Unionicola (Unionicola) maolanensis Ding & Jin, 2019

Ding, Zhuhui, Jin, Daochao, Guo, Jianjun & Yi, Tianci, 2019, Three new species of the subgenus Unionicola Haldeman, 1842 (Acari, Hydrachnidia, Unionicolidae) from Guizhou, China, Zootaxa 4658 (1), pp. 141-154 : 142-146

Unionicola (Unionicola) maolanensis Ding & Jin , sp. nov.

( Figs. 1 , 2 , 3 )

Material examined. Holotype ♀: GZ-UN-2006071509, Maolan National Nature Reserve , Guizhou Province, Chi- na (25°13′48′′ N, 107°53′23′′ E, 1344 m a.s.l.), collected by Jianjun Guo, 15-VII-2006 , Paratype: 3 ♂♂, 2 ♀♀, same data as holotype .

Diagnosis. Dorsum with two pairs of small unequal platelets; excretory pore and L 4 at the same level; P-4 with three slender distoventral projections with the lateral longer than the ventral and subequal with the distal one. Ventral apodeme of infracapitulum caved distally almost as a perpendicular hook. Inner setae on posterior acetabular plates slightly longer than that on anterior acetabular plates in female; I-L-6 with one dorsoproximal heavy seta; II-L-6 laterally with two thick setae.

Description. Female. Integument smooth ( Figs. 1-E ), dorsum with two pairs of platelets in unequal size; anterior platelets located between D 1; excretory pore not well-developed, located at the same level as L 4, V 1 situated distally on dorsal idiosoma. Coxal plates ( Figs. 1-F ) in four groups occupying approximately two-thirds venter, surface lightly reticulated ( Figs. 2-E ); posterior apodemes of ACG extending to the first third of Cx-III; E 2 located close to Cx-II; suture line of Cx-III/IV curved forward and ending nearly at median of Cx-III; posterior projection of Cx-IV short and somewhat hook-like.Acetabular plates terminally located ( Figs. 1-D ) with six pairs of acetabula, anterior plates with two pairs of moderate thick inner setae and two pair anterior fine setae, posterior plates with one pair of longer thick inner setae and four pairs of fine setae. V 4 with well-sclerotized and enlarged gland situated on sides of acetabular plates.

Palp slender ( Figs. 2-F ); P-2 with four peg-like setae, of which the distal one the longest; P-3 with two similar dorsal setae; P-4 with three projections, lateral one slightly longer than proximoventral one and nearly equal to distal one in length, and the two proximal projections each bearing a thin seta; P-5 venter concaved, with one proximal seta. Ventral apodeme of infracapitulum ( Figs. 2-D ) appeared a hook in right-angle bent in lateral view. Chelicera ( Figs. 2-C ) gradually tapering with a well-developed claw.

Leg I–IV showed as Figs. 3 . Leg I the thickest and nearly as long as leg III. I-L-1 with three dorsal awl-shaped setae and one ventrodistal normal seta; I-L-2 distally with one long and one short blunt setae, and one awl-shaped seta, dorsally with six awl-shaped setae; I-L-3 with two ventral blunt setae and four awl-shaped setae; I-L-4 with five blunt setae unequal in length. I-L-5 with five ventral and two distolateral blunt setae; I-L-6 dorsally with one heavy seta, distoventrally with a thick upwardly curved projection; claws of leg I thick and hook-like with two unequal clawlets ( Figs. 3-E ). Leg II slightly shorter than leg IV ( Figs. 3-B ); II-L-2 with one short ventral heavy seta and six dorsal awl-shaped setae; II-L-3 with two lateral, five dorsal awl-shaped setae and one distal heavy seta, ventrally with one swimming seta; II-L-4 ventrally with one blunt seta and one distal heavy seta, laterally with three setae, dorsally with five awl-shaped setae; II-L-5 with two ventral blunt setae, two short heavy setae, two dorsal awl-shaped setae, three distal short swimming setae; II-L-6 laterally with two awl-shaped setae. III-L-1 with three awl-shaped setae ( Figs. 3-C ); III-L-2 with two ventral blunt and two dorsal awl-shaped setae; III-L-3 ventrally with one blunt seta and one swimming seta, dorsally with five awl-shaped setae; III-L-4 with three ventral blunt setae, one lateral slender heavy seta, five dorsal awl-shaped setae and three swimming setae; III-L-5 with four ventral, two lateral, four dorsal setae and three distal swimming setae. IV-L-1 with three dorsal awl-shaped setae and one lateral slender seta ( Figs. 3-D ); IV-L-2 with one distal blunt and four dorsal awl-shaped setae; IV-L-3 laterally with three blunt setae, dorsally with three pairs of awl-shaped setae, and ventrally with three long setae and one distal serrated swimming seta; IV-L-4 ventrally with four blunt setae, laterally with two setae, dorsally with six awl-shaped setae, and distally with two short and three long swimming setae; IV-L-5 with five ventral, two lateral and five dorsal setae, distally with three long swimming setae; IV-L-6 ventrally with two slender heavy setae and dorsodistally with one thick seta. The sixth segments of leg II–IV each distally with one thin curved projection; claws of legs II–IV sickle-shaped and each with a short dorsal and a long ventral clawlet ( Figs. 3-F ).

