Pectenoniscus santanensis, Ferreira, 2020

Ferreira, Giovanna Monticelli Cardoso Rafaela Bastos-Pereira Leila Aparecida Souza Rodrigo Lopes, 2020, New cave species of Pectenoniscus Andersson, 1960 (Isopoda: Oniscidea: Styloniscidae) and an identification key for the genus, Nauplius (e 2020039) 28, pp. 1-30 : 17-19

publication ID	https://doi.org/10.1590/2358-2936e2020039
persistent identifier	https://treatment.plazi.org/id/875F1C5E-FFC1-FFDE-FC3D-FB3FFB2DF900
treatment provided by	Felipe
scientific name	Pectenoniscus santanensis
status	sp. nov.

Treatment

Pectenoniscus santanensis View in CoL n. sp.

( Figs. 14–16 View Figure 14 View Figure 15 View Figure 16 , 21 View Figure 21 , 22E View Figure 22 )

Zoobank: urn:lsid:zoobank.org:act:0DB726B3-9C0D-4912-846A-8F2E9AC553F8

Typematerial. Holotype:male( ISLA 77532)(slide), Bahia , Santana, Gruta do Padre cave (-13.216325º -44.065194º), 18 July 2019, leg. R. L. Ferreira . Paratype. 1 female ( ISLA 77533), same locality as holotype, 18 July 2019, leg. R. L. Ferreira .

Diagnosis. Antennula with six aesthetascs; male pleopod 1 exopod triangular, with lateral margin straight and round apex; male pleopod 2 exopod subtriangular; and male pleopod 2 endopod twisted and apex forked.

Description. Maximum length: male, 2 mm. Colorless, eyes absent ( Figs. 14A View Figure 14 , 16D View Figure 16 ). Dorsal scale-setae tricorn-shaped ( Fig. 14B View Figure 14 ). Dorsal granulations in two rows on pereonites 1 to 7, smooth pleon ( Fig. 14A,C View Figure 14 ). Cephalon with round antennal lobes; supra-antennal line bent in middle ( Fig. 14B View Figure 14 ). Pereonite 1 with margin projected forward, not surpassing median portion of cephalon; pereonites 4–7 posterior margin progressively more concave; pleonites 3–5 epimera posterior points slightly developed; pleon narrower than pereon ( Fig. 14A View Figure 14 ). Pleotelson with concave margin and round apex ( Fig.14C View Figure 14 ). Antennula with three articles, distal article with six aesthetascs ( Fig. 14D View Figure 14 ). Antenna surpasses pereonite 1 when extended backward, fifth article of peduncle shorter than flagellum, with one seta as long as first flagellum article; f lagellum with three articles ( Fig. 14E View Figure 14 ). Left mandible with two penicils ( Fig.14F View Figure 14 ); right mandible with one penicil, lacinia mobilis leaf-shaped ( Fig.14G View Figure 14 ). Maxillula outer branch with 4+5 teeth, apically entire, and two plumose setae; inner branch with three penicils ( Fig.14H View Figure 14 ). Maxilla with bilobate apex, inner lobe wider than outer lobe with several setae on distal margin ( Fig.14I View Figure 14 ). Maxilliped basis enlarged on distal portion; palp with two setae; endite triangular, apex with one penicil and two spines ( Fig.14J View Figure 14 ). Pereopod 1 antennal grooming brush composed of serrated scale setae on propodus and on sternal margin of carpus ( Fig. 15A View Figure 15 ); dactylar seta bifid with thin setule. Uropod protopod rectangular, longer than distal margin of pleotelson; exopod longer than endopod, inserted distally ( Fig. 14C View Figure 14 ).

Male: Pereopods 6 and 7 ( Fig. 15B, C View Figure 15 ) propodus with tufts of setae on tergal margin, with water conducting system; pereopod 7 ischium with straight sternal margin ( Fig. 15C View Figure 15 ). Genital papilla ( Fig. 15D View Figure 15 ) with medial portion slightly enlarged with narrow apex. Pleopod 1 ( Fig. 15D View Figure 15 ) protopod rectangular, three times wider than long; exopod triangular, with lateral margin straight and round apex; endopod more than twice longer than exopod. Pleopod 2 ( Fig. 15E View Figure 15 ) protopod rectangular; exopod subtriangular, almost twice wider than long; endopod with distal article three times longer than proximal article, twisted, apex forked (two distal projections, one directed backward and one outward). Pleopod 3–5 exopods ( Fig.15F–H View Figure 15 ) subquadrangular, bearing four-five setae on outer margin.

Etymology. The specific epithet “ santanensis ” refers to municipality of Santana, where the new species was collected.

Remarks. Pectenoniscus santanensis n. sp. differs from P.angulatus and P. liliae by the dorsal granulation pattern (two rows in all the pereonites versus three rows in the first pereonite and two in the others on P. angulatus and P. liliae ), the number of aesthetascs on antennula (6 versus 8 in P. angulatus and 9 in P. liliae ), the sternal margin of male pereopod 7 ischium (straight versus with triangular projection in P. angulatus and convex in P. liliae ), the shape of male pleopod 2 exopod (sub-triangular versus rectangular in P. angulatus and ovoid in P. liliae ) and the orientation of male pleopod 2 endopod (twisted versus straight in P.angulatus and P. liliae ). Pectenoniscus santanensis n. sp. is similar to P. carinhanhensis n. sp. in the shape of male pleopod 2 exopod subtriangular and by the straight sternal margin of male pereopod 7 ischium; however it differs by the number of aesthetascs on antennula (6 versus 11 in P. carinhanhensis n. sp.) and the shape of male pleopod 1 exopod (straight lateral margin versus sinuous in P. carinhanhensis n. sp.).

Habitat and ecological remarks. Gruta do Padre represents one of the largest known caves in Brazil (16,400 meters of horizontal projection – Fig. 16A View Figure 16 ), currently considered the fifth longest in total extension in the country ( Rubbioli et al., 2019) and is part of one of the most extensive subterranean hydrological systems in Brazil. It presents three distinct levels with a river flowing in the lowest one ( Fig.16C View Figure 16 ). The upper level is accessed through the cave main entrance ( Fig. 16B View Figure 16 ), and is connected to a set of ample galleries, most of which were enlarged by collapsing processes. The specimens were found on the f loor, walking on a moist mud layer, in a voluminous chamber located in a deep portion of the upper level, around 500 meters from the main cave entrance ( Fig.16D View Figure 16 ). Although far from the river, the substrates were moist due to the high humidity in the chamber provided by dripping speleothems. Considering the huge dimensions of the cave, a thorough search was only performed in few areas, therefore the low number of registered specimens (less than 10 – some of them were not collected) does not necessarily indicate that the species present low population density. Gruta do Padre cave also presents other described troglobitic species, such as the beetle Coarazuphium tessai ( Godoy and Vanin, 1990) , the amphipod Spelaeogammarus santanensis Koenemann and Holsinger, 2000 and the millipede Phaneromerium cavernicolum Golovatch and Wytwer, 2004 . Currently, the external environment surrounding the cave is altered, especially by the removal of the native vegetation for pastures ( Figs. 21 View Figure 21 , 22E View Figure 22 ). On the other hand, considering the huge extension of the cave and the fact that only a few speleologists visit it each year (especially due to the difficult accesses inside the cave), the inner portion of the cave is well preserved.