Cheiroseius xerophilus De Moraes 2017, n. sp.

Cheiroseius xerophilus n. sp.

Diagnosis (Female): Dorsal shield ornate with a network of ridges and depressions; podonotal region of dorsal shield with 21 pairs of setae; opisthonotal region with 15 pairs of setae. Unsclerotised cuticle along margin of dorsal shield with four pairs of setae; pre-sternal area without platelets; Ventrianal shield subtriangular, reticulate over nearly its entire surface, with three pairs of setae in addition to circumanal setae; all legs with pretarsi and claws. Median section of pulvilli of legs II–IV as well as paradactyli of these legs acuminate.

Material examined. Holotype female and nine paratype females from litter at the base of Mimosa sp. (Fabaceae) at Olho D’água das Flores (09°31'33'' S, 73°16'46" W), State of Alagoas, Brazil; collected by J.C. Santos on August 23, 2012; deposited at Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, State of São Paulo, Brazil.

Adult female (Figs 14–24) (nine specimens measured).

Gnathosoma. Antiaxial and dorsal lyrifissures as well as dorsal seta distinct; fixed cheliceral digit 44 (39–46) long, with six teeth in addition to apical tooth and a setiform pilus dentilis; movable cheliceral digit 42 (41–42) long, with two teeth in addition to apical tooth (Fig. 14). Palp setae (trochanter to tibia): 2–5–6–13; setae aciculate and smooth, except al 1 and al 2 of palp genu spatulate and smooth (Fig. 15); seta v 2 of palp trochanter elongate (Fig. 17). Anterior region of epistome with three extensions, each with 2–4 points, the median longer than others (Fig. 16). Deutosternal region not delimited by lateral lines, with seven transverse rows of teeth about parallel to each other, each bearing 7–17 small teeth; corniculus horn-like, reaching nearly mid-level of palp femur; setae h 2 inserted slightly posteriad of h 3 (Fig. 17). Measurements of setae: h 1 41 (39–42), h 2 15 (14–17), h 3 24 (22–27), pc 27 (25–30).

Dorsal idiosoma (Fig. 18). Idiosoma 436 (403–450) long and 286 (283–300) wide at widest point. Podonotal and opisthonotal shields fused, completely covering idiosoma and extending to the ventrolateral region, with a network of ridges and depressions. Podonotal region with 21 pairs of setae (j 1– j 6, z 1– z 6, s 1– s 6 and r 2– r 4) and three pairs of distinguishable pores. Opisthonotal region with 15 pairs of setae (J 1– J 5, Z 1– Z 5, S 1– S 5), two pairs of distinguishable lyrifissures and two pairs of distinguishable pores. Unsclerotised cuticle along lateral margins of opisthonotal region with four pairs of setae (r6, R 1, R 3 and R 4). Measurements of setae: j 1 30 (30–31), j 2 46 (45– 48), j 3 45 (44–45), j 4 45 (44–48), j 5 46 (45–47), j 6 47 (45–49), J 1 40 (40–41), J 2 48 (47–50), J 3 46 (45–46), J 4 50 (50–51), J 5 13 (12–15), z 1 30 (30–31), z 2 42 (40–43), z 3 44 (42–46), z 4 41 (40–43), z 5 30 (30–21), z 6 46 (45–47), Z 1 44 (41–47), Z 2 50 (48–51), Z 3 51 (50–52), Z 4 52 (51–53), Z 5 60 (60–62), s 1 32 (31–32), s 2 41 (40–42), s 3 41 (40–44), s 4 46 (44–47), s 5 46 (45–50), s 6 54 (50–57), S 1 57 (55–60), S 2 51 (50–55), S 3 54 (52–55), S 4 55 (53–60), S 5 60 (58–60), r 2 31 (30–32), r 3 37 (35–40), r 4 50 (49–50), r 6 26 (24–30), R 1 16 (16–17), R 3 19 (19–20), R 4 21 (19–23). Dorsal idiosomal setae inserted on tubercles and about as long as or slightly longer than distance to subsequently setae of the same series; setae smooth, except J 5 (pilose) (Fig. 19).

