A new record of an Arrenoseius Wainstein species and a new species of ChelaseiusMuma & Denmark (Mesostigmata: Phytoseiidae) from Brazil

In an effort to understand the fauna of Gamasina (Mesostigmata) edaphic mites from Brazil, Arrenoseius robertogonzalezi Trincado & Martin, 2018, known only from the original description from Chile, was found. Complementary morphological information is provided for this species . Likewise, a new species, Chelaseius pluridentatus n. sp. was found and is here described; it is distinguished from other Chelaseius Muma & Denmark species mainly by having more teeth on the fixed cheliceral digit, seven instead of 2–5. A key to the world species of Chelaseius is also provided.


Introduction
Phytoseiidae (Mesostigmata: Gamasina) is the most extensively studied family of predatory mites (McMurtry et al. 2015). These are mostly found on plants, although some species are less commonly found in the soil. Some species of this family are broadly used for the biological control of pests, especially mites and small insects (McMurtry et al. 2015; Knapp et al. 2018. About 2,560 valid species are presently placed in this family, divided into three subfamilies, namely Amblyseiinae, Phytoseiinae and Typhlodrominae (Moraes et al. 2004; Demite et al. 2023.
In an effort to understand the fauna of Gamasina edaphic mites from Brazil, the aim of the study is to provide a new record of Arrenoseius and to describe a new species of Chelaseius, providing a key to world species of the latter genus.

Material and methods
Samples of litter/soil were collected in areas of the Brazilian states of Rio Grande do Sul (Pampa biome) and São Paulo (Atlantic Forest biome). In the laboratory, mites were extracted from the samples in a modified Berlese-Tullgren apparatus (Oliveira et al. 2001). All mites were mounted in Hoyer's medium for later examination under phase contrast (Leica, DMLB) and differential interference contrast (Nikon, Eclipse 80i) microscopes. The Mesostigmata were separated into families, based on Lindquist et al. (2009), and the Phytoseiidae were separated into genera, based on Chant and McMurtry (2007). The Arrenoseius and the Chelaseius specimens were compared with the original descriptions and redescriptions of the species presently affiliated to these genera.
Complementary information on the morphology of the Arrenoseius species collected is provided, based on the collected voucher specimens. The Chelaseius species was found to belong to a new species, herein described. Measurements were taken with a graded ocular attached to the phase contrast microscope. For each character, the average measurement is given first, followed (in parentheses) by the respective range, all in micrometers. Shield lengths were taken along the midline from the anterior to the posterior margins, and the width, at the widest level, except where otherwise specified.
The most relevant taxonomic structures of the new species were photographed using a digital camera connected to the differential interference contrast microscope. Illustrations were made using Adobe Illustrator®. Dorsal setal nomenclature is based on Lindquist and Evans (1965), as adapted by Rowell et al. (1978); ventral nomenclature is based on Chant and Yoshida-Shaul (1991); idiosomal setal pattern, on Chant and Yoshida-Shaul (1992); and notation of pore-like structures, on Athias-Henriot (1971, 1975. The key provided for the separation of the Chelaseius species was prepared based on the original descriptions and available redescriptions. The species included were those whose adult females have been described and that were reported in Demite et al. (2023). In the key, only the country of original description is mentioned.

Adult male
Not known.

Etymology
The name pluridentatus refers to the presence of more teeth on the fixed cheliceral digit of this species than in other Chelaseius species.

Remarks
Chelaseius pluridentatus n. sp. differs from other known Chelaseius species by having seven teeth (instead of 2-5 in other species, according to Denmark & Kolodochka, 1990; Chant & McMurtry, 2004. It is most similar to C. austrellus (Athias-Henriot, 1967), but females of the latter have setae J5, Z4 and Z5 barbed, seta s4 about eight times as long as z4; seta Z4 about 12 times as long as S4; and calyx of spermatheca about 20 long. It is similar to C. braziliensis Denmark & Kolodochka, concerning the higher number of teeth on the fixed cheliceral digit (five teeth in C. brazilensis, lower number in other species) and an ellipsoid tubercle at the base of the pilus dentilis (this feature may not have been given full attention in the description or redescription of some other species), but the latter differs by having spermathecal calyx cup-shaped.  (Chant & Hansell, 1971); Canada