Hyalella minuana Talhaferro & Bueno, 2021

Talhaferro, Jordan Tuparai, Bueno, Alessandra Angélica De Pádua, Pires, Mateus Marques, Stenert, Cristina, Maltchik, Leonardo & Kotzian, Carla Bender, 2021, Three new species of Hyalella (Crustacea: Amphipoda: Hyalellidae) from the Southern Brazilian Coastal Plain, Zootaxa 4970 (2), pp. 257-292 : 259-269

Hyalella minuana Talhaferro & Bueno , n. sp.

( Figs 3–8 )

Type locality: São José do Norte municipality, Rio Grande do Sul state, Brazil, sampling site P1 (31º 62’ 68.96” S, 51º 42’ 59.12” W) .

Type specimens. Holotype: male, body length = 7.0 mm; head length = 1.0 mm ( MZUSP 41786 ), São José do Norte municipality (31º 62’ 68.96” S, 51º 42’ 59.12” W), September 2015, Pires, M. M. & cols . Allotype: female, body length = 5.2 mm, head length = 0.6 mm ( MZUSP 41787 ), same locality as holotype .

Paratypes: MZUSP 41788 , 10 whole specimens (5 males and 5 females); CCUFLA 440, 10 whole specimens (5 males and 5 females), 3 males and 1 female on slides; CRU0012, 249 whole specimens (31 males, 110 females and 108 juveniles), and 2 males on slides (same collection data of the holotype) ;

Additional specimens. CRU0013, 27 whole individuals (1 male, 9 females and 17 juveniles) and 5 males on slides, São José do Norte municipality, Rio Grande do Sul state, Brazil, sampling site P2 (31º 51’ 10.17” S, 51º 26’ 73.47” W), September 2015, Pires, M. M. & cols .

Diagnosis. Body surface smooth. Eyes ovoid and pigmented. Antenna 1 shorter than antenna 2. Maxilla 1 with palp uniarticulate, not reaching half of the distance between the base of palp and base of the setae of the outer plate. Inner plate of maxilla 2 with two papposerrate setae. Propodus of gnathopod 1 hammer-shaped, longer than wide with nine serrate setae on inner margin. Peduncle of uropod 1 slightly longer than the ramus with seven cuspidate setae on margin, presence of curved seta (male) on inner ramus, followed by three cuspidate setae with decreasing size lined up a row. Peduncle of the uropod 2 slightly longer than the ramus, outer ramus with five cuspidate setae and inner ramus with six cuspidate setae, in both ramus there are is two robust cuspidate setae on apex (one long and one smaller). Peduncle of the uropod 3 and ramus with similar size, peduncle with three cuspidate setae and ramus with six simple setae and one robust cuspidate seta. Sternal gills on pereonites 2 to 7.

Description of male. Mean body length: 7.78 ± 0.37 mm (n=5), mean head length = 0.96 ± 0.04 mm (n=5). Body surface smooth. Eyes ovoid and pigmented. Epimeral plate not acuminated ( Fig. 3A ).

Antenna 1 ( Fig. 3B ): 3.4 mm; peduncle with three articles; first article longer than wide and longer than the third, first article with cuspidate setae on the distal margin; second article with simple setae distributed along the margin; flagellum with 13 articles, all with a group of 2-5 simple setae apically. Aesthetascs observed only in articles 2 and 11.

Antenna 2 ( Fig. 3C ): 5.0 mm, surpassing half of the body length; peduncle longer than head length; flagellum consisting of 15 articles of similar size, with a group of 2-5 simple setae apically.

Basic amphipodan mandible type (in sensu of Watling 1993) with palp absent. Right mandible ( Fig 3D ) incisor process with five teeth and two pappose setae with a group of setules. Left mandible ( Fig. 3E ) incisor process and lacinia mobilis with five teeth; three pappose setae under the lacinia mobilis. In both mandibles, the molar process is cylindrical, large and triturative, with a group of setules on superior margin and presence of long pappose setae on inner margin.

Upper lip ( Fig. 3F ) with rounded borders and the presence of simple setae and setules, ventral margin with many setules.

Lower lip ( Fig. 3G ) bilobed, with distal margins ovoid, presence of simple setae and setules on inner and distal margins, outer margin smooth.

