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Hyalella cuyana n. sp (Figs 2–8) Type Locality. Argentina, Calingasta River, San Juan Province, Calingasta Department: Calingasta River (hyporheic) Well Nº1: 31°20′30.7′′S, 69°25′38.1′′ W, 1373 m a.s.l. Material examined. Type material. Holotype: male = 3.9 mm, FML-CRUST 01282. Paratype: 1 male = 4.3 mm, FML-CRUST 01283; 1 female ovigerous with 3 immatures in the pouch = 5.2 mm, 1 female = 4.3 mm, FML-CRUST 01284. All type materials were collected on 6 Nov 2014 by M. Peralta and A. Franck Colombres. Additional material: 12 immatures, FML-CRUST 01285; 13 immatures, FML-CRUST 01281; 1 female = 5.08 mm and 5 immature, FML-CRUST 01291. Same collection data as the type material. Etymology. The specific epithet is an adjective derived from the Huarpe term “cuyo” which means “land of the sands” and refers to the name of the Argentine region of Cuyo (area comprising the provinces of San Juan, Mendoza and San Luis), where the species is probably endemic. Diagnosis. Eyes absent.Antenna 1 and antenna 2 of similar size, aesthetascs elongated. Coxal plate of pereiopod 4 posteriorly without excavation. Epimeral plates 1–3 rounded posterodistally. Male gnathopod 2 propodus almondshaped, ovate, palm slope strongly oblique. Pleopods inner ramus reduced to two articles in pleopod 1 and three in pleopods 2–3. Description of holotype male. Body length 3.9 mm (Fig. 2B). Head smaller than the first two thoracic segments combined. Eyeless. Body surface smooth. Epimeral plates 1–3 with rounded posterodistally (Fig. 3B). Pereiopodal coxae 1 to 3 subequal in shape, slightly over-lapping. Coxal plates 1–4 in lateral view, as deep as the associated pereionite.Acumination in coxae absent. Coxa 3 narrower than 4. Coxa 4 subquadrate, without posterior excavation. Posterior lobe of coxa 5 deeper than anterior lobe. Anterior lobe of coxa 6 small (Figs 6A–D). Antenna 1 (Fig. 3C) subequal in size to antenna 2. Peduncle slightly shorter than head, peduncular segments 1–3 progressively shorter, all segments with simple and plumose setae. Flagellum with ten articles bearing groups of simple setae, additionally with aesthetascs occurring distally between articles 1–9, elongated, reaching about ½ to 3 / 4 length of the antennal article. Antenna 2 (Fig. 3D) less than half of body length. Peduncle longer than peduncle of antenna 1, peduncular segments 4–5 of similar length with simple and plumose setae. Flagellum with eight articles bearing groups of simple setae. Labrum (Fig. 4B) anterior margin covered sparsely by simple setules. Mandibles basic amphipodan type (sensu Watling 1993). Right mandible (Fig. 4E) with incisor 8-denticulate (three long, five short), lacinia complex, setal row with two pappose setae. Left mandible (Fig. 4D) with incisor 7- denticulate (three long, four short), lacinia 4-denticulate, setal row with three pappose setae. Both mandibles have well-developed, cylindrical, triturative molar; mandibular palp rudimentary, reduced to a small blunt process. Lower lip (Fig. 4C). Outer lobes and mandibular process rounded; lobes covered by sparse setules. Inner lobes wanting. Maxilla 1 (Figs 4F–G). Palp short, unsegmented, longer than wide, reaching less than half the length of the distance between the base of the palp and the apex of the outer plate, with a strong distal seta. Inner plate shorter than outer one, with two apical papposerrate setae, and several marginal setules. Outer plate with nine stout serrate setae. Maxilla 2 (Fig. 4H), both plates subequal in size. Inner plate with one strong, long papposerrate seta proximally on inner margin. Outer and inner plate sparsely setulose, with apex wearing simple, serrulate, pappose and serrate setae as figured. Maxilliped (Fig. 4A). Inner plate longer than wide, reaching ¾ of length of outer plate, with three long robust cuspidate setae apically and other pappose and simple setae and setules on apex and margins; outer plate with apical and medial simple setae; palp 4-segmented, second segment longer than wide, all segments with simple or serrate setae on inner and outer margins; third segment with distal and inner margins with cluster of several simple or serrate setae; fourth segment unguiform with long distal nail. Coxal gills sacciform, present on gnathopod 2 (Fig. 5B) to pereiopod 6 (Fig. 6A–D). Sternal gills tubular, present on pereonites 3 to 7. Gnathopod 1 (Fig. 5A) subchelate. Coxal plate longer than broad, margin with small simple setae. Basis, ischium and merus with 1–2 serrate setae on posterior margin. Carpus longer than wide, concave posterior lobe bordered by pectinate and serrate setae. Propodus longer than its maximum width, hammer-shaped, without comb/ setose-scales, anterodistal border bearing a group of thin simple setae, inner face with five serrate setae in oblique row; palm slope slightly transverse; palm angle with three endal, cuspidate setae with accessory seta. Claw-like outer margin of dactylus with one thin plumose seta dorsally, inner margin with denticles. Palmar Index (sensu Ruffo 1973) = 0.46. Gnathopod 2 (Fig. 5B) subchelate. Coxal plate narrow, about as long as wide, with thin setae. Basis, ischium and merus with 1–2 simple setae on the posterior margin. Posterior lobe of carpus elongated, margin pectinate with some serrate setae. Propodus ovate, almond-shaped, palm slope strongly oblique, margin evenly and slightly convex, fringed by numerous apical setae, some cuspidate with accessory seta and others simple. Dactylus claw-like congruent with palm, with one thin plumose seta dorsally. Palmar Index (sensu Ruffo 1973) = 0.63 Pereiopods 3 and 4 (Figs 6A–B), similar in size and shape. Coxal plates sub-quadrate in shape, coxa 4 posteriorly without prominent excavation; merus, carpus and propodus posterior margin with simple setae, additionally merus of pereiopod 3 and basis of pereiopod 4 with plumose seta. Dactylus less than half of propodus length. Pereiopods 5–7 (Figs 6C–E). Pereiopods 6–7 significantly longer than pereiopod 5. Coxal plate of pereiopod 5 bilobed with one seta on anterior and posterior lobe, basis anterior margin with two to three serrated setae; coxa of pereiopod 6 weakly bilobed with one seta on posterior lobe; pereiopod 7 coxa wider than long, basis posterior margin with a notch bearing two thin simple setae. Anterior and posterior margins of merus, carpus and propodus of pereiopods 5–7 with marginal clusters of 2–8 cuspidate setae. Basis posterior margin of pereiopod 7 with a notch bearing two thin simple setae. Pleopods (Fig. 7A). Peduncle with retinacula. Biramous, inner ramus shorter than peduncle, reduced to two articles in pleopod 1 and three in pleopods 2 to 3, outer ramus of pleopods 1–3, with 7 articles, rami bearing long plumose setae. Uropod 1 (Fig. 7B). Peduncle 1.5 times longer than rami, with a dorsal row of six cuspidate setae with accessory seta, and others two distal setae; rami subequal in size; inner ramus with one dorsal and six distal cuspidate setae (two of them much longer), modified curved seta on inner side of ramus wanting; outer ramus with 3–4 dorsal and four distal cuspidate setae, one of them longer. Uropod 2 (Fig. 7C) shorter than uropod 1. Peduncle slightly shorter than rami, with four cuspidate setae with accessory seta; inner ramus with one dorsal and five distal cuspidate setae; outer ramus with two dorsal and four distal cuspidate setae, one of them shorter. Uropod 3 (Fig. 7D) length similar to peduncle of uropod 2; peduncle as wide as long, with two distal setae, one cuspidate and other simple; ramus shorter than peduncle, with three distal cuspidate setae. Telson (Figs 7E–F) wider than long, entire, with two robust apical cuspidate setae and 2–3 very slender simple lateral setae arranged in a submarginal row. Female (paratypes). Body larger than male, mean body length 4.86 mm (n = 3). Habitus similar to male except for gnathopod 2, which displays more elongated propodus, inner face of propodus with 5–6 serrate setae in oblique row (Fig. 5C) (right propodus with six). Oostegites subtriangular, in one female mature (body length 5.2 mm) are equipped with curled setae on the margins, in other female (body length 4.3 mm) without such setae. Antenna 1 flagellum with 11–14 articles. Antenna 2 flagellum with 11 articles. Suspected sexual differences in the number of setae on uropods 1–2 rami (females with an additional dorsal seta in relation to the males) pending confirmation given that only a small sample of adult specimens was available. Habitat. Freshwater, hyporheic. Taxonomic remarks. Hyalella cuyana n. sp. can be distinguished from the other species of the genus by the combination of characters given in the diagnosis, some of which differ from the diagnosis of Hyalella and the description of generic characters provided by González & Watling (2001): Antennae 1 and 2 subequal in size, and coxal plate of pereiopod 4 posteriorly without excavation. In relation to the latter characters, in epigean species H. pauperocavae González & Watling, 2002 the coxal plate 4 also presents an uncommon shape for the genus, with a slightly excavated posterior