Batista-Ribeiro, Dante ¹ and Smit, Harry ²

¹✉ Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, the Netherlands & Programa de pós-graduação em Zoologia, Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Departamento de Zoologia, Laboratório de Sistemática e Evolução de Ácaros Acariformes, Av. Antonio Carlos, 6627, Pampulha, Belo Horizonte - MG, Brazil.
²Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, the Netherlands & Museums Victoria Research Institute, Museums Victoria, GPO Box 666, Melbourne, VIC 3001, Australia.

2025 - Volume: 65 Issue: 2 pages: 373-379

ZooBank LSID: B8665137-9BE6-4C18-AB5B-5F0C7009CEFD

Original research

Keywords

Abstract

Introduction

The genus Sperchon Kramer, 1877 is relatively rare in South America: up to now, only five species have been described: S. brasiliensis Lundblad, 1939, S. andinus Lundblad, 1953, S. motasi Lundblad, 1954, S. gledhilli K.O. Viets, 1977, S. neotropicus Cook, 1980 and S. quintus Smit & Pešić, 2024 (Rosso de Ferradás and Fernández 2005; Smit and Pešić 2024). The genus is more common in the Northern Hemisphere, from Europe 19 species are known (Di Sabatino et al. 2010), and from North America 21 (Habeeb 1967, 1974; see also Conroy 1991), but we consider that the genus is in need of revision: there are North American species whose descriptions are lacking important information about the venter, palps and/or legs (e.g. S. avimontis Habeeb, 1957; S. neomexicanus Habeeb, 1963; S. mugyonensins Habeeb, 1963), as well as some European species which are currently classified as species incerta (e.g. S. ornatus Halbert, 1944; S. hystrix Komárek, 1921) (Habeeb 1963a, 1963b; Di Sabatino et al. 2009). Moreover, recent molecular studies have shown that some Sperchon species, such as S. clupeifer Piersig, 1896, and S. algeriensis Lundblad, 1942, exhibit high genetic divergence across its populations, suggesting that the different populations may represent distinct species (Pešić et al. 2024), while other species, such as S. amuzgari Bader & Sepasgosarian, 1979, was resurrected as a distinct species from S. hispidus Koenike, 1895 (Pešić et al. 2021).Here, we describe the sixth Sperchon species from South America, S. pinnatus sp. nov. New records are given of S. neotropicus. Finally, we provide a key for the Neotropical species of the genus.

Material and methods

The majority of the material was collected by a team of the Laboratório de Ecologia de Bentos (Universidade Federal de Minas Gerais) via kick sampling, with a D-frame sampler and a 500 μm mesh size. Sperchon neotropicus from Rio de Janeiro state was collected by a team of Laboratório de Acarologia (Universidade Federal de Minas Gerais) following the same method. The following abbreviations have been used: Cx-I-IV – Coxae I-IV; Cxgl-1-4 – coxoglandularia 1-4; I-IV-leg-1-6 – first to sixth segments of first to fourth leg; L – Length; LEB – Laboratório de Ecologia de Bentos; P–1-5 – first to fifth palp segment; W – Width.

The holotype will be lodged in the Centro de Coleções Taxonômicas da UFMG, Belo Horizonte (CCT-UFMG), paratypes both in CCT-UFMG and Naturalis Biodiversity Center, Leiden (RMNH).

Measurements of leg segments and palp are of the dorsal margin, the venter is measured from the tip of Cx-I till the posterior idiosoma margin.

The specimens described and reported here were fixed in ethanol. Before mounting, they were cleared with Proteinase K and ATL-buffer fluid, then lactic acid 85% for two days, after which the material was preserved in Koenike fluid.

The measurements of P-4 on S. mexicanus Cook, 1980 were based on its drawings.

Taxonomy

Family Sperchontidae Thor

Genus Sperchon Kramer, 1877

Sperchon pinnatus sp. nov.

ZOOBANK: BC3F5F39-66B4-448B-88D6-9F258779FF1C

Material examined

Holotype — ♀, 22°31′59″ S 53°03′56″ W, Paraná River, São Silvério, Batayporã, Mato Grosso do Sul state, Brazil, 2011.

Paratypes — 3♂ 3♀ 1 nymph, same data as holotype; 1♂ 1♀ Lagoa Azul, Osvaldo Cruz, São Paulo State 21°36′35.991″ S 50°48′20.454″ W, 4 Sept. 2010; 1♂, Monções, 20°50′59.98″S 50°04′56.94″ W, 2010.

Diagnosis

Coxae small, Cx-III without glandularia, integument papillate, genital field not reaching posterior end of Cx-IV, setae of genital flaps short, distoventral projection of P2 short, legs with pinnate setae.

