Hyalella lagoana 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 : 270-279

Hyalella lagoana Talhaferro & Bueno , n. sp.

( Figs 9–14 )

Type locality. Osório municipality, Rio Grande do Sul state, Brazil, sampling site P3 (30º 02’ 44.8” S, 50º 40’ 36.6” W) .

Type specimens. Holotype: male, body length = 7.0 mm; head length = 0.8 mm ( MZUSP 41789 ), Osório municipality (30º 02’ 44.8” S, 50º 40’ 36.06” W), October 2015, Pires, M. M. & cols . Allotype: female, body length = 0.7 mm, head length = 5.4 mm ( MZUSP 41790 ), same locality as holotype .

Paratypes: MZUSP 41791 , 10 whole specimens (5 males and 5 females); CCUFLA 441, 10 whole specimens (5 males and 5 females), 3 males and 1 female on slides; CRU0014, 145 whole specimens (24 males, 72 females and 49 juveniles) and 2 males on slides (same collection data of the holotype) .

Additional specimens. CRU0015, 4 whole specimens (2 female and 2 juvenile) and 4 males on slides, Garopaba municipality, Santa Catarina state, Brazil, sampling site P8 (28º 03’ 96.12” S, 48º 61’ 31.21” W), October 2015, Pires, M. M. & cols .

Diagnosis. Body surface smooth. Eyes ovoid, large and pigmented. Antenna 1 approximately 1/4 smaller than antenna 2. Palp of the maxilla 1 uniarticulate and oval with apex covered by setules. Plates of maxilla 2 similar in length and width, inner plate with two papposerrate setae in the inner margin. Propodus of gnathopod 1 hammershaped, longer than wide, with four serrate setae on the inner surface. Peduncle of the uropod 1 with seven cuspidate setae on the margin, inner side of the inner ramus with four cuspidate setae, with curved setae reaching the apex of the ramus (male). Uropod 2 longer than the peduncle of uropod 1, peduncle with five cuspidate setae, inner ramus with seven cuspidate setae and outer ramus with six cuspidate setae. Sternal gills on pereonites 2 to 7.

Description of male. Mean of body length: 6.74 ± 0.43 mm (n=5), mean of head length: 0.78 ± 0.07 mm (n=5). Body surface smooth. Eyes ovoid and pigmented. Epimeral plate not acuminated ( Fig. 9A ).

Antenna 1 ( Fig. 9B ): 3.0 mm; peduncle with three articles; first article longer than wide and with robust cuspidate setae on the distal margin; flagellum with 13 articles, each article presents a group of simple setae. Aesthetascs were not observed.

Antenna 2 ( Fig. 9C ): 4.0 mm; peduncle longer than head length; flagellum with 14-15 articles presenting groups of simple setae.

Basic amphipodan mandible type (in sensu of Watling 1993) with palp absent. Right mandible ( Fig. 9D ) incisor process with five teeth, and two pappose setae. Left mandible ( Fig. 9E ) incisor process with five teeth; lacinia mobilis with four teeth; three pappose setae and setules below the lacinia. In both mandibles, the molar process is cylindrical, large, and triturative, with single long pappose seta on the inner margin, superior margin of the molar process with setules.

Upper lip ( Fig. 9F ) showing outer borders ovoid, with simple setae on the borders, covered by several setules.

Lower lip ( Fig. 9G ) bilobed, with simple setae and several setules on the inner and ventral margins, outer margins smooth.

Maxilla 1 ( Fig. 9H ) palp uniarticulate, margins covered by setules, apex ovoid with a single apical seta, length not reaching half the distance between the palp base and the base of the setae on the apex of the outer plate; outer plate with nine serrate setae at the apex; inner plate slender, reaching half the length of the outer plate, margins covered by setules, and apex with two papposerrate setae of equal size.