Maxilla 1 ( Fig. 3H ) palp short and unarticulated, thin apically with one simple seta and setules in the borders, length not reaching half of the distance between the base of the palp and base of the setae on outer plate; inner plate slender, almost reaching the half the length of the outer plate with two apex papposerrate setae, inner and outer margin covered by setules; outer plate with nine serrate setae distributed apically.

Maxilla 2 ( Fig. 3I ) inner and outer plate similar in length and wide; inner plate with simple and serrate setae on apex, inner margin with two papposerrate setae (inner seta short and slender, outer seta long and robust); outer plate with long simple and serrate setae on the apex.

Maxilliped ( Fig. 3J ) plates with apex rounded; inner plate with three cuspidate setae in cone-shaped apical and small pappose setae; inner margin with seven pappose setae, outer margin smooth; outer plate slightly longer than inner plate, with inner margin and apex covered by long simple setae and outer margin smooth; palp with four articles, article 1 with simple setae (1-4) on distal inner margin; article 2 longer and wider than article 3, with inner margin covered by long simple setae; distal inner margin of the article 3 covered by long simple setae, distal outer margin with a group of 4-6 serrate setae and simple setae; dactyl smooth, apex with one long and robust serrate setae and four simple setae subapical with half the length.

Gnathopod 1 ( Figs 4A, B ) subchelate; base long with one simple seta on posterior margin; ischium and merus with a group of simple setae on disto-posterior margin; carpus longer than wide and longer than propodus, posterior lobe is long and convex, forming a shell-shaped structure with a margin covered by serrate setae, inner surface with six simple setae, and disto-anterior margin with a cluster of 5-7 serrate setae; propodus longer than wide, width about 1/5 shorter than length, hammer-shaped, inner face with nine serrate setae arranged in two rows and few smaller simple setae, anterior margin with one simple seta, disto-anterior border covered by comb-scales and a cluster of simple setae, disto-posterior border covered by comb-scales and margin with two simple setae; outer face of propodus not observed; palm transverse and covered by simple and smaller cuspidate setae with accessory seta, with three long and slender simple setae, disto-posterior border of the palm with one cuspidate setae with accessory seta, palm length 1/2 shorter than posterior margin of propodus; dactyl claw-like and covered by comb-scales, length not exceeding the margin of the palm, with one small plumose setae in outer margin.

Gnathopod 2 ( Figs 4C, D ) subchelate; base long with five long simple setae on margin; ischium and merus with long simple setae on disto-posterior margin; carpus with distal margin slightly quadrate, posterior lobe of the carpus longer than wide, length between merus and propodus, with a row of serrate setae in the posterior margin; propodus ovate, length about of 1.6 times longer than wide, anterior margin smooth, length about 2.6 times of maximum length of posterior margin, with a cluster of simple setae on border, disto-posterior border with comb-scales and five smaller simple setae, with detail of apex dactyl, presenting two robust cuspidate setae with accessory setae; palm slightly longer than posterior margin of propodus, with inclination transverse and convex, covered by simple and cuspidate setae of medium size; dactyl claw-like and smooth, not exceeding the palm margin in length, with one small plumose setae in outer margin.

Pereopod 3 and 4 ( Figs 5A, B ): coxal plate of the pereopod 4 excavated posteriorly, in both pereopods the base is long with 3-6 setae on posterior margin; anterior margin of merus with two cuspidate setae, posterior margin of merus with 4-7 groups of cuspidate setae distributed on margin; posterior margin of carpus with five groups of cuspidate setae with accessory seta; posterior margin of propodus with seven groups of the cuspidate setae with accessory seta; dactyl with one small simple setae, the length of dactyl not reaching half of length of propodus.

Pereopod 5 to 7 ( Figs 5C–E ): pereopod 5 small than pereopod 6 and 7, coxal plates bilobed, in coxal plate of pereopod 7 the posterior lobe is 1/3 small of the anterior lobe; base is long, with the anterior lobe rounded and margin serrated with setules, posterior margin with 3-4 cuspidate setae with accessory seta; merus, carpus and propodus are similar in length, anterior margin of the merus with 2-4 cuspidate setae, posterior margin of the merus and carpus with three pairs of cuspidate setae with accessory seta; posterior margin of the propodus with four pair of cuspidate setae with accessory seta; dactyl not reaching half of length of propodus.

