A new species of Amblydromalus Chant & McMurtry (Acari: Phytoseiidae), with notes on occurrence of genus in South America

A new species, Amblydromalus amazonicus n. sp. is described and illustrated based on adults of both sexes. Individuals were found in association with plants in natural vegetation (Amazon Forest), on uncultivated plants in guarana crops, and on exotic fruit (residential area), in states of Amazonas and Mato Grosso, Brazil. The type material of A. akiri Nuvoloni, Lofego, Rezende and Feres was re-examined and the number of setae as well as the chaetotaxy of genu III is corrected. Notes on the occurrence of Amblydromalus in South America and a key to species of genus for this subcontinent is provided.

This study aims to describe a new species of the genus Amblydromalus, the first of its kind which presents J1 setae, associated with plants in the states of Amazonas and Mato Grosso, Brazil.

Material and methods
Mites were collected from leaf samples from six native plants and one exotic fruit (rambutan) in two states from Brazil (Amazonas and Mato Grosso). In the state of Amazonas, the samplings were carried out in municipalities of Itacoatiara, Maués, Parintins, and Silves (east region of the state). Natural vegetation and residential area were sampled in the first three municipalities and in the last, respectively. In the state Mato Grosso, the samplings were carried out in Cotriguaçu municipality (north region of the state) in natural vegetation. All areas are within the domain of the Amazon Forest biome.
The phytoseiid specimens were sorted under a stereomicroscope (40x) and subsequently mounted on microscope slides in Hoyer's medium. They were examined under phase-contrast microscopy (Zeiss Axio Imager M3). The new species was illustrated using a drawing tube attached to the microscope; the images were processed with the software Adobe Illustrator CS6. Measurements of taxonomically relevant structures were done with the use of a graded eye-piece. The measurements of the holotype (female) are given in bold, followed by the average measurement and then by minimum and maximum values (in parentheses) for the holotype and paratypes.
The setal nomenclature adopted was that of Lindquist and Evans (1965) and Lindquist (1994), as adapted by Rowell et al. (1978) for the dorsum and by Chant and Yoshida-Shaul (1991) for the venter of the phytoseiids. The idiosomal setal pattern follows Chant and Yoshida-Shaul (1992). The notation of gland pores (solenostomes) or lyrifissures (poroids) is based on Athias-Henriot (1975). Terminology for the spermathecal apparatus follows that described by Beard (2001).
The analyses on A. akiri were done studying specimens of the type series, deposited in the collection of Acari of the Departmento de Zoologia e Botânica, da UNESP, Campus de São José do Rio Preto, São Paulo, Brazil.
The studies that report the occurrence of Amblydromalus species in South America (previous records) were obtained from the Phytoseiidae Database  http://www.lea.esalq.usp.br/phytoseiidae/). Records of species of the genus that contained "cf." or "af." were not considered for this study. The records of A. horatii (De Leon) in Brazil, Guyana, and Suriname by Byrne et al. (1983) and Murphy (1984) were considered as Amblydromalus arawak (De Leon), since that this species is a junior synonym of A. arawak (Denmark et al. 1999).

Diagnosis
Female with dorsal shield smooth, only with some striae, mainly in anterolateral region; all dorsal setae smooth and pointed, except Z5 slightly serrated; with seta J1 present. Sternal shield smooth, except lateral striae, with posterior margin trilobate; genital and ventrianal shields smooth; ventrianal shield vase-shaped, with a pair of crescentic preanal pores; all ventral setae smooth. Calyx tubular; atrium widening next to major duct and with forked aspect; major duct with thick wall next to the atrium. Macrosetae smooth with knobbed tips, present on genua of all legs, tibiae of legs III and IV and basitarsus of leg IV.
Peritreme -Extending to level of j1. Spermatheca -( Figure 1C). Calyx tubular, 27 23 (18-27) (for some mounted specimens the calyx is visually bent); atrium widening next to major duct and with forked aspect; major duct with thick wall next to atrium.
Peritreme -Extending to level of z2. Chelicera -Fixed digit 20 long, with nine teeth in addition to hook and pilus dentilis; movable digit 17 long, with four teeth in addition to hook. Spermatodactyl ( Figure 1G)

Etymology
The specific name "amazonicus" refers to Amazon Forest biome.

Remarks
According to Chant and McMurtry (2005) mites of the genus Amblydromalus have the ratio s4: Z1> 3: 1. The ratio between these two setae in Amblydromalus amazonicus n. sp. was lower, being the type series average 2: 1 (2.2: 1 in the holotype; 1.8-2.4 in the type series specimens), what could lead this species to be classified as Ueckermannseius according to the definition of Chant and McMurtry (2007). However, the s4: Z1 < 3: 1 ratio has also been observed in other species classified as Amblydromalus: Amblydromalus tigrus ( Moraes et al. 1994). In addition, in other populations of two of these species, different from what was observed in the type series, was observed ratio greater than 3: 1 between s4 and Z1. In material collected from A. ntundu from Cameroon and DR Congo the ratio was 3.1: 1 ). In the case of A. manihoti, a species frequently collected in South America, the s4: Z1 ratio ranged from 1.8: 1 (Rocha et al. 2015) to 4.1: integrative taxonomy should be performed to verify the phylogenetic relationships within the Typhlodromalina subtribe, and verify if Amblydromalus and Ueckermannseius are in fact two valid clades or if constitute a single natural group.
Within Amblydromalus, only for a single specimen, collected in Cameroon, was reported the presence of seta J1. This specimen was identified as A. swaga (Pritchard & Baker) by Moraes et al. (2006), although for others four specimens analyzed in the same study, including holotype, the presence of J1 was not observed, indicating that the presence of this seta may be an anomaly in A. swaga. Differently in A. amazonicus n. sp. the presence of J1 is a stable character, present in all specimens found, including females, males and deutonymph. Amblydromalus amazonicus n. sp. belongs to the limonicus species group, by having Z4 much shorter than 40% of the distance between its base and that of seta Z5, and shorter than the distance between its base and that of seta S4 (Chant and McMurtry 2005). Despite the presence of seta J1 on dorsal shield we decided to include A. amazonicus n. sp. within the limonicus species group than creating a new one. Within of Euseiini tribe, the seta J1 is recorded in Typhlodromalus fragosoi (Yoshida-Shaul and Chant 1991).
Occurrences of Amblydromalus species in South America.
With the description of A. amazonicus n. sp., the genus currently has 24 described species.
Of these 13 are reported on the South American subcontinent (Table 1). All 13 species are registered in Brazil, five described in the last six years (Nuvoloni et al. 2015a, 2015b, Zannou et al. 2017. On the other hand, no species of this genus has been registered in Argentina, Chile and Uruguay. This difference in the number of records between countries is mainly due to the lack of surveys of mites in the countries. The last five described species of this genus were collected in regions hitherto little explored (Central-West, Northeast and North regions of Brazil). In addition, the records indicate a probable preference of these mites for regions of a warmer climate, which could explain the absence of these mites in regions further south of the continent.  (Garman & McGregor, 1956)