Water mites from Fuerteventura, Canary Islands, Spain (Acari: Hydrachnidia)

The first records are presented of water mites from Fuerteventura, Canary Islands. Five species were found, three of which are widespread in the (SW) Palaearctis. One species new to science is described, Neumania fortiventa while Arrenurus pervius Walter is synonymized with A. caesaraugustanus Viets, a rare species only known from temporary and/or saline ponds in semiarid climate.


Introduction
Several publications are known of the water mites of the Canary Islands.Lundblad (1962) reported water mites from La Gomera, Gran Canaria, La Palma and Tenerife.Later on, Lundblad (1972) published more records of Gomera.K.O.Viets (1968) published new records of water mites from La Gomera and La Palma, Gerecke (1999) published one species new to science from La Gomera and Valdecasas (2002) added more records from La Palma.Finally, Zawal & Pešić (2015) published the first record of the marine water mite Litarachna duboscqi Walter, 1925 from Tenerife.In this paper data are presented from Fuerteventura.This island has a desert-like climate, with a mean rainfall of only some 100 mm/year, while the temperature ranges from 20 º -27 º C. Most rain falls in the winter months, especially in December.Surface water is very scarce, and occurs as temporary pools, man-made reservoirs, springs and a few temporary streams.

Material and Methods
All localities were found with the help of a map (scale 1: 50.000;Kompass, Innsbruck).Except for the springs called Fuente Blanca S of Puertito de los Molinos and Fuente del Chupadero (NW of La Mantilla), all springs mentioned on this map were visited, but the following sites could not be found: Fuente de las Tenerías and Fuente del Chupadera (both SW of Tindaya), Fuente del Viso (E of La Asomada), Fuente de Majada Larga and Fuente de la Breña (N of Casillas del Angel).The following springs were without water mites: Fuente Cochina de Tao and Fuente de Tabalba.Three streams were visited, all without water mites: Ecologica Montenegrina 11: 14-19 (2017) This journal is available online at: www.biotaxa.org/emRio Cabras, Rio Palmas and a small stream N of Pájara crossing road PV-30.Two reservoirs were without water mites: Embalse de los Molinos and Presa de las Peñitas.Abbreviations used: Asl = above sea level; P1-5 = palp segments 1-5; I-leg-4-6: segments 4-6 of first leg.Measurements are given in µm.Diagnosis.Integument with very small spines, genital field rounded, gonopore narrowed anteriorly.
Etymology.The name is derived from Fuerteventura, which means strong winds.Walter, 1927(syn.: Neumania atlantida Lundblad, 1941, Pešić et al. 2007) thus far the only known Neumania species from the Canary Islands, in the shape of the male genital field.The latter species has a genital field with somewhat angular lateral corners, and the narrowing of the gonopore is lacking.Moreover, P4 of the new species is more stocky, and the new species is much larger than N. atlantida, which measures 550 in idiosoma length.None of the European species with an integument with spines has a similar shape of the gonopore and genital field.Neumania seurati Walter, 1931 from southern Algeria has a similarly shaped genital field, but lacks the narrowing of the gonopore.Moreover, the palp is more slender compared with the new species.

Remarks. The new species differs from Neumania uncinata
Family Arrenuridae Thor, 1900
Remarks.The colour of the idiosoma in Western Europa is reddish-brown, but the specimens from Fuerteventura are yellowish.Arrenurus radiatus is widespread in the Palaearctis.Description.Male: Idiosoma 894-965 long and 664-737 wide.Dorsal shield somewhat elongated, dorsal furrow in two males complete, in two other males (both fully sclerotized) incomplete (fig.2A).Petiole hyaline, tube-like, dorsal margin with a broad tooth (fig.2B).Female: The female matches the description given by Viets (1930), but there is a remarkable range in size: length 794-1166, width 648-925.

Arrenurus (Micruracarus) caesaraugustanus
Remarks. Walter (1940) described A. pervius from Algeria, but his description matches the description of A. caesaraugustanus from Zaragoza Province, northern Spain given by Viets (1930) and he does not discuss diagnostic differences between the two species.The figure of the male posterior idiosoma of Walter is very sketchy, but in the description he mentioned the hyaline tube-like petiole with a small tooth in the middle of the dorsal margin (as given in Fig. 2B).Moreover, the size of A. pervius is in agreement with A. caesaraugustanus: Male L 900, W 750, female L 1140, W 945. Palp measurements of Viets (1930) of A. caesaraugustanus must be erroneous, as they are two times as large as the specimens from Fuerteventura.When we take this into consideration, palp measurents of the two species are similar.The only difference is the number of setae on the medial margin of P2, seven in A. caesaraugustanus and four in A. pervius.However, the female of A. caesaraugustanus has P2 with four setae only.Therefore I propose to synonymize A. pervius with A. caesaraugustanus.The species is known only from Spain, Algeria and Fuerteventura.All localities where the species has been found are either temporary or somewhat saline.