Xangoniscus lapaensis Campos-Filho, Gallo & Bichuette, 2022

Campos-Filho 1, Ivanklin S., Gallo 2, Jessica S., Gallao 2, Jonas E., Torres 2, Dayana F., Horta 3, Lilia, Carpio-Diaz 4, Yesenia M., Lopez-Orozco 4, Carlos M., Borja-Arrieta 4, Ricardo, Aguiar 5, Jose O. & Bichuette 2,3, Maria E., 2022, Unique and fragile diversity emerges from Brazilian caves - two new amphibious species of Xangoniscus Campos-Filho, Araujo & Taiti, 2014 (Oniscidea, Styloniscidae) from Serra do Ramalho karst area, state of Bahia, Brazil, Subterranean Biology 42, pp. 1-22 : 1

publication ID	https://dx.doi.org/10.3897/subtbiol.42.75725
publication LSID	lsid:zoobank.org:pub:5C413E74-53FA-4AB0-B4CB-B6A332C83030
persistent identifier	https://treatment.plazi.org/id/855DC7C6-D196-4B19-8340-18DB358A7277
taxon LSID	lsid:zoobank.org:act:855DC7C6-D196-4B19-8340-18DB358A7277
treatment provided by	Subterranean Biology by Pensoft
scientific name	Xangoniscus lapaensis Campos-Filho, Gallo & Bichuette
status	sp. nov.

Treatment

Xangoniscus lapaensis Campos-Filho, Gallo & Bichuette View in CoL sp. nov.

Figures 1 View Figure 1 , 2 View Figure 2 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7

Type locality.

Bahia, Feira da Mata, Gruna Boca da Lapa cave (13°56'46.4"S, 44°11'12.0"W).

Type material.

Holotype male (LES 27734), Bahia, Feira da Mata, Gruna Boca da Lapa cave, 15 October 2020, leg. ME Bichuette, DF Torres, JS Gallo, L Senna-Horta & JE Gallão. Paratypes 1 male (parts in slides), 2 females (LES 27735); 1 male, 3 females (one female with parts in slides) (LES 27736), same data as holotype.

Description.

Body length: ♂ 8.0 mm, ♀ 9.3 mm. Body unpigmented, slightly robust, lateral sides slightly convex (Figs 2C, D View Figure 2 , 4A-C View Figure 4 ). Dorsal surface smooth with scattered fringed scale setae (Fig. 5A View Figure 5 ). Pereonite 1 epimera with distal corners slightly developed frontwards, not surpassing cephalon, posterior corners right-angled; pereonite 2-4 epimera gradually directed backwards, posterior corners progressively more acute; pleon slightly narrower than pereon, pleonites 3-5 epimera well-developed and falciform (Figs 4B View Figure 4 , 5C View Figure 5 ). Cephalon (Figs 4C View Figure 4 , 5B View Figure 5 ) with large quadrangular antennary lobes; vertex with lateral depression to fit antennae when extended backwards, profrons with V-shaped suprantennal line; eyes absent. Telson (Fig. 5C View Figure 5 ) with well pronounced concave sides and broadly rounded apex. Antennula (Fig. 5D View Figure 5 ) of three articles, medial and distal articles subequal in length, second article bearing one long seta on inner margin, distal article with two long apical aesthetascs. Antenna (Fig. 5E View Figure 5 ) with fifth article of peduncle longer than flagellum; flagellum of three articles, first article longest, distal article bearing tuft of free sensilla. Left mandible (Fig. 5F View Figure 5 ) with two penicils, right mandible (Fig. 5G View Figure 5 ) with one penicil and lacinia mobilis leaf-shaped with rounded apex. Maxillula (Fig. 5H View Figure 5 ) outer branch with 5 + 5 teeth, apically entire, and two thick plumose stalks; inner branch with three penicils, proximal one longer than two apical. Maxilla (Fig. 5I View Figure 5 ) with setose and bilobate apex, outer lobe smaller. Maxilliped (Fig. 5J View Figure 5 ) basis enlarged on distal portion bearing fringe of fine setae; first article of palp with two setae, distal articles fused bearing distal tufts of several thin setae; endite rectangular, outer and medial margins setose, apically with two triangular teeth and large rounded penicil. Uropod (Fig. 6A View Figure 6 ) branches inserted at same level, endopod slightly longer than exopod. Pereopods 1-7 gradually elongated, pereopods 1-7 merus, carpus, and propodus bearing sparse setae and fringed scales (discernible over 200 × magnification) on sternal margin, pereopod 7 basis with scales of water conduction system; dactylus of one claw bearing many setae on inner and outer margins.

