Hygrobates (Lurchibates) fragmentarius, Goldschmidt & Nishikawa & Hiruta & Pfingstl & Jiang & Shimano, 2021

Goldschmidt, Tom, Nishikawa, Kanto, Hiruta, Shimpei F., Pfingstl, Tobias, Jiang, Jian-Ping & Shimano, Satoshi, 2021, Systematics, distribution and morphology of the newt parasitic water mites of the subgenus Lurchibates Goldschmidt & Fu, 2011 (Acari, Hydrachnidia Hygrobatidae, Hygrobates Koch, 1837), including the description of four new species and a key to all so far known species, Zootaxa 4985 (1), pp. 1-36 : 14-15

Hygrobates (Lurchibates) fragmentarius sp. nov. Goldschmidt, Nishikawa & Shimano

Unfortunately the only specimen of this new species is severely damaged, nevertheless the few morphological data as well as the molecular information (28S) clearly demonstrate that it’s a new species. Even though, a complete species description is not possible, we are giving all available information here.

Material examined: Fragment of unknown sex, slide mounted in glycerine jelly, preparation no. CIB INV 0026, parasitic on Paramesotriton yunwuensis ( Amphibia, Caudata , Salamandridae ); newt was collected in China, Guangdong (mite was collected from unnumbered voucher specimen stored in the CIB collection, without detailed geographic information) preserved in 70% ethanol; mite was attached to the groin of the newt.

Distribution: The only specimen of H. fragmentarius sp. nov. was collected from Paramesotriton yunwuensis . The new species is probably limited to the same distribution as its host, southwestern Guangdong Province, China ( Wu et al., 2010).

Derivatio nominis: fragmentarius (Latin = fragmented, fragmentary); referring to the poor condition of the only available specimen.

Diagnosis: Anterior coxal group very slender; gnathosoma anterior heavily curved; palp strong and slender; P-4 relatively slender, proximo-ventral extension of P-5 large, blunt cone-shaped; cheliceral claw relatively curved.

Description, Sex unknown (n = 1): Idiosoma heavily damaged; fused anterior coxae of both sides elongated, triangular, Cx-I + II L/W 366/492, ratio 0.74, medio-posterior margin clearly extended by secondary sclerotization, posteriorly narrow rounded, postero-lateral extension slightly hook-shaped, Cx-I basal width 122, ratio Cx-I L/Cx-I basal width 3.0; gnathosoma anteriorly heavily curved, rounded tips far projecting, lateral margin with Cx-I posteriorly clearly converging, connection with posterior part of Cx-I narrow; gnathosoma and Cx-I anteriorly separated by deep indentation ( Fig. 41 ); chelicerae strong; cheliceral claws very large, curved, distally sharply pointed, dorsal margin in the distal half with strong serration that continues proximally in a lateral serration, medially and laterally striated, basal part with long ventral groove ( Figs. 42, 43 ); palps strong, relatively slender ( Fig. 44 ), ventral margin of P-2 straight, without denticles, P-3 ventrally straight with field of denticles in distal 2/3, P-4 relatively long and slender, slightly curved, with a pair of ventral setae in the distal fourth; P-5 with a blunt, cone-shaped ventro-proximal projection, dorso-distally with a compact, denticle-like distal claw, distally with a pair of large, strong, similar, ventrally curved claws; mouthpart measurements: Chelicera L 442, H 122, basal segment L 287, claw L 202, curvation of cheliceral claw 26°; palp total L 556, L/H P-1 52/69, P-2 148 /96, P-3 110/63, P-4 194/61, P-5 52/54.

Remarks on the new species described above: Hygrobates (Lurchibates) macrochela sp. nov. and H. (L.) malosimilis sp. nov. are very similar in the shape of the palp and especially the very characteristic heavy, distally thickened cheliceral claw, separating them from all other Lurchibates species ( Figs. 7–10 , 16–19 , 26–29 ). They are clearly separated from each other in the shape of the male genital field: Wider in H. (L.) macrochela ( Fig. 1 ), rather narrow in H. (L.) malosimilis ( Fig. 20 ); and the shape of the anterior coxal group: Slightly more slender in H. (L.) macrochela , wider in H. (L.) malosimilis (Cx-I L/basal W 1.5 –1.8 in H. (L.) macrochela , 1.9 in H. (L.) malosimilis ; Cx-I+II L/ W 0.67 –0.75 in H. (L.) macrochela , 0.81 in H. (L.) malosimilis ). The narrow anterior coxal group ( Fig. 20 ) is as well separating H. (L.) malosimilis from all other species of the subgenus (Cx-I+II L/ W 0.81 in H. (L.) malosimilis , 0.62–0.77 in all other species).

