Niambia ghaubensis 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

publication ID	https://dx.doi.org/10.3897/subtbiol.40.72499
persistent identifier	https://treatment.plazi.org/id/DD0EB083-2510-585D-904F-C1B84092278F
treatment provided by	Subterranean Biology by Pensoft
scientific name	Niambia ghaubensis Cardoso, Taiti & Ferreira
status	sp. nov.

Treatment

Niambia ghaubensis Cardoso, Taiti & Ferreira View in CoL sp. nov.

Figs 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8

Material examined.

Holotype. • Male ; Namibia, Tsumed, Ghaub cave, 05 November 2008, leg. R. L. Ferreira (ISLA 78795) . Paratypes. • 1 male (slide), 6 females, same data as holotype ( ISLA 78796).

Description.

Maximum length: male, 4 mm; female, 5 mm. Colorless (Fig. 5A, B View Figure 5 ). Dorsal surface smooth with scattered fan-shaped scale-setae (Figs 5E View Figure 5 , 6A View Figure 6 ); 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. 6B View Figure 6 ; gland pores not visible. Cephalon (Fig. 5C View Figure 5 ) with no suprantennal and frontal lines; eyes absent. Pleon slightly narrower than pereon, pleonites 3-5 epimera with triangular posterior points. Telson (Fig. 6C View Figure 6 ) triangular with straight sides, apex right-angled. Antennula (Figs 5D View Figure 5 , 6D View Figure 6 ) with three articles, second article shortest, distal article with ca. 10 aesthetascs. Antenna (Fig. 6E View Figure 6 ) reaching distal margin of pereonite 3 when extended backward; fifth article of peduncle shorter than flagellum; flagellum with two articles, second article about 3.5 times as long as first. Mandibles (Fig. 6F, G View Figure 6 ) with molar penicil consisting of 6-7 setae arising from common stem; left mandible with 2+1 penicils, right mandible with 1+1 penicils. Maxillula (Fig. 6H View Figure 6 ) outer branch with 4 + 5 (four of them cleft) plus one small tooth between inner and outer teeth; inner branch with two penicils. Maxilla (Fig. 6I View Figure 6 ) with bilobate apex, inner lobe distinctly smaller than outer one. Maxilliped (Fig. 6J View Figure 6 ) basis rectangular; palp basal article with two stout setae, distal article with apical tuft of setae; endite rectangular, medial portion with one long and one small seta, distal margin with 2 teeth. Pereopod 1 (Fig. 7B View Figure 7 ) carpus with transversal grooming brush. Pereopods with inner claw of dactylus smaller than outer one (Fig. 7C View Figure 7 ). Uropod (Fig. 7A View Figure 7 ) protopod reaching distal margin of telson; endopod inserted proximally, shorter than exopod.

Male. Pereopods 1-2 (Fig. 7B View Figure 7 ) merus and carpus with sternal margin covered with long apically trifid setae. Pereopod 7 (Fig. 7C View Figure 7 ) with no distinct sexual modifications. Genital papilla (Fig. 11C View Figure 11 ) with triangular frontal shield. Pleopod 1 (Fig. 7D View Figure 7 ) exopod cordiform, with very short posterior point; endopod longer than exopod, with triangular distal lobe. Pleopod 2 (Fig. 7E View Figure 7 ) exopod triangular, bearing two setae; endopod slightly longer than exopod. Pleopods 3-5 exopods as in Fig. 7F-H View Figure 7 .

Etymology.

The new species is named after Ghaub cave, the type-locality of the species.

Taxonomic remarks.

Niambia ghaubensis sp. nov. differs from N. botswanaensis sp. nov. by the telson with right-angled instead of obtuse apex, male pereopods 1-2 with a brush of setae on carpus and merus sternal margin instead of sparse setae, dactylus of pereopods with a thinner inner claw, and male pleopod 1 exopod cordiform instead of rounded.

Ecological remarks.

The Ghaub cave is the third largest cave in Namibia, with approximate 2.5 km of passages. It consists of an intricate net of labyrinthine conduits with different levels. The lowest level connects to the phreatic level; thus, some ponds are observed inside the cave. The cave is inserted in the dolomites of the Otavi geological group, dating from the upper Precambrian ( Goudie and Viles 2015). The cave has a single entrance (Fig. 8A View Figure 8 ), in which there is currently a gate installed to prevent unauthorized entry. The conduits’ morphologies are somewhat variable since they transect an intricate stratigraphy along the almost 40 m vertical gap within the rock (Fig. 8B, C View Figure 8 ). Although the lower levels of the cave are connected to the phreatic level, most of the cave remains dry. Yet, moist substrates occur in some areas by drip water from speleothems. Organic resources observed are mainly the guano produced by insectivorous bats, where invertebrates are usually concentrated. Specimens of Niambia ghaubensis sp. nov. were only found in the deep sections of the cave, associated with moist substrates (Fig. 8D View Figure 8 ). Curiously, such areas were devoid of other invertebrates, and also of guano. Hence, it seems that this species is highly specialized, avoiding areas richer in organic matter and, thus, other invertebrate species (including predators). Individuals were observed freely walking on the cave floor.

The Ghaub cave is currently used for touristic purposes, receiving visitors regularly. However, apart from the rudimentary stone stairway at the gate entrance in the first conduit, no other man-made structures are present in the cave. The only altered area in the cave due to the tourism is a small chamber at the lower level, which is quite moist with mud. In this chamber, locals used to make mud animals that were left in some parts of the chamber, forming curious sets of mud figures (Fig. 8E View Figure 8 ). Fortunately, the cave sections where N. ghaubensis sp. nov. occurs are difficult to access, which minimizes the threat to this species by visiting tourists. The region’s climate is considered as hot semi-arid (BSh), according to the updated Koppen-Geiger classification ( Beck et al. 2018). According to historical data from 1982 to 2012, the average annual rainfall in the area ranges from 500 to 600 mm, with the wet season occurring from November to March ( Merkel 2019). The cave is located in the "Angolan Mopane Woodlands" ecoregion ( Dinerstein et al. 2017). The surface environment surrounding the cave is protected and located in a reserve that hosts tourists also for photographic safaris. The Otavi mountains are, in general, well preserved, with the land cover dominated by natural forests (Fig. 8F View Figure 8 ).