Introduction

Most larvae in the family Erythraeidae Robineau-Desvoidy, 1828 are ectoparasites of arthropods and some could be potential vectors of pathogens or biological control agents of hosts (DiBlasi et al., 2011; González-Moraga et al., 2015; Welbourn, 1983). This family belongs to the order Trombidiformes Reuter, 1909 and comprises 66 genera, including Leptus Latreille, 1796 with approximately 275 species described worldwide (Mąkol & Wohltmann, 2012). In Brazil, larval stages of Leptus spp. have been recorded from species of the following arthropod orders: Opiliones; Araneae (Actinopodidae); Coleoptera (Chrysomelidae and Lycidae); Heteroptera (Lygaeidae, Pentatomidae and Reduviidae); Hymenoptera (Apidae); and Diptera (Sarcophagidae) (see Oudemans, 1905, Haitlinger, 1987, 1991; Coracini & Samuels, 2002; Teixeira, 2011; Pereira et al., 2012; Pinto et al., 2014; Martin & Correia-Oliveira, 2016; Salvatierra & Almeida, 2017).

Thirteen species of Leptus have been recorded from Brazil. One species, Leptus (Leptus) calvescens (Berlese, 1888), is only known from the free-living/predatory post-larval instar; the remaining 12 species are only known from the larval instar: L. (L.) adaminae Haitlinger, 2004; L. (L.) alberti Haitlinger, 1991; L. (L.) brasilicus Haitlinger, Šundić & Pompermaier, 2017; L. (L.) candangus Šundić, Haitlinger & Pompermaier, 2017; L. (L.) cyryli Haitlinger, 1991; L. (L.) fozicus Haitlinger, 2004; L. (L.) iguacuicus Haitlinger, 2004; L. (L.) mariani Haitlinger, 1991; L. (L.) onnae Haitlinger, 2000; L. (L.) planaltensis Haitlinger, Šundić & Pompermaier, 2017; L. (L.) stieglmayri Oudemans, 1905); and L. (L.) stolae Haitlinger, 1987 (Haitlinger, 1987, 1991, 2000a, 2004; Haitlinger & Šundić 2016; Haitlinger et al., 2017; Mąkol & Wohltmann 2012; Šundić et al., 2017).

Here we describe a new species of Leptus found on horse flies (Diptera: Tabanidae), collected in two municipalities in the State of São Paulo, Brazil and provide a key for identification of the larvae of Leptus spp. in Brazil.

Materials and methods

Parasitic larval erythraeids collected from horse flies (Diptera: Tabanidae), deposited in the Acari Collection of the Butantan Institute, São Paulo, Brazil (IBSP), were examined. The alcohol fixed specimens were slide-mounted in Hoyer’s medium according to Walter & Krantz (2009). In addition, some old slide mounted specimens in the same collection, were remounted using the technique described by Jacinavicius et al. (2013).

The mites were examined using two microscopy techniques: phase contrast (PC) and differential interference contrast (DIC) microscopy. The specimens were illustrated and measured using a Leica DFC 500 digital camera coupled to a Leica DM4000B phase contrast microscope with a drawing tube and a Leica DFC310 FX digital camera coupled to a Leica DMi8 differential interference contrast inverted microscope. The images were edited by Inkscape V. 2 and Adobe Photoshop v.13.0. All measurements are given in micrometres as the range followed by the mean in parentheses.

The terminology and measurements generally follows Robaux (1974), Southcott (1992), Haitlinger (1999, 2013) and Haitlinger et al. (2017) with additional data from the leg solenidia. We also followed the terminology proposed by Grandjean (1935, 1947) for leg chaetotaxy, and we adopted the nomenclature proposed by Kethley (1990). For L. (L.) nikanori and L. (L.) mariani we used the comparative morphometric data by Mayoral & Barranco (2011) and Haitlinger & Šundić (2016), respectively.

Hosts collected between the years 1938 and 1940 are housed at the Entomological Collection of the Butantan Institute, São Paulo, Brazil (IBSP). These specimens were identified as belonging to Fidena and their taxonomic status was confirmed to the subgenus level Fidena (Fidena) spp. based on Coscarón & Papavero (2009).

