New troglobitic species of Xangoniscus (Isopoda: Styloniscidae) from Brazil, with notes on their habitats and threats Cardoso, Giovanna Monticelli Bastos-Pereira, Rafaela Souza, Leila Aparecida Ferreira, Rodrigo Lopes Zootaxa 2020 2020-07-22 4819 1 84 108 84F4P Cardoso & Bastos-Pereira & Souza & Ferreira, 2020 Cardoso & Bastos-Pereira & Souza & Ferreira 2020 [151,390,1615,1642] Malacostraca Styloniscidae Xangoniscus GBIF,CoL Animalia Isopoda 5 89 Arthropoda species dagua sp. nov.   Figs. 5–8, 19B   Material examined.   Holotype: Male( ISLA77513), MG, Montes Claros, Parque Estadual da Lapa Grande, Lapa D’Água cave, 16.707038ºS, 43.920924ºW,  31 March 2015, leg. R. L. Ferreira.   Paratypes: 1 male, 1 female, same data as holotype ( ISLA14337);  3 males, same location as holotype,  20 December 2019( ISLA77522).   Etymology.The specific epithet means ‘from water’ in Portuguese. This refers to the name of the cave (Lapa D’Água cave) which represents the only known habitat of this species until the present.   Diagnosis.Antennula with four aesthetascs; antennal flagellum with five articles; pereopods 3 and 4 proximal margin of propodus concave, pereopods 5 and 6 with enlarged merus, pereopods 4–7 dactylus with setose sternal margin; male pleopod 1 exopod trapezoidal; male pleopod 2 exopod subtriangular; uropod exopod and endopod subequal in length.   Description.Maximum length: male, 9 mm. Colorless, eyesabsent ( Figs. 5A, 19B). Dorsal surface smooth ( Fig. 5A). Cephalon( Fig. 5B) with small antennary lobes; profrons with V-shaped suprantennal line, vertex with two transversal grooves. Posterior corners of pereonitesprogressively directed backwards, pereonite 7 not surpassing distal margin of pleonite 2; pleonites 3–5epimera posterior point not developed; pleon narrower than pereon ( Fig. 5A). Telson( Fig. 5C) with concave sides, round apex.   FIGURE 5.  Xangoniscus dagua  n. sp., male paratype.A, habitus, dorsal view; B, cephalon, frontal view; C, telson, dorsal view; D, antennula; E, antenna; F, left mandible; G, right mandible; H, maxillula; I, maxilla; J, maxilliped. Scale bars: A: 1 mm; B–J: 0.2 mm.  Antennula( Fig. 5D) with three articles, second article shortest, distal article with four short aesthetascs, one subapical and three apical. Antenna( Fig. 5E) reaches distal margin of pereonite 2 when extended backwards; fifth article of peduncle shorter than flagellum, with one long seta reaching haft length of first article of flagellum; flagellum with five articles. Left mandiblewith two penicils ( Fig. 1F), right mandiblewith one penicil, lacinia mobilisleaf-shaped ( Fig. 1G). Maxillula( Fig. 1H) outer branch with 5 + 5 teeth, apically entire, and two thick plumose stalks; inner branch with three penicils. Maxilla( Fig.1I) with bilobate apex, inner lobe wider than outer lobe with several setae on distal margin. Maxilliped( Fig. 1J) basis enlarged on distal portion; palp apex with four tufts of setae; endite rectangular, outer and medial margins setose, apex with one triangular penicil between two teeth.  Pereopod 1antennal grooming brush composed by serrated scale setae longitudinally on propodus and on sternal margin of carpus. Uropod( Fig. 6A) protopod longer than distal margin of telson; endopod and exopod sub equal in length, exopod with proximal insertion.  