Description

Females — Integument dorsally and ventrally papillate, glandularia small, lying on the integument (Fig. 1A); Ventral view: Cx-I+II medially distant to each other, Cx-III without glandularia, Cxgl-4 lying medio-posteriorly to Cx-IV (Fig. 1B). Genital field lying anteriorly, not reaching beyond Cx-IV. Ac-1 longish, Ac-2-3 roundish. Setae on genital flaps short (Fig. 1C). Excretory pore surrounded by a sclerotized ring.

Gnathosoma slightly slender, rostrum shorter than gnathosomal base (Fig. 1D). P-1 without setae; P-2 with a short distoventral projection, at its tip bearing two fine setae; P-3 without ventral setae; P-4 longer than P-3, P-4 with a medial slightly developed ventral tubercle, bearing a medial peg-like seta and a distal peg-like, with a slightly enlarged dorsodistal seta (Fig. 1E).

Leg segments slender, I-V-L-1-5 with pinnate dorsal setae, claws slender, bearing clawlets. (Figs. 2A-D).

Males — Dorsal idiosoma similar to female (Fig. 3A); Venter similar to female, but Cxgl-4 are lying more distally (Fig. 3B). Genital field longer (L= 240 compared to L= 186 on females) and lying more medially, almost reaching beyond Cx-IV (Fig. 3B-C).

Gnathosoma similar to female. Palp shorter, P-3 more slender (L/H = 2.8, compared to 2.1 on females) and lacking medial setae, and P-4 comparatively stouter (L/H = 4.1, compared to 6 on females) (Fig. 3D).

Legs similar to female.

Measurements

Female (holotype) — Idiosoma L 1105, W 844; distance between anterior end of Cx-I and posterior end of Cx-IV, 656; Cx-III W 192; genital field L 186; pregenital sclerite W 100; Ac-1-3: 70, 56, 66; P-1 dL/H 22/100; P-2 dL/H 171/116; P-3 dL/H 182/87; P-4 dL/H 212/35; P-5 dL/H 40/32. Gnathosoma L 256. Chelicera L 228. I-L-1-6: 80, 164, 198, 226, 210, 202. II-L-1-6: 100, 110, 180, 290, 296, 214. III-L-1-6: 110, 104, 170, 250, 260, 200; IV-L-1-6: 120, 140, 180, 320, 330, 240.

Male (paratype) — Idiosoma L768, W 664; distance between anterior end of Cx-I and posterior end of Cx-IV, 496; Cx-III W 208; Genital field L 240; pregenital sclerite W 32; Ac-1-3: 88, 56, 72; P-1 dL/H 32/68; P-2 dL/H 122/82; P-3 dL/H 98/35; P-4 dL/H 142/34; P-5 dL/H 30/22. Gnathosoma L 230. Chelicera L 220. I-L-1-6:90, 110, 150, 240, 220, 170. II-L-1-6: 100, 120, 170, 240, 200, 180. III-L-1-6: 80, 120, 180, 260, 240, 230; IV-L-1-6: 160, 150, 200, 360, 320, 240.

Etymology

Named for the pinnate setae of the legs.

Discussion

The shape of the palp, specially regarding the short distoventral projection on P-2, resembles S. brasiliensis, but the new species has a papillate integument, and lacks the ventral setae of P-3. The short distoventral projection of P-2 and the pinnate setae of the legs separates the new species from the other South American Sperchon s. s. species, S. quintus and S. oaxacensis.

Sperchon neotropicus Cook, 1980

New records

Rio De Janeiro State. 0/1/0, Campo Belo River, Itatiaia National Park, 44°40′36" W, 22°23′08" S, 2350m, 22. Nov. 2022. Paraná State. 4/4/0, 23°04′42.92″ S 53°08′12.94″ W, 14. Sept. 2011; São Paulo State. 0/1/0, Monções, 20°50′59.98″ S 50°04′56.94″ W, 2010. Mato Grosso do Sul State. 0/1/0 Paraná river, Porto XV de Novembro, 21°41′38.761″ S 52°07′38.207″ W, Sept. 2013; 1/2/0 Vila Formosa, Anaurilândia 21°54′0.01″ S 52°36′07.751″ W, 2013.

Distribution

Previously reported from Veracruz and Coahuila states, Mexico, and on Buenos Aires province, Argentina (Cook 1980); Catamarca and Tucumán provinces in Argentina and Vallegrande, Bolivia (Fernandez and Achem 2024). These are the first records of this species in Brazil.

