Hyalella inca Isa-Miranda, Peralta, González & Nieto, 2025, sp.n.

Hyalella inca sp.n. Figs 8–13. Hyalella aff. puna — Hankel et al., 2023 MATERIAL EXAMINED. Holotype. Argentina: ♂, Catamarca Province, Laguna Antofagasta, – 26.1058° S – 67.42058° W, alt. 3338 m a.s.l, 13.XII.2015, J. Rodríguez leg., (FML-CRUST 01335), 9.8 mm. Paratypes: 1 ♀ measuring 7.35 mm, 2 ♂♂ and 1 ♀ (FML-CRUST 01336); 4 ♂♂ and 2 ♀♀ (IBN-EcoPP-23C); same data as holotype. Additional material: Argentina: 5 ♂♂ and 1 ♀, Salta Province, Aguas Calientes, – 24.39164° S – 66.56256° W, 3795 m a.s.l., 3.II.2014, 3 ♂♂ and 2 ♀♀, Pastos Grandes, – 24.42852° S – 66.67161° W, 4048 m a.s.l, 3.II.2014, 4 ♂ ♂ and 2 ♀♀, Catamarca Province, Laguna Antofagasta, – 26.10413889° S – 67.4185° W, 3331 m a.s.l, 14.XII.2015. J. Rodríguez leg. DIAGNOSIS. Body smooth. Palp of maxilla I asymmetrical, with right branch bearing two setae on tip vs. only one on left branch. Sternal gills present on pereonites 2 to 7. Epimeral plate 1 rounded; plates 2 and 3 acuminate. Uropod 3 elongated, peduncle longer than ramus; ramus thin, approximately twice as long as wide. Uropod 1 sexually-dimorphic, with male inner ramus displaying a distinct modified seta (‘copulatory spine’ of Bousfield, 1996). TYPE LOCALITY AND REFERENCE SEQUENCES. Laguna Antofagasta, – 26.1058° S – 67.42058° W, 3338 m a.s.l, Catamarca Province, Argentina. GenBank accession numbers: COI: OR726344 (Fig. 1). ETYMOLOGY. The term “Inca ” in the specific epithet should be interpreted as a noun in conjunction with the generic name, in reference to the Inca Empire, which historically occupied vast areas of South America, including the highland and Puna regions. DESCRIPTION OF MALE Body: smooth. Maximum length observed 9.87 mm. Head: Eye ellipsoid, pigmented. Antenna I (Fig. 9 a, b): shorter than antenna II but longer than its peduncle. Peduncular segments 1–3 progressively shorter, all segments with many simple and plumose setae, along with microtrichs Ib. Flagellum with eleven articles, with groups of simple setae (type A1) and some isolated plumose setae; aesthetascs ordinary occurring distally between articles 8–10. Antenna II (Fig. 9 c): less than half body length. Peduncular segments 3–5 bearing groups of simple and plumose setae. Flagellum comprising 14 articles each bearing distal and subdistal simple setae of type A1. Upper lip: Ordinary, with minute setae on the distal part (Fig. 10 a). Mandible: Right mandible (Fig. 10 b) incisor 5-denticulate (three long, two short); lacinia mobilis complex with many denticles; setal row with 4 pappose setae; molar triturative, well developed. Left mandible (Fig. 10 c) incisor broadened, 5-denticulate; lacinia mobilis 4-denticulate (two long, two short); setal row with six pappose setae. Lower lip: Ordinary, outer lobes covered with minute setae (Fig. 10 d). Maxilla I: Asymmetrical. Outer plate with nine robust serrate setae F4 and setules on the inner surface. Inner plate shorter than outer one, with two apical papposerrate setae, and several marginal setules. Palp of right Maxilla I longer than wide, reaching more than half the length of the distance between the base of the palp and the apex of the outer plate, bearing two simple apical setae (Fig. 10 e). Palp of left maxilla shorter than right counterpart, with only one simple distal seta (Fig. 10 f). Maxilla II (Fig. 10 g): Inner plate slightly shorter than outer plate, with 2 unequal strong pappose setae on inner margin; outer and inner plates with simple and plumose setae distally and few setules on the surface. Maxilliped (Fig. 10 h): Inner plate with three apical robust cuspidate setae; distal and medial margins with plumose setae. Outer plate ovate, longer than first segment of palp; distal and medial margins with simple setae. Palp longer than plates, 4-segmented; segment 3 slender, longer than wide; segments 1–3 bearing both simple and serrated setae on medial margin and lateral margins; segment 4 unguiform, shorter than segment 3, with simple setae shorter than nail placed distally. Gnathopod I (Fig. 11 a): Subchelate, coxal plate longer than wide, margin with small simple setae (type Ia). Basis hind margin with a single simple seta; basis, ischium and merus with denticles type T1 on margins. Posterior margin of basis and ischium with groups of 5 serrated setae. Carpus longer than wide, posterior pectinate lobe bordered with serrate setae. Propodus (Fig. 11 b) longer than broad, hammer-shaped, anterodistal margin with A1- type simple setae, inner face with 10–11 serrate setae type F3 arranged obliquely; palm margin bearing a subrectangular hump near the dactylus, lined with A1- type setae; palm angle with T1- type denticles, and two cuspidate setae with accessory seta. Dactylus with T1- type denticles. Palmar Index (sensu Ruffo [1973]) = 0.37. Gnathopod II (Fig. 11 c): Subchelate. Coxal plate longer than wide. Basis, ischium and merus with groups of simple setae on posterior margin. Carpus subtriangular, notably shorter than propodus. Propodus