Pleopods ( Fig. 6A ) similar, peduncle long and smooth; ramus longer than peduncle, with plumose setae densely distributed for the length of the ramus.

Uropod 1 ( Fig. 6B ) peduncle longer than wide, slightly longer than the ramus, with seven cuspidate setae with accessory seta on superior margin; ramus similar in length and wide, outer ramus with five cuspidate setae with accessory setae distributed along the superior margin of the ramus, apex with two cuspidate setae; inner ramus with four cuspidate setae with accessory setae on the outer side of the ramus, inner side with curved seta reaching the apex of the ramus, followed by three smaller setae arranged in a row, apex with two cuspidate setae.

Uropod 2 ( Fig. 6C ) peduncle slightly longer than the ramus, with four cuspidate setae with accessory seta; ramus similar in length and wide, outer ramus with five cuspidate setae with accessory seta; inner ramus with six cuspidate setae with accessory seta; in both, the apex has two cuspidate setae.

Uropod 3 ( Fig. 6D ) shorter than the peduncle of uropod 1; peduncle longer than wide, similar to the length of the ramus with up to three basal small simple setae, apex with four cuspidate setae with accessory seta and one simple setae; ramus slender with six simple setae apically and one cuspidate seta small and robust.

Telson ( Fig. 6E ) longer than wide; apex with rounded borders with two cuspidate setae with accessory seta and three simple setae.

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

Sternal gills tubular present on pereonites 2 to 7.

Description of female. CCUFLA 440, body length: 8.3 mm; head length 1.0 mm. Antenna 1 ( Fig. 7A ): 3.1 mm; peduncle formed by three articles; first article longer than wide and larger than the others article; flagellum composed of 10 articles, with groups of simple setae. Antenna 2 ( Fig. 7B ): 4.2 mm; reaching half the length of the body; peduncle formed by three articles, greater than the length of the head; flagellum with 13 articles, with groups of simple setae.

Gnathopod 1 ( Fig. 7C, D ) subchelate; long base, with one simple seta at the posterior margin, disto-posterior margin with seven long and slender simple setae; ischium with comb-scales on the posterior margin and seven simple long and slender setae on the distal margin; merus with the disto-posterior margin ovoid, with comb-scales and eight long and slender simple setae; carpus longer than wider, posterior margin convex, forming a shell-like structure, covered by serrate setae arranged in a row on the margin, inner surface of the carpus with seven long and slender simple setae, anterior margin smooth, distal margin with serrate setae; propodus longer than wide and widened distally; length about 1.4 times of maximum width, hammer-shaped, anterior margin with three simple setae, disto-anterior and disto-posterior margin covered by comb-scales, disto-anterior margin with a cluster of simple setae, disto-posterior margin with five small simple setae, inner surface with nine serrate setae arranged in two rows; outer face of propodus not observed; straight palm, length about 1/2 smaller than length of posterior margin of propodus, covered by smaller cuspidate setae with accessory seta and simple setae of the medium-sized, and two simple setae long and slender, disto-posterior margin of the palm with one robust cuspidate seta with accessory seta; dactyl claw-like, not exceeding the length of the palm, covered by comb-scales with a small plumose seta on the posterior margin.

Gnathopod 2 ( Fig. 7E, F ) subchelate; long base with three setae on the margin, disto-posterior margin with seven long simple setae; ischium with comb-scales on the posterior and distal margins with eight simple long and slender setae; merus with comb-scales on the posterior margin, distal margin ovoid with a group of long simple setae distributed; carpus longer than wide, posterior margin convex, forming a shell-like structure, with serrate setae arranged in a row on the distal margin, inner surface with four long simple setae, anterior margin with a simple seta, disto-anterior margin with nine long simple setae; propodus rectangular, longer than wide, with length about 1.8 times than of maximum width,, anterior margin with long simple setae, disto-anterior and disto-posterior margin covered by comb-scales, disto-anterior margin with a group of long simple setae, posterior margin with four small simple setae, inner surface with four serrate setae; palm straight and length about 1/2 smaller than length of posterior margin of propodus, with small cuspidate and simple setae, three long and the others of medium-size, disto-posterior margin with one robust cuspidate seta with accessory seta; dactyl claw-like, not exceeding the length of the palm, covered by comb-scales and with small plumose seta on the posterior margin. Presence of foliaceous oostegites on pereonite, with curl-tipped setae on the margin.

