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Bionomics, Systematics, and Phylogeny of Lytta, a Genus of Blister Beetles (COLEOPTERA, MELOIDAE) Lytta magister, male (drawing by F. Pacheco) Bionomics, Systematics, and Phylogeny of Lytta, a Genus of Blister Beetles (Coleoptera, Meloidae) RICHARD B. SELANDER ILLINOIS BIOLOGICAL MONOGRAPHS: Number 28 THE UNIVERSITY OF ILLINOIS PRESS URBANA, 1960 Board of Editors: william r. horsfall, r. d. de moss, francis j. krui- DENIER, WILSON N. STEWART, AND AUBREY B. TAYLOR THIS MONOGRAPH IS A CONTRIBUTION FROM THE DEPARTMENT OF ENTO- MOLOGY, UNIVERSITY OF ILLINOIS. DISTRIBUTED: DECEMBER 30, 1960. (g) 1960 BY THE BOARD OF TRUSTEES OF THE UNIVERSITY OF ILLINOIS. MANUFACTURED IN THE UNITED STATES OF AMERICA. LIBRARY OF CONGRESS CATALOG CARD NO. 60-15932. Contents Page Introduction 1 Historical Resume 2 Bionomics 2 Systematies 3 Methods and Terms 4 Acknowledgments 6 Bionomics 8 Economic Importance 9 Damage to cultivated plants 9 Medical importance 9 Enemies 10 Activities of Adults 11 Seasonal distribution and longevity 11 General behavior 12 Courtship and mating 14 Oviposition 15 Development of Immature Stages 16 Incubation 16 Number of larval instars 16 Larval hosts 17 First larval instar 19 Grub stage 19 Coarctate larval instar 19 Ultimate larval instar 20 Pupal stage 20 Systematics and Phylogeny 21 Genus LYTTA Fabricius 21 Limits of the Genus 22 Classification 26 Conspectus 26 Basis 27 Old World subgenera 27 Key to Subgenera 28 Phylogeny of the Subgenera 30 Distribution 31 Vi BIONOMICS, SYSTEMATICS, AND PHYLOGENY OF LyttCl Page Artificial Key to the North American Species of Lytta 35 Subgenus PARALYTTA, new subgenus 49 Nitidicollis group 53 Fulvipennis group 57 Variabilis group 61 Variabilis subgroup 62 Koltzei subgroup 73 Quadrimaculata subgroup 84 Reticulata group 101 Reticulata subgroup 102 Deserticola subgroup 108 Magister group 113 Tenebrosa subgroup 115 Melaena subgroup 122 Magister subgroup 127 Subgenus ADICOLYTTA, new subgenus 137 Peninsularis group 141 Eucera group 143 Mutilata group 147 Subgenus POREOSPASTA Horn, new status 157 Stygica group 161 Moerens group 193 Moerens subgroup 194 Cyanipennis subgroup 204 Childi subgroup 215 Subgenus POMPHOPOEA LeConte, new status 222 Polita group 226 Aenea group 228 Sayi group 234 Literature Cited in the Text 240 Index 285 Introduction The genus Lytta, with 128 currently assigned species, is one of the larger genera of the family Meloidae, which is a member of the section Heteromera of the superfamily Cucujoidea of the order Coleoptera. Adult Meloidae, known popularly as blister beetles, are rather slender, soft- bodied, long-legged, phytophagous insects. In the drier subtropical and tropical regions of the earth they form a very conspicuous part of the fauna, feeding gregariously, often in spectacular numbers, and at times causing severe damage to crops. In more mesic regions the family is not so well represented. In the larval stage Meloidae are unusual for Cole- optera in having a parasitic mode of life. Larval hosts are of limited variety: wild bees and grasshoppers. Meloid larvae begin life as active, strongly sclerotized campodeiform insects charged with the responsi- bility of locating their own food materials. In Lytta and a large number of related genera this is achieved by active searching; in other genera phoresy is involved. Developing larvae undergo hypermetamorphosis, passing through four morphologically and behaviorally different phases before reaching the pupal stage. My attention was first drawn to the genus Lytta in the summer of 1950 when, while collecting insects at high elevation in the Wasatch Range of northern Utah, I found adults of the large, metallic greenish blue cyanipennis swarming on one of the native lupines. During this same sum- mer I obtained eggs from some of the adult beetles and subsequently succeeded in rearing larvae of the species through several instars. Later, working in Mexico, I had the opportunity to observe additional species of Lytta in their natural habitats and to secure additional larvae. In selecting the genus for study, I was influenced both by the experience I had had with the group in the field as well as by the knowledge that previously no attempt had been made to define the genus on a world basis, to incorporate both Old and New World species into a scheme of classi- fication or phylogeny, or to revise the species of an entire continent. Further, since the genus stands in the midst of the complex and un- wieldy tribe Lyttini, it seemed to me that a clarification of the limits and composition of the genus would be an especially important contri- bution to the study of the family. Within limits imposed by time and the availability of material, the present study is as comprehensive as it has been possible to make it. A major part is devoted to a revision of the species of Lytta of the North 1 ) 2 BIONOMICS, SYSTEMATICS, AND PHYLOGENY OF Lytta American continent. In the phylogenetic portions of the study the fauna of North America is treated at the specific level, while consideration of the fauna of the Old World is, of necessity, confined to main evolution- ary lines. Similarly, the formal classification includes all the species of the genus in North America but only a part of the species in the Old World, i.e., those represented in collections studied or described rather fully in the literature.