Ixodes collaris Hornok 2016
Creators: name: Hornok, Sándor
name: Murányi, Dávid
name: Kontschán, Jenő
name: Tu, Vuong Tan
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Ixodida
Ixodidae
Ixodes
Ixodes collaris

description: Ixodes collaris Hornok, 2016   
 Description   
 Male. [See Figs. 1–3.] Length of idiosoma (from half point between scapular apices to posterior margin) 4.49, breadth 2.78, ratio of idiosomal length/breadth 1.61. Conscutum centrally dark brown, laterally lightly colored, elongated, elliptical, broadest slightly anteriorly to its mid-length (Fig. 1b). Length of scutum 4.2, breadth 2.45, ratio length/breadth 1.71. Cervical grooves anteriorly well-defined, paramedian grooves posteriorly shallow; scattered punctuations present. Genital aperture at level of second intercoxal space, surrounded by ivory color and scattered punctuations (Fig. 2b). Spiracular plates slightly oval (length/breadth ratio 1.23), with eccentric opening. Ivory coloration anterior to anus oval, elongated. Anal plate oval, elongated, broadest at mid-length. Adanal plates 1.5 times longer than anal plate. Median plate anteriorly rounded, longer than broad (Figs. 2b, d, 3b).   
Gnathosoma: length from palpal apices to posterior margin of basis 0.78, width of basis dorsally 0.48, ratio of length to width 1.63. Basis capituli dorsally broadest at base of palpi, with laterally and posteriorly elevated, backwardly diverging (trapezoid), dark, sclerotized ridge (Fig. 1d). Basis capituli ventrally trapezoidal, posteriorly tapering (Fig. 2b). Palpi relatively short, length (dorsally) 0.53, breadth 0.21, ratio length/breadth 2.52. Palpal segment I. 0.04, II-III (with indistinct separation) 0.48 long. Segments II-III curved both medially and laterally, with uneven surface (Fig. 1d). Palpal setae long anteriorly, showing sparse distribution laterally (less than 10 in number), on segments II-III up to 0.21 long (i.e. equal to width of palpi (Fig. 1d). Hypostome conical, length 0.26, breadth at basis 0.15, ratio length/breadth 1.73. Teeth poorly defined, with dental formula 3/3.  
Legs long. Hallerʼs organ elongated, longer than maximum breadth (diameter) of tarsus I (length: 1.37). Coxae medially rounded, without spines or spurs, but with short (0.07) setae (Figs. 2b, 3b).  
 Larva. [See Figs. 4–6.] Length of idiosoma 0.96, breadth 0.76, ratio idiosomal length/breadth 1.26. Scutum pentagonal, posteriorly rounded, broadest slightly anteriorly to its mid-length (Fig. 4b), with rough surface. Length of scutum 0.52, breadth 0.49, ratio length/breadth 1.06. Cervical grooves long, ending at deepest point of concavely curved posterolateral margin of scutum (Fig. 4b). Scutal setae absent. Alloscutal setae longest caudally; central dorsal setae (Cd1: 0.045, Cd2: 0.047) shorter than marginal dorsal setae (Md1-Md8: 0.088, 0.096, 0.105, 0.112, 0.125, 0.108, 0.133 and 0.148, respectively). Sternal setae ventrally (St1: 0.056, St2: 0.051; St3: 0.062) shorter than premarginal setae (Pm1-Pm4: 0.072, 0.075, 0.076 and 0.071, respectively) and preanal setae (Pa1: 0.064; Pa2: 0.078); marginal ventral setae longest (Mv1: 0.092; Mv2: 0.118; Mv3: 0.128) (Fig. 5c, d).   
Gnathosoma: length from palpal apices to posterior margin of basis 0.34, width of basis capituli dorsally 0.25, ratio of length to width 1.36. Basis capituli dorsally triangular, with straight posterior margin. Ventral basis with 2 pairs of short (0.015) posthypostomal setae. Strongly concave caudolateral margin of ventral basis with perpendicular angle and dark sclerotized edge (“collar”) at and behind maximum width of basis (Fig. 6b). Posterior margin of ventral basis rounded (Fig. 6b). Palpi elongated, club-shaped, curved both medially and laterally. Palpal length dorsally 0.24, breadth 0.07, ratio length/breadth 3.4. Segments I-III measure 0.03, 0.13 and 0.08, respectively. Palpal setae longest (0.06) near junction of segments II-III. Hypostome conical, short (0.11), with dental formula 2/2.  
