## 1 Introduction  
Finger lime (_Citrus australasia_ F. [PERSON]) is one of six _Citrus_ species endemic to Australia. Its native range is mainly restricted to the rainforests of Queensland and New South Wales [1]. Compared with other citrus fruit, finger lime is probably one of the most attractive and interesting, especially for its high levels of natural genetic diversity. The tree can reach up to 6 m in height and the fruit presents a finger-like shape, characterized by a wide range of colors of pulp and peel, including purple, green, yellow, and pink) [1]. Finger lime is also called cavidar lime, as one of the most distinctive traits of the fruit is the spherical pulp sacs which give the pulp a cavidar-like appearance (Figure 1) [1,2]. Some native fruits were selected to be commercially cultivated only in the 1990s and afterward, some Australian endemic varieties were considered for commercial production [3]. Finger lime can adapt to the unusual soil and different climate conditions found in Australia, from extreme drought to rainforest [3]. As a result, they have many agronomical traits of potential interest, including tolerance to drought, reduced fruiting period, resistance to diseases, and a unique genetic diversity [3]. Because of its appealing colors and unique organoleptic and flavor characteristics, in Australia, finger limes are generally eaten fresh in fruit salads, while the pulp is also used in gourmet food to garnish seafood (oyster, caviar, and sushi), or added in alcoholic drinks. Currently, global interest is increasing in finger lime and cultivar (CV) breeding programs and/or trial plantations have been developed both in the United States and China [1]. Interest has also been garnered in the use of this fruit in industrial applications [3]. The content of complex polyphenols contributes to the variability of colors among the varieties and the antioxidant properties reported for the finger lime species. For instance, the investigation of four CVs in Florida highlights the occurrence of flavonoids, anthocyanins, vitamin C, citric acid, and sugars characterized by antioxidant capacity at higher levels in the peel compared to the pulp in the four selections [4]. The occurrence of phenolic compounds is related to potential health-promoting effects supporting the nutraceutical use of fruits. Finger lime extracts inhibited in vitro the NO-releasing and the inflammation-related cytokines and alleviated LPS-induced upregulation of several patterns [2]. In general, _Cirrus_ species have a very peculiar and attractive aroma, which makes them particularly agreeable. Finger lime aroma and flavor are highly variable. However, the peel of this fruit is frequently defined as having an intense floral lime aroma, while the juice as being sour and relatively strongly pungent [3]. Odor perception is strictly related to the presence of volatile organic compounds (VOCs). To date, analyses of the volatiles in the peel oil of commercially-grown Australian finger limes are limited [1]. [PERSON] et al. (1993) described that the volatile content of a cold-pressed oil of \"Faustrime\", a trigeneric hybrid of _M. australasiax \(\times\) Fortunella_ sp. \(\times\)_C. aurantifolia_, cultivated in Italy, was dominated by limonene (43.2%), citronellal (16.3%) \(\gamma\)-terpinene (4.5%), and \(\alpha\)-phellandrene (4.5%) [5]. The VOCs composition of the essential oil of the peel of _C. australasiax_ var. Sanguinea adapted in Sicily was evaluated by [PERSON] et al. (2000) by a GC-MS analysis which allowed to identify, as principal constituents, bicyclogermacrene (26%), \(\alpha\)-pinene (10%), spathulenol (10%), and _cis_-\(\beta\)-ocimene (5.1%), whereas limonene was detected as only 1.2% of the total oil [6]. A few years later, [PERSON] et al. (2002) compared the VOCs pattern of the peel and leaf oil of 43 lemons and limes produced in Corsica, showing that the lime species could be clustered into three chemotypes:  
Figure 1: Typical finger lime fruit.