Iansaoniscus leilae, Cardoso & Bastos-Pereira & Ferreira, 2022

Cardoso, Giovanna Monticelli, Bastos-Pereira, Rafaela & Ferreira, Rodrigo Lopes, 2022, Two new troglobitic species of Iansaoniscus from Brazilian caves (Crustacea, Isopoda, Pudeoniscidae), Subterranean Biology 43, pp. 127-143 : 127

publication ID	https://dx.doi.org/10.3897/subtbiol.43.81308
publication LSID	lsid:zoobank.org:pub:AAF4E607-B43C-4797-9903-05BD241F9CF1
persistent identifier	https://treatment.plazi.org/id/4F20CBD9-585B-48BF-9C18-019EFF7B5EEF
taxon LSID	lsid:zoobank.org:act:4F20CBD9-585B-48BF-9C18-019EFF7B5EEF
treatment provided by	Subterranean Biology by Pensoft
scientific name	Iansaoniscus leilae
status	sp. nov.

Treatment

Iansaoniscus leilae sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Scleropactidae sp. nov. [sic!] - Souza-Silva and Ferreira 2016: 9, fig. 3F.

Diagnosis.

Cephalon lateral lobes with straight distal margin; frontal shield triangular with frontal margin directed upwards with antennal socket depressed, vertex margin depressed; pereonite 1 epimeron without dorsolateral furrow; pereonite 1 grooved on ventral margin for two thirds of its length, pereonite 2 with well-developed ventral lobe; telson with acute apex; antennula distal article with two lateral and two apical aesthetascs; uropod exopod slightly shorter than endopod, as long as distal margin of telson.

Material examined.

Holotype: Brazil • 1 male; Bahia state, municipality of Campo Formoso, Toca do Goncalo cave (WGS84 -10.510992, -40.894659); 10th December 2018; RL Ferreira leg.; ISLA 95911 GoogleMaps . Paratypes: • 1 male (mounted in slide), 2 females (1 mounted in slide); same data as holotype; ISLA GoogleMaps 95912. • 1 male, 1 female; 05th January 2008; same location as holotype; ISLA GoogleMaps 95913. • 6 females; 05th January 2008; same location as holotype; ISLA GoogleMaps 95914. • 1 male (mounted in slide), 1 female; municipality of Campo Formoso , Toca da Tiquara cave (-10.458611, -40.542222); RL Ferreira leg.; ISLA GoogleMaps 95917.

Etymology.

The new species is named after Dr. Leila Aparecida Souza, UECE, for her contributions on the systematics of Brazilian subterranean Oniscidea.

Description.

Maximum length: male and female, 6 mm. Body outline in lateral view as in Fig. 1A View Figure 1 , colorless, eyes absent (Fig. 1A-C View Figure 1 ). Cephalon lateral lobes with straight distal margin; frontal shield triangular with frontal margin directed upward with antennal socket depressed, vertex margin depressed (Fig. 1B, C View Figure 1 ). Pereonite 1 epimeron without dorsolateral furrow; pereonite 1 grooved on ventral margin for two thirds of its length, pereonite 2 with well-developed ventral lobe (Fig. 1D-F View Figure 1 ); pereonites 3-7 with sub-quadrangular epimera. Pleonites 3-5 with epimera sub-quadrangular and directed backwards (Figs 1A, G View Figure 1 , 2A View Figure 2 ). Telson (Figs 1G View Figure 1 , 2A View Figure 2 ) slightly wider than long with concave sides, apex acute. Antennula (Fig. 2B View Figure 2 ) with three articles, distal article longer than second article bearing two lateral and two apical aesthetascs. Antenna (Fig. 2C View Figure 2 ) surpassing pereonite 3 when extended backwards, fifth article of peduncle as long as flagellum; flagellum with three articles; second and third articles subequal in length, third article with lateral aesthetascs (Fig. 1H View Figure 1 ). Mandibles (Fig. 2D, E View Figure 2 ) molar penicil with 7-8 branches, left mandible with 2+1 penicils, right with 1+1 penicils. Maxillula (Fig. 2F View Figure 2 ) outer branch with 4 + 5 teeth (two apically cleft); inner branch with two penicils. Maxilla (Fig. 2G View Figure 2 ) with bilobate apex, outer lobe wider than inner lobe, round, covered with thin setae; inner lobe bearing thick setae. Maxilliped (Fig. 2H View Figure 2 ) basis rectangular; palp basal article with two setae distinct in length; endite sub-rectangular, long medial seta, distal margin with two teeth. Pereopods 1-7 (Fig. 3A, B View Figure 3 ) merus and carpus with sparse setae on sternal margin; carpus 1 with longitudinal antennal grooming brush, distal seta apically cleft; dactylus with dactylar organ and ungual setae simple not surpassing outer claw. Uropod (Figs 1G View Figure 1 , 2A View Figure 2 ) protopod longer than wide, with lateral groove; endopod inserted proximally, exopod slightly shorter than endopod, exopod slightly longer than distal margin of telson; proximal margin with lateral groove

Male: Genital papilla (Fig. 3C View Figure 3 ) with triangular ventral shield and subapical orifices. Pleopod 1 (Fig. 3C View Figure 3 ) exopod ovoid, margin straight, almost three times wider than long; endopod four times as long as exopod, distal portion slightly bent outwards, apex with small setae. Pleopod 2 exopod (Fig. 3D View Figure 3 ) triangular bearing one seta on outer margin, endopod flagelliform, almost three times as long as exopod. Pleopod 3-5 exopods as in Fig. 3E-G View Figure 3 .

