Sinaxonopsis hainanensis, JiaK & LiK & K, 2024

JiaK, Lan, LiK, Hai-Tao & K, Jian-Jun Guo, 2024, Two species representing a rare genus Sinaxonopsis (Acari, Hydrachnidiae, Aturidae) from China, with discussion of some taxonomic features, Acarologia 64 (2), pp. 554-574 : 565-573

publication ID	https://doi.org/ 10.24349/orqe-mqh
publication LSID	lsid:zoobank.org:pub:27F5A3C9-FC58-47CA-AE05-6309DF752E46
persistent identifier	https://treatment.plazi.org/id/03E28502-3822-395E-FE59-FA10FCBAFE16
treatment provided by	Felipe
scientific name	Sinaxonopsis hainanensis
status	sp. nov.

Treatment

Sinaxonopsis hainanensis sp. nov.

Zoobank: 4AB02675-9B86-42FF-87EE-203ABED00AC4

( Figures 13–21 View Figure 13 View Figure 14 View Figure 15 View Figure 16 View Figure 17 View Figure 18 View Figure 19 View Figure 20 View Figure 21 )

Habitat — Stream with numerous rocks and aquatic plants at the bottom ( Figure 13 View Figure 13 ).

Material examined — Holotype: male, Diaoluoshan Nature Reserve , Benhao Town, Lingshui Li Autonomous County, Hainan Province, P. R. China (18°67′08″ N, 109°89′43″ E,

270 m a.s.l.), collected by Hai-Tao Li, Yu-Lin Zheng, and Yu-Hao Zhang, 13-IV-2023. Slides No. HN-AT-2023041301. Paratypes: 3♂, the same data as the holotype, Slide No. HN-AT-2023041302–2023041304; 2♂, 1♀, Qinglv waterfall, Yaga Scenic Area, Bawangling National Nature Reserve, Qicha Town, Changjiang Li Autonomous County, Hainan Province, P. R. China (19°08′48″ N, 109°12′39″ E, 463 m a.s.l.), collected by Hai-Tao Li, Yu-Lin Zheng, and Yu-Hao Zhang, 23-IV-2023. Slides No. HN-AT-2023042301–2023042303.

Diagnosis — Dorsal shield formed by one pair of anterior platelets and a large posterior plate; anterior platelets bearing the lateral eyes, O 2, A 2 and D 1 ; posterior plate bearing six pairs of glandularia, D 2 –D 4, L 2 –L 3 and V 4. Male. Idiosoma blue to purple in color, with an irregular bluish-purple pattern, genital field triangular; genital pore L/W 2.86–3.07; IV-L-5 ventrally with a row of plumose setae; IV-L-6 without distinct processes. Female. Idiosoma brownish to yellow, with an irregular brownish-yellow pattern on the posterior dorsal plate; genital field well developed and placed at the ventral end of the body.

Description — Male (n=6). Idiosoma oval, blue-purple color, slightly truncate at anterior end; dorsal and ventral shields present ( Figures 14 View Figure 14 and 15 View Figure 15 ). In dorsal view ( Figures 14A View Figure 14 , 15A View Figure 15 and 16A View Figure 16 ): dorsal shield formed by one pair of anterior platelets and a large posterior plate; anterior platelets bearing the lateral eyes, O 2, A 2 and D 1 ; posterior plate bearing six pairs of glandularia, D 2 –D 4, L 2 –L 3 and V 4 ( Figure 16A View Figure 16 ), setae of A 2, D 1 –D 3, L 2 –L 3 all far away from

4–6. Scale bars = 100 μm.

glands, numerous longitudinal stripes, and with an irregular bluish-purple pattern, almost 2/3 of the entire large posterior plate ( Figure 15A View Figure 15 ); excretory pore protruding, located at the posterior end of dorsal shield. In ventral view ( Figures 14B View Figure 14 , 15B View Figure 15 and 16B View Figure 16 ): coxal plate single; tips of Cx-I not extending beyond frontal margin; Cx-IV with distinct suture lines, suture line of Cx-III/IV ending medially to IV-L insertions and not reaching the medial line; C 2 located at the posterior margin of Cx-II where suture line of Cx-II/III slightly curved; Cx-IV well extended posteriorly with round posterior margin and laterally with a ridge; basal segmental fossa of IV-L without ankles ( Figure 18A View Figure 18 ). Genital field triangular and slightly depressed, fused to ventral shield; gonopore elongated and somewhat projecting, anteriorly with several genital hairs; multiple acetabula located on both sides of gonopore in the posterolateral area of idiosoma ( Figure 18B View Figure 18 ); C 4 located at either side of posterior part of genital pore.

Gnathosoma with pointed dorsal apodeme, ventral apodeme blunt and almost equal in length; two pairs of setae at the peak of the rostrum ( Figure 18C View Figure 18 ). Chelicera two-segmented; cheliceral claw curved knife shaped ( Figure 1D View Figure 1 ).

Palp five-segmented ( Figures 19A and 19B View Figure 19 ); P-1 dorsally with one seta socket on the outer side, without seta; P-2 with three dorsal setae on the outer, two setae on the inner sides; P-3 short, with two dorsal setae on the outer side; P-4, basally and distally concave on venter, medially convex with a pair of long setae.

