Hyalella jaboticabensis, Limberger & Castiglioni & Santos, 2024

Limberger, Márcio, Castiglioni, Daniela Da Silva & Santos, Sandro, 2024, Description of one species of freshwater amphipod Hyalella (Crustacea, Peracarida, Hyalellidae) from the northwest region of the state of Rio Grande do Sul, Southern Brazil, Zootaxa 5403 (3), pp. 331-345 : 334-342

Hyalella jaboticabensis n. sp. Castiglioni, Limberger & Santos

Figures 2–7

Type locality. Brazil, state of Rio Grande do Sul, Vila Trentin, municipality of Jaboticaba, small stream ( Varzea river basin) (27°40’21.4”S- 53°17’30.5W) ( Fig. 1A, B ), 502 meters of altitude, October , 05, 2021, Limberger, M. col.: 30 males and 35 females (being three ovigerous females), CLTA 200 .

Type specimens. Holotype male: body length = 6.4 mm, head length = 0.74 mm. Brazil, state of Rio Grande do Sul, municipality of Jaboticaba, state of Rio Grande do Sul (27°40’21.4”S – 53°17’30.5”W), October , 05, 2021. Castiglioni, D.S. and Streck-Marx, M. T. cols., MNRJ 30144 ( Fig. 2A ) . Allotype female: body length = 5.83 mm, head length = 0.69 mm, Brazil, municipality of Jaboticaba, state of Rio Grande do Sul (27°40’21.4”S – 53°17’30.5”W), October , 05, 2021. Limberger, M., col., MNRJ 30145 ( Fig. 2B ) . Paratypes: five males and five females, same place and data as holotype. Limberger, M., col., MNRJ 30146 .

Additional specimens. Site 1— Brazil, state of Rio Grande do Sul, Vila Trentin, municipality of Jaboticaba , small stream (27°40’21.3”S – 53°17’25.4”W) ( Fig. 1A ) ( Varzea river basin), 561 meters of altitude, December , 04, 2014, Castiglioni, D.S. & Streck-Marx, M. T . cols: 18 males, 14 females (being two ovigerous females), CLTA 38 . Site 2— Brazil, state of Rio Grande do Sul, Vila Trentin, municipality of Jaboticaba , small stream (27°40’19.2”S – 53°17’26.0”W) ( Fig. 1A ) ( Varzea river basin), 496 meters of altitude, October 05, 2021, Limberger, M., col: 11 males, 14 females (being three ovigerous females) and three juveniles, CLTA 201 .

Diagnosis. Body surface smooth. Antenna 2 less than half the body length. Inner margin of maxilla 2 with two papposerrate setae (one more strong and long). Gnathopod 1 hammer-shaped, inner face with nine or ten serrate setae and some simple setae (six to eight), and some comb scales on disto-anterior and disto-posterior margins. Gnathopod 2 propodus ovate with small posterior lobe covered by some comb scales, and carpus with posterior lobe with pectinate border. Inner ramus of uropod 1 of males with one short, curved seta. Uropod 3 peduncle slender (rectangular), wider than ramus, with six cuspidate setae with one accessory seta on outer margin, and two or three cuspidate setae and simple setae on outer ramus. Telson as long as wide (square) with six to eight short and long cuspidate setae with one accessory setae. Sternal gills present on segments 2 to 7.

Description of male (paratypes). Mean body length: 5.87 ± 0.50 mm, mean cephalothorax length: 0.69 ± 0.05 mm (n= 5). Body surface smooth. Epimeral plates not acuminated. Head as long as first two thoracic segments, rostrum absent. Eyes small, pigmented, rounded, and sessile, located behind insertion of antenna 1 ( Fig. 3A ).

Antenna 1 ( Fig. 3B ) less than half body length, shorter than antenna 2 but longer than peduncle of antenna 2; flagellum of 11–13 articles, longer than peduncle; seven pairs of aesthetascs occurring distally on flagellum since article 5.

Antenna 2 ( Fig. 3C ) less than half of the body length, peduncle longer than head, flagellum with 15–17 articles and longer than peduncle.

Basic amphipod mandible ( Fig. 3D ) without palp; incisor toothed with four to six teeth present; left lacinia mobilis with five teeth; seta row on left mandible with three or four main pappose setae plus several simple accessory setae; right mandible with two main pappose setae plus accessory seta; molar large, cylindrical, and triturative in both mandibles; accessory pappose seta present in both molars.

Upper-lip ( Fig. 3E ) margin rounded, and distal margin covered by several short setules on ventral and dorsal faces.

Lower-lip ( Fig. 3F ) outer lobes rounded with several setules on ventral and dorsal faces.

