492 Accepted by T. Wesener: 15 Sept. 2017; published: 14 Nov. 2017 ZOOTAXA ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) Copyright © 2017 Magnolia Press Zootaxa 4347 (3): 492–510 http://www.mapress.com/j/zt/ Article https://doi.org/10.11646/zootaxa.4347.3.4 http://zoobank.org/urn:lsid:zoobank.org:pub:2B3EE3EC-61C2-4071-AF10-BC3BD37ED2FF A new genus and species of Haplobainosomatidae (Diplopoda: Chordeumatida) from the MSS of the Sierra de Guadarrama National Park, central Spain JOSÉ D. GILGADO 1,2,5 , ENRIQUE LEDESMA 1 , HENRIK ENGHOFF 3 , JEAN-PAUL MAURIÈS 4 & VICENTE M. ORTUÑO 1 1 Research Team on Soil Biology and Subterranean Ecosystems. Department of Life Sciences. Faculty of Biology, Chemistry and Envi- ronmental Sciences. University of Alcalá (UAH). A.P. 20. Campus Universitario. E-28805, Alcalá de Henares, Madrid, Spain 2 Section of Conservation Biology, Department of Environmental Sciences, University of Basel. St. Johanns-Vorstadt 10, CH-4056, Basel, Switzerland. 3 Natural History Museum of Denmark (Zoological Museum), University of Copenhagen, Universitetsparken 15, DK-2100, København Ø, Denmark 4 Muséum National d’Histoire Naturelle, Dpt. Systématique et Evolution, 61 rue Buffon, F-75231 Paris Cedex 05, France 5 Corresponding author. E-mail: josedomingo.gilgado@uah.es Abstract The chordeumatidan fauna of the Iberian Peninsula is far from being well known, but recent efforts are improving that knowledge. Samplings carried out in the Milieu Souterrain Superficiel (also known as the Mesovoid Shallow Substratum) on several screes of the Sierra de Guadarrama National Park (central Spain) have led to the discovery of a new species of chordeumatidan millipede. This new species belongs to the family Haplobainosomatidae, which is mainly known from the northern Iberian Peninsula, and thus this is the first record of the family in central Spain. However, the extremely sim- ple gonopods of this species are so different from all other known species of the family that it must be placed in a new genus. In this work, a complete description of the species, named as Guadarramasoma ramosae gen. & sp. nov ., with a detailed iconography based on scanning electron microscopy images is provided together with a distribution map and a brief discussion of the implications of this new finding. Key words: Subterranean environments, orobiome, millipedes, Sierra de Guadarrama, new species Introduction Since Juberthie et al. (1980) first described the Milieu Souterrain Superficiel (MSS), many researchers have studied this peculiar environment (Mammola et al. 2016). The MSS consists of all the spaces formed by the network of fissures and interstices of the rocky debris and presents several special conditions, e.g., absence of light, high humidity throughout the year and attenuation of fluctuations of temperature and humidity compared to the surface (Giachino & Vailati 2010; Pipan et al. 2011; Jiménez-Valverde et al. 2015). The MSS may be formed by differing lithological processes in various types of rocks, giving rise to different types of MSS, such as volcanic, bedrock, colluvial or alluvial MSS (Juberthie et al. 1980, 1981; Oromí et al. 1986; Gers 1992; Juberthie 2000; Ortuño et al. 2013). The MSS is closely associated with the soil layers closest to the surface, allowing a relatively large flow of organic matter and energy, mainly from the surface to the subsoil (Gers 1998; Mammola et al. 2016). The fauna inhabiting the MSS is mainly constituted of arthropods (Rendoš et al. 2012; Ortuño et al. 2013; Jiménez- Valverde et al. 2015) and can be classified according to its level of specialization and adaptation to this habitat (Sket 2009). Thus, the MSS can harbour animals from the surface which come into this habitat searching for shelter during periods in which the external environmental conditions are adverse (Nitzu et al. 2010, 2014), but it can also harbour hypogean animals that permanently reside in this habitat. The fauna is stenoecious and hygrophilous with a high level of specialization and adaptation to its environment (Gers 1992; Ortuño & Toribio 1994; Hernando et al. 1999; Culver & Pipan 2008; Pipan et al. 2011).