Saturday, February 18, 2023

[Herpetology • 2023] Hyperolius ukaguruensis • Diversification of Spiny-throated Reed Frogs (Anura: Hyperoliidae) with the Description of A New, Range-restricted Species from the Ukaguru Mountains, Tanzania

Hyperolius ukaguruensis 
 Lawson, Loader, Lyakurwa & Liedtke, 2023 

The spiny-throated reed frog species group is a small radiation of Hyperolius frogs from East Africa. Unlike many members of the genus which have relatively wide distributions, these species tend to be small-range endemics found in montane and submontane forests. Recent discovery of a golden-hued frog with the clade-specific traits of spines on their gular discs prompted a morphological and genetic exploration of the distinctness of this new lineage and relationships to other members of the clade. Genetic (mitochondrial and nuclear loci) results resolved many sister-relationships, but deeper nodes in the phylogeny were poorly resolved. A reduced-representation genome-wide Single Nucleotide Polymorphism (SNP) dataset was able to fully resolve the phylogenetic relationships within this clade, placing this new lineage, here named after the mountain range in which is it found–Hyperolius ukaguruensis sp. nov., as an early diverging lineage within the group. This new species is distinct from all other spiny-throated reed frogs, necessitating further understanding as a single-mountain endemics vulnerable to habitat loss and potential decline. Morphometric analyses identify clear morphological characteristics that are distinct for the herein described species, most noticeably in that the eyes are significantly smaller than other members of the genus for which we have samples.

Photos in life of Hyperolius ukaguruensis sp. nov.
 A,B) Male (BMNH 2022.7682; holotype) and female (BMNH 2022.7683; paratype) in vivo,
C) H. ukaguruensis sp. nov. male and female in axillary amplexus, and D) Type locality habitat.
Photos by C. Liedtke. 

Hyperolius ukaguruensis sp. nov.
Diagnosis.— Horizontal pupil with distinctive gular flap in males. As with most other members of the spiny-throated group (H. spinigularis, H. burgessi, H. davenporti, H. minutissimus, H. ruvuensis, H. ukwiva), H. ukaguruensis sp. nov. also has the presence of dermal asperities (including the body and chin region) on the ventrum. This trait is unique amongst members of the genus Hyperolius. The presence of asperities on the gular flap diagnoses H. ukaguruensis sp. nov. from H. tanneri, for which they are absent. Hyperolius ukaguruensis sp. nov. primarily has asperities anteriorly positioned (closer to the mouth), which differentiates it from H. spinigularis, H. burgessi and H. davenporti which have an even distribution of dermal asperities on the gular flap. Hyperolius minutissimus and H. ukwiva have a similar distribution of asperities to H. ukaguruensis sp. nov.. Furthermore, in males, H. ukaguruensis sp. nov has a distinctively shaped gular flap, differentiating it from H. davenporti, H. tanneri and H. burgessi (Figs 4 & 5). Quantification of differences in gular shape from the H. ukwiva were not possible due to inability to locate the only known male specimen, but should be investigated in future studies.

Etymology.— Hyperolius ukaguruensis sp. nov. is named after the forested mountain block (Ukaguru Mountains) where the type series was collected. The species name is a masculine Latin singular adjective in the nominative case.

 Lucinda P. Lawson, Simon P. Loader, John V. Lyakurwa and H. Christoph Liedtke. 2023. Diversification of Spiny-throated Reed Frogs (Anura: Hyperoliidae) with the Description of A New, Range-restricted Species from the Ukaguru Mountains, Tanzania.  PLoS ONE. 18(2): e0277535.  DOI: 10.1371/journal.pone.0277535