Rhodacarus emilianoi, 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 : 76-78

Rhodacarus emilianoi sp. nov.

Diagnosis (adult female). Epistome with an anteromedian extension of about uniform width along its entire length and distally denticulate, flanked by a pair of shorter (about half the length) and aciculate anterolateral extensions; podonotal shield without a line posteriad setae j 4, z 3 and s 2; seta r 4 on unsclerotised cuticle laterad podonotal shield; seta Z 3 shorter than distance Z 3– Z 4; without presternal platelets; seta Zv 1 on unsclerotised cuticle anteriad ventrianal shield; seta Jv 5 on ventrianal shield; with a pair of ellipsoidal metapodal platelets.

Description

Adult female (five specimens measured)

( Figures 11–19 )

Gnathosoma. Fixed cheliceral digit 55 (53–58) long (from apex to dorsal lyrifissure), with five teeth in addition to the apical tooth and a setiform pilus dentilis ( Fig. 11 ); movable cheliceral digit 57 (55–59) long, with three teeth in addition to 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 anteromedian extension of about uniform width along its entire length and distally denticulate, flanked by a pair of shorter and aciculate anterolateral extensions; margins smooth ( Fig. 12 ). Number of setae on palp trochanter-tibia: 2–5–6–14; all aciculate and smooth; apotele 3-tined. Deutosternum delimited by lateral lines, with nine roughly transverse lines ( Fig. 13 ), each with 5–8 denticles each, the second and eighth lines, concave, and others about straight; two pairs of smooth lines laterad of deutosternal groove (slightly anterior to eight and in line with ninth transverse deutosternal line). Internal malae with outer margins denticulate and inner margins smooth. Corniculi horn-like, 28 (27–30) long and 7 (7–9) wide at the base. Setae h 1– h 3 and pc about in longitudinal line, as typical for the genus. Measurements of setae: h 1 15 (13–16), h 2 9 (8–10), h 3 9 (8–10), pc 10 (9–12); all aciculate and smooth.

Idiosoma. 288 (276–297) long and 155 (150–157) wide.

Dorsal idiosoma ( Fig. 14 ). Podonotal shield smooth, except for punctate bands in the anterior and posterior margins; 146 (140–150) long and 149 (144–152) wide; with 22 pairs of setae (j 1– j 6, z 1–z6, s 1– s 6, r 2, r 3, r 5 and r 6), six pairs of distinguishable lyrifissures, one pair of distinguishable pores, and three scleronoduli (internal densely sclerotised structures) between j 5 and j 6. Unsclerotised cuticle along lateral margins of podonotal shield with a pair of setae (r 4). Opisthonotal shield smooth, except for punctate band in the anterior margin; 135 (128–138) long and 103 (98–108) wide; with 17 pairs of setae (J 1– J 5, Z 1– Z 5, S 1– S 5, R 2 and R 3 ) and ten pairs of distinguishable lyrifissures. Unsclerotised cuticle along lateral margins of opisthonotal shield with three pairs of setae ( R 1 , R 4 and R 5 ). Measurements of setae: j 1 11 (10–12), j 2 10 (9–11), j 3 11 (10–12), j 4 11 (10–12), j 5 11 (10–12), j 6 12 (11–13), z 1 5 (4–6), z 2 6 (5–7), z 3 11 (10–12), z 4 11 (10–12), z 5 12 (11–13), z 6 13 (11–15), s 1 5 (4–6), s 2 10 (9–12), s 3 7 (6–8), s 4 15 (12–16), s 5 15 (14–16), s 6 13 (12–14), r 2 9 (8–10), r 3 17 (15–19), r 4 6 (5–7), r 5 10 (10–12), r 6 12 (10–13), J 1 13 (12–14), J 2 11 (10–12), J 3 12 (11–13), J 4 15 (13–16), J 5 8 (7–9), Z 1 13 (12–15), Z 2 11 (9–13), Z 3 13 (11–15), Z 4 14 (13–15), Z 5 29 (27–30), S 1 8 (7–9), S 2 9 (8–11), S 3 8 (7–9), S 4 9 (8–10), S 5 12 (11–13), R 1 6 (4–7), R 2 6 (5–7), R 3 6 (5–7), R 4 5 (4–6), R 5 16 (17–19); all aciculate and smooth.