margin, and its antennae are subequal in size. Hyalella pauperocavae shows some other similarities with H. cuyana n. sp., namely, sternal gills present on pereonites 3–7; palp of maxilla 1 longer than wide, reaching less than half the distance between base of palp and tip of setae on outer plate; gnathopod 2 palm slope oblique; outer ramus of uropod 3 shorter than peduncle; and modified curved seta on inner side of ramus wanting. However, H. pauperocavae is distinguished from H. cuyana n. sp. by having pigmented eyes, the maxilliped inner plate with three not very long cuspidate setae apically, inner surface of gnathopod 1 propodus with ten serrated setae (vs five setae), telson with six to eight setae distributed asymmetrically on apical margin (vs two setae), well developed pleopods, and pereiopods 6 and 7 not significantly longer than pereiopod 5. In its general morphology, H. cuyana n. sp. is similar to other hypogean congeneric species by presenting: reduction of ommatidia or total absence of eyes (except in H. paramoensis Andres, 1988); dorso-posterior carina on pleonite 1–3 absent (except H. cenotensis Marrón-Becerra, Hermoso-Salazar & Solís-Weiss, 2014); two terminal setae on inner plate of maxilla 1, typical of the genus Hyalella (except H. cenotensis); gnathopod 2 of male without lobiform process on palmar corner (except H. muerta Baldinger, Shepard & Threloff, 2000); reduction of the size of uropod 3; few or no apical setae on telson; reduction of inner ramus of pleopod (only in H. rionegrina Grosso & Peralta, 1999; H. muerta and H. cuyana n. sp.); attenuation of the coxae plates, especially in pereiopod 4 (only in H. muerta and H. cuyana n. sp.), it should be noted that these features are not mentioned or illustrated in the original descriptions of H. formosa Cardoso & Araujo, 2014 in Cardoso et al. (2014), H. spelaea Bueno & Cardoso, 2011 in Cardoso et al. (2011) or H. caeca Pereira, 1989. H. veredae Cardoso & Bueno, 2014 in Cardoso et al. (2014) is the only Hyalella stygobiont species that shares with the new species the character of antennae 1 and 2 subequal in length, although it is easily distinguishable by the posterior excavation of the coxal plate 4 (not developed in H. cuyana n. sp.) and the modified curved setae on the inner ramus of uropod 1 of the male (absent in H. cuyana n. sp.). Furthermore, the new species has elongated aesthetascs (similar to H. epikarstica Rodrigues, Bueno & Ferreira, 2014; H. formosa; H. veredae and H. troglofugia Bastos-Pereira, De Oliveira & Ferreira, 2018). The newly described species is similar to H. epikarstica and H. troglofugia in having the maxilliped inner plate with three very long cuspidate setae apically. Furthermore, H. muerta has the male gnathopod 2 palm excavated, which makes it easily distinguishable from H. cuyana n. sp. The distribution of sternal gills in Hyalella is generally used when describing and comparing species. In H. cuyana n. sp.; H. montana Rodrigues, Senna, Quadra & Bueno, 2017; H. epikarstica; H. imbya Rodrigues & Bueno, 2012 in Rodrigues et al. (2012); and H. muerta the sternal gills are developed on pereonites 3–7. Table 1 presents a detailed morphological comparison between the 14 stygobiont or stygophile Hyalella species that are in the process of adaptation to the hypogean habitat (Rodrigues et al. 2017). Some of the characters included in Table 1 have not been included in the species original descriptions (e.g. development of aesthetascs; shape of coxal plate 4) or are male characters that are unknown in H. rionegrina and H. anophtalma Ruffo, 1957 (for which only females are known). The morphology of the gnathopod 2 propodus of male H. cuyana n. sp. is similar to those of H. meinerti Stebbing, 1899 (epigean); H. caeca (cavernicolous); and H. imbya (hypothelminorheic). These species share the condition of having a strongly oblique palm slope in the gnathopod 2 propodus of males. However, H. meinerti and H. imbya differ from the new species by having the coxal plate 4 excavated posteriorly. H. meinerti differ from the new species in having well developed eyes; antenna 1 shorter than antenna 2; uropod 3 outer ramus longer than peduncle, and arrangement of the telson (without lateral setae). H. imbya is differentiated from the new species mainly in having antenna 1 longer than antenna 2; very short palp of maxilla 1; inner face of gnathopod 1 propodus with seven serrated setae (vs five setae). The new species also differs from H. caeca mainly in having antenna 1 much shorter than antenna 2 (antennae 1 and 2 similar in H. cuyana n. sp.); inner face of gnathopod 1 propodus with seven serrated setae (vs five setae); telson with two short apical setae (vs two long and strong apical setae and three lateral setae). Comments about adaptation of Hyalella cuyana n. sp. to subterranean environments . The animal species that inhabit caves and other subterranean (aquatic and terrestrial) environments exhibit similar reductive (Romero & Green 2005) and constructive traits (Jones & Culver 1989) arisen via convergent evolution. The repeated independent evolution of such traits in different taxa provides strong evidence that they are related to a common environmental condition, i.e. the complete absence of light, shared by subterranean taxa (Carlini & Fong 2017). These convergences are a potential critical issue in the reconstruction of phylogenetic relationships in groups with epigean and hypogean species, as is the case of Hyalella. The absence of eyes in Hyalella is typical of obligate groundwater-dwelling species (Bastos-Pereira et al. 2018), but this pattern presents some exceptions such as, for example, the presence of eyes in H. cenotensis which was collected in open water (accidental occurrence?) or the reduced number of ommatidia in the eyes of H. spelaea (cavernicolous). In almost all the species related to subterranean habitats included in Table 1, the pereiopods 6–7 are significantly longer than pereiopod 5. Elongation of appendages is a widespread trend in stygobiont amphipods (Väinölä et al. 2008). Likewise, the increased length of the thoracic appendages and antennae of cave-dwelling species has traditionally been explained as a consequence of selection for non-visual senses and an increased ability to find food in a low-energy environment (Culver & Pipan 2009; Culver et al. 2010; Hüppop 2000). Nevertheless, results from Delić et al. (2016) suggest that, rather than being a general adaptation to cave life, long appendages such as pereiopods 5–7, appear to be associated with the absence of water flow, as well as with character displacement when in sympatry with ecologically similar competing species. Regarding the development of sensory structures, the antennae of H. cuyana n. sp. bear long aesthetascs. These are complex sensilla harboring chemoreceptor neurons (Tiernery et al. 1986; Sandeman & Sandeman 1996). Studies by Ziemba et al. (2003) have shown that the length of individual aesthetascs of cave-dwelling crayfish of the genus Orconectes was greater in O. australis packardi compared to the surface-dwelling species Orconectes cristavarius. These observations suggest that the neurons of O. a. packardi may be exposed to more chemical signals, which could favor the specialization for greater sensitivity. In the case of Hyalella, this raises the question, to be explored in the future, whether there is a relationship between the length of aesthetascs in hypogean species and environmental variables. In addition, stygobiont amphipods like H. cuyana n. sp. show structural rudimentation, e.g. in the pleopods. According to Botosaneanu (2001) the reduction of pleopod size can be associated, at least in many cases, with reduction or loss of the natatory ability of these appendages. Only tree prejuvenile individuals were observed in the marsupium of the female ovigerous paratype of Hyalella cuyana n. sp. (Fig. 8). In the description of the only known ovigerous female of H. anophthalma, Ruffo (1957) comments that the low number of eggs found in the pouch, in combination with the considerable size of the eggs themselves, may be also considered characteristics connected with the subterranean habitat. Additionally, fewer and larger eggs and offspring have also been reported in other subterranean amphipods. Fišer et al. (2012) found that cave-dwelling Niphargus females lay more voluminous eggs and their brood volume was significantly larger. Larger Niphargus females appear to allocate excess energy to more voluminous eggs rather than to a greater number of eggs. The volume of an egg often correlates positively with its nutritional value, which lengthens the development within the egg. In turn, this results in larger juveniles, with greater fitness and probably greater ability to cope with the challenges of the subterranean environment. Further studies are needed to elucidate how local and specific abiotic and biotic conditions of sub-superficial environments, such as hyporheic habitats, may be related to particular features of the Hyalella species that inhabit them. Distributional and biogeographical remarks on Hyalella cuyana n.

