TAXONOMY, ETHOLOGY, and ECOLOGY of Phidippus (ARANEAE: SALTICIDAE) in EASTERN NORTH AMERICA
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TAXONOMY, ETHOLOGY, AND ECOLOGY OF Phidippus (ARANEAE: SALTICIDAE) IN EASTERN NORTH AMERICA BY GLAVIS BERNARD EDWARDS, JR. A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1980 ACKNOWLEDGMENTS In a work of this scope, it is impossible to individually thank every person who has contributed to its completion, but I do sincerely thank every one of you. I would like to single out my committee members: Dr. W. H. Whitcomb, who tolerated the development of lines of research astray from his own; Dr. Jonathan Reiskind, for his positive reinforcement and assistance; and Dr. T. J. Walker, for demanding excellence. Various types of technical assistance were provided by Mrs. Thelma C. Carlysle, Mr. P. M. Choate, Dr. Jonathan Reiskind, and Dr. Robert Paul. Special thanks are due Mrs. Katrina Vaughanfor typing the manuscript and going to special effort to help make deadlines. For identifications of prey and enemy records I thank Mrs. E. C. Beck, and Drs. W. F. Buren, R. J. Gagne, E. E. Grissell, D. H. Habeck, F. W. Harmston, L. A. Hetrick, K. W. Knopf, P. M. Marsh, F. W. Mead, E. L. Mock- ford, J. C. E. Nickerson, C. W. Sabrosky, R. I. Sailer, L. A. Stange, T. J. Walker, H. V. Weems, Jr., and R. E. Woodruff. Thanks are due the technical staff of the Bureau of Entomology, Division of Plant Industry, for their assistance and encouragement. This list would not be complete without mentioning the dear friends who have put up with me and helped in so many ways: Ron and Peggy Williams, Earl Williams, Allen Mosler, Fred and Peggy Hansen, Anzle Mead, Wanda Weintraub, Ruth Schaeffer, Mary Warren; my parents, Glavis and Margaret Edwards, for their patient and continued support; and most of all, my wife, Sue, who has managed to keep both of us going. TABLE OF CONTENTS PAGE ACKNOWLEDGMENTS ii ABSTRACT v CHAPTER GENERAL INTRODUCTION 1 TAXONOMY OF EASTERN Phidippus 4 Introduction 4 Key to Adult Male Phidippus of the 18 Eastern U. S. Key to Adult Female Phidippus of the 20 Eastern U. S. 22 Subgenus Anipalpus , new subgenus Subgenus Phidippus 27 IMMATURE STAGES OF Phidippus SPECIES 98 HYBRIDIZATION IN Phidippus SPECIES 102 Introduction 102 Methods 103 Laboratory Results 103 Ecological Factors Affecting Hybridization 108 Species Relationships, Geologic History, 111 and Speciation Hybridizations Between Other Species 115 THE COURTSHIPS OF EASTERN Phidippus 117 Introduction 117 Methods, Materials, and Terminology 117 Results 121 Discussion 133 SOUND PRODUCTION BY COURTING MALES OF Phidippus mystaceus (Araneae: Salticidae) 135 Introduction 135 Experimental Procedure 135 Results 136 Discussion 139 Conclusion 144 Additional Observations 145 CHAPTER 7 DIFFERENTIAL ATTACK RESPONSES BY Phidippus SPP. (ARANEAE: SALTICIDAE) TO CONTRASTING PREY TYPES Introduction Materials and Methods Results Discussion INSTINCT AND CONDITIONED LEARNING AS FACTORS IN THE PREY-CAPTURE BEHAVIOR OF NAIVE SPIDERLINGS (ARANEAE: SALTICIDAE) Introduction Methods and Materials Results and Discussion MIMICRY IN Phidippus Introduction Methods Results and Discussion 10 ECOLOGY OF Phidippus SPECIES Abstract of Dissertation Presented to the Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy TAXONOMY, ETHOLOGY, AND ECOLOGY OF Phidippus (ARANEAE: SALTICIDAE) IN EASTERN NORTH AMERICA By Glavis Bernard Edwards, Jr. December, 1980 Chairman: Dr. Willard H. Whitcomb Major Department: Entomology and Nematology The 16 species of Phidippus occurring in the eastern United States are redescribed and illustrated together for the first time. Thirteen of these species occur in Florida. First instars are briefly described for most of these species for the first time. Both field and laboratory hybrids of P. regius x P. otiosus and F backcrosses of hybrid females to males of both parent species are des- cribed. Hybrid males were sterile; hybrid females backcrossed to males of either parent species were significantly less fecund than either parent species. The two species are considered to be advanced sibling species which lack only the late stages of pre- and/or post zygotic isolating mechanisms (behavior and/or complete hybrid sterility) to completely separate each species. The courtship behavior of 13 of the 16 eastern species, as well as the P. otiosus x P. regius hybrid, are described, 8 for the first time. A new method of communication for salticids, sound (made by a stridula- P_. tory mechanism on each palpus) , is reported for mystaceus A combined visual-vibratory display is reported for P_. whitmani . Differences in prey-capture behavior are noted for adult Phidippus prof erred house flies and cabbage looper