Xangoniscus lundi,

Cardoso, Giovanna Monticelli, Bastos-Pereira, Rafaela, Souza, Leila Aparecida & Ferreira, Rodrigo Lopes, 2020, New troglobitic species of Xangoniscus (Isopoda: Styloniscidae) from Brazil, with notes on their habitats and threats, Zootaxa 4819 (1), pp. 84-108: 85-88

publication ID

https://doi.org/10.11646/zootaxa.4819.1.4

publication LSID

lsid:zoobank.org:pub:AB417537-CE48-465A-8C23-5AF0B7602ADC

persistent identifier

http://treatment.plazi.org/id/E55C87AB-FFB5-1A28-C29F-FABBFCB6F83F

treatment provided by

Plazi

scientific name

Xangoniscus lundi
status

n. sp.

Xangoniscus lundi  n. sp.

Figs. 1–4View FIGURE 1View FIGURE 2View FIGURE 3View FIGURE 4, 19AView FIGURE 19

Material examined. Holotype: Male ( ISLA 77511), Minas Gerais , Montes Claros , Parque Estadual da Lapa Grande, Lapa Grande cave, 16.706672ºS, 43.942910ºW, 2 April 2015, leg. R. L. FerreiraGoogleMaps  . Paratypes: 10 males, 11 females, same data as holotype ( ISLA 14338)GoogleMaps  ; 1 male, same location as holotype, 20 December 2019 ( ISLA 14337)GoogleMaps  .

Etymology. The specific epithet honors the Danish naturalist Peter Wilhelm Lund, who worked for decades in the caves of Minas Gerais state, and made remarkable contributions to Brazilian paleontology, being considered the founder of speleology as a science in Brazil. Furthermore, we extend the honor to a caving group of the same name (Espeleo Grupo Peter Lund) for their contributions to enhance the knowledge regarding the caves in the northern Minas Gerais state, as well as the support given to us during our collections in the area.

Diagnosis. Pleopod 1 exopod triangular with prominent apex and sinuous margin, pleopod 2 exopod triangular with round distal margin and endopod distal article wrench-like with transverse pointed process on apex and lateral membrane.

Description. Maximum length: male, 5.5 mm. Colorless, eyes absent ( Figs. 1AView FIGURE 1, 3AView FIGURE 3, 4CView FIGURE 4, 19AView FIGURE 19). Dorsal surface smooth with scattered simple and fringed scale-setae ( Figs. 1AView FIGURE 1, 3BView FIGURE 3). Cephalon ( Fig. 1BView FIGURE 1) with small antennary lobes; profrons with V-shaped suprantennal line. Posterior corners of pereonites progressively directed backwards, pereonite 7 not surpassing distal margin of pleonite 2; pleonites 3–5 epimera posterior point not developed; pleon narrower than pereon ( Figs. 1AView FIGURE 1, 19AView FIGURE 19). Telson ( Fig. 1CView FIGURE 1) with concave sides, rounded apex.

Antennula ( Fig. 1DView FIGURE 1) with three articles, second article shortest, distal article with three short apical aesthetascs. Antenna ( Fig. 1A, 1EView FIGURE 1) surpasses pereonite 1 when extended backwards, fifth article of peduncle and flagellum subequal in length; flagellum with four articles. Left mandible with two penicils ( Fig. 1FView FIGURE 1), right mandible with one penicil, lacinia mobilis leaf-shaped ( Fig. 1GView FIGURE 1). Maxillula ( Fig. 1HView FIGURE 1) outer branch with 5 + 5 teeth, apically entire, and two thick plumose stalks; inner branch with three penicils. Maxilla ( Fig. 1IView FIGURE 1) with bilobate apex, inner lobe wider than outer lobe with several setae on distal margin. Maxilliped ( Fig. 1JView FIGURE 1) 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 strong teeth.

Pereopod 1 antennal grooming brush composed by serrated scale setae longitudinally on propodus and on sternal margin of carpus. Uropod ( Fig. 2AView FIGURE 2) protopod longer than distal margin of telson; endopod and exopod subequal in length, exopod with proximal insertion.

