Benthana xiquinhoi Campos-Filho, Bichuette & Taiti, 2019

Campos-Filho, Ivanklin Soares, Fernandes, Camile Sorbo, Cardoso, Giovanna Monticelli, Bichuette, Maria Elina, Aguiar, José Otávio & Taiti, Stefano, 2019, Two new species and new records of terrestrial isopods (Crustacea, Isopoda, Oniscidea) from Brazilian caves, Zootaxa 4564 (2), pp. 422-448 : 434-438

Benthana xiquinhoi Campos-Filho, Bichuette & Taiti sp. n.

Figs 11–13 , 18D

Zoobank. urn:lsid:zoobank.org:act:F4730822-4853-4CE3-8F20-0C5E9DD0D7F3 .

Philosciidae indet 2 Gallão & Bichuette, 2018: 12, table 2.

Etymology. The new species is named after Raimundo Cruz do Santos, also called ‘Xiquinho’, for his great contribution to cave surveys and his enthusiasm for cave fauna and discoveries.

Material examined. Holotype Bahia, Andaraí, Povoado de Igatu: male ( LES 6353 ), Gruna Parede Vermelha cave , 12°52’41”S, 41°18’57”W, 2 April 2013, leg. M.E. Bichuette, J.E. Gallão and D.M. von Schimonsky. Paratypes: 2 males ( LES 6352 ) (parts in micropreparations), same data as holotype ; 1 female ( LES 6335 ), same locality, 31 May 2010, leg. M.E. Bichuette, B. Rantin, J.E. Gallão and L. B. Simões ; 1 female (parts in micropreparations) ( LES 6337 ), same locality, 29 October 2010, leg. M.E. Bichuette and J. E. Gallão ; 1 female ( LES 6342 ), Gruna Veio de Aurélio cave , 12°51’36”S, 41°18’11”W, 28 October 2010, leg. M.E. Bichuette and J. E. Gallão ; 2 females, 1 juvenile ( LES 6348 ), Gruna Lava Pé cave , 12°53’42”S, 41°19’04”W, 30 March 2013, leg. M.E. Bichuette, J. E. Gallão and D.M. von Schimonsky.

Description. Maximum body length: male 9.5 mm, female 10.5 mm. Colour light brown: cephalon with irregular unpigmented spots; pereonites 1–7 weakly pigmented on medial portion, epimera more pigmented; pleonites 1–5 with unpigmented spots on medial portion, pleonites 3–5 more pigmented on paramedian and median portions; telson pigmented.

Body convex, outline as in Fig. 11A . Dorsal surface smooth bearing few long triangular scale-setae ( Fig. 11B ). Noduli laterales long, one line per side with d/c coordinates reaching a maximum on pereonite 4; b/c coordinates gradually decreasing ( Fig. 11C, D ). Cephalon ( Fig. 11E ) with suprantennal line bent downwards in middle, no frontal line and lateral lobes; eyes composed of 10–12 small ommatidia arranged in four rows. Pereonites 1–4 with postero-lateral corners right-angled with rounded apices and posterior margins straight; pereonites 5–7 with postero-lateral corners gradually more acute and posterior margins gradually more arched. Pleon narrower than pereon, pleonites 3–5 with epimera triangular, acute, and directed backwards ( Fig. 11A ). Telson ( Fig. 11F ) triangular, lateral sides straight and apex broadly rounded.

Antennula ( Fig. 11G ) of three articles, distal article longest bearing seven lateral aesthetascs plus apical pair. Antenna ( Fig. 11H ) very long, reaching pereonite 4 when extended backwards, distal article of peduncle longer than flagellum; flagellum of three articles, proximal article longest, apical organ short bearing two long sensilla.

Mandibles with molar penicil of eight branches and dense cushion of setae, left mandible ( Fig. 12A ) with 2+1 penicils, and right mandible ( Fig. 12B ) with 1+1 penicils. Maxillula ( Fig. 12C ) outer endite with two penicils, distal margin rounded; outer endite with 4+6 teeth, five of them pectinate, one short and simple. Maxilla ( Fig. 12D ) outer lobe twice as wide as inner lobe with distal margin sinuous, covered with thin setae; inner lobe rounded covered with thick setae. Maxilliped ( Fig. 12E ) with rectangular basis with sparse setae; endite rectangular, distal margin slightly sinuous, medial seta surpassing distal margin, two hooks on distal margin, longitudinal ridge bearing dense setae ending with one short triangular seta; proximal article of palp with two stout setae.

Pereopods rather slender, bearing distal fringe of hyaline scales on merus and carpus; carpus 1 with transverse antenna-grooming brush and distal seta with hand-like apex; dactylus with inner claw reaching distal margin of outer claw, dactylar and ungual setae simple, not surpassing outer claw.

