Eutrombicula gonzalezi Stekolnikov, 2022

Stekolnikov, Alexandr A., Capek, Miroslav & Literák, Ivan, 2022, New species and records of chiggers (Acariformes: Trombiculidae) from birds of the Neotropics, Zootaxa 5141 (6), pp. 501-552 : 514-517

Eutrombicula gonzalezi Stekolnikov sp. nov.

( Figs. 7–9 )

Diagnosis. SIF = 7BS-N-2-3111.1000; fsp = 7.7.7; fCx = 1.1.1; fSt = 2.2; fPp = B/B/NNB; fSc: PL> AL> AM; Ip = 954–1003; fD = 2H-6-6-4-2(2-4)-(0–2); DS = 20–22; V = 10–12; NDV = 32. Inner prong of palpal claw significantly shorter that outer prong; scutal and dorsal idiosomal setae thin and sparsely covered with short appressed barbs; scutum nearly pentagonal, covered with puncta of different size, without transverse striae; sensilla (trichobothria) with ca. 7–9 branches in distal half; sensillary bases anterior to level of PL (PSB—P-PL = 4–11 µm). Standard measurements of type series given in Table 4 .

Description (larva) (based on holotype and 9 paratypes). IDIOSOMA ( Figs. 7 , 8A–F ). Eyes 2 + 2; 20–22 dorsal idiosomal setae, including one pair of humeral setae, thin and sparsely covered with short appressed barbs, by 6 setae in 1 st and 2 nd (D) posthumeral rows, 4 setae in 3 rd (E) row, 2 setae in 4 th (F) row (setae in rows E and F can be also counted as 2-4); 2 more caudal setae can be counted among ventral setae; arrangement of setae in holotype 2H-6-6-4-2; 4 sternal setae; 10–12 ventral setae; NDV = 32 (no variation recorded).

GNATHOSOMA ( Fig. 8G, H ). Cheliceral blade with tricuspid cap; cheliceral base with small dense puncta basally and more sparse puncta in distal part; gnathobase with small puncta, transverse striae, and 1 pair of branched gnathocoxal (tritorostral) setae; galeal (deutorostral) seta nude; palpal claw with 2 prongs, inner prong significantly shorter that outer prong; palpal femur with sparse puncta different by size, with branched seta; palpal genu with puncta and branched seta; dorsal and lateral palpal tibial setae nude, ventral palpal tibial seta branched; palpal tarsus with 7 branched setae, nude subterminala (ζ) and basal tarsala (ω).

SCUTUM ( Figs. 7C , 8A ). Nearly pentagonal, covered with puncta of two types: 1) of moderate size, sparsely covering all scutal surface, 2) very small, forming dense groups in some parts of scutum; anterolateral shoulders small, anterior scutal margin lightly sinuous, lateral margins concave, posterior margin angulate; AM at level of AL, sensillary (trichobothrial) bases anterior to level of PL ( PSB —P-PL = 4–11 µm); all scutal setae uniform with dorsal idiosomal setae; PL > AL> AM; flagelliform sensilla (trichobothria), with ca. 7–9 branches in distal half .

LEGS ( Fig. 9 ). All 7-segmented, with 1 pair of claws and claw-like empodium. Leg I: coxa with 1 branched seta (1B); trochanter 1B; basifemur 1B; telofemur 5B; genu 4B, 3 genualae (σ), microgenuala (κ); tibia 8B, 2 tibialae (φ), microtibiala (κ); tarsus 22B, tarsala (ω), microtarsala (ε) distal to tarsala, subterminala (ζ), parasubterminala (z), pretarsala (ζ). Leg II: coxa 1B; trochanter 1B; basifemur 2B; telofemur 4B; genu 3B, genuala; tibia 6B, 2 tibialae (φ); tarsus 16B, tarsala (ω), microtarsala (ε) proximal to tarsala, pretarsala (ζ). Leg III: coxa 1B; trochanter 1B; basifemur 2B; telofemur 3B; genu 3B, genuala; tibia 6B, tibiala; tarsus 14B, mastitarsala.

Hosts . Myiophobus fasciatus , Turdus albicollis , Schiffornis virescens .

Type material. Holotype larva ( ZIN 8940 ) ex T. albicollis No PG 212, PARAGUAY: San Rafael National Park , Kanguery, 22 August 2012 . Paratypes: 9 larvae ( ZIN 8941–8949 ) with same data ; 3 larvae ( ZIN 8905–8907 ) ex S. virescens No PG 52 and 2 larvae ( ZIN 8983 , 8984 ) ex M. fasciatus No PG 248, Kanguery, 19 and 24 August 2012, respectively .

Etymology. The species is named after Dr. Daniel González-Acuña (1963–2020), a Chilean parasitologist who made an important contribution to the chigger studies in South America.

Differential diagnosis. Eutrombicula gonzalezi sp. nov. is similar to E. picunche Stekolnikov and González-Acuña, 2015 described from a single specimen (holotype) collected from a lizard in Chile, in having the shape of scutum and setation of palps and idiosoma similar, but differs from it by the relatively shorter inner prong of palpal claw, the presence of nude mastitarsala (vs. ciliated), larger scutum ( PW = 88–100 vs. 72, SD = 56–64 vs. 53) with more prominent posterior margin ( PSB = 29–34 vs. 22, P-PL = 21–29 vs. 17), longer setae (e.g. AM = 30–36, AL = 35–41, PL = 56–63, and V min = 38–43 vs. 23, 23, 35, and 29, respectively), and much longer legs (Ip = 954–1003 vs. 720) .

Figures

FIGURE 7. Eutrombicula gonzalezi sp. nov., paratype ZIN 8907 (one leg III and one sensillum broken). A—general view, B—dorsal aspect of idiosoma, C—scutum, D—ventral aspect of idiosoma. Scale bars: 100 µm (A), 50 µm (B–D).

FIGURE 8. Eutrombicula gonzalezi sp. nov. A—scutum and eyes (paratype ZIN 8941), B—ventral idiosomal seta (holotype), C—dorsal idiosomal seta (holotype), D—humeral seta (holotype), E—dorsal aspect of idiosoma (holotype), F—ventral aspect of idiosoma (holotype), G—ventral aspect of gnathosoma (holotype), H—dorsal aspect of gnathosoma (holotype). Abbreviations as in Fig. 2. Scale bars: 50 µm (A), 20 µm (B–D, G, H), 100 µm (E, F).

FIGURE 9. Eutrombicula gonzalezi sp. nov., holotype. A—leg I (genu–tarsus), B—leg I (trochanter–telofemur), C—leg II (trochanter–tarsus), D—leg III (trochanter–tarsus). Abbreviations as in Fig. 3.