eae ae : ’ id hi a COMP. Zope NIVERSITY OF KANSAS Je eat MISCELLANEOUS USEUM OF NATURAL HISTORY Pua Or as ce Internal Oral Features of Larvae from Eight Anuran Families: Functional, Systematic, Evolutionary and Ecological Considerations By - Richard Wassersug UNIVERSITY OF KANSAS LAWRENCE 1980; Wassersug, E. 1980. UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY The University of Kansas Publications, Mu: wu. .° Natural History, beginning with volume 1 in 1946, was discontinued with volunie 2u in 1971. Shorter research papers formerly published in the above series are now published as Occasional Papers, Museum of Natural History. The Miscellaneous Publications, Museum of Natural History, began with number 1 in 1946. Longer research papers are pub- lished in that series. Monographs of the Museum of Natural History were initiated in 1970. 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COMP ZOO nf THE UNIVERSITY OF KANSAS MuSEUM OF NATURAL HISTORY MIsCcELLANEOUS PUBLICATION No. 68 June 24, 1980.22 Internal Oral Features of Larvae from Eight Anuran Families: Functional, Systematic, Evolutionary and Ecological Considerations By RICHARD WASSERSUG Department of Anatomy and Committee on Evolutionary Biology University of Chicago Chicago, Illinois 60637 THE UNIVERSITY OF KANSAS LAWRENCE 1980 UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY Editor: E. O. Wiley Miscellaneous Publication No. 68 pp. 1-146; 37 figures Published June 24, 1980 MusEuM oF NATURAL HIsTOoRY THE UNIVERSITY OF KANSAS LAwreENce, Kansas 66045 U.S.A. PRINTED BY UNIVERSITY OF KANSAS PRINTING SERVICE LAWRENCE, KANSAS CONTENTS NER © CANO Noe ee ke ee OL 1 IN CKO WAC GL OCTETS a eee og ee, dO I, SR RS 2 INA te ra a Sa aR or a 2 IVA En CS se Bence foe a IE Re Re ee EY 5 EGS GEM ONS 3 2a Pes oe oyre a teen eyo nn Be eR, BO AI ae 1 PS CAD MCA Coe sk SA SO te at nw hs rape RRR il SSCA PIMUSSETUCT Sti Sh REIS UO ASTER SRT oe ares 7 DISCO GIO SSE ASS en ee Sener Re re ee ee Sanne eee oe ae 10 VV TLE SRODSTCETEC ONS fetes a ott ie coe PL Oe eee eR ee eee 10 PAU ECSCISLCTIVUSUE Po I NEE ROT REE ERO De ee 14 BOMMDINGOTICIL GUS cen te Pea ee a ede re ee eee ee 16 IDISCOLLOSSUSIIICLIST wemmas Stet lees peri sweeties ors Seve cae t eee eee 19 iT Op latyani Gaey tar ses oe eae a ke 21 inopliny mus YdOrsalisne 22 ie sek se 7h eee ee cree 2 Mircrolaylidae ye ai oe tee soe ae Sr re OE aes ce eee ae 24 Microhylaiibend more mea ean ae a ee 24 Microhiylathe ymonst ae Te a OH IVGCrON La ORIOL see ee cere RS =e ene ar Re 30 J PCE OFE 6 Patina ter ser weet sa Oe one tees ot Soe 9 ee oh ll 32 SOTO ODES DOM OG RODS ae 32 WOLD O GUS OLD OL eae OR SE AI eo eS Oe eee 33 IC DLObTAChitm@ NASSC big ses ee ate Sees Se ee 37 NEC LOD TACT UAV TIVROS ive 1151S) eereeeeen es eae aaa 40 Orcolalaxiping) oo ER NE nee Aero eerie 43 sli Ge, seme: 20S IRS Aa te Pee ALES ee Eee EE oe 46 ANOCCCU SPINOSG: 2 \e see ee TSE 2 ee ee 2 eee 46 Gasirotheca tiobainbae =-t2. 222 a ee ee ee ee 48 IPO LCD gh CNIUON LUGS) =e ceo tg a a8 ee oes ee ee 52 EUG: AULPOCCUG 23 Sse a een aN tae ee Rca a te 55 LLG OMAN OSCONLG. spss. crn DE Ota ee 59 HGlagpnicbodes xxx. 2 ne. ee, = ee ee oe SP es 61 ALU INA Ce eS te Nc ae Scere re eo eo 63 LUGS CIT OCC GEG 3 ee ws ce we eg ec ne ee 67 ELD ESQ COUCIISLS ox. cee Rs eas. oc ae Pann Mts eR pe esa ae 70 TEAC OND, SOMO OUD, ake EE oe 72 Rigchonlaniconhardschtltcet mess 2: = = aaa enna ae nen 76 UNCTUS CREPUGIS® Sains Se eae na Ne ac ee 80 STUAS CU SOT DUA sxe eet OO 82 VNCGIU CIS COLA TH GS seas ae es 85 Gentrolenid ae’ eee ee oe i ee as See 88 Gentrolenclla fleischnann = ee eee 88 Mendrobatidae 2 8 oat a om aie 91 (ODUGSITA TIS STO OTIC ee ee 91 Golostethis:-niutbicola ess 2 2-2 s Se eee cae eee 94 DISCUSSION (eS eee eee 97 Functionally ConsiGeratiOns) ee ree ee 97 Kératinized structures 2.20.4... eee 97 Infralabial papillae... 4.3. eee 98 Lingual. papillae. ee See 99 Buccal floor atena 2.22.5) 2 ee eee 99 Buccal (pockets: 25...2. 2 ee 2 ee 100 Prepocket papillae and other features of the buccal floor 101 Ventral) velum 00.2 a ON ee 102 The filter system. 2 105 Branchial tood traps andusecretony dees) 22. saan 109 Glottis ‘and laryngeal disc 0.00. ne 110 Esophageal: funnel 2 2 2 eee TE Prenarial arena, 2.8.0 os he 111 Inteimalonares: 22 2k ee 112 PRostnanal arena. 2.8 22ers 113 Kateral ridge papillae <2. 222 ee 114 Buccal root arena’ 24.223 2 3.08 As 114 Glandularzone and dorsal’secretory pits= 115 Dorsaleve luiniyest2e es caesar ee PReenL eee ene 116 Pressure .cushiOns)....2. 