Natural History Sciences. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano, 4 (1): 87-96, 2017 DOI: 10.4081/nhs.2017.323 A new raninoid crab (Decapoda, Brachyura, Raninidae) from the early Oligocene (late Rupelian) of Italy Giovanni Pasini1, Alessandro Garassino2* Abstract - Pasini & Garassino (2017) did a preliminary systematic Ranina berglundi Squires & Demetrion, 1992, dell’Eocene inferiore del review of the worldwide fossil species of Ranina, pointing out that it Messico, che è stata a sua volta assegnata a A. berglundi (Squires & was used as “basket genus” for almost two centuries to accommodate Demetrion, 1992) n. comb. different questionable taxa pertaining or not to Raninoidea. The result was that just four species were possibly assigned to Ranina compared Parole chiave: Decapoda, Brachyura, Raninidae, Oligocene, Italia to 23 species previously listed by Karasawa et al. (2014). Among the nord-occidentale. studied species, a rich sample of specimens from the early Oligocene of the Ligure-Piemontese Basin (Italy), previously assigned to Ranina speciosa by Ristori (1889) and Allasinaz (1987), has been revised and here discussed. The studied specimens are herein assigned to the new INTRODUCTION genus Alcespina, with A. ovadaensis n. sp (Raninidae), whereas five Ristori (1889) and Allasinaz (1987) reported some specimens of Allasinaz’s original sample are assigned to Raninoides well-preserved specimens from several localities of the H. Milne Edwards, 1837. Finally, this study allows us to review the early Oligocene Ligure-Piemontese Basin (NW Italy) as- questionable species Ranina berglundi Squires & Demetrion, 1992, from the early Eocene of Mexico, herein also assigned to A. berglundi signing them to Ranina (Ranina) speciosa (von Münster, (Squires & Demetrion, 1992) n. comb. 1840). Later De Angeli & Beschin (2011: 16) discussed the assignment, pointing out that the specimens had more clo- Key words: Decapoda, Brachyura, Raninindae, Oligocene, NW se affinities with R. bouilleana A. Milne Edwards, 1872. Italy. Recently, Pasini & Garassino (2017) considered R. bouilleana and R. speciosa as questionable Ranina spe- Riassunto - Un nuovo raninoide (Decapoda, Brachyura, Ranini- cies, since the type material of both species does not pre- dae) dell’Oligocene inferiore (Rupeliano superiore) d’Italia. serve enough diagnostic characters for a specific systema- Pasini e Garassino (2017), hanno effettuato una preliminare revi- tic assignment. sione sistematica delle specie fossili mondiali attribuite a Ranina, evi- Indeed a close review of the original sample by Alla- denziando come il genere sia stato usato per almeno due secoli come un “contenitore” nel quale raccogliere discutibili taxa appartenenti, e non, sinaz (1987) including carapaces, some pleonal parts, and alla superfamiglia Raninoidea. Risultato della revisione è stato quello thoracic appendages allows us to assign the studied spe- di ridurre a sole quattro le specie possibilmente attribuibili a Ranina, cimens to Alcespina n. gen., with A. ovadaensis n. gen., rispetto alle 23 precedentemente elencate da Karasawa et al. (2014). n. sp. (Raninidae), based upon diagnostic fossil characters Fra le specie attribuite a Ranina, un ampio campione di esemplari pro- (‘proxy characters’, sensu Schweitzer, 2003) detected and venienti dall’Oligocene inferiore del bacino Ligure-Piemontese, prece- here discussed, whereas five smaller specimens conside- dentemente attribuiti a Ranina speciosa da Ristori (1889) e Allasinaz (1987), è stato qui riesaminato e discusso. I campioni studiati sono stati red by Allasinaz (1987: 533, Pl. 1, figs. 12-16), as molting assegnati al nuovo genere Alcespina con A. ovadaensis n. sp (Rani- carapace of juvenile individuals of Ranina (Ranina) spe- nidae), mentre cinque esemplari del campione originale di Allasinaz ciosa, have instead been ascribed to Raninoides cf. R. plio- (1987) sono stati attribuiti a Raninoides H. Milne Edwards, 1837. Inol- cenicus De Angeli, Garassino & Pasini, 2009. Finally, this tre il presente studio ha permesso di revisionare anche la dubbia specie study allows a review of the systematics of the questiona- ble species Ranina berglundi Squires & Demetrion, 1992, from the early Eocene of Mexico, herein ascribed to Alce- 1 Via Alessandro Volta 16, 22070 Appiano Gentile (CO), Italia. spina berglundi (Squires & Demetrion, 1992) n. comb. E-mail: [email protected] 2 Sezione di Paleontologia degli Invertebrati, Museo di Storia Naturale, Corso Venezia 55, 20121 Milano, Italia. MATERIALS AND METHODS * Corresponding author: [email protected]; The studied specimens were collected at several loca- [email protected] lities located behind the Bormida and Stura Rivers (Cas- sinelle, Ciglione, Ponzone, Rio