1✉ Laboratório de Acarologia, Tecnovates, Universidade do Vale do Taquari - Univates, 95914-014, Lajeado, Rio Grande do Sul, Brazil.
2Embrapa Amazônia Oriental, Tv. Dr. Enéas Pinheiro, s/n, 66095-903, Belém, Pará, Brazil.
3Laboratório de Acarologia, Tecnovates, Universidade do Vale do Taquari - Univates, 95914-014, Lajeado, Rio Grande do Sul, Brazil.
4Laboratório de Acarologia, Tecnovates, Universidade do Vale do Taquari - Univates, 95914-014, Lajeado, Rio Grande do Sul, Brazil & CNPq Researcher.
5Laboratório de Acarologia, Tecnovates, Universidade do Vale do Taquari - Univates, 95914-014, Lajeado, Rio Grande do Sul, Brazil.
2020 - Volume: 60 Issue: 4 pages: 825-830https://doi.org/10.24349/acarologia/20204403
The predaceous stigmaeid mites (Acari: Stigmaeidae) are cosmopolitan, worldwide distributed and with a huge morphologic diversity (Krantz and Walter, 2009). Stigmaeidae is the largest group belonging to the superfamily Raphignathoidea and includes 608 species of 33 valid genera, among them, the genus Eustigmaeus Berlese comprises of 131 species to date (Fan et al. 2016; 2019; Akyol, 2019).
The genus Eustigmaeus is the second-largest within Stigmaeidae, characterized by a dorsoventrally globate body with dorsal shields strongly ornamented with dimples. They are found in soil, mosses and litter habitats (Krantz & Walter, 2009). Four species of Eustigmaeus genus are described for Brazil: E. bryonemus Flechtmann, 1985 from moss, E. microsegnis (Chaudhri, 1965) from leaf debris, mosses, soil, Pinus spp. and rocks, E. oliveirai Paktinat-Saeij & Bagheri, 2016 from humus on unidentified tree and E. piracicabensis Paktinat-Saeij & Bagheri, 2016 from soil and humus under rubber trees (Hevea brasiliensis L., Euphorbiaceae) Fan et al. (2016; 2019). This paper describes Eustigmaeus crassifolius n. sp. found on Byrsonima crassifolia (L.) Kunth. (Malpighiaceae) and a dichotomous key of Brazilian species of Eustigmaeus is provided.
Leaf collections were carried out in crop clones of Byrsonima crassifolia located in experimental area of Embrapa Amazônia Oriental, where no chemical management was applied. The sampled area was located in the municipality of Belém (1°26'09.2'' S 48°26'28.6'' W), Pará state, Brazil. A total of 200 leaves were collected per month between V/23/2012 and XI/03/2014 and kept in plastic bags in a refrigerated box for transportation.
The abaxial and adaxial surfaces of the leaves were examined and mites were collected under a stereomicroscope (Leica S6E), mounted in Hoyer's medium and identified under phases contrast microscope (Zeiss Imager.Z2) based on Fan et al. (2016) and Paktinat-Saeij et al. (2016). The species was illustrated using a lucid camera and processed in Corel-DRAW X8®. All measurements are shown in micrometers and were taken with Zeiss Zen Imaging Software. For each structure, measurement of the holotype is presented, followed by the ranges for the paratypes (in brackets). Body length measurements represent the distance between base of gnathosoma and posterior end of idiosoma; width was measured at the broadest level; gnathosoma including palp. Setae were measured from the insertion base to the tip of the seta; distances between setae were measured between setal insertions. Leg measurements are from the coxa base to tip of tarsal claw. The terminology and nomenclature follows Kethley (1990).
Type species Eustigmaeus kermesinus (Koch, 1841)
Description Female (n = 6) — Dorsum of idiosoma – (Fig. 1A). Length of idiosoma 257 (245–262); width 213 (202–222); it is covered by two large shields, leaving exposed margin of unsclerotized cuticle around edges; shield ornamentation consists of asymmetrical oval dimples composed by small circles of equal sizes, dimples bearing vacuoles (Fig. 1B and Fig. 3). Prodorsal shield triangular and bearing four pairs of feather-like setae (vi, ve (Fig. 1D), sci and sce) and one pair of eyes between setae ve and sci. Humeral shields with bigger, irregular dimples and c2 inserted on it; hysterosomal shield with six pairs of feather-like setae (c1, d1, d2, e1, e2 and f1 (Fig. 1E)); dorsal body setae inserted on tubercles. Length of dorsal setae: vi 50 (47–53); ve 56 (50–60); sci 46 (44–50); sce 54 (52–59); c1 55 (49–55); c2 50 (47–52); d1 57 (55–57); d2 56 (52–57); e1 53 (49–60); e2 57 (52–60); f1 53 (50–55); h1 31 (29–35); h2 23 (23–24). Distances between dorsal setae: vi–vi 18 (14–19); ve–ve 62 (61–65); vi– ve 28 (23–31); ve–sci 28 (28–29); sci–sci 110 (108–113); sce–sce 144 (142–148); sci–sce 33 (32–36); c1–c1 70 (63–76); c1–d1 38 (36–40); c1–c2 66 (62–75); c1–d2 54 (53–58); c2–c2 189 (185–247); d1–d1 60 (57–67); d1–d2 52 (48–53); d1–e1 61 (61–67); d1–e2 62 (58–64); d2–d2 162 (154–162); d2–e2 59 (58–60); e1–e1 55 (52–56); e1– e2 40 (39–44); e2–e2 130 (122–131); e1–f1 43 (40–47); f1–f1 48 (44–51); h1–h1 21 (20–21); h2–h2 62 (58–66); h1–h2 20 (19-21).
