Spelaeogammarus uai, Bastos-Pereira, Rafaela & Ferreira, Rodrigo L., 2017

Bastos-Pereira, Rafaela & Ferreira, Rodrigo L., 2017, Spelaeogammarus uai (Bogidielloidea: Artesiidae): a new troglobitic amphipod from Brazil, Zootaxa 4231 (1) : -

Spelaeogammarus uai sp. nov.

( Figs. 2–5 )

Etymology. Until the present, all species known for the genus Spelaeogammarus were found in the Brazilian state of Bahia. The current work describes the first species recorded for the state of Minas Gerais where “ uai ” is a common interjection used by people who lives in the state meaning doubt, astonishment or surprise.

Material examined. Holotype male, 11.4 mm, July 2014, Lapa D’Água do Zezé cave (15°01'07.45'' S 44°12'10.86'' W) municipality of Itacarambi , state of Minas Gerais, Brazil, ISLA14962 ( Fig. 2 ). Eight paratypes were dissected, four males and four females. Males mean body length: 10.25 mm (± 1.81), mean female body length: 8.64 mm (± 3.7) . January 2015, Lapa D’Água do Zezé cave (15°01'07.45'' S 44°12'10.86'' W) municipality of Itacarambi , state of Minas Gerais, Brazil , ISLA14963, ISLA 14964, ISLA14965, ISLA 14966, ISLA14967, ISLA 14968, ISLA14969. Other six paratypes were kept entire, ISLA 14970, ISLA14971, ISLA 14972, ISLA14973, MNRJ 26136 , MNRJ 26137 . These last were collected in the same locality on the same date.

Diagnosis. Antenna 1 flagellum with 17–20 articles; accessory flagellum 5-articulate. Antenna 2 flagellum with 7–8-articles. Left mandible accessory setal row consisting of 6 curved plumose setae. Maxilla 1 outer lobe apical margin with 7 multi-cuspidate stout setae, palp article 2 with 4 slender apical setae. Maxilliped inner plate apical margin with 2 Y-shaped stout setae and 3 plumose setae, palp article 3, apical margin bearing a row of small, blunt and plumose nodular setae. Gnathopod 1 basis anterior margin with 6 small setae, posterior margin bearing 15 long setae, propodus palm acute, about 2.5 times longer than posterior margin. Gnathopod 2, basis subrectangular, about 3.8 times longer than wide, posterior margin with 18 long slender setae. Pereopod 5 propodus about 8.0 times longer than wide. Pleopods inner ramus with 9 setae. Pleopod 2 peduncle about 4.3 times longer than wide. Uropod 3 outer ramus bearing 16 dorsal bifid setae and 3 apical stout setae. Telson with 1 apical and 3 subapical stout setae.

Description. Body slender. Head without eyes, slightly deeper than long, about as long as pereonites 1 and 2 combined; lateral cephalic lobe rounded, anteroventral corner subquadrate, without setae. Antenna 1, slightly less than half the body length, peduncle slightly longer than flagellum, article 1 0.7 times as long as articles 2 and 3 combined, ratio of peduncular articles 1–3 = 2: 1.5: 1; flagellum with 17–20 articles; accessory flagellum 5- articulate, article 5 reduced, total length of accessory flagellum as long as articles 1 to 5 of flagellum combined. Antenna 2, about 0.9 times the length of antenna 1, peduncle 3 times longer than flagellum, article 2 cone gland rising up to the distal margin of article 3, article 5 0.8 times the length of article 4; flagellum 7 or 8-articulate.

Upper lip rounded and smooth, with sparse setules apically. Lower lip, inner lobe apically rounded with few setules; outer lobe well developed, broadly rounded. Left mandible, molar broad, semi-triturative, subcircular; accessory setal row consisting of 6 curved plumose setae, 3 of them longer and stronger than the others; lacinia mobilis present, well developed, broad and apically 5-cuspidate; incisor multi-cuspidate; palp 3-articulate, article 1 about 1.5 longer than wide, article 2 slightly robust, about 2.8 times longer than wide, longer than article 3, ventral margin bearing 4 slender setae, article 3 tapering distally, with 5 slender setae. Right mandible subequal to left mandible, accessory setal row consisting of 4 curved plumose setae, 2 of them longer and stronger than the others; lacinia mobilis present, multi-cuspidate. Maxilla 1, inner plate apically round, bearing 3 slender setae on apical margin, about 0.7 times the length of outer plate; outer plate subrectangular, bearing 7 multi-cuspidate setae on apical margin; palp 2-articulate, article 2 tapering distally, with 4 slender apical setae. Maxilla 2, short, inner plate slightly wider than outer plate, apical margin bearing a fringe of long setae and 2 plumose setae; outer plate slightly longer than inner plate, apical margin bearing a fringe of slender setae, lateral margin with 2 shorter setae. Maxilliped, inner and outer plates short; inner plate suboval, apical margin with 2 Y-shaped stout setae, 3 plumose setae; outer plate longer than inner, suboval, bearing 9 stout setae apically; palp 4-articulate, article 1 about 1.8 times longer than wide, article 2, the largest, about 2.4 times longer than wide and 1.4 times longer than article 3, apical margin bearing a row of small, blunt and plumose nodular setae, article 4 tapering distally, inner margin setose, claw present distally.

