. Both sexes of all four research were completed during the junior au- species are mature in May and June, with mature thor's tenure with the USDA, Forest Service , females persisting into August. However, we did Northeastern Forest Experiment Station, 180 not closely measure temporal succession at any Canfield Street, Morgantown, West Virginia . Dr. one site where two or more species were found . Andrew Liebhold, USDA Forest Service, Mor- Nevertheless, our data lends support to Enders ' gantown, West Virginia, assisted with data anal - hypothesis that species segregate by habitat . yses. One possible reason for habitat segregation b y Metaphidippus species is competition for similar LITERATURE CITED sized prey. However, with general collections such Allen, D. C., F. B. Knight & J. L. Foltz. 1970. In- as ours, the morphological information of th e vertebrate predators of the jack-pine budworm , specimens themselves is often the only data that Choristoneura pinus, in Michigan . Ann. Entomol. can be analyzed. Prosomal size differences were Soc. America, 63 :59-64. statistically significant among all but one of th e Berry, J. W. 1970 . Spiders of the North Carolina six species-pair combinations, but it may not b e piedmont old-field communities . J. Elisha Mitchell ecologically significant . In the laboratory, Homer Sci. Soc., 86:97-105. & Starks (1972) found that the average percent - Bradley, G. A. & J. D. Hinks. 1968. Ants, aphids , age difference of prosomal length between molts and jackpine in Manitoba. Canadian Entomol ., 100: ofMetaphidippus galathea (Walckenaer) was 18% 40-50. (Dyar's constant). Dyar's constant has bee n Den Hollander, J. & H. Lof. 1972. Differential use (Clerck) and Par- m of the habitat by Pardosa pullata evoked as a means of determining the minimu dosa prativaga (L. Koch) in a mixed population . difference in ecological isolation for prey size Tijdschrift Entomol ., 115 :205-215 . among different instars of a spider species (En- Dondale, C . D., B. Parent & D. Pitre . 1979. A 6-year ders 1976). The same explanation should ac- study of spiders (Araneae) in a Quebec apple or- count for size differences among closely related chard. Canadian Entomol ., 111:377-380. species. The greatest percentage difference among Drew, L. C. 1967. Spiders of Beaver Island, Michi- prosomal measurements in the species pairs dis- gan. Michigan State Univ., Publications of the Mu- cussed here was less than 13% (M. arizonensis seum, Biological Series 3 :152-208. vs. M. protervus) . Assuming that the average per- Enders, F. 1975. The influence of hunting manner on prey size, particularly in spiders with long attack cent difference (18%) between instars of M. gal- distances (Araneidae, Linyphiidae, and Salticidae) . athea also applies to species of Metaphidippus American Nat ., 109:737-763. found in Minnesota, then prosomal size differ- Enders, F. 1976. Size, food-finding, and Dyar's Con- ences among species apparently were not signif- stant. Environ. Entomol., 5 :1-10. icant in determining ecological isolation . We Greenstone, M . H. 1980. Contiguous allotopy ofPar- conclude that these species show a potential of dosa ramulosa and Pardosa tuoba (Araneae: Lycos- competing for similar sized prey based on th e idae) in the San Francisco Bay Region, and its im- absence of appreciable size differences . plications for patterns of resource partitioning in the This paper demonstrates that species of Me- genus. American Mid. Nat., 104:305-311. . Prey, cannibalism, and micro- taphidippus occupy different habitats in Minne- Hallander, M . 1970 habitat selection in the wolf spiders Pardosa chelata sota. Size differences among the Metaphidippu s . Muller and P. pullata (Clerck). Oikos, 21 :337- - O. F species apparently are not great enough to pre 340. vent competition for similar sized prey . Other Homer, N. & K. J. Starks. 1972. Bionomics of th e approaches, including experimental studies , jumping spider Metaphidippus galathea . Annals En- should provide some answers as to how habitat tomol . Soc. America, 65 :602-607. separation is maintained . Ives, W. G. H. 1967. Relations between invertebrate

CUTLER & JENNINGS—HABITAT SEGREGATION OF METAPHIDIPPUS 93

predators and prey associated with larch sawfly egg s Robinson, J. V. 1981 . The effect of architectural vari- and larvae on tamarack . Canadian Entomol ., 99: ation in habitat on a spider community : experi- 607-622 . mental field study . Ecology, 62:73-80. Jennings, D . T. 1976. Spiders on black walnut . Amer- SAS Institute. 1985. SAS User's Guide: Statistics, ican Mid. Nat., 95 :111-119. Version 5 Edition. SAS Institute, Cary, North Car- Jennings, D. T. & J. A. Collins . 1987a . Spiders o n olina . red spruce conifer foliage in northern Maine . J. Ar- Schoener, T . W. 1974. Resource partitioning in eco- achnol., 14:303-314. logical communities . Science, 185 :27-39. Jennings, D . T. & J. A. Collins. 1987b. Coniferous- Stiettenroth, C. L. & N. V. Horner. 1987. The jump- habitat associations of spiders (Araneae) on red ing spiders (Araneae: Salticidae) of the Virginia Pen - spruce foliage. J. Arachnol., 14:315-326. insula. Entomol. News, 98 :235-245 . Legner, E. F. & E. R. Oatman . 1964. Spiders on appl e Stratton, G. E., G. W. Uetz & D . G. Dillery. 1979. in Wisconsin and their abundance in a natural an d A comparison of the spiders of three coniferous tree two artificial environments. Canadian Entomol. 96: species . J. Arachnol., 6:219-226. 1202-1207 . Turner, M . & G. A. Polis. 1979. Patterns of coexis- Lowrie, D . C. 1968. The spiders of the herbaceou s tence in a guild of raptorial spiders . J. Anim. Ecol., stratum of the Jackson Hole region Wyoming . 48:509-520. Northwest Sci., 42:89-100. Vlijm, L . & A. Kessler-Geschiere. 1967. The phe- Lowrie, D. C. 1973. The microhabitats of western nology and habitat of Pardosa monticola, P. nigri- wolf spiders in the genus Pardosa. Entomol . News , ceps, and P. pullata (Araneae, Lycosidae) . J. Anim. 84:103-116 . Ecol., 36:31-56. Mason, R. R. & H. G. Paul. 1988 . Predation on larvae Vogel, B. R. 1972. Apparent niche sharing of two of douglas-fir tussock moth, Orgyia pseudotsugat a Pardosa species (Araneida: Lycosidae) . Armadillo (Lepidoptera : Lymantriidae), by Metaphidippus Papers 7, 13 pp . aeneolus (Araneae: Salticidae) . Pan-Pacific Ento- Young, O . P. & T. C. Lockley . 1990. Autumnal pop- mol., 64:258-260. ulations of on aster and goldenrod in the Richman, D. & B. Cutler . 1978 . A list of the jumping delta of Mississippi . J. Entomol. Sci., 25:185-195 . spiders (Araneae: Salticidae) of the United State s and Canada. Peckhamia 1:82-109 . Manuscript received February 1992, revised March 1992 .