Maxilla 1 ( Fig. 3G ) palp short, uniarticulate, longer than wide and with few distal setules; inner plate slender, smaller than outer plate, with two distal strong papposerrate apical setae; outer plate with nine serrate setae.

Maxilla 2 ( Fig. 3H ) inner plate subequal in length and width to outer plate, with two papposerrate setae (one more strong and long) on mid-inner margin and several simple and serrate setae on anterior margin; outer and inner plate with abundant simple setae.

Maxilliped ( Fig. 3I ) inner plates apically rounded, with three cuspidate setae and pappose setae apically and medially; outer plate more slender than inner plate, apically rounded with apical and medial simple setae; palp longer than outer plate, with four articles, with simple setae; dactylus unguiform, shorter than article 3, and with comb scales, distal setae simple and shorter than nail.

Gnathopod 1 ( Fig. 4A ) subchelate; dactylus claw-like, with denticles in comb scales and one plumose seta; propodus length less than two times maximum width, hammer shaped, inner (ventral) face with nine or ten serrate setae and some simple setae (six to eight), several small simple setae on margin, anterodistal margin with some comb scales, clusters of 14 to 15 simple setae (some short) and, five simple setae on superior margin (three short), posterodistal margin with two strong and short cuspidate setae with one accessory seta, comb scales, and five short simple setae; carpus longer than wide, longer and wider than propodus, with strong and wide posterior lobe with pectinate border with one row of several serrate setae and comb scales, inner face with seven to nine serrate setae; basis, ischium and merus with long serrate and simple setae and some denticles in comb scales posterodistally.

Gnathopod 2 ( Fig. 4B ) subchelate; dactylus claw-like, short, not reaching lobe of propodus, with some endal setae and one plumose setae, without comb scales; propodus ovate, length 1,5 maximum width, anterodistal margin without comb scales, with one cluster of simple setae (15 setae), and three or four simple setae distally, posterodistal margin with two strong and short cuspidate setae with accessory setae, straight lobe with comb scales, and nine or ten simple setae; palm sub-equal to posterior margin of propodus, slope oblique, with two row of several cuspidate setae with accessory setae and simple setae; carpus wider than long with posterior lobe elongated produced between propodus and merus, border pectinate with several serrate setae and with some denticles in comb scales; basis, ischium, and merus with long serrate and simple setae on posterior margin, and posterodistal margin with denticles in comb scales.

Pereiopods 3 to 7 ( Fig. 5A to 5E) simple, dactylus, propodus, carpus, merus, ischium and basis with several simple and cuspidate setae with accessory setae on anterior and posterior margins; dactylus less than half the length of the propodus; pereiopod 3 and 4 with similar sizes, but coxal plates excavated posteriorly on pereiopod 4; pereiopod 5 slightly smaller than others; pereiopod 6 and 7 with similar sizes and longer than others pereiopods.

Pleopods ( Fig. 5F ) not modified, and all similar in shape and size; peduncle slender, shorter than rami, with two coupling spines distally; rami with several plumose setae on both margins.

Uropod 1 ( Fig. 6A ) longer than uropod 2; peduncle longer than rami, with eight or nine dorsal cuspidate setae with accessory setae; rami slightly shorter than peduncle, inner ramus with three dorsal cuspidate setae with accessory setae, male with one short-curved seta followed by six cuspidate setae apically (four of them with an accessory seta); outer ramus with five dorsal cuspidate setae with one accessory setae and four cuspidate setae apically (two of them with an accessory seta).

Uropod 2 ( Fig. 6B ) peduncle subequal rami, with five dorsal cuspidate setae with accessory seta; rami subequal; inner ramus with three dorsal cuspidate setae with accessory setae and seven cuspidate setae apically (five of them with accessory seta), outer ramus with four dorsal cuspidate setae with accessory setae and four distal cuspidate setae (two of them with accessory seta).

Uropod 3 ( Fig. 6C ) shorter than others uropods; peduncle slender (rectangular), wider than ramus, peduncle slightly longer than wide, with six long distal cuspidate setae with accessory setae and one or two slightly long simple setae on the other side, and six to eight small simple setae in the middle of the peduncle face; inner ramus absent; outer ramus uniarticulated, sub-equal to peduncle, with nine or ten simple setae and two or three cuspidate setae apically (one more longer).

Telson ( Fig. 6D ) as long as wide, entire, apically squared, with six to eight strong and cuspidate setae of variable length (short and long) with accessory setae distributed on distal margin, and three small setae close to each main setae.

Coxal gills sac-like, present on segments 2 to 6, and sternal gills tubular, present on segments 2 to 7.

