Levantoniscus, Cardoso, Giovanna Monticelli, Taiti, Stefano & Sfenthourakis, Spyros, 2015

Cardoso, Giovanna Monticelli, Taiti, Stefano & Sfenthourakis, Spyros, 2015, A new genus of Trachelipodidae Strouhal, 1953 (Crustacea, Isopoda, Oniscidea) from the eastern Mediterranean, Zootaxa 4040 (1), pp. 1-16 : 2-3

Genus Levantoniscus n. gen.

Type species: Levantoniscus bicostulatus n. sp., here designated; gender masculine.

Diagnosis. Oval body shape, outline not interrupted between pereon and pleon. Body with conspicuous lamellar or acute dorsal tubercles covered with piliform setae. One line of noduli laterales inserted far from lateral margins of pereonites 1–4 and near posterolateral corners on pereonites 5–7; no gland pores on pereon epimera. Head with prominent frontal lateral and middle lobes. Eyes reduced to five or less ommatidia. Pereonite 1 with posterior margin concave at sides. Pereon epimera and pleon epimera 3–5 quadrangular. Telson hourglass-shaped, with more or less concave posterior margin. Mandibles with dichotomized molar penicils. Outer branch of maxillula with teeth apically entire. Pereopods with dactylar and ungual setae flagelliform. Pleopod 2–5 exopodites interlocking, with deep groove on medial and proximal margin to receive distal part of previous pleopod exopodites. Pleopod exopodites with uncovered lungs, consisting of ridges and folds on dorsal surface of pleopod 1 and 2 exopodites, and in invaginations on pleopod 3–5 exopodites.

Etymology. The name of the genus refers to the Levant Region, where the species occur + oniscus.

Remarks. The family Trachelipodidae has six genera ( Schmalfuss 2003; Taiti & Ferrara 2004): Trachelipus Budde-Lund, 1908 , Porcellium Dahl, 1916 , Pagana Budde-Lund, 1908 , Nagurus Holthuis, 1949 , Panchaia Taiti & Ferrara, 2004 , and Tamarida Taiti & Ferrara, 2004 . The new genus is included in Trachelipodidae as it has a twosegmented antennal flagellum and uncovered lungs on all pleopod exopodites. Levantoniscus differs from all the other genera in the family in having distinct dorsal ornamentation, interlocking pleopods and different morphology of lungs on pleopods 3–5, i.e. with the respiratory surface inside invaginations of the exopodites. These characters are unique in the family Trachelipodidae and certainly derived since the plesiomorphic states present in lower taxa are: smooth dorsum, pleopods overlapping and not interlocking, uncovered lungs with respiratory surface mostly exposed and not included in invaginations. These characters can be considered as autapomorphies of the new genus.

Levantoniscus includes the two new species from Cyprus described below and L. wahrmani ( Strouhal, 1968) from Israel and the Hatay region of southeastern Turkey which was originally assigned to the genus Bathytropa . As pointed out by Schmidt (2003) in his attempt to re-define the family Bathytropidae , the monophyly of the genus Bathytropa was questioned by the inclusion of this species since, according to the original description by Strouhal (1968), it has lungs or respiratory fields of Trachelipus - type in the exopodites of pleopods 1–5. Moreover, this species has an hourglass-shaped telson and interlocking pleopod exopodites which are not present in any of the other 10 species of Bathytropa (for bibliographic references of this genus see Schmalfuss 2003 and Taiti & Rossano 2015). The transfer of this species to the new genus restores the purported monophyly of Bathytropa .

According to our knowledge interlocking pleopod exopodites are present only in species of Stenoniscidae (see Vandel 1962; Taiti & Ferrara 1982) and three genera of Armadillidae from Australia ( Buddelundia Michaelsen, 1912 , Barrowdillo Dalens, 1993 , and Stigmops Lillemet & Wilson, 2002 ) (see Dalens 1992, 1993; Lillemet & Wilson 2002; Taiti 2014). This derived character in phylogenetically distant families suggests that its presence is due to convergence.

In Levantoniscus the lungs on the exopodites of pleopods 1 and 2 are typically uncovered, i.e. consisting of ridges and folds with the respiratory surface almost entirely exposed like in the genus Trachelipus Budde-Lund, 1908 (Trachelipodidae) (see Hoese 1982; Schmidt & Wägele 2001), in the genus Atracheodillo Arcangeli, 1950 (Eubelidae) (see Paoli et al. 2002) or in the genus Sinodillo Kwon & Taiti, 1993 (Armadillidae) (see Kwon & Taiti 1993; Taiti et al. 1998). The lungs on exopodites of pleopods 3–5 have the same structure of ridges and folds but the respiratory surface is allocated inside an invagination near the lateral margin of the exopodites and not visible in dorsal view. This special kind of lung can still be considered as uncovered due to the same kind of respiratory surface. Its position inside an invagination, instead of being exposed as in all the other species of Trachelipodidae , could be due to the interlocking structure of the pleopods.

As pointed out by Schmidt (2003: 131) the phylogenetic relationships within the family Trachelipodidae , but also with related taxa (e.g., Agnaridae , Porcellionidae , Cylisticidae etc.), still remain unclear and should be examined also by means of molecular analyses.