Volpina, Alessandria, sou- © 2017 Giovanni Pasini, Alessandro Garassino thern Piedmont, NW Italy) (Fig. 1) and Giusvalla (Savona, Received: 16 November 2016 Liguria, NW Italy), along the Ligure Piemontese Basin, Accepted for publication: 2 March 2017 from transitional sandy-marl layers pertaining to the upper Molare Formation, to the Rigoroso Marl, both ascribed to 88 Giovanni PASINI, ALESSANDRO GARASSINO Fig. 1 - Map of studied area depicting main fossiliferous localities in Alessandria province. (after Allasinaz, 1987). the late Rupelian (early Oligocene) (for full references see Included genera – Alcespina nov. (present study); Allasinaz, 1987: 513). These sediments were deposited Lophoranina Fabiani, 1910; Lophoraninella Glaess- at the bottom of a shallow marine coastal environment, ner, 1936; Ranina Lamarck, 1801; Raninella A. Milne including copious invertebrate fossils of nummulites, br- Edwards, 1862; Remyranina Schweitzer & Feldmann, yozoans, mollusks, echinoderms, terrestrial plant remains, 2010; Vegaranina Van Bakel, Guinot, Artal, Fraaije & and a few different fossil crabs (for full list see: Allasinaz, Jagt, 2012. 1987). The studied sample includes 23 selected specimens of the original 36 examined (MPOM 4, 5, 10, 11, 13, 20, Genus Alcespina nov. 21, 23, 39, 171, 288, 290, 701, 1770, 1776, 1779, 1780, C1, C3, RMT, 17MT, 137M, 139M), housed in the col- Diagnosis: carapace ovate, wide fronto-orbital margin lections of the Museo Paleontologico ”G. Maini”, Ovada convex; trifid pointed rostrum, depressed medially; first (Alessandria) (MPOM). anterolateral spine bifid, forward directed, parallel to the Remarks. All specimens of Alcespina ovadaensis middle longitudinal axis; second wide anterolateral spine n. gen., n. sp. were preserved within sub-nodular sandy pointed, flat, strongly outward directed, forming by the hardened concretions, found in association with the fossil straight upper margin, an angle around 90° to the carapace crabs, Coeloma vigil A. Milne Edwards, 1865 and scar- middle line, with triangular unequal serrate spines (3-4) ce portunoid crabs (P. Damarco pers. comm., 2016). The on the upper margin; dorsal regions indistinct. specimens herein assigned to Raninoides cf. R. plioceni- Type species: Alcespina ovadaensis n. sp. cus De Angeli, Garassino & Pasini, 2009, were collected Included fossil species: Alcespina berglundi (Squires only from the Rigoroso Marl layers, revealing a different & Demetrion, 1992) n. comb. (this paper). depositional environment and possible different habitat Etymology: from Alces (elk), and spina (spine), allu- both for Alcespina and Raninoides. ding to the second anterolateral spines shape, remembe- Abbreviations. Ctw: carapace total wide (including ring elk horns. anterolateral spines); Ctl: carapace total length (including Geological range: early Eocene – early Oligocene. rostrum); IGM: Coleción Nacional de Paleontología, Me- Palaeogeographic distribution: the genus is repor- xico; MHN-UABCS: Museo de Historia Natural, Univer- ted from the NE Pacific [Alcespina berglundi (Squires & sidad Autónoma de Baja California Sur (Mexico); MN- Demetrion, 1992) n. comb.] and Mediterranean area (A. HM: Muséum national d’Histoire naturelle, Paris (Fran- ovadensis n. sp.); probably also reported in the NE At- ce); MPOM: Museo Paleontologico”G. Maini”, Ovada, lantic (Biarritz, SE France) with R. bouilleana A. Milne Alessandria (Italy); s1-s6: somite1 to somite 6. Edwards, 1872. Description: as for type species. Discussion: we justify the description of the new ge- SYSTEMATIC PALEONTOLOGY nus, in having a unique combination of distinctive charac- ters within the Ranininae, different from the other genera Infraorder Brachyura Latreille, 1802 ascribed to the subfamily, as follows: Section Raninoida Ahyong, Lai, Sharkey, Colgan & Ng, - Lophoranina Fabiani, 1910, has distinct carapace 2007 surface with typical transverse tegulate rims, usually Superfamily Raninoidea De Haan, 1839 parallel to one other, two anterolateral spines bifid, Family Raninidae De Haan, 1839 broad sternum with C-shaped concave lateral mar- Subfamily Ranininae De Haan, 1839 gins. A NEW RANINOID CRAB (DECAPODA, BRACHYURA, RANINIDAE) FROM THE EARLY OLIGOCENE (late RUPELIAN) OF ItalY 89 - Lophoraninella Glaessner, 1936, has carapace with gions with spiny tubercles frontally directed (Fig. 2). Convex short scabrous ornamentation in anterior third, serrate tran- front wide; trifid rostrum depressed medially, bounded on sverse rimmed ornamentation on remainder of carapace. either bottom side by symmetrical lateral divergent triangu- - Ranina Lamarck, 1801, has triangular rostrum, smal- lar rostral teeth serving as inner-orbital spines (Fig. 2). Wide ler orbital spines, two anterolateral palmate spines that are