The freshwater amphipod of the genus Hyalella is typical from continental American waters and shows high levels of endemicity and Brazil has the second largest diversity. A new species is described here, Hyalella longipropodus n. sp. that occurs in a spring of southern Brazil in the municipality of Palmeira das Missões, in the northwestern region of state of Rio Grande do Sul, southern Brasil. Hyalella longipropodus n. sp. shows the following character states: antenna 2 more than half body length, gnathopod 2 propodus elongated, uropod 1 inner ramus of male without apical curved setae, uropod 3 peduncle with seven strong distal setae with accessory setae, ramus of uropod 3 with ten cuspidate setae with accessory setae. Hyalella longipropodus n. sp. occurs in sympatry with H. gauchensis, but these differ especially in the size and shape of gnathopod 2, the presence of curved setae on uropod 1 in H. gauchensis and the absence in H. longipropodus n. sp., antenna length (longer in H. longipropodus n. sp.) and number of cuspidate setae on uropods 1, 2, and 3. Besides the morphological differences, H. longipropodus n. sp. presented genetic differences always above 19% for the COI gene and 29 % for the 16S rRNA gene, when compared with other species found in the northwestern region of the state of Rio Grande do Sul, showing that it is really a species not yet described by science.

The knowledge of the diversity and distribution of Hyalella species is scarce in the subtropical regions of Brazil. The present study investigated the diversity and distribution of Hyalella species...

Hyalella villalobosi sp. nov. http://www.zoobank.org/ urn:lsid:zoobank.org:act: E4237141-1948-4D18-A6F3 -7AFB6F5592F8 (Figures 11–13) Etymology. The new species is named in honour of Dr José Luis Villalobos Hiriart, in recognition of his valuable and outstanding contributions to the marine and freshwater carcinology of Mexico. Material examined. Holotype male, size 5.4 mm (Cat. No. CNCR 35729), from Lake Catemaco in state of Veracruz, Mexico (18.366°N, 95.084°W), 24 July 2015, 337 m a.s.l., temp. 34°C, pH 7. Collectors: A. Marrón-Becerra, E. Lemus-Santana and M. HermosoSalazar. Paratypes (n = 30 males, n = 30 females): males – mean body total length 5.1 ± 0.5 mm, mean head length 0.6 ± 0.03 mm (n = 27), females – mean body total length 4.5 ± 0.5 mm, mean head lenght 0.5 ± 0.04 (n = 30) (permanent slides Cat. No. CNCR 35739, paratypes and SEM preparations CNCR 35740), locality same as holotype. Type locality (Figure 1). Lake Catemaco, state of Veracruz, Mexico (18.366°N, 95.084°W). Diagnosis. Pleonite 1 and 2 with dorsoposterior carina. Coxa 4 excavated posteriorly. Eyes pigmented. Antenna 1 shorter than antenna 2. Antenna 2 less than half body length. Maxilla 1 palp short, overreaching half of length between base of palp and base of setae in outer plate, with 1 short stout distal seta and setules; inner plate slender with 3 strong pappose distal setae. Maxilla 2 inner plate with 2 strong pappose setae on inner margin. Gnathopod 1, propodus hammer shaped, palm slope transverse, inner face with 2 pappose setae, comb scales on distoposterior and distoanterior border, carpus inner face lobe with 5 pappose setae. Gnathopod 2, basis hind margin with 1 medial seta, excavation of palm wide. Uropods without curved setae. Uropod 3, peduncle longer than ramus, styliform. Telson as long as wide, distal margin acute, with 2 long simple apposed setae. Coxal gills on segments 2–6. Sternal gills on segments 3–7. Description Body (Figures 11a, and 18a), tergites of pleon 1 and 2 with dorsoposterior carina. Epimeral plates 1–3 slightly acuminate. Coxae 1–3 (Figures 11a, and 18a) subequal in shape, subrectangular, longer than wide; coxa 1 shorter than coxae 2–3; coxa 4 wider than coxae 1–3 with deep posterior excavation, acumination absent; coxa 5 with two subequal lobes, anterior lobe slightly shorter than posterior; coxa 6 anterior lobe reduced; coxa 7 anterior lobe absent. Head typically gammaridean (Figures 11a, and 18a), shorter than first two thoracic segments, rostrum absent. Eyes pigmented, medium, rounded, located between insertions of antennae 1 and 2. Antenna 1 (Figure 11a–b) less than half the body length, shorter than antenna 2, but longer than peduncle of antenna 2, almost reaching to middle of third pereonite; peduncle longer than head, reaching to middle of length of first pereonite; article 1 and 2 subequal in length, article 1 wider than articles 2–3, article 2 longer and wider than article 3, proportions (1.3:1.26:1), article 1 with 3 short setae, 1 smaller, and one cluster with 3 cuspidate setae ventrally at distal end, articles 1–3 mid-ventral margin with slender setae; flagellum longer than peduncle with 9 articles gradually shorter towards distal portion; aesthetascs on flagellum, present on articles 2–6 (one pair), 7–8 (one). Antenna 2 (Figure 11a, c) almost 1.27 times longer than antenna 1, reaching one-third body length, reaching fourth pereonite; peduncle reaching second pereonite, peduncle articles increase gradually in length and decrease in width; article 3 shorter but wider than 4 and 5, article 4 longer than article 3, article 5 slightly longer than article 4; flagellum with 8–10 articles slightly longer than peduncle (subequal), without aesthetascs. Buccal parts: upper lip (Figure 11f), distal margin rounded with numerous setules. Lower lip (Figure 11g) subquadrate, outer lobes without notches or excavations; mandibular projection of outer lobes rounded. Mandibles (Figure 11h–i) without palp, asymmetric. Incisor toothed, 6 teeth present. Left lacinia mobilis, with 5 teeth; setal row on left mandible with 3 main pappose setae plus accessory setae. Right mandible with 6 teeth, right lacinia mobilis reduced than left, with 2 pairs of asymmetric L-shape teeth; setal row on right mandible with 2 main pappose setae plus accessory setae and with setulae near molar process. Both molar processes large, cylindrical and triturative, with accessory pappose setae. Maxilla 1 (Figures 11d, and 19e), palp vestigial, uniarticulate, longer than wide, distally pointed and with 1 distal stout distal seta (A 5 type), setules present; palp length overreaches half of the distance between base of palp and base of seta on outer plate, or reaching to middle; inner plate slender, shorter than outer plate, with 3–4 pappose distal setae (2 distal and 2 subdistal); outer plate with 9 distal stout serrate setae and with setules. Maxilla 2 (Figure 11e) plates subequal; inner plate shorter and slender with 2 pappose setae on mid-distal inner margin, and with 6 serrulate setae on distal margin; outer plate without serrate setae but with 2 long pappose setae; outer and inner plates with abundant large simple setae (type A2) and setules on both distal surfaces and margins. Maxilliped (Figures 11j, and 20e) inner plate lobe longer than outer plate lobe; distal margin slightly convex; inner plate distal margin with 3 cuspidate setae of equal size and with plumose setae, inner margin with several pappose setae; outer plate, inner and distal margins with numerous simple setae. Palp composed of four articles subequal in maximum length; first article with 2 simple setae at the inner distal end and 1 seta at outer distal end; second article with numerous simple setae on inner margin and 1 on outer distal end; third article with several long setae on distal margin, outer margin with 1 simple seta and comb scales, inner margin with 5 setae and 5 at distal end; fourth article unguiform slightly longer than nail, with comb scales, inner margin near distal half with 3 setae, and 2 setae near nail base on outer margin; nail exceeds two-thirds of fourth article, with serration at distal half. Gnathopod 1 (Figure 12a) subchelate, hammer shaped. Basis elongated, maximum length almost 3 times longer than maximum width posterior margin with 2 setae, distal end without cluster of setae. Ischium short, subquadrate; distal posterior end with one cluster of 2 setae. Merus longer than wide, ventral surface with comb scales; distal margin with 8 setae. Carpus longer than wide, longer than propodus; with strong, short, and wide posterior lobe forming one scoop-like structure open to inside; inner surface with 5 serrate setae. Propodus less than 1.5 times longer than wide (1.36 times); inner surface near distal margin with 2 serrate setae in one row, distal anterior end