8 ee sate SystematicConsiderations 2.22.24 eee 117 Ascaphidae)! 222 2000 22 ee 118 Discoglossidac! (fi. 0 2 ae 118 Rhinophrynidae 220 ee 118 Microhylidaet 272. 2 et ee 118 Relobatidae sre. ee Oe le 119 13 G6 Y= es ets te Be La ON A PAM ery AT 119 Dendrobatidae and’ Centrolenidac a= = 12] EVoluttonanya@onsiderations | 2s eee oe 12] The Ascaphus and Leiopelma lite cycles) eee 2h Evolutionanystrends inthe Discoglossidac. 122 dhe Pipoidea and their relationships 2... 2 123 the ‘microhylid* problemi 2.6 eee 124 The origins of the “advanced” anurans (Type 4 larvae) 125 Evolution of specific larval types in the genus, Hyla _-_-_-___- 126 The evolution of ontogenies and its role in larval diversity 127 Ecological’ Considerations: 22 2 TS Eee 128 Tadpoleteedine ecology... 220 er 128 Rarticle/sorting) the general mechanism 2 a 129 Microhabit implications of morphological patterns — 130 SUMMARY AND" CONCLUSIONS 02S 133 LITERATURE CVRE D2: os eye ee ee 139 APPENDIX: GLOSSARY OF TERMS INTRODUCTION It has been a full century since a biologist first studied tadpole morphol- ogy for clues to the evolution and sys- tematics of the Anura (Lataste, 1879). Generally recognized as the most signifi- cant work from these last hundred years is that of Orton (1953, 1957), who sorted all frog families into four groups based on larval characters, specifically external oral features and spiracle position. While herpetologists have largely ac- cepted Orton’s four superfamilial groups, there is continual disagreement about relationships between and within these groups. Controversies have centered on the question of how much weight should be given larval characters when larval morphologies suggest relationships dif- ferent from adult morphologies. Resolu- tion of this question has been hampered by the few larval characters which her- petologists have traditionally considered to have taxonomic value. With considera- tion of few characters, the chance of convergence is obviously high and con- fidence in derived systematic relation- ships is low. Until recently, most work concerning the higher relationships of anurans has involved only a few tadpole external characters. Starrett (1968, 1973) and Sokol (1975, 1977a, 1977b) have now made much progress toward establishing the importance of tadpoles to anuran systematics. Although they have identified many new internal larval features of value to systematic discus- sions, the larger controversy, unfortu- nately, has not been resolved. Starrett and Sokol disagree on how to interpret relationships implied by many larval features. The present study began as a search for additional diagnostic characters to help clarify systematic problems in the Anura (Wassersug, 1976a). It has ex- panded into a more general, comparative study of the functional morphology and feeding ecology of anuran larvae. An effort is made here not only to identify characters with systematic import, but to discern patterns in oral features that can be correlated with our knowledge of tadpole ecology. I present here a comparative study of certain internal oral features of anu- ran larvae that have not been empha- sized by Starrett, Sokol, or other work- ers. The characters described are all surface features which lie between the opening of the mouth and the esopha- gus. I have emphasized those organs which come into direct contact with water and food in the mouths of tad- poles and are thus directly involved with the feeding process. I have chosen to examine morpholog- ical structures involved in feeding in part because they are convenient to study. The morphology of tadpoles is dominated by tissue related to feeding functions, especially ingestion, and it seems reasonable to assume that a tad- pole’s oral morphology will demonstrate adaptation to the environment in which a larva lives. If we understand the adap- tive significance of morphological fea- tures, we should be able to determine much about the ecology of the tadpole from its oral morphology. An ultimate goal of this comparative study is to un- derstand the morphology of anuran larvae in enough detail to be able to accurately predict a tadpole’s ecology from its morphology. Although this study is limited to sur- face features, some reference is made to underlying, cartilaginous elements such as the ceratohyal, which forms the pis- ton of the tadpole buccal pump, and the spicule, which supports part of the oral surfaces. A comparative study of the cartilaginous skeleton of the tadpole buccal pump