Family Erythraeidae Robineau-Desvoidy, 1828

Genus Leptus Latreille, 1796


Leptus ( Leptus ) haitlingeri Jacinavicius, Bassini-Silva & Welbourn n. sp.


Type-host: Fidena (Fidena) sp. (Diptera: Tabanidae), horsefly.

Type-locality: Serra da Cantareira, São Paulo municipality, São Paulo State, Brazil.

Type-material: The holotype and 7 paratypes (all larval) from Fidena (Fidena) sp. (Diptera: Tabanidae) were deposited in the IBSP (reg. no. IBSP1830 - IBSP1835). Hosts were deposited in the Entomological Collection of Butantan Institute (reg. no. IBSP 3266, IBSP 3267, IBSP 3271, IBSP 3273, IBSP 3281 and IBSP 3291), 18.i.1940, coll. Fonseca.

Additional material examined: One larva of the same host species (host reg. no. IBSP 2725), same locality, 13.iii.1939, coll. Fonseca; mite deposited in the IBSP (reg. no. IBSP 1642); 3 larvae of the same host species (host reg. no. IBSP 2726 - IBSP 2728), same locality, 03.ii.1939, coll. Fonseca; all mite specimens deposited in the IBSP (reg. no. IBSP1643, IBSP1644 and IBSP1646); 1 larva of the same host species (host reg. no. IBSP 2729), same locality, 7.ii.1939, coll. Fonseca; mite deposited in the IBSP (reg. no. IBSP 1651); 12 larvae of the same host species (host reg. no. IBSP 3239, IBSP 3269, IBSP 3270, IBSP 3272, IBSP 3277, IBSP 3282, IBSP 3284–IBSP3286 and IBSP 3294), same locality, 20.i.1940, coll. Fonseca; all mite specimens deposited in the IBSP (reg. no. IBSP1837–IBSP 1846); 10 larvae of the same host species (host reg. no. IBSP 3268, IBSP 3274, IBSP 3276 and IBSP 329), same locality, 27.i.1940, coll. Fonseca; all mite specimens deposited in the IBSP (reg. no. IBSP1847–IBSP1849, IBSP1851, IBSP1852, IBSP1855 and IBSP1857); 1 larva of the same host species (host reg. no. IBSP 2630), Brazil, São Paulo state, Ribeirão Preto municipality, Fazenda Fortaleza, 18.vii.1938, coll. Fonseca; mite deposited in the IBSP (reg. no. IBSP 1688).

ZooBank registration: To comply with the regulations set out in article 8.5 of the amended 2012 version of the International Code of Zoological Nomenclature (ICZN, 2012), details of the new species have been submitted to ZooBank. The Life Science Identifier (LSID) for Leptus (Leptus) haitlingeri n. sp. is urn:lsid:zoobank.org:act:BCA4682B-1993-4519-9C5E-BA2B99AC47D8.

Etymology: The name is given in honor of the Polish researcher Professor Ryszard Haitlinger, in recognition of his contributions to the knowledge of Brazilian Erythraeidae.


Description (Figs. 1–4)

Fig. 1
figure 1

Morphological details of Leptus (Leptus) haitlingeri n. sp. Holotype. A, Leg I; B, Leg II; C, Leg III; D, Palp tarsus, ventral view; E, Gnathosoma, ventral view; F, Gnathosoma, dorsal view; G, Prodorsal sclerite; H, Idiosoma, dorsal view; I, Idiosoma, ventral view. Black spots: ventral setae of the idiosoma; white spots: dorsal setae of the idiosoma. Abbreviations: ζ, eupathidium on palp tarsus and on tarsus of legs I-III; ω, solenidion on palp tarsus and on tarsus of legs I-II; Od, odontus; as, anterior hypostomalae setae; bs, posterior hypostomalae setae; cs, galeal setae; elcp, supracoxal setae; ve, anterolateral setae; se, posterolateral setae; vi, anterior trichobothria; si, posterior trichobothria; σ, solenidia on the genu of legs I-III; κ, microsetae on genu of legs I-II and tibia of leg I; φ, solenidia on the tibia of legs I-III; ε, famulus on the tarsus of legs I; 1a, anterior sternal setae; 2a, medium sternal setae; 3a, posterior sternal setae; 1b, seta of the coxal field of leg I; 2b, seta of the coxal field of leg II; 3b, seta of the coxal field of leg III. Scale-bars: A–G, 50 µm; H, I, 100 µm