with 2 clusters of approximately 8 setae; distal anterior and posterior surfaces with comb scales; palm transverse, posterior distal end with 1 robust seta and cup for dactylus. Dactylus clawlike; nail present; with 1 plumose seta, with comb scales. Gnathopod 2 (Figures 12b, and 21e) subchelated; palm slightly oblique. Basis elongate, more than 3 times longer than wide; posterior margin with 0–1 medial seta. Ischium short, subquadrate, shorter than merus. Merus short, posterior margin with 8 simple setae, posterior inner and outer surfaces with comb scales. Carpus shorter than propodus; anterodistal end with 6 setae; posterior lobe scoop-like, elongate, length similar to merus maximum length, almost 1.5 times width of merus, with several submarginal pappose setae and comb scales. Propodus robust, almost 1.5 times as long as wide, subrectangular; palm similar length to or slightly longer than posterior margin; slope slightly irregular, with several long simple setae, and some short and medium setae; distal margin of palm with one truncated process near insertion of dactylus, and with wide posterior excavation at base (Figure 22e); palm posterior distal end with 2 strong setae, comb scales and cup for the dactylus. Dactylus claw-like, congruent with palm without comb scales; outer margin with 1 plumose seta; inner margin crenulated, with setules. Pereopods 3–7 (Figure 12e–i) simple, gradually longer posteriorly. Pereopod 5 slightly shorter than 4 and 6. Pereopod 3 (Figure 12e) basis elongate; mid-posterior margin without simple seta. Merus anterior margin almost at half with 1 seta; posterior margin with 3 long simple setae; anterodistal and posterodistal ends with one cluster of 4 and 7 setae, respectively. Carpus slightly shorter and slenderer than merus; posterior margin with 2 stout setae plus accessory setae; posterodistal end with at least 7 slender setae, anterodistal end with at least 6 setae. Propodus, slenderer than carpus; posterior margin with 3 stout setae; anterodistal end with 5 simple setae. Dactylus claw-like; length less than half of propodus; nail present. Pereopod 4 (Figure 12f) similar in shape to pereopod 3 but slightly longer; coxa 4 wider than coxa 3 with posterior excavation; basis posterior margin without simple seta; merus mid-anterior margin without setae; propodus posterior margin with 3 stout setae. Pereopods 5–7 (Figure 12g –i) similar in shape; basis posterior lobe rounded and denticulated. Pereopod 7 (Figure 12i) basis lobe widely expanded, overreaching ischium distal margin; basis lobe width 1.7 times as wide as basis (measured at cleft between basis and basis lobe); posterior margin with 13 serrations with setules and without stout seta on distal margin; anterior margin with 2 stout setae and one cluster of 2 setae at distal end. Dactylus length almost one-third of propodus length. Pleopods 1–3 (Figure 13e) not modified, biramous, elongated, rami multi-annulated, with numerous plumose setae; pleopod 1, inner margin of peduncle at distal end with 2 short retinacula (coupling hooks). Uropod 1 (Figure 13a) longer than uropod 2; peduncle longer than rami, dorsal margin with 2 dorsal setae, inner and outer distal ends each with 1 seta; rami subequal, inner ramus slightly longer, with 2 dorsal and 5 distal setae; outer ramus with 2 dorsal and 3 distal setae; male without curved setae on inner ramus. Uropod 2 (Figure 13b) as long as peduncle of uropod 1; peduncle shorter than outer rami, with 1 dorsal seta and 1 seta at distal end; rami subequal, inner ramus slightly longer with 2 dorsal and 6 distal setae, outer ramus with 2 dorsal and 4 distal setae. Uropod 3 (Figures 13c, and 23e) slightly longer than or as long as peduncle of uropod 2; peduncle rectangular, wider than ramus, with 5 strong distal setae of variable length; inner ramus absent; outer ramus uniarticulate, slender, slightly shorter than peduncle; basal width almost 3 times width of apex of ramus, with 3 slender apical setae (one longer) and 1 connate seta. Telson (Figures 13d, and 24e) entire, longer than wide, distal margin pointed or truncated, with 2 long simple apposed setae; outer surface bearing two clusters of 3 plumose setae, near margin, symmetrically distributed. Coxal gills sac-like, present on segments 2–6. Sternal gills tubular, present on segments 3–7. Female (Figure 18b) similar to male. Gnathopod 1 (Figure 12c), carpus with 7 serrate setae on inner face lobe; propodus with 4 serrate setae in row over inner face. Gnathopod 2 (Figure 12d) smaller than male gnathopod 2, parachelated, palm reverse oblique, basis posterior margin without seta; propodus longer than twice maximum width, inner face with 4 serrate setae in a row and 1 simple seta, outer face with 4 setae in one row and 3 large setae near palm, anterior and posterior distal half with comb scales. Pereonite 2 with anterior excavation or notch for amplexus. Pereopod 7 lobes with 11 serrations and setules, and without stout setae on distal margin. Oostegites subtriangular with curled setae on margins. Habitat. Freshwater, epigean, littoral, associated with sediment and Eichhornia crassipes (Mart.) Solms. Distribution. Lake Catemaco, state of Veracruz, Mexico (18.366°N, 95.084°W). Remarks This species has parasites of the genus Lagenophrys, possibly Lagenophrys patina (Stokes, 1887); they are abundant in the coxae and the basis of pereopods; the protozoos are even attached to the setae. This species is morphologically similar to H. azteca, with two dorsal mucronations on the pleon and the telson with the distal margin acute with 2 distal apposed setae. But this species differs in the following: telson is longer than wider, isquium is longer than its width, uropod 2 is similar in length to peduncle of uropod 1, peduncle is shorter than ramus in uropod 2, and this species has more articles in the antennae despite its shorter size (Tables 1, S1)., Published as part of Marrón-Becerra, Aurora & Hermoso-Salazar, Margarita, 2022, Morphological comparison and description of five new species of Hyalella (Crustacea: Amphipoda) from Veracruz and Mexico City, pp. 1215-1263 in Journal of Natural History 56 (25 - 28) on pages 1239-1245, DOI: 10.1080/00222933.2022.2078241, http://zenodo.org/record/7087076

Hyalella sarukhani sp. nov. http://www.zoobank.org/ urn:lsid:zoobank.org:act: 7B0E06D1-9F55-4345-9055- 9054F8B9B450 (Figures 2–4) Etymology. The new species is named in honour of Dr José Sarukhán in recognition of his outstanding contribution to the study of the biodiversity of Mexico. Material examined. Holotype male, size 7.7 mm (Cat. No. CNCR 35726), from Lake Chapultepec (19.424°N, 99.187°W), 10 August 2016, 2253 m a.s.l. collector: A. Marrón-Becerra. Paratypes (n = 10 males, n = 10 females): males – mean size 6.4 ± 0.5 mm, mean head length: 0.6 ± 0.03 mm (n = 10), females – mean size 6.2 ± 0.4 mm, mean head length 0.5 ± 0.04 (n = 10) (permanent slides Cat. No. CNCR 35731, paratypes and SEM preparations Cat. No. CNCR 35732), locality same as holotype. Other material revised Xochimilco (19.264°N, 99.094°W), 10 August 2016, 2240 m a.s.l., collector A. Marrón-Becerra (Cat. No. CNCR 35733). Lake Chalco, Mexico City (19.264°N, 98.974°W), 29 March 2016, 2231 m a.s.l., temp. 24°C, pH 8.7, conductivity 1793 µS/cm, dissolved oxygen 2.8 mg /L, collectors: A. Marrón-Becerra and F. Charqueño-Celis (Cat. No. CNCR 35734). Type locality (Figure 1a). Lake Chapultepec, Mexico City, Mexico (19.424°N, 99.187°W). Diagnosis. Pleonite 1 and 2 with dorsoposterior carina. Coxa 4 excavated posteriorly. Eyes pigmented. Antenna 1 shorter than antenna 2. Antenna 2 less than half body length. Maxilla 1 palp short, reaching less than half of length between base of palp and tip of setae in outer plate, with 1 short stout distal seta and setules; inner plate slender with 2– 3 strong pappose distal setae. Maxilla 2 inner plate with 2 strong pappose setae on inner margin. Gnathopod 1, propodus hammer shaped, palm slope transverse, inner face with 5–6 serrate setae, comb scales on distoposterior and distoanterior border, carpus inner face lobe with 5 serrate setae. Gnathopod 2, basis hind margin with 3–5 setae, merus with 1 medial seta, excavation of palm wide. Uropods without curved setae. Uropod 3, peduncle and ramus subequal in length, styliform. Telson slightly wider than long, distal margin rounded with 2 long simple setae widely separated. Coxal gills on segments 