Extreme diversity and parasitism of Late Jurassic squat lobsters (Decapoda: Galatheoidea) and the oldest records of porcellanids and galatheids Author Robins, Cristina M. Author Klompmaker, Adiël A. text Zoological Journal of the Linnean Society 2019 187 1131 1154 journal article 0024-4082 ADA435F-940B-4F34-B86D-D47D56F30769 FAMILY PORCELLANIDAE HAWORTH , 1825 Included genera [§§exclusively fossil; §fossil and modern; rest exclusively modern]: Aliaporcellana Nakasone & Miyake, 1969 ; Allopetrolisthes Haig, 1960 ; Ancylocheles Haig, 1978 ; Beripetrolisthes §§ De Angeli & Garassino, 2002 ; Capilliporcellana Haig, 1978 ; Clastotoechus Haig, 1960 ; Cretacolana §§ Schweitzer & Feldmann, 2012 ; Disipia §§ Beschin et al., 2016 ; Enosteoides Johnson, 1970 ; Eopetrolisthes §§ De Angeli & Garassino, 2002 ; Euceramus Stimpson, 1860 ; Eulenaois Ng & Nakasone, 1993 ; Heteropolyonyx Osawa, 2001 ; Heteroporcellana Haig, 1978 ; Liopetrolisthes Haig, 1960 ; Lissoporcellana Haig, 1978 ; Lobipetrolisthes §§ De Angeli & Garassino, 2002 ; Longoporcellana §§ Müller & Collins, 1991 ; Madarateuchus Harvey, 1999 ; Megalobrachium Stimpson, 1858 ; Minyocerus Stimpson, 1858 ; Muelleristhes §§ Garassino et al., 2014 ; Neopetrolisthes Miyake, 1937 ; Neopisosoma Haig, 1960 ; Novorostrum Osawa, 1998 ; Orthochela Glassell, 1936 ; Pachycheles § Stimpson, 1858 ; Parapetrolisthes Haig, 1962 ; Paraporcellana § B e s ch i n e t a l., 2 0 1 6; Pe t r o ch e l e s M i e r s, 1 8 7 6; Petrolisthes § Stimpson, 1858 ; Pisidia § Leach, 1820 ; Polyonyx § Stimpson, 1858 ; Porcellana § Lamarck, 1801 ; Porcellanella White, 1852 ; Pseudoporcellanella Sankarankutty, 1961 ; Raphidopus Stimpson, 1858 ; Spathagalathea § De Angeli & Garassino, 2002 ; Ulloaia Glassell, 1938 ; Vibrissalana § Robins & Klompmaker gen. nov. Diagnosis : See Schweitzer & Feldmann (2010b: 243–244) . Discussion : As for Jurellana (see above), considerable debate has surrounded the taxonomic placement of Mesozoic porcellanids. The Late Cretaceous (late Maastrichtian) Petrolisthes inornatus ( Collins et al., 1995 ) from The Netherlands was reassigned to Petrolisthes from the brachyuran Glyptodynomene Van Straelen, 1944 , by Fraaije et al . (2008) . The non-porcellanid galatheoid Paragalathea africana Garassino et al., 2008 , from the Late Cretaceous (Cenomanian–Turonian) of Morocco was transferred to the porcellanid genus Muelleristhes Garassino et al., 2014 . However, Robins et al . (2016) moved it to the galatheoid family Catillogalatheidae because the abdomen was exposed rather than tucked under the carapace as in many Porcellanidae and because of close similarities to other catillogalatheids, such as Vasconilia ruizi ( Van Straelen, 1940 ) (see Klompmaker et al ., 2012a ). We add that the chelipeds ( Garassino et al. , 2014 : pl. 1.3–1.4) are relatively small compared with modern porcellanids ( Haig, 1960 ; Werding & Hiller, 2007 ; Baeza, 2016 ). The mid-Cretaceous (Cenomanian) deposits of France have yielded Porcellana antiqua A. Milne Edwards, 1862 , which Breton & Collins (2007) and Fraaije et al . (2008) considered to be a nomen dubium because Milne Edwards provided only a brief description, showed no illustrations and the holotype appeared untraceable. However, Schweitzer & Feldmann (2012) rediscovered the holotype and erected Cretacolana to accommodate this porcellanid species. The slightly older Annieporcellana dhondtae Fraaije et al., 2008 , from the mid-Cretaceous (late Albian) of Spain was recently transferred to Catillogalatheidae by Robins et al. (2016) . Finally, a specimen from the mid-Cretaceous (late Albian) of Texas ( USA ) was named Petrolisthes albianicus Franţescu, 2014 and suggested to be the oldest representative of that genus ( Franţescu, 2014 ). Franţescu (2014: 227) found that the sternum ‘clearly separates it from [modern non-porcellanid] galatheoids’ and other mid-Cretaceous galatheoids in his study. The sternum indeed appears more rectangular than in modern non-porcellanid galatheoids, which tend to have a triangular sternum overall (e.g. Baba, 2005 ; Macpherson et al ., 2017 ). However, the degree of variation among galatheoid sterna in the Mesozoic is poorly known. Moreover, the thoracic sternite 3 of Petrolisthes albianicus , which is important for the overall shape of the sternum, is incomplete, as are several outer parts of other sternites. Thus, the shape of the sternum is not fully known and more difficult to use than previously assumed. Ascription to Petrolisthes was based on a rectangular carapace outline, weak grooves and the presence of outer-orbital spines ( Franţescu, 2014 ). However, a rectangular carapace is more characteristic of non-porcellanid galatheoids (e.g. Baba, 2005 ; Ahyong et al ., 2010 ; Robins et al ., 2013 , 2016 ), whereas porcellanid carapaces are typically ovate or widen posteriorly (e.g. Haig, 1960 ; De Angeli & Garassino, 2002 ). Franţescu (2014) indicated that this 3.7-mm-wide specimen may have been more rectangular than other Petrolisthes species , because it is a juvenile, as also noted by Müller (1984) for a fossil species. However, Müller (1984) did not figure small specimens or detail the degree of ontogenetic variation of the carapace shape. Furthermore, no marked differences in carapace shape were observed for small vs. large specimens of extant Petrolisthes rufescens (IZG222728). Small (< 5 mm carapace width) specimens of porcellanids from the Eocene–Oligocene of Italy do not show parallel lateral margins as seen in P. albianicus either ( De Angeli & Garassino, 2002 ; Beschin et al ., 2016 ). Although weak carapace grooves are common in porcellanids, they can also be found among paragalatheoids and some catillogalatheids ( Robins et al. , 2016 ), which also applies for outer-orbital spines ( Klompmaker et al ., 2012a ; Robins et al ., 2016 ). Rather than representing a species of Petrolisthes or even a porcellanid, P. albianicus resembles the catillogalatheid Hispanigalathea in nearly all aspects in detail ( Klompmaker et al ., 2012a ; Robins et al ., 2016 ), especially the type species from the same age (late Albian) of Spain , Hispanigalathea pseudolaevis Klompmaker et al., 2012a . The only difference is that the carapace excluding the rostrum is ~5% longer than wide rather than 15–28% according to the 2012 genus diagnosis based on two species. The groove pattern, groove strength, width of rostrum at base, presence of an outer-orbital spine and ornamentation are all comparable to the type species. Thus, we refer Petrolisthes albianicus to Hispanigalathea by expanding the diagnosis somewhat.