A new littoral interstitial species of the genus Isotomodes (Collembola, Isotomidae) from Italy.

The genus Isotomodes Linnaniemi, 1907 can be easily recognized among Isotomidae because of its remarkable morphology and chaetotaxy of the last abdominal segments (Gama, 1963; Potapov, 2001); it comprises 34 worldwide species (Bellinger et al. 2014, Potapov 2001, Arbea 2006, Abrantes & Mendonça 2007, Thibaud 2008) mainly distributed in Europe (especially in Mediterranean region) and America, and only a few from est Asia and Oceania (Bellinger et al. 2014). The genus Isotomodes appears well represented in interstitial sandy habitat, especially in supralittoral and inland biotopes, as reported by Thibaud & Christian (1997) and Thibaud (2007). The littoral fauna of Collembola along the Italian peninsula has been poorly studied (Dallai et al. 2010), so we decided to fill this gap beginning with a collecting design along the Thirrenian coast of Tuscany. As preliminary result, herein we describe a new species of Isotomodes that had been collected in the sand dune in front of the Regional Park of S. Rossore (Tuscany). The material was collected on the sand dune in the Park of S.Rossore (Tuscany, central Italy) using a corer (volume 500 ml). Several soil samples were collected and the mesofauna was recovered by means of Berlese funnels. Sorting and recovering of the species through a stereoscopic microscope. Specimens of Isotomodes tyrrhenicus sp. nov. were mounted on slides both in lactic acid and Marc Andrè fluid; we described the new species following the terminology as proposed by Gama (1963), Potapov (2001) and Fjellberg (1999). For scanning electron microscopy, specimens preserved in 80% ethanol were completely dehydrated in absolute ethanol, critical-point dried in a Balzer CPD 030 apparatus and coated with gold in a Balzer MED 010 sputter coater. Observations were performed with a Philips XL20 scanning electron microscope. Abbreviations used in the text: Th.––thoracic tergum, Abd.––abdominal tergum, Ant.––antennal segment, PAO––postantennal sense organ, VT––ventral tube.