Spinilimnesia insolitipes, Smit & Batista-Ribeiro, 2025

Spinilimnesia insolitipes n. sp.

https://zoobank.org/ urn:lsid:zoobank.org:act:

Figs 1-2 View Figure 1 View Figure 2

Material examined. Holotype male, Rio Cuiabá , Córrego Ajuricaba, in marshy forest, 15°49’16” S 55°13’3” W, Mato Grosso State, Brazil, November 22, 1994, leg. M. Wantzen ( Senckenberg Naturmuseum, Frankfurt am Main). GoogleMaps

Description. Male: Idiosoma colour reddish, dorsally 486 long and 405 wide, ventrally 519 long. Integument soft. Idiosoma anterodorsally with a pair of postocularia platelets, 104-108 long and 52-54 wide. Posterodorsally a relatively large platelet, 96 long and 130 wide ( Fig. 1A View Figure 1 ). Besides the aforementioned platelets, four more pairs of small dorsal platelets present. Gnathosoma 110 long ( Fig. 1E View Figure 1 ). Coxae in four groups, Cx-I separated medially, Cxgl-4 absent ( Fig. 1B View Figure 1 ). Genital field 124 long and 128 wide, with five pairs of acetabula of different size, ranging in shape from rounded to rectangular. Genital flaps bearing at outer margin 10-15 fine setae of moderate length, 4 in anterior and central part, the remaining posteriorly. Anterior to the genital flaps a small rounded pregenital sclerite. Vgl-1 and-3 between genital field and Cx-IV. Ejaculatory complex not well visible but very likely small. Posterior to the genital field a large plate with the excretory pore and Vgl-2 and Vgl-4, which extends onto the dorsum.. Length of P1-5: 18, 84, 46, 108, 34. P1 without setae; P2 with three dorsal setae and one distoventral seta (short and not thickened, not on a tubercle); P3 with three setae, two dorsally and one medially; P4 with a small dorsal hump in proximal part, one long ventral seta associated with a pointed tubercle; P5 with three large claws ( Fig. 1C View Figure 1 ). Shape and setation of legs as given in Figs 2 View Figure 2 A-D, all without swimming setae. Length of I-leg-1-6 ( Fig. 2A View Figure 2 ): 54, 56, 68, 88, 114, 110; length of II-leg-1-6: 52, 68, 82, 110, 136, 130; length of III-leg-2-6 ( Fig. 2B View Figure 2 , lost during mounting): 62, 85, 162, 154, 163. Length of IV-leg-1-6: 102, 76, 90, 90, 140, 96. IV-leg-1 enlarged, much larger than other segments of the leg; IV-leg-5 ventrally with four large, stout blunt setae arranged at regular distances, the distal one more slender and more curved ( Fig. 2 View Figure 2 C-D). IV-leg-6 short and slender, inserted sub-distally, with three setae, two fine ventrally, a slightly longer one sub-distally, the latter 34 long.

Female: Unknown.

Etymology. Named for the unusual fourth leg: insolitus (Latin) – unusual, strange, pes – foot (Latin).

Acknowledgements

We are indebted to Peter Jäger (SMF) for his permission to study the material, and to Jana Grüger (SMF) for sending the material to Leiden. Reinhard Gerecke (Tübingen) sorted the material of Schwoerbel and his colleagues lodged in SMF. Dante Batista-Ribeiro acknowledges the Fundação de Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) - Desk Sandwich Doctorate Program (PDSE) Edital Nº 06/2024 for their scholarship. We thank Reinhard Gerecke and an anonymous reviewer for their comment, which improved the paper substantially.

References

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Goldschmidt, T. ( 2004) Studies on Neotropical Limnesiidae Thor, 1900. Part II: Tyrrellinae Koenike, 1910 (Acari, Actinedida, Hydrachnidia). Archiv für Hydrobiologie, Supplement, 151 (1- 2), 25– 68.

Rosso de Ferradás, B. & Fernández, H.R. ( 2005) Elenco biogeografía de los Ácaros acuáticos (Acari, Parasitengona, Hydrachnidia) de Sudamérica. Graellsia, 61 ( 2), 181–224.

Smit, H. ( 2020) Water mites of the world with keys to the families, subfamilies, genera and subgenera (Acari: Hydrachnidia). Monografieën van de Nederlandse Entomologische Vereniging, 12, 1– 774.