Cainozoic Research, 2(l-2)(2002), pp. 109-116,October 2003 obesus a new of hermit crab Ciliopagurus , species Oligocene from northwest Belgium ³ van Bakel John+W.M. ² & René+H.B. Barry+W.M. ¹, Jagt Fraaije 'Schepenhoek 235, NL-5403 GB Uden, the Netherlands:e-mail: [email protected] 2 Natuurhistorisch Museum Maastricht, de Bosquetplein 6, NL-6211 KJ Maastricht, the Netherlands: e-mail: john.jagt@maastricht. nl 2 Oertijdmuseum de Groene Poort, Bosscheweg 80, NL-5283 WB Boxtel, the Netherlands: e-mail: [email protected] Received 21 October 2002; revised version accepted 22 March 2003 The basal portion of the Belsele-Waas Clay Member (Boom Clay Formation, Rupelian, Oligocene) as exposed at the Scheerders van Kerchove (SVK) clay pit, southwest ofSint-Niklaas (province of Oost-Vlaanderen,NW Belgium), has recently yielded materialofa diogenid the hermit crab with annulations and a stridulatory apparatus on the inner surface of cheliped. This is here described as a new taxon, Ciliopagurus obesus n. sp., documentingone of the rare instances where a fossil paguroid maybe assigned with certainty to an extant genus. Previous records of fossil hermit crabs (Paguroidea)are listed. KEY WORDS:: Paguroidea, Diogenidae, Oligocene, Belgium, new species. Introduction Of note is the fact that van Straelen (1921, p. 122) listed but a single Cainozoic pagurid, Pagurus sp., from the ‘Le- Although decapod crustacean remains abound in many dien’ (= Lede Formation, Lutetian, Eocene) ofthe Brussels Cainozoic strata in Belgium, in particular those of Eocene area, based on previous records by Galeotti (1837) and Le and Oligocene age, there are but few modem papers de- Hon (1862). From much younger, Pliocene, strata in the these notable Collins Smith scribing faunas; exceptions are & Antwerp area, van Bakel et al. (2000) listedPagurus sp.; this (1993) and Verheyden (2002). From personal observations, is closely related to or conspecific with P. bernhardus Linne, we know that both public (see also Feldmann & Dhondt, 1758 (see van Bakel et al, in press). The new diogenid material 1991) and private collections contain abundant of described in the present note thus constitutes not only the often exquisitely preserved specimens. In addition to the new thirdhermit crab on record from Cainozoic strata in Belgium, diogenid hermit crab described in the present paper, a new but also the first that is formally named. It is to be expected cancrid from the Lower/Middle Pliocene of Oelegem (van that there will be additionalrecords of Cainozoic pagurids Bakel and and faunules from rich et al, 2003) anomuran brachyuran Belgium, once the collections of molluscs, includ- from the Lillo Formation (Piacenzian, Pliocene) at Kallo ing bulk samples, in particular from Pliocene strata in the (van Bakel et al, in press) will shortly be published. Other Antwerp area, have been meticulously screened. There is and from the indirect evidence in the form of broken and/or abraded projects (e.g., linuparids brachyurans Ypresian or (Eocene) of Marke, Oligocene stomatopods from Sint- encrusted/bored gastropod shells (compare Ehrenberg, 1931; Niklaas) are underway. Walker, 1988, 1989, 1992), which are known from various The most complete, albeit outdated, listing ofCainozoic localities and stratigraphic levels. decapod crustaceans from Belgium is still that by van Straelen strata of he (1921). From Oligocene age, recorded a single nephropid lobster (Homarus perceyi van Beneden, Fossil paguroid records crab 1872), a geryonid (Coeloma rupeliense Stainier, 1887) well Portunus nodosus Hermit crabs as as van Beneden, 1883. According (Paguroidea) are obligatory occupants ofempty to Verheyden (2002), the last-named taxon is a nomen gastropod and other molluscan shells, which explains why nudum based the Stainier later ; on same material, (1887) their often dissociated remains are fairly common in shell- erected its valid Coeloma These rich name, rupeliense. two deposits, such as coquinas. With the exception of a from the species Boom Clay Formation, also illustrated by handful ofrecords documenting in situ preservation offossil have been within Geys & Marquet (1983, pi. 57, figs 1,2), recently pagurids molluscan shells (see e.g., Hyden & Forest, revised by Verheyden (2002). 