Ventral idiosoma ( Fig. 15 ). Base of tritosternum 9 (8–11) long and 8 (6–9) wide proximally; laciniae 61 (60–62) long, separated for about 90% of their length, fimbriate. Without presternal platelets. Sternal shield smooth, except for a weakly sclerotised and punctate region anterior to first pair of lyrifissures; 98 (96–100) long, including the weakly sclerotised and punctate region, and 66 (65–68) wide at widest level; with four pairs of setae (st 1– st 4) and three pairs of lyrifissures (iv 1– iv 3). Genital shield smooth, except for a punctate band in the posterior margin; 77 (74–81) long (including hyaline flap) and 28 (27–31) wide at level of posterior margin; with one pair of setae (st 5) and one pair of lyrifissures (iv 5); distance between st 5– st 5 38 (37–40); posterior margin slightly convex. Ventrianal shield smooth, except for a punctate band in the anterior margin; 96 (94–98) long and 72 (70–76) wide; with five pairs of setae (Jv 1– Jv 3, Jv 5 and Zv 2) in addition to circum-anal setae, and four pairs of distinguishable lyrifissures. Unsclerotised cuticle anteriad ventrianal shield with one pair of setae (Zv 1). With a pair of ellipsoidal metapodal platelets [20 (19–22) long]. Peritreme short, extending anteriorly to level of middle of coxa III. Elongated peritrematic plate, reaching posterior to coxa II. Measurements of setae: st 1 11 (10–13), st 2 12 (11–13), st 3 12 (11–13), st 4 12 (11–13), st 5 9 (8–10), Jv 1 10 (9–11), Jv 2 10 (9–11), Jv 3 11 (10–12), Jv 5 8 (7–10), Zv 1 9 (8–11), Zv 2 9 (8–10), para-anal 17 (16–19), post-anal 32 (30–34); all aciculate and smooth.

Spermatheca. Not distinguishable.

Legs ( Figs. 16–19 ). Leg lengths: I—272 (265–275), II—174 (170–179), III—160 (157–165), IV—225 (215– 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 1–0/1, 1/1–2, II 1–0/3, 0/1–1, III 1–0/2, 0/2–0, IV 1–0/2, 0/2–0, femora I 2–2/2, 3/2–2, II 2–3/2 2/1–1, III 1–2/1, 2/0–0, IV 1–2/1, 2/0–0; genua I 2–3/3, 2/2–1, II 2–3/1, 2/1–2, III 2–2/1, 2/1–1, IV 1–1/1, 4/2–1; tibiae I 2–2/2, 4/2–2, II 2–2/1, 2/1–2, III 1–1/1, 2/1–1, IV 1–2/1, 2/2–2; tarsi I not counted, II–IV 18 setae each. Setae similar to each other in shape and length (I–IV), except pd trochanter (lanceolate) and pd 3 femur (short) of leg I. Pretarsi only on legs II–IV.

Adult male. Not found.

Specimens examined. Holotype and four paratype females from litter/soil of a fragment of the Cerrado biome at Sucupira (1°54’36.576”S, 48°51’10.084’’W; 250 m above sea level), Tocantins state, Brazil, in April 2020 and December 2021.All types collected by E.B. Azevedo and A.F. Braga, and deposited in the Mite Reference Collection of Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” ( ESALQ), Universidade de São Paulo ( USP), Piracicaba, São Paulo state, Brazil.

Etymology. The name emilianoi is an honour of Dr. Emiliano Brandão de Azevedo, for his friendship and invaluable contribution in this study.

Remarks. Rhodacarus emilianoi is similar to Rhodacarus gracilis Shcherbak, 1980 and Rhodacarus fatrensis Kalúz, 1994 , but females of the two latter species have the length of the anterolateral extensions of epistome ≤ onethird of the length of the anteromedian extension; seta Z 3 longer than distance Z 3– Z 4; and seta Jv 5 on unsclerotised cuticle laterad ventrianal shield.

Figures

FIGURE 11–13. Rhodacarus emilianoi sp. nov., adult female. 11. Lateral (Antiaxial) view of chelicera; 12. Epistome; 13. Hypostome.

FIGURES 14–15. Rhodacarus emilianoi sp. nov., adult female. 14. Dorsal idiosoma; 15. Ventral idiosoma.

FIGURE 16–19. Rhodacarus emilianoi sp. nov., adult female. 16 Leg I, coxa-tibia, dorsal view; 17. Leg II, dorsal view; 18. Leg III, dorsal view; 19. IV, dorsal view.