Extreme diversity and parasitism of Late Jurassic squat lobsters (Decapoda: Galatheoidea) and the oldest records of porcellanids and galatheids Robins, Cristina M. Klompmaker, Adiël A. Zoological Journal of the Linnean Society 2019 187 1131 1154 B3HHL HAWORTH, 1825 HAWORTH 1825 [327,706,1807,1832] Malacostraca Porcellanidae CoL,GBIF Animalia Decapoda 9 1140 Arthropoda family   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 Netherlandswas reassigned to  Petrolisthesfrom 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 Moroccowas transferred to the porcellanid genus  Muelleristhes Garassino et al., 2014. However,  Robins et al. (2016)moved it to the galatheoid family Catillogalatheidaebecause the abdomen was exposed rather than tucked under the carapace as in many Porcellanidaeand 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 Francehave yielded  Porcellana antiquaA. Milne Edwards, 1862, which Breton & Collins (2007)and Fraaije et al. (2008)considered to be a nomen dubiumbecause Milne Edwards provided only a brief description, showed no illustrations and the holotypeappeared untraceable. However, Schweitzer & Feldmann (2012)rediscovered the holotypeand erected  Cretacolanato accommodate this porcellanid species. The slightly older  Annieporcellana dhondtae Fraaije et al., 2008, from the mid-Cretaceous (late Albian) of Spainwas recently transferred to Catillogalatheidaeby  Robins et al.(2016). Finally, a specimen from the mid-Cretaceous (late Albian) of Texas( USA) was named  Petrolisthes albianicus Franţescu, 2014and 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  Petrolistheswas 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  Petrolisthesspecies, 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 mmcarapace width) specimens of porcellanids from the Eocene–Oligocene of Italydo not show parallel lateral margins as seen in  P. albianicuseither ( 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  Petrolisthesor even a porcellanid,  P. albianicusresembles the catillogalatheid  Hispanigalatheain nearly all aspects in detail ( Klompmaker et al., 2012a;  Robins et al., 2016), especially the typespecies 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 typespecies. Thus, we refer  Petrolisthes albianicusto  Hispanigalatheaby expanding the diagnosis somewhat.