Binodacarus tocantinensis, Braga & Castilho, 2024

Braga, Alice Freitas & Castilho, Raphael De Campos, 2024, New species of Binodacarus and Rhodacarus mites (Mesostigmata: Rhodacaridae) from Brazilian Cerrado biome, and a key to the world species of the genera, Zootaxa 5497 (1), pp. 70-82 : 71-75

Binodacarus tocantinensis sp. nov.

Diagnosis (adult female). Fixed cheliceral digit with five teeth in addition to the apical tooth; deutosternum with seven roughly transverse lines of denticles; four scleronoduli (internal densely sclerotised structures) between setae j 5 and j 6; seta s 3 on podonotal shield; seta s 5 about in transverse line with s 6; seta S 4 on opisthonotal shield; with two small transversely elongate sclerites and two ellipsoidal platelets between genital and ventrianal shields; setae Jv 1, Zv 1 and Zv 3 on ventrianal shield; metapodal platelets elongate and long; setae of trochanter II similar to each other, aciculate.

Description

Adult female (five specimens measured)

( Figures 1–10 )

Gnathosoma. Fixed cheliceral digit 39 (37–41) long (from apex to dorsal lyrifissure), with five teeth in addition to the apical tooth and a setiform pilus dentilis ( Fig. 1 ); movable cheliceral digit 41 (39–42) long, with three teeth in addition to the apical tooth; antiaxial and dorsal lyrifissures as well as dorsal seta distinct; arthrodial process of chelicera shaped as a short coronet-like fringe. Epistome with an acuminate anteromedian extension; margins serrated ( Figures 2, 3 ). Number of setae on palp trochanter-tibia: 2–5–6–14; setae aciculate and smooth, except palp trochanter al, slightly serrated ( Fig. 4 ); apotele 3–tined. Deutosternum delimited by lateral lines, with seven roughly transverse lines, each with 3–6 denticles each; five pairs of smooth lines laterad deutosternal groove (behind first, third, fourth, fifith and sixth transverse deutosternal line). Internal malae almost reaching level of tip of corniculi; outer margin fimbriate and inner margin smooth. Corniculi horn-like, 20 (19–21) long and 6 (5–7) wide at the base. Setae h 3 about in longitudinal line with h 1 and slightly posteriad and mediad h 2. Measurements of setae: h 1 11 (10–12), h 2 4 (3–5), h 3 7 (6–8), pc 9 (8–10); all aciculate and smooth.

Idiosoma. 285 (276–295) long and 137 (124–157) wide.

Dorsal idiosoma ( Fig. 5 ). Unsclerotised cuticle along anterior margin of podonotal shield punctate. Podonotal shield smooth, with a punctate band in the posterior margin; 141 (138–144) long and 117 (112–121) wide; with 15 pairs of setae (j 1– j 6, z 2–z6 and s 3– s 6), six pairs of distinguishable lyrifissures, two pairs of distinguishable pores, and four scleronoduli between setae j 5 and j 6. Unsclerotised cuticle along margins of podonotal shield with two pairs of platelets and seven pairs of setae (z 1, s 1, s 2 and r 2– r 5). Opisthonotal shield smooth, with a reticulate band in the anterior margin; 145 (139–152) long and 99 (94–101) wide; with 15 pairs of setae (J 1– J 5, Z 1– Z 5 and S 1– S 5), and seven pairs of distinguishable lyrifissures. Unsclerotised cuticle along lateral margins of opisthonotal shield with five pairs of setae ( R 1 – R 5 ) and a pair of distinguishable lyrifissures (rp). Measurements of setae: j 1 10 (9–12), j 2 6 (5–7), j 3 5 (4–6), j 4 6 (5–7), j 5 5 (4–6), j 6 5 (4–6), z 1 3 (2–4), z 2 6 (5–7), z 3 6 (5–7), z 4 6 (5–7), z 5 6 (5–7), z 6 7 (6–8), s 1 5 (4–6), s 2 5 (4–6), s 3 6 (5–7), s 4 6 (5–7), s 5 6 (5–7), s 6 5 (4–5), r 2 6 (5–7), r 3 7 (6–8), r 4 5 (4–6), r 5 5 (3–5), J 1 6, J 2 5, J 3 5 (4–6), J 4 5 (4–6), J 5 6 (5–7), Z 1 6 (5–7), Z 2 5 (4–6), Z 3 6 (5–7), Z 4 6 (5–7), Z 5 10 (9–11), S 1 5, S 2 5 (4–6), S 3 5 (4–6), S 4 5 (4–6), S 5 7 (5–8), R 1 4 (3–5), R 2 3 (2–4), R 3 3 (2–4), R 4 4 (3–5), R 5 5 (4–6); all aciculate and smooth.

