Hygrobates robustipalpis, Goldschmidt & Nishikawa & Hiruta & Shimano, 2020

Goldschmidt, Tom, Nishikawa, Kanto, Hiruta, Shimpei F. & Shimano, Satoshi, 2020, Description of three new water mite species of Hygrobates Koch, 1837 (Lurchibates Goldschmidt & Fu, 2011) (Acari, Hydrachnidia, Hygrobatidae), parasitic in newts of the genera Paramesotriton and Pachytriton (Amphibia, Caudata, Salamandridae) from China, Zootaxa 4768 (1), pp. 25-42 : 31-35

Hygrobates robustipalpis sp. nov. Goldschmidt, Nishikawa & Shimano

Material examined: Holotype male, slide mounted in glycerine jelly, preparation no. CIB INV 0004, parasitic on Pachytriton inexpectatus ( Amphibia, Caudata , Salamandridae ): newt was collected in China, Guizhou Province, Leishan County, Mt. Leigong on September 24th 2011, preserved in 70% Ethanol; mite was attached to the fore- or hindlimb of the newt ( CIB GZ 20110948).

Paratypes: two females CIB INV 0005 from mouth cavity, limbs, or lateral body of the newt ( CIB GZ 20110947) and CIB INV 0006 from mouth cavity, axilla, groin (base of the hindlimb), or lateral body of the newt ( CIB GZ 20110948), one male CIB INV 0007 from mouth cavity, limbs, or lateral body of the newt ( CIB GZ 20110947)— newts data are the same as holotype’s host.

Distribution: All specimens of H. robustipalpis sp. nov. have been collected from Pachytriton inexpectatus from Guizhou Province, China. The new species is at maximum limited to the same distribution as its host, which is so far known from Eastern Guizhou, southwestern and southern Hunan, extreme northwestern Guangdong, and northern and eastern Guangxi, China.

Derivatio nominis: robustipalpis —derived from robustus (lat.)—strong, powerful; palpus (lat.)—palp; named for the very strong and pointed basal cone and the long and pointed terminal claws at P-5.

Diagnosis: Characters of the subgenus; idiosoma relatively small, coxal field relatively broad (compared to most other species of the group), anterior coxal group posteriorly broad; male genital field rounded, apple-shaped, with many setae regularly arranged at outer margin; female genital plates broad kidney-shaped, larger than genital opening, shifted posteriorly; distal leg segments relatively shorter than in other species; P-2 ventro-distally bearing a few denticles, P-3 ventro-distally bearing many denticles, P-4 relatively compact, proximo-ventral extension of P-5 large, pointed, tip slightly curved ventrally; cheliceral claw relatively straight, long and slender.

Description, Male (n = 2): Idiosoma rounded-oval, L/W ratio 1.12 (1.13), L/W 672 (636)/600 (564); fused anterior coxae of both sides slender, narrow triangular (Cx-I + II L/W 294 (277)/462 (402)), medio-posterior margin extended by secondary sclerotization (posteriorly convex, laterally curved, pointed); Cx-I basal width 176 (153), gnathosoma broad, posteriorly slightly converging, lateral separation reaching far posteriorly, widely fused with the posterior part of the first coxae, anterior tip of gnathosoma slightly projecting ( Fig. 20 ); posterior coxal groups (Cx- III + Cx-IV of one side) L/W 247 (228)/252 (197), anterior and posterior coxal groups laterally very close, medially diverging (however, less than given in Fig. 20 , as in the type-specimen the integument is broken and the posterior coxal groups are slightly shifted to lateral as an artifact); posterior coxae obtuse triangular medial edges rounded, formed by Cx-IV only, Cx-IV short and broad, trapezoid, posterior margin straight transversely, lateral margin straight ( Fig. 20 ); genital field rounded apple-shaped, acetabular plates anteriorly and posteriorly overlapping the pre- and postgenitale, with 24/27 (27/30) setae regularly arranged at outer margin on each side ( Fig. 20 ), genital opening elongate-oval, genital field L/W 192 (144)/ 296 (258); acetabula irregularly elongated oval (L/W Ac-1, 104 (57)/49 (36), Ac-2, 98 (83)/48 (39), Ac-3, 98 (60)/42 (43)); genital skeleton partly broken in type specimen (completely destroyed in second specimen), as far as visible shape typical for the subgenus, brachia distalia very long and slender, regularly curved ( Fig. 21 ); all legs slender, bearing many heavy setae, dorso-distally at I- and II-leg-1 and -2 with groups of four to six heavy setae, distal segments straight ( Figs. 22–25 ); measurements (L/H) of distal leg segments: I-leg-5, 234 (210)/48 (48), I-leg-6, 192 (192)/48 (46); II-leg-5, 234 (228)/48 (48), II-leg-6, 198 (198)/48 (42); III-leg-5, 258 (252)/50 (48), III-leg-6, 222 (216)/54 (48); IV-leg-3, 168 (156)/66 (58), IV-leg-5, 270 (258)/ 54 (48), IV-leg-6, 234 (223)/48 (42); chelicerae very strong, with a relatively short, high basal segment and long basal groove; cheliceral claws large (slightly shorter than in other species), slender, distally straight, sharply pointed, dorsal margin in the distal half with strong serration that continues proximally in a lateral serration, medially and laterally striated ( Figs. 26, 27 ); palps strong ( Figs. 28, 29 ), ventral margin of P-2 slightly concave, antero-ventral corner bearing a few denticles, P-3 ventro-laterally with many large, pointed denticles in distal 2/3, P-4 compact, straight, distally slightly curved, with a pair of ventral setae in the distal third, distal margin strongly rotated ventrally; P-5 ventro-proximally bearing a well developed, pointed, cone-shaped projection, with a ventrally-curved, sharp tip, dorso-distal seta compact, denticle-like, sticking out, ventro-distal pair of large claws long and pointed; mouthpart measurements: chelicera total L 372 (353), maximum H 102 (102), L/H ratio 3.7 (3.5), basal segment L 235 (216), claw L 183 (167), basal segment/claw ratio 1.3 (1.3); curvation of cheliceral claw 22° (23.5°), palp total L 451 (423), L/H P-1, 52 (42)/73 (68), P-2, 127 (115)/85 (85), P-3, 80 (80)/78 (75), P-4, 146 (139)/59 (52), P-5, 47 (47)/54 (47).