Key to the Neotropical Sperchon species based on adults

1. A pigmentless median eye present
...... S. pontifex Otero-Colina, 1987

— Median eye absent
...... 2

2. Integument papillated (Sperchon s.s.)
...... 3

— Integument reticulated (Hispidosperchon)
...... 5

3. Pinnate setae on legs, distoventral projection of P-2 short
...... . Sperchon pinnatus sp. nov.

— Simple setae on legs, distoventral projection of P-2 relatively long
...... 4

4. Papillae short, medial setae of P-2 absent
...... S. quintus Smit & Pešić, 2024

— Papillae very pronounced, P-2 with medial setae
...... S. oaxacensis Otero-Colina 1987

5. Ventral peg-like setae of P-3 absent
...... 6

— Ventral peg-like seta of P-3 present
...... 7

6. Thickened seta of P-3 lying medio-dorsally; distoventral projection of P-2 relatively long, glands present on the third coxae
...... S. gledhilli K.O. Viets, 1977

— Peg-like setae of P-3 lying medially; distoventral projection of P2 short; glands absent on the third coxae
...... S. brasiliensis

7. Ventral seta of P-3 lying on posterior end of segment
...... S. motasi Lundblad, 1954

— Ventral seta of P-3 lying medially or posteriorly, but not on the end of the segment
...... 8

8. Claws simple
...... S. andinus Lundblad, 1953

— Claws with clawlets
...... 9

9. Thickened ventral seta of P-3 lying medially, most anterior ventral seta of P-4 located medioanteriorly, P-2 and P-4 slender (P-2 L/H = 2; P-4 L/H = 9.5)
...... S. mexicanus Cook, 1980

— Thickened ventral seta of P-3 lying medio posteriorlly most anterior ventral seta of P-4 located medially, P-2 and P-4 stout (P-2 L/H = 1.4; P-4 L/H = 4.7)
...... S. neotropicus Cook, 1980

Acknowledgements

We are indebted to the team of LEB, specially Dr. Marcos Callisto, Dr. Kele Firmiano and Dr. Marden Linares, for the donation and providing the data of most of the material used in this work. We also thank Dr. Vladimir Pešić for kindly providing references for this paper. Dante Batista-Ribeiro acknowledges the Fundação de Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) - Desk Sandwich Doctorate Program (PDSE) Edital N° 06/2024 for their scholarship. We thank both anonymous reviewers for their comments, which improved the paper.

References

1. Conroy J.C. 1991. New species in the genus Sperchonopsis in North America with a description of a new subghenus, Sperchonopsella. Acarologia, 32: 29-39.
2. Cook D.R. 1980. Studies on Neotropical Water Mites. Mem.Am. Entomol. Inst. , 31: 1-645.
3. Di Sabatino A., Gerecke R., Gledhill T., Smit H. 2009. On the taxonomy of water mites (Acari: Hydrachnidia) described from the Palaearctic, part 2: Hydryphantoidea and Lebertioidea. Zootaxa, 2266: 1-34. https://doi.org/10.11646/zootaxa.2266.1.1
4. Fernández H.R., González Achem A.L. 2024. New Records of Watermites (Hydrachnidia) Collected from Macrophyte and Cladophora sp. in South America. Acta Biol. Colomb., 29(2), 109-116. https://doi.org/10.15446/abc.v29n2.105496
5. Habeeb H. 1957. North American Hydrachnellae. XLII-XLVII. Leafl. Acadian Biol., 16: 1-8.
6. Habeeb H. 1963a. Some comments by an amateur acarologist. Leafl. Acadian Biol., 29: 1-4.
7. Habeeb H. 1963b. Two novel mites from Rain Creek in the Mogollon Mountains of New Mexico. Leafl. Acadian Biol., 30: 1-2.
8. Habeeb H. 1967. A check list of North American Water-Mites. Leafl. Acadian Biol., 43: 1-8.
9. Habeeb H. 1974. Notes on Water-Mites. VIII. Leafl. Acadian Biol., 59: 1-4.
10. Pešić V., Zawal A., Ferreira S., Benitez-Bosco L., Cruz-Oliveira A., Girão D., Padilha A., Turaccio P., Rossini S., Ballini L., Staffoni G., Fratini S., Ciofi C., Iannucci A., Ekrem T., Stur E. 2024. DNA barcode library of Portuguese water mites, with the descriptions of two new species (Acari, Hydrachnidia). ZooKeys, 1217: 119-171. https://doi.org/10.3897/zookeys.1217.131730
11. Pešić V., Zawal A., Saboori A., Smit H. 2021. New records of water mites (Acari, Hydrachnidia) from Iran with the description of one new species based on morphology and DNA barcodes. Zootaxa, 5082(5): 425-440. https://doi.org/10.11646/zootaxa.5082.5.2
12. Rosso de Ferradás B., Fernández H.R. 2005. Elenco biogeografía de los Ácaros acuáticos (Acari, Parasitengona, Hydrachnidia) de Sudamérica. Graellsia, 61(2): 181-224. https://doi.org/10.3989/graellsia.2005.v61.i2.19
13. Smit H., Pešić V. 2024. A new Sperchon species from the high Andes of northern Chile (Acari: Hydrachnidia: Sperchontidae). Ecol. Monten., 74: 39-42. https://doi.org/10.37828/em.2024.74.5

instructions