Microtrombicula vitosa ( Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963 )

Antonovskaia, Anastasia A. & Stekolnikov, Alexandr A., 2021, Redescriptions of ten chigger mite species (Acariformes: Trombiculidae) from Vietnam, Zootaxa 4969 (1), pp. 1-53 : 46-50

Microtrombicula vitosa ( Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963)

( Figs. 31C, D , 35–37 )

Trombicula vitosa Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963: 694 , figs. 16–22.

Microtrombicula (Microtrombicula) vitosa: Wen 1984: 315 ; Li et al. 1997: 277, fig. 2-10-11; Chau et al. 2007: 98, fig. 46.

Diagnosis. SIF = 4B1b1N-N-2-3111.1000; fsp = 7.7.7; fCx = 1.1.1; fSt = 2.2; fPp = B/B/BNB; fSc: PL> AM = AL; Ip = 585–636; fD = 2H-6-6-4-5-5; DS = 24–28; V = 25–31; NDV = 49–58. Sensilla branched; sternal setae nude; coxal setae I with 1 short cilium; coxal setae II and III nude. Standard measurements of type series given in Table 11 .

Description (larva) [based on lectotype and 7 paralectotypes]. IDIOSOMA ( Figs. 31C, D , 35 ). Eyes 2 + 2; 24–28 barbed dorsal idiosomal setae, including one pair of humeral setae; 4 nude sternal setae; 25–31 ventral setae, nude or having few inconspicuous cilia; NDV = 49–58.

GNATHOSOMA ( Fig. 36A, B ). Cheliceral blade with tricuspid cap; gnathobase with sparse puncta and 1 pair of branched setae; cheliceral base with sparse puncta; galeala nude; palpal claw with 2 prongs, internal prong longer; setae on palpal femur and genu with few short barbs, dorsal palpal tibial seta with few short barbs, lateral palpal tibial seta nude, ventral palpal tibial setae with few branches; palpal tarsus with 4 branched setae, 1 seta with single branch, 1 nude seta and tarsala.

SCUTUM ( Figs. 31C , 36C ). Pentagonal, wider than long, with anterolateral shoulders, with rounded posterior margin, densely covered with small puncta, with 1 AM, 1 pair of ALs and 1 pair of PLs; AM anterior to level of ALs; all scutal setae uniformly barbed; PLs longest scutal setae, ALs and AM of about equal length; sensilla flagelliform, slightly expanded, with 8 long branches in distal half; sensillum bases situated close to each other and far anterior to level of PLs (PSB – P-PL = 9–14 µm).

LEGS ( Fig. 36D–F ). All 7-segmented, with 1 pair of claws and claw-like empodium. Leg I: coxa with 1 seta bearing 1 short cilium (1b); trochanter with 1 branched seta (1B); basifemur 1B; telofemur 5B; genu 4B, 3 genualae, microgenuala; tibia 8B, 2 tibialae, microtibiala; tarsus 22B, tarsala, microtarsala at level of tarsala, subterminala, parasubterminala, pretarsala. Leg II: coxa with 1 nude seta (1N); trochanter 1B; basifemur 2B; telofemur 4B; genu 3B, genuala; tibia 6B, 2 tibialae; tarsus 16B, tarsala, microtarsala at level of tarsala, pretarsala. Leg III: coxa 1N; trochanter 1B; basifemur 2B; telofemur 3B; genu 3B, genuala; tibia 6B, tibiala; tarsus 13B, mastitarsala.

Hosts. Rattus tanezumi Temminck [= Rattus flavipectus (Milne-Edwards) ]. The host was indicated as “rat” on the slide labels but was identified as R. flavipectus in the thesis of Grochovskaja (unpublished typescript).

Distribution. China (Wen 1984; Li et al. 1997), Vietnam.