ovate, with oblique palm; palm margin bordered with several rows of simple setae; palm angle with two cuspidate setae and T1- type denticles. Dactylus claw-like, congruent with the palm. Palmar Index (sensu Ruffo [1973]) = 0.43. Pereiopods 3 and 4 (Fig. 12 a, b): Similar in size. Coxal plates: pereiopod 3 subrectangular, longer than wide; pereiopod 4 broad, excavated posteriorly, 1.2x as long as wide; both coxal plates with margins lined with thin simple setae type Ia; posterior margin of basis, ischium, merus, carpus and propodus with simple or cuspidate setae; dactylus elongated, approximately ½ length of propodus. Pereiopods 5–7 (Fig. 12 c–e): Pereiopod 5 shorter than pereiopods 6 and 7, with the last two being equal in length. Coxal plate of pereiopod 5 bilobated, wider than long, with posterior lobe deeper than anterior lobe; coxa of pereiopod 6 as long as wide, with significantly reduced anterior lobe; coxa of pereiopod 7 wider than long; all coxal plates with thin simple setae along their margins (type Ia). Basis of pereiopods 5–7 expanded and finely serrated, anterior and posterior margin of ischium, merus, carpus and propodus with simple or cuspidate setae and few microtrichs type Ib. Dactylus of all limbs elongated, similar to pereiopods 3–4. Coxal gills: Sacciform, present on gnathopod II to pereiopod 6 (Fig. 12 a–d). Sternal gills also sacciform but shorter, present on pereonites 2 to 7 (Fig. 12 a). Pleopods: Biramous. Peduncle with pair of retinacula. Rami multiarticulate, provided with long plumose setae (Fig. 13 a). Uropod 1 (Fig. 13 b): Peduncle longer than rami, with four dorsal cuspidate setae aligned in a longitudinal row and other three cuspidate setae on dorsolateral and dosomedial distal margin. Rami subequal in length with three dorsal cuspidate setae; inner ramus with seven distal setae, one of which notably elongated, slender and slightly curved, surpassing tip of ramus (‘copulatory spine’ sensu Bousfield [1996]); outer ramus with five distal setae, one of them larger than rest. Uropod 2 (Fig. 13 d): slightly shorter than peduncle of uropod 1. Peduncle slightly longer than rami. Peduncle and both rami each with three dorsal cuspidate setae. Outer ramus with seven distal cuspidate setae, one notably longer and more robust than rest; inner ramus bearing five distal cuspidate setae, one of which longer and stronger than rest. Uropod 3 (Fig. 13 e): subequal in length to peduncle of uropod 2; peduncle rectangular, wider and longer than ramus, with six robust distal setae and two additional marginal setae, all cuspidate. Outer ramus basal width nearly 2.5 times width at tip of ramus, with six to seven simple setae and one shorter cuspidate seta distally; another group of subdistal setae placed close to apex consisting of row of four long, thin simple setae (left uropod 3; Fig. 13 f) or only one seta (right uropod 3) (Fig. 13 e). Telson: subrectangular, with two widely spaced, long simple setae on distal margin (setae serrate in one of male paratypes); additionally, other two short plumose setae placed subdistally on each side (three setae in one of male paratypes) on dorsal surface of telson (Fig. 13 g, h). Epimeral plates (Fig. 13 i): Plate 1 is rounded posterodistally; Plates 2 and 3 are acuminate posterodistally with angle strongly produced. Intraspecific variability in males: Variations were observed, including differences in the setation of ramus of uropod 3, as outlined in the main description. Additionally, in one male an apparent notch was observed on coxa 5, and two setae were absent on the anterodistal part of the gnathopod I propodus. Some individuals exhibited 13 articles in antenna II flagellum (14 in holotype). Further variations were noted in the number and type of setae on the telson, as described in the main text. FEMALE (PARATYPES). Maximum body length observed 7.32 mm. Female gnathopod II propodus (Fig. 11 d) smaller and slenderer than in male, with five serrate setae on the inner face. Oostegites subtriangular, featuring curled setae along margin (Fig. 11 e). Female Uropod 1 without modified seta (‘copulatory spine’) on inner ramus (Fig. 13 c). TAXONOMICAL REMARKS Hyalella oscari sp.n. was discovered in the Puna and High Andes ecoregions, specifically in Catamarca and La Rioja provinces to the east of the Andes, Argentina, at elevations ranging from approximately 3900 to 4400 m a.s.l. This species bears a close resemblance to Hyalella fatimae Isa-Miranda et Peralta, 2022, yet it can be primarily distinguished by distinct morphological features. Notably, H. oscari sp.n. is characterized by the morphology and chaetotaxy of maxilla I palp, particularly the presence of two plumose setae vs. only one seta present in H. fatimae, the former being a feature unique within the genus Hyalella. Additionally, in H. fatimae, the antenna II extends notably longer than the head, about 25% of the body length, whereas in H. oscari sp.n., it is only slightly longer. The propod of male gnathopod I of H. oscari sp.n.