A new species of Himalayapotamon Pretzmann, 1966 (Crustacea: Brachyura: Potamidae) marking the westernmost distribution of the genus, with notes on its geographical range evolution

ABSTRACT

We describe a new species of freshwater crab, Himalayapotamon robertsianum sp. nov. from Punjab province of Pakistan, based on morphological characters of the carapace and the first gonopod. The new species demarcates the westernmost distribution limit of the genus. Additionally, we analysed partial sequences of the 16S rRNA locus for some species of the genus Himalayapotamon (p-distances, Bayesian phylogenetical inference), indicating that Himalayapotamon separates into an eastern and a western clade. Based on these results, we propose a biogeographical scenario that can explain the occurrence of the genera Himalayapotamon and Potamon within the same river system: we assume an ancestral widespread distribution of Himalayapotamon in the palaeo-Ganges. When drainage rearrangement diverted the western tributaries of the Ganges into the Indus since the latest Miocene, Himalayapotamon diverged into two clades. Consequently, the western clade is now sharing the Indus drainage with Potamon.

urn:lsid:zoobank.org:pub:80B52E6C-0120-4669-A6B0-9F0DA5918EE3

KEYWORDS:

• freshwater crab
• Potaminae
• taxonomy
• biogeography
• Sohan River
• vicariance

Acknowledgements

We kindly thank all persons that allowed morphological examination or extraction of tissues from material under their care and assisted during visits to their collections: Reza Naderloo (Tehran), Paul Clark (London), Peter Dworschak (Wien), and Angelika Brandt, Bianca Trautwein and the late Michael Türkay (Frankfurt). We especially thank Lukas Hartmann and Daniel Hennig (Frankfurt) for the laboratory work. We appreciated the input of two anonymous reviewers that made valuable suggestions and corrections to improve this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Geolocation information

SMF 24731–SMF 24734 (point): 33°50ʹN, 73°19ʹE

Additional information

Funding

SK was supported by the Deutsche Forschungsgemeinschaft [grant no. KL2378/2-1].