Maxilla 2 ( Fig. 9I ) plates similar in length and width; inner plate longer than wide, apex covered with serrate setae and few simple setae, inner margin with two papposerrate setae, inner seta short and slender, outer seta long and robust; outer plate longer than wide, apex covered by long serrate setae and a few smaller simple setae.

Maxilliped ( Fig. 9J ) inner plate 1/3 smaller than the outer plate, inner margin with six pappose setae, apex rounded with three cuspidate setae in cone-shaped, and smaller pappose setae, outer margin smooth; outer plate reaching half the length of the article 2, inner margin covered by simple setae, outer margin smooth; palp with four articles, articles 1 and 2 with several simple setae on inner margin; inner margin of the article 3 covered by long and slender simple setae, outer distal margin with a group of simple and serrate setae; article 2 and 3 with many setules; dactyl longer than wide, with sub-apical simple setae and apex with a single long serrate setae.

Gnathopod 1 ( Figs 10A, B ) subchelate; long base, with one simple seta on the posterior margin, distal margin with a group of simple setae; ischium with comb-scales and simple setae on the posterior margin; merus similar in length to the ischium, longer than wide, distal margin ovoid with six simple setae; carpus longer than wide, distoanterior margin with a group of serrate setae, inner surface with six simple setae, posterior lobe elongated, forming a shell-shaped structure with a margin covered by serrate setae; propodus longer than wide, length about 1.6 times of maximum width, hammer-shaped, inner face with four serrate setae and a few smaller simple setae, disto-anterior margin with comb-scales and one simple seta, disto-posterior margin with comb-scales and cup for dactyl; outer face of propodus not observed; palm transverse and slightly convex, length about 1/3 smaller than posterior margin length of propodus, covered by simple and cuspidate setae with accessory seta and two long and slender simple setae, distal margin of the palm with two robust cuspidate setae with accessory seta; dactyl claw-like, covered by comb-scales and congruent of the palm length, outer margin with comb-scales and one small plumose seta.

Gnathopod 2 ( Figs 10C, D ) subchelate; showing a long base, with two simple setae on the posterior margin; disto-posterior margin with groups of long and slender simple setae; ischium as long than wide, with group of simple setae on the disto-posterior margin; merus slightly longer than wide, posterior margin ovoid with long and slender simple setae; carpus as long than wide, disto-anterior margin with serrate setae, posterior lobe convex, shell-like shape, covered with serrate setae; propodus ovate, long than wide, length about 1.2 times of maximum width, distoanterior margin with a group of long simple seta, disto-posterior margin covered by comb-scales, posterior margin with one simple seta of intermediate size, inner face with a few simple and smaller setae; palm slightly convex, longer than posterior margin of the propodus (1.2 times), covered by simple and cuspidate setae with accessory seta; disto-posterior margin with two robust cuspidate setae with accessory seta; dactyl claw-like, smooth and congruent of the palm length, with small plumose setae on the outer margin.

Pereopods 3 and 4 ( Figs 11A, B ) similar in size; the coxal plate of the pereopod 4 excavated posteriorly; the base with 4-5 simple setae on the posterior margin in the pereopod 3; in both pereopods, merus longer than carpus with 4-6 groups of simple setae on the posterior margin; carpus with five cuspidate setae on the posterior margin with simple setae; propodus similar to the carpus in length, with seven cuspidate setae on the posterior margin with simple setae; dactyl not reaching half the length of the propodus, with simple seta subapical.

Pereopods 5 to 7 ( Figs 11C–E ): coxal plate bilobed; pereopod 7 with the posterior lobe 1/3 the size of the anterior lobe; pereopod 5 smaller than 6 and 7; pereopods 6 and 7 similar in size; base with anterior margin ovoid, posterior margin with cuspidate setae; merus with cuspidate setae on the anterior and posterior margins; carpus and propodus with pairs of cuspidate setae on the posterior margin; dactyl not reaching half the length of the propodus, with simple seta subapical.