is presented elsewhere (Wassersug and Hoff, 1979). Only free-living larvae are consid- ered. An ontogenetic series of one spe- cies, Hyla regilla, was examined in detail in a previous study so that morpho- 2 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY logical features modified extensively through development could be elimi- nated from further consideration (Was- sersug, 1976b). It was necessary to do this because not all material available for study is of the same developmental stage. The core of this paper is descriptions of oral structures in the larvae of se- lected anuran species. This is followed by a four part Discussion. The first part of the Discussion (Functional Considerations) reviews the diversity of the structures, and an effort is made here to correlate known larval ecology with patterns in oral morphol- ogy. Functions for many of the oral structures presented in the Descriptions are deduced on the basis of what is known about larval ecology. The sec- ond part of the Discussion (Systematic Considerations) examines specific sys- tematic questions. The third part (Evo- lutionary Considerations) deals with questions of evolutionary history as well as the evolutionary mechanisms that could account for diversity among tad- poles. The last part of the Discussion (Ecological Considerations ) reverses the first part. Here, starting from a basic understanding of the morphology, an attempt is made to assess the ecology of tadpoles and correlate ecological pat- terns with known morphological pat- terns. ACKNOWLEDGMENTS This paper augments work presented in a doctoral thesis submitted to the University of Chicago in 1973. I want to thank the members of my committee, James Hopson, Robert Inger, George Rabb, David Wake and Rainer Zangerl, for their encouragement, advice, and most of all, their patience. I am grateful to William Duellman, Hymen Marx and David Wake for al- lowing me to dissect specimens in their care. Additional specimens were gener- ously provided by E. Crespo, M. Delsol, R. Demmer, W. R. Heyer, R. W. Mc- Diarmid and C. Richards. For logistical support I thank the Di- rectors and Department Heads of the Committee on Evolutionary Biology and the Department of Anatomy of the Uni- versity of Chicago; the Center for Grad- uate Studies and the Division of Rep- tiles, Field Museum of Natural His- tory, Chicago, and The Museum of Natural History at the University of Kansas. Financial support was provided by a fellowship from the Center for Graduate Studies, Field Museum of Natural His- tory; Block Fund and Hinds Fund, Uni- versity of Chicago; and the National Science Foundation (BMS 75-03447 and DEB 76-19275). I am extremely grateful to Marsha Greaves, who executed drawings for this paper. Ilse Hecht graciously pro- vided translations of several articles in foreign languages. Shirley Aumiller and Robert Kott helped with photography, portions of the manuscript were typed by Debra Randall and Karen Rosenberg. Special thanks are due Nancy Bradney, who helped in many aspects of produc- tion and editing. Steve Busack, William Duellman, Robert Inger, Dianne Seale, Otto Sokol, Linda Trueb and David Wake have read various portions of this manuscript; it has profited greatly from their constructive criticisms. MATERIALS Oral structures of larvae of 31 species from eight families are described. The tadpoles came from museum collections or the author’s private collection. An effort was made to examine specimens at or near Gosner (1960) stage 36. A few species (e.g. Acris crepitans) were chosen for study because they have the commonest type of anuran larvae (i.e., denticle pattern 2/3; inhabitants of small ponds and pools) and serve as reference forms for comparison with tad- poles of more exotic morphologies and ecologies. All other species were selected ORAL FEATURES OF LARVAE FROM EIGHT ANURAN FAMILIES 3 either because they came from families whose larvae have been associated with interesting taxonomic problems or be- cause they present unusual larval ecolo- gies. Particular emphasis was placed on the frogs assigned to the superorder Ar- chaeobatrachia by Duellman (1975); thus Ascaphus (Ascaphidae), Alytes, Bombina, Discoglossus (Discoglossidae ), Rhinophrynus_ (Rhinophrynidae), and several pelobatid larvae are described. Since the Microhylidae is a family of particularly problematic relationships, several Microhyla larvae are also de- scribed. Hylidae larvae were selected because of their great ecological diversity (see