Hemidactylus subtriedrus Jerdon, 1853

Mahony, Stephen, 2011, Taxonomic revision of Hemidactylus brookii Gray: a re-examination of the type series and some Asian synonyms, and a discussion of the obscure species Hemidactylus subtriedrus Jerdon (Reptilia: Gekkonidae), Zootaxa 3042, pp. 37-67 : 60-61

What is Hemidactylus subtriedrus Jerdon, 1853 ?

Hemidactylus subtriedrus was described as a questionable new species or “variety” of H. triedrus from Nellore District (now Amamrajeevi Potti Sri Ramulu Nellore District, Andhra Pradesh), based primarily on the knowledge of the local Yanadees people who considered the two species as distinct ( Jerdon 1853). The characters described to distinguish it from the nominate form were vague except that there were fewer dark bands on the body of H. subtriedrus . Other differences such as fewer white tubercles, smaller trihedral scales and paler colour, are variations that can be commonly seen within several populations currently referred to H. triedrus . Apparently only Jerdon examined the type specimens. Stoliczka (1871, 1872) discussed specimens identified as H. subtriedrus , collected by Blanford in 1871 from near Ellore ( Blanford 1879). Annandale (1905b) examined one of the specimens discussed by Stoliczka (1872) and regarded it morphologically intermediate between H. subtriedrus and H. triedrus , but considered it as conspecific with H. triedrus and further questioned the validity of H. subtriedrus . Annandale’s (1905b) list of Indian gekkonids marks H. subtriedrus as a species not represented in the ZSI collection, indicating that the type specimens were already lost by 1905. Theobald (1876) provides two accounts of the species, first within the section dealing with Hemidactylus where he briefly summarised the diagnosis of Jerdon (1853) ( Theobald 1876:75, as H. sub-triedrus). Then, within the section dealing with Gymnodactylus as H. subtriedrus , he provides another description to include scale counts and colouration of specimens, which could correspond with H. triedrus ( Theobald 1876:85–– ibidem.:237, indexed as Gymnodactylus subtriedrus ). This error is corrected in the Errata et addenda ( Theobald 1876:ix) where the second account (on pg. 85) is suggested to be removed, but not incorporated into the earlier description (on pg. 75). Boulenger (1885) further complicated the taxonomy of H. subtriedrus . He gave, for the first time, lamellae and labial scale counts, which he considered to differentiate H. subtriedrus from H. triedrus . These characters were obtained from a single subadult female specimen also collected by Blanford, from Khammam District, northern Andhra Pradesh, approx. 370 km north of the type locality. He also erroneously gave the type locality as Ellore. Boulenger (1890), repeated these characters but omitted the Khammam locality from the distribution, mentioning only Nellore and Ellore. Smith (1935) repeated the diagnosis provided by Boulenger (1885), which subsequently formed the basis of all future identifications of H. subtriedrus in literature. Of the above mentioned authors, Stoliczka (1871, 1872), Theobald (1876), Annandale (1905b) and Smith (1935) all doubted the validity of H. subtriedrus based on specimens from Nellore, and/or Ellore.

This species has began appearing in publications with new localities only recently, however, these studies did not have specimens from the type locality or nearby, instead they relied on the diagnosis of H. subtriedrus provided in Smith (1935), not Jerdon (1853), for identifying their specimens. Mahony (2009a:34) identified, without discussion, the voucher specimen ZSI 24151 as Hemidactylus cf. maculatus , previously reported as H. subtriedrus by Sanyal and Dasgupta (1990), and later cited by Chandra and Gajbe (2005). Javed et al. (2011) concurs with the aforementioned correction along with a detailed description of the eastern H. maculatus morphotype, and corrects other misidentifications from northern Andhra Pradesh and Chhattisgarh ( Javed et al. 2009). I have examined all specimens labeled as H. subtriedrus in the ZSI and BMNH, except the Ellore specimen ( Stoliczka 1871, 1872; Blanford 1879; Annandale, 1905b). If it still exists, it is likely mixed in the general collection of H. triedrus , and attempts should be made to source it by future revisers. The specimen described by Boulenger (1885, 1890) from Khammam District, northern Andhra Pradesh (BMNH [18]74.11.11.1) and a specimen apparently not referred in literature from Ganjam District, central Orissa (ZSI 25780) also appear to be referable to H. cf. maculatus as defined by Javed et al. (2011). Bauer et al. (2010a) propose the validity of H. subtriedrus based on molecular phylogenetic divergence between captive specimens of H. subtriedrus (from India) and H. triedrus (from India and Pakistan). In light of the history of taxonomic confusion regarding H. subtriedrus , a morphological characterisation of the specimen sampled by Bauer et al. (2010a) would be necessary to verify a proposal of validity of this species.

In summary, the only reliable morphological information on the species H. subtriedrus is the original description. All additional localities and morphological information provided by subsequent authors were based on a comparison with a specimen initially described by Boulenger (1885), representing H. cf. maculatus (sensu Javed et al. 2011), or are applicable to other species. Jerdon (1853) described several characters in the original description of H. subtriedrus that differ from H. cf. maculatus (sensu Javed et al. 2011), e.g., largest adult measured by Jerdon was 6½ inches total length (= 165 mm) (vs. 259 mm), and “…number of femoral pores is the same [as H. triedrus ]”, total pores 12–28 representing the maximum range for H. triedrus populations according to Smith (1935) (vs. total pores 42–50, Javed et al. 2011). Based on these considerable differences H. subtriedrus s.s. is not conspecific with H. cf. maculatus (sensu Javed et al. 2011). The nomenclatural status of H. subtriedrus is currently unstable as the type specimens are apparently lost or originally never deposited ( Stoliczka 1872; Annandale 1905b; Das et al. 1998; pers. obs. 2007, 2009) and thus referable to a nomen dubium. The species is therefore taxonomically ambiguous and in lieu of a taxonomic review of H. triedrus , I propose that Hemidactylus subtriedrus Jerdon, 1853 be regarded as a junior subjective synonym of Hemidactylus triedrus ( Daudin, 1802) .