Integrating phylogenetics, morphology, and osteology to delimit a new species of endemic montane sheep frog (Microhylidae: Hypopachus) from the Lenca Highlands of Honduras

Abstract

Due to their conserved morphology, cryptic species have long been problematic for taxonomists. When attempting to assess diversity and delimit species within these taxa, it has been recognized that an integrative approach can be very useful, whereby independent, yet complementary lines of evidence are utilized. New World microhylids (Anura: Microhylidae: Gastrophryninae) of the genera Gastrophryne and Hypopachus have been highly confounding to taxonomists, due to their extreme morphological conservatism, as well as their fossorial nature resulting in a lack of specimens and public genetic information. Currently, two microhylid species are recognized in Honduras: H. barberi and H. variolosus. Here, we integrate three independent lines of evidence (morphology, osteology, and genetics) to examine previously undescribed diversity among populations of H. barberi in the Lenca Highlands of south-western Honduras. Mitochondrial and nuclear DNA identify populations from the Lenca Highlands as being distinct from other populations previously allocated to H. barberi. This distinction is further supported by divergence dating estimates that place the split between these populations and others of H. barberi in the late-Miocene. We also find several significant morphological and osteological differences between H. barberi and Lenca Highlands populations, including extensively reduced ossification in the (especially cranial) skeleton of the Lenca Highland populations. As a result of these distinctions, we formally describe the Lenca sheep frog as a new species, Hypopachus guancasco sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:pub:2B2B4942-2925-42C8-8329-431F55B41AA3

Key words:

• Amphibia
• cryptic species
• Honduras
• integrative taxonomy
• Lenca Highlands
• microCT
• species delimitation

Acknowledgements

Research was carried out under permits issued by Instituto Nacional de Conservación y Desarrollo Forestal, Áreas Protegidas y Vida Silvestre (ICF; Resolución DE-MP-086-2010, Resolución DE-MP-095-2014, Dictamen DVS-ICF-045-2010, and Dictamen DVS-112-2014). Fieldwork and all work with animal subjects was carried out under IACUC #04-1314. We are indebted to the following individuals and organizations for supporting our work in Refugio de Vida Silvestre Texíguat: A. J. Fuentes (PROLANSATE); A. A. Pagoada-Saybe (Municipalidad de Arizona), S. Laínez, I. Acosta, R. Downing, A. Alegría (ICF); guardabosques E. Aguilar (San José de Texíguat), A. Contreras (Mezapita), and A. Portillo (Jilamito Nuevo); and J. Dubón, majordomo at La Liberación. We thank B. K. Atkinson, C. A. Cerrato, L. N. Gray, L. A. Herrera, E. Hofmann, P. House, M. M. Mejía, C. Navarro-Umaña, V. Strange A. L. Stubbs, H. Vega-Rodríguez, K. Weinfurther for their valued assistance and hard work in the field during 2010, 2015, and 2016. A. Driskell and D. Mulcahy (Smithsonian Institution Laboratory of Analytical Biology) contributed the raw 16S sequence data, in collaboration with R. McDiarmid (USNM) as part of the 'Barcoding the Herpetofauna of Eastern Nuclear Central America' project. We thank R. McDiarmid, J. Jacobs, S. Gotte, and J. Poindexter (USNM), C. Sheehy (FLMNH), and J. Sheridan and S. Kennedy-Gold (CM) for facilitating and preparing the loans of comparative materials and accessioning the type series. We thank R. O. de Sá, J. A. Campbell, and E. N. Smith for grants of tissues from their respective collections, and K. Row for lending us his high-resolution camera for taking specimen images. J. Hargrove and L. Fucsko provided helpful comments on a draft of this manuscript. We are grateful to K. M. Rogers for providing the hand and foot illustrations. Finally, we would like to thank Eli Greenbaum, Gunther Köhler, and David Gower who provided extensive and valuable feedback on this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data accessibility

All sequences were deposited in NCBI GenBank (accession numbers are included in Supplementary Table S1). We have included a data package on Dryad (https://doi.org/10.5061/dryad.g79cnp5n5) that includes sequence alignments for all three datasets (mtDNA only, nuDNA only, and mt + nuDNA), the input file for BEAST for divergence dating, and the raw morphological measurements. CTscans are available on MorphoSource at https://www.morphosource.org/Detail/ProjectDetail/Show/project_id/P1031 (UTA A-7565: doi:10.17602/M2/M115984; UTA A-7559: doi:10.17602/M2/M115985; UF 166707: doi:10.17602/M2/M115986; UF 157250: doi:10.17602/M2/M115987).

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2020.1841325

Associate Editor: David Gower

Additional information

Funding

This work was supported by the Critical Ecosystem Partnership Fund, Indiana University of Pennsylvania (IUP) School of Graduate Studies and Research, and the National Science Foundation DEB-0949359 (to Kirsten E. Nicholson, Central Michigan University).