Ventral idiosoma (Fig. 20). Base of tritosternum 16 (16–17) long and 11 (11–12) wide proximally (Fig. 21); laciniae 107 (105–110) long, separated for about 60% of their total length, pilose along distal half. Pre-sternal area without platelets. Sternal shield 81 (80–82) long at mid-line and 95 (94–95) wide between the setae st 1 and st 2; striate laterally, smooth elsewhere; posterior margin slightly concave; with three pairs of setae and two pairs of lyrifissures; with prominent endopodal projections between coxae I and II. Third pair of sternal lyrifissures and sternal setae st 4 on metasternal plates. Genital shield smooth, posterior margin truncate, apex of hyaline anterior margin rounded, overlapping posterior margin of sternal shield; distance between st 5– st 5 51 (50–54). Unsclerotised cuticle with a pair of lyrifissure (iv 5) posterolaterad of st 5; pore gv 2 inserted on peritrematic plate behind of coxa IV. One pair of elliptical metapodal plates. Ventrianal shield subtriangular, reticulate over nearly entire surface, 123 (113–132) long at mid-line and 172 (165–180) wide at widest level; with three pairs of setae (Jv 2, Jv 3 and Zv 2) in addition to circumanal setae, all smooth and sharp pointed; para-anal and post-anal setae similar in length, para-anal seta inserted slightly posteriad of posterior margin of anal opening; with one pair of marginal pores near Jv5. With two or five elongated platelets between genital and ventrianal shields. Six pairs of opisthogastric setae on unsclerotised cuticle flanking ventrianal shield (Jv 1, Jv 4, Jv 5, Zv 1, Zv 3 and Zv 5). Peritreme broad and elongate, extending posteriorly beyond stigma and curved inward behind coxa IV. Exopodal plate consolidated with peritrematic plate; whit two pairs of lyrifissures and two pairs of pore posteriad of stigma. Measurements of setae: st 1 19 (18–20), st 2 17 (16–18), st 3 17 (16–19), st 4 16 (15–17), st 5 16 (15–18); Jv 1 16 (15– 18), Jv 2 21 (20–23), Jv 3 28 (27–30), Jv 4 27 (25–30), Jv 5 31 (30–32), Zv 1 13 (12–15), Zv 2 19 (17–20), Zv 3 17 (17– 18), Zv 5 23 (20–27); para-anal 15 (14–15), post-anal 16 (15–18).

Peritreme and peritrematic plate. Peritreme broad and elongate, extending anteriorly to the level of j 1; anterior region not visible dorsally, posteriorly beyond behind stigma and curved inward coxa IV. Exopodal plate consolidated with the peritrematic plate. Peritrematic plate fused with the dorsal shield anterior to r 2, posteriorly behind coxa IV; with a pair of distinguishable lyrifissures and a pair of pores behind the stigma (Fig. 20).

Spermathecal apparatus. (Fig. 22) Calyx apparently dish-shaped; major duct distinct; sperm induction pore apparently on anterior margin of coxa IV; minor duct also distinct; atrium aparently horseshoe shaped.

Legs. All legs with pretarsi and claws. Median section of pulvilli of legs II–IV as well as paradactyli of these legs acuminate (Fig. 23). Lengths: I: 357 (355–360); II: 299 (280–310); III: 297 (260–300); IV: 395 (380–410); tarsus I: 111 (105–115), tibiae I: 63 (60–65). Chaetotaxy/setation – coxae: I: 0, 0/1, 0/1, 0; II: 0, 0/1, 0/1, 0; III: 0, 0/ 1, 0/1, 0; IV: 0, 0/1, 0/0, 0; trochanters: I: 1, 0/1,1/2, 1; II: 1, 0/1, 1/2, 0; III: 1, 1/2, 0/1, 0; IV: 1, 1/1, 0/2, 0; femora: I: 2, 3/1, 2/2, 1; II: 2, 3/1, 2/1, 1; III: 1, 2/1, 1/0, 1: IV: 1, 2/1, 1/0, 1; genua: I: 2, 3/2, 3/1, 2; II: 2, 3/1, 2/0, 2; III: 2, 2/1, 2/0, 1; IV: 2, 2/1, 3/0, 1; tibia: I: 2, 3/2, 3/1, 2; II: 2, 1/1, 3/1, 2; III: 2, 1/1, 2/1, 1; IV: 2, 1/1, 3/1, 2; tarsi I: not counted, II: 18; III: 18; IV: 18. All legs with smooth setae; tarsi of legs II-IV, but not other segments, with some setae much longer than others (Fig. 24).

Adult male. Unknown.

Etymology. The term “ xerophilus ” derives from xeros “Greek for dry” + “ philos ” “Greek for friend” referring to the arid habitat (Caatinga) where the types of this new species were collected.

Remarks. As reported for C. luizgonzagai the positions of some of the leg setae are unusual in comparison with what has been reported for other free-living Mesostigmata (Evans, 1963), namely as follows: seta pd 2 of legs II and IV more basal; seta al 2 of legs II and III more distal; seta av 2 of legs II–IV more distal (inserted anteriad of level of md); seta ad 3 of legs II–IV more basal.

Cheiroseius xerophilus is most similar to C. ferratus Karg, 1981, but females of the latter have metapodal plates, J 5 smooth, J 4 longer than distance between its base and the base of J 5 and four pairs of opisthogastric setae on unsclerotised cuticle flanking ventrianal shield.

This new species seems to be distinguished from other Cheiroseius by the type of habitat from which the type specimens were collected. While species of this genus have usually been reported from wet habitats (Moraes et al., 2015), the type specimens of C. xerophilus were found in litter collected from a dry habitat (disturbed natural vegetation of the Caatinga, biome exclusively found in northeastern Brazil). The average annual rainfall in the type locality is nearly 750 mm (Climate-data.org, 2017).