New records of water mites from Chile (Acari: Hydrachnidia), with the description of three new species

Abstract. Three new species of water mites are described from Chile, viz. Pseudohydryphantes chilensis n. sp. (Hydryphantidae), Rhynchaturus dispar n. sp. and Rhynchaturus rucuensis n. sp. (Hygrobatidae). Andesobates magellanicus (Tuzovskij and Stolbov, 2016) is synonymized with A. longipalpis Smit, 2002. The first description is given of the females of Omartacarus ferradasae Cook and Rhynchaturus projectus Cook, and the male of Hygrobatella coriacea quiponensis Cook. Moreover, many new records are given, and two species are reported new for the fauna of Chile (not including the new species described in this paper).

The aim of this paper is to increase the knowledge of the water mites from Chile. Many new records are given, and three species are described new for science. Moreover, the unknown sex is described for three species.

Material and methods
The material described in this paper has been collected in December 2018 by using a dip net and kicksampling. Interstitial samples were taken by the socalled KaramanChappuis method. All material from this study is collected by the author, unless stated otherwise. Holotypes, paratypes and all nontype material will be lodged in Naturalis Biodiversity Center, Leiden (RMNH). The following abbreviations are used: a.s.l. -above sea level; CxI -first coxae; CxIV -fourth coxae; Cxgl4 -coxoglandularia 4; Dgl3 -dorsoglandularia 3; NP National Park; P15 -palp segments 15; IVleg2 -second segment of fourth leg. All measurements are in µm, measurements of palp and leg segments are of the dorsal margins, measurements of paratypes are given in parentheses. Ventral length is measured from the tip of CxI till posterior idiosoma margin. Numbers are given as male/female/deutonymph or adult/deutonymph. All coordinates are taken with a GPS. Coordinates given as degrees, minutes and seconds are taken from Google Earth and are by approximation. Data on the world distribution are taken from Smit (2020). Distributional data from Chile are taken from Besch (1964) and Cook (1988), those from Argentina from Cook (1980), unless stated otherwise. Pseudohydryphantes chilensis n. sp.  Diagnosis. Glandularia sclerites small, not crescent shaped; legs without swimming setae. Description. Male: Idiosoma reticulate with large papillae, dorsally 535 long and 348 wide, ventrally 559 long. Glandularia sclerites smaller than accompanying glandularia, rounded ( Figure 1A). Median eye and postocularia on small platelets, the latter more or less between Dgl3. Chelicera 211 long. Coxae in four groups, with few small setae; tip of CxI with two small, stout setae. Genital field with three pairs of acetabula, genital flap 164 long; along medial margin a row of small setae ( Figure 1B). Excretory pore sclerotized. Length of P15: 47, 72, 48, 96, 36. P2 and P3 with a medial seta and three and one dorsal setae, respectively. P4 with a stout dorsodistal setae ( Figure 1D). Length of Ileg46: 100, 120, 124. Length of IVleg46: 170, 180, 136. Legs without swimming setae ( Figure 1E). Claw of legs simple, without serrations or ventral clawlet, but with a small dorsal clawlet.

Taxonomy
Female: Unknown. Etymology. Named after the country of the type locality.
Remarks. This is the first Pseudohydryphantes species from South America. The new species differs from all known Pseudohydryphantes species in the absence of swimming setae. From North America two species are known, both insufficiently described by Marshall (1924Marshall ( , 1929. Main difference with the new species is the presence of swimming setae in the North American species.

Family Omartacaridae Cook
Genus Omartacarus Cook, 1963 Several species known from North, Central and SouthAmerica.
Remarks. The female matches the description of Cook (1988) well in the gnathosoma with a long rostrum and P4 with a short, stout seta.
Distribution. Thus far, known from the holotype male only from the interstitial of a stream near Lago Chapo, Llanquihue Province, Chile.

Ferradasia musicola
Remarks. The female of this study is not completely sclerotized, the dorsal platelets are not yet visible.
Distribution. Previously reported from a stream near Bariloche, Argentina (Cook 1980) and here reported for the first time from Chile.

Family Frontipodopsidae K. Viets
Genus Frontipodopis Walter, 1919 The genus occurs worldwide, most species of the subgenus Frontipodopsis are known from the southern hemisphere. Remarks. The genus Paratetrahygrobatella has been synonymized by Smit (2020) with Andesobates. However, also at the species level, there are no marked differences between A. longipalpis and A. magellanicus (males: both species with a large dorsal plate, CxIV large and more or less triangular, genital field with three pairs of widely separated acetabula). Therefore, I propose to synonymize the two species.