2–6. Sternal gills on segments 3–7. Description of male Body (Figures 2a, and 17a), tergites of pleon 1 and 2 with dorsoposterior carina. Epimeral plates 1–3 acuminate. Coxae 1–3 (Figures 2a, and 17a) subequal in shape, subrectangular, longer than wide; coxa 4 wider than coxae 1–3, with deep posterior excavation; acumination absent; coxa 5 with two subequal lobes, anterior lobe slightly shorter than posterior, coxa 6 anterior lobe reduced. Head typically gammaridean (Figures 2a, and 17a), shorter than first two thoracic segments, reaching to middle of second pereonite, rostrum absent. Eyes pigmented, black, medium, rounded, located between insertions of antennae 1 and 2. Antenna 1 (Figure 2a–b) less than half the body length, shorter than antenna 2, but longer than peduncle of antenna 2, almost reaching to middle of third pereonite; peduncle as long as head; article 1 and 2 subequal in length, article 1 wider than articles 2–3, article 2 longer and wider than article 3, (proportions 1.8:1.6:1), article 1 with 2 short cuspidate setae ventrally, 1 smaller, and one cluster with 3 cuspidate setae at distal end; flagellum longer than peduncle with 9–10 articles gradually shorter towards distal portion; aesthetascs present on articles 4–7 (one pair), and 8–9 (one aesthetasc). Antenna 2 (Figure 2a, c) almost 1.3 times longer than antenna 1, slightly shorter than one-third body length, reaching fourth pereonite; peduncle almost reaching to middle of first pereonite, peduncle articles increase gradually in length and decrease in width; article 3 shorter but wider than 4 and 5, article 4 slightly longer than article 3, article 5 longer than article 4 (almost 1.5 times); flagellum with 11–12 articles, longer than peduncle (almost 1.5 times); without aesthetascs. Buccal parts: upper lip (Figure 2f) distal margin rounded, with numerous setules. Lower lip (Figure 2g), subquadrate, outer lobes without notches or excavations; mandibular projection of outer lobes rounded. Mandibles (Figure 2h–i) without palp, asymmetric. Incisor toothed, 6 teeth present. Left lacinia mobilis with 5 teeth; setal row on left mandible with 3 main pappose setae plus accessory setae. Right mandible with 6 teeth, right lacinia mobilis reduced, with 2 pairs of asymmetric L-shaped teeth; setal row on right mandible with 2 main pappose setae plus accessory setae and with setulae near molar process. Both molar processes large, cylindrical and triturative, with accessory pappose setae. Maxilla 1 (Figures 2d, and 19b), palp short, uniarticulate, longer than wide, distally pointed with 1 short and stout distal seta, setules present; palp length almost half of distance between base of palp and base of seta on outer plate, but less than half distance between base of palp and tip of seta on outer plate (Figures 2d, and 19b); inner plate slender, shorter than outer plate, with 2–3 pappose distal setae; outer plate with 9 stout serrate setae and with setules. Maxilla 2 (Figure 2e) plates subequal; inner plate shorter and slender, with 2 pappose setae on mid-distal margin, and with 7 shorter serrulate setae on distal margin; outer and inner plates with large simple distal setae (type A2) and abundant setules on both distal surfaces and margins. Maxilliped (Figures 2j, and 20b) inner plate lobe longer than outer plate lobe; distal margin slightly convex, on both plates; inner plate distal margin with 3 cuspidate setae of equal size and with plumose setae, inner margin with several pappose setae; outer plate, inner and distal margins with numerous simple setae. Palp composed of four articles subequal in maximum length; first article with 3 simple setae at inner distal end and 1 seta at outer distal end; second article with numerous simple setae on inner margin and 3 on outer distal end; third article with several setae on distal margin, distal end of outer margin with 3 simple setae and comb scales, inner margin with at least 12 setae and 6 at distal end; fourth article unguiform, longer than nail, with comb scales; nail almost reaching 2/3 of fourth article, with serration at distal half. Gnathopod 1 (Figure 3a) subchelate, hammer shaped. Basis elongated, maximum length almost 3.5 times longer than maximum width; posterior margin with 1 seta, distal end with one cluster of 2 setae. Ischium short, subquadrate, distal posterior end with 2 clusters of 2 setae. Merus longer than wide, almost distal half of length of ventral surface with comb scales; distal margin with 5–6 setae. Carpus longer than wide, longer and slightly wider than propodus; with strong, short, and wide posterior lobe forming one scoop-like structure open to inside; inner surface with 5–6 serrate setae, Propodus 1.5 times longer than wide; inner surface near distal margin with 5–6 serrate setae in one row; distal anterior end with two clusters of approximately 5 setae; distal anterior and posterior surfaces with comb scales; palm transverse, posterior distal end with 1 robust seta and cup for dactylus. Dactylus claw-like; nail present; with 1 plumose seta, and comb scales. Gnathopod 2 (Figures 3b, and 21b) subchelate; palm slightly oblique. Basis elongate, more than 3 times longer than wide; posterior margin with 3–5 long setae. Ischium short, subquadrate, shorter than merus. Merus short; posterior margin with 1 seta and distal end of posterior margin with 8 simple setae; posterior inner and outer surfaces with comb scales. Carpus shorter than propodus; anterodistal end with 3 setae; posterior lobe scooplike, elongate, with several submarginal pappose setae and comb scales. Propodus robust, length slightly less than 1.5 times maximum wide, subrectangular; palm slightly shorter than posterior margin; slope slightly irregular, with several long simple setae, and few short and medium setae; distal margin of palm with one truncated process near insertion of dactylus and with one wide posterior excavation at base (Figure 22b); palm posterior distal end with 2 strong setae, comb scales and cup for dactylus. Dactylus claw-like, congruent with palm, without comb scales; outer margin with 1 plumose seta; inner margin crenulate with separated setules. Pereopods 3–7 (Figure 3e–i) simple, gradually longer posteriorly. Pereopod 5 shorter than 4 and 6. Pereopod 3 (Figure 3e), basis elongate; mid-posterior margin with 1–2 simple setae. Merus longer than ischium (almost 3 times the maximum length); anterior margin with 2 setae; posterior margin with 6 setae; anterodistal and posterodistal ends each with one cluster of 4–5 setae, lobe less than one-fourth length of carpus. Carpus shorter and slenderer than merus; posterior margin with 5 stout setae plus accessory setae; posterodistal end with at least 5 slender setae; anterodistal end with at least 2 setae. Propodus shorter than anterior margin of merus, slenderer than carpus; posterior margin with 7 stout setae; anterodistal end with 5 simple setae. Dactylus claw-like, length slightly overreaching half of propodus; nail present. Pereopod 4 (Figure 3f) similar in shape to pereopod 3 but slightly longer; coxa 4 wider than coxa 3 with posterior excavation; basis posterior margin with 1–2 simple setae; merus mid-anterior margin without setae; propodus posterior margin with 6 setae. Pereopods 5–7 (Figure 3g –i) similar in shape; basis posterior lobe rounded and denticulated. Pereopod 7 (Figure 3i) basis lobe widely expanded, almost reaching ischium distal margin; wider than lobes of pereopods 5 and 6; basis lobe, width almost 1.5 times as wide as basis (measured at cleft between basis and basis lobe); posterior margin with 19 serrations, each with 1 setule (17) but 2 serrations with 1 stout seta on distal margin; anterior margin with two clusters of 2 stout setae on distal half and 1 at distal end. Dactylus length almost half of propodus length. Pleopods 1–3 (Figure 4e) not modified, biramous, elongated, rami multi-annulated, with numerous plumose setae; pleopod 1, inner margin of peduncle at distal end with 2 short retinacula (coupling hooks). Uropod 1 (Figure 4a) longer than uropod 2 (Figure 4b); peduncle longer than rami, with 3 dorsal setae, inner and outer distal ends each with 1 seta; rami subequal, inner ramus slightly shorter, with 2 dorsal and 4 distal setae, outer ramus with 3 dorsal and 4 distal setae; male without curved setae on inner ramus. Uropod 2 (Figure 4b) longer than peduncle of uropod 1; peduncle as long as rami, with 2 dorsal setae