Ixodes rio D. Apanaskevich & Labruna 2022, n. sp.
Creators: name: Apanaskevich, Dmitry A.
name: Apanaskevich, Maria A.
name: Klimov, Pavel B.
name: Edgy, Brett M.
name: Bermúdez, Sergio E.
name: Labruna, Marcelo B.
name: Korzeev, Andrei I.
name: Barker, Stephen C.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Ixodida
Ixodidae
Ixodes
Ixodes rio

description: Ixodes rio D. Apanaskevich & Labruna n. sp.
Type-host: Variable antshrike— Thamnophilus caerulescens Vieillot (Passeriformes: Thamnophilidae).
Other hosts: Rufous-capped antshrike— Thamnophilus ruficapillus Vieillot (Passeriformes: Thamnophilidae), white-necked thrush— Turdus albicollis Vieillot (Passeriformes: Turdidae).
Type-locality: Brazil: Rio de Janeiro: Serra do Itatiaia, Alto do Itatiaia.
Other locality: Brazil: Paraná: Tijucas do Sul.
Type-material: Holotype female, from T. caerulescens, Alto do Itatiaia (~ 22°22’S, 44°37’W), Serra do Itatiaia, Rio de Janeiro, Brazil, 2.ii.1922, E. G. Holt (EGH); deposited in the USNTC (USNMENT 01481794). Paratypes: 6 females. Brazil: Paraná: Tijucas do Sul (~ 25°55’S, 49°11’W): 1 female, from T. albicollis, 2.xi.2000, M. Arzua and A. Bispo, CNC-976; Rio de Janeiro: Serra do Itatiaia, Alto do Itatiaia: 4 females, from T. caerulescens, 2.ii.1922, EGH, USNMENT 00987157; same locality: 1 female, from T. ruficapillus, 10.ii.1922, EGH, USNMENT 00987151. All paratypes with USNMENT numbers are deposited in the USNTC and that with CNC number is in the CNC.
ZooBank registration: The Life Science Identifier (LSID) for Ixodes rio n. sp. is urn:lsid:zoobank.org:act: 13C2F3B1- ABED-49EE-BB33-C956555CF102.
Etymology: The species is named after Rio de Janeiro, the state of Brazil, where the holotype and most of the paratypes were collected.
Description. Female [Based on 7 specimens; Figs. 28, 29.] Idiosoma (Fig. 28A, F) length from scapular apices to posterior body margin in nearly unfed specimen 1.86 (n = 1), maximal width in nearly unfed specimen 1.08 (n = 1), ratio 1.72 (n = 1), broadly suboval, widest posterior to mid-length. Scutum (Fig. 28B, C) length 1.02–1.14 (1.05 ± 0.05; n = 6), width 0.72–0.80 (0.74 ± 0.03; n = 6), ratio 1.34–1.44 (1.41 ± 0.04; n = 6); lateral margins diverging for approximately 1/2 of scutal length, then converging to broadly rounded posterior margin; lateral carinae absent; cervical grooves very shallow reaching posterior quarter of scutal length; relatively sparse very fine punctations evenly distributed throughout scutum; setae (Fig. 28B, C) relatively sparse, very short (c. 0.03–0.04 in anterolateral margin of scutum). Alloscutum (Fig. 28A) as illustrated; setae (Fig. 28A, D, E) numerous, evenly distributed, very short in center of alloscutum: c. 0.02 and long in area medial to marginal grooves: c.0.06–0.08 (avg. 0.07), setae in area medial to marginal grooves 3.00–4.50 (avg. 4.00) times longer than setae in center of alloscutum, ratio scutal length to length of setae in area medial to marginal grooves 13.49–16.96 (15.18 ± 1.40; n = 6). Venter (Fig. 28F) as illustrated; genital aperture (Fig. 28F) medial to posterior margin of coxae III; genital groove (Fig. 28F) well developed; anal groove (Fig. 28F) oval with open posterior margin; ventral setae (Fig. 28F) numerous, length of preanal setae c. 0.05, evenly distributed. Spiracular plates (Fig. 29A) length 0.25–0.29 (0.27 ± 0.02; n = 6), width 0.26–0.30 (0.27 ± 0.02; n = 6), ratio 0.94–1.03 (0.99 ± 0.04; n = 6); subcircular.