Duellman, 1970) while one member of the Centrolenidae and two species of Dendrobatidae are described solely be- cause of their unusual larval ecology. Certain families are not treated here because species from these families have been described or illustrated elsewhere: for example Pipidae (Sokol, 1975, 1977a and other references cited therein); Ran- idae [Rana agilis (Kratochwill, 1933), Rana temporaria (Savage, 1952; De- Jongh, 1968), Rana catesheiana (Grad- well, 1970, 1972a), Rana fuscigula (Gradwell, 1972c)], and the Pseudidae (Pseudis paradoxa larvae illustrated by W. Parker, 1881). One bufonid, Bufo bufo, has been partially described and illustrated by Savage, 1952. The avail- ability of specimens set some constraint on the families that could be studied; several major families with tropical dis- tributions (e.g., Leptodactylidae and Hyperolidae) are left for future work. Knowledge of the habitats and feed- ing ecology of the larvae studied here is summarized below. The species are loosely grouped by common features either of external morphology or ecol- ogy (references for most of these com- ments are given in the descriptions). BENTHIC LARVAE WITH ENLARGED SUCTORIAL MouTHS ASCAPHIDAE.—Ascaphus truei: ad- here to rocks in streams; well known for their large suctorial oral disc and adap- tation to torrential habitats. PELOPATIDAE. — Leptobrachium hasselti: inhabit quiet, clear regions of streams, where they graze on algae growing on rocks. In terms of body shape or tail length, L. hasselti larvae are little specialized for stream life, and are among the more generalized mego- phrynine tadpoles. Leptobrachium osha- nensis: more specialized to stream life than L. hasselti (Liu, 1950:191-201) since larvae have very long, strong tails and are good swimmers in running wa- ter; they stay on the bottom in shallow water and have an expanded oral disc, with a large denticle-free area.1 Oreo- lalax pingii: similar to Leptobrachium larvae in general appearance; described as “bottom feeders” (Liu, 1950). Their morphology suggests that they are inter- mediate in their tolerance for currents between L. hasselti and L. oshanensis. HYLIDAE.—Hyla mixe: among the most highly specialized larvae for stream life; have very large oral disc used for adhering to rocks in strong currents. Ptychohyla leonhardschultzei: inhabit small, quiet, peripheral pools in moun- tain streams. Smilisca sordida: inhabit streams, but only in regions of very gentle current; externally, they show few of the modifications characteristic of stream tadpoles. *Liu (1950:200) questioned the common interpretation (after Smith, 1926) that the mouth serves an adhesive function. He watched an L. oshanensis larva in his laboratory and noticed that when it rested on the bottom, only the tips of the marginal papillae touched the substrate. Water flowed into the mouth through the notch at the front and the back of the disc. Liu then concluded that the oral disc served the function of raising the head off the bottom to allow for respiration. His observations, however, remain inconclusive for the natural situation, because he described the action of the disc only in tadpoles confined to quiet water. The disc may still have an adhesive function in currents, not only for this species, but for all other species with enlarged oral discs. 4 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY FUNNEL-MOUTHED TADPOLES MICROHYLIDAE.—Microhyla hey- monsi: inhabit quiet pools and feed on particles at the air-water interface; have rapidly vibrating, filamentous tail tip and can remain seemingly motionless at the surface film for long periods of time. PELOBATIDAE.—Megophrys — mi- nor: epitomize the surface film-feeding way of life; have a huge, upwardly di- rected, denticle-free oral disc;? occur in slow, flowing water and are, consequent- ly, equipped with a long, powerful tail which allows them to resist displacement downstream. HYLIDAE.—Ptychohyla — schmidto- rum: moderately specialized for stream existence; found in the quieter reaches of mountain pools; have expanded oral discs with a large denticle-free area. DENDROBATIDAE. — Colostethus nubicola: In aquaria they swim beneath the surface film (Savage, 1968). They have a large, anterior-directed oral disc with surface papillae which, according to Savage, aid in sorting particles from the water. Found under vegetation and rocks in side pools and rivulets of small streams; found in pools sufficiently small so as to be occupied rarely by fish. “FOSSORIAL’ STREAM FORMS CENTROLENIDAE.