Pectenoniscus fervens Campos-Filho, Taiti & Bichuette sp. nov.

Figs 1, 2C, D, 4D, E, 7, 8

Material examined.

Brazil ● 1♂ (parts in micropreparations), holotype, Gruta Toca Coroa do Frade, Coronel José Dias, Barra Bonita karst region, Casa Nova geomorphological group, state of Piauí, 8°47'51.58"S, 42°25'1.47"W, 8.I.2018, leg. DM Schimonsky, DF Torres and JE Gallão, LES 22421 ● 6♀♀ (one with parts in micropreparations), paratypes, same data as for holotype, LES 27764 .

Description.

Maximum length: ♂ and ♀ 3 mm. Dorsal surface granulated, granules on pereonites 1-7 in two transverse rows, on pleonites 3-5 in one row (Fig. 4D, E). Dorsal scale-setae tricorn-shaped in middle segments (Fig. 7A). Cephalon (Figs 4F, 7B) with antennary lobes small, triangular and slightly directed outwards; profrons with suprantennal line bent downwards medially. Pereonites 1 and 2 epimera with postero-lateral corners rounded, 4-7 progressively directed backwards and more acute (Fig. 4D, E). Pleonites 3-5 epimera without glandular pores (Fig. 7C). Telson (Fig. 7C) twice as wide as long, with concave sides and rounded apex. Antennula (Fig. 7D) with distal article longer than second and first, and bearing at least six aesthetascs plus distal tip. Antenna (Fig. 7E) with fifth article of peduncle slightly longer than flagellum, bearing one distal strong seta; flagellum of four articles, first and second articles subequal in length, third and fourth articles shorter; apical organ longer than distal article of flagellum. Mandibles as in Fig. 7F, G; right mandible with leaf-like lacinia mobilis. Maxillula (Fig. 7H) inner endite with apical penicil robust; outer endite of 4+5 teeth, apically simple, one subapical slender stalk near medial margin. Maxilla as in Fig. 7I. Maxilliped (Fig. 7J) basis with lateral sides fringed with fine setae; palp with first article bearing two setae, distal articles fused and bearing distal fringe of fine setae; endite much longer than wide, lateral margins covered with fine setae, distal margin bearing two strong setae and one elongated penicil. Grooves and scales for water conducting system on ischium, merus, carpus and propodus of pereopod 6 and basis of pereopod 7 (Fig. 8B). Dactylus with ungual seta simple and dactylar seta simple and apically setose. Uropod (Fig. 8A) protopod and exopod not grooved on sternal margin; exopod longer than endopod and inserted almost at same level.

Male. Pereopods 1-7 (Fig. 8B, C) without any sexual modifications. Genital papilla as in previous species. Pleopod 1 (Fig. 8D) protopod subrectangular, distal margin concave; exopod ovoidal, outer margin almost straight, proximal, inner and distal margins rounded; endopod longer than exopod, basal article short, distal article ca. twice longer than basal one. Pleopod 2 (Fig. 8E) exopod ovoidal, twice as wide as long, one seta on inner margin; endopod of two articles, thickset, second article more than three times longer than first, distal portion subquadrangular, distal outer margin with round shaped lobe directed outwards bearing one triangular process on ventral margin. Pleopod 3-5 exopods as in Fig. 8F-H.

Etymology.

Latin. fervens for very hot, boiling hot. The new species name refers to the very hot temperatures of the Brazilian state of Piauí .

Remarks.

Pectenoniscus fervens sp. nov. differs from all other species of the genus in the shape of the male pleopod 2 endopod. Moreover, it differs from P. pankaru sp. nov. in having the antennula bearing six aesthetascs, the dactylar seta stout and in the different shape of the male pleopod 1 and pleopod 3-5 exopods. The new species shows the same number of aesthetascs of the antennula as in P. morrensis and P. santanensis, from which it differs in the antennal flagellum composed of four articles (three in P. morrensis and P. santanensis), male pleopod 1 protopod with the distal margin concave (vs. straight in P. morrensis, almost straight in P. santanensis), male pleopod 4 exopod triangular (vs. subrectangular in P. morrensis, subquadrangualar in P. santanensis), and male pleopod 5 exopod rhomboid and longer than wide (vs. triangular and as long as wide in P. morrensis, subquadrangular in P. santanensis).

The specimens of Pectenoniscus fervens sp. nov. were found only in the aphotic zone (Fig. 2J), in vegetable debris with clay and under rocks, where the humidity was higher than at the cave entrance.