Israel Journal of Ecology & Evolution, 2020 http://dx.doi.org/10.1163/22244662-bja10003 Gecko diversity: a history of global discovery Peter Uetza,*, Alex Slavenkob,c, Shai Meiric,d and Matthew Heinickee,* aCenter for Biological Data Science, Virginia Commonwealth University, 1000 W Cary St, Richmond, VA 23284, USA bDepartment of Animal and Plant Sciences, University of Shefeld, Shefeld S10 2TN, UK cSchool of Zoology, Tel Aviv University, 6997801, Tel-Aviv, Israel dThe Steinhardt Museum of Natural History, Tel Aviv University, 6997801, Tel-Aviv, Israel eDepartment of Natural Sciences, University of Michigan-Dearborn,4901 Evergreen Rd., Dearborn, MI 48128, USA Abstract 1935 gecko species (and 224 subspecies) were known in December 2019 in seven families and 124 genera. These nearly 2000 species were described by ~950 individuals of whom more than 100 described more than 10 gecko species each. Most gecko species were discovered during the past 40 years. The primary type specimens of all currently recognized geckos (including subspecies) are distributed over 161 collections worldwide, with 20 collections having about two thirds of all primary types. The primary type specimens of about 40 gecko taxa have been lost or unknown. The phylogeny of geckos is well studied, with DNA sequences being available for ~76% of all geckos (compared to ~63% in other reptiles) and morphological characters now being collected in databases. Geographically, geckos occur on fve continents and many islands but are most species-rich in Australasia (which also houses the greatest diversity of family-level taxa), Southeast Asia, Africa, Madagascar, and the West Indies. Among countries, Australia has the highest number of geckos (241 species), with India, Madagascar, and Malaysia being the only other countries with more than 100 described species each. As expected, when correcting for land area, countries outside the tropics have fewer geckos. Keywords Carphodactylidae; Diplodactylidae; Eublepharidae; Gekkonidae; Gekkota; Phyllodactylidae; Pygopodidae; Sphaerodactylidae Introduction is obviously not true for human commensals such as some Geckos (Sauria: Gekkota; 1935 species) are one of three Hemidactylus or conspicuous day geckos such as Lygo- mega-diverse lineages of squamate reptiles (lizards, dactylus or Phelsuma. Nevertheless, many geckos were snakes, and amphisbaenians), along with the 1685 species described early in the history of herpetology. We fnally of skinks and 1965 species of colubrid snakes (Uetz et al. discuss the factors for species discovery and diversity and 2019), that are known today as result of the major squamate how it relates to gecko biology. radiations that began diversifying about 200 million years ago. All gecko families are relatively old compared to ei- ther skinks or colubrids. Molecular clock estimates place A history of gecko discovery the origins of gecko families deep in the Mesozoic (Gamble Only three geckos were described by Linnaeus (1758) — et al. 2008a, b, 2011; Hedges et al. 2015; Zheng and Wiens the Tokay gecko (Lacerta Gecko to Linnaeus, now Gekko 2016), and stem gekkotan fossils dating from the late Juras- gecko), Mediterranean house gecko (as Lacerta turcica, sic and Cretaceous have been recovered from multiple dis- now Hemidactylus turcicus), and Moorish gecko (Lacerta tant localities in Eurasia (Daza et al. 2014, 2016; Gauthier mauritanica, now Tarentola mauritanica). It then took her- et al. 2012; Simões et al. 2017). Not all gecko lineages have petologists 227 years, from 1758 to 1984, to describe the diversifed at the same rate. For example, there are 38 spe- frst 1000 gecko species. It has taken only 35 to describe cies of Eublepharidae, compared to 1632 species in their the next 921 (not counting subspecies). Early descrip- sister lineage (Gekkonidae + Phyllodactylidae + Sphaero- tions of gecko species commonly appeared in regional dactylidae). Thus, the high species richness of geckos has monographs or travelogues (e.g. Spix 1825) or else more been produced largely by diversifcation of a subset of suc- general zoological works (e.g. Daudin 1802). Some also cessful lineages. appeared as stand-alone contributions to journals or soci- Here we focus on the history of discovery and descrip- ety proceedings (e.g. Sparrman 1778). Early descriptions tion of gecko species. In addition, we review the diversity peaked in the mid-19th century with 19 species described of geckos in terms of species numbers, both taxonomi- in each of 1836, 1845, 1870, and 1885 (Fig. 1). These num- cally and geographically, but also in terms of discovery. bers were driven by the monumental works of André M.C. As mostly small and nocturnal species (Meiri 2020, this Duméril and Gabriel Bibron (Duméril and Bibron 1836), volume), many geckos are easy to overlook, though this John E. Gray (Gray 1845), Richard H. Beddome (Beddome *Corresponding authors. E-mails: [email protected] / [email protected] © Koninklijke Brill NV, Leiden 2020 <UN> 2 P. Uetz et al. Figure 1. Gecko species described per year 1758–2019. Some prolifc gecko describers from the 19th century are highlighted. The number of new species descriptions has surged in the past 15 years, supported by widely accessible molecular techniques and other advances. 