—Centrolenella fleischmanni: extremely elongated larvae which lack the suctorial mouth or fun- nel of other stream forms; found in cracks and crevices amongst the rocks and vegetation in shallow streams. HYLIDAE, Arboreal Larvae.—Ano- theca spinosa: live in the shallow water that collects in tree holes; known carni- vores with large beaks; specialized for feeding on mosquito larvae, other ar- thropods, and frogs’ eggs. Hyla dendro- scarta: extremely elongated tadpoles which live burrowed in the leaf axils of bromeliads; macrophagous (according to Orton, 1944) but lack the large mouth of Anotheca spinosa and presumably are more dietary generalists, feeding on small fragments of animal and _ plant matter that collect in their arboreal pond. MiIpWATER MACROPHAGOUS LARVAE MICROHYLIDAE.—Microhyla berd- morei: dispersed throughout the water column in quiet pools; lack keratinized mouth parts and are obligate feeders on fine, suspended matter. Microhyla or- nata: found suspended throughout the water column; presumably similar in their feeding habits to M. berdmorei. HYLIDAE.—Agalychnis _ callidryas: by rapidly vibrating the pointed tips of their tails these larvae can hang sus- pended in midwater in ponds; retain the typical hylid 2/3 denticle pattern and can facultatively graze on substrates be- sides feeding on microscopic particles midwater (see pers. comm. by McDiar- mid in Heyer, 1976:22). TEMPORARY PooL DWELLERS, Omnivores RHINOPHRYNIDAE. — Rhinophry- nus dorsalis: larvae lack keratinized mouth parts for biting or scraping, but are omnivores able to cannibalize small- er individuals and also efficient suspen- sion feeders of ultraplanktonic particles. PELOBATIDAE.—Scaphiopus bom- bifrons: active tadpole found in tempo- rary pools and known for rapid develop- ment and voracious feeding habits. Al- though carnivorous and cannibalistic, best considered omnivores; an oral disc of moderate size surrounding large and powerful beak; members of genus are efficient suspension feeders (Richmond, 1947). ADDITIONAL Ponp LARVAE DISCOGLOSSIDAE.—Alytes obste- * According to Liu (1950:191) the disc folds shut when the tadpole is below the surface, but opens to form a funnel at the surface film when the tadpoles are feeding. The funnel may function in both feeding and respiration as a surface float; literature on the subject has been reviewed by Noble (1927) and Liu (1950). ORAL FEATURES OF LARVAE FROM EIGHT ANURAN FAMILIES 5 tricans: typical for quiet water tadpoles in general appearance and behavior; able to stay in midwater by gulping air inter- mittently, but feed on vegetation at or near the bottom. Alytes cisternasii: pre- sumably similar to A. obstetricans. Bom- bina orientalis: occur in assorted ponds or pools, often adjacent to streams; can be found in puddles lacking macroscopic vegetation; can be carnivorous. Perhaps appropriately viewed as omnivores with generalized external structures, capable of carnivory and suspension-feeding on microscopic particles. Discoglossus pic- tus: generalized pond larvae, presum- ably similar to Alytes and Bombina. HYLIDAE.—Gastrotheca riobambae: inhabit shallow, high elevation pools and exhibit no unusual behavior for anuran larvae. Hyla femoralis: midwater forms that live amongst vegetation in pools; have exceptionally high tail fin with terminal filament, but otherwise “typi- cal” in their external morphology and feeding habits. Hyla rufitela: live in small pools, often overgrown with mac- rophytes; have an unusual 2/4 denticle pattern but not known to have unusual feeding ecology. Hyla ebraccata and Hyla sarayacuensis: hide among the aquatic plants of the shallow parts of ponds, where the adults of the species breed; larvae characterized by a reduc- tion of the oral disc and the loss of den- ticle rows as compared with typical pond hylids; members of species group feed on submerged leaves or other de- bris (Starrett, 1973). Hyla phlebodes: found among vegetation in shallower parts of pools; have small mouth without oral disc and denticle rows; members of species group feed on the bottom (Star- rett, 1973). Acris crepitans: typical gen- eralist tadpole of small ponds and pools throughout much of eastern United States. Colostethus nubicola: inhabits small, rocky ponds; details of feeding ecology unknown. METHODS All tadpoles examined were meas- ured from snout to vent and staged ac- cording to Gosner, 1960. For each tad- pole the floor and the roof of the mouth were