Intraspecific variation. The number of setae in the inner ramus of uropod 2 varied in some males, where it presented five cuspidate setae with accessory seta instead of six ( Fig. 8A ). There was also variation in the format and number of setae in the telson, where a quadrangular shape of the telson was observed, with the presence of 5-6 cuspidate setae with accessory seta, without the presence of simple setae ( Fig. 8B ).

Measurements: For males, the mean body length was of 5.64 ± 1.4 mm, while the mean head length was of 0.7 ± 0.16 mm (n=52). The smallest male specimen had 3.1 mm of body length, and 0.5 mm of head length, while the largest male reached 8.2 mm of body length, with head length reaching 1.0 mm. For females, the mean body length was of 5.4 ± 1.5 mm, and the mean head length was of 0.68 ± 0.18 mm (n=130). The body size of the smallest female reached 2.4 mm and the head length, 0.4 mm, while the body size of the largest female measured 11.0 mm and its head length, 1.0 mm.

Etymology. The specific name is a homage to the first inhabitants of the municipality, the Minuanos Indians, who, together with the Carijó and Charrua Indians, previously inhabited the municipality of São José do Norte, the type of locality of species.

Habitat. Freshwater, epigean. Hyalella minuana n. sp. was found in intermittent ponds, one without and the other with physical connection with other water bodies, with a size smaller than the one-hectare showing emergent and floating vegetation.

Distribution. Specimens of Hyalella minuana n. sp. were found in two wetlands along the Rio Grande Sul state coast, distant from each other ca of 21.6 km. Site P1 ( Fig. 1 ) is a temporary pond with a total area of ca 1,908 m ², connected to another water body, depth of ~ 50 cm and tree vegetation. Site P2 ( Fig. 1 ) is similar to Site 1, but is environmentally more heterogeneous, with water depth varying more than 20 cm, and without hydrologic connection with other water bodies, showing a total size-are of ca 4,801 m ². Both sites showed emergent and floating vegetation.

Taxonomic remarks. Hyalella minuana n. sp. shares some similarities with most species of the genus, mainly the presence of curved seta in the inner ramus of the uropod 1, characteristic of many species of the genus. Hyalella minuana n. sp. presents body surface smooth, differing from H. kaingang Araujo & Cardoso, 2013 , H. pleoacuta González, Bond-Buckup & Araujo, 2006 and H. pseudoazteca González & Watling, 2003 that present dorsal flanges in some segments. Hyalella palmeirensis Streck-Marx & Castiglioni, 2020 resembles Hyalella minuana n. sp. due to the number of setae on the peduncle of uropod 3. However, while H. palmeirensis shows one pappose setae on the inner margin of the maxilla 2, Hyalella minuana n. sp. shows two pappose setae. Also, H. palmeirensis exhibits five serrate setae on the inner surface of the propodus of gnathopod 1, while Hyalella minuana n. sp. have nine serrate setae. Hyalella curvispina Shoemaker, 1942 also resembles Hyalella minuana n. sp. for presenting two pappose setae on the inner margin of the maxilla 2 and three cuspidate setae on the peduncle of uropod 3. However, both species show differences concerning the number of setae on the inner surface of gnathopod 1 and in size and type of the setae on telson. Hyalella curvispina has 5–7 setae on inner margin of gnathopod 1 and its telson is wider than long, with three simple setae. In turn, Hyalella minuana n. sp. present nine serrate setae on inner surface on gnathopod 1 and its telson is longer than wide, showing three cuspidate setae and simple setae. Hyalella castroi González, Bond-Buckup & Araujo, 2006 , H. bonariensis Bond-Buckup, Araujo & Santos, 2008 , H. georginae Streck & Castiglioni, 2017 , H. gauchensis Streck & Castiglioni, 2017 and H. pampeana Cavalieri, 1968 , differs from Hyalella minuana n. sp. in the number and disposition of the setae on uropods, form of telson, as well as in number and disposition of the setae on apex.

