Geothelphusa makatao sp. nov. (Crustacea: Brachyura: Potamidae), a new freshwater crab from an uplifted Pleistocene reef in Taiwan

Abstract

A new species of potamid freshwater crab, Geothelphusa makatao, is described from southwestern Taiwan, based on morphological characters and mitochondrial DNA evidence. The new species differs from close congeners, G. pingtung Tan & Liu, 1998, G. shernshan Chen, Cheng & Shy, 2005, and G. ancylophallus Shy, Ng & Yu, 1994 and a superficially similar species, G. albogilva Shy, Ng & Yu, 1994, in the structure of its ambulatory legs, thoracic sternum, male abdomen, and male first pleopods. The unique gene sequences of 16S rRNA and cytochrome oxidase I also support the recognition of this coastal population, which is isolated from other closely related species inhabiting montane areas. Except for G. makatao, the phylogenetic analysis showed that there are three additional hill subclades within the G. pingtung clade, G. shernshan, G. pingtung and the Liangshan subclade, situated in different watersheds of rivers or streams near the Central Range in the southwestern Taiwan.

Out of Borneo: Neogene diversification of Sundaic freshwater crabs (Crustacea: Brachyura: Gecarcinucidae: Parathelphusa)

“…As overlapping ranges between species are rare, we can attribute the philopatry of freshwater crabs to enclosed drainage systems, as shown previously (e.g. Daniels, ; Shih et al ., ; Jesse et al ., , ). Thus, in freshwater crabs allopatry is an important factor in the evolution and maintenance of species boundaries.…”

“…Ng, ; Ng & Chia, ; Cumberlidge & Ng, ), and freshwater crab distributions in general have been shown to reflect palaeogeography (e.g. Daniels et al ., ; Shih et al ., ; Klaus et al ., ; Jesse et al ., ). Two families of primary freshwater crabs occur in Southeast Asia: the Potamidae and the Gecarcinucidae.…”

“…However, this dramatic drop in diversification rate has to be treated with caution, as this phenomenon may be an artefact caused by sampling error (because younger lineages are more prone to escape sampling, see Nee et al, 1994;Revell et al, 2005), or by the existence of cryptic species, which is not uncommon in freshwater crabs (e.g. Shih et al, 2008;Shih & Shy, 2009;Jesse et al, 2010;Daniels, 2011).…”

Genetic evidence for the recognition of two fiddler crabs, Uca iranica and U. albimana (Crustacea: Brachyura: Ocypodidae), from the northwestern Indian Ocean, with notes on the U. lactea species-complex

“…Mitochondrial markers, large subunit (16S) ribosomal (r)RNA and cytochrome oxidase I (COI), have proven to be useful markers for suggesting species boundaries and phylogeny of crabs and shrimps (e.g., Schubart et al, 2000;Chu et al, 2003;Shih et al, 2004Shih et al, , 2006Shih & Cai, 2007;Shih & Suzuki, 2008;Shih & Shy, 2009). However for Uca, the only attempt at a genetically based phylogeny has been the joint study using 16S rRNA reported by Levinton et al (1996) and Sturmbauer et al (1996).…”

Molecular evidence and differences in gonopod morphology lead to the recognition of a new species of the freshwater crab genus Candidiopotamon Bott, 1967 (Crustacea, Brachyura, Potamidae) from eastern Taiwan

“…In the case of Geothelphusa , nearly 40 species have been described from Taiwan, many of them recently ( Shih and Ng 2011 ; Shy et al 2014 , 2020 , 2021 ), and new species descriptions are still underway (cf. Shy et al 2020 ), although a few of them have been synonymized ( Shih and Shy 2009 ; Shih and Ng 2011 ; Shy et al 2020 , 2021 ) or at least suggested to be conspecific ( Shih et al 2023 ). In contrast, Candidiopotamon has only one described species in Taiwan, i.e., Candidiopotamon rathbuni (De Man, 1914), occurring throughout the island.…”