ANATOMICAL EVIDENCE FOR PHYLOGENETIC RELATIONSHIPS AMONG WOODPECKERS WILLIAM R. GOODGE ALT•tOUCr•the functionalanatomy of woodpeckershas long been a subjectof interest,their internal anatomyhas not been usedextensively for determiningprobable phylogeneticrelationships within the family. In part this is probablydue to the reluctanceto use highly adaptivefea- tures in phylogeneticstudies becauseof the likelihood of convergent evolution. Bock (1967) and othershave pointedout that adaptivehess in itself doesnot rule out taxonomicusefulness, and that the highly adaptivefeatures will probablybe the oneshaving conspicuous anatomical modifications,and Bock emphasizesthe need for detailedstudies of func- tion beforeusing featuresin studiesof phylogeny.Although valuable, functionalconclusions are often basedon inferencesnot backed up by experimentaldata. As any similaritybetween species is possiblydue to functionalconvergence, I believewhat is neededmost is detailedstudy of a numberof featuresin order to distinguishbetween similarities re- sultingfrom convergenceand thosebased on phylogenticrelationship. Simplestructures are not necessarilymore primitive and morphological trendsare reversible,as Mayr (1955) has pointedout. Individual varia- tion may occur and various investigatorsmay interpret structuresdif- ferently. Despite these limitations,speculation concerning phylogeny will continuein the future,and I believethat it shouldbe basedon more, rather than fewer anatomical studies. MATERIALS AND METItODS Alcoholic specimensrepresenting 33 genera and 47 specieslisted in Table 1 were dissectedwith the aid of a Zeiss operation microscope. Major items studied include the tongue and hyoid apparatus, salivary glands, certain jaw muscles,and the limb muscles. In order to make direct comparisonsbetween species, an approximate representationof relative size was obtained by the use of a cranial length index, listed for each speciesin Table 1. This was calculatedby dividing the distancc from the nasal-frontalhinge to the posteriorend of the head by the same measure- ment in Dryocopus pileatus. Relative dimensionswere calculated by dividing the actual dimensionin each caseby the appropriatecranial length index. It is hoped that when more specimenshave been studied, the quantitative data can be used in a more sophisticatedmathematical treatment, but in this analysismeasurements were used only in casesof obvious difference. The criticism that too few individuals of a specieswere used may be valid, but in order to gain a better perspectivein this preliminary study, it was decided to examine a large number of features in a representativeseries of genera and species. All too often in previous works er- roneousconclusions were reachedby studying only a few speciesof a group. Some 65 The Auk, 89: 65-85. January 1972 66 WILLIA• R. GoonoE [Auk, Vol. 89 TABLE 1 LIST OF SPECIESSTIJDIED • AND SIJ1VI1VIAR¾O•FCERTAIN FEATIJRES Sartorius origin Iliotib. Cranial post w. Thoracic % il. troc. Species index % biceps spines anterior Jynxtorquilla .59 125 11/.2 41 Picumnuscirrhatus .38 52 3 100 Picumnusinnominatus .41 75 3 65 Nesoctitesmicromegas .53 120 21/..2 53 Sasiaochracea .37 55 3 80 Chrysoptilusmelanochloros .76 91 2I/.2 41 Colapresauratus (4) .85 80-97 2-21/.2 36-83 Piculusfiavigula .63 72 la• 50 Camperherapermlsta .58 49 2 100 Celeusfiavus .73 50 1I/.2 0 Celeussp. (trunk only) -- 58 1V2 0 Celeuselegans .76 54 2 15 Micropternusbrachyurus .70 72 1 0 Picusvittatus .81 69 2I/.2 56 Dinopiumjavanense .76 83 21• -- Meiglyptestristis .61 -- -- -- Mulleripicuspulverulentus 1.19 36 2a• 0 Dryocopuspileatus (2) 1.00 63-81 21/.2 51-66 Dryocopuslineatus .82 66 21• 39 Asyndesmuslewis .74 40 2 0 Melanerpeserythrocephalus (2) .69 38-52 2 100 MelanerpesIormicivorus .68 30 2 100 Centurusstriatus .67 42 2 100 Centuruscarolinus (4) .73 38-47 2-2I/.2 17-67 Centuruspucherani .66 41 2 100 Sphyrapicusvarius .55 32 21• 45 Sphyraplcusthyroideus .54 16 21/• 100 Trichopicuscactorum .55 52 2 -- Veniliornispasserinus .54 66 2V2 100 DendropicosIuscesens .47 49 21• 100 Dendrocoposvillosus .67 52 21/.2 100 Dendrocopospubescens (2) .50 47 2 100 Dendrocoposscalaris .53 25 3 89 Dendrocoposnuttallii .57 67 2 100 Dendrocoposalbolarvatus .62 40 21/'2 74 Picoidesarcticus .66 68 2• 100 Sapheopiponoguchii (trunk only) -- 54 21•2 100 Xiphidiopicuspercussus .66 39 2 66 Mesopicosgoertae .66 51 11/.2 84 Thripiasnamaquus .70 39 21/• 100 Hemicircus concretus .55 105 3 47 Blythipicusrubiginosus .73 74 2•/2 80 Chrysocolapteslucidus .81 61 3 100 Phloeoceastesguatemalensis .87 43 3 100 Phloeoceastesmelanoleucos .91 44 3 100 Phloeoceastesleucopogon .83 68 31/.2 100 Campephilusprincipalis 1.11 49 31• -- Wheremore than onespecimen was examined, the numberis shownin parentheses. January 