PHYLOGENETIC and BIOGEOGRAPHIC PATTERNS of BASILISCINE IGUANIANS (Reptilia: Squamata: "Iguanidae")

© Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at PHYLOGENETIC AND BIOGEOGRAPHIC PATTERNS OF BASILISCINE IGUANIANS (Reptilia: Squamata: "Iguanidae") 3 \9$ BY MATHIAS LANG BONNER ZOOLOGISCHE MONOGRAPHIEN, Nr. 28 1989 Herausgeber: ZOOLOGISCHES FORSCHUNGSINSTITUT UND MUSEUM ALEXANDER KOENIG BONN © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at BONNER ZOOLOGISCHE MONOGRAPHIEN Die Serie wird vom Zoologischen Forschungsinstitut und Museum Alexander Koenig herausgegeben und bringt Originalarbeiten, die für eine Unterbringung in den „Bonner zoologischen Beiträgen" zu lang sind und eine Veröffentlichung als Monographie rechtfertigen. Anfragen bezüglich der Vorlage von Manuskripten sind an die Schriftleitung zu richten; Bestellungen und Tauschangebote bitte an die Bibliothek des Instituts. 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Rheinwald Zoologisches Forschungsinstitut und Museum Alexander Koenig Adenauerallee 150—164, D-5300 Bonn 1, Germany Druck: Rheinischer Landwirtschafts-Verlag G.m.b.H., 5300 Bonn 1 ISBN 3-925382-28-3 ISSN 0302-671X © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at PHYLOGENETIC AND BIOGEOGRAPHIC PATTERNS OF BASILISCINE IGUANIANS (Reptilia: Squamata: "Iguanidae") BONNER ZOOLOGISCHE MONOGRAPHIEN, Nr. 28 1989 Herausgeber: ZOOLOGISCHES FORSCHUNGSINSTITUT UND MUSEUM ALEXANDER KOENIG BONN © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at CIP-Kurztitelaufnahme der Deutschen Bibliothek Lang, Mathias: Phylogenetic and biogeographic patterns of basiliscine Iguanians (Reptilia: Squamata: "Iguanidae") / by Mathias Lang. — Bonn: Zoolog. Forschungsinst. u. Museum Alexander Koenig, 1989. (Bonner zoologische Monographien; Nr. 28) ISBN 3-925382-28-3 NE: GT EPIGRAPH Sibilaque effundens cunctas terrentia pestes, Ante venena nocens, late sibi submovet omne Vulgus, et in vuca regnat Basiliscus arena. But fiercely hissing through the poison'd air The Basilisk exerts his deathfull glare: At distance bids each vulgar pest remain, And reigns sole monarch of his sultry plain. Lucan (A.D. 39—65) © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at CONTENTS Page Abstract 5 Introduction 5 Introduction to the "Iguanidae" 5 Historical Review of the Basiliscines 6 Goals and Problems of this Study 7 Factors Important to the Development of this Study 7 Basiliscine monophyly 9 Methods and materials 15 Specimens 15 Outgroup Analysis 15 Character Definitions 32 Problems of Variation 33 Description of cranial skeleton 34 Nasal Capsule 35 Palate 42 Orbital Region 48 Temporal Region 54 Posterior Brain Case 65 Lower Jaw and Hyoid 68 Miscellaneous Cranial Characters 79 Description of postcranial skeleton 82 Vertebral column 82 Ribs and rib articulation patterns 88 Pectoral girdle 90 Pelvic girdle 95 Appendicular skeleton 97 Description of Internal Anatomy 98 Myology 98 Hemipenes 101 Description of External Morphology 102 Squamation 102 List of systematic characters 103 © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at 4 .Discussion 113 Phylogeny 113 Diagnosis of taxa 116 Basiliscus 118 Corytophanes 1 3 3 Laemanctus 141 Biogeography 148 Phylogenetic affinities with other "iguanids" 154 Summary and conclusions 156 Resumen 157 Acknowledgments 158 Literature cited 159 Appendices 167 A. List of specimens examined 167 B. Key to the species 171 © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at 5 ABSTRACT As presently understood, the "Iguanidae" is composed of eight suprageneric, monophyletic clades, the interrelationships of which are unresolved. The phylogenetic relationships within one of these clades, the basiliscines, is investigated herein. Basiliscine "iguanids" comprise nine semiarboreal to arboreal species placed in three genera - Ba- siliscus, Corytophanes, and Laemanctus - which range from northwestern Mexico, through Central America to Venezuela. The monophyly of the group is well substanti- ated within the context of "Iguanidae". Data for phylogenetic analysis are from osteo- logical characters and soft anatomical features. Behavioral and ecological observations are included for all terminal taxa. The analysis was