Genus Australiobates Lundblad, 1941
A genus with numerous species known from Australia, New Zealand, New Guinea, South Africa and South America (Smit 2020

Genus Brevaturus Schwoerbel, 1986
A genus with ten species known from Chile.
Brevaturus (Brevaturus) gonseri (Schwoerbel, 1986) (1164) wide, ventrally 1196 (1284) long. Dorsum in most aspects as in female, but postocularia separate from the large pairs of platelets, the latter 227 long. Moreover, the illustrated male has some irregularities, i.e., in one of the small glandularia platelets the glandularium is lacking and there is one unpaired rounded platelet ( Figure 3A). Venter as in female, apart from (red coloured) genital field. The latter is 235 long and 243 wide; gonopore 86 long. Genital field with numerous setae, posterior pair of acetabula larger than the two anterior pairs ( Figure 3B)

Genus Rhynchaturus Besch, 1964
A genus known from Argentina and Chile with eight species known thus far (Cook 1988; Tuzovskij & Stolbov 2017b.
Diagnosis. Dorsum with two pairs of lateral platelets and three pairs of medial platelets; idiosoma with distinct posterolateral tubercles; genital field with three pairs of acetabula.
Description. Female: Integument rugose, idiosoma dorsally 575 (591) long and 535 (543551) wide, ventrally 688 (705709) long, with a pair of large posterolateral glandularia tubercles. Dorsal shield with a pair of anteromedial platelets with the postocularia, a pair of posteromedial platelets each with a glandularium, a pair of large central platelets without glandularia and two pairs of lateral platelets, each with a glandularium ( Figure 4A). Dorsal projection of camerostome pointed, extending just beyond the tips of CxI. Gnathosomal bay Ushaped, with a short posterior cleft. Gnathosoma attached to a long protrusible tube. Suture lines of coxae indistinct. Between the coxae a chitinized area, interrupted by a narrow lineated nonchitinized area. Cxgl4 lying on CxIV. Genital field with three pairs of acetabula, the posterior pair partly lying under a sclerotized bar ( Figure 4B). Gonopore 188 long, genital field approximately 140 wide. Length of P15: 14, 50, 34, 60, 42. Palp stocky, especially P4 ( Figure  4C); P4 anteroventrally with two fine setae and one anteromedial seta. Length of Ileg46: 132,128,76. Length of IVleg46: 161,160,120. Leg claws with large dorsal and ventral clawlets, legs without swimming setae.
Male: Unknown. Etymology. The epithet dispar comes from the Latin, and means unlike or dissimilar (see below).
Remarks. The female of the new species lacks a pair of small platelets posterior to the pair of large central platelets. This pair of small platelets is present in all known females of the genus except for R. projectus Cook, 1988, described below. The female of R. projectus Cook, 1988 lacks also such a pair of small platelets, but this species has four pairs of acetabula instead of three pairs. Besch, 1964 New records. 0/1/0, small stream flowing into Lago Negro, Pumalín NP, prov. Rhynchaturus projectus Cook, 1988 ( Figure  Remarks. The female was unknown thus far, and is, therefore, described above. Distribution. Previously known only from the type locality in Valdivia Province, Chile.
Diagnosis. Male: Dorsal shield with a pair of small platelets posterior to the large central platelets, Cxgl4 lying in the posteromedial corner of CxIV, idiosoma with a pair of large posterolateral glandularia tubercles, genital field with three pairs of acetabula.
Description. Male: Integument less rugose compared to other species of the genus. Idiosoma dorsally 470 (454) long and 397 (413) wide, ventrally 559 (567) long. Dorsal shield with six paired platelets, the anteromedial pair with the postocularia, the posteromedial pair and the two lateral pairs each with a glandularium ( Figure 6A). The large central pair is 176 long and is without glandularia, as is the pair of small platelets posterior to the large central platelets. Dorsal projection of camerostome as long as CxI. Idiosoma with a pair of large posterolateral glandularia tubercles. Integument less rugose compared to other species of the genus. Gnathosomal bay Ushaped. Gnathosoma attached to a long protrusible tube. Area between the coxae chitinized. Cxgl4 in posteromedial corner of CxIV. Genital field with three pairs of acetabula. Gonopore occupying only a small area of genital field ( Figure 6B), 34 long; genital field 92 long and 120 wide. Length of P15: 12, 42, 34, 50, 34. Palp stocky, especially P4; P4 with two anteroventral fine setae, claws of P5 large ( Figure 6C). Length of Ileg46: 110, 102, 78. Length of IVleg46: 130, 162, 120. Leg claws with large ventral and dorsal clawlets, legs without swimming setae ( Figure 6D).
Female: Unknown. Etymology. Named after the type locality, the Rucue River.
Remarks. The species keys out with the key in Cook (1988) as R. circularis Cook, 1988, known in the female sex only. Females of the latter species have Cxgl4 lying in the middle of CxIV and the idiosoma shape is circular (more elongated in the new species). The position of Cxgl4 in the new species differs from all other species, which have these glandularia in the middle of CxIV. Cook, 1988 New record. 0/1/0, unnamed stream at Puente Zargazo, tributary of Río Chamiza, prov. Llanquihue, 41°28.717 ′ S 72°39.700 ′ W, 126 m a.s.l., 15 Dec. 2018. Remarks. The dorsal projection of the camerostome is irregularly shaped in the specimen of this study. The tip of the projection is bifid and also one of the lateral projections is bifid.

Rhynchaturus tricornis
Distribution. Previously known only from the type locality in Valdivia Province, Chile.
Genus Schizobates Thor, 1927 A monotypic genus, known from Argentina and Chile.

Subfamily Momoniinae K. Viets
Genus Notomomonia Cook, 1988 A genus restricted to Chile, with three species known.