Ilia nucleus (Linnaeus, 1758)

Garassino, Alessandro, Pasini, Giovanni, Angeli, Antonio De & Hyžný, MatÚš, 2014, The decapod fauna (Axiidea, Anomura, Brachyura) from the Late Pleistocene of Trumbacà, Reggio Calabria (Calabria, southern Italy), Natural History Sciences 1 (2), pp. 119-130 : 124

Ilia nucleus (Linnaeus, 1758)

Fig. 2B

Material and measurements: One complete carapace (MSNM i27903 – lcxp: 10 mm; wcxp: 7 mm).

Discussion. Zariquiey Álvarez (1968) pointed out the main diagnostic characters of Ilia nucleus , as follows: typical globular carapace, slightly longer than wide; very narrow subacutely bidentate front; posterior margin with well-developed, rounded two median lobes, and one strong spine upward-directed on either lateral margins. We ascribe the studied specimens to the extant I. nucleus , because it shares the same above-mentioned morphological characters. A review of the morphological characters of this species carried on by Garassino and Pasini (2012), pointed out that all the specimens previously reported from the Pliocene of Italy and erroneously ascribed to I. pliocaenica Ristori, 1891 , should be instead ascribed to I. nucleus (for discussion see Garassino et al., 2010 a, 2012, 27-30; Garassino & Pasini, 2012, 43-46). Moreover I. nucleus , was recently reported from the Early Pleistocene (Emilian) of Pomezia (Roma, Lazio, central Italy) ( Garassino et al., 2010a; Garassino & Pasini, 2012), and from the Zanclean (Early Pliocene) of “La Serra” quarry ( Pisa , Tuscany, central Italy) by Garassino et al. (2012). Extant I. nucleus is widespread in the Mediterranean Sea, living imbedded in sandy bottoms from 5 to 160 meters deep.

Note. The studied specimen shows direct evidence of a predation consisting of an ovoid submillimetric drilled hole into the dorsal gastric region. This kind of holes (ichnotaxon Oichnos ovalis ) has been attributed to possibly octopods with some figured examples ( Klompmaker et al., 2013: 606, 605, fig. 3). Similar boreholes of compa- rable size and form, were previously reported also from the fossil decapod leucosiid Ristoria pliocaenica (Ristori, 1891) from the Early Pliocene of the “La Serra” quarry by Pasini & Garassino (2012: 263, 261, Fig. 3 A, B ). This report expands the scarce record on fossil decapod crab predation found in the worldwide Cenozoic (for discussion see Klompmaker et al., 2013).

Figures

Fig. 2 - A) Ebalia cf. E. deshayesi Lucas, 1846, MSNM i27902, carapace in dorsal view (x 12). B) Ilia nucleus (Linnaeus, 1758), MSNM i27903, carapace in dorsal view (x 6). C) Medorippe lanata (Linnaeus, 1767), MSNM i27884, carapace in dorsal and ventral views (x 2). D) Calappa granulata (Linnaeus, 1758), MSNM i27906, incomplete carapace in dorsal view (x 4.6). E) Calappa granulata (Linnaeus, 1758), MSNM i27893, right chela, outer view (x 2.5).

Fig. 3 - A) Pisa armata (Latreille, 1803), MSNM i27880, right chela, outer and inner views (x 3.2). B) Atelecyclus undecimdentatus (Herbst, 1783), MSNM i27879, right chela, outer view (x 3.7). C) Pilumnus hirtellus (Linnaeus, 1761), MSNM i27904, carapace in dorsal view (x 8.5). D) Pilumnus hirtellus (Linnaeus, 1761), MSNM i27912, right chela, outer and inner views (x 7.5). E) Xantho cf. X. incisus (Leach, 1814), MSNM i27908, left chela, outer and inner views (x 4.6).