1980; Feldmann & Keyes, 1992; Hu & Tao, 1996; - 110- McLaughlin & Forest, 1997; Jagt et al, 2000; Karasawa, Angeli, 1995, 2000; Vicariotto, 1997); 2002; Fraaije, 2003), most occurrences comprise isolated Spain (Via, 1959; Sole & Via, 1989); major claws (chelipeds). On account of their characteristic Hungary (Muller, 1975, 1979, 1984; Muller & Collins, such claws and morphology, are easily recognised as pagurid 1991); distinguished from associated anomuran and brachyuran Poland(Forster, 1979; Muller, 1996); chelipeds. Kyushu, Boso Peninsula and Ainoshima Island, Japan For the most recent discussion of fossil hermit crabs, (Karasawa & Inoue, 1992; Kato & Karasawa, 1998; reference is madehere to Schweitzer & Feldmann(2001) and Karasawa, 1993, 1997,2002); Schweitzer et al. (2002). These authors notedthat the Pagu- Taiwan(Hu & Tao, 1996); roidea known in the fossil reord in Zealand as currently are urgent New (Hyden & Forest, 1980; McLaughlin & need ofrevision; most fossil taxa have typically, and often Forest, 1997). routinely, beenreferred to the Diogenidae or Paguridae, thus the level. Characters the masking true diversity at family impor- In present note we describe a new species of diogenid tant at the generic level include morphological features of fromRupelian (Oligocene) strata exposed near Sint-Niklaas, dorsal carapace, abdomen, mouthparts, and appendages which we assign to the genus Ciliopagurus Forest, 1995a. than the which (other chelipeds), are rarely preserved in Forest (1995a) subdivided the widely distributed diogenid fossils. genus Trizopagurus Forest, 1952 into the genera Trizopagu- For most fossil hermit crabs, only (a) major claw(s) is rus Strigopagurus, and Ciliopagurus as based on the proper, , (are) available; however, based on claw shape, size and shape ofthe cephalothoracic shield, the ornament ofthoracic ornament, a rough generic placement has generally proved appendages, the organisation of pleopods and the develop- possible. This is the case for Cretaceous pagurids which have ment of stridulatory structures on chelipeds. In a subsequent beenrecorded from; paper (Forest, 1995b), he reassigned a Miocene species from Hungary to Ciliopagurus, making reference to its stridulatory and features. Alabama, Arkansas, Texas, Mississippi New Jersey The new species described here shows well- (USA; see Rathbun, 1935; Stenzel, 1945; Roberts, developed stridulatory structures as well, and extends the 1962; Whetstone & Collins, 1982; Bishop, 1983a,b, range of the genus Ciliopagurus downwards for another 15 1986a, b); Ma. Mexico (Vega et al, 1995); Germany (Merlin, 1941); northeast Belgium and the southeastNetherlands(Collins Systematic description et al, 1995; Jagt et al, 2000, work under way); France (de Tribolet, 1875); Abbreviation- Type specimens are deposited in the collec- Spain (Sole & Via, 1989); tions of the Oertijdmuseum de Groene Poort, Boxtel (the Antarctica (Aguirre-Urreta & Olivero, 1992; Olivero & Netherlands; abbreviation MAB). Aguirre-Urreta, 1994). Superfamily Paguroidea Latreille, 1802 These have been assigned to the genera Paguristes Dana, Family Diogenidae Ortmann, 1892 1851, Pagurus Fabricius, 1775 (s. lat), Palaeopagurus van Genus Ciliopagurus Forest, 1995a, p. 43 Straelen, 1925,Petrochirus Stimpson, 1858;Bishop (1983a) and erected and — Cancer Bishop (1986b) new genera, Roemerus Type species strigatus Herbst, 1804, by original Parapaguristes, respectively. designation. Cainozoic pagurids have mostly been assigned to the Calcinus genera Anapagurus Henderson, 1888, Dana, 1851, Ciliopagurus obesus n. sp. Dardanus Paul’son, 1875, Diacanthurus McLaughlin & Forest, 1997, Diogenes Dana, 1851, Eocalcinus Via, 1959, Figures 1,2 Pagurus (s. lat.), Paguristes, Petrochirus and Pylopagurus A. Milne Edwards & Bouvier, 1891, often with a query. Such Diagnosis - Heterochelous diogenid, with identical shape records include: and ornament of claws, stridulatory structures less pro- nouncedin minorclaw; ornament oftransverse, more or less Chiapas, Mexico (Vega et al, 2001); evenly distributed, entire striae, beaded in some larger Jamaica (Morris, 1993; Collins et al, 1996; Collins & specimens. Portell, 1998); North and South and California — Carolina, Washington Derivation ofname Latinobesus, meaning thick, bulky, in (USA; Rathbun, 1926; Blow & Manning, 1996; reference to the shape and size of the major claw. Schweitzer & Feldmann, 2001); Netherlands Material— the (Holthuis, 1949); Holotype, a leftpropodus, is MAB k.2365 (leg. Austria (Glaessner, 1928; Bachmayer, 1951); T. Lambrechts) (Figures 1/1-3; 2/1); paratype, a right cheli- northern Italy (Beschin et al, 1994, 2000, 2002; de ped, is MAB k.2366 (leg. FH. Mollen)(Figure2/2, 3). -Ill - 1. MAB Member Figure Ciliopagurus obesus n. sp., k.2365 (holotype), basal portion of the Belsele-Waas Clay (Boom Clay Formation ; SVK 1 - Rupelian, Oligocene) ofthe clay pit near Sint-Niklaas (Belgium); detail ofstridulatory apparatus (scale bar equals 1 mm); 2, 3 - inner and dorsal aspects, respectively, of left propodus (scale bar equals 2 mm) (SEM). - 112- MAB and MAB basal of the Figure 2. Ciliopagurus obesus n. sp., k.2365 (holotype) k.2366 (paratype), portion Belsele-Waas Clay Member (Boom Clay Formation ; Rupelian, Oligocene) ofthe SVK clay pit near Sint-Niklaas