Hyalella veredae Cardoso & Bueno

Cardoso, Giovanna Monticelli, Araujo, Paula Beatriz, Bueno, Alessandra Angélica De Pádua & Ferreira, Rodrigo Lopes, 2014, Two new subterranean species of Hyalella Smith, 1874 (Crustacea: Amphipoda: Hyalellidae) from Brazil, Zootaxa 3814 (3), pp. 353-368 : 354-361

publication ID	https://doi.org/ 10.11646/zootaxa.3814.3.3
publication LSID	lsid:zoobank.org:pub:2D820F30-55A5-4B4E-8064-FBB45DD49013
DOI	https://doi.org/10.5281/zenodo.6133284
persistent identifier	https://treatment.plazi.org/id/03DF87D1-FFD6-FF87-FF0C-FBB4DB156C9D
treatment provided by	Plazi
scientific name	Hyalella veredae Cardoso & Bueno
status	sp. nov.

Treatment

Hyalella veredae Cardoso & Bueno View in CoL , sp. n.

( Figs 3 View FIGURE 3 –6)

Type material. Holotype: male, cephalothorax length 0.4 mm, total length 4.7 mm, Brazil, Minas Gerais state, Presidente Olegário municipality, Vereda da Palha Cave (18º15'17"S 46°07'32"W), MZUSP 28420, 13.X.2010, Ferreira, R.L. & Cols. Paratypes: UFRGS 5542 (1 male on slide, 1 male, 1 female), MZUSP 28421 (1 male, 1 female), UFLA 0 261 (1 male on slide, 2 males, 2 females), with the same data as holotype.

Diagnosis. Eyes reduced or absent in some specimens. Antenna 1 and antenna 2 of similar size. Gnathopod 1 and 2 carpus posterior lobe with polygonal pattern and two rows of denticles as comb scales. Gnathopod 1 propodus inner face with five serrate setae, posterior margin with denticles as comb scales; dactylus with denticles as comb scales. Gnathopod 2 propodus hammer-shaped, posterior margin with denticles as comb scales, irregular palm, longer than posterior margin. Uropod 1 inner ramus of male with one curved seta and five apical cuspidate setae with accessory seta.Uropod 3 peduncle with four cuspidate setae with accessory seta, ramus with three to four cuspidate setae.

Description of male. ( Figs 1 View FIGURE 1 D and 3A). Mean body length: 4.3 ± 0.9 mm (n=15); mean cephalothorax length: 0.4 ± 0.09 mm. Body surface smooth, epimeral plates not acuminate. Round and pigmented eyes, with few ommatidia or eyeless (n=45; 4.4% of the sample).

Antenna 1 ( Fig. 3 View FIGURE 3 B) total length reaches fifth pereonite; peduncle length exceeds first pereonite; flagellum with 9 to 11 articles, with two aesthetascs on each article after article 5.

Antenna 2 ( Fig. 3 View FIGURE 3 C) total length reaches sixth pereonite; peduncle surpasses the first pereonite; flagellum with 9 to 11 articles.

Upper lip ( Fig. 3 View FIGURE 3 D) margin rounded, distal border covered by setules on dorsal and ventral faces.

Mandible ( Fig. 3 View FIGURE 3 E) basic amphipodan (in the sense of Watling 1993), but without palp; incisor toothed; left lacinia mobilis with five teeth and setal row with three pappose setae; right mandible with three pappose setae; molar process broad and cylindrical with accessory seta.

Lower lip ( Fig. 3 View FIGURE 3 F) lobes rounded, with setules on dorsal and ventral faces.

Maxilla 1 ( Fig. 3 View FIGURE 3 G) inner plate shorter than outer plate, with two distal papposerrate setae, and several marginal setules. Outer plate with eight to nine serrate setae. Palp short, uniarticulated with few distal setules.

Maxilla 2 ( Fig. 3 View FIGURE 3 H) inner and outer plates of similar sizes, inner plate with two papposerrate setae, five serrulate setae and several simple setae; outer plate with several simple distal setae.

Maxilliped ( Fig. 3 View FIGURE 3 I) inner plate with three cuspidate distal setae and several pappose and simple setae; outer plate with simple setae on the margin; palp with four articles with several simple setae. Dactylus unguiform, smaller than third article, with simple seta and distal nail.

Gnathopod 1 ( Fig. 4 View FIGURE 4 A) subchelate; basis, ischium and merus with simple setae; carpus longer than wider, longer than propodus, lobe posterior margin with polygonal pattern, two rows of denticles as comb scales and a row of serrate setae; propodus length 1.5 times the width (rectangular), hammer-shaped, inner face with five serrate setae, posterior margin with denticles as comb scales; dactylus claw-like with simple setae, one plumose seta and denticles as comb scales ( Fig. 4 View FIGURE 4 B).

Gnathopod 2 ( Fig. 4 View FIGURE 4 C) subchelate; basis, ischium and merus with simple setae on the posterior margin; carpus wider than longer, lobe posterior margin elongated with polygonal pattern, two rows of denticles as comb scales and a row of serrate setae; propodus longer than wider (rectangular), posterior margin with denticles as comb scales, irregular palm, slope oblique strongly inclined, palm 1.1 times longer than posterior margin, margin convex with several simple setae and cuspidate setae with accessory seta (15-18); dactylus claw-like with a plumose seta ( Fig. 4 View FIGURE 4 D).