Uropod ( Fig. 13A ) protopod subquadrangular, protopod and exopod grooved on outer margin bearing glandular pores, exopod twice as long as endopod, endopod inserted proximally.

Pleopod exopods with Benthana - type respiratory areas.

Male. Pereopods 1–3 ( Fig. 13B ) merus and carpus with brushes of setae on sternal margin. Pereopod 7 ( Fig. 13C ) without sexual dimorphism. Genital papilla ( Fig. 13D ) with triangular ventral shield and two subapical orifices. Pleopod 1 ( Fig. 13E ) exopod heart-shaped, elongated (ratio z:y= 2.15), lateral protrusion prominent with acute apex, distal margin straight; endopod longer than exopod, stout and straight, distal portion with line of short setae. Pleopod 2 ( Fig. 13F ) exopod triangular, outer margin concave with two setae; endopod slender, distinctly longer than exopod. Pleopods 3 and 4 exopods as in Fig. 13G and H , respectively. Pleopod 5 exopod ( Fig. 13I ) triangular, outer margin almost straight with five setae.

Remarks. The genus Benthana comprises 28 species mainly distributed in the Atlantic Forest areas of Brazil, with Benthana picta ( Brandt, 1833) occurring also in Paraguay ( Campos-Filho et al. 2015). Only two species were previously recorded from cave habitats, the troglobiont B. iporangensis Lima & Serejo, 1993 from Ressurgência das Areias de Água Quente and Areias de Cima caves (Areias system), and Gruta do Tatu cave, all included in conservation units in the state of São Paulo, and the non-troglomorphic and probably trogloxene B. taeniata Araujo & Buckup, 1994 from Gruta Zeferino I, state of Minas Gerais (Campos-Filho et al. 2014, 2015). Those caves are located in Chapada Diamantina region at the boundaires of Caatinga vegetation and surrounded by remains of the Atlantic forest and “campos rupestres” vegetation, a variation of Cerrado, not as dry as Caatinga ( Fig. 2C, D ). The new species occurs in very humid sandy (unconsolidated) or rocky substrate with organic matter (mainly moss close to creeks inside caves), showing medium abundance and densities (lower <0.5 inds/m 2) ( Fig. 18D ). The new species is considered to be troglobiotic.

Benthana xiquinhoi sp. n. is similar to B. picta in the shape of the male pleopod 1 exopod; it is readily distinct in the reduced number of ommatidia, 10–12 (vs. 24 in B. picta ), telson with distal margin rounded (vs. triangular), mandibles with eight branches on molar penicil (vs. 12), uropod exopod longer than endopod (vs. subequal), male pleopod 1 endopod straight (vs. bent outward s). Only Benthana schubarti Lemos de Castro, 1958 and B. iporangensis show eyes with reduced number of ommatidia, 16 and 18, respectively; Benthana xiquinhoi sp. n. distinctly differs from those species in the shape of the male pleopod 1 exopod (see Campos-Filho et al. 2015).

Figures

FIGURE 2. A, area surrounding Chico Pernambuco cave indicating disturbance activities, artisanal charcoal production (photo: M.E. Bichuette); B, area surrounding Domingão cave with Caatinga vegetation and pasture activity (photo: M.E. Bichuette); C, Campos rupestres vegetation near sandstone caves in Povoado de Igatu (photo: M.E. Bichuette); D, gallery of Gruna Lava Pé cave (Igatu) with a small stream where Benthana xiquinhoi Campos-Filho, Bichuette & Taiti sp. n. occurs (photo: J.E. Gallão).

FIGURE 11. Benthana xiquinhoi Campos-Filho, Bichuette & Taiti sp. n., female paratype, LES 6337: A, habitus, dorsal view; B, dorsal scale-seta; C, noduli laterales d/c coordinates; D, noduli laterales b/c coordinates; E, cephalon, frontal view; F, pleonites 4 and 5 and telson; G, antennula; H, antenna.

FIGURE 12. Benthana xiquinhoi Campos-Filho, Bichuette & Taiti sp. n., female paratype, LES 6337: A, left mandible; B, right mandible; C, maxillula; D, maxilla; E, maxilliped.

FIGURE 13. Benthana xiquinhoi Campos-Filho, Bichuette & Taiti sp. n., female paratype, LES 6337: A, uropod. Male paratype, LES 6352: B, pereopod 1; C, pereopod 7; D, genital papilla; E, pleopod 1; F, pleopod 2; G, pleopod 3 exopod; H, pleopod 4 exopod; I, pleopod 5 exopod.

FIGURE 18. A–C, Xangoniscus aganju Campos-Filho, Araujo & Taiti, 2014 (photos: P.P. Rizzato and M.E. Bichuette); D, Benthana xiquinhoi Campos-Filho, Bichuette & Taiti sp. n. (photo: J.E. Gallão).