Hygrobates (Lurchibates) incognitus sp. nov. unfortunately so far is only known in the female, nevertheless the species can clearly be separated from the other known species of Lurchibates by the shape of their mouthparts and genital field: H. (L.) incognitus is bearing a relatively slender, “normal” palp (P-4 L/H 2.8–3.3), whereas H. (L.) salamandrarum (P-4 L/H 2.1) and H. (L.) robustipalpis (P-4 L/H 2.5–2.6) are characterized by rather compact palps; H. (L.) ancistrophorus has a unique palp with P-5 missing the ventro-distal cone which is present in all other species of the subgenus. H. (L.) incognitus has large and strongly curved cheliceral claws, but these are not distally thickened, as they are in H. (L.) macrochela and H. (L.) malosimilis ; Furthermore the cheliceral claw is relatively straight (claw curve 19–21°) in H. (L.) aloisii , H. (L.) intermedius and H. (L.) forcipifer , as well as in H. (L.) macrochela and H. (L.) malosimilis , whereas the cheliceral claw is more curved (claw curve 26–27°) in H. (L.) incognitus , H. (L.) pilosus ( Figs. 36, 37 ) and H. (L.) fragmentarius sp. nov. ( Figs. 42, 43 ). Moreover, in H. (L.) incognitus the acetabular plates are rather kidney-shaped, small, posteriorly not extending beyond the post-genital sclerite, the arrangement of the acetabula is rather triangular (Ac-3 beside Ac-2), there are three to four setae laying free in the integument antero-medial to the acetabular plates ( Fig. 30 ); in contrast, in females of H. (L.) macrochela the crescent-shaped acetabular plates are slightly extending beyond the post-genital sclerite, the acetabula are forming an arc (Ac-3 clearly posterior to Ac-2), there are no setae antero-medial to the acetabular plates ( Fig. 11 ); in H. (L.) pilosus and H. (L.) forcipifer the acetabular plates are as well not reaching beyond the post-genital sclerite, but in these species the acetabula are rather forming an arc; in H. (L.) aloisii and H. (L.) intermedius the acetabular plates are – as in H. (L.) incognitus – rather kidney-shaped, small, but they are shifted posteriorly, at least reaching the posterior end of the post-genital sclerite.

Even though the only specimen of Hygrobates (Lurchibates) fragmentarius sp. nov. is heavily broken and fragmented, the species is clearly separated from all other so far known species of the subgenus by very long and slender gnathosoma and anterior coxae ( Fig. 41 ), especially Cx-I is basally very narrow (Cx-I L/basal W 3.0 vs. 1.5–2.8 in other species); the palps are slender, especially P-3 (L/H 1.8 vs. 0.9–1.4 in all other species).

Figures

Figure 11. Hygrobates (Lurchibates) macrochela sp. nov., paratype female, ventral view of idiosoma; scale bar = 100 µm.

FIGURE 30. Hygrobates (Lurchibates) incognitus sp. nov., holotype female, ventral view of idiosoma; scale bar = 100 µm.

FIGURES 41–44. Hygrobates (Lurchibates) fragmentarius sp. nov., Fig. 41. ventral view of gnathosoma and right Cx-I,-II; Fig. 42. right chelicera in lateral view; Fig. 43. left chelicera in medial view; Fig. 44. left palp in medial view; scale bars = 100 µm.

FIGURES 3–10. Hygrobates (Lurchibates) macrochela sp. nov., holotype male, Fig. 3. I-leg, right; Fig. 4. II-leg, right; Fig. 5. III-leg, right; Fig. 6. IV-leg, right; Fig. 7. left chelicera in medial view; Fig. 8. right chelicera in lateral view; Fig. 9. left palp in medial view; Fig. 10. right palp in lateral view (P-1 missing); scale bar = 100 µm.

FIGURES 12–19. Hygrobates (Lurchibates) macrochela sp. nov., paratype female, Fig. 12. I-leg, right; Fig. 13. II-leg, right; Fig. 14. III-leg, right; Fig. 15. IV-leg (terminal segment separated), right; Fig. 16. left chelicera in lateral view; Fig. 17. right chelicera in medial view (slightly broken); Fig. 18. left palp in lateral view; Fig. 19. right palp in medial view; scale bar = 100 µm.

FIGURES 22–29. Hygrobates (Lurchibates) malosimilis 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. right chelicera in lateral view; Fig. 27. left chelicera in medial view (partly broken); Fig. 28. left palp in medial view; Fig. 29. right palp in lateral view; scale bars = 100 µm.

FIGURES 1, 2. Hygrobates (Lurchibates) macrochela sp. nov., holotype male, Fig. 1. ventral view of idiosoma; Fig. 2. genital skeleton in anterior view; scale bars = 100 µm.

FIGURES 20, 21. Hygrobates (Lurchibates) malosimilis sp. nov., holotype male, Fig. 20. ventral view of idiosoma; Fig. 21. genital skeleton in anterior view (slightly twisted); scale bars = 100 µm.

FIGURES 31–40. Hygrobates (Lurchibates) incognitus sp. nov., paratype female, Fig. 31. I-leg, left; Fig. 32. II-leg, left; Fig. 33. III-leg, left; Fig. 34. IV-leg-1-4, left; Fig. 35. IV-leg-5, -6, left; Fig. 36. right chelicera in medial view (partly broken); Fig. 37. left chelicera in lateral view (partly broken); Fig. 38. right palp in medial view; Fig. 39. left palp in medial view; Fig. 40. right palp in lateral view; scale bars = 100 µm.