Gnathopod 1, coxa subrectangular; basis stout, about 1.9 times longer than wide, anterior margin with 6 small setae, posterior margin bearing 15 long setae; ischium subtriangular, distoventral corner with 1 slender seta; merus, ventral margin setose; carpus subtriangular, posterodistal corner produced, without comb-scales, posterodistal margin with a fringe of plumose setae; propodus stout, suboval, about 1.5 times longer than basis, palm acute, about 2.5 times longer than posterior margin, covered by a dense fringe of small setae, bearing 8 stout setae; dactylus long, curved, with 5 sets of 1-2-1-3-3 small simple setae dorsally, not reaching the palmar corner.

Gnathopod 2, basis subrectangular, about 3.8 times longer than wide, posterior margin with 18 long slender setae; ischium slightly wider than long, posterior margin with 1 slender setae; merus subrectangular, about 2.9 times longer than wide; carpus subtrapezoidal, about 1.3 times longer than wide, posterior margin setose; propodus suboval, slightly elongate, about 2.0 times longer than wide, anterior and posterior margins setose, palm acute, about 0.7 times shorter than posterior margin, covered by a dense fringe of small setae, bearing 6 stout setae, dactylus long, curved, naked, almost reaching the palmar corner.

Pereopod 3, coxa suboval, about 1.4 times longer than wide, ventral margin with 9 setae; basis suboval, elongate, anterior and posterior margins without setae, posterodistal corner with 1 small seta; merus, about 3.1 times longer than wide, slightly shorter than carpus, anterior margin with 2 stout setae, anterodistal corner with 2 stout setae, posterior margin with 6 setae; carpus elongate, about 5 times longer than wide, slightly longer than merus, anterior margin without setae, posterior margin with 6 sets of 1-2-1-2-1-2 setae; propodus elongate, about 7.2 times longer than wide, slightly shorter than carpus, anterior margin without setae, posterior margin with bearing 8 lateral sets of (1-2-2-1-2-1-1-2) setae; dactylus slightly curved with 1 small plumose setae on dorsal margin, apical nail present. Pereopod 4 subequal in length to pereopod 3. Pereopod 5, coxa bilobate, anterior lobe well developed, about 1.3 times wider than long, with 12 slender setae, posterior lobe small, posterior margin slightly concave, bearing 1 stout seta; basis suboval, about 2.0 times longer than wide, anterior margin bearing 8 stout setae and 3 distal stout setae, anterior margin with 7 marginal stout setae 2 distal stout setae; merus about 3.1 times longer than wide, anterior margin with 4 sets of 1-1-1-2 slender setae, posterior margin with 2 stout setae; carpus slightly elongate, 6.0 times longer than wide, about 1.2 times longer than merus, anterior margin with 6 sets of 1-1-2-2-2-2 stout setae, anterodistal corner with 2 stout setae, posterior margin with 3 sparse slender setae; propodus slightly elongate, about 8.0 times longer than wide, about 1.5 times the carpus length, bearing 8 lateral sets of stout setae (1-1-2-1-2-2-1-2), anterior margin with a dense fringe of small slender setae; dactylus slightly curved, apical nail present. Pereopod 6 slightly shorter than pereopod 5, coxa bilobate, anterior lobe slightly more developed than posterior, posterior margin with 1 stout seta; basis suboval, about 1.9 times longer than wide, anterior margin bearing 8 stout setae, posterior margin with 12 stout setae, merus slightly elongate, about 3.4 times longer than wide, anterior margin bearing 4 stout setae and 2 on the anterodistal corner, posterior margin bearing 2 stout setae and 1 stout setae on posterodistal corner; carpus slightly elongate, 5.6 times longer than wide, about 1.2 times longer than merus, anterior margin with a dense fringe of slender setae and 4 sets of 1-2-2-2 stout setae, anterodistal corner with 3 stout setae, posterior margin with 3 setae, posterodistal corner with 1 stout seta; propodus slightly elongate, about 8.5 times longer than wide, about 0.8X the length of carpus, bearing 15 lateral sets of stout setae (1-1-1-1-2-1-1-2-1-1-2-1-2-1-2), anterior margin with a dense fringe of small slender setae, anterodistal corner with 1 stout seta, posterior margin naked; dactylus slightly curved, apical nail present. Pereopod 7 about 1.3 times the length of pereopod 6, coxa subtriangular, about 0.6 times wider than long, with 1 posterior stout seta; basis suboval, about 1.6 times longer than wide, anterior and posterior margins with several stout setae; ischium slightly stout; merus about 2. 8 times longer than wide, anterior margin with 5 stout setae, anterodistal corner with 3 stout setar, posterior margin 3 sets of 1-2-2 stout setae, posterodistal corner with 2 stout setae; carpus about 5.8 times longer than wide, about 1.4 times longer than merus, anterior margin with 4 sets of 1-1-3-3 setae, anterodistal corner with 5 stout setae, posterior margin with 3 sets of 3-3-3 stout setae, posterodistal corner with 5 stout setae; propodus elongate, about 7.9 times longer than wide, about 1.3 times longer than carpus, anterior and posterior margins densely setose; dactylus slightly curved, apical nail present.

