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A.P. RUSSELL AND A.M. BAUER 



and Russell 1980) and Eurydactylodes (Bohme and Sering 1997). 

 Although the secretion has not been characterised, it is likely similar 

 to that of Strophurus spp., which is proteinaceous (Rosenberg etal. 

 1984) and is effective in detering at least some small predators, such 

 as spiders, which become entangled in the secretion (Minton 1982). 

 However, both the anatomy of the gland and the ejection mechanism 

 of secretion differ between the two gecko genera, suggesting that the 

 apparatus in convergent (Bohme and Sering 1997). Eurydactylodes 

 is also convergent with Strophurus in its bright yellow-orange 

 mouth coloration. Most geckos have unpigmented buccal linings. 



Eurydactylodes also shares some features with gekkonid geckos. 

 Most notable is the presence of extracranial endolymphatic sacs in 

 the neck region, especially in juveniles and reproductive females. 

 These calcium-storing structures frequently form conspicuous bulges 

 on the necks of gekkonids, but in diplodactylids are intracranial and 

 contain little calcium. Eurydactylodes is an exception in that very 

 large sacs are often present, in some individuals artificially increas- 

 ing the apparent size of the head (Bauer 1989). Perhaps related to 

 this, the eggshells of Eurydactylodes, although similar in most 

 regards to those of typical carphodactylines, are covered by a 

 calcified outer surface (Bauer and Sadlier 2000), which otherwise 

 typifies gekkonids (Bustard, 1968; Werner, 1972). 



Gekkoninae 



The Gekkoninae was the most heterogeneous and unwieldy of 

 Underwood's higher order groups and it has remained largely 

 intractable to this day. Indeed, as a result of the resolution of the 

 content of the Diplodactyinae, the Gekkoninae has grown signifi- 

 cantly. Further, the vast majority of all new or resurrected genera 

 since 1954 are gekkonines. Underwood (1954) initiated the process 

 of dismantling some of the larger gekkonid genera that he recog- 

 nised as polyphyletic assemblages of digitally convergent taxa. In 

 particular he addressed the composition of Phyllodactylus and 

 Gymnodactylus, two of the largest and most cosmopolitan taxa. 



Subsequent reduction of Phyllodactylus occurred with the removal 

 of Crenadactylus and its shift to the Diplodactylinae (Dixon and 

 Kluge 1964), and the placement of several geographically coherent 

 gekkonine leaf-toed forms into Paroedura (Dixon and Kroll 1974). 

 Asaccus (Dixon and Anderson 1973), Urocotyledon (Kluge 1983), 

 and Christinus (Wells and Wellington 1983). All remaining Old 

 World leaf-toed geckos were removed from the now strictly American 

 Phyllodactylus by Bauer et al. (1997), who erected Haemodracon, 

 Dixonius, Afrogecko, Cryptactites and Goggia, and resurrected 

 Euleptes. Nussbaum et al. (1998) further provided a new generic 

 name for the elongate-bodied leaf-toed geckos of Madagascar, 

 Matoatoa. Arnold and Gardner (1994) also provided a species level 

 phylogeny for Asaccus, using a variety of Old and New World leaf- 

 toed geckos as outgroup taxa, but without explicit justification. Both 

 these authors and Nussbaum et al. (1998) suggested that at least 

 some phyllodactyl taxa might be closely related. 



A similar dismantling of Gymnodactylus was begun by Underwood 

 (1954), who removed Phyllurus to the Diplodactylinae and recog- 

 nised the genera Gymnodactylus, Cyrtodactylus and Wallsaurus for 

 a subset of the naked-toed geckos. Subsequently Golubev and 

 Szczerbak (1981) and Szczerbak and Golubev (1984) divided the 

 Old World forms placed by Underwood in Cyrtodactylus, which 

 they regarded as polyphyletic, into several genera, including the 

 Palearctic Tenuidactylus, Cyrtopodion, Mesodactylus, Carinato- 

 gecko, Mediodactylus and Asiocolotes. Tropical forms were divided 

 into Cyrtodactylus, Geckoella and Nactus (Kluge 1983). 