1972] WoodpeckerRelationships 67 indication of individual variation was obtained where several specimens were studied, particularly for Colaptes and Centurus. For many of the featuresto be considered,additional information was available from published works. Descriptionsof the salivary glands and hyoid apparatus appear in the works of Leiber (1907), Antony (1920), and Steinbacher (1934, 1957). Information concerningadaptations for climbing and pecking has been obtained from the studiesby Burt (1930), Beecher (1953), Bock and Miller (1959), and Spring (1965). For the limb muscles those of Butt, Hudson (1937), Lowe (1946), and Hudson and Lanzillotti (1955) were used. The papersof Lucas (1895) and Scharnke (1931) contain data on the tongue and hyoid horns. For comparison with speciesoutside the family, in addition to use of published information I dis- sectedother specimens,particularly passerines. The muscleterminology employed by George and Berger (1966) has usually been followed, but for the tracheal and hyoid musclesLeiber's terms have been used in some cases. As most of the structures studied are uniformly developed throughout the family and some show intraspecificvariation, of the hundredsof potentially useful features only a few may be of value as phylogeneticindicators. The first part of the dis- cussion that follows considers about 30 features that may have potential value. An attempt has been made to judge whether a feature is "primitive" or "advanced" depending largely on its occurrence in other birds. Occurrence in Jynx or piculets is consideredto be supporting evidence of a feature's primitiveness. The next por- tion of the paper considersgroups of individual genera on the basis of anatomical similarity and interrelationships.More descriptionsand analyses of function es- pecially of woodpecker limb muscles are needed, but this paper discussesonly those structures that may be important for phylogenetic considerationswithin the family. AIVAI•¾SIS 0t' IIVDXVIDtrAI• FEATURES LatisslmusdorsL--Pars anterior (Figure 1) takes origin in woodpeckersfrom the last two cervicalspinous processes and in most speciesalso from the first thoracic. Pars posterior,not previouslyreported in woodpeckers,is presentin Jynx, piculets, Campephilus,and Phloeoceastes(Figure 1). Origin is by an aponeurosisdeep to sartorius. It inserts on the humerus proximal to that of pars anterior. A humeral anchor similar to that describedby George and Berger (1966) is present. The pres- ence of pars posteriorwithout doubt representsthe retention of a primitive feature. Rhomboldeus super)qcialis.--Origin(Figure 1) is from the last cervical spinous processor first thoracic to mainly the third or sometimesthe fourth thoracic spinousprocess. Probably the area of origin has been reducedin woodpeckersas an origin exists from the last cervical in Jynx, Nesoctites,and at least some passerines. In Jynx, Nesoctites, Camperhera, Centurus catolinus, Sphyraplcus varius, Xiphidiopicus,Mesopicos, Blythipicus (Figure 3), and Hemicircusthe musclehas a small insertion on the clavicle as well as the scapula. Rhomboideuspro)•undus.•This muscleis unusual in woodpeckersin that it con- sists of a small anterior superficial portion and a larger posterior deep portion. Origin of the anterior superficial portion usually is from part or all of the last two cervical spinous processes,and insertion is on the dorsal margin of the scapular blade near the bend (Figure 3). In Jynx it has a much broader insertionand is not easily separated from the posterior deep portion. In piculets the origin of the 68 Wx•r•M R. GOODGE [Auk, Vol. 89 Dolt. mai. Hurt dor. ant, TrJ. post. Rhomb.prof. Figure 1. Phloeoceastesleucopogon. Dorsal view of left shoulder region. Deltoideus major has been reflected to show insertions of latissimus dorsi. posterior deep portion is fleshy from the ilium in addition to that from the thoracic spinousprocesses. Serratus pro/undus.---Area of origin of this muscle has been reduced as only Jynx has an origin from the last cervical rib; in others it is from two to four cervical transverse processesonly. In Dryocopus, Mulleripicus, melanerpines,Sphyrapicus, Dendrocopos scalaris, D. albolarvatus, Xiphidiopicus, Chrysocolaptes, and Phloeo- ceastesorigin includes the next to the last cervical vertebra. In others it is from two or three more anterior (Figure 2). Serratus anterior.--Origin in most woodpeckersis from the last cervical rib (Figure 2), but in a few including Jynx, Nesoctites, Sasia, Campethera, Micropternus, Dinopium, Melanerpes /ormicivorus, Centurus pucherani, Xiphidiopicus, and Thripias it is also from the first thoracic rib, and in Pic•mnus and Mesopicosfrom the first thoracic only. Origin from two ribs is usual in passerinesand other birds. Origin from only one