Eutrombicula helleri ( Oudemans, 1911 )

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 : 522-525

Eutrombicula helleri ( Oudemans, 1911)

( Figs. 13–15 )

Microthrombidium helleri Oudemans, 1911: 120 ; 1912: 15, fig. C.

Eutrombicula helleri: Fuller 1952: 139 .

Diagnosis. SIF = 7BS-N-2-3111.1000; fsp = 7.7.7; fCx = 1.1.1; fSt = 2.2; fPp = B/N(B)/NNN; fSc: PL> AM> AL; Ip = 812–934; fD = 2H-6-6-4-2-(0-2); DS = 19–22; V = 10–14; NDV = 32–35. Inner prong of palpal claw twice as short as outer prong and located medially on the latter; scutal and dorsal idiosomal setae thin, moderately covered with short barbs; scutum nearly pentagonal, with small dense puncta and transverse striae; sensilla (trichobothria) with ca. 8–10 branches in distal half; sensillary bases far anterior to level of PL (PSB—P-PL = 9–14 µm). Standard measurements of examined specimens given in Table 5 .

Redescription (larva) (based on 21 specimens). IDIOSOMA ( Figs. 13 , 14A–G ). Eyes 2 + 2; 19–22 dorsal idiosomal setae, including one pair of humeral setae, moderately covered with short 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, 5 th (H) row includes 2 setae (half of specimens), 1 (one specimen) or absent; 4 sternal setae; 10–14 ventral setae; NDV = 32–35.

GNATHOSOMA ( Fig. 14H, I ). Cheliceral blade with tricuspid cap; cheliceral base with small dense puncta basally and more sparse puncta in distal part; gnathobase with small dense puncta, transverse striae, and 1 pair of branched gnathocoxal (tritorostral) setae; galeal (deutorostral) seta nude; palpal claw with 2 prongs, inner prong twice as short as outer prong and located medially on the latter; palpal femur with puncta and branched seta; palpal genu with puncta and nude seta (having 1–2 branches in two specimens); palpal tibia with three nude setae; palpal tarsus with 7 branched setae, nude subterminala (ζ) and basal tarsala (ω).

SCUTUM ( Figs. 13C , 14A, B ). Nearly pentagonal, densely covered with small puncta, with transverse striae, with small anterolateral shoulders, anterior scutal margin lightly sinuous, lateral margins concave, posterior margin broadly rounded; AM at level of AL, sensillary (trichobothrial) bases far anterior to level of PL (PSB—P-PL = 9–14 µm); all scutal setae uniform with dorsal idiosomal setae; PL> AM> AL; flagelliform sensilla (trichobothria), with ca. 8–10 branches in distal half.

LEGS ( Fig. 15 ). 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.

Distribution. Surinam, Panama ( Fuller 1952), Paraguay, and Peru (this study).

Hosts . Arthropoda: Passalus sp. ( Coleoptera : Passalidae ); Reptilia: Ameiva praesignis (Baird and Girard) ( Squamata : Teiidae ); Mammalia: Didelphis marsupialis L. ( Didelphimorphia : Didelphidae ), Dasyprocta punctata (Gray) ( Rodentia : Dasyproctidae ), “rat” ( Rodentia : Muridae ), Homo sapiens L. ( Primates : Hominidae ), Sylvilagus brasiliensis gabbi (J. Allen) (= S. gabbi ) ( Lagomorpha : Leporidae ), Leopardus pardalis (L.) (= Felis pardalis ) ( Carnivora : Felidae ); Aves: Gallus gallus domesticus (L.) ( Galliformes : Phasianidae ), Leptotila verreauxi ( Columbiformes : Columbidae ), Tyrannidae gen. sp. ( Fuller 1952).

New host records: Campylorhamphus trochilirostris , Cantorchilus guarayanus , Casiornis rufus , Glyphorynchus spirurus , Gymnopithys leucaspis , Lepidocolaptes angustirostris , Leptotila rufaxilla , Myiarchus tyrannulus , Paroaria capitata , Microspingus melanoleucus , Ramphocaenus melanurus , Saltator coerulescens , Taraba major , Thamnophilus doliatus , Thamnophilus schistaceus , Troglodytes aedon , Turdus amaurochalinus , Turdus rufiventris .

