First record of the ant-loving cricket Myrmecophilus fuscus Stalling , 2013 ( Orthoptera : Myrmecophilidae ) in mainland Spain

Social insect nests are a rich source of biodiversity (Kistner, 1982). Arthropods are the main organisms inhabiting the galleries and spaces of ant nests (Passera & Aron, 2005). Antloving crickets are rarely observed and seldom collected, although we believe their occurrence in the field is greatly underestimated. Accordingly, myrmecologists and orthopterologists should collaborate to determine the distribution of these species and share knowledge and techniques. One ant-loving cricket species, Myrmecophilus fuscus Stalling, 2013, was recently described from Mallorca, Balearic Islands, Spain (Stalling, 2013) and was subsequently found in several countries within the Mediterranean Basin (Stalling, 2015). We present the first records of M. fuscus from the Spanish mainland. Two additional Myrmecophilus species are presently known in mainland Spain: Myrmecophilus acervorum (Panzer, [1799]) and Myrmecophilus ochraceus Fischer, 1853. Abstract We present the first published records of Myrmecophilus fuscus Stalling, 2013 from the Spanish mainland. We observed the species at various localities in Catalonia and in the city of Madrid. Six ant species are known hosts for M. fuscus in mainland Spain: Camponotus lateralis (Olivier, 1792), Crematogaster scutellaris (Olivier, 1792) and Formica cunicularia Latreille, 1798, as well as three ant species of the genus Lasius, two native and one exotic: L. grandis Forel, 1909, L. cinereus Seifert, 1992, and the invasive L. neglectus Van Loon, Boomsma & Andrásfalvy, 1990. Sociobiology An international journal on social insects


Introduction
Social insect nests are a rich source of biodiversity (Kistner, 1982).Arthropods are the main organisms inhabiting the galleries and spaces of ant nests (Passera & Aron, 2005).Antloving crickets are rarely observed and seldom collected, although we believe their occurrence in the field is greatly underestimated.Accordingly, myrmecologists and orthopterologists should collaborate to determine the distribution of these species and share knowledge and techniques.

Materials and Methods
During routine myrmecological surveys, ant nests located beneath stones were checked for ant-loving crickets by Xavier Espadaler and Nilo Ortiz de Zugasti Carrón.All Myrmecophilus specimens were caught, preserved in ethanol, and subsequently pinned and dried.Additional specimens collected by Hervé Brustel were examined.Most of the records from previous years from the Barcelona region were published as M. acervorum (Panzer, [1799]) by Espadaler and Olmo-Vidal, (2011) and the specimens were re-examined in 2015, after the description of M. fuscus.
Specimen identification was performed according to the criteria of Stalling (2013) and by direct comparison with specimens of the type series of M. fuscus.The species differs from other Myrmecophilus species in Spain by the following characteristics: the coloration is dark ochreous with pale ochreous posterior margins of the pronotum, mesonotum

We detected
Spain, Madrid (all leg.N. Ortiz de Zugasti Carrón): Madrid, 40°25'40.7"N, 003°43'54.1"W, 590 m.a.s.l., 25.vii.2014, 3 ad.males, 2 ad.females (Fig 2 ), 2 female nymphs and 3 nymphs of unknown sex in nest of Lasius grandis.Madrid, 40°26'17.0"N, 3°43'29.28"W, 641 m.a.s.l., 03.vii.2015. 2 adult females, 1 adult male and 8 nymphs in a nest of L. grandis.The first nest, observed in 2014, was established under a small concrete slab of 60 × 60 × 6 cm.The location is watered periodically, although the irrigation frequency has greatly diminished over the past few years owing to drought in the Madrid region, resulting in a loss of the green lawn that surrounded the nest.However, all of the trees in the area remain.The slab is located underneath three cypress trees where the ants actively forage as well as a fruit tree (Prunus sp.), and is in proximity to Robinia pseudoacacia.Despite the dry and dusty surrounding ground, there is sufficient atmospheric humidity owing to the Manzanares River, which is within approximately 25 m (with a phreatic level of about -3 m underground).Some cricket nymphs were found (but not collected) in other L. grandis nests (under typical rocks) within 300 m of this nest.The second nest, detected in 2015, was established under a similar concrete slab in a permanently watered lawn with abundant poplar trees; this site is located within the terrain of the Principalship buildings of Complutense University.Some nymphs were also detected (July, 2015) under rocks along the artificial stream of the "Parque del Oeste" (Western Park), within 500 m of the second location and also in permanently watered lawn.

Discussion
We recorded Myrmecophilus fuscus on the Spanish mainland.Prior to its description in 2013, the species was not distinguished from M. acervorum and some specimens were therefore erroneously identified as M. acervorum (Espadaler & Olmo-Vidal, 2011).M. acervorum is also found in the Barcelona region.The observation of the species in Madrid greatly extends the known range of M. fuscus in Spain.We detected the crickets on both banks of the Manzanares River at sites separated by a distance of 3 km.The presence of the species in artificially watered gardens indicates a possible accidental introduction.
Camponotus lateralis, Crematogaster scutellaris and Formica cunicularia, as well as three Lasius species, two native and one exotic, are known hosts for M. fuscus in mainland Spain.L. grandis "… is the most abundant species of the subgenus on the Iberian peninsula…" (Seifert, 1982) and L. cinereus is common in eastern Spain (Espadaler et al., 2011).The invasive L. neglectus in Iberia is restricted to limited localities in Catalonia and the Basque country.Camponotus lateralis, Crematogaster scutellaris and Formica cunicularia are widely present in the Mediterranean region, with continuous distribution across the Iberian Peninsula (Gómez & Espadaler, 2007).Accordingly, M. fuscus could be expected to occur in the wide area between Madrid and Barcelona.Portugal is a candidate country for M. fuscus based on the presence of known ant hosts in the country.
Myrmecophilus fuscus at the following localities (Fig 1, all specimens in coll.T. Stalling).

Fig 1 .
Fig 1. Distribution of Myrmecophilus fuscus in Spain.Black dots: new records from the Spanish mainland; white dot: locus typicus published by Stalling (2013).The map is based on a map from Виктор, © Creative Commons License.