A new hermit crab (Anomura, Paguroidea) out of its shell from the middle Eocene Arguis Formation, (Huesca, Spain)

Abstract

Semi-articulated paguroids are rare fossils, and there are only few records from Cenozoic strata. Here we present a new and exceptionally preserved hermit crab (Diogenidae) from the Eocene of Huesca (Spain) that preserves the anterior part of the carapace, together with appendages. Diogenes augustinus sp. nov. represents one of most completely preserved hermit crabs known to date, providing crucial information to understand the evolution of the family Diogenidae. It is characterized by poorly marked regions of shield, absence of Y-line and markedly unequal and robust chelipeds. The specimen is preserved out of its host shell suggesting rapid burial in siliciclastic strata of a prodeltaic environment.

Filling the early Eocene gap of paguroids (Decapoda, Anomura): a new highly diversified fauna from the Spanish Pyrenees (Serraduy Formation, Graus-Tremp Basin)

“…Via (1959) first described Pagurus marceti , Pagurus marini , and Eocalcinus eocenicus on the basis of fragmentary material. Ferratges et al (2020) described a nearly complete specimen of Diogenes augustinus , and Ferratges et al (2021b) recently described two new species ( Parapetrochirus robustus and Eocalcinus gerardbretoni ) from the lower and upper Eocene, respectively.…”

“…Hermit crabs (superfamily Paguroidea Latreille, 1802) are an interesting and diverse group of decapod crustaceans with a widely distributed but fragmentary fossil record (i.e., Via, 1959;Beschin et al, 2002Beschin et al, , 2005Beschin et al, , 2010Beschin et al, , 2012Garassino et al, 2009a, b;Garassino, 2010a, b, 2011;Fraaije et al, 2011Fraaije et al, , 2015Fraaije et al, , 2020Schweigert et al, 2013;Fraaije, 2014;Garassino et al, 2014;Hyžný et al, 2016;De Angeli and Caporiondo, 2017;Ferratges et al, 2020Ferratges et al, , 2021aMironenko, 2020;Ossó, 2020;Pasini et al, 2020) that extends back to the Jurassic (see Fraaije et al, 2022). This is due in part to their highly specialized morphology with poorly mineralized pleon adapted to life inside empty shells or other cavities (e.g., Lemaitre, 1989Lemaitre, , 1990Walker, 1992;de Forges et al, 2001).…”

New hermit crab species (Anomura, Paguroidea) from the upper Miocene St. Marys Formation of Maryland (USA), preserved in their host shells

“…In addition, there are younger (Paleogene and Neogene) records from Kaliningrad, Russia (Eocene; Jagt et al 2006), Denmark (Eocene; Collins & Jakobsen 2004), northern Italy (Eocene; Garassino et al 2009a, Pliocene;Pasini & Garassino 2010), Spain (Eocene;Ferratges et al 2021Ferratges et al , 2022, Austria (Eocene; Fraaije & Polkowsky 2016), Japan (Oligocene; Karasawa 2002), Washington State (USA) (Oligocene; Pasini et al 2020), the Netherlands (Miocene; Jagt et al 2006), Taiwan (Miocene;Hu & Tao 1996), New Zealand (Miocene;Hyden & Forest 1980;Feldmann & Keyes 1992), Panama (Miocene;Todd & Collins 2006), California (USA) (Pliocene; Dunbar & Nyborg 2003) and Taiwan (Holocene; Hu & Tao 1996). A notable recent example is that of a completely preserved hermit crab outside its host gastropod shell from the Eocene of Spain (Ferratges et al 2020).…”