Hydrotrupes

Sharp, 1882

Species Guides

Hydrotrupes palpalis

Hydrotrupes is a of diving beetles (Dytiscidae: Agabinae) established by Sharp in 1882. The genus contains three : two extant (H. chinensis in eastern China and H. palpalis in western North America) and one fossil (H. prometheus from Eocene Baltic amber). The fossil record establishes Hydrotrupes as at least 40 million years old and demonstrates remarkable morphological conservation over this timespan. The current disjunct distribution of living species is interpreted as a relict of a formerly widespread distribution across northern continents during the Eocene.

Hydrotrupes palpalis by (c) Trevor Van Loon, some rights reserved (CC BY), uploaded by Trevor Van Loon. Used under a CC-BY license.

Pronunciation

How to pronounce Hydrotrupes: /haɪˈdrɒtɹuːpiːz/

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Identification

Hydrotrupes are distinguished within Agabinae by morphological features conserved since the Eocene, as evidenced by the fossil H. prometheus. Specific diagnostic characters for the include those typical of the tribe Hydrotrupini. For species-level identification, H. chinensis and H. palpalis are separated by geographic distribution (China versus western North America) and subtle morphological differences detailed in species-level descriptions.

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Distribution

Extant occur in western North America (H. palpalis) and eastern China (H. chinensis), representing a disjunct distribution. The fossil species H. prometheus from Baltic amber indicates the was present in Europe during the Eocene, supporting a formerly widespread distribution across northern continents that has since contracted.

Similar Taxa

Other Agabinae generaHydrotrupes is distinguished within Agabinae by its membership in tribe Hydrotrupini and by morphological features conserved since at least the Eocene, as demonstrated by the fossil record.

More Details

Fossil significance

Hydrotrupes prometheus from Baltic amber is currently the oldest known fossil assigned to Agabinae and one of few diving described from fossiliferous amber. The specimen's similarity to living Hydrotrupes indicates substantial morphological conservation in this lineage.

Biogeographic history

The Eocene occurrence of Hydrotrupes in Europe, combined with extant in North America and China, supports the hypothesis that this represents a trans-Beringian lineage with a formerly widespread northern distribution.