Male. Pereopods 1–6 ( Fig. 2View FIGURE 2 B–D) merus with scales on sternal margin. Pereopod 4 ( Fig. 2CView FIGURE 2) propodus anterior margin concave and distal margin with fringed scales. Pereopods 5 and 6 ( Fig. 2DView FIGURE 2) merus enlarged with distal margins almost two times wider than proximal one, wider than long, dactylus with setae on sternal margin. Pereopod 7 ( Fig. 2EView FIGURE 2) basis with scales of water conduction system, with no distinct modifications. Genital papilla ( Fig. 2FView FIGURE 2) lanceolate. Pleopod 1 ( Fig. 2GView FIGURE 2) exopod triangular with prominent apex, sinuous distal margin and covered by fine setae; endopod longer than exopod, with narrow basal article and flagelliform distal article; protopod distal margin shorter than exopod. Pleopod 2 ( Fig. 2HView FIGURE 2) exopod subtriangular, round distal margin, bearing one seta; endopod of two articles, basal article rectangular, shorter than exopod, distal article wrench-like, transverse pointed process on apex, directed outwards, with lateral membrane. Pleopod 3 exopod ( Fig. 2IView FIGURE 2) ovoid, distal margin setose slightly concave. Pleopod 4 exopod ( Fig. 2JView FIGURE 2) rhomboidal wider than long, with distal margin rounded and setose. Pleopod 5 exopod ( Fig. 2KView FIGURE 2) ovoid.

Remarks. By the number of articles on antennal flagellum (four), X. lundi  n. sp. resembles X. odara  and X. itacarambiensis  , since X. aganju  presents three articles. Regarding the shape of male pleopods, in X. lundi  n. sp. the pleopod 1 exopod is triangular while in X. aganju  and X. odara  is subtriangular, and in X. itacarambiensis  is trapezoidal; by the subtriangular shape of male pleopod 2 exopod, X. lundi  n. sp. is distinct from other species, since in X. aganju  the exopod is trapezoidal and in X. odara  and X. itacarambiensis  the exopod is triangular. By the uropods, with endopod and exopod subequal in length, X. lundi  n. sp. is similar to X. itacarambiensis  , since in X. aganju  the exopod is longer than the endopod, and in X. odara  the exopod is shorter than the endopod.

Habitat and threats. Lapa Grande cave is the only known habitat of X. lundi  n. sp. until the present. This cave has 2,200 m of horizontal projection with a labyrinthine morphology ( Fig. 4AView FIGURE 4). Although most part of the cave is extremely dry, there is an intermittent drainage in the innermost and lower part of the cave (around 300 m far from the entrance) ( Fig. 4DView FIGURE 4). Specimens of X. lundi  n. sp. were only found in this drainage, associated with submerged trunks and branches ( Fig. 4E, FView FIGURE 4). During the dry periods the water flow is interrupted and many ponds are formed along this conduit. Non-troglobitic fishes are observed (especially catfishes) in some of them, where no isopods were found. Conversely, the ponds where X. lundi  n. sp. was observed were devoid of fishes. Since no visits were made to the cave during the rainy periods, their distribution within this habitat in such season is unknown, especially considering that fishes would be able to access the whole drainage, thus offering a potential predation pressure.

Lapa Grande cave was severely impacted during the last two centuries. During the 19 th century, the cave was heavily excavated to remove saltpeter (used to produce gunpowder), as several conduits and chambers of the upper level presents clear signs of such diggings. From the 20 th century onwards, the cave passed to be frequently visited by tourists, which produced, during decades, a massive quantity of graffiti, especially on the upper (and drier) levels. Fortunately, due to the relatively small dimensions of the conduit trespassed by the drainage, such region of the cave was poorly visited over time, what made it quite preserved. Currently, tourists can only visit the entrance chamber, where a footbridge was installed ( Fig. 4BView FIGURE 4). Hence, visitors are only allowed in deeper portions of the cave for scientific purposes. Lapa Grande cave is located within the limits of the Parque Estadual da Lapa Grande (named after this cave), hence it is currently inserted in a protected area.

R

Departamento de Geologia, Universidad de Chile