Atractides (Atractides) cardiacus Zhang & Guo 2025, sp. nov.
Creators: name: Zhang, Yu-Hao
name: Li, Hai-Tao
name: Hu, Zhan-Yu
name: Guo, Jian-Jun
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Trombidiformes
Hygrobatidae
Atractides
Atractides cardiacus

description: Atractides (Atractides) cardiacus Zhang & Guo sp. nov.
urn:lsid:zoobank.org:act: FFFC2C6D-4E4C-4610-B34B-25D21B7D3942
Figs 1–15, 25
Diagnosis
Male
Apodemes of ACG curved hook-shaped, and posterior margin of Cx-IV almost straight. Anterior margin of genital plate slightly indented, posterior margin slightly convex, three pairs of acetabula forming an obtuse triangle. V 1 separated from V 2, excretory pore smooth. Sword seta on P-4 at same level of proximoventral hair. I-L-6 thick at base, tapering distally.
Female
Similar to male. Ac in weakly curved line, Ac2 at middle of Ac1 and Ac3. Palp more slender than in male.
Etymology
The new species is named after the heart-like genital plate of the male.
Type material
Holotype P.R. CHINA • ♂; Hainan Province, Qionghai City, Longjiang Town; 19.1730° N, 110.3459° E; 4 m a.s.l.; 11 Apr. 2023; Hai-Tao Li, Yu-Lin Zheng and Yu-Hao Zhang leg.; main river (Wanquan River) with wide surface, slowly flowing, with sandy soil and humus on bottom; slide no. HN-HY-2023041101; GUGC.
Paratypes P.R. CHINA • 3 ♂♂, 3 ♀♀; same data as for holotype; slides nos. HN-HY-2023041102 to 2023041107; GUGC.
Description
Male (n = 4)
Idiosoma soft and oval; O 1 between A 1 and A 2, but closer to A 1, O 2 between D 1 and at same level of D 1; all slit organs visible, So 1 near A 2, So 2 at same level of D 1 and O 2, So 3 at same level of D 2, So 4 close to L 4, So 5 behind of D 4 (Figs 2A, 6A). ACG fused together and with suture line, apodemes of ACG curved hook shape; PCG separated, posterior margin of Cx-IV almost straight, C 4 near suture line between Cx-III and Cx-IV, suture line of Cx-III and Cx-IV in medial part nearly straight (Fig. 8A). Anterior margin of genital plate slightly indented, posterior margin slightly convex, three pairs of acetabula forming obtuse triangle, Ac2 near Ac1 (Fig. 9D). V 1 separated from V 2, V 2 posterior to V 1 (Fig. 8B), V 4 at same level of Ac2, V 3 and V 4 arranged in inverted trapezoid; excretory pore smooth and between V 2 (Figs 2B, 6B).
Palp five-segmented, without obvious sexual dimorphism; P-1 short, P-2 and P-3 short with straight ventral margin, P-4 with some dorsal hairs and two ventral hairs, dividing P- 4 in sectors 3:2:2, sword seta at same level of proximoventral hair (Figs 2C, 9A–B). Ventral margin of I-L-5 slightly longer than dorsal margin, S-1 close to S-2 and S-2 thickens at three-fifth position and then narrows immediately, whip-like seta at anterior distal margin; I-L-6 thick at base, distally tapering. IV-L-5 with swimming seta at distal margin and almost as long as IV-L-6 (Figs 3, 10).
