Niambia namibiaensis Cardoso, Taiti & Ferreira, 2021

Cardoso 1, Giovanna Monticelli, Preez 2, Gerhard Du, Taiti 3,4, Stefano & Ferreira 1,5, Rodrigo L., 2021, New troglobitic species of Niambia from Botswana and Namibia (Crustacea, Isopoda, Oniscidea), Subterranean Biology 40, pp. 91-108 : 91

Niambia namibiaensis Cardoso, Taiti & Ferreira sp. nov.

Figs 9 , 10 , 11

Material examined.

Holotype. • Male ; Namibia, Otavi, Märchen cave, 07 November 2008, leg. R. L. Ferreira (ISLA 78797) . Paratypes. • 1 male (slide), 2 females, same data as holotype ( ISLA 78798).

Description.

Maximum length: male, 6 mm. Colorless (Fig. 9A, B ). Dorsal surface smooth with fan-shaped scale-setae (Fig. 10C ); one line of noduli laterales per side on pereonites, at certain distance from lateral margin, b/c and d/c co-ordinates as in Fig. 10A ; some gland pores on pereonites 1 to 7 (Fig. 10C ). Cephalon (Figs 9B , 10B ) with no suprantennal line; eyes reduced to small dot of pigment (Fig. 9B ), absent in some specimens. Pleon slightly narrower than pereon, pleonites 3-5 epimera with triangular posterior points. Telson (Fig. 10D ) triangular with slightly concave sides and rounded apex. Antennula (Fig. 10E ) with three articles, second article shortest, distal article with ca. seven aesthetascs. Antenna (Fig. 10F ) reaching pereonite 2 when extended backward; fifth article of peduncle as long as flagellum; flagellum with two articles, second article about 3 times as long as first. Mandibles (Fig. 10G, H ) with molar penicil consisting of several setae arising from common stem; left mandible with 2+1 penicils, right mandible with 1+1 penicils. Maxillula (Fig. 10I ) outer branch with 4 + 5 teeth (two of them cleft); inner branch with two penicils. Maxilla (Fig. 10J ) with bilobate apex, inner lobe distinctly smaller than outer lobe. Maxilliped (Fig. 10K ) basis rectangular; palp basal article with two stout setae, distal article with apical tuft of setae; endite rectangular, apex with one long seta. Pereopod 1 (Fig. 11A ) carpus with longitudinal grooming brush, inner claw of dactylus thin and shorter than outer one. Uropod (Fig. 10D ) protopod surpassing distal margin of telson, lateral margin grooved with gland pores; endopod inserted slightly proximally, shorter than exopod.

Male. Pereopods 1-4 (Fig. 11A ) merus and carpus with sternal margin covered with long apically trifid setae. Pereopod 7 (Fig. 11B ) without distinct sexual modifications. Genital papilla as in Fig. 11C . Pleopod 1 (Fig. 11D ) exopod triangular with broadly rounded apex; endopod longer than exopod, distal portion tapering. Pleopod 2 (Fig. 11E ) exopod triangular, outer margin slightly concave with four setae on distal part; endopod longer than exopod. Pleopod 3-5 exopods (Fig. 11F-H ) triangular, outer margins with 6-7 setae.

Etymology.

The new species is named after Namibia, where the specimens were collected.

Taxonomic remarks.

Niambia namibiaensis sp. nov. is easily distinguishable from N. botswanaensis sp. nov. and N. ghaubensis sp. nov. in having some gland pores on the lateral margins of the pereonites, a rounded apex of telson, a brush of trifid setae on the male pereopods 1-4 merus and carpus, and a different shape of the male pleopod 1. It also differs from N. botswanaensis sp. nov. in having the dactylus of pereopods with a thinner inner claw.

Ecological remarks.

The Märchen cave and the Ghaub cave are both located in the Otavi Mountains, about 56 km apart. The Märchen cave presents a 12 m vertical shaft at the entrance with the maximum cave depth being 60 m. Farmers installed metal ladders to facilitate access to the cave (Fig. 12A-C ). Specimens of N. namibiaensis sp. nov. were only found in one of the deepest portions of the cave, under rocks on the floor. This was also the only area with noticeable moisture content (Fig. 12D ). Since the visit to the cave occurred in the dry season, most of the cave’s substrates were extremely dry. In the humid part of the cave, where the isopods were found, other invertebrates were also observed, including potential predators such as the troglophilic Bothriuridae scorpion Lisposoma josehermana Lamoral, 1979 and spiders. The cave was not visited for research purposes during the rainy season and therefore it is not possible to determine if the distribution of this species within the cave is subject to seasonality. However, they may likely present a wider distribution during the wet periods since there are many signs of water drips in the cave. Although other caves were also sampled in the same outcrop, no specimens of N. namibiaensis sp. nov. were found. The external environment is well preserved (Fig. 12D ) and even with the facilities to access the cave, there are no signs of human impact inside it. This species is not currently considered threatened.

Figures

Figure 9. Niambia namibiaensis sp. nov. Male paratype A habitus, dorsal view B habitus, lateral view. Scale bars: 1 mm.

Figure 10. Niambia namibiaensis sp. nov. Male paratype A co-ordinates of noduli laterales B cephalon, frontal view C pereonite 1, dorsal view D pereonite 5, telson and right uropod, dorsal view E antennula F antenna G left mandible H right mandible I maxillula J maxilla K maxilliped.

Figure 11. Niambia namibiaensis sp. nov. Male paratype A pereopod 1 B pereopod 7 C genital papilla D pleopod 1 E pleopod 2 F pleopod 3 exopod G pleopod 4 exopod H pleopod 5 exopod.

Figure 12. Niambia namibiaensis sp. nov. A Maerchen cave's entrance from outside B cave's entrance from inside C cave map where the specimens were collected D specimen of Niambia namibiaensis sp. nov. E external environment surrounding the cave.