Type material examined ( Fig. 37 ). Lectotype (here designated): larva ZMMU Tdt-3280 “ Trombicula vitosa -5” (specimen 2) ex R. tanezumi (labeled as “rat”) No 568, Vietnam, Nghe An Province, Phu Quy, 10 September 1956, coll. I.M. Grochovskaja. Paralectotypes: four larvae, ZMMU Tdt-3280 “ Trombicula vitosa ” (specimen 2), ZMMU Tdt-3280 “ Trombicula vitosa -2” (specimen 1), ZMMU Tdt-3280 “ Trombicula vitosa -3” (specimen 5), ZMMU Tdt-3280 “ Trombicula vitosa -4” (specimen 1), same collection data as for lectotype; three larvae, ZMMU Tdt- 3281 “ Trombicula vitosa ” (specimens 1, 2), ZMMU Tdt-3281 “ Trombicula vitosa -2” (specimen 3) ex R. tanezumi (labeled as “rat”) No 577, Vietnam, Nghe An Province, Phu Quy, 11 September 1956, coll. I.M. Grochovskaja.

Remarks. This species is similar to M. spicea (Gater, 1932) by the presence of slightly expanded sensilla, but differs by the nude lateral palpal tibial seta (fPp = B/B/BNB vs. B/B/BBB), 7-segmented legs (fsp = 7.7.7 vs. 7.6.6), longer scutum (SD = 46–48 vs. 41–42), and longer legs (Ip = 585–636 vs. 516–534) ( Vercammen-Grandjean 1965a).

As Vercammen-Grandjean (1965a) noted for M. spicea , the presence of slightly expanded sensilla relates this species to the genus Ascoschoengastia from the tribe Schoengastiini . Probably, Kudryashova (2004) did not list M. vitosa in the catalogue of types because of the uncertainty of the taxonomic position of this species.

Figures

FIGURE 31. Microtrombicula fulgida (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963), lectotype. A, anterior part of idiosoma, dorsal aspect; B, anterior part of idiosoma, ventral aspect. Microtrombicula vitosa (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963), paralectotype ZMMU Tdt-3281 (specimen 1). C, anterior part of idiosoma, dorsal aspect; D, anterior part of idiosoma, ventral aspect. Scale bars: 100 μm.

FIGURE 35. Microtrombicula vitosa (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963). A, arrangement of dorsal idiosomal setae of paralectotype ZMMU Tdt-3281 “Trombicula vitosa-2” (specimen 3); B, arrangement of ventral idiosomal setae of paralectotype ZMMU Tdt-3281 “Trombicula vitosa-2” (specimen 3); C, dorsal idiosomal seta of 1st row of lectotype; D, coxal seta I of paralectotype ZMMU Tdt-3280 “Trombicula vitosa-2” (specimen 1); E, coxal seta II of paralectotype ZMMU Tdt-3280 “Trombicula vitosa-2” (specimen 1); F, coxal seta III of paralectotype ZMMU Tdt-3280 “Trombicula vitosa-2” (specimen 1); G, anterior sternal seta of lectotype; H, posterior sternal seta of lectotype; I, preanal seta of lectotype. Scale bars: 100 μm (A, B), 20 μm (C–I).

FIGURE 36. Microtrombicula vitosa (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963), lectotype. A, dorsal aspect of gnathosoma; B, ventral aspect of gnathosoma; C, scutum and eyes (right sensillum and branches of left sensillum missing); D, leg I (trochanter–tarsus); E, leg II (trochanter–tarsus); F, leg III (trochanter–tarsus) (mastitarsala broken). Scale bars: 20 μm (A, B), 50 μm (C), 50 μm (D–F).

FIGURE 37. Type specimens of Microtrombicula vitosa (Schluger, Grochovskaja, Ngu, Hoe and Tung, 1963) on slides.

Tables

TABLE 11. Standard measurements (µm) and numbers of setae of Microtrombicula vitosa (n = 8).

	Range	Mean	Lectotype
AW	45–49	47	45
PW	53–58	57	58
SB	15–18	17	17
ASB	22–23	22	22
PSB	24–26	24	24
SD	46–48	47	47
P-PL	11–15	13	14
AP	22–26	24	24
AM	25–28	27	26
AL	25–27	26	26
PL	33–37	35	34
H	36–49	39	49
D min	23–27	25	26
D max	27–34	30	31
V min	14–18	17	14
V max	20–29	24	27
pa	199–222	213	207
pm	171–198	181	178
pp	203–225	212	203
Ip	585–636	606	589
DS	24–28	25	25
V	25–31	29	31
NDV	49–58	54	56