Ranina ornata De Angeli & Beschin, 2011

Pasini, Giovanni & Garassino, Alessandro, 2017, A preliminary review of the fossil species of Ranina Lamarck, 1801 (Decapoda, Brachyura, Raninidae), with systematic remarks, Natural History Sciences 4 (1), pp. 43-72 : 56-57

? Ranina ornata De Angeli & Beschin, 2011

Fig. 11

Ranina ornata De Angeli & Beschin, 2011: 13-15 , fig. 2, Tab. 1 .

Ranina ornata - Karasawa et al. 2014: 45, tab. S6. – Baldanza et al. 2014: 276, fig. 8C. – Karasawa et al. 2014: 260. – Famiani et al. 2015: 344.

Type material: holotype, MCZ3391 -I.G.336929.

Type locality: Pradipaldo (Marostica, Vicenza, NE Italy) .

Geological age: middle Eocene (Lutetian).

Examined material: holotype.

Description by De Angeli & Beschin (2011): “ Carapace a forma di scudo, convesso in senso trasversale, più lungo che largo e maggiormente allargato nella parte anteriore; il margine orbito-frontale occupa l’intera parte anteriore del dorso; il rostro é conservato dalla sola base e i margini sopraorbitali sono incompleti; il dente postorbitale é largo alla base, convesso sul margine esterno, ben proiettato in avanti ed appuntito nella parte distale; i margini antero-laterali sono convessi ed ornate da due denti piatti: il primo dente é subtriangolare, con margine esterno curvo, appuntito distalmente e diretto anteriormente; il secondo dente é piatto, rivolto obliquamente verso l’esterno e suddiviso in tre acute spine sul margine distale; la prima spina é più sottile e di minori dimensioni rispetto alle altre due; i margini postero-laterali sono leggermente curvi, convergenti al margine posteriore ed ornate da una cresta granulata ; il margine posteriore si mostra rettilineo nella parte mediana e convesso e carenato superficialmente ai lati; le regioni dorsali non sono distinte; i solchi branchio-cardiaci appaiono poco evidenti e paralleli; la superficie anteriore e le regioni epatiche sono ornate da tubercoli appuntiti, ben pronunciati e disposti in allineamenti trasversali leggermente sinuosi; una simile ornamentazione, però a tubercoli più minuti, é presente anche sui denti orbitali e antero-laterali; sulla parte mediana e posteriore del dorso i tubercoli hanno forma triangolare, estesi anteriormente, molto fitti e disposti in allineamenti che hanno una leggera convessità posteriore. ”

Literal translation: carapace shield shaped, convex transversally, longer than wide; wider anteriorly; frontorbital margin wide as the anterior dorsal part (of the carapace); only the bottom part of the rostrum is preserved; incomplete supraorbital margins; postorbital spine wide at the base, convex along the outer margin, well forward projected and pointed distally; convex anterolateral margins with two flat spines; first anterolateral spine subtriangular, with curved outer margin, pointed distally and anteriorly directed; second anterolateral spine flat, outward directed and with three acute spines distally; the first spine thin and smaller than the others two; posterolateral margins slightly curved, narrowing posteriorly and ornamented by a grained ridge; straight posterior margin convex medially, and with a carinate surface on the lateral margins; indistinct dorsal regions; branchiocardiac grooves smooth and parallel; dorsal anterior surface and hepatic regions with small pointed tubercles, protruding and ranged in transversal lines, slightly sinuous; similar ornamentation, but with smaller tubercles, is present also on the orbital and anterolateral spines; on the median and posterior dorsal part (of the carapace) the tubercles are triangular, forward protruding, close each to others and ranged in small groups slightly convex posteriorly.

Discussion. De Angeli & Beschin (2011), described R. ornata , justifing the assignment to Ranina because “ though the specimen lacks the frontal part, the morphological characters are typical of the genus Ranina Lamarck, 1801 ”. Moreover, the authors justified the new species due to the “different dorsal ornamentation that, especially concerning the dorsal and posterior dorsal parts, result characteristic and almost unique for this genus” ( De Angeli & Beschin, 2011: 14 - literal translation from the original Italian text).

Based upon the review of the holotype, we disagreee with the authors’ assignment, following the most recent diagnosis by Karasawa et al. (2014). Indeed, the anterolateral spines are “ bifid or trifid ” in Ranina ( Karasawa et al., 2014: 260) , whereas the first anterolateral spine is pointed, triangular and the second one trifid in R. ornata . Moreover the lack of the rostrum does not allow a confident assignment to the genus. The carapace is very deformed and incomplete and, though its general shape resembles that of all representatives of the Raninidae sensu stricto, the dorsal median and posterior ornamentation are quite different from Ranina , as pointed out by the authors themselves.

In conclusion we question the placement of ornata within this genus based upon the poorly preserved, deformed carapace and above all the lack of important distinctive characters, such as the rostrum, the different shape of the anterolateral spines, and the peculiar dorsal ornamentation.

Figures

Fig. 11 -?Ranina ornata De Angeli & Beschin, 2011; holotype, MCZ3391-I.G.336929 (x 1.8).