Material examined. Three larvae ( ZIN 9111–9113) ex C. trochilirostris No PG 400, 1 larva ( ZIN 9130 ) ex C. rufus No PG 444 , 4 larvae ( ZIN 9020 , 9034 , 9134 , 9135 ) ex L. angustirostris Nos PG 328, PG345, PG446 , 2 larvae ( ZIN 9035 , 9137 ) ex M. tyrannulus Nos PG 346 and PG456 , 1 larva ( ZIN 9117 ) ex P. capitata No PG 440 , one larva ( ZIN 9115 ) ex M. melanoleucus No PG 431 , 3 larvae ( ZIN 9098 , 9128 , 9150 ) ex S. coerulescens Nos PG 376, PG443, PG473 , 9 larvae ( ZIN 9049–9057 ) ex T. major No PG 367 , 4 larvae ( ZIN 9103 , 9106–9108 ) ex T. doliatus No PG 394 , 15 larvae ( ZIN 9021–9023 , 9038–9041 , 9092–9097 , 9120 , 9133 ) ex T. aedon Nos PG 337, PG363, PG372, PG442, PG445 , 6 larvae ( ZIN 9079–9081 , 9083 , 9088 , 9089 ) ex C. guarayanus Nos PG 370 and PG371 , 8 larvae ( ZIN 9018 , 9019 , 9042–9047 ) ex T. amaurochalinus Nos PG 326 and PG366 , 7 larvae ( ZIN 9058–9064 ) ex T. rufiventris No PG 368, PARAGUAY: Tres Gigantes Biological Station , 6–9 September 2012 ; 2 larvae ( ZIN 8831 , 8832 ) ex T. schistaceus No TR 2 , 8 larvae ( ZIN 8833–8840 ) ex R. melanurus No TR 5, PERU: San Martin Province, Tarapoto, Centro URKU, 8 August 2011 ; 18 larvae ( ZIN 8841–8858 ) ex G. leucaspis Nos IQ 1 and IQ2 , 1 larva ( ZIN 8876 ) ex L. rufaxilla No IQ 33 , 2 larvae ex G. spirurus Nos IQ 32 and IQ5, PERU: Iquitos, National Reserve Allpahuayo Mishana , 13–16 August 2011 .

Variation. Specimens from Paraguay slightly differ from specimens collected in Peru by the shape of scutum and sparser scutal puncta ( Fig. 14A, B ). According to the results of Mann-Whitney test, measurements characterizing width (AW, PW) and length (ASB, PSB, SD, AP) of the scutum were significantly higher in the sample from Paraguay ( Table 6 ), whereas the length of humeral setae (H) was lesser in these specimens.

Remarks. Eutrombicula helleri differs from E. goeldii by significantly shorter setae (AM–V max in Table 5 ), shorter legs (pa–TaIIIL), and longer relative distance of mastitarsala from the base of leg tarsus III (m-t). The posterior scutal margin of E. goeldii is straight in the middle part and obliquely cut at the edges, whereas in E. helleri it is evenly arquate, bow-shaped (compare Fig. 11A and 14A, B ). Scutal puncta are denser in E. goeldii than in E. helleri . Intervals of all scutal measurements for these species overlap, but differences in some of these characters are statistically significant. Thus, E. helleri has the scutum narrower (lesser AW and PW), ASB and AP lesser, and P-PL greater than those features in E. goeldii ( Table 5 ).

Figures

FIGURE 11. Eutrombicula goeldii (Oudemans, 1910). A—scutum and eyes (specimen ZIN 8829), B—dorsal idiosomal seta (specimen ZIN 8829), C—ventral idiosomal seta (specimen ZIN 8829), D—ventral aspect of idiosoma (specimen ZIN 8830), E—dorsal aspect of idiosoma (specimen ZIN 8830), F—ventral aspect of gnathosoma (specimen ZIN 8829), G—dorsal aspect of gnathosoma (specimen ZIN 8829). Abbreviations as in Fig. 2. Scale bars: 50 µm (A), 20 µm (B, C, F, G), 100 µm (D, E).

FIGURE 13. Eutrombicula helleri (Oudemans, 1911)—specimen ZIN 8852, Peru. 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 14. Eutrombicula helleri (Oudemans, 1911). A—scutum and eyes (specimen ZIN 9103, Paraguay), B—scutum and eyes (specimen ZIN 8841, Peru), C—ventral aspect of idiosoma (specimen ZIN 8852, Peru), D—dorsal aspect of idiosoma (specimen ZIN 8852, Peru), E—humeral seta (specimen ZIN 8852, Peru), F—dorsal idiosomal seta (specimen ZIN 8852, Peru), G—ventral idiosomal seta (specimen ZIN 8852, Peru), H—dorsal aspect of gnathosoma (specimen ZIN 8852, Peru), I—ventral aspect of gnathosoma (specimen ZIN 8852, Peru). Abbreviations as in Fig. 2. Scale bars: 50 µm (A, B), 100 µm (C, D), 20 µm (E–I).

FIGURE 15. Eutrombicula helleri (Oudemans, 1911), specimen ZIN 8852, Peru. A—leg I (trochanter–tarsus), B—leg II (trochanter–tarsus), C—leg III (trochanter–tarsus). Abbreviations as in Fig. 3.