MEASUREMENTS (measurements of paratypes in parentheses). Idiosoma L 450 (420–460), W 385 (371– 386); coxal field L 245 (216–245), Cx-III W 263 (238–263), ACG IL 180 (163–180), mL 116 (112–123), W 192 (183–192); gnathosoma bay L 83 (68–83); genital field L 81 (70–82), W 109 (92–109); Ac1–3
L 20 (19–21), 22 (20–22), 24 (21–24); chelicera L 166 (155–171), cheliceral claw L 43 (42–47), basal segment L 126 (123–138); gnathosoma L 136 (131–139); palp dL: P-1 22 (19–22), P-2 51 (48–54), P-3 49 (45–50), P-4 73 (67–74), P-5 27 (24–28); leg segments: I-L-1 dL 39 (36–41), I-L-2 dL 66 (65–73), I-L-3 dL 80 (74–84), I-L-4 dL 125 (115–128), I-L-5 dL 117 (103–117), HB 37 (33–37), I-L-6 dL 65 (65–73), HB 15 (11–15), S-1 L 61 (57–61), W 6 (5–6), S-2 L 57 (55–59), W 7 (6–8); dL: II-L-1 39 (37– 43), II-L-2 62 (55–71), II-L-3 68 (60–69), II-L-4 89 (76–90), II-L-5 98 (86–104), II-L-6 85 (82–91); dL: III-L-1 42 (36–46), III-L-2 62 (61–66), III-L-3 67 (64–69), III-L-4 96 (87–96), III-L-5 112 (101–112), III-L-6 108 (95–108); dL: IV-L-1 88 (78–88), IV-L-2 85 (71–85), IV-L-3 106 (102–109), IV-L-4 122 (118–127), IV-L-5 137 (125–139), IV-L-6 134 (118–134).
Female (n = 3)
Similar to male. Ac in weakly curved line, Ac2 at middle of Ac1 and Ac3, V 3 at same level of pregenital sclerite, distance between pregenital sclerite and postgenital sclerite longer, V 3 and V 4 arranged in trapezoid; excretory pore slightly posterior to level of V 2. Palp more slender than in male (Figs 4–5, 7, 12–15).
MEASUREMENTS (measurements of paratypes in parentheses). Idiosoma L 783 (722–807), W 621 (621– 678); coxal field L 254 (254–293), Cx-III W 327 (327–363),ACG IL 176 (176–212), mL 101 (101–115), W 223 (223–259); gnathosoma bay L 97 (97–120); gonopore L 141 (99–141), pregenital sclerite L 79 (61–79), postgenital sclerite L 37 (33–40); Ac1–3 L 22 (22–26), 28 (23–28), 25 (25–28); chelicera L 219 (219–240), cheliceral claw L 58 (58–66), basal segment L 175 (175–186); gnathosoma L 146 (146–184); palp dL: P-1 26 (25–26), P-2 64 (64–77), P-3 65 (65–74), P-4 85 (85–96), P-5 31 (31–34);
leg segments: I-L-1 dL 43 (43–48), I-L-2 dL 80 (80–92), I-L-3 dL 95 (95–104), I-L-4 dL 148 (148–168), I-L-5 dL 131 (131–143), HB 44 (44–49), I-L-6 dL 78 (77–85), HB 12 (11–13), S-1 L 63 (63–71), W 6 (6–7), S-2 L 59 (59–68), W 8 (8–10); dL: II-L-1 48 (48–56), II-L-2 70 (70–88), II-L-3 78 (78–87), II-L-4 107 (107–116), II-L-5 115 (115–126), II-L-6 94 (94–104); dL: III-L-1 48 (48–57), III-L-2 71 (71–91), III-L-3 79 (79–87), III-L-4 109 (109–125), III-L-5 125 (125–140), III-L-6 109 (109–122); dL: IV-L-1 87 (87–106), IV-L-2 84 (84–98), IV-L-3 121 (121–133), IV-L-4 146 (146–163), IV-L-5 156 (156–177), IV-L-6 151 (151–154).
Remarks
The new species Atractides (Atractides) cardiacus Zhang & Guo sp. nov. is similar to Atractides putihi Wiles, 1991 in the following points: (1) the posterior margin of Cx-IV almost straight; (2) V 1 separated from V 2; (3) excretory pore smooth. But A. (A.) cardiacus differs from A. putihi in the following points: (1) the posterior margin of the new species genital field is narrow, but wider in A. putihi; (2) the gonopore of the male new species is short but longer in A. putihi (Pešić & Smit 2009).
description: Published as part of Zhang, Yu-Hao, Li, Hai-Tao, Hu, Zhan-Yu & Guo, Jian-Jun, 2025, Two new species in the genus Atractides Koch, 1837 (Acari: Hydrachnidiae: Hygrobatidae), with the first descriptions of the female of two species from China, pp. 47-76 in European Journal of Taxonomy 976 on pages 49-57, DOI: 10.5852/ejt.2025.976.2775, http://zenodo.org/record/14771799