Description of female (paratypes). Mean total length: 5.66 ± 0.85 mm; mean cephalothorax length: 0.66 ± 0.09 mm (n= 5). Antenna 1 flagellum of 11 articles. Antenna 2 flagellum of 14 articles. Gnathopod 1 ( Fig. 7B ) similar in size and shape to gnathopod 1 of male; propodus inner face with nine serrate setae, anterodistal margin with little comb scales, posterordistal margin with two short cuspidate setae, comb scales and two simple setae; carpus with large posterior lobe with pectinate border with row of several serrate setae and without comb scales, inner face with five serrate setae; basis, ischium and merus with posterior margin with comb scales. Gnathopod 2 ( Fig. 7A ) differs from that of male in shape and smaller size; propodus rectangular, more elongated than gnathopod 1, with length about two times maximum width, subchelate, palm transverse; propodus inner face with five serrate setae, anterodistal margin without comb scales and posterodistal margin with comb scales, two short cuspidate setae and six simple setae (in three clusters); carpus with large posterior lobe with pectinate border with a row of several serrate setae and without comb scales, inner face with two serrate setae; basis, ischium, and merus with posterior margin with comb scales. Telson similar in shape and types and number of setae to male.

Habitat and ecological conservation. Freshwater, epigean. The specimens of H. jaboticabensis n. sp. were found in small stream (type locality) of approximately 1.5 meters wide and 30 centimeters deep, with tree vegetation on part of the margin and direct access of livestock (cattle). Near the site there are some rural properties with soybean, wheat and corn plantations, alternated according to the inter-harvests. Besides, H. jaboticabensis n. p. was found in another point of this same stream (site 2) and also another stream (site 1) in the same location (Vila Trentin, municipality of Jaboticaba), which contained vegetation on the margin and crops in the surroundings ( Fig. 1A ). Hyalella jaboticabensis n. sp. is possibly endemic and thus are classified as vulnerable (VU) based on IUCN subcategory D2 (ICMBIO, 2013).

Etymology. The species name jaboticabensis ” refers to the location where this new species was found, the municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil.

Taxonomical remarks. Based on the taxonomic keys of Rogers et al. (2020) and Talhaferro et al. (2021b) and the recently descriptions for the Brazilian and Argentinian species of the genus Hyalella ( Streck-Marx & Castiglioni, 2020; Reis et al., 2020; Talhaferro et al., 2021a; Limberger et al., 2021; Penoni et al., 2021; Rangel et al. 2022; Limberger et al., 2022; Isa Miranda & Peralta, 2022), H. jaboticabensis n. sp. does not match to any described for these countries. Among the striking morphological characteristics of H. jaboticabensis n. sp., we can highlight the presence of inner ramus of male uropod 1 with a short curved setae, two or three cuspidate setae on the ramus of uropod 3 and six long cuspidate setae on the peduncle, gnathopod 1 of males with inner face with nine or ten serrate setae and some simple setae (six to eight) and, telson with six to eight short and long cuspidate setae with accessory setae.

Of the other species that occur in Brazil, H. jaboticabensis n. sp. resembles to H. bonariensis Bond-Buckup, Araujo & Santos, 2008 , H. castroi González, Bond-Buckup & Araujo, 2006 , H. curvispina Shoemaker, 1942 , H. gauchensis Streck & Castiglioni, 2017 , H. georginae Streck & Castiglioni, 2017 , H. imbya Rodrigues & Bueno, 2012 , H. kaingang Bueno & Araujo, 2013 , H. luciae Limberger, Santos & Castiglioni, 2022 , H. montenegrinae Bond-Buckup & Araujo, 1998 , H. pampeana Cavalieri, 1968 , H. palmeirensis Streck-Marx & Castiglioni, 2020 , H. pleoacuta González, Bond-Buckup & Araujo, 2006 , and H. pseudoazteca González & Watling, 2003 by having a curved setae on the inner ramus of uropod 1 of the males. Besides, H. jaboticabensis n. sp. have sternal gills on segments 2–7, similar to majority Hyalella species found in Brazil.

Among the species of Hyalella found in Southern Brazil, especially at the state of Rio Grande do Sul, H. jaboticabensis n. sp. has morphological similarities to H. kaingang , especially at the shape of gnathopod 1 and 2 and telson. However, Hyalella jaboticabensis n. sp. has two or three cuspidate setae on the rami of uropod 3, while H. kaikang has only one seta. Furthermore, the curved setae found on the inner rami of male uropod 1 is longer in H. kaigang . However, H. jaboticabensis n. sp. differs from other species found in northwest region of state of Rio Grande do Sul ( H. imbya , H. gauchensis . H. georginae , H. luciae , H. longipropodus and H. palmeirensis ) especially the number of serrate setae on inner face of gnathopod 1, number of cuspidate setae on peduncle and ramus of uropod 3, shape of the telson, and type and number of setae on telson ( Tab. I ). Furthermore, in H. jaboticabensis n. sp. the males have a short and curved setae on uropod 1.