Pleopods ( Fig. 12A ) similar, peduncle longer than wide, approximately 1/2 the length of the ramus; ramus with plumose setae distributed densely over the entire length.

Uropod 1 ( Fig. 12B ) peduncle larger than the ramus and longer than wide, with seven cuspidate setae with accessory setae; ramus similar in length and width; outer ramus with six cuspidate setae with accessory setae, apex with two cuspidate setae; inner ramus with four cuspidate setae with accessory setae on the outer side of the ramus, curved setae on the inner side of the ramus reaching the apex, followed by three cuspidate setae arranged in a row, with decreasing size, apex with two robust cuspidate setae.

Uropod 2 ( Fig. 12C ) larger than the peduncle of uropod 1; peduncle slightly smaller than the ramus, longer than wide, with five cuspidate setae with accessory seta; ramus similar in length and width; outer ramus with six cuspidate setae with accessory seta, apex with two cuspidate setae; inner ramus with seven cuspidate setae with accessory seta, apex with two robust cuspidate setae.

Uropod 3 ( Fig. 12D ) smaller than the peduncle of uropod 1; peduncle with five cuspidate setae with accessory seta and a simple seta; peduncle slightly longer than the ramus, with six long and slender simple setae and small robust cuspidate seta.

Telson ( Fig. 12E ) as longer than wide, apex rounded, with six cuspidate setae with accessory seta and two simple setae at the apex.

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

Sternal gills tubular present on pereonites 2 to 7.

Description of the female. CCUFLA 441, body length: 6.0 mm, head length 0.8 mm. Antenna 1 ( Fig. 13A ): 2.0 mm, smaller than antenna 2; peduncle formed by three articles; first article longer than wide with three long and robust simple setae on the margin, distal border with cuspidate seta; first at the second article wider than the third, and similar in length; third article smaller than the two others, in wide and length; flagellum with 9 articles, all with a group of simple setae. Antenna 2 ( Fig. 13B ): 2.7 mm; peduncle formed by three articles and longer than the length of the head; first article wider than the others, with half the length of the other two articles; second article wider than the third, with similar length; flagellum with 12 articles, all with a group of simple setae.

Gnathopod 1 ( Figs 13C, D ) subchelate; base with long and slender simple setae on the disto-posterior margin; ischium slightly longer than wide, with a group of long and slender simple setae on the disto-posterior margin; merus similar in length and width, disto-posterior margin rounded, with long simple setae; carpus longer than wide, posterior margin smooth, disto-anterior border with a group of long and slender simple setae, posterior margin convex, forming a shell-like structure and covered by serrate setae, inner margin with five simple setae arranged in a row; propodus longer than wide, length about 1.4 times of maximum width, hammer-shaped; anterior margin with two simple setae; disto-anterior and disto-posterior border covered by comb-scales, inner margin with six serrate setae arranged in one row; outer face of propodus not observed; palm slightly convex, length about 1/3 smaller than posterior margin length of propodus, covered by simple setae of intermediary-size and small cuspidate setae, the disto-posterior border with a one small and robust cuspidate seta with accessory seta; dactyl claw-like, not exceeding the length of the palm, covered by comb-scales and with four setules distributed along the inner margin, outer margin with a one simple seta.

Gnathopod 2 ( Fig. 13E, F ) subchelate; long base with a long central simple seta in the posterior margin and a group of simple setae on the disto-posterior margin; ischium slightly longer than wide with comb-scales and long simple setae on the disto-posterior margin; merus longer than wide, the disto-posterior margin rounded with combscales and a group of long simple setae; carpus longer than wide, less than 2 times the length of width, anterior margin smooth, the distal border with a group of simple setae, posterior margin convex, forming a shell-like structure covered by serrate setae, inner margin with two long simple setae; propodus rectangular shape, longer than wide, length about 1.8 times of maximum width, anterior margin with a simple seta and comb-scales, posterior margin with four simple setae and comb-scales from the central region to the distal border, inner surface with three serrate setae arranged in one row; palm slightly convex, length about 2.3 times smaller than maximum posterior margin length of propodus, covered by simple setae, the central region with two long and slender simple setae, the distoposterior border with two small and robust cuspidate setae with accessory seta; dactyl not exceeding the length of the palm, claw-like, covered by comb-scales and with four setules distributed along the inner margin, outer margin with a simple setae. Presence of foliaceous oostegites on pereonite, with curl-tipped setae on the margin.