and 2 additional distal setae; rami subequal, inner ramus slightly longer, with 2–3 dorsal and 4 distal setae, outer ramus with 3 dorsal and 5 distal setae. Uropod 3 (Figures 4c, and 23b) slightly shorter than peduncle of uropod 2; peduncle rectangular, wider than ramus with 5 strong distal setae of variable length; inner ramus absent; outer ramus uniarticulate, slender, slightly shorter than peduncle, 2 times the length of larger seta of peduncle, basal width near 2 times width of apex of ramus, with 3 slender apical setae and 1 connate seta. Telson (Figures 4d, and 24b) entire, as long as wide, distal margin rounded with 2 long simple setae widely separated by almost one-third of maximum width of telson; and two lateral clusters of 3 plumose setae symmetrically distributed. Coxal gills sac-like, present on segments 2–6. Sternal gills tubular, present on segments 3–7. Female (Figure 17b) similar to male. Gnathopod 1 (Figure 3c), ischium distal half of posterior surface with comb scales; carpus with 3 serrate setae on inner face lobe; propodus with 4–5 serrate setae in row over the inner face. Gnathopod 2 (Figure 3d) smaller than male gnathopod 2, parachelated, palm reverse oblique; basis posterior margin with 2–3 setae; ischium distal half of posterior surface with comb scales;propodus slightly longer than twice maximum width, outer face with 3 serrate setae in one row and 3 large setae near palm, anterior and posterior distal half with comb scales. Pereonite 2 with one anterior excavation or notch for amplexus. Pereopod 7 lobe with 13 serrations and setules, and 2 stout setae on distal margin. Oostegites subtriangular with curled setae on margins. Intraspecific variation. Gnathopod 2 of male, basis hind margin up to 5 setae (some organisms from Chalco). Pereopod 3 merus posterior margin up to 4 setae (organisms from Chalco). Habitat. freshwater, epigean, littoral, found associated with roots of Lemna sp. Distribution. Mexico City, Mexico. Remarks Hyalella sarukhani sp. nov. (from Mexico City) can be easily distinguished from species in the Hyalella azteca complex by the telson with rounded distal margin and the presence of 2 long setae wide apart (almost one-third of maximum width of telson). This species has more serrations in the posterior margin of the lobe of pereopod 7 but less stout setae on the distal margin than H. azteca. This species bears setules on the palp of maxilla 1, in contrast with Hyalella wakulla (Drumm and Knight, 2019). The morphological differences from the other Hyalella species described in this work are summarised in Tables S1 and S2 (Table 1)., Published as part of Marrón-Becerra, Aurora & Hermoso-Salazar, Margarita, 2022, Morphological comparison and description of five new species of Hyalella (Crustacea: Amphipoda) from Veracruz and Mexico City, pp. 1215-1263 in Journal of Natural History 56 (25 - 28) on pages 1218-1225, DOI: 10.1080/00222933.2022.2078241, http://zenodo.org/record/7087076

Hyalella alvarezi sp. nov. http://www.zoobank.org/ urn:lsid:zoobank.org:act: 14E267AE-A7D5-4E38-A00A -1CA79136C1FF (Figures 5–7) Etymology. The new species is named in honour of Dr Fernando Alvarez Noguera for his important contribution to carcinological study in Mexico. Material examined. Holotype male, size 4.4 mm (Cat. No. CNCR 35727), from Lake La Encantada in state of Veracruz, Mexico (18.458°N, 95.185°W), 24 July 2015, 332 m a.s.l., temp. 30°C, pH 7. Collectors: A. Marrón-Becerra, E. Lemus-Santana and M. HermosoSalazar. Paratypes (n = 30 males, n = 30 females): males – mean size 4.4 ± 0.5 mm, mean head length 0.6 ± 0.03 mm (n = 27), females – mean size 4.5 ± 0.5 mm, mean head length 0.5 ± 0.04 (n = 25) (permanent slides Cat. No. CNCR 35735, paratypes and SEM preparations CNCR 35736), locality same as holotype. Type locality (Figure 1c). Lake La Encantada, state of Veracruz, Mexico (18.458°N, 95.185°W). Diagnosis. Pleonite 1 and 2 with dorsoposterior carina. Coxa 4 excavated posteriorly. Eyes pigmented. Antenna 1 shorter than antenna 2. Antenna 2 less than half body length. Maxilla 1 palp short, overreaching half of length between base of palp and base of setae in outer plate, with 1 stout distal seta; base of the seta covered by a cylindrical structure, setules present; inner plate slender with 3 strong pappose distal setae. Maxilla 2 inner plate with 2 strong pappose setae on inner margin. Gnathopod 1, propodus hammer shaped, palm slope transverse, inner face with 4 serrate setae, comb scales on distoposterior and distoanterior border, carpus inner lobe with 3–4 serrate setae. Gnathopod 2, basis hind margin with 2 setae and denticles in polygonal pattern. Uropods without curved setae. Uropod 3, peduncle and ramus subequal in length, styliform. Telson as long as wide, distal margin truncated, with 2 long simple apposed setae. Coxal gills on segments 2–6. Sternal gills on segments 3–7. Description of male Body (Figures 5a, and 17c), tergites of pleon 1 and 2 with dorsoposterior carina. Epimeral plates 1–3 slightly acuminate. Coxae 1–3 (Figures 5a, and 17c) subequal in shape, subrectangular, longer than wide, coxa 4 wider than coxae 1–3 with deep posterior excavation, acumination absent. Coxa 5 with two subequal lobes. Coxa 6 anterior lobe reduced, coxa 7 anterior lobe absent. Head typically gammaridean (Figures 5a, and 17c), smaller than first two thoracic segments, rostrum absent. Eyes pigmented, medium, rounded, located between insertions of antennae 1 and 2. Antenna 1 (Figure 5a–b) less than half body length, shorter than antenna 2 (80% length of antenna 2), but longer than peduncle of antenna 2, almost reaching to middle of third pereonite; peduncle longer than head, reaching to middle of length of first pereonite; article 1 and 2 subequal in length, article 1 wider than articles 2–3, article 2 longer and wider than article 3, proportions (1.3:1.26:1), article 1 with 3 short setae ventrally, 1 smaller, and one cluster with 3 cuspidate setae at distal end, articles 1–3 mid-ventral margin with slender setae; flagellum longer than peduncle with 9 articles becoming gradually shorter towards distal portion; aesthetascs on flagellum, present on articles 2–6 (one pair), 7–8 (one). Antenna 2 (Figure 5a, c) almost 1.27 times longer than antenna 1, reaching one-third body length, reaching fourth pereonite; peduncle reaching second pereonite, peduncle articles increase gradually in length and decrease in width; article 3 shorter but wider than 4 and 5, article 4 longer than article 3, article 5 slightly longer than article 4 (almost 1.3 times); flagellum with 8–10 articles, slightly longer than peduncle, without aesthetascs. Buccal parts: upper lip (Figure 5f), distal margin rounded with numerous setules. Lower lip (Figure 5g) subquadrate, outer lobes without notches or excavations, mandibular projection of outer lobes rounded. Mandibles (Figure 5h–i), without palp, asymmetric; incisor toothed, 6 teeth present. Left lacinia mobilis with 5 teeth; setal row on left mandible with 3 main pappose setae plus accessory setae. Right mandible with 5 teeth, right lacinia mobilis reduced, with 2 pairs of asymmetric L-shape teeth; setal row on right mandible with 2 main pappose setae plus accessory setae and with setulae near molar process. Molar process large, cylindrical and triturative, with accessory pappose seta in both molars. Maxilla 1 (Figures 5d, and 19c), palp short, uniarticulate, longer than wide, distally pointed with 1 short distal stout distal seta (A 5 type), with a cylindrical structure near the base that covers almost one-third of distal seta, setules present; palp length slightly exceeds one-half of distance between base of palp and base of seta on outer plate (Figures 5d, and 19c); inner plate slender, shorter than outer plate, with 3 pappose distal setae; outer plate with 9 distal stout serrate setae and with setules. Maxilla 2 (Figure 5e) plates subequal; inner plate shorter and slender with 2 pappose setae on mid-distal inner margin, distal margin with abundant setae and 6 serrulate setae; outer plate without serrate setae but with 2 long pappose setae; outer and inner plates with large simple distal setae (type A2) and abundant setules on both distal surfaces and margins. Maxilliped (Figures 5j, and 20c) inner plate lobe longer than outer plate lobe, distal margin slightly convex, in both plates, inner plate distal margin with 3 cuspidate setae of equal size and with