A New Varunid Subfamily (Decapoda, Brachyura, Grapsoidea, Varunidae) for Crabs From European and West African Waters, With the Description of Two New Genera and Two New Species.

Abstract

The subfamily Asthenognathinae is currently composed of a single genus, Asthenognathus Stimpson, 1858, with three species, A. inaequipes Stimpson, 1858, A. hexagonus Rathbun, 1909 (both from the Indo-West Pacific), and A. atlanticus Monod, 1933 (European and West Tropical African waters). All Asthenognathus species are difficult to collect due to their small size and symbiotic lifestyle with fossorial organisms. The examination of specimens of A. atlanticus from European and West African waters deposited in scientific collections shows significant morphological and molecular differences with the Indo-West Pacific species, which makes the creation of a new subfamily (Schubartinae n. subf.) and two new genera necessary. The identity of A. atlanticus, the only species found along the East Atlantic and Mediterranean waters, is clarified, and a new genus, Dudekemus n. gen., is established for this species, Dudekemus atlanticus (Monod, 1933) n. gen., n. comb. This study also describes another new genus, Schubartus n. gen., based on morphological differences and genetic data. These two new genera can be distinguished from Asthenognathus by the carapace proportions and differences in the structures of the male pleonal somites, pereiopods and endostome. In addition, two new species distributed in Guinea-Bissau and Mauritania, Schubartus mauritanicus n. gen., sp. nov., and S. ngankeeae n. gen., n. sp., are described. A key for species of the subfamilies Asthenognathinae and Schubartinae n.subf. is provided.