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Larva [Based on the holotype and 7 paratypes; Tables 1, 2, 3, and 4.] Gnathosoma: palp setal formula B/B/BBB/4B2Nζω (Figs. 1D–F); odontus entire, chelicera with expanded base and long narrow neck terminating in cheliceral blade with tricuspid cap; gnathobase punctate (Fig. 3D); nude galeal setae (cs); nude adoral setae (as), branched subcapitular setae (bs), longer than adoral setae; with supracoxal setae (elcp) (Figs. 1E, F). Idiosoma: eyes 2, prodorsal sclerite punctate, pentagonal shape with 2 pairs of flagelliform trichobothria (si and vi), 1 pair of ve (= AL) setae and 1 pair of se (= PL); se ≥ ve > si > vi; distal quarter of si and vi with setules; anterior margin of prodorsal sclerite concave (Figs. 1G, 3A, B). Idiosoma with 68–76 setae, 50–58 scattered dorsal opisthosomal setae with small setules (Figs. 1H, 4A); ventral idiosoma with 16–18 setae with small setules on only one side (Figs. 1I, 4B), 1 pair of 1a setae (Fig. 4D), 1 pair of 2a setae (Fig. 4E) and 2 pairs of 3a setae (Figs. 4G, H), anterior pair of 3a setae (A3a) shorter than posterior pair (P3a) (Fig. 1I, K). Legs: femur legs I-III each divided into basifemur and telofemur, each leg terminated with pair of falciform claws with onychotriches, and pulvilliform empodium; solenidia and eupathidia on legs without companion setae (z); coxal fields punctate. Leg I: coxal field with 1 branched seta 1b (1B) (Fig. 4C) and a peg-like supracoxal seta; trochanter 1B; basifemur 2B; telofemur 5B; genu 8B, σ, with κ; tibia 14B, 2 φ, with κ; tarsus 27B, with ω, ε, terminating with subterminal eupathid (ζ), famulus (ε) distal to ω (Figs. 1A, 2A, 3C). Leg II: coxal field seta 2b (1B) (Fig. 4F); trochanter 1B; basifemur 2B; telofemur 5B; genu 8B, with κ; tibia 15B, 2 φ; tarsus 27B, with ω, with subterminal eupathids (ζ) near distal end of segment, (Figs. 1B, 2B). Leg III: coxal field seta 3b (1B) (Fig. 4I), trochanter 1B; basifemur 1B; telofemur 5B; genu 8B; tibia 15B, φ; tarsus 26B, and subterminal eupathid (ζ) (Figs. 1C, 2C).

Table 1 Standard measurements of Leptus (Leptus) haitlingeri n. sp.
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Table 2 Standard measurements of Leptus (Leptus) haitlingeri n. sp.
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Table 3 Standard measurements of Leptus (Leptus) haitlingeri n. sp.
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Table 4 Standard measurements of Leptus (Leptus) haitlingeri n. sp.
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Fig. 2
figure 2

Morphological details of Leptus (Leptus) haitlingeri n. sp. Holotype. A, Tarsus of leg I; B, Tarsus of leg II; C, Tarsus of leg III. Black spots: ventral setae of the idiosoma; white spots: dorsal setae of the idiosoma. Abbreviations: ζ, eupathidium on tarsus of legs I-III; ω, solenidion on tarsus of legs I-II; ε, famulus on the tarsus of leg I. Scale-bars: 50 µm