Two new species of Hyalella were recently described for the state of Santa Catarina, H. catarinensis Reis & Bueno, 2020 and H. rioantensis Penoni & Bueno, 2020 . Hyalella catarinensis differs from Hyalella minuana n. sp. in the number of setae on the inner surface of gnathopod 1 ( H. catarinensis has four pappose setae; Hyalella minuana n. sp. shows nine serrate setae). In addition, H. catarinensis shows five cuspidate setae on the peduncle of uropod 1, while Hyalella minuana n. sp. shows seven cuspidate setae. In the peduncle of uropod 2, H. catarinensis has three cuspidate setae, while Hyalella minuana n. sp. has four cuspidate setae. In turn, H. rioantensis differs from Hyalella minuana n. sp. for not having papposerrate setae on the inner plate of the maxilla 2, and by the absence of serrate setae on the inner surface of the gnathopod 1.

In addition, H. minuana n. sp., H. catarinensis and H. rioantensis present the propodus ovate; the maxilliped presents comb-scales only in H. rioantensis , being absent in H. minuana n. sp. and H. catarinensis , while H. minuana n. sp. present serrate setae on the maxilliped, and H. catarinensis and H. rioantensis present pappose setae; in the three species the coxal plate is excavated posteriorly, being slightly longer than wide in H. minuana n. sp., longer than wide in H. catarinensis , and deeper than wide in H. rioantensis .

Figures

FIGURE 1. Map showing the geographical location of the study area and the sampling sites.

FIGURE 3. Hyalella minuana n. sp., municipality of São José do Norte, Rio Grande do Sul, Brazil (31º 62’ 68.96” S, 51º 42’ 59.12” W). Paratype male, 8.0 mm. Habitus (A); Antenna 1 (B); Antenna 2 (C); Right mandible (D); Left mandible (E); Upper lip (F); Lower lip (G); Maxilla 1 (H); Maxilla 2 (I); Maxilliped (J). Scale bars: 2.0 mm (A); 1.0 mm (B–C); 0.3 mm (D–I); 0.5 mm (J).

FIGURE 4. Hyalella minuana n. sp., municipality of São José do Norte, Rio Grande do Sul, Brazil (31º 62’ 68.96” S, 51º 42’ 59.12” W). Paratype male, 8.0 mm. Gnathopod 1 (A); Detail of the carpus propodus and dactylus (B); Gnathopod 2 (C); Detail of the carpus, propodus and dactylus (D). Scale bars: 0.5 mm.

FIGURE 5. Hyalella minuana n. sp., municipality of São José do Norte, Rio Grande do Sul, Brazil (31º 62’ 68.96” S, 51º 42’ 59.12” W). Paratype male, 8.0 mm. Peraeopod 3 (A); Peraeopod 4 (B); Peraeopod 5 (C); Peraeopod 6 (D); Peraeopod 7 (E). Scale bars: 0.5 mm.

FIGURE 6. Hyalella minuana n. sp., municipality of São José do Norte, Rio Grande do Sul, Brazil (31º 62’ 68.96” S, 51º 42’ 59.12” W). Paratype male, 8.0 mm. Pleopod (A); Uropod 1 (B); Uropod 2 (C); Uropod 3 (D); Telson (E). Scale bars: 0.5 mm (A–C); 0.3 mm (D); 0.2 mm (E).

FIGURE 7. Hyalella minuana n. sp., municipality of São José do Norte, Rio Grande do Sul, Brazil (31º 62’ 68.96” S, 51º 42’ 59.12” W). Paratype female, 8.3 mm. Antenna 1 (A); Antenna 2 (B); Gnathopod 1 (C); Detail of the carpus, propodus and dactylus (D); Gnathopod 2 (E); Detail of the carpus, propodus and dactylus (F). Scale bars: 0.5 mm.

FIGURE 8. Hyalella minuana n. sp., municipality of São José do Norte, Rio Grande do Sul, Brazil (31º 62’ 68.96” S, 51º 42’ 59.12” W). Paratype male. Uropod 2 (A); Telson (B). Scale bars: 0.5 mm.