plumose setae, inner margin with several pappose setae; outer plate, inner and distal margins with numerous simple setae. Palp composed of four articles subequal in maximum length, first article with 3 simple setae at inner distal end and without seta on outer distal end; second article with numerous simple setae on inner margin and 3 on the outer distal end; third article with several setae on distal margin, distal end of outer margin with 4 simple setae and comb scales, inner margin with at least 8 setae and at least 5 at distal end; fourth article unguiform slightly longer than nail, with comb scales, inner margin near distal half with 2 setae, and 1 seta near nail base on outer margin; nail exceeds 2/3 of fourth article, with serration at distal half. Gnathopod 1 (Figure 6a) subchelate, hammer shaped. Basis elongated, maximum length almost 3 times longer than maximum width; posterior margin with 1 seta, distal end with one cluster of 2 setae. Ischium short, subquadrate, slightly longer than wide, length almost same as maximum width of basis and maximum length of merus, distal posterior end with one cluster of 4 setae. Merus longer than wide, ventral surface with comb scales, distal margin with 7 setae. Carpus longer than wide, longer than propodus; with strong, short, and wide posterior lobe and forming one scoop-like structure, open to inside; lobe, inner surface with 2–3 serrate setae. Propodus 1.5 times longer than wide, inner surface near distal margin with 3–4 serrate setae (3 in a row), outer surface near half of margin with 1 seta; distal anterior end with two clusters of approximately 8 setae; distal anterior and posterior surfaces with comb scales; palm transverse, posterior distal end with 1 robust seta and cup for dactylus. Dactylus claw-like; nail present; with 1 plumose seta, and comb scales. Gnathopod 2 (Figures 6b, and 21c) subchelate; palm slightly oblique. Basis elongate, more than 3 times longer than wide; posterior margin with 1–2 long setae and denticles in polygonal pattern. Ischium short, subquadrate, shorter than merus. Merus short; posterior margin with 1 seta and distal end of posterior margin with 5 simple setae; posterior inner and outer surfaces with comb scales. Carpus shorter than propodus; anterodistal end with 5 setae; posterior lobe scoop-like, elongate, almost 1.5 times width of merus, with several submarginal pappose setae and comb scales. Propodus robust, almost 1.3 times as long as wide, subrectangular, palm slightly shorter than posterior margin; slope slightly irregular, with several long simple setae, and some short and medium setae; distal margin of palm with one truncated process near insertion of dactylus and with narrow posterior excavation at base (Figure 22c); palm posterior distal end with 2 strong setae, comb scales, and cup for the dactylus. Dactylus claw-like, congruent with palm, without comb scales; outer margin with 1 plumose seta; inner margin with setules widely separated, crenulation absent. Pereopods 3–7 (Figure 6e–i) simple, gradually longer posteriorly; pereopod 5 shorter than 4 and 6. Pereopod 3 (Figure 6e), basis elongate; mid-posterior margin with 1 simple seta. Merus anterior margin with 1 long simple seta; posterior margin with 3 setae; anterodistal and posterodistal end with one cluster of 4 setae. Carpus slightly shorter and slenderer than merus; posterior margin with 4 stout setae plus accessory seta; anterodistal end with at least 5 slender setae, posterodistal end with at least 2 setae. Propodus slenderer than carpus; posterior margin with 4 setae; anterodistal end with 6 simple setae. Dactylus clawlike, length less than half of propodus; nail present. Pereopod 4 (Figure 6f) similar in shape to pereopod 3 but slightly longer, coxa 4 wider than coxa 3 with posterior excavation; basis posterior margin with 1 simple seta; merus mid anterior margin with 1 stout setae; propodus posterior margin with 3–5 setae. Pereopods 5–7 (Figure 6g –i) similar in shape, basis posterior lobe rounded and denticulated; pereopod 7 (Figure 6i) basis lobe widely expanded, almost reaching ischium distal margin; wider than lobes in pereopods 5 and 6; basis lobe width as wide as 1.5 times the basis (measured at cleft between basis and basis lobe); posterior margin with 10–12 serrations, each with 1 setule but 2–4 serrations with 1 stout seta on distal margin; anterior margin with three clusters of 2 stout setae and one cluster of 2 setae at distal end. Dactylus length less than half of propodus length. Pleopods 1–3 (Figure 7e) not modified, biramous, elongated, rami multi-annulated, with numerous plumose setae; pleopod 1, inner margin of peduncle at distal end with 2 short retinacula (coupling hooks). Uropod 1 (Figure 7a) longer than uropod 2 (Figure 7b); peduncle longer than rami, dorsal margin with 2 setae; inner and outer distal ends each with 1 seta; rami subequal, inner ramus slightly longer, with 2 dorsal and 4 distal setae, outer ramus with 2 dorsal and 4 distal setae; male without curved setae on inner ramus. Uropod 2 (Figure 7b) as long as peduncle of uropod 1; peduncle slightly longer than outer rami, with 1 dorsal seta, inner and outer distal ends each with 1 seta; rami subequal; inner ramus slightly longer with 2 dorsal and 3 distal setae; outer ramus with 2 dorsal and 4 distal setae. Uropod 3 (Figures 7c, and 23c) peduncle rectangular, wider than ramus, with 5 strong distal setae of variable length; inner ramus absent; outer ramus uniarticulate, slender, slightly shorter than peduncle, with 4 slender apical setae and 1 connate seta. Telson (Figures 7d, and 24c) entire, as long as wide, distal margin pointed, with 2 long simple setae apposed; two clusters of 3 plumose setae symmetrically distributed. Coxal gills sac-like, present on segments 2–6 (Figure 6h, dotted line). Sternal gills tubular, present on segments 3–7 (Figure 6h, dotted line). Female (Figure 17d) similar to male. Gnathopod 1 (Figure 6c), carpus with 3 serrate setae on the inner face lobe. Propodus with 4 serrate setae in a row over the inner face, and 3 long setae on a row on the outer face. Gnathopod 2 (Figure 6d) smaller than male gnathopod 2, parachelated, palm reverse oblique, basis posterior margin with 1 seta; propodus longer than twice maximum width, outer face with 3–4 serrate setae in a row and 1 large seta near the palm, anterior and posterior distal half with comb scales. Pereonite 2 with one anterior excavation or notch for amplexus. Pereopod 7 lobes with 9 serrations and setules, and with 2 stout setae on the distal margin. Oostegites subtriangular, almost reaching one-half length of merus, with setae curled on the margins. Intraspecific variation. The palp of maxilla 1 is short and varies in length and form in the same organism or if is moulting; can reach a maximum length of almost 2 times width and presents constricted margin in the middle. Habitat. Freshwater, epigean, littoral, associated with Eichhornia crassipes (Mart.) Solms. Distribution. Lake La Encantada, state of Veracruz, Mexico (18.458°N, 95.185°W). Remarks Hyalella alvarezi sp. nov. (La Encantada, Veracruz) shares morphological traits with the other species from Veracruz and with H. wakulla from Florida, such as the dorsal mucronations (except in H. garyi sp. nov.), and the telson with 2 distal setae apposed, similar to H. azteca s.s. (except in H. sarukhani sp. nov., and H. garyi sp. nov.). This species can be distinguished primarily by the presence of one cylindrical base covering almost one-third of the distal setae in palp of maxilla 1, the polygonal pattern (denticles) over the surface of basis in male gnathopod 2 (similar to H. gauchensis Streck and Castiglioni, 2017, H. georginae Streck and Castiglioni, 2017 and H. rioantensis Penoni and Bueno, 2020 – i.e. the three from southern Brazil), and one slender excavation in the palm of male gnathopod 2. On the other hand, this species shares morphological characters with H. sarukhani sp. nov. (Tables 1, S1–S 2)., Published as part of Marrón-Becerra, Aurora & Hermoso-Salazar, Margarita, 2022, Morphological comparison and description of five new species of Hyalella (Crustacea: Amphipoda) from Veracruz and Mexico City, pp. 1215-1263 in Journal of Natural History 56 (25 - 28) on pages 1225-1232, DOI: 10.1080/00222933.2022.2078241, http://zenodo.org/record/7087076

