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A. P. RUSSELL AND A.M. BAUER 



brille and lack of moveable lids typical of other geckos. Further. 

 Walls (1942) and Prince (1949) had examined the eyes of some 

 geckos in their broader ophthamological treatments, suggesting 

 avenues for further research. 



Walls' (1942) comprehensive treatment of the vertebrate eye led 

 Underwood to hypothesise that this organ system could yield useful 

 and stable associations of characters. The general recognition of the 

 retinal characteristics of the eyes of geckos as evidence of secondary 

 nocturnality, and a preliminary survey (Underwood 1951b) of the 

 form of the pupil suggested that a more intensive survey of pupil 

 form may provide a means by which gekkonids could be subdivided 

 into more manageable and meaningful subsets reflective of their 

 evolutionary history. Underwood (1954) set himself the task of 

 surveying a moderately comprehensive collection of preserved 

 geckos at the Museum of Comparative Zoology, Harvard Univer- 

 sity, and to analyse the resulting data. He used these data to erect the 

 first modern generic level analysis of gekkotan relationships. He 

 recognised potential problems with character state interpretation 

 caused by state of preservation and the limitations of a single- 

 character classification, but nonetheless regarded pupil character 

 states to be sufficiently discrete for the purpose of establishing a 

 workable classification of geckos, which would be subject to modifi- 

 cation as additional data became available. Werner (1977) later 

 demonstrated that pupil shape and dilation change with differing 

 light levels, and these observations have helped refine Underwood's 

 (1954) initial conclusions (see below). 



UNDERWOOD'S CLASSIFICATION OF THE 

 GECKOS 



Underwood (1954) recognised three families of gekkotan lizards. 

 The Eublepharidae was characterised by true eyelids, the lack of a 

 spectacle and vertical pupils reflective of the nocturnal adaptations 

 of the family. The five genera he included were those subsequently 

 placed by Kluge ( 1967a) in his Eublepharinae, and by Kluge (1987) 

 and Grismer (1988) in the Eublepharidae. [Note: The current alloca- 

 tion of taxa employed in this article is based upon Kluge, 2001]. 

 Underwood (1954) considered Aeluroscalabotes as the most primi- 

 tive member of the family. It has subsequently been regarded as the 

 sister group of all remaining eublepharids (Grismer, 1988). 



Underwood's Sphaerodactylidae was supported by the presence 

 of a round, diurnal-type pupil (or eliptical or straight vertical pupil in 

 some cases), the existence of a fovea, and the presence of a specta- 

 cle. He included five genera therein, corresponding to Kluge's 

 (1967a) Sphaerodactylinae and later Sphaerodactylini (Kluge 1987, 

 1995). 



All remaining genera were placed in the Gekkonidae, character- 

 ised by a spectacle and lack of a fovea. Pupil shape was variable. 

 Within the Gekkonidae he recognised two subfamilies, the 

 Diplodactylinae and the Gekkoninae. The former had vertical pupils 

 with straight margins, or circular pupils. He included 22 genera in 

 this group. Among them are all of the genera now assigned to the 

 Diplodactylinae by Kluge (1967a) except for Eurydactylodes, 

 Pseudothecadactylus, and Crenadactylus. Underwood had doubts 

 about the placement of the first of these genera (see below), speci- 

 mens of which he had not examined himself, and changed its 

 allocation the following year (Underwood 1955). Crenadactylus 

 ocellatus was examined but was included with Phyllodactylus in the 

 Gekkoninae by Underwood ( 1 954). The Diplodactylinae was subse- 

 quently retained by Kluge (1987) and Bauer (1990a), although its 

 affinities with the Pygopodidae were uncertain (see below). 



Stephenson and Stephenson (1956) regarded New Zealand geckos 

 (Hoplodactylus and Naultinus) as the most primitive forms on the 

 basis of Underwood's (1955) revised view that amphicoelous verte- 

 bral centra are primitive within lizards and within the Gekkota. 