The effect of these actions has been to dismantle several larger, 

 clearly polyphyletic groups and to instead recognise a larger number 



of smaller, but putatively monophyletic, genera. The problem re- 

 mains, however, that relationships among these genera are poorly 

 resolved. While the identification of monophyletic units is a neces- 

 sary first step in the resolution of gekkotan relationships, the increase 

 in the number of such units increases the sampling required in order 

 to erect a hypothesis of relationship across all members of the group. 

 This has been the major stumbling block in the phylogenetic inter- 

 pretation of the Gekkoninae: any attempt to resolve relationships 

 among some subset of genera of necessity requires an analysis of 

 virtually all other genera. The sheer diversity of the group has been 

 an impediment to its resolution. 



Despite the difficulty of determining relationships among 

 gekkonines, some clusters of genera that appear to be monophyletic 

 have been identified. These groups are chiefly those that share 

 highly distinctive and generally restricted derived conditions. Thus, 

 such groups have typically been identified on the basis of informa- 

 tion intrinsic to themselves rather than on the basis of outgroup 

 comparison. Indeed, when outgroup analysis has been attempted, 

 the choice of outgroup has been based on geography (e.g., Joger 

 1985; Bauer 1990b; Abdala 1996; Macey et al. 2000) or on some 

 preconceived notion of similarity, usually based on digital anatomy 

 (e.g., Arnold and Gardner 1994; Macey et al. 2000). Chromosomal 

 characteristics of gekkonids are highly heterogeneous (King 1987c), 

 but such variation may occur within genera and thus has contributed 

 little to the resolution of higher order relationships. 



One of the most substantially supported subgroups of gekkonines 

 is the Pachydacnlus group. This is a cluster of genera sharing the 

 unique feature of hyperphalangy of digit I of both the manus and pes. 

 The group includes the chiefly Mediterranean genera Tarentola and 

 Geckonia and the southern Africa forms Pachydactylus, Rhoptropus, 

 Chondrodactylus, Colopus, and Palmatogecko. Underwood (1954) 

 recognised the relationship of all of these except Pachydactylus 

 itself, placing them in the Diplodactylinae and identifying a peculiar 

 pupil shape, the Rhoptropus-type, that all shared. Several species of 

 Pachydactylus (e.g., P. austeni, P. kochi) are strikingly similar, even 

 in external appearance, to Colopus and Palmatogecko. By chance, 

 however. Underwood's (1954) list of taxa examined reveals that he 

 did not examine any of these species. Hyperphalangy had previ- 

 ously been identified in some members of the group by Wellborn 

 (1933), but her sampling was inadequate to highlight the potential 

 phylogenetic value of the feature. Russell (1972, 1976) and Haacke 

 (1976) recognised the significance of hyperphalangy and argued 

 convincingly that this was evidence of the relatedness of these taxa. 

 Virtually all subsequent workers (Bauer 1990b, 2000; Kluge and 

 Nussbaum 1995; Lamb and Bauer 2002; but see Joger 1985) have 

 agreed that these seven genera (including collectively approxi- 

 mately 80 species) form a monophyletic group. With closely related 

 taxa thus identified, species level phylogenies have been possible 

 within constituent genera (e.g., Rhoptropus: Bauer and Good 1996, 

 Lamb and Bauer 2001; Pachydactylus: Lamb and Bauer 2000, 

 2002). 



Other clusterings, although less well investigated, have also been 

 proposed, although not necessarily tested. The Gekko group, con- 

 sisting of Gekko, Gehyra, Hemiphyllodactylus, Eepidodactylus, 

 Luperosaurus, Perochirus, Pseudogekko, and Ptychozoon, all share 

 similarities of digital structure (Kluge 1968; Russell 1972, 1976) 

 and are probably a monophyletic group, although particular patterns 

 of intergeneric relationship remain untested. 



The large and heterogeneous genus Hemidactylus seems to be 

 related to a number of much smaller genera that are also similar 

 digitally, and are united by synapomorphies of size and shape of the 

 intermediate phalanges (Russell, 1977a). Dravidogecko, for example, 

 has been synonymized with Hemidactylus on the basis of digital 





