Research Article |
Corresponding author: Carlos Mario López-Orozco ( clopezo1610@gmail.com ) Academic editor: Fabio Stoch
© 2024 Carlos Mario López-Orozco, Ricardo Borja-Arrieta, Yesenia Margarita Carpio-Díaz, Jonas Eduardo Gallão, Ivanklin Soares Campos-Filho, Maria Elina Bichuette.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
López-Orozco CM, Borja-Arrieta R, Carpio-Díaz YM, Gallão JE, Campos-Filho IS, Bichuette ME (2024) Describing to preserve – three new species of Xangoniscus (Oniscidea, Styloniscidae) of unprotected caves in dry areas from Bahia state, northeastern Brazil. Subterranean Biology 50: 79-104. https://doi.org/10.3897/subtbiol.50.139914
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Three new troglobitic amphibious species of Xangoniscus (Styloniscidae) have been described from limestone caves of the Bambui Group semiarid ecosystems (Chacoan subregion) in the state of Bahia: Xangoniscus antiquus sp. nov., X. chaimowiczi sp. nov., and X. jonasi sp. nov. Natural history information is provided for X. chaimowiczi sp. nov. and X. jonasi sp. nov. Considering the differences between the known species of Xangoniscus and those described in this study, we redefined the diagnostic characteristics of the genus. Moreover, the distribution of Xangoniscus is discussed. The species described in this study, along with those previously reported, serve as fundamental tools for decision-making processes aimed at conserving Brazil’s speleological natural heritage.
Amphibious Oniscidea, Cerrado, Caatinga, troglobitic, woodlice
Terrestrial isopods (Oniscidea) are among the most diverse groups within the order Isopoda, comprising more than 4,000 species across 38 or 39 families in more than 500 genera (
In Brazil, more than 50% of terrestrial isopod species are found in caves, highlighting the significant potential of this subterranean habitat (
Within the Oniscidea, the family Styloniscidae comprises 128 species in 17 genera, exhibiting a broad distribution and inhabiting a wide range of terrestrial environments, including caves (
In the present work, three new species of Xangoniscus are described from caves in the state of Bahia, northeastern Brazil. We also discuss aspects of the morphology, distribution, and conservation of the species in the genus.
The specimens were collected from three limestone caves of the Bambui Geomorphological Group located in the southwest of the state of Bahia, between the Caatinga and Cerrado (savannah-like) biomes (Fig.
The Gruna da Serra Solta cave (Fig.
Specimens were collected by hand and stored in 75% ethanol, and identifications were based on morphological characteristics using micropreparations in Hoyer’s medium (
The material examined is deposited in the Collection of the Laboratório de Estudos Subterrâneos (LES, curator: M. E. Bichuette), Universidade Federal de São Carlos, São Carlos, Brazil, and in the collection of the Museu de Zoologia, Universidade de São Paulo, São Paulo, Brazil (
Suborder Oniscidea Latreille, 1802
Family Styloniscidae Vandel, 1952
Xangoniscus aganju Campos-Filho, Araujo & Taiti, 2014 by original designation and monotypy.
Holotype
• 1 male (
Maximum body length: male 10.2 mm, female 6.5 mm. Body outline as in Figs
Male. Pereopods 1–6 (Fig.
The new species is named after Dr. Flavio Chaimowicz, for his important contributions to the knowledge of the Brazilian speleology, who collected the specimens.
Presently known only from Gruta do Padre cave in the state of Bahia, northeastern Brazil (Fig.
The genus Xangoniscus includes 10 amphibious troglobitic species, with a distribution restricted to caves of the Bambui Geomorphological Group between the northeast and southeast regions of Brazil in the states of Bahia and Minas Gerais. Currently, the genus is well defined morphologically, and the main characteristic is the complex shape of the apex of the endopod of pleopod 2 in males. Xangoniscus chaimowiczi sp. nov. differs from all other species of the genus in having the antennula with twelve long aesthetascs (vs. two in X. aganju Campos-Filho, Araujo & Taiti, 2014, X. lapaensis Campos-Filho, Gallo & Bichuette, 2022, and X. odara Campos-Filho, Bichuette & Taiti, 2016, three in X. ibiracatuensis Bastos-Pereira, Souza & Ferreira, 2017, X. lundi Cardoso, Bastos-Pereira, Souza & Ferreira, 2020, and X. santinhoi Cardoso, Bastos-Pereira, Souza & Ferreira, 2020, four in X. dagua Cardoso, Bastos-Pereira, Souza & Ferreira, 2020, four or five in X. ceci Cardoso, Bastos-Pereira, Souza & Ferreira, 2020, five in X. loboi Campos-Filho, Gallão & Bichuette, 2022, six in X. itacarambiensis Bastos-Pereira, Souza & Ferreira, 2017), pereopod 5 carpus with tiny lobe in proximal margin (vs. absent in all species), pereopod 6 carpus enlarged (vs. not enlarged in all species), and pereopod 6 propodus with longitudinal furrow (vs. absent in all species) (
Xangoniscus chaimowiczi
sp. nov. inhabits various areas of the Gruta do Padre cave. Specimens were collected from the river, specifically within the conducto das plaquetas, where they were found living in the sediment. It also inhabits travertine ponds inside the cave. This latter behaviour has been documented in several other Xangoniscus species (Cardoso et al. 2020;
Xangoniscus chaimowiczi López-Orozco, Borja-Arrieta & Campos-Filho, sp. nov. Male A habitus, dorsal view B dorsal scale-seta C cephalon, frontal view D telson and uropod E antennula F antenna G left mandible H right mandible I maxillula J maxilla K maxilliped, arrow illustrating the endite in caudal view.