Description, Female (n = 2): Idiosoma similar to male, much larger, L/W 816–1380/684–1296, and more rounded (L/W ratio 1.06–1.19); unpaired anterior coxal group as in males, L/W 312–336/462–486, medio- and latero-posterior margin extended by secondary sclerotization, with slightly curved lateral tips; Cx-I basal width 186–193; gnathosoma anteriorly more curved, slightly more projecting than in males, separation to Cx-I posteriorly converging, reaching far posteriorly (as in males) ( Fig. 30 ); paired posterior coxal groups closer to each other and to the anterior coxal group than in males, more slender, posterior margin inclined from postero-lateral to antero- medial, triangular in shape with medial edges formed by Cx-IV only, L/W 270–294/252–259 ( Fig. 30 ); genital field relatively wide and large (broader than in males), with strongly sclerotized pre- and postgenitale, genital plates well distant from each other, posteriorly by far more approached than anteriorly, separated by soft integument, broad kidney-shaped, anteriorly rounded, clearly longer than genital opening, level of anterior margin lightly posterior to pregenitale, posterior margin extending far beyond postgenitale ( Fig. 30 ), total genital field L/W 204–282/318–366; acetabula irregularly-oval (some rather triangular or rectangular) (L/W Ac-1, 79–85/42, Ac-2, 91–98/44–46, Ac- 3, 86–95/45–49); 21–26 setae arranged mainly at the anterior, posterior and lateral margins of the genital plates, one or two pairs anterior to genital plates ( Fig. 30 ); legs similar to males ( Figs. 31–34 ) measurements of distal leg segments: L/H I-leg-5, 238–240/49–50, I-leg-6, 204–216/48; II-leg-5, 252–262/54–55, II-leg-6, 216–222/46–55; III-leg-5, 283–284/54–55, III-leg-6, 235–242/48–54; IV-leg-3, 180–198/62–68, IV-leg-5, 294–300/54–58, IV-leg- 6, 240–264/42–54; chelicerae similar to males, slightly stronger ( Figs. 35, 36 ); palps similar to males ( Figs. 37, 38 ); mouthpart measurements: chelicera total L 420–432, maximum H 120–124, L/H ratio 3.5, basal segment L 268–277, claw L 198–209, basal segment/claw ratio 1.3–1.4; cheliceral claw curve 21–22°; palp total L 479–498, L/H P-1, 52–54/80, P-2, 132–139/87–94, P-3, 94–99/82–85, P-4, 153–155/59–61, P-5, 49–52/59–61.

Figures

FIGURE 30. Hygrobates robustipalpis sp. nov., paratype female, ventral view of idiosoma; scale bar = 100 μm.

FIGURES 20–21. Hygrobates robustipalpis sp. nov., holotype male, Fig. 20. ventral view of idiosoma, Fig. 21. genital skeleton in anterior view; scale bar = 100 μm.

FIGURES 22–29. Hygrobates robustipalpis sp. nov., holotype male, Fig. 22. I-leg, right, Fig. 23. II-leg, right, Fig. 24. III-leg, right, Fig. 25. IV-leg, right, Fig. 26. left chelicera in lateral view, Fig. 27. right chelicera in medial view, Fig. 28. left palp in medial view, Fig. 29. right palp in lateral view; scale bar = 100 μm.

FIGURES 31–38. Hygrobates robustipalpis sp. nov., paratype female, Fig. 31. I-leg, left, Fig. 32. II-leg, left, Fig. 33. III-leg, left, Fig. 34. IV-leg, left, Fig. 35. left chelicera in medial view, Fig. 36. right chelicera in lateral view, Fig. 37. right palp in medial view, Fig. 38. left palp in lateral view; scale bar = 100 μm.