Intraspecific variation. There was variation in some individuals in the number of bristles in the peduncle and branches of the uropod 3. The peduncle showed three instead of five cuspidate setae with accessory seta, the ramus showed the number of similar subapical setae, however, the number of distal setae differed in both rami, showing only two setae in both ( Fig. 14A ). The telson differed in some individuals that presented a different apex shape, with the rounder and less wide margins, in addition to having some tiny and robust cuspidate setae and the absence of simple setae ( Fig 14B ).

Measurements. For males, the mean body length was of 6.15 ± 0.9 mm, while the mean head length was of 0.71 ± 0.13 mm (n=43). The smallest male specimen had 3.1 mm of body length, and 0.5 mm of head length, while the largest male reached 90 mm of body length, with head length reaching 0.9 mm. For females, the mean body length was of 5.1 ± 1.0 mm, and the mean head length was of 0.63 ± 0.14 mm (n=85). The body size of the smallest female reached 3.1 mm and the head length, 0.4 mm, while the body size of the largest female measured 8.2 mm and its head length, 1.0 mm.

Etymology. The specific name, lagoana, refers to large numbers of ponds found in Osório municipality (23 ponds to all), also known as “Cidade das lagoas”, type locality of species.

Habitat. Freshwater, epigean. Hyalella lagoana n. sp. was found in intermittent ponds, the hydrological connection with other water bodies is present in a single pond, in both ponds, the size-area is smaller than the one-hectare, and feature emergent and floating vegetation.

Distribution. Hyalella lagoana n. sp. were registered in two sampling sites. Site P3 is an intermittent pond located in the Rio Grande do Sul ( Fig. 1 ), showing a total size-area of 1,387 m ², depth uniform, and inferior to 50 cm. This site is isolated from other water bodies and shows no arboreous vegetation near their banks. Sampling site P8 is located in Santa Catarina ( Fig. 1 ), shows a total area of ca. 3,500 m ², and is environmentally similar to site 3. However, its depth is not uniform along its area varying more than 20 cm, but not surpassing 50 cm. Its hydroperiod is permanent, and it is connected to other water bodies. Both, sites P3 and P8 contain emergent and floating vegetation in the margins.

Taxonomic remarks. Hyalella lagoana n. sp. shares important characteristics with other species, such as presence of curved seta on the inner ramus of uropod 1, that also occurs in H. georginae , H. gauchensis , H. montenegrinae Bond-Buckup & Araujo, 1998 , H. curvispina , H. castroi , H. kaingang , H. pleoacuta , H. carstica Bastos-Pereira & Bueno, 2012 , H. xakriaba Bueno & Araujo, 2013 , H. palmeirensis and H. bonariensis . However, Hyalella lagoana n. sp. differs from H. kaingang , H. pleoacuta and H. pseudoazteca , due to the absence of flanges in pereon and in pleonites. Hyalella lagoana n. sp. is similar to H. montenegrinae and H. pampeana due to the number of setae on the peduncle of uropod 3 and to the presence of two papposerrate setae in the inner margin of the inner plate of the maxilla 2. Hyalella lagoana n. sp. differs from H. montenegrinae and H. pampeana in characteristics related to the number of flagellum on the antennae 1 and 2, number of serrate on the inner surface of gnathopod 1 and in the form and number of setae on telson. Hyalella lagoana n. sp. also differs from H. georginae , H. gauchensis , H. curvispina , H. castroi , H. carstica , H. xakriaba , H. palmeirensis and H. bonariensis by the number of flagellum on the antennae 1 and 2, of serrate setae on the inner surface of the propodus of gnathopod 1, as well as by the number and disposition of setae on uropods, form of telson, and by the type and disposition of setae on the apex of the telson.