Gnathosoma (Fig. 29B–D) length from palpal apices to cornual apices dorsally 0.51–0.59 (0.55 ± 0.03; n = 6), width of basis capituli dorsally 0.44–0.49 (0.45 ± 0.02; n = 6), ratio 1.14–1.28 (1.21 ± 0.05; n = 6). Dorsal basis capituli (Fig. 29B) length from medial insertion of palpal segment I to cornual apices 0.18–0.21 (0.20 ± 0.01; n = 6), ratio width to length 2.12–2.48 (2.31 ± 0.13; n = 6), subhexagonal: with short and angular lateral projections, posterior margin slightly convex; cornua short, length 0.01–0.03 (0.02 ± 0.01; n = 6), ratio total length of basis capituli, including cornua, to cornual length 7.50–14.50 (10.00 ± 2.73; n = 6), triangular with broadly rounded apex; transversally suboval porose areas large, width 0.13–0.15 (0.13 ± 0.01; n = 6), ratio basis capituli width dorsally to porose area width 3.25–3.60 (3.47 ± 0.17; n = 6), clearly distinct, not indented, separated by distance of nearly half of their own width, openings discrete. Ventral basis capituli (Fig. 29C, D) pentagonal; auriculae long, length 0.05–0.07 (0.06 ± 0.01; n = 6), ratio gnathosoma length to auriculae length 8.73–11.27 (9.64 ± 0.92; n = 6), narrow, nearly twice as long as wide, slightly recurved inwardly to narrowly rounded apex. Lateral surface of basis capituli concave (Fig. 29C, D). Palpi (Fig. 29B, C, E) moderately long, length dorsally (segments II and III) 0.28–0.33 (0.30 ± 0.02; n = 6), maximum width (in dorsolateral plane) 0.10–0.12 (0.10 ± 0.01; n = 6), ratio 2.63–3.06 (2.87 ± 0.16; n = 6), length of medial margin of palpal segment I ventrally 0.14 (n = 6); segment I with moderately long internal projection directed anteriorly and giving L-shape to segment I dorsally and ventrally; length of internal projection ventrally from base of palpal segment II to anterior apex 0.10–0.11 (0.11 ± 0.01; n = 6), ratio combined length of palpal segments II and III to length of internal projection on palpal segment I ventrally 2.61–3.19 (2.83 ± 0.19; n = 6); dorsally segment I without mesodorsal spur, with slight transversal ridge at base and small blunt or tapering dorsoapical denticle; segments II and III fused with indistinct or barely discernible (mostly medially) suture between them, narrow proximally and gradually widening to broadly rounded apex. Hypostome (Fig. 29C) length 0.32–0.34 (0.33; n = 2), width 0.10 (n = 1), ratio 3.17 (n = 1); base of hypostome nearly at same level as base of palpal segments II, club-shaped, widest close to mid-length; dental formula mostly 4/4, proximal rows 2/2 and then 3/3, distal rows 5/5; denticles sharply pointed; proximal part of hypostome without denticles moderate in length.
Legs moderately long, slender. Coxae (Fig. 29F): coxae I-III with internal and external spurs, coxa IV with external spur only; external spur on coxae I-III moderately long, subequal in length, narrow, narrowly rounded at apex, directed posteromedially; external spur on coxa IV same as on other coxae but twice shorter; internal spur on coxae I-III short, decreasing in size from coxa I to III, narrow, narrowly rounded at apex, directed posteromedially; external spur on coxa I nearly twice as long as internal spur; no syncoxae. Distally trochanters I-IV (Fig. 29F) with moderate ventral spur with narrowly rounded apex. Tarsus I length 0.65–0.67 (0.66; n = 4); tarsus IV length 0.62–0.63 (0.63; n = 4).
Remarks. The descriptions and illustrations of female of I. auritulus in Keirans and Clifford (1978), BarrosBattesti et al. (2003) and Onofrio et al. (2009) were partially or entirely based on specimens of I. rio n. sp.
By having a distinct, anteriorly directed internal projection on palpal segment I, the female of I. rio n. sp. most closely resembles the following Ixodes (Multidentatus) spp.: I. auritulus, I. brevisetosus n. sp., I. contrarius n. sp., I. cornuae, I. guglielmonei n. sp., I. insulae n. sp., I. kerguelenensis, I. moralesi n. sp., I. paranaensis, I. percavatus, I. robbinsi n. sp., I. tinamou n. sp. and I. zealandicus.
The female of I. rio n. sp. can be distinguished from the female of I. cornuae by having short cornua (vs very long cornua in that species); from females of I. kerguelenensis and I. percavatus by having the indistinct mesodorsal spur on palpal segment I (vs large, distinct spur in those species); from the female of I. paranaensis by having longer auriculae (vs very short auriculae in that species) (see Arthur 1960; Wilson 1970; Barros-Battesti et al. 2003).