Measurements (n=3). Idiosoma L/W 667/453–706/472 (ratio 1.47–1.49). Genital field L/W 143/173–146/132 (L/W ratio 1.11–1.33). LA 204–213. LP 247–253. Medial distance between Cx-IV 40–47. Chelicera L 140–150. L of P-1–5: 25–26; 99–101; 53–54; 110–117; 81–83. Lengths of I-L-1–6: 75–77; 198–200; 218–227; 290–297; 186–195; 204–214. Lengths of II-L-1–6: 65–72; 183–197; 222–237; 288–297; 315–324; 257–264. Lengths of III- L-1–6: 67–70; 153–167; 184–189; 203–210; 254–263; 204–214. Lengths of IV-L-1–6: 90–97; 152–180; 207–210; 240–248; 350–356; 314–321.

Male. Idiosoma characters same as the female except: Acetabular plates lunate and anteriorly and posteriorly fused with sclerotized cuticle ( Figs. 1-C ); the anterior three acetabula triangularly arranged, and the posterior three longitudinally in a row on each side of the plate. A pair of long normal setae anteriorly free from the genital field. Each genital plate with ten fine setae, of which two located anteriorly, five laterally, one posteriorly and two medially. Excretory pore close to idiosoma margin.

Measurements (n=3). Idiosoma L/W 514/367–610/500 (ratio 1.22–1.40). Genital field L/W 147/176–193/203 (L/W ratio 0.84–0.95). LA 197–207. LP 223–237. Medial distance between Cx-IV 22–27. Ejaculatory complex L 170–190. Chelicera L 112–132. L of P-1–5: 20–27; 85–100; 45–53; 93–96; 70–78. Lengths of I-L-1–6: 60–66; 130– 160; 163–183; 227–250; 160–178; 169–187. Lengths of II-L-1–6: 51–70; 150–170; 180–202; 250–263; 283–298; 227–247. Lengths of III-L-1–6: 57–63; 118–133; 150–167; 175–198; 225–243; 277–193. Lengths of IV-L-1–6: 80–90; 126–130; 163–187; 210–223; 293–337; 277–296.

Remarks. This new species is similar to U. minor Soar, 1900 . The latter species can be easily separated by its following characters: (1) P-3 with two long setae unequal, while the setae similar in the new species; (2) in projections on P-4, the lateral one longer than the distal one, while almost equal in length in the new species; (3) P-5 with one proximal seta, while without the seta in new species; (4) anterior genital plates of female with long inner setae but unequal in length, while the setae short and almost equal in the new species; (5) although description originally absent in setae on the genital plate, obviously the posterior edge of female genital plates with more than one fine seta from Imamura et al. (1953) and Tuzovskij et al. (2015), while with only one fine posterior seta in the new species; (6) swimming setae on IV-Leg-5 shorter than IV-Leg-6, while they similar in the new species.

Etymology. The species is named after the natural reserve (Maolan) from where it was collected.

Habitat. Reservoir, densely covered with Eichhornia crassipes .

Distribution. China (Guizhou province).

Figures

FIGURE 1. U. maolanensis sp. nov., A–C, male (paratype): A. idiosoma dorsal view; B. idiosoma ventral view; C. genital field. D–F, female (holotype): D. genital field, E. idiosoma dorsal view; F. idiosoma ventral view. Scale bars = 100 μm

FIGURE 2. U. maolanensis sp. nov., A–B, male (paratype): A. palp; B. ejaculatory complex. C–F, female (holotype): C. chelicera; D. infracapitulum; E. mesh pattern of Cx-I. F. palp. Scale bars = 100 μm.

FIGURE 3. U. maolanensis sp. nov., A–D, female (holotype): A. leg I; B. leg II; C. leg III; D. leg IV; E. claws of leg I; F. claws of leg IV. Scale bars = 100 μm.