Hyalella lagoana n. sp. also shares similarities with two species recently described for the Santa Catarina state ( Reis et al. 2020). However, it differs from H. catarinensis by the number of papposerrate setae on the inner plate of the maxilla 2 ( H. catarinensis with one papposerrate seta on inner plate), and by the form and number of setae cuspidate on the telson ( H. catarinensis with telson longer than wide, and with three cuspidate setae apical). Hyalella rioantensis differs from Hyalella lagoana n. sp. for presenting four cuspidate setae on the apex of telson, four to six cuspidate setae on the peduncle of uropod 1, and three or four cuspidate setae on the peduncle of uropod 2.

In addition, Hyalella lagoana n. sp. differs from Hyalella minuana n. sp. in number of the teeth on lacinia mobilis of the left mandible ( Hyalella lagoana n. sp. with four teeth, Hyalella minuana n. sp. with five teeth); the number of pappose setae on the inner plate of the maxilliped ( Hyalella lagoana n. sp. with six pappose setae; Hyalella minuana n. sp. with seven pappose setae); and the number of serrate setae on the inner surface of gnathopod 1 ( Hyalella lagoana n. sp. with four serrate setae; Hyalella minuana n. sp. with nine serrate setae).

Figures

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

FIGURE 9. Hyalella lagoana n. sp., municipality of Osório, Rio Grande do Sul, Brazil (30º 02’ 44.8” S, 50º 40’ 36.6” W). Paratype male, 7.0 mm. Habitus (A); Antenna (B); Antenna 2 (C); Mandible right (D); Mandible left (E); Upper lip (F); Lower lip (G); Maxilla 1 (H); Maxilla 2 (I); Maxilliped (J). Scale bars: 2.0 mm (A); 0.5 mm (B–C); 0.3 mm (D–I); 0.5 mm (J).

FIGURE 10. Hyalella lagoana n. sp., municipality of Osório, Rio Grande do Sul, Brazil (30º 02’ 44.8” S, 50º 40’ 36.6” W). Paratype male, 7.0 mm. Gnathopod 1 (A); Detail of the carpus propodus and dactylus of the gnathopod 1 (B); Gnathopod 2 (C); Detail of the carpus, propodus and dactylus of the gnathopod 2 (D). Scale bars: 0.5 mm.

FIGURE 11. Hyalella lagoana n. sp., municipality of Osório, Rio Grande do Sul, Brazil (30º 02’ 44.8” S, 50º 40’ 36.6” W). Paratype male, 7.0 mm. Peraeopod 3 (A); Peraeopod 4 (B); Peraeopod 5 (C); Peraeopod 6 (D); Peraeopod 7 (E). Scale bars: 0.5 mm.

FIGURE 12. Hyalella lagoana n. sp., municipality of Osório, Rio Grande do Sul, Brazil (30º 02’ 44.8” S, 50º 40’ 36.6” W). Paratype male, 7.0 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 13. Hyalella lagoana n. sp., municipality of Osório, Rio Grande do Sul, Brazil (30º 02’ 44.8” S, 50º 40’ 36.6” W). Paratype female, 6.0 mm. Antenna 1 (A); Antenna 2 (B); Gnathopod 1 (C); Detail of the carpus, propodus and dactylus of the gnathopod 1 (D); Gnathopod 2 (E); Detail of the carpus, propodus and dactylus of the gnathopod 2 (F). Scale bars: 0.5 mm.

FIGURE 14. Hyalella lagoana n. sp., municipality of Osório, Rio Grande do Sul, Brazil (30º 02’ 44.8” S, 50º 40’ 36.6” W). Paratype male. Uropod 2 (A); Telson (B). Scale bars: 0.5 mm.