performed using a "functional outgroup consensus approach" in which the other seven "iguanid" clades were treated as unresolved functional outgroups. The results of the analysis indicate that each of the three genera is monophyletic, and that Corytophanes and Laemanctus are more closely related to one another than either is to Basiliscus. Within Basiliscus, the relationships are not completely resolved. Basiliscus plumifrons and B. basiliscus are one another's closest relatives and form a tritomy with B. galeritus and B. vittatus. Within Coryto- phanes, C. percarinatus and C. cristatus are each others closest relatives. INTRODUCTION Introduction to the "Iguanidae" "Iguanidae" is the largest and most widespread family of non-ophidian squamates in the New World. Within extant squamates it is an early diverging taxon (Estes et al. 1988), comprising approximately 60 genera containing more than 600 species. Gauthier (1984), indicated that "iguanids" is a metataxon, i.e. a group for which there is no character evidence supporting either monophyly, paraphyly or polyphyly and used an as- terisk following the taxon name. In this study the traditional quotation marks are used to indicate that this taxon is not a clear-cut monophyletic unit. "Iguanids" have a very extensive and curious geographic distribution. In the New World, "iguanids" range from southern Canada through North and Central America to Tierra del Fuego at the tip of South America. They also occur throughout the West Indies and Galapagos. They are found on Madagascar, the Comoro Islands, and on the islands of the Fiji-Tonga group in the South Pacific. This distribution poses some interesting zoogeographical questions (Renous 1979; Moody 1980; Blanc et al. 1983; Estes 1983a, 1983b; Grehan & Ainsworth 1985). Members of this family are adapted to a broad spectrum of habitats. They can be found in temperate, tropical and subtropical areas and occur from extreme deserts to tropical rainforests, from sea level to above the tree line. The fossil record of "iguanids" is scant at best (Estes 1983a) and most fossils referable to the "iguanids" are North American, and do not predate the Eocene (Estes & Price © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zoologicalbulletin.de; www.biologiezentrum.at 6 1973; Estes 1983a, 1983b) except for an undescribed North American Paleocene "iguanid" (Estes, pers. comm.). The basiliscines form a small group of semiarboreal and arboreal squamates, primarily centered in Middle America, but ranging from northwestern Mexico to Ecuador and Venezuela. There are three genera that comprise this taxon: Basiliscus (4 species), Cory- tophanes (3 species) and Laemanctus (2 species). One interesting question raised by the distribution of basiliscines pertains to the zoo- geography of Central America and the origin and possible differentiation of the West Indian herpetofauna (Rosen 1975, 1978; Pregill 1981; Savage 1982; Buskirk 1985). Basiliscines are moderately large lizards (150 to 240 mm snout-vent length, Ahl 1930), with a compressed body and a long, slender tail. The head of all adult basiliscines has a distinctive, vertical, blade-like process of the parietal bone that extends back over the neck. The development of the parietal blade is a unique derived character within the family that has been used repeatedly to diagnose basiliscines. Laemanctus and Corytophanes remain moderately rare in collections, and little is known about their natural history. Both genera are inconspicuous and are essentially sit-and-wait predators, which also reflects their arboreal habits. Basiliscus is a more ac- tive predator, more conspicuous, has a more extensive range, and is therefore better re- presented in collections. There is a moderate amount of literature on the ecology and behavior of Basiliscus, particularly with respect to its terrestrial and aquatic bipedal lo- comotion (see section on diagnosis of taxa). At the species level, the alpha taxonomy of basiliscines is reasonably well-known, al- though some authors still doubt the validity of certain species and subspecies (Peters 1967). Nevertheless, there has been no attempt to assess

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