Venter of idiosoma – (Fig. 1C). Endopodal plates, smooth, fused, separated by transverse striae between coxae II and III, bearing three pairs of setae (1a, 3a and 4a).
Anogenital area with unsclerotized smooth shield fused to the suranal shield; genital area with one pair of aggenital (ag1) and three pairs of pseudanal (ps1–ps3) setae, all slightly serrate to smooth; genital opening surrounded with striae. Suranal area unsclerotized, bearing irregular oval dimples equal to humeral shield situated dorsoventrally and bearing h1 and h2 setae. Measurements of setae: 1a 13 (12–14); 3a 11 (11–12); 4a 12 (11–16); ag1 12 (11–14); ps1 13 (13–15); ps2 12 (11–12); ps3 11 (10–12).
Gnathosoma – Length 77 (66–84); subcapitulum bearing smooth subcapitular setae m 9 (8–10) and n 8 (8–9) and adoral setae or1 8 (7-8) and or2 7 (7-8). Palp 66 (62–74) long (Fig. 2E) five segmented; with thick smooth and serrate setae; palptrochanter without setae; palpfemur with three setae (d, v and l); palpgenu with two setae (l and d); palptibia with two setae (l and d) + one well-developed claw; palptarsus with five tactile setae (l', l'', v, lp and va) + one solenidion (ω) and one distal trifurcate eupathidium (ulξ+sulξ).
Legs – (Fig. 2A-D) Length of legs I–IV: 176 (165–176); 161 (142–161); 125 (119–135); 174 (151–174); with smooth to slightly serrate and thick leaf-like setae. Leg chaetotaxy as follows: coxae (excluding 1a, 3a and 4a) 3-2-2-2, trochanters 2-1-2-1, femora 5-5-2-2, genua 3(1κ)-3-1-1, tibiae 5(1φ)-4-4-4, tarsi 12(1ω)-7(1ω)-6(1ω)-6. Length of solenidion: ωI 19 (18–22), φ 10 (9-11); ωII 18 (20–23); ωIII 13 (12–14).
Immature stages and male — Unknown.
Remarks — The new species resembles Eustigmaeus floridensis Maake, Ueckermann & Childers 2016 by having recurved, acute and feather-like dorsal setae, dorsal ornamentation with oval dimples, same number of aggenital and pseudoanal setae and suranal shield smooth with rounded ornamentation bearing h1 and h2. The new species differs from E. floridensis by having less setae in tarsi I 13(1) in E. floridensis vs 12(1) in E. crassifolius n. sp.; larger outlined dimples associated with sce, d2 and e1 setae present in E. floridensis but absent in E. crassifolius n. sp.; pseudoanal and aggenital setae thick and strongly serrated in E. floridensis but slightly serrated to smooth in E. crassifolius n. sp.; palptibia in E. floridensis with small spine-like claw and one developed claw vs small spine-like claw on palptibia absent in E. crassifolius n. sp.; dimples in E. floridensis without vacuoles vs vacuoles sieve-like, evenly spread inside the dimples in E. crassifolius n. sp. The new species also resembles E. segnis (Koch, 1836) and E. microsegnis but can be easily distinguished by having reticulated endopodal shield and tarsi II with 8(+1) in E. segnis; tarsi II with 9(+1) in E. microsegnis vs smooth endopodal shield and tarsi II with 7(+1) in E. crassifolius n. sp..
Etymology — The species name refers to the host plant Byrsonima crassifolia.
Type material — One holotype collected in July 18, 2013. Two paratypes collected in June 04, 2013 ; One paratype collected in March 25, 2014; Two paratypes collected in September 23, 2014 on Byrsonima crassifolia in Belém city (1°26'09.2'' S 48°26'28.6'' W), Pará state, Brazil. Holotype female deposited at Departamento de Entomologia e Acarologia, Escola Superior de Agricultura ''Luiz de Queiroz'', Universidade de São Paulo (ESALQ/USP), Piracicaba, São Paulo State, Brazil. All paratypes are deposited at Museu de Ciências Naturais (ZAUMCN), Universidade do Vale do Taquari - Univates, Lajeado, Rio Grande do Sul, Brazil.
Adapted from (Paktinat-Saeij et al., 2016)
1. Dorsal setae feather-like, slightly to strongly serrated or smooth
— Dorsal setae smooth, clavate or cub-like
2. Distance between c1-c1 more than 55 μm.
— Distance between c1-c1 less than 50 μm
...... E. microsegnis (Chaudhri)
3. Tarsus II with 9(+1) setae; endopodal shield reticulated...
...... E. oliverai Paktinat-Saeij & Bagheri
— Tarsus II with 7(+1) setae; endopodal shield with no reticulation.
...... E. crassifolius n. sp.
4. With three pairs of aggenital setae and dorsal shield reticulated with polygonal depressions
...... E. piracicabensis Paktinat-Saeij & Bagheri
— With two pairs of aggenital setae and dorsal shield ornamented with minute dimples
...... E. bryonemus Flechtmann
The authors are grateful to Universidade do Vale do Taquari - Univates for providing all necessary materials during the study and to FAPERGS - Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul for the scholarship granted to the first author. To Empresa Brasileira de Pesquisa Agropecuária (Embrapa Amazônia Oriental – project 02.11.02.001.00.00). This study was funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Funding Code 001. PhD. Noeli Juarez Ferla was supported by a productivity scholarship (Process number 310035/2017-1).
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