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Fig. 3
figure 3

Morphological details of Leptus (Leptus) haitlingeri n. sp. Paratype. A, Prodorsal esclerite, anterior view; B, Prodorsal esclerite, posterior view; C, Solenidion and famulus on tarsus of leg I; D, Details of the punctuation on the gnathobase. Abbreviations: ω, solenidion on tarsus of leg I; ve, anterolateral setae; se, posterolateral setae; vi, anterior trichobothria; si, posterior trichobothria; ε, famulus on the tarsus of leg I. Scale-bars: 20 µm

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Fig. 4
figure 4

Morphological details of the setae of Leptus (Leptus) haitlingeri n. sp. Paratype. A, Dorsal idiosomal seta; B, Ventral idiosomal seta; C, Seta of the coxal field of leg I; D, Seta between coxae I on ventral side of idiosoma; E, Seta in between coxae II on ventral side of idiosoma; F, Seta of the coxal field of leg II; G, Anterior setae in between coxae III on ventral side of idiosoma; H, Posterior setae in between coxae III on ventral side of idiosoma; I, Seta of the coxal field of leg III. Abbreviations: 1a, length of setae between coxae I on ventral side of idiosoma; 2a, length of setae in between coxae II on ventral side of idiosoma; A3a, length of anterior setae in between coxae III on ventral side of idiosoma; P3a, length of posterior setae in between coxae III on ventral side of idiosoma; 1b, length of the setae on coxa I; 2b, length of the setae on coxa II; 3b, length of the setae on coxa III. Scale-bars: 20 µm

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Post-larval instars unknown.


Differential diagnosis


Leptus (Leptus) haitlingeri n. sp. possesses four branched and two nude setae on palptarsus, two pairs of adoral setae (as and cs) and one pair of subcapitular setae (bs); the anterior pair (as) is shorter than the cs, the subcapitular setae (bs) are branched and longer. The new species is similar to the Neotropical species with a single seta on the palpfemur and the palpgenu, two pairs of 3a setae and one solenidion on genu of the leg I. These species include: L. (L.) adaminae; L. (L.) alberti; L. (L.) annikae Haitlinger, 2000; L. (L.) ariel; L. (L.) cyryli; L. (L.) fozicus; L. (L.) mariani; L. (L.) nikanori Haitlinger, 2000; L. (L.) olafi Haitlinger 1991; L. (L.) onnae; L. (L.) simonettae Haitlinger, 2000; L. (L.) stolae; and L. (L.) tiranicus Haitlinger, 2006 (see Haitlinger, 1987, 1991, 2000a, b, 2004, 2006; Southcott, 1989). However, the new species differs from L. (L.) adaminae in having bs branched (vs nude), palptarsus with 4B2Nζω (vs 2B4Nζω) and a palptibial formula BBB (vs NBB); from L. (L.) annikae in having a shorter as, bs branched (vs nude), and palptarsus with 4B2Nζω (vs 3B3Nζω); from L. (L.) ariel in having bs branched (vs nude) and a larger ω on the tarsus of leg I; from L. (L.) cyryli in having a shorter prodorsal sclerite (73–90 vs 100 µm), a concave anterior border (vs anterior border straight), a larger ωI (62–66 vs 52 µm), and a shorter φ′ II (10–12 vs 20 µm), φ″ II (30–33 vs 40 µm) and φ′ III (30–33 vs 42 µm); from L. (L.) fozicus in having palptarsus with 4B2Nζω (vs 2B4Nζω) and a palptibial formula BBB (vs NBB); from L. (L.) mariani in having palptarsus with 4B2Nζω (vs 6Nζω), a smaller prodorsal sclerite (length: 73–90 vs 98–102 µm; width: 106–119 vs 128–133 µm), AW (78–88 vs 92–94 µm), PW (94–108 vs 113–118 µm)] and a longer branched (vs nude) bs (41–54 vs 27–30 µm, cited incorrectly as as); from L. (L.) nikanori in having the palptarsus with 4B2Nζω (vs 1B5Nζω), unfortunately the original description did not describe the adoral or subcapitular setae; from L. (L.) olafi and L. (L.) alberti in having bs branched (vs nude), larger ω on the tarsus of leg I, palptarsus with 4B2Nζω (vs all setae nude); from L. (L.) onnae in having palptarsus with 4B2Nζω (vs 1B5Nζω), larger ω on the tarsus of leg I; from L. (L.) simonettae in having palptarsus with 4B2Nζω (vs 2B4Nζω), bs branched (vs nude); from L. (L.) stolae in having palptarsus with 4B2Nζω (vs 6Nζω); and from L. (L.) tiranicus in having palptarsus with 4B2Nζω (vs 1B5Nζω), bs branched (vs nude), incorrectly cited in original description as as.