Pleopod 1, peduncle rectangular, about 5.0 times longer than wide, a pair of hook setae present (probably a cuticular structure of unknown nature); inner ramus 1-articulate, bearing 9 plumose slender setae; outer ramus 3- articulate, subequal in length to inner ramus, article 1, inner margin with 6 plumose setae, outer margin with 11 plumose setae, article 2 with 2 plumose setae, article 3, smallest, with 2 apical plumose setae. Pleopod 2, peduncle rectangular, about 4.3 times longer than wide, a pair of hook setae present; inner ramus 1-articulate, bearing 9 plumose slender setae; outer ramus 3-articulate, slightly longer than inner ramus, article 1, inner margin with 7 plumose setae, outer margin with 13 plumose setae, article 2 with 2 plumose seta, article 3, smallest, with 2 apical plumose setae. Pleopod 3 peduncle rectangular, about 3.4 times longer than wide, a pair of hook setae present; inner ramus 1-articulate, bearing 9 plumose slender setae; outer ramus 3-articulate, slightly longer than inner ramus, article 1, inner margin with 6 plumose setae, outer margin with 11 plumose setae, article 2 with 2 plumose seta, article 3, smallest, with 2 apical plumose setae.

Uropod 1, peduncle elongate, about 3.4 times longer than wide, bearing 4 ventral stout setae, 4 dorsal stout setae and 4 lateral stout seta; inner ramus slightly shorter than outer ramus, both lanceolate; inner ramus about 0.8 times the peduncle length, bearing 3 dorsal, and 5 apical setae; outer ramus bearing 5 dorsal and 4 apical setae. Uropod 2, peduncle about 2.5 times longer than wide, bearing 1 dorsal and 2 distolateral stout setae; rami subequal in length, 1.2times longer than peduncle; inner ramus bearing 2 dorsal, 1 ventral and 4 apical stout setae; outer ramus bearing 1 dorsal, 2 ventral, and 5 apical stout setae. Uropod 3 peduncle short, about 1.9 times longer than wide, without setae; rami elongate, lanceolate; outer ramus bearing 6 ventral sets stout setae (3-3-3-3-3-3), 21 dorsal bifid setae and 3 apical stout setae, 2.3 times longer than peduncle; inner ramus subequal in length to outer ramus, bearing 7 dorsal sets of stout setae (1-1-1-2-2-2-2), 3 ventrodistal sets of 2-2-2 stout setae and 3 apical stout setae.

Telson slightly longer than wide, apical margin with shallow U-shaped excavation, bearing in each lobe 1 apical stout seta and 3 subapical stout setae.

Figures

FIGURE 2. Spelaeogammarus uai sp. nov. Holotype male, 10.25 mm, ISLA 14962. Lapa D’Água do Zezé cave, municipality of Itacarambi, state of Minas Gerais, Brazil.

FIGURE 3. Spelaeogammarus uai sp. nov. Paratype male, 9.98 mm, ISLA 14963. Scale bars: 200 µm.

FIGURE 4. Spelaeogammarus uai sp. nov. Paratype male, 9.98 mm, ISLA 14963. Scale bars: 200 µm.

FIGURE 5. Spelaeogammarus uai sp. nov. Paratype male, 9.98 mm, ISLA 14963. Scale bars: 200 µm.