exposed following a simple dissec- tion procedure described by Wassersug (1976a). Tadpoles were pinned under water in a small tray of darkly stained paraffin and examined with a dissecting microscope. The larvae were lightly stained with either methy] blue or crys- tal violet to accentuate surface features, specifically mucous-secreting epithelia. Ventral and dorsal surfaces were pho- tographed on 4” x 5” format through a bellows-view camera using a 32 mm lens; a few photographs were taken with 16 or 64 mm lenses. Tadpoles were usu- ally pinned to the paraffin at the tail only; care was taken not to distort or stretch oral surfaces. Camera lucida drawings were also made of many of the specimens, particularly the smaller ones. Either camera lucida drawings or photographs accompany the descriptions for most species; some descriptions have both for purposes of comparison. One species is described without photograph or illustration because it is nearly identi- cal to related forms that are illustrated. All illustrations in this descriptive section present the buccal floor and buc- cal roof as a single plate with the floor above and roof below; for drawings, dor- sal and ventral surfaces are magnified equally and a single scale line (=1 mm) is given. For the photographs, a single scale line is given if both halves of the plate are magnified equally; otherwise two separate scale lines are used. Just as there are optical limits on photographical qualities,? there are hu- * An effort was made to obtain scanning electron (SEM) photomicrographs of several small specimens because of the potential resolution and depth of field provided by this technique. SEM, however, had to be abandoned because it required pre-coating the specimens with a uniform, con- ductive metallic layer and the convoluted, intricate structure of the gill filters made such preparation impossible. 6 MISCELLANEOUS PUBLICATION MUSEUM OF NATURAL HISTORY man limits on how accurately certain ventral, pharyngeal features—specifical- ly, the gill filters—can be drawn. The gill filters in many of the drawings are slightly stylized; minor discrepancies be- tween the descriptions and the drawings remain. Species descriptions are grouped by family. Each description is provided with a reference or references that per- tain(s) to the species morphology, ecol- ogy, or both. The morphological descrip- tions follow Wassersug (1976a). Mer- istic features are presented for both the left and right sides of the buccal roof and floor; discrepancies between one side and the other, are noted. These data, which were originally collected to determine whether asymmetries in ex- ternal aspects of the respiratory system (i.e., position of the spiracle) were re- flected internally, give some indication of the amount of variation in any species. Meristic data from the pharynx are all taken from the left side. It can be noted Buccal Floor Arena Papillae Marginal Projection Filter eee pees Cavities I, 01,0 4 ibe e ? Esophageal ——EE here that no consistent pattern of left or right handedness was found, either in- traspecifically (for Hyla regilla; Wasser- sug, 1976b) or interspecifically. Because of the complex, qualitative nature of many of the features described, I chose not to use a telegraphic form for the descriptive body of the study. Hyla regilla, illustrated and described in de- tail in Wassersug (1976b), is treated as the “typical” pond tadpole and consid- ered a reference for comparison with the other forms. Figures 1 and 2 show nearly all structures presented in the species de- scriptions. All morphological structures described are briefly defined in the Glossary. Terminology follows Wasser- sug (1976a). Two sources are followed for anuran systematics. I follow Orton (1957) in recognizing four larval types. Type 1 includes the Pipidae and the Rhinophry- nidae; Type 2 consists of the Micro- Lower Beak Lingual Papillae Infralabial Papilla Buccal Floor Arena Prepocket Papillae Buccal Pocket Filter Rows SEF ete Funnel Glottis Fic. 1.—The floor of the mouth in a Hyla femoralis larva. Most morphological features discussed in the text are labelled in this Figure and Fig. 2. The scale line equals 1 mm. ORAL FEATURES OF LARVAE FROM EIGHT ANURAN FAMILIES 7 Prenarial Arena Prenarial Papillae Postnarial Arena Median Ridge Buccal Roof Arena Lateral Pressure f NSS. Cushion ae Medial Pressure Cushion Esophagus oar acs REP ES Denticle Rows Upper Beak Narial Valve Projection Postnarial Papillae Lateral Ridge Papilla