Key to the larvae of Leptus spp. in Brazil

1a Palpgenu with two setae ……………………… L. (L.) iguacuicus Haitlinger, 2004

1b Palpgenu with one seta ……… 2

2a Leg III with a single solenidion on the tibia; no solenidia on the genu, telofemur and basifemur of leg III ……… 3

2b Leg III with numerous solenidia on the tibia, genu, telofemur and basifemur ……………………… L. (L.) candangus Šundić, Haitlinger & Pompermaier, 2017

3a Genu of leg I with one or no solenidion (σ) ……… 4

3b Genu of leg I with five σ ……………………… L. (L.) stieglmayri (Oudemans, 1905)

4a Genu of leg I with one solenidion (σ) ……… 5

4b Genu of leg I without solenidia ……………………… L. (L.) planaltensis Haitlinger, Šundić & Pompermaier, 2017

5a Genu of leg II without solenidia; palptarsus with at least one branched seta ……… 6

5b Genu of leg II with one solenidion; palptarsus without branched setae ……………………… L. (L.) mariani Haitlinger, 1991

6a Tibia of legs I-III each < 300 µm long ……… 7

6b Tibia of legs I-III each > 300 µm long ……………………… L. (L.) stolae Haitlinger, 1987

7a Tibia of leg III < 200 µm long; dorsal opisthosoma setae usually < 50 µm long ……… 8

7b Tibia of leg III > 200 µm long; dorsal opisthosoma setae usually > 60 µm long ……………………… L (L.) cyryli Haitlinger, 1991

8a Palptarsus with at least 2 branched setae ……… 10

8b Palptarsus with 1 branched seta (fPTa = 1B5Nζω) ……… 9

9a Dorsal opisthosoma with at least 60 setae; dorsal opisthosomal setae filiform ……………………… L. (L.) onnae Haitlinger, 2000

9b Dorsal opisthosoma with less than 50 setae; dorsal opisthosomal setae lanceolate ……………………… L. (L.) brasilicus Haitlinger, Šundić & Pompermaier, 2017

10a Palptarsus with no more than 2 branched setae ……… 11

10b Palptarsus with 4 branched setae (fPTa=4B2Nζω) ……………………… L. (L.) haitlingeri n. sp.

11a Tarsus of legs I and III each < 100 μm long; tibia of leg I each < 110 μm long; tibia of leg III each < 130 μm long ………………………… L. (L.) adaminae Haitlinger, 2004

11b Tarsus of legs I-III each > 120 μm long; tibia of legs I and III each > 130 μm long; tibia of leg III each > 150 μm long ……………………… L. (L.) fozicus Haitlinger, 2004


Leptus (L.) alberti Haitlinger, 1991 is omitted from the key due to an incomplete description.

Discussion

In the present study we are describing a new species, providing morphological images obtained in DIC observations. With this technique other characteristics can be observed, such as the ornamentation of the prodorsal sclerite, gnathobase and coxae field (in this case punctuated) and the shape of the dorsal and ventral setae of the idiosoma. These characteristics can be corroborating to identify the species, mainly species known only by the holotype, or when partially damaged.

Besides that, the problems with previously published keys to the species of Leptus of South America resulted from the low number of specimens examined and the high reliance on metrical data to separate species. Many species are known only from the holotype which makes species comparisons using metrical data of limited value. In this key we used mostly non-metric characters from published descriptions to differentiate Brazilian Leptus spp. It is our hope that future descriptions of South American species of Leptus will be complete and accurate.