# The genus Sperchon Kramer 1877 in Brazil, with the description of a new species, new records and a key to the Neotropical species of the genus (Acari: Hydrachnidia: Sperchontidae)

Dante Batista-Ribeiro, Harry Smit

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## To cite this version:

Dante Batista-Ribeiro, Harry Smit. The genus Sperchon Kramer 1877 in Brazil, with the description of a new species, new records and a key to the Neotropical species of the genus (Acari: Hydrachnidia: Sperchontidae). Acarologia, 2025, 65 (2), pp.373-379. 10.24349/4ovf-gy3a. hal-05059137

HAL Id: hal-05059137

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Submitted on 7 May 2025

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# The genus *Sperchon* Kramer 1877 in Brazil, with the description of a new species, new records and a key to the Neotropical species of the genus (Acari: Hydrachnidia: Sperchontidae)

Dante Batista-Ribeiro ID a,b, Harry Smit ID a,c

## Original research

### ABSTRACT

A new species of the genus *Sperchon*, *S. pinnatus* sp. nov., is described from Mato Grosso do Sul state, Brazil. Moreover, new records are reported of *S. neotropicus* Cook, 1980 from Brazil. Finally, a key is provided for the Neotropical *Sperchon* species based on the adults. We assigned *S. oaxacensis* Otero-Colina, to *Sperchon* s.s. subgenus based on the presence of papillae on its integument.

**Keywords** water mites; new taxa; new records; pinnate setae; South America

**Zoobank** http://zoobank.org/B8665137-9BE6-4C18-AB5B-5F0C7009CEFD

### 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.

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<footnote>a Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, the Netherlands.</footnote>

<footnote>b 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.</footnote>

<footnote>c Museums Victoria Research Institute, Museums Victoria, GPO Box 666, Melbourne, VIC 3001, Australia.</footnote>
**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 – Coxeae 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).
<figure><img src="image_4.png" /><figcaption>**Figure 1** *Sperchon pinnatus* sp. nov., ♀ holotype: A – idiosoma, dorsal view; B – idiosoma, ventral view; C – genital field; D – gnathosoma; E – palp. Scale bars = 100 µm</figcaption></figure>

**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.
<figure><img src="image_5.png" /><figcaption>**Figure 2** *Sperchon pinnatus* sp. nov., ♀ holotype: A – I-Leg-2-6; B – II-Leg-3-6; C – III-Leg-1-6; D – IV-Leg-4-6. Scale bars = 100 µm</figcaption></figure>

**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*.
<figure><img src="image_6.png" /><figcaption>**Figure 3** *Sperchon pinnatus* sp. nov., ♂ paratype: A – idiosoma, dorsal view; B – idiosoma, ventral view; C – genital field; D – palp. Scale bars = 100 µm</figcaption></figure>

**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.
ORCID

Dante Batista-Ribeiro https://orcid.org/0000-0002-7503-0488

Harry Smit https://orcid.org/0000-0002-0376-6808

References

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