Legs long. Hallerʼs organ elongated, longer than maximum breadth (diameter) of tarsus I (length: 0.48) (Figs. 4b, 5c, d, 6d,). Coxae medially rounded, without spines or spurs. Medial margins of coxae I-II straight, nearly equal in length; those of coxae III rounded (Fig. 6d). Coxae I-II with short (0.04) setae (2 and 1, respectively: Fig. 5d).  Differential diagnosis  
 Prior to its discovery, I. collaris may have been misidentified as I. vespertilionis in Southeast Asia (e.g. in [3]). Therefore, the differential diagnosis (see Figs. 1, 2, 4 and 6) focuses on the latter species, as redescribed in [4] and [5]. Apart from data taken from the latter source on larvae of I. simplex Neumann, 1906, the redescription of the male of I. simplex was also taken into account [6], together with measurements (including those of I. ariadnae Hornok, 2014) in [7].   
 The male of I. collaris has long legs (i.e. the length of Haller’s organ exceeds the maximum diameter of tarsus I), unlike the male of I. simplex. The palpi of I. collaris male have convexly curved lateral and medial edges, unlike the males of I. ariadnae (where the lateral edge is straight) and I. simplex (where the lateral edge is bent at an angle). The palpal setae are long (up to 210 µm), unlike in the males of I. ariadnae (30–100 µm) and I. simplex (20–80 µm). The most important features to distinguish males of I. collaris from those of I. vespertilionis are on the gnathosoma: (i) more elongated palpi (length to breadth ratio 2.52 vs 2.0–2.1) (Fig. 1d vs 1c); (ii) the sparse distribution and low number (<10) of long anterior and lateral palpal setae, which show dense distribution and higher number (> 20) in I. vespertilionis (Fig. 1c); and (iii) the posteriorly diverging (trapezoid), sclerotized ridge dorsally on the basis capituli, which is much less conspicuous and posteriorly converging (U-shaped) in I. vespertilionis (Fig. 1c). In addition, (iv) the idiosoma of male I. collaris is more elongated than the idiosoma of male I. vespertilionis (length to breadth ratio 1.61 vs 1.35, Fig. 1b vs 1a) and (v) ventrally the ivory coloration anterior to the anus is oval, elongated in I. collaris, whereas this is less apparent in I. vespertilionis (Fig. 2c).   
 The larva of I. collaris has long legs, unlike the larva of I. simplex (in which the legs are short, i.e. the length of Haller’s organ does not exceed the maximum diameter of tarsus I). The palpi of I. collaris larva are elongated, club-shaped, with a length to breadth ratio above three (length × width: 240 × 70 µm), unlike in I. vespertilionis (Fig. 6a: club shaped, but shorter, 200 × 70 µm), I. ariadnae (shorter and broader, 200 × 90 µm, laterally straight) and I. simplex (shorter and narrower, 140 × 60 µm). The scutum of I. collaris larva is longer than broad, pentagonal, with long cervical grooves, ending at the deepest point of the concavely curved posterolateral margin of scutum (unlike in case of I. ariadnae and I. simplex). The most important features to distinguish the larva of I. collaris from that of I. vespertilionis can be observed ventrally on the basis capituli: (i) its caudolateral edge is strongly concave in case of I. collaris, showing perpendicular angle at the concavity, whereas it is only slightly concave, with an obtuse angle, in I. vespertilionis (Fig. 6a); and (ii) at/behind the maximum breadth of ventral basis, the presence of a conspicuous, long, dark sclerotized edge (“collar”) also makes I. collaris larvae different from I. vespertilionis larvae, where this structure is less apparent (Fig. 6b vs 6a). In addition, (iii) caudal setae on the idiosoma are considerably longer than 100 µm in I. collaris larvae, unlike in I. vespertilionis larvae (≤ 100 µm, see Figs. 4a and 6c); and (iv) the medial edge of coxa I is much shorter than that of coxa II in I. vespertilionis larvae (Fig. 6c), as contrasted to I. collaris larvae.
description: Published as part of Hornok, Sándor, Murányi, Dávid, Kontschán, Jenő & Tu, Vuong Tan, 2019, Description of the male and the larva of IxodES CollarIS Hornok, 2016 with drawings of all stages, pp. 1-8 in Parasites & Vectors (144) (144) 12 (1) on pages 3-5, DOI: 10.1186/s13071-019-3365-3, http://zenodo.org/record/11074624