A new xanthid crab, Neoliomera zovoensis sp. nov. (Decapoda, Brachyura), from the Lower Eocene beds of Zovo (Vestenanova, Verona, northeast Italy)

A new species of Neoliomera Odhner, 1925, Neoliomera zovoensis sp. nov. from the Lower Eocene (Ypresian) of Zovo (Vestenanova, Verona), which co-occurs with other decapod crustacean species in a richly fossiliferous coral-algal-reef in the Monti Lessini (Verona area, northeast Italy) is herein described.


Introduction
The rich arthropod fauna from the Paleogene levels in the Veneto region, which includes mysidaceans, isopods, stomatopods, and decapod crustaceans, has been recorded over the last two centuries. The decapod crustacean assemblage is rich in genera and species (see Fabiani, 1910;De Angeli & Beschin, 2001). Recent fieldwork has yielded numerous new decapod species in association with a bioherm or a small sized coral reef (for a checklist of species and complete references see De Angeli & Garassino, 2006;.
Above the Scaglia Rossa (Late Cretaceous, Campanian) follows the so-called "Calcari di Spilecco" (late Paleocene-early Eocene), which is in turn overlain by Lithothamnium and Nummulites limestones, the fish-bearing strata of Pescara and Monte Postale, and the Alveolina limestones, plus marine, brackish, and terrestrial limestones of Monte Postale. Higher upsection, Alveolina and Nummulites limestones are exposed (hamlet of Brusaferri), a thick volcanic mass, containing terrestrial plants and freshwater molluscs (Monte Vegroni), shales with Cypris ostracod shells, and a coal bed with crocodilian and turtle remains (Monte Purga). The uppermost unit, at the top of Monte Purga, comprises columnar basalts. The uppermost stratified limestones along the northern side of Purga di Bolca are dated as late Ypresian (Barbieri & Medizza, 1969). The age of the reptile-bearing coal beds is still uncertain, but could possibly be Lutetian (middle Eocene).
The studied specimen was collected from white crystalline limestones with alveolinid and nummulitid foraminifera (Brusaferri Limestones), which also contain volcanic material, to the southeast of Bolca, along the road connecting Zovo and the hamlet of Vallecco (Fig. 1). The fossiliferous level at Zovo, containing coralligenous algae, corals, micro foraminifera, scarce molluscan internal moulds, and exuviae of small-sized decapod crustaceans, was associated with a bioherm or a small-sized coral reef, which originated within the Alpone Agno graben. Formations such as this have been recorded from the Valle del Chiampo between Mussolino and Zovo di Castelvecchio (De Zanche, 1965) and along the eastern margin of Monti Lessini (Beschin et al., 2007;De Angeli & Garassino, 2002;De Angeli & Ceccon, 2012). Currently, the decapod crustacean assemblage from Zovo includes 24 species (for complete references see Beschin et al. 2016;De Angeli et al., 2019).

Material
One carapace preserving its entire cuticle within a small piece of coralligenous rock. It is housed in the palaeontological collection of the Museo Civico "D. Dal Lago" of Valdagno, Vicenza (MCV).

Systematic palaeontology
For the higher-level classification, we follow the arrangement proposed by Schweitzer et al. dia Odhner, 1925 (fossil and extant), N. kuohwai Hu, 1981 (fossil), N. minuta Beschin, Busulini & Tessier, 2015 (fossil) margins, with four short spiny lobes; fourth anterolateral lobe with granulate ridge extending on branchial region; short, convergent posterolateral margins; undifferentiated dorsal regions; one longitudinal median groove in frontal region; cervical groove dividing hepatic region from branchial ones; smooth dorsal carapace surface, except for some tubercles uniformly arranged in frontal region and in the outer parts of hepatic and epibranchial regions.
Etymology: after Zovo where the studied specimen was discovered.
Description: Subhexagonal carapace, convex longitudinally, broader than long (lcxp/wcxp = 0.45); orbito-frontal margin moderately wide (wof/wcxp = 0.38); bilobed front grooved medially and downturned; frontal margin with small tubercles arranged uniformly; small subround orbits with raised, granulate supraorbital margin; convex inner orbital angle well distinct from the front by an indentation; elongate, convex anterolateral margins, with two or three small spines, close each other, forming four short convex spiny lobes, divided by weak fissures: first with two small spines (excluding the extra-orbital tooth), second and third with three spines, and fourth, at level of anterolateral angle, with one spine and one granulate ridge (branchial ridge) extending on the branchial region; shorter posterolateral margins, strongly converging to the posterior margin; posterior margin as wide as the front, weakly convex and rimmed; undifferentiated dorsal regions; one deep longitudinal median groove in the frontal region; cervical groove dividing hepatic region from the branchial ones; weak transverse depression in the cardiac region; weak branchiocardiac grooves, more evident along the cardiac region margins; smooth dorsal carapace surface, except some tubercles uniformly arranged in the frontal region and in the outer parts of hepatic and epibranchial regions; small pits arranged uniformly on dorsal surface, richer in frontal and hepatic regions.
Discussion: Based upon Sakai (1976) and Serène (1984), the studied specimen shows the main morphological characters of the extant Neoliomera in having a carapace broader than long; anterolateral margins crested and entire, although marked with three to four demarcated, rounded lobes; and poorly defined regions. Neoli-omera is currently widely distributed in the Indo-West Pacific area with 17 species inhabiting rocky beach, under stones or in coral reef, and shallow waters (Ho & Ng, 2014).
Neoliomera is known in the fossil record of northern Italy with two species, N. paleogenica Beschin, Busulini, De Angeli & Tessier, 2007, from the early Eocene of contrada Gecchelina (Monte di Malo, Vicenza) and N. minuta Beschin, Busulini & Tessier, 2015 from the early Eocene of Cava Braggi (Vestenanova, Verona). The former differs from N. zovoensis sp. nov. in having meso-, metagastric, and cardiac regions that are well differentiated by grooves and thick tuberculate ornamentation uniformly arranged on the whole dorsal surface (Beschin et al., 2007). The latter differs from the new species in having a more oval carapace outline, dorsal surface of carapace with randomly arranged small tubercles, an anterior mesogastric process that does not reach the front, a carapace that is not marked by a cervical groove, an anterolateral margin with four smooth lobes, and an anterolateral angle without branchial ridge (Beschin et al., 2015).
Neoliomera zovoensis sp. nov. has a shallow cervical groove and a weak granulate ridge on the branchial regions, as in the extant N. themisto (De Man, 1889), widespread in the Persian Gulf (see Guinot, 1964). This extant species differs, however, from the fossil one in having more distinct hepatic and branchial regions with larger and more numerous tubercles.