Pereopods 3 to 7 ( Figs. 4 View FIGURE 4 E and 4F) merus, carpus, propodus posterior margin with cluster of cuspidate setae with accessory seta; dactylus length 1/3 of propodus; propodus dorsal and distal margins with simple setae; pereopod 3 and 4 with similar sizes; pereopod 5 smaller than others; pereopod 6 smaller than pereopod 7, which is about 1.2 times longer than pereopod 3.

Pleopods ( Fig. 5 View FIGURE 5 A) peduncle shorter than rami, with distal coupling spines; both rami with several plumose setae.

Uropod 1 ( Fig. 5 View FIGURE 5 B) peduncle shorter than rami, with five cuspidate setae with accessory seta; inner ramus longer than outer ramus with two cuspidate setae on inner margin, one curved seta and five apical cuspidate setae ( Fig. 5 View FIGURE 5 C); outer ramus with three cuspidate setae with accessory seta on inner margin, and apex with three cuspidate setae and a simple seta (U1 about 5 times the length of U3).

Uropod 2 ( Fig. 5 View FIGURE 5 D) shorter than uropod 1; peduncle shorter than rami, with three cuspidate setae on the margin; inner ramus longer than outer ramus, margin with cuspidate seta with accessory seta, apex with three cuspidate setae and two cuspidate setae with accessory seta; outer ramus with a cuspidate seta with accessory seta on the margin, apex with four cuspidate setae, one with accessory seta.

Uropod 3 ( Fig. 5 View FIGURE 5 E) shorter than uropod 2; peduncle longer than wider with four distal cuspidate setae with accessory seta; ramus uni-articulated, as long as peduncle, with three to four distal cuspidate setae.

Telson ( Fig. 5 View FIGURE 5 F) as wide as long, with two apical cuspidate setae and three plumose setae laterally.

Coxal gills sac-like present on pereonites 2 to 6. Sternal gills tubular present on pereonites 2 to 7.

Female. Mean cephalothorax length: 0.4 ± 0.05 mm, mean body length: 4.5 ± 0.9 mm (n=3). Gnathopod 1 (Fig. 6A) shorter than gnathopod 2, but wider; carpus longer than wider, lobe posterior margin with polygonal pattern and denticles as comb scales on the margin, propodus longer than wider, inner face with four serrate setae. Gnathopod 2 (Fig. 6B) carpus longer than wider, lobe posterior margin with polygonal pattern and denticles as comb scales; propodus rectangular, longer than wider (2 times), inner face with three serrate setae. Uropod 1 (Fig. 6C) peduncle longer than rami, with four cuspidate setae; inner ramus with two cuspidate setae on the margin, apex with five cuspidate setae, three of them with accessory seta; outer ramus with three cuspidate setae on the margin and four distal setae, one of them with accessory seta.

Etymology. The specific epithet veredae refers to the location where the species was found.

Habitat and ecological considerations. The species was found in a freshwater underground stream, in Vereda da Palha Cave, located in the municipal district of Presidente Olegário, near Varjão de Minas city ( Fig. 1 View FIGURE 1 A). The cave is situated in the karst area belonging to the Bambui group, which is extended through the states of Minas Gerais, Goiás, Tocantins and Bahia. The known cave extension corresponds to 1,300 meters, with at least three levels. The lower level is characterized by the presence of a drainage formed by a stream that descends in one of the cave entrances ( Fig. 1 View FIGURE 1 B). No individual was observed in this drainage. Specimens were only found at the second level, which has a succession of travertines ( Fig. 1 View FIGURE 1 C) filled by percolating water probably from epikarst compartments, especially in dry seasons. The main resource observed in these pools consisted of organic matter. In the first sampling (13.X.2010), dozens of individuals were observed swimming on small branches, in a very deep puddle. The water was crystal clear, allowing to observe the bottom and of the specimens. On the same visit, several couples were found in pre-copulatory behavior. On a subsequent visit to the cave (31.I.2011), only one specimen was found. On the occasion, the water from the travertines was quite turbid, indicating that the habitat changes over the year, not only receiving waters from the epikarst compartments. The absence of individuals in this occasion might indicate that the organisms are capable of migrating to other underground compartments, thus avoiding turbid waters.

Remarks. Hyalella veredae represents the first troglobitic species described for the state of Minas Gerais, south-eastern Brazil. H. veredae resembles H. spelaea due to the presence of reduced eyes, while in H. caeca , H. imbya , H. anophthalma and H. muerta the eyes are absent. However, a small part of the population (4.4%) did not present eyes. Culver et al. (1995) described a similar process in cave populations of Gammarus minus Say, 1818 that had different degrees of eyes reduction and different sizes of the antennae. These authors suggest that intraspecific variation may be consequence of time and degree of isolation of each population in underground environments. In addition to the eyes, H. veredae shows different antenna sizes, in which antenna 1 and 2 are subequal in length, The shape of male gnathopod 2 of H. veredae is similar to H. spelaea , H. anophthalma and H. muerta , showing irregular palm, differing from H. caeca and H. imbya , both having a smooth palm. The palm inclination of male gnathopod 2 of H. veredae is similar to H. imbya , both showing palm strongly inclined. The presence of one curved seta in uropod 1 inner ramus is similar to H. imbya . Moreover, it was observed that the number of serrate setae on propodus gnathopod and on uropod 3 is different in H. veredae in comparison to other troglobitic species.