larvae. Cabbage looper larvae were captured by all species tested from an average distance of 5 - 6 mm, whereas average capture distances of house flies averaged 2-3.5 times this distance, depending upon the species of Phidippus . Prey-capture behavior was noticeably different depending upon the type of prey ap- proached, with a much more stealthy approach used against house flies. Naive spiderlings, in similar prey-capture tests involving other types of prey, were shown to rely at least in part on experience after initial encounters with various prey types. In tests with small ants as the inten- ded prey, the spiderlings initially attacked the ants, but were driven away by the ants. Spiderlings thereafter avoided ants for up to 4 days (the longest test), demonstrating learning of the basic trial-and-error type. That adult Phidippus generally avoid ants both in the field and laboratory is evidence that this type of learning is long-lasting. Preliminary investigations with 2 lizard species indicated that P_. apacheanus was a generalized Batesian mimic of red and black species of the velvet ant genus Dasymutilla (Hymenoptera: Mutillidae) . Nearly all instars of P_. apacheanus exhibited the red and black coloration; mimicry in adult males was most complete, as it included behavioral elements as well as color pattern similarity. Adult males of P_. cardinalis are similar in color to males of P. apacheanus , and can probably also be considered Batesian mimics of Dasymutilla , although other possibilities are examined. Most species were found to occur in several habitats, but dominant in only one, or never dominant. In habitats with more than one domi- nant, the phenology of the dominants was different. Some microhabitat separation was exhibited, both between species and between immatures and adults of the same species. Prey included members of the orders Dip- tera, Hymenoptera, Lepidoptera, Coleoptera, Odonata, Orthoptera, Hemiptera, Homoptera and Araneae. Prey size was significantly correla- ted with spider size. Enemies included pompilid and sphecid wasps, acrocerid and mermithid parasitoids, mantispid and dipteran egg predators, hymenopteran egg parasites, predaceous fungi, frogs, lizards, birds, and other spiders. Mean reproductive rates correlated well with mean length of each species; _P. clarus was an exception. Niche breadth varied widely among species, and overall niche overlap was low among species. Temperature in peninsular Florida probably is less critical than in most temperate areas; however, at least one activity, hunting, ceased at temperatures below 15° C. vii CHAPTER 1 GENERAL INTRODUCTION The present research can be best described as a multi-discipline study of the biosystematics of members of the salticid genus Phidippus in eastern North America, with emphasis on the species occurring in Florida. It is a natural extension and expansion of previous research (on the biology of P_. regius ; Edwards, 1975) and an offshoot of other research (e.g., Whitcomb et al., 1963) implicating species of Phidippus and other salticids, as well as many other spiders, as important preda- tors in agro-ecosystems. The final organization is in reverse order from how the research was initially conceived, from a study of the ecology of each species to a comparison of certain behaviors to the redescriptions and phylogenetic relationships of the species. The taxonomic section is presented first to introduce and describe the species. It is followed by ethological research, some of which (courtship behavior) is directly related to the phylogeny. The ecology section describes the phenology and both faunal and floral associations of the species. Finally, all three sections are interwoven to form an overview of the genus. Adult Phidippus are medium to large spiders (Figure 1-1) and often brightly colored. Generally they are docile spiders, which will attempt to hide or flee if threatened by the proximity of a human. Some can be easily handled; the specific epithet of one species (audax , meaning bold or audacious) was used to describe the manner of one of these spiders which would hop onto a person's hand if the hand was placed down carefully near the spider. That they can and will bite if carelessly handled is demonstrated by numerous reports in California of people in the U. S., other bitten by P_. formosus (=P. johnsoni ). Elsewhere species occasionally have been reported to bite humans, to which I pain of the bite can personally attest in the case of P. regius . The more is light to moderate and of short duration, usually not lasting about human than a few minutes. At least three species occur commonly the dwellings: P. johnsoni along the west coast, P. audax throughout eastern and central states, and P.