Habitat and conservation issues.

The Toca do Gonçalo cave presents ca. 500 meters of mapped conduits. It is inserted at the Una geological group of carbonate rocks from the Caatinga Formation, which comprises relatively young rocks deposited around 600 million years ago ( Auler 2019). It is located in the Campo Formoso municipality, Bahia state, Northeastern Brazil, within the Caatinga (a semiarid biome) (Fig. 9 View Figure 9 ). The cave presents a single horizontal lenticular-shaped entrance, 2 m high and 8 m wide (Fig. 4A View Figure 4 ). It has two distinct levels: while the upper level is predominantly dry, the lower level used to be frequently filled with phreatic water (Fig. 4B, C View Figure 4 ). However, as will be discussed further on, several changes (at both local and regional scales) led to a massive reduction in the water table level, thus, exposing several conduits that used to be inaccessible to men in the past decades (Fig. 4C View Figure 4 ). The main food sources for both the terrestrial and aquatic fauna seem to be particulate organic matter from the surface, although there are some root mats in the water table level and small guano piles in some areas within the cave.

Culver and Sket (2000) defined hotspots of subterranean biodiversity as caves (or cave systems) with 20 or more cave-restricted species. The Toca do Gonçalo cave shelters 22 troglobitic species and represents one of the three hotspots of subterranean biodiversity known for South America ( Souza-Silva and Ferreira 2016; Souza-Silva et al. 2021). Most troglobitic species occurring in this cave remain undescribed, with descriptions already known for only seven of them: the beetle Coarazuphium caatinga (Pellegrini & Ferreira, 2014); the cricket Erebonyx catacumbae (Mello & Ferreira, 2021); the palpigrade Allokoenenia canhembora (Souza & Ferreira, 2022); the centipedes Cryptops spelaeoraptor ( Ázara & Ferreira, 2014a) and Newportia spelaea ( Ázara & Ferreira, 2014b); the amphipod Spelaeogammarus trajanoae (Koenemann & Holsinger, 2000); and the isopod Pongycarcinia xyphidiorus ( Messana et al. 2002).

Specimens of I. leilae sp. nov. (Fig. 4D, E View Figure 4 ) were observed at the upper level in the first cave surveys, in the late 1990s. Several specimens were observed, especially near some old bat guano piles. At that moment, most of the lower level was filled with water. Hence, even the upper level was moist due to the influence of the high phreatic level on the whole cave atmosphere. However, local inhabitants use to draw water from the cave (as the region is quite dry) and this practice occurred for decades. This removal occurred manually at the beginning, but a diesel pump (Fig. 4F View Figure 4 ) was installed inside the cave in the 1980s, drying out previously flooded areas ( Prevorčnik et al. 2012; Souza-Silva and Ferreira 2016). It is important to mention that the locals used to remove water from the cave once a week to fill up an external reservoir, hence the water table was persistent. However, in 2010, an electric pump employed by a local farmer for irrigation was installed in the cave (Fig. 4G View Figure 4 ), leading to a pronounced reduction of at least two meters in the water table inside the cave. Even after the removal of this electric pump (in 2012) the water table reduction continued, since artesian wells were built up outside the cave, so the water demand persisted. During a visit to the cave in August 2013, a major reduction in the water level was observed (approximately 3 m compared to the “pristine” level - observed in the 1990s). In 2013, specimens of I. leilae sp. nov. were no longer found in the upper level of the cave (that was extremely dry), being only observed on the moist substrates of the lower level, even though, in lower densities when compared to the first observations. In December 2018, in a visit to the cave, the whole water table was no longer observed, so previously inaccessible areas were explored, revealing the cave to be much longer than previously thought, and only a few cave-restricted species were observed. From the 22 previously observed troglobitic species, only two (one specimen of I. leilae sp. nov., and one springtail) were observed in some moist areas located deep inside the cave in previously flooded areas. The single individual of I. leilae sp. nov. was found in a small piece of wood, apparently attracted by the organic compounds. It is important to mention that this species may be seriously threatened, as other cave-restricted species from the Toca do Gonçalo cave. Urgent intervention by the competent environmental agency is needed to ensure the protection of this hotspot of subterranean biodiversity in South America, especially considering that even the most relevant caves can now be destroyed in Brazil ( Brasil 2022).