Legs six-segmented; ventral margin and dorsal margin of I-L-6 and II-L-6 with a dense patch of small setae ( Figures 20B and 20D View Figure 20 ), claws with one dorsal and one ventral clawlet ( Figures 19C, 19D View Figure 19 and 20 View Figure 20 ); III-L and IV-L exhibiting significant sexual dimorphism; III-L-4 with three large setae on the end of the inner side, two of which are cylindrical; III-L-5 terminally with one ventrally curved large seta on the outer side; III-L-6 without distinct specific setae, with a pair of heteromorphic claws ( Figures 16E View Figure 16 and 21 View Figure 21 ); IV-L-4 with a well-developed projection bearing three large setae on the inner side ( Figure 18E View Figure 18 ), the two last of which are blunt and slightly curved; IV-L-5 ending with one angular projection, ventrally with a row of plumose setae and one large cylindrical seta at the end; IV-L-6 without distinct processes, with a claw same as that of I-L and II-L ( Figures 16F View Figure 16 and 18D View Figure 18 ).

Female (n=1). Characteristics almost similar to male, except for the following: idiosoma brownish to yellow; from the lateral view, the ventral margin of idiosoma slightly projecting ( Figures 14C View Figure 14 and 15D View Figure 15 ); genital field well developed at the ventral end of the body; gonopore large and terminally located ( Figure 15E View Figure 15 ); V 3 positioned further anterior to the genital field; C 4 located anterolateral to the tip of the gonopore ( Figure 17B View Figure 17 ). III-L without heteromorphic setae; claws same as in I-L and II-L ( Figure 17C View Figure 17 ); IV-L-4 ending without prominence, with one long swimming hair; IV-L-5 with one angular prominence at the end, two long swimming setae and one ventrally curved large seta, and one row of tiny setae on venter ( Figure 17D View Figure 17 ).

Measurements — Male (n=6). Idiosoma L/W 508 (478–534)/424 (408–442); anterior platelets L/W 198 (193–214)/73 (70–73), posterior plate L/W 405 (384–425)/388 (384–419);

gnathosomal bay L 142 (137–144); gonopore L/W 71 (68–74)/25 (22–25), ratio 2.86 (2.86–

3.22). gnathosoma vL 129 (125–129), dL 142 (1431–144); chelicera total L 171 (148–171),

claw L 52 (42–52), basal segment L 114 (106–130), L basal segment/claw ratio 2.19 (2.19–3.09). Palp: dL/H, dL/H ratio: P-1, 44 (43–45)/23 (23–24), 1.91 (1.76–1.91); P-2, 79 (76–79)/28

(26–28), 2.73 (2.73–2.99); P-3, 37 (37–46)/23 (23–31), 1.61 (1.30–1.61); P-4, 106 (106–109),

5.91 (5.91–6.02); P-5, 42 (41–42)/11 (11–16), 3.63 (2.70–3.63); Legs: dL of I-L-1–6: 47 (44–

47), 43 (43–53), 67 (67–72), 111 (105–114), 116 (116–140), 128 (128–144); dL of II-L-1–6:

54 (47–55), 62 (49–62), 79 (72–82), 113 (108–125), 144 (135–145), 139 (139–153); dL of

III-L-1–6: 72 (72–82), 53 (53–60), 82 (78–89), 99 (83–99), 151 (151–171), 147 (142–149); dL

of IV-L-1–6: 108 (107–118), 115 (113–118), 185 (179–190), 89 (89–108), 178 (175–191), 145

(134–159).

Female (n=1). Idiosoma L/W 513/422; anterior platelets L/W 204/58, posterior plate L/W 443/394; gnathosomal bay L 151. gnathosoma vL 134, dL 148. Palp: dL of P-1–5, 45, 81, 43,

105, 44; Legs: dL of I-L-1–6: 48, 43, 61, 90, 111, 118; dL of II-L-1–6: 59, 52, 67, 103, 131,

137; dL of III-L-1–6: 55, 56, 69, 109, 124, 129; dL of IV-L-1–6: 93, 73, 97, 103, 137, 121.

Remarks — Due to the morphology of the dorsum (formed by one pair of anterior platelets and a large posterior plate), genital field (with multiple acetabula) and palp (P-4 with a pair of long setae) of the specimens from Hainan, China, the new species, S. hainanensis sp. nov., resembles S. laosensis Pešić & Smit, 2016 from Laos. However, the new species differs from S. laosensis in the following aspects: (1) S. hainanensis sp. nov. (L/W 508 (478–534)/424 (408–

442)) smaller than S. laosensis (L/W 581/443); (2) S. hainanensis sp. nov. body bluish-purple, but colourless in S. laosensis ; (3) IV-L-5 venter with a row of plumose setae in S. hainanensis sp. nov., but only one large pennate seta and two slender setae in S. laosensis .

Etymology — The name “ hainanensis ” refers to the type location, where the specimens were collected.

Distribution — China (Hainan).