Walchia lupella ( Traub and Evans, 1957 )

Antonovskaia, Anastasia A., Morand, Serge & Stekolnikov, Alexandr A., 2024, New species and new records of chigger mites (Acariformes, Trombiculidae) from Cambodia, Zootaxa 5406 (2), pp. 343-358 : 354-356

Walchia lupella ( Traub and Evans, 1957)

( Figs. 6C, D , 8 )

Diagnosis. SIF = 4B-N-3-2110.0000; fPp = N/N/NNN; fSc: PL ≥ AL; fCx = 1.1.2; fSt = 2.2; Ip = 504–527; fD = 2H-6-8-6-6(5)-2(3)-2(4)-2(1)-1(0); DS = 43–51; V = 31–36; NDV = 69–87; leg claws equal; nude ventrofemorala III present. Standard measurements are in Table 4 .

Redescription (larva). IDIOSOMA ( Figs. 6C, D , 8B, C, F, G ). Eyes 1+1; 43–51 dorsal idiosomal setae covered with long barbs, including one pair of humeral setae; six setae in 1 st post-humeral row (C excluding humeral setae), 8 setae in 2 nd row (D), 6 setae in 3 rd row (E), 6 (rarely 5) setae in 4 th row (F); distribution of setae by posterior rows unclear; 4 sternal setae; 31–36 ventral setae; total number of idiosomal setae excluding coxal and sternal 69–87.

GNATHOSOMA ( Figs. 8D, E ). Cheliceral blade with tricuspid cap; gnathobase, cheliceral base, and palpal femur sparsely covered with puncta; gnathobase with one pair of branched gnathocoxal (tritorostral) setae; galeal (deutorostral) seta nude; palpal claw with three prongs; setae on palpal femur, genu, and tibia nude; palpal tarsus with four branched setae and basal tarsala (ω).

SCUTUM (6C, 8A). Pentagonal, longer than width, densely covered with puncta; posterior scutal margin sharply angulate; ALs and PLs situated on scutal projections; SB situated far anterior to level of PLs, at almost equal distances from ALs and PLs; PL> AL; scutal setae barbed similarly to dorsal idiosomal setae; clavate sensilla moderately covered with setules.

LEGS (8H–J). Anterior legs seven-segmented, middle and posterior six-segmented (with undivided femur). Legs with one pair of equally thick claws and thin claw-like empodium. Leg I: coxa with 1 non-specialized branched seta (1B); trochanter 1B; basifemur 1B; telofemur 5B; genu 4B, 2 genualae (σ), microgenuala (κ); tibia 7B, 2 tibialae (φ) in tandem, distal tibiala rod-like, striated, proximal tibiala setiform, microtibiala (κ) at level of distal tibiala; tarsus 22B, tarsala (ω) 13–16 long, microtarsala (famulus, ε) posterior to tarsala, subterminala (ζ), parasubterminala (z), pretarsala (ζ). Leg II: coxa 1B; trochanter 1B; femur 6B; genu 3B, genuala (σ); tibia 6B, 2 tibialae (φ) in tandem, distal tibiala rod-like, striated, proximal tibiala setiform; tarsus 16B, tarsala (ω) 11 long, microtarsala (famulus, ε) behind tarsala, pretarsala (ζ). Leg III: coxa 2B; trochanter 1B; femur 4B, nude ventrofemorala; genu 3B, genuala (σ); tibia 6B; tarsus 15B.

Distribution and hosts. This mite species was originally described from Thailand ( Traub & Evans 1957); later on, it was found in China ( Wen 1984b), India ( Fernandes & Kulkarni 2003), Indonesia ( Goff & Durden 1987), Laos ( Vercammen-Grandjean 1971; Kumlert et al. 2018), Vietnam ( Hadi & Carney 1977; Antonovskaia et al. 2017) and finally in Cambodia (this study). This species was recorded on 17 species of rodents, one treeshrew, one gymnure, two shrews, one bat, one mongoose, and hen ( Stekolnikov 2021).

Material examined. Two larvae ( ZIN 14234 , 14236 ) ex B. savilei No. C 0683, CAMBODIA, Mondulkiri Province, Keo Seima , 23 November 2009 ; two larvae ( ZIN 9823 , 9824 ) ex Rattus tanezumi Temminck No N 053, N031, THAILAND, Nakhon Sawan, 29 April 2013, coll. K. Chaisiri.

Remarks. Stekolnikov (2021) provided a bibliography and the full list of hosts for this species. Its original description as Gahrliepia (Walchia) ewingi lupella was brief and included only a differential diagnosis, table of measurements, and figures of scutum, gnathosoma, leg claws, and leg coxa III ( Traub & Evans 1957). Vercammen-Grandjean (1971) elevated this subspecies to the species rank and provided its redescription. However, the redescription included some differences from the original description, first the presence of two pairs of eyes vs. one pair. The leg claws were redescribed as uneven, with smaller claw “inconspicuously thinner than the empodium”, whereas according to the figure in the original description, both claws are equal and much thicker than the empodium. Traub & Evans (1957) did not describe the arrangement of dorsal idiosomal setae in G. (W.) ewingi lupella ; thus, it could probably be the same as in G. (W.) ewingi ewingi (Fuller, 1949) , i.e. fD = 2H-6-6-6-6-4-2, with some variation, whereas the re-description gave 2H-6-6-8-6-6-4-4.

Vercammen-Grandjean (1971) did not discuss these differences and did not state whether his redescription was based on the W. lupella type series. Therefore, it could be based, by mistake, on a material of another species. Our material appears to be more consistent with the original description, than to the redescription. Fernandes & Kulkarni (2003) redescribed W. lupella based on the reference data and a new material from India. Their drawing (fig. 166) shows two pairs of eyes as in the redescription by Vercammen-Grandjean (1971), which contradicts the original description and our data. Currently, we do not have opportunity to examine the holotype of W. lupella , which is deposited in the National Museum of Natural History (Washington, D.C., US); thus, our identification is provisional.

Figures

FIGURE 6. Walchia keoseima sp. nov., holotype. A—anterior part of idiosoma, dorsal aspect; B—sternal area. Walchia lupella (Traub and Evans, 1957), specimen ZIN 9823. C—anterior part of idiosoma, dorsal aspect; D—sternal area. Scale bars: 100 µm.

FIGURE 8. Walchia lupella (Traub and Evans, 1957), specimens ZIN 9823 (A–C, F–J), ZIN 9824 (D), ZIN 14236 (E). A—scutum (eyes not figured); B—humeral seta; C—preanal seta; D—ventral aspect of gnathosoma; E—dorsal aspect of gnathosoma; F—arrangement of dorsal idiosomal setae; G—arrangement of ventral idiosomal setae; H—leg I; I—leg II; J—leg III. Abbreviations: vf—ventrofemorala; other abbreviations as in Figures 2 and 3. Scale bars: 50 μm (A–C), 20 μm (D, E), 100 μm (F, G), 100 μm (I–K).