Male. Pereopods 1-6 (Fig. 6B-G View Figure 6 ) merus with proximal portion bearing fringed scales and thin setae on sternal margin. Pereopod 1 (Fig. 6B View Figure 6 ) carpus with large antennal grooming brush. Pereopod 5 (Fig. 6F View Figure 6 ) slightly depressed on distal sternal margin. Pereopod 6 (Fig. 6G View Figure 6 ) ischium flattened on sternal portion bearing brush of fine setae. Pereopod 7 (Fig. 6H View Figure 6 ) ischium with straight sternal margin, merus and carpus with no distinct modifications. Genital papilla (Fig. 7A View Figure 7 ) lanceolate, enlarged on median portion, apical part narrow. Pleopod 1 (Fig. 7B View Figure 7 ) exopod subtriangular bearing two short setae; endopod longer than exopod, narrow basal article and flagelliform distal article; basipod with triangular medial part fringed with fine and long setae on outer and distal margins, distal margin strongly sinuous. Pleopod 2 (Fig. 7C View Figure 7 ) exopod triangular, median portion narrower, distal margin almost straight bearing three setae; endopod of two thickset articles, second article about three times as long as first, with complex apical part: distal margin subquadrangular with narrow transverse process, subapical triangular lobe strongly folded. Pleopod 3 exopod (Fig. 7D View Figure 7 ) subtriangular, longer than wide, covering pleopods 1 and 2, bearing many short setae, distal external margin straight. Pleopod 4 and 5 exopods (Fig. 7E, F View Figure 7 ) subrectangular, wider than long, with distal portion bearing many short setae.

Etymology.

The new species is named after the locality where the specimens were collected, Gruna Boca da Lapa, an important cave discovered and mapped by Grupo Bambuí de Pesquisas Espeleológicas (GBPE) in 1991 and only now is it studied in relation to its cave fauna.

Remarks.

Xangoniscus lapaensis sp. nov. resembles X. aganju in the shape of the male pleopod 2 endopod; however, it differs in the vertex of the cephalon that lacks a frontal groove, and with a more pronounced suprantennal line that surpasses the antennule insertion (not surpassing in X. aganju ). Also, the male pereopod 6 carpus lacks any modification (strongly modified in X. aganju , see Campos-Filho et al. 2014); the male pleopod 1 exopod is not elongated, and the male pleopod 2 exopod is narrower on inner portion. Moreover, X. lapaensis sp. nov. differs in the uropod endopod slightly longer than exopod (opposite in X. aganju ) and the compact triangular shape of the male pleopod 1 exopod (elongated in X. aganju ).

Ecology and behavior.

Xangoniscus lapaensis sp. nov. occurs in travertine pools fed by infiltration of water through the limestone rock, dripping from the cave ceiling, and in isolated pools along the cave (Fig. 2B, C View Figure 2 ), distributed from the twilight until the aphotic zone, something that demonstrates that its distribution is related to pools formed by infiltration water, i.e., its special habitat is available. The microhabitat is composed of rocky substrate, with little silt and sand sediment. The water is clear, with a very slow current, and a depth varying from 0.05 m to 0.15 m (Fig. 2B-D View Figure 2 ). Physicochemical variables were typical of karst aquifers that have high pH values: pH = 8.5-9.0, T = 23.5 °C, very different from the conditions in the base-level river (pH = 7.5, T = 25 °C). A small quantity of organic and particulate matter was observed in the small pools. Population density in the pools was high, ranging 6.5 to 32 individuals.m-2 and the abundance was 74 individuals in an area of 2.8 m2. The locomotor behavior was very particular, exhibiting fast and effective walking movements when submerged. However, when emerging from water, individuals showed a slow walking behavior on terrestrial substrate (see Supplementary Online Material 1). Xangoniscus lapaensis sp. nov. did not show photophobic behavior (indifferent to flashlight of about 600 lumens), and also seemed to exhibit intraspecific interactions, with no agonistic behavior. Adults and juveniles were observed in the pools, representing possible recruitment at the end of the dry season. It appears that X. lapaensis sp. nov. occurs preferentially in microhabitats fed by infiltration water, since no individual was recorded in the stream of the cave, a base-level river. This is very specific and unique, and probably the main habitat of this species is the spaces in the rocks filled by water.