 Furthermore, Stephenson (1960) rejected Underwood's (1954) 

 ophthamalogical division of the Gekkonidae into two subfamilies as 

 it was inconsistent with osteological characters, but neither 

 Underwood nor Stephenson 'correctly' placed all Australian genera. 



Also included in Underwood's Diplodactylinae were several 

 genera not now regarded as closely allied to the Australo-Pacific 

 diplodactylines: Aristelliger, Chondrodactylus, Colopus, 

 Gymnodactylus, Palmatogecko, Phelsuma, Ptenopus, Rhoptwpella, 

 Rhoptropus, SaurodacTylus, and Teratoscincus. Four of these, 

 Chondrodactylus, Colopus, Rhoptropus, and Palmatogecko, share 

 many features in common with each other and with Pachydactylus 

 (placed by Underwood [1954] in the Gekkoninae). Kluge (1967a) 

 moved these taxa to the Gekkoninae. and Russell ( 1 972) and Haacke 

 (1976) established the affinities of these forms as part of the Pachy- 

 dactylus group (see below). 



Two other taxa, Rhoptwpella and Phelsuma, have also been 

 regarded as being closely related to one another (see below). Both of 

 these genera, as well as all remaining ones, were moved to the 

 Gekkoninae by Kluge (1967a) and have remained there since, with 

 Teratoscincus as the sister group of all other gekkonines. The 

 affinities of Gymnodactylus have remained problematic (Abdala 

 1988, 1996; Abdala and Moro 1996), as have those of Aristelliger 

 (Russell and Bauer 1993), and Ptenopus (Bauer 1990b), whereas 

 Saurodactylus has been considered allied to the sphaerodactyline 

 lineage (Kluge 1995). Underwood's Phyllurus also included within 

 it a species now assigned to the gekkonine genus Nactus. 



The Gekkoninae were characterised by Gekko-lype pupils or 

 secondarily circular pupils. Underwood's (1954) Gekkoninae, al- 

 though lacking the taxa mentioned above (and with the addition of 

 Eurydactylodes, and Crenadactylus as Phyllodactylus ocellatus) 

 otherwise included all of the genera placed in the group by Kluge 

 (1967a). This grouping also included Uroplatus, which by virtue of 

 a large suite of autapomorphic features had been accorded separate 

 familial status by many previous workers (see Bauer and Russell 

 1989 for a review). In this regard, Underwood's (1954) results were 

 similar to those of Wellborn (1933), who had based her conclusions 

 on osteological data. Underwood did not rely entirely on the pupil 

 character, however, as Lygodactylus, with round pupils, was placed 

 in the Gekkoninae on the basis of other (digital) similarities with 

 Hemidactylus. 



Nine genera were not assigned to family or subfamily by 

 Underwood. Five of these were unplaced due to lack of material. 

 The remaining four were taxa with round pupils that were regarded 

 as secondarily diurnal gekkonids, but which Underwood consid- 

 ered, on the basis of existing data, could not be allocated to one or the 

 other of his two subfamilies. Of the latter, one genus, Ancylodactylus, 

 has been synonymized with another, Cnemaspis. The other two were 

 Quedenfeldtia and Pristurus. Of the genera not examined. 

 Ceramodactylus has since been subsumed in Stenodactylus, and 

 Dravidogecko has been synonymized with Hemidactylus. 



Underwood also recognised some instances of convergence among 

 geckos. Specifically he addressed the allocation of species of leaf- 

 toed geckos (then chiefly distributed in Diplodactylus and 

 Phyllodactylus), and bent-toed geckos (then mostly placed in 

 Gymnodactylus). Among the leaf-toed geckos, pupil shape sug- 

 gested the transfer of several species of African Diplodactylus to 

 Phyllodactylus. These geckos are now regarded as members of the 

 genus Urocotyledon (Kluge, 1 983) and are, as Underwood indicated, 

 correctly assigned to the Gekkonidae rather than the Diplodactylidae. 