Hyalella garyi sp. nov. http://www.zoobank.org/ urn:lsid:zoobank.org:act: 3B63AA3A-852D-4852-92C0- 4829136EEE1E (Figures 14–16) Etymology. The new species is named in honour of Dr Gary A. Wellbon for his valuable contributions to the knowledge of the Hyalella genus. Material examined. Holotype male, size 4.7 mm (Cat. No. CNCR 35730), from Lake Catemaco, state of Veracruz, Mexico (18.366°N, 95.084°W), 24 July 2015, 335 m a.s.l., temp. 34°C, pH 7. Collectors: A. Marrón-Becerra, E. Lemus-Santana and M. HermosoSalazar. Paratypes (n = 30 males, n = 30 females): males – mean size 4.8 ± 0.6 mm, mean head length 0.5 ± 0.1 mm (n = 27), females – mean size 4.5 ± 0.2 mm, mean head length 0.5 ± 0.06 (n = 27) (permanent slides Cat. No. CNCR 35741, paratypes and SEM preparations CNCR 35742), locality same as holotype. Type locality (Figure 1). Lake Catemaco, state of Veracruz, Mexico (18.366°N, 95.084°W). Diagnosis. Pleonite 1 and 2 without dorsoposterior carina. Coxa 4 excavated posteriorly. Eyes pigmented. Antenna 1 shorter than antenna 2. Antenna 2 less than half body length. Maxilla 1 palp short, reaching less than half of length between base of palp and base of setae in outer plate, without distal seta, setules present; inner plate slender with 3 strong pappose distal setae. Maxilla 2 inner plate with 2 strong pappose setae on inner margin. Gnathopod 1, propodus hammer shaped, palm slope transverse, inner face with 3 serrate setae, comb scales on distoposterior and distoanterior border, carpus inner face lobe with 3 serrate setae. Gnathopod 2, basis hind margin without setae. Uropods without curved setae. Uropod 3, peduncle and ramus subequal in length, styliform. Telson as long as wide, distal margin pointed or truncated, with 2 long simple apposed setae. Coxal gills on segments 2–6. Sternal gills on segments 3–7. Description of male Body (Figures 14a, and 18c, e), tergites of pleon 1 and 2 without dorsoposterior carina. Epimeral plates 1–3 slightly acuminate. Coxae 1–3 (Figures 14a, and 18c) subequal in shape, subrectangular, longer than wide; coxa 4 wider than coxae 1–3 with deep posterior excavation; acumination absent. Coxa 5 with two subequal lobes, anterior lobe slightly shorter than posterior, anterior lobe reduced; coxa 7 anterior lobe absent. Head typically gammaridean (Figures 14a, and 18c), shorter than length of first two thoracic segments, rostrum absent. Eyes pigmented, medium, rounded, located between insertions of antennae 1 and 2. Antenna 1 (Figure 14a–b) less than half body length, shorter than antenna 2, but longer than peduncle of antenna 2, almost reaching to middle of third pereonite; peduncle longer than head, reaching half the length of first pereonite; articles 1 and 2 subequal in length, article 1 wider than articles 2–3, article 2 longer and wider than article 3 (1.1:1.2:1), article 1 with 3 short setae ventrally, 1 smaller, and one cluster with 3 cuspidate setae at distal end, articles 1–3 mid-ventral margin with slender setae; flagellum slightly longer than peduncle with 8–9 articles gradually shorter towards distal portion; aesthetascs present on articles 2–6 (one pair), 7–8 (one). Antenna 2 (Figure 14a, c) almost 1.27 times longer than antenna 1, reaching one-third body length, reaching the fourth pereonite; peduncle articles increase gradually in length and decrease in width; article 3 shorter but wider than 4 and 5, article 4 longer than article 3, article 5 slightly longer than article 4; flagellum with 8–10 articles, slightly longer than peduncle; without aesthetascs. Buccal parts: upper lip (Figure 14f), distal margin rounded with numerous setules. Lower lip (Figure 14g) subquadrate, outer lobes without notches or excavations, mandibular projection of outer lobes rounded. Mandibles (Figure 14h–i) without palp, asymmetric. Incisor toothed, 6 teeth present. Left lacinia mobilis with 5 teeth; setal row on left mandible with 3 main pappose setae plus accessory setae. Right mandible with 6 teeth, right lacinia mobilis more reduced than left, with 2 pairs of asymmetric L-shaped teeth; setal row on right mandible with 2 main pappose setae plus accessory setae and with setulae near the molar process. Both molar processes large, cylindrical and triturative, with accessory pappose setae. Maxilla 1 (Figures 14d, and 19f), palp short, vestigial, uniarticulate, longer than wide, distally rounded, setules present, without stout distal seta (A 5 type); palp length no more than one-third of distance between base of palp and base of setae on outer plate; inner plate slender, shorter than outer plate, with 3 pappose distal setae (2 distal and 1–2 subdistal); outer plate with 9 distal stout serrate setae and with setules. Maxilla 2 (Figure 14e) plates subequal; inner plate shorter and slender, with 2 pappose setae on mid-distal inner margin, without serrulate setae on distal margin; outer plate without serrulate setae but with 2 long pappose setae; outer and inner plates with large simple setae (A 2 type), and setules on both distal surfaces and margins. Maxilliped (Figures 14j, and 20f) inner plate lobe longer than outer plate lobe; distal margin slightly convex; inner plate distal margin with 3 cuspidate setae of equal size and with plumose setae; inner margin with several pappose setae; outer plate, inner and distal margins with numerous simple setae. Palp composed of four articles subequal in maximum length; first article with 6 simple setae at inner distal end and 1 seta at outer distal end; second article with numerous simple setae on inner margin and 1 on outer distal end; third article with several long simple setae, distal end of outer margin with 1 simple seta and comb scales, inner margin with 5 setae and 5 at distal end; fourth article unguiform, slightly longer than the nail, with comb scales, inner margin near distal half with 4 setae and 2 near nail base on outer margin; nail exceeds 2/3 of fourth article, with serration at distal half. Gnathopod 1 (Figure 15a) subchelate, hammer shaped. Basis elongated, maximum length almost 3 times longer than maximum width; posterior margin without seta, distal end without cluster of setae. Ischium short, subquadrate; distal posterior end with one cluster of 2 setae. Merus longer than wide, ventral surface with comb scales; distal margin with 8 setae. Carpus longer than wide, longer than propodus; with strong, short, and wide posterior lobe forming one scoop-like structure open to inside; inner surface with 3 serrate setae. Propodus less than 1.5 times longer than wide, anterior margin distal third with 1 medial seta; inner surface with 3 serrate setae in one row, outer surface with 1 seta on margin near halfway point; distal anterior end with two clusters of approximately 8 setae; distal anterior and posterior surfaces with comb scales; palm transverse, posterior distal end with 1 robust seta and cup for dactylus. Dactylus claw-like; nail present; anterior surface near proximal third with 1 plumose seta, with comb scales over anterior surface. Gnathopod 2 (Figures 15b, and 21f) subchelated; palm slightly oblique. Basis elongate, more than 3 times longer than wide; posterior margin without seta. Ischium short, subquadrate, shorter than merus. Merus short; posterior margin with 8 simple setae, posterior inner and outer surfaces with comb scales. Carpus shorter than propodus; anterodistal end with 6 setae; posterior lobe scoop-like, elongate, length similar to merus maximum length, almost 1.5 times width of merus, with several submarginal pappose setae and comb scales. Propodus robust, length almost 1.5 times as long as wide, subrectangular; palm similar in length to slightly longer than posterior margin; slope slightly irregular, with several long simple setae, and some short and medium setae; distal margin of palm with one truncated process near insertion of dactylus, and with wide posterior excavation (Figure 22f); palm posterior distal end with 2 strong setae, comb scales and cup for the dactylus. Dactylus claw-like, congruent with palm, without comb scales; outer margin with 1 plumose seta; inner margin crenulate with setules. Pereopods 3–7 (Figure 15e–i) simple, gradually longer posteriorly, pereopod 5 slightly shorter than 4 and 6. Pereopod 3 (Figure 15e), basis elongate; mid-posterior margin without simple seta. Merus anterior margin with 1 stout seta, posterior margin with 2 long simple setae respectively and 1 medial shorter seta; anterodistal and posterodistal ends with one cluster of 4 and 7 setae, respