Walchia delicatula (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960)

Antonovskaia, Anastasia A. & Stekolnikov, Alexandr A., 2021, Redescriptions of ten chigger mite species (Acariformes: Trombiculidae) from Vietnam, Zootaxa 4969 (1), pp. 1-53 : 11-14

Walchia delicatula (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960)

( Figs. 1C, D , 5–7 )

Gahrliepia (Walchia) delicatula Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960c: 470 , figs. 46–53.

Gahrliepia (Walchia) delicatula: Chau et al. 2007: 167 , fig. 82.

Walchia (Walchia) delicatula: Vercammen-Grandjean 1968: 111 .

Walchia delicatula: Kudryashova 2004: 45 .

Walchia tianguangshanensis Zhao, 1981: 324 , figs. 1–5, syn. nov.

Diagnosis. SIF = 4B-N-3-2110.0000; fsp = 7.6.6; fCx = 1.1.1; fSt = 2.2; fPp = N/N/NNN; fSc: AL> PL; Ip = 552–639; fD = 2H-6-6-6-6-4-3-2; DS = 31–38; V = 38–49; NDV = 69–87. Eyes 2 + 2. Standard measurements of type series given in Table 3 .

Description (larva) [based on lectotype and 11 paralectotypes]. IDIOSOMA ( Figs. 1C, D , 5 ). Eyes 2 + 2, posterior pair smaller; 31–38 barbed dorsal idiosomal setae including one pair of humeral setae; 4 sternal setae; 38–49 ventral setae; NDV = 69–87.

GNATHOSOMA ( Fig. 6A, B ). Cheliceral blade with tricuspid cap; cheliceral base moderately covered with puncta; gnathobase with dense puncta and 1 pair of branched setae; galeala nude; palpal claw with 3 prongs; setae on palpal femur, genu, and tibia nude; palpal tarsus with 4 branched setae and tarsala.

SCUTUM ( Fig. 1C ). Pentagonal, longer than width, with pointed posterior angle, densely covered with small puncta, with 1 pair of ALs and 1 pair of PLs; sensilla fusiform, covered with spikes; sensillum bases situated at equal distances from levels of ALs and PLs.

LEGS ( Fig. 6C–E ). All with 1 pair of claws and claw-like empodium. Leg I: 7-segmented, coxa with 1 branched seta (1B); trochanter 1B; basifemur 1B; telofemur 5B; genu 4B, 2 genualae, microgenuala; tibia 8B, 2 tibialae, microtibiala; tarsus 22B, tarsala, microtarsala proximal to tarsala, subterminala, parasubterminala, pretarsala. Leg II: 6-segmented, coxa 1B; trochanter 1B; femur 6B; genu 3B, genuala; tibia 6B, 2 tibialae; tarsus 16B, tarsala, microtarsala near and proximal to tarsala, pretarsala. Leg III: 6-segmented, coxa 1B; trochanter 1B; femur 4B, nude ventral femorala; genu 3B, genuala; tibia 6B; tarsus 15B.

Hosts. Tupaia hongaensis (nomen nudum) ( Scandentia : Tupaiidae ), Rattus norvegicus , Rhizomys pruinosus ( Schluger et al. 1960c) , Rattus tanezumi (= R. flavipectus ) ( Chau et al. 2007), Berylmys bowersi (this study).

Distribution. China (this study), Vietnam.

Type material examined ( Fig. 7 ). Lectotype (here designated): larva ZMMU Tdt-3240 (specimen 3) ex R. pruinosus No 208, Vietnam, Ha Giang Province, Ha Giang, 19 May 1956, coll. I.M. Grochovskaja. Paralectotypes: seven larvae, ZMMU Tdt-3237 (specimen 3), ZMMU Tdt-3238 (specimens 2, 3), ZMMU Tdt-3239 (specimen 2), ZMMU Tdt-3240 (specimen 5), ZMMU Tdt-3241 (specimen 3), ZMMU Tdt-3242 (specimen 3), same collection data as for lectotype; five larvae, ZMMU Tdt-3234 (specimens 1, 2, 4), ZMMU Tdt-3236 (specimens 2, 5), ex R. pruinosus No 258, Vietnam, Ha Giang Province, Ha Giang, 3 June 1956, coll. I.M. Grochovskaja.

Remarks. According to the original description, W. delicatula is similar to W. neosinensis ( Hsu and Wen, 1956) , but differs in the “shape of trichobothria (sensilla), position of seta on leg coxa III, nude outer lateral seta on palpal tibia, wider scutum, and other characters” ( Schluger et al. 1960c). The “outer lateral seta on palpal tibia” is actually ventral palpal tibial seta. The difference in its shape (fPp = N/N/NNN in W. delicatula and fPp = N/N/NNB in W. neosinensis ) is the most clear difference between these two species. We did not find the difference between these species in the position of coxal seta III. The difference in the shape of sensilla (narrower in W. delicatula than in W. neosinensis ) seems reliable, although rather slight. According to our data, the metric differences between these species are as follows: AW = 41–49, PW = 52–69, SB = 34–45, ASB = 22–31, SD = 83–99, and AP = 42–52 in the type series of W. delicatula vs. 33, 41, 29, 20, 82, and 38 in W. neosinensis , respectively ( Hsu & Wen 1956; Li et al. 1997).

The species W. tianguangshanensis Zhao, 1981 , which was described from a single specimen ex B. bowersi from Guangdong Province of China, does not differ from W. delicatula , neither by morphology, nor by measurements ( Table 2 ), and therefore is synonymized here with the latter.

Specimens Nos 1 and 2 on the slide ZMMU Tdt-3237 belong to Walchia pacifica (Chen and Hsu, 1955) .

Figures

FIGURE 1. Gahrliepia mirabilis Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960, lectotype. A, dorsal aspect of body; B, ventral aspect of body. Walchia delicatula (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960), lectotype. C, dorsal aspect of idiosoma; D, ventral aspect of idiosoma. Scale bars: 100 μm.

FIGURE 5. Walchia delicatula (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960). A, arrangement of dorsal idiosomal setae of paralectotype ZMMU Tdt-3239 (specimen 2); B, arrangement of ventral idiosomal setae of paralectotype ZMMU Tdt-3239 (specimen 2); C, dorsal idiosomal seta of 1st row of paralectotype ZMMU Tdt-3238 (specimen 2); D, preanal seta of paralectotype ZMMU Tdt-3238 (specimen 2). Scale bars: 100 μm (A, B), 20 μm (C, D).

FIGURE 6. Walchia delicatula (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960). A, ventral aspect of gnathosoma of paralectotype ZMMU Tdt-3238 (specimen 2); B, dorsal aspect of gnathosoma of paralectotype ZMMU Tdt-3238 (specimen 2); C, leg I (trochanter–tarsus) of paralectotype ZMMU Tdt-3239 (specimen 2); D, leg II (trochanter–tarsus) of paralectotype ZMMU Tdt-3239 (specimen 2); E, leg III (trochanter–tarsus) of paralectotype ZMMU Tdt-3239 (specimen 2). Scale bars: 20 μm (A, B), 50 μm (C–E).

FIGURE 7. Type specimens of Walchia delicatula (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1960) on slides.