1870a, b) and George A. Boulenger (Boulenger 1885) that Table 1. Top-11 authors who described the most gecko species were published in those years. These annual totals were still recognized as valid (i.e. 40 or more). only exceeded a century later with 24 species described in Author Species 1978. Even though 19th century authors have described most geckos in single publications, only Gray and Boulenger are Aaron M. Bauer 143 L. Lee Grismer 132 among the 10 most prolifc gecko describers (Table 1). In th Perry L. Wood 98 the late 20 century molecular methods such as karyotyp- George A. Boulenger 77 ing (e.g. Murphy 1974; King 1982) and allozyme electro- Evan S. H. Quah 63 phoresis (e.g. Branch et al. 1995) began to be employed Olivier S. G. Pauwels 54 to aid in new species discovery. Discoveries skyrocketed John E. Gray 49 st Montri Sumontha 45 in the 21 century (Meiri 2016; Uetz and Stylianou 2018) Thomas Ziegler 44 with the advent of new technologies, such as the internet, Paul Doughty 40 DNA sequencing, digital photography, and cheaper travel Paul M. Oliver 40 permitting access to remote areas, as well as the ability for individual researchers to study collections at distant species discovery such as feldwork, morphological work, museums. Nevertheless, even in modern times, gecko dis- molecular work, specimen comparisons, statistical analy- covery has been driven by relatively few individuals. Thus, sis, and literature review. In some cases this may result the 1935 gekkotans described since 1758 were authored by in species descriptions with many authors. For instance, about 950 individuals (Uetz and Stylianou 2018), of whom several gecko species have been described with more than about 100 described more than 10 gecko species each. a dozen authors, such as Cyrtodactylus phuocbinhensis Eight of the ten most prolifc describers of new species are Nguyen et al. 2013, Cyrtodactylus taynguyenensis Nguyen currently active herpetologists, with two (Aaron M. Bauer et al. 2013, Cyrtodactylus puhuensis Nguyen et al. 2014, and L. Lee Grismer) describing more than 130 species each and Cnemaspis bidongensis Grismer et al. 2014, each with (Table 1). 14 authors. None of these approach the reptile species with From the 18th through 20th centuries, most gecko spe- the highest number of authors though, which is the leio- cies were described by one or two authors. The earliest saurid Enyalius capetinga Breitman et al. 2018, with 27 au- gecko species description with more than two authors ap- thors. Many of the most prolifc gecko describers (Table 1) peared in 1970 (Minton et al. 1970). Team taxonomy has have worked together, thus, for example, almost all the de- become the norm in the 21st century, as diferent scientists scriptions by Perry Wood and Evan Quah were co-authored are often needed to carry out distinct tasks in the process of by Lee Grismer. <UN> Israel Journal of Ecology & Evolution 3 Type specimens of geckos Table 2. The top-10 collections that hold the most gekkotan pri- The primary types of the ~2000 species of geckos are kept mary types (species and subspecies). For additional type infor- in 161 collections worldwide, with 20 collections having mation see Uetz et al. (2019). about two thirds of all types (see also Uetz et al. 2019, Collection Taxa with types Table 2, Fig. 2). This is important for researchers who de- scribe new species and need to compare them to the types BMNH (London, UK) 285 MCZ (Cambridge, USA) 130 of previously described ones. By far the most gecko pri- MNHN-RA (Paris, France) 107 mary type specimens are held at the Natural History Mu- WAM (Perth, Australia) 100 seum, London (BMNH; types of 285 taxa). Among its USNM (Washington, DC, USA) 68 collections are most of the types of species described by CAS (San Francisco, USA) 69 Gray, Boulenger, and Beddome in their major 19th century SMF (Frankfurt, Germany) 68 ZMB (Berlin, Germany) 57 works, along with many types designated by Nicolas Ar- ZFMK (Bonn, Germany) 55 nold, Albert Günther, Hampton Wildman Parker, Malcolm DNMNH (Pretoria, South Africa) 52 Smith, and others, and its type specimens originate from across the globe. The Muséum National d'Histoire Na- turelle, Paris (MNHN) has a similar global scope and many primary types held at these two institutions originate from types dating from the 19th century work of Duméril and their respective continents. Fifty one institutions have only Bibron with more recent types, e.g. designated by Aaron a single primary gecko type specimen and 21 have two. Bauer and Georges Pasteur, among others. Major collec- The VertNet database (Constable et al. 2010) is the larg- tions often have geographic foci that refect the work of est meta-database of vertebrate collections, and returned scientists afliated with these institutions.