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| A. Duttaphrynus brevirostris (BNHS 6126) from Kempholey Ghat region in Sakleshpur taluk. B. Duttaphrynus peninsularis (SDBDU 6370) from Wattakolli. C–D. Duttaphrynus stomaticus: C. SDBDU 2015.2909 from Assam; D. SDBDU 2012.2170 from Rajasthan. in Bisht, Garg, ... et , 2021. DOI: 10.3897/zse.97.61770 |
Abstract
We rediscovered two species of toads, Bufo stomaticus peninsularis and Bufo brevirostris, which were described from Peninsular India 84 and 101 years ago, respectively, but have not been reported since. Because the name-bearing types of both species are either damaged or lost, we provide detailed redescriptions, morphological comparisons, and insights into phylogenetic relationships with closely related members of the genus Duttaphrynus sensu lato, based on new material from the type locality of each species. We clarify and validate the identity of D. brevirostris, which was rediscovered from multiple localities in the Malenadu and adjoining coastal regions of Karnataka. We also demonstrate that Bufo stomaticus peninsularis, which was considered a synonym of Duttaphrynus scaber, is a distinct species. Bufo stomaticus peninsularis differs from Duttaphrynus scaber morphologically and genetically, and is more closely related to members of the Duttaphrynus stomaticus group. We also clarify the identity of the namesake species of the Duttaphrynus stomaticus group, which is reported widely in India and neighbouring countries, but lacks sufficient taxonomic information due to its brief original description and reportedly untraceable type material. We located and studied the complete syntype series of D. stomaticus, probably for the first time in over a century, and we report on the status of available specimens, provide detailed description of a potential type, compare it to related species, and clarify the species’ geographical range. Our molecular analyses suggest that D. stomaticus is minimally divergent from, and possibly conspecific with, D. olivaceus. Our analyses also clarify its relationship to the closely-related D. peninsularis comb. nov., with which it was previously confused. Finally, our study provides other insights into the phylogenetic relationships and genetic differentiation among various species of Duttaphrynus toads.
Key Words: Amphibia, Bufo stomaticus peninsularis, distribution, Duttaphrynus brevirostris, Duttaphrynus stomaticus group, Firouzophrynus, molecular phylogeny, redescription, rediscovery, taxonomy
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| Topotype of Duttaphrynus brevirostris (Rao, 1937), topotype of D. peninsularis (Rao, 1920), and referred specimens of D. stomaticus (Lütken, 1864) in life. A. Duttaphrynus brevirostris (BNHS 6126) from Kempholey Ghat region in Sakleshpur taluk. B. Duttaphrynus peninsularis (SDBDU 6370) from Wattakolli. C–F. Duttaphrynus stomaticus: C. SDBDU 2015.2909 from Assam; D. SDBDU 2012.2170 from Rajasthan; E. SDBDU 2012.2172 from Delhi; and F. SDBDU 2012.2268 from Bihar. |
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| Phylogenetic relationships and genetic differentiation in the genus Duttaphrynus. A. Maximum Likelihood phylogenetic tree based on 5,737 bp DNA comprising nine mitochondrial gene regions and two nuclear genes, showing phylogenetic relationships between the major species-level lineages. Values above and below the branches indicate Bayesian Posterior Probabilities (BPP) and RAxML Bootstrap Support (BS), respectively; B. Maximum Likelihood barcoding tree based on 524 bp of the mitochondrial 16S rRNA sequences. BPP and BS support values are indicated above and below the branches, respectively. Coloured vertical bars outside the terminal node labels indicate putative species delimited in the bPTP analysis; C. Median-Joining haplotype network based on 42 haplotypes recovered from 133 sequences of the 16S gene (420 bp). Size of the coloured circles is proportional to the number of haplotypes; black circles indicate median vectors; each branch represents a single mutation step; additional mutational steps are indicated by values in parentheses; photo credits: D. crocus (Guinevere O. U. Wogan), D. olivaceus (Parham Beyhaghi), and D. dhufarensis (Todd W. Pierson). |
Duttaphrynus brevirostris (Rao, 1937)
Duttaphrynus peninsularis (Rao, 1920), comb. nov.
Duttaphrynus stomaticus (Lütken, 1864)
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| Geographical distribution of Duttaphrynus brevirostris (dark grey), D. peninsularis (blue), and D. stomaticus (orange). |
Conclusions:
The results of this study resolve long-standing uncertainty regarding the identities and taxonomic status of two toad species described from Peninsular India. Bufo brevirostris Rao, 1937 was considered a problematic taxon, because its original name-bearing types are lost. Bufo stomaticus peninsularis Rao, 1920 was long forgotten as an available name for Peninsular Indian populations closely related to Duttaphrynus stomaticus. We substantiate D. peninsularis to be a distinct species, which is both morphologically diagnosable and phylogenetically distinct. Taxonomic redefinition of both of these species was achieved not just by examining the original literature and available types, but also through an effort to rediscover new material from each species’ respective type locality. The redescription of Bufo brevirostris Rao, 1937 based on new topotypic material, along with detailed comparisons to related taxa, objectively clarifies its identification for future reference. Similarly, topotypic material for Bufo stomaticus peninsularis Rao, 1920 enabled a detailed re-evaluation of its taxonomic status in the absence of a well-preserved type. Altogether, our results emphasise that new collections from type localities of historically available names should be attempted when taxonomic resolution is not feasible on the basis of original descriptions or type specimens (Bailey 1933; Garg and Biju 2016).
The present work clarified the taxonomic identity of another species, Duttaphrynus stomaticus, which was overlooked due to its presumed wide distribution. This taxon was known only from its brief original description, and the available, original name-bearing types remained unexamined due to literature-based misconceptions concerning their untraceability (Dutta 1997; Ganesh et al. 2020). We located the well-preserved eight original type specimens, and clarified the status of name-bearing types and the identity of this species, which we redescribed to facilitate future taxonomic studies. This action also aided our objective of resolving the taxonomic status of D. peninsularis, which was originally defined as a variety of D. stomaticus. Our results have important implications concerning the taxonomy and geographical ranges of the two species. Hereafter, D. stomaticus should be considered as a species found in the northern regions of South Asia, whereas its sister taxon D. peninsularis should be recognised as a Peninsular Indian form (Fig. 4; Suppl. materal 1: Table S3). Detailed redescriptions provided in this study will enable proper identification and range delineation, and serve as the basis for future conservation action. Knowledge of phenotypic variation and phylogenetic affinities of both species will also facilitate a better understanding of patterns of genetic differentiation within the genus, particularly among the species of the Duttaphrynus stomaticus group.
Karan Bisht, Sonali Garg, A. N. D. Akalabya Sarmah, Saibal Sengupta and S. D. Biju. 2021. Lost, Forgotten, and Overlooked: Systematic Reassessment of Two lesser-known Toad Species (Anura, Bufonidae) from Peninsular India and Another Wide-ranging northern Species. Zoosystematics and Evolution. 97(2): 451-470. DOI: 10.3897/zse.97.61770