Figures

FIGURE 1. (A) Overview of the type locality and other sites where Hyalella jaboticabensis n. sp. where sampled. (B) Small stream (type locality) of Hyalella jaboticabensis n. sp., municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil.

FIGURE 2. Hyalella jaboticabensis n. sp., municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil. (A) Holotype male, scale bar 0.74 mm. (B) Allotype female, scale bar 0.70 mm.

FIGURE 3. Hyalella jaboticabensis n. sp., municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil. Paratype male. (A) habitus from holotype; (B) antenna 1; (C) antenna 2; (D) mandible; (E) upper-lip; (F) lower-lip; (G) maxilla 1; (H) maxilla 2; (I) maxilliped. Scale bars: 0.2 mm.

FIGURE 4. Hyalella jaboticabensis n. sp., municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil. Paratype male. (A) gnathopod 1; (B) gnathopod 2. Scale bars: 0.2 mm.

FIGURE 5. Hyalella jaboticabensis n. sp., municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil. Paratype male. (A) pereiopod 3; (B) pereiopod 4; (C) pereiopod 5; (D) pereiopod 6; (E) pereiopod 7; (F) pleopod. Scale bars: 0.2 mm.

FIGURE 6. Hyalella jaboticabensis n. sp., municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil. Paratype male. (A) uropod 1; (B) uropod 2; (C) uropod 3; (D) telson. Scale bars: 0.2 mm.

FIGURE 7. Hyalella jaboticabensis n. sp., municipality of Jaboticaba, state of Rio Grande do Sul, Southern Brazil. Paratype female. (A) gnathopod 1; (B) gnathopod 2. Scale bars: 0.2 mm.

Tables

TABLE I. Main morphological difference between Hyalella jaboticabensis n. sp. and other Hyalella species from nearby areas in the northwest region of the state of Rio Grande do Sul, southern Brazil.

Species	Setae in the inner margin of maxilla 2	Number of articles of antenna 1	Number of articles of antenna 2	Sternal gills tubular	Number of setae in the inner face of propodus of gnathopod 1	Curved setae in inner ramus of uropod 1	Number of cuspidate setae on peduncle and ramus of uropod 3, respectively	Telson (shape and number of setae)
Hyalella jaboticabensis n. sp. (1)	Two papposerrate setae, being one of them stronger and longer	11–13	15–17	2–7	9 or 10 serrate setae and 4 to 6 simple setae	Present	6 and 2 or 3	Apically squared, bearing six to eight short and long cuspidate setae with accessory seta
Hyalella imbya Rodrigues & Bueno, 2012 (2)	Two long papposerrate setae	18–23	14–16	3–7	7 serrate setae	Present	1 and 5	Apically rounded with two long simple apical setae
Hyalella gauchensis Streck & Castiglioni, 2017 (3)	Two papposerrate setae, being one of them stronger and longer	11	15	2–7	5 long serrate setae and 9–10 short serrate setae	Present	6 and 1	Apically rounded, as wide as long, with six cuspidate setae apically distributed in three clusters of two setae each
Hyalella georginae Streck & Castiglioni, 2017 (3)	Two robust papposerrate setae	15	16	2–7	9 serrate setae	Present	9 and 1	Apically rounded, as wide as long, with seven apical cuspidate setae with an accessory seta distributed in two clusters (two setae and other side five four setae)
Hyalella palmeirensis Streck-Marx & Castiglioni, 2020 (4)	One strong papposerrate setae	11–12	10–12	3–7	5 serrate setae	Present	3 and 1	As long as wide, with two long simple setae
Hyalella longipropodus Limberger, Graichen & Castiglioni, 2021 (5)	Two papposerrate setae, being one of them stronger and longer	11–12	19–20	2–7	7 serrate setae	Absent	7 and 1	Apically rounded, with two long simple setae and two short cuspidate setae with accessory seta on distal margin
Hyalella luciae Limberger, Santos & Castiglioni, 2022 (6)	Two stronger papposerrate setae, being one of them longer	11–12	14–17	2–7	9 serrate setae and some small simple and triangular setae	Present	11–12 and 1	As long as wide, apically rounded with fifteen cuspidate setae with accessory seta and four simple setae on distal margin

TABLE I. Main morphological difference between Hyalella jaboticabensis n. sp. and other Hyalella species from nearby areas in the northwest region of the state of Rio Grande do Sul, southern Brazil.

Note: References: (1) in this paper; (2) Rodrigues et al. (2012); (3) Streck & Castiglioni (2017); (4) Streck-Marx & Castiglioni (2020); (5) Limberger et al. (2021); (6) Limberger et al. (2022).