Ventral idiosoma ( Fig. 6 ). Base of tritosternum 7 (6–8) long and 5 (5–6) wide proximally; laciniae 50 (48–51) long, separated for about 80% of their total length, fimbriate. Sternal shield smooth, except for a weakly sclerotised and punctate region anterior to first pair of lyrifissures; 101 (97–104) long, including the weakly sclerotised and punctate region, and 72 (71–73) wide at widest level (between coxae II and III); with four pairs of setae (st 1– st 4) and three pairs of lyrifissures, posterior margin slightly concave. Genital shield smooth, except for a punctate band in the posterior margin; 39 (35–41) long (including punctate region) and 44 (42–45) wide at level of posterior margin; with one pair of setae (st 5); distance between st 5– st 5 38 (37–40), posterior margin truncate. Lyrifissure iv 5 on unsclerotised cuticle, laterad of st 5. Two small transversely elongate sclerites and two ellipsoidal platelets present between genital and ventrianal shields. Ventrianal shield smooth, except for a weakly sclerotised and punctate region in the anterior margin; 112 (109–115) long and 96 (94–98) wide; with seven pairs of setae (Jv 1– Jv 3, Jv 5 and Zv 1– Zv 3) in addition to circum-anal setae, and two pairs of distinguishable lyrifissures. Peritreme C-shaped, punctate, greatly reduced, only slightly longer than the diameter of stigma. Peritrematic plate restricted to peritreme. Exopodal plates not distinguishable. With a pair of elongate metapodal platelets [41 (40–43) long]. Measurements of setae: st 1 11 (10–12), st 2 8 (7–9), st 3 8 (7–9), st 4 7 (6–8), st 5 6 (5–7), Jv 1 6 (5–7), Jv 2 6 (5–7), Jv 3 5 (4–6), Jv 5 9 (8–10), Zv 1 5 (4–6), Zv 2 4 (3–5), Zv 3 5 (3–6), para-anal 7 (6–8), post-anal 10 (9–11); all aciculate and smooth.

Spermatheca. Not distinguishable.

Legs ( Figures 7–10 ). Leg lengths: I—235 (225–248), II—180 (171–198), III—162 (149–178), IV—233 (231– 237). Chaetotaxy: 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 1–1/2, 0/1–1, II 1–0/1, 0/2–1, III 1–1/2, 0/1–0, IV 1–1/1, 0/2–0; femora I 2–2/2, 3/2–2, II 1 2/1, 3/2–1, III 1–2/1, 2/0–0, IV 1–2/1, 1/0–1; genua I 2–2/1, 4/2–2, II 2–3/1, 2/1–2, III 2–2/1, 2/0–1, IV 2–3/1, 2/1–1; tibiae I 2–2/2, 4/2–2, II 2–2/1, 2/1–2, III 1–2/1, 2/1–1, IV 2–1/1, 3/1–2; tarsi I not counted, II–IV 18 setae each. Setae of femora, genua and tibiae I–IV similar to each other in lengths (8–13 µm), except trochanter I av 2 (3 µm) and ad spine-like (5 µm), and femur I ad 2 (3 µm). Seta pd 2 of tarsus IV (16–17 µm) erect, slightly longer than other dorsal setae of the same segment (11–13 µm). Pretarsi I–IV similar to each other in shape and length, each consisting of an elongate ambulacral stalk a pair of strongly sclerotised claws and three rounded pulvillar lobes.

Adult male. Not found.

Specimens examined. Holotype and four paratype females from litter/soil of a fragment of the Cerrado biome at Sucupira (11°50’10.8”S, 48°54’18.77.084’’W; 250 m above sea level), Tocantins state, Brazil, in December 2020. All types collected by A. F. Braga and deposited in the Mite Reference Collection of the Department of Entomology and Acarology, Escola Superior de Agricultura “Luiz de Queiroz” ( ESALQ), Universidade de São Paulo ( USP), Piracicaba, São Paulo, Brazil.

Etymology. The specific name tocantinensis is an adjective indicating the state in which the type specimens were collected.

Remarks. Until the present study, Binodacarus mites were only found in Brazil. Binodacarus tocantinensis is similar to Binodacarus aceguensis Duarte et al., 2016 , but females of the latter have a fixed cheliceral digit with four teeth in addition to the apical tooth; deutosternum with six roughly transverse lines; seta s 5 anteriad s 6; setae Zv 1 and Zv 3 on unsclerotised cuticle around ventrianal shield; metapodal platelets elongate and short (≅ 15 μm); anterolateral seta of trochanter II brush-like.

Binodacarus tocantinensis is also similar to Binodacarus brasiliensis Castilho & Moraes, 2010 , but females of the latter have fixed cheliceral digit with four teeth in addition to the apical tooth; podonotal shield with two scleronoduli between setae j 5 and j 6; setae s 3 and S 4 on unsclerotised cuticle laterad podonotal shield; seta s 5 anteriad s 6; setae Jv 1 and Zv 1 on unsclerotised cuticle around ventrianal shield; metapodal platelets subdivided into a small anterior fragment and a larger posterior fragment.

Figures

FIGURE 1–4. Binodacarus tocantinensis sp. nov., adult female. 1. Lateral (Antiaxial) view of chelicera; 2. Epistome; 3. Epistome (DIC micrograph); 4. Hypostome.

FIGURES 5–6. Binodacarus tocantinensis sp. nov., adult female. 5. Dorsal idiosoma; 6. Ventral idiosoma.

FIGURE 7–10. Binodacarus tocantinensis sp. nov., adult female. 7. Leg I, coxa-tibia, dorsal view; 8. Leg II, dorsal view; 9. Leg III, dorsal view; 10. IV, dorsal view.