Holotype • 1 male (parts in slides) (LES 0030097), Bahia, Carinhanha, Gruna da Serra Solta cave, -13.510573, -43.75207, 24 October 2023, leg. JE Gallão.
Maximum body length: male 6.5 mm. Body outline as in Figs
Male. Pereopod 1 (Fig.
The new species is named after Jonas Kahnwald, the protagonist of the “Dark” series, who explores caves to travel through time and space. The epithet “jonasi” is a tribute to the isolation and sense of separation from time and space that caves represent, evoking the central theme of “Dark”. The species reflects extreme adaptation to dark depths, just as Jonas adapts to the complexities and paradoxes of time.
Presently known only from Gruna da Serra Solta cave in the Serra do Ramalho karst area, state of Bahia, northeastern Brazil (Fig.
Xangoniscus jonasi sp. nov. differs from all other species of the genus in having the antennula with eight long aesthetascs (vs. two in X. aganju, X. lapaensis, and X. odara, three in X. ibiracatuensis, X. lundi and X. santinhoi, four in X. dagua, four or five in X. ceci, five in X. loboi, six in X. itacarambiensis, twelve in X. chaimowiczi sp. nov.), pleopod 1 basipod distal margin semicircular apex, longer than exopod (vs. simples and shorter than exopod in X. lundi, X. dagua, X. ceci, X. ibiracatuensis, X. itacarambiensis, X. loboi, X. odara, X. santinhoi, acute and longer than exopod in X. chaimowiczi sp. nov., X. lapaensis and X. aganju).
The species showed low abundance (only one individual caught along the cave). The only individual of X. jonasi sp. nov. captured was found in the aphotic zone on a very wet, muddy substrate, under the cracks formed by the stream current, just a few meters from a pond (Fig.
Xangoniscus jonasi López-Orozco, Bichuette & Campos-Filho, sp. nov. Male A habitus, dorsal view B dorsal scale-seta C cephalon, frontal view D telson and uropod E antennula F antenna G left mandible H right mandible I maxillula J maxilla K maxilliped, arrow illustrating the endite in caudal view.
Holotype
• 1 male (
Maximum body length: male 7.8 mm. Body outline as in Figs
Male. Pereopods 1–6 (Fig.
Latin, antiquus = old. The new species name refers to the long period of time that the samples remained preserved until their description. Perhaps this material represents the first specimens of Xangoniscus collected in Brazil.
Presently known only from Gruta da Represa cave, in the state of Bahia, northeastern Brazil (Fig.
Xangoniscus antiquus sp. nov. resembles X. chaimowiczi sp. nov. in the modifications on male pereopods and number of articles on flagellum of antenna; however, it differs in the number of aesthetascs on antennula (eight vs. twelve in X. chaimowiczi sp. nov.), telson apex (almost straight vs. rounded apex in X. chaimowiczi sp. nov.), and basipod distal margin (semicircular apex, slightly longer than exopod vs. acute apex, longer than exopod in X. chaimowiczi sp. nov.).
Xangoniscus antiquus López-Orozco, Carpio-Díaz & Campos-Filho, sp. nov. Male A habitus, dorsal view B dorsal scale-seta C cephalon, frontal view D telson and uropod E antennula F antenna G left mandible H right mandible I maxillula J maxilla K maxilliped, arrow illustrating the endite in caudal view.
The genus Xangoniscus was erected by
Species of the genus Xangoniscus have been recorded in travertine pools and streams formed by infiltration of water, inhabiting microhabitats composed of rocky substrates, silty sediment, sand, and decomposing plant material (
Regarding the current distribution of the genus Xangoniscus, it is restricted to limestone caves of the Bambui Geomorphological Group located within semiarid environments of the Chacoan subregion, in the biogeographic provinces of Cerrado, Caatinga, and Southern Espinhaco (sensu Morrone et al. 2014,
Among the three species described here, Xangoniscus now includes 13 troglobitic amphibious species, making it the second most species-rich genus of Styloniscidae in Brazil. Among these species, only five are found in national conservation units in Minas Gerais (X. dagua, X. itacarambiensis, X. lundi, X. odara, and X. santinhoi) (Fig.
We would like to thank Dr. Marcos Tavares and Joana d’Arc de Jesus Pinto of