The female of I. rio n. sp. can be distinguished from females of other species by the narrow scutum: mean ratio length to width 1.41 (vs broader scutum: mean ratio 1.19 in I. auritulus, 1.25 in I. guglielmonei n. sp. and I. moralesi n. sp., 1.16 in I. robbinsi n. sp. and 1.14 in I. tinamou n. sp.); short setae in center of alloscutum and long setae in alloscutal area medial to marginal grooves: mean ratio length of setae in alloscutal area medial to marginal grooves to length of setae in center of alloscutum 4.00 (vs shorter setae in alloscutal area medial to marginal grooves: mean ratio 1.58 in I. brevisetosus n. sp.; longer setae in both center and area medial to marginal grooves of alloscutum: mean ratio 1.09 in I. guglielmonei n. sp., 2.00 in I. insulae n. sp. and 1.14 in I. zealandicus); long setae of alloscutum medial to marginal grooves: mean ratio length of scutum to length of alloscutal setae medial to marginal grooves 15.18 (vs shorter setae of alloscutum medial to marginal grooves: mean ratio 45.62 in I. brevisetosus n. sp., 20.89 in I. moralesi n. sp., 26.93 in I. robbinsi n. sp.); broad gnathosoma: mean ratio length of gnathosoma to width of basis capituli 1.21 (vs narrower gnathosoma: mean ratio 1.33 in I. brevisetosus n. sp. and I. zealandicus and 1.34 in I. insulae n. sp.); short angular dorsolateral projections of basis capituli (vs all these species, except for I. brevisetosus n. sp., have basis capituli without angular dorsolateral projections); lateral surface of basis capituli concave (vs lateral surface flat in I. brevisetosus n. sp.); posterior margin of basis capituli slightly convex (vs sinuously concave in I. guglielmonei n. sp. and straight to very slightly concave in I. zealandicus); short cornua: mean ratio length of basis capituli to cornual length 10.00 (vs longer cornua: mean ratio 6.00 in I. auritulus, 4.94 in I. guglielmonei n. sp., 4.60 in I. insulae n. sp. and 5.87 in I. moralesi n. sp.); narrow porose areas: mean ratio width of basis capituli to width of porose area 3.47 (vs broader porose areas: mean ratio 2.92 in I. auritulus, 2.97 in I. contrarius n. sp., 2.91 in I. guglielmonei n. sp., 3.03 in I. insulae n. sp., 2.83 in I. robbinsi n. sp. and 2.93 in I. zealandicus); auriculae long: mean ratio length of gnathosoma dorsally to length of auriculae 9.64, narrow, directed posteriorly or slightly curved inwardly, with narrowly rounded apex (vs shorter auriculae: mean ratio 28.15 in I. guglielmonei n. sp., 14.59 in I. robbinsi n. sp., 43.38 in I. tinamou n. sp. and 19.54 in I. zealandicus; auriculae distinctly broader, directed slightly outwards, with broadly rounded apex in I. guglielmonei n. sp., I. moralesi n. sp., I. robbinsi n. sp., I. tinamou n. sp. and I. zealandicus); lacking spur at base of palpal segment I dorsally (vs short mesodorsal spur at base of palpal segment I dorsally in I. insulae n. sp., I. moralesi n. sp. and I. zealandicus); moderately long internal projection on palpal segment I: mean ratio length of palpal segments II and III to length of internal projection on palpal segment I 2.83 (vs longer projection: mean ratio 1.88 in I. contrarius n. sp.; shorter internal projection: mean ratio 4.94 in I. guglielmonei n. sp., 3.55 in I. insulae n. sp., 3.69 in I. tinamou n. sp. and 4.50 in I. zealandicus); indistinct or short dorsoapical spur on palpal segment I (vs moderate spur in I. auritulus, I. brevisetosus n. sp., I. insulae n. sp. and I. zealandicus; large, hook-like spur in I. moralesi n. sp.), narrower palpal segments II and III: mean ratio length to width 2.87 (vs broader segments: mean ratio 2.53 in I. contrarius n. sp., 2.16 in I. guglielmonei n. sp., 2.46 in I. moralesi n. sp., 2.41 in I. robbinsi n. sp. and I. tinamou n. sp. and 2.42 in I. zealandicus); external spur on coxae I-IV relatively long, narrow, sharp at apex (vs shorter, broader spur with broadly rounded apex in I. tinamou n. sp. and I. zealandicus); generally smaller species: see description for measurements (vs noticeable larger species: I. auritulus, I. brevisetosus n. sp., I. guglielmonei n. sp., I. insulae n. sp., I. moralesi n. sp., I. robbinsi n. sp. and I. tinamou n. sp.; noticeably smaller species: I. contrarius n. sp. See descriptions for measurements).
Collection data for I. rio n. sp. are listed in the material above. Collections of this species were made in Brazil (Paraná and Rio de Janeiro States) (Fig. 10E). Females of this species were collected from passeriform birds: the white-necked thrush, T. albicollis (Passeriformes: Turdidae), variable antshrike, T. caerulescens and the rufouscapped antshrike, T. ruficapillus (Passeriformes: Thamnophilidae) during February and November.
description: Published as part of Apanaskevich, Dmitry A., Apanaskevich, Maria A., Klimov, Pavel B., Edgy, Brett M., Bermúdez, Sergio E., Labruna, Marcelo B., Korzeev, Andrei I. & Barker, Stephen C., 2022, Description of eight new species of Ixodes Latreille, 1795 (Acari: Ixodidae) and redescription of I. auritulus Neumann, 1904, parasites of birds in the Australasian, Nearctic and Neotropical Regions, pp. 1-73 in Zootaxa 5173 (1) on pages 49-53, DOI: 10.11646/zootaxa.5173.1.1, http://zenodo.org/record/6966076