Genetic and Morphological Studies on Goniurosaurus kuroiwae (Squamata: Eublepharidae), with a Description of a New Species from the Northern Part of Okinawajima Island, Ryukyu Archipelago, Japan

Abstract

Goniurosaurus k. kuroiwae consists of two genetically diverged entities (i.e., northern and southern lineages) that are geographically separated by a narrow hybrid zone in the north–central part of Okinawajima Island, Ryukyu Archipelago, Japan. Our molecular analyses using single nucleotide polymorphism data confirmed their remarkable genetic differentiation. Morphological comparisons using random forest models further revealed that these two lineages could be distinguished by combinations of several characteristics. Considering that these two entities have persisted within a single island, they deserve to be given full species status. The type locality of the nominal species, G. kuroiwae, fell within the range of the “southern species” and the morphological features of the holotype agreed well with the “southern species”. Hence we described the populations of the northern part of Okinawajima and Kourijima as a new species, Goniurosaurus nebulozonatus sp. nov. This new species differs from other congeners in the Ryukyus with a combination of the following character states: reddish brown iris, 4–7 postmentals, flat and imbricate ventral scales, denser tubercles on the femur, single most-enlarged scale on the pes base, mid-dorsal stripe present at the nape and absent in the posterior part of the trunk, incomplete or no nuchal loop, dorsal band on the posterior trunk present, and obscure dorsal stripes/ bands. The new species was inferred to be a sister taxon of G. kuroiwae sensu stricto, so allocating other taxa as subspecies of G. kuroiwae no longer makes sense. Thus, we propose elevating all five taxa currently regarded as subspecies of G. kuroiwae to full species, G. orientalis, G. sengokui, G. toyamai, G. yamashinae, and G. yunnu. Adding G. splendens in Tokunoshima and the two species in Okinawajima, there are now seven extant and one extinct species exist in the Ryukyu Goniurosaurus.