Male. Pereopods 1–6( Fig. 6B–E) merus with fringed scales on sternal margin; pereopods 3 and 4 propodus proximal margin concave, distal margin with fringed scales; pereopods 4–7 dactylus sternal margin setose; pereopods 5 and 6 merus enlarged, distal margin almost two times wider than proximal margin, wider than long. Pereopod 7 ( Fig. 6E) basis with scales of water conduction system. Genital papilla( Fig. 7A) lanceolate. Pleopod 1( Fig. 7B) exopod trapezoidal, distal margin straight; endopod longer than exopod, with narrow basal article and flagelliform distal article; protopod distal margin shorter than exopod. Pleopod 2( Fig. 7C) exopod triangular, round distal margin, bearing one seta; endopod of two articles, basal article rectangular, as long as exopod, distal article wrench-like, transverse pointed process on apex, directed outwards, with lateral membrane. Pleopod 3exopod ( Fig. 7D) ovoid, straight distal margin bearing setae. Pleopod 4exopod ( Fig. 7E) rhomboidal wider than long, with distal margin rounded and bearing setae. Pleopod 5exopod ( Fig. 7F) ovoid.   Remarks.  Xangoniscus dagua  n. sp.resembles  X. lundi  n. sp.by the modifications on pereopods, such as the proximal margin of propodus concave on pereopods 3 and 4, the enlarged merus in pereopods 5 and 6 and the setose sternal margin of dactylus on pereopods 4–7. However, these species can be distinguished by the number of aesthetascs on antennula (four versus three in  X. lundi  n. sp.), and the shape of male pleopod 1 exopod (trapezoidal versus triangular in  X. lundi  n. sp.).  Xangoniscus dagua  n. sp.also resembles  X. itacarambiensisby the shape of male pleopod 1 exopod and the length of uropod rami (exopod and endopod subequal in length), but differs in the margin of pereopod 4 dactylus (only setose in  X. dagua  n. sp.), the shape of pereopod 5 merus and pereopod 6 propodus (margin depressed only in  X. itacarambiensis).  Habitat and threats.Lapa D’Água cave is the only known habitat of  X. dagua  n. sp.until the present. This cave presents 1,234 mof horizontal projection and two distinct levels. The upper level (associated with the main entrance of the cave) comprises a predominantly linear conduit with heterogeneous floor substrates, varying from silt to collapsed rocks and dripstone floors ( Fig. 8A). At the innermost part of the upper level (approximately 400 mfar from the entrance), there is a set of speleothems characterized by massive dripstones with several travertine pools ( Fig. 8C, D). Specimens of  X. dagua  n. sp.were only found in this area, always associated with the travertine pools ( Fig. 8B). Despite the fact that there are some pools filled with water during the whole year, the population densities are higher during the rainy season and quite lower during the dry periods. This suggests the existence of vertical migrations between the macro cave and upper epikarstic habitats, as already observed for other species of this genus ( Silva et al. 2018). The lower level is trespassed by a drainage that enters the cave through a lower entrance located at the bottom of a sinkhole at the final portion of the cave. No specimens have ever been registered in this drainage probably due to the presence of (non-troglobitic) catfishes that may prey upon them. The cave is located within the limits of Parque Estadual da Lapa Grande; hence it is currently inserted in a protected area. However, the cave receives human visitors, most of them unaware of the presence of the isopods. Therefore, there may be eventual risks of stepping, so that a management plan for the cave touristic use is highly recommendable. 2015-03-31 MG, R L. Ferreira Iceland Lapa D'Agua cave -16.707039 Male 1 -43.920925 Parque Estadual da Lapa Grande 5 89 1 holotype 2015-03-31 MG, R L. Ferreira Iceland Lapa D'Agua cave -16.707039 Male 1 -43.920925 Parque Estadual da Lapa Grande 5 89 2 1 1 paratype [506,1285,1795,1822] 2019-12-20 MG, R L. Ferreira Iceland Lapa D'Agua cave -16.707039 Male 1 -43.920925 Parque Estadual da Lapa Grande 5 89 3 3 paratype