A new Discidae subgenus and two new species (Gastropoda: Pulmonata) from the Canary Islands

Abstract

The family Discidae has undergone extensive speciation in the Macaronesian region (eastern Atlantic Ocean), with 11 endemic species recognised from Madeira and the Canary Islands in recent checklists (Bank, Groh & Ripken 2002; Seddon 2008; Fauna Europaea database project 2011), grouped into the genera Keraea Gude, 1911 and Discus Fitzinger, 1833: K. deflorata (R.T. Lowe, 1855) and D. (Atlantica) guerinianus (R.T. Lowe, 1852), from Madeira; and nine species from the Canary Islands: K. garachicoensis (Wollaston, 1878), D. scutula, (Shuttleworth, 1852), D. engonatus (Shuttleworth, 1852), D. textilis (Shuttleworth, 1852), D. retextus, (Shuttleworth, 1852), D. putrescens (R.T. Lowe, 1861), D. ganodus (J. Mabille, 1882), D. gomerensis Rähle, 1994, and D. kompsus (J. Mabille, 1883). In contrast with the anatomical data known for the European and North American genera Discus and Anguispira Morse, 1864 (Uminski 1962; Pilsbry 1948), there has hitherto been no information published on the internal anatomy of the Canary Islands and Madeiran species, which are known only by their shell characters. In this paper we raise Atlantica to the rank of genus in the Discidae and describe shell and anatomical characters for two new species from La Gomera and Tenerife, respectively. They are grouped in a new subgenus of Atlantica, largely restricted to the laurisilva. This laurel-rich forest occurs in humid subtropical and warm-temperate regions with little variability in temperatures and is developed between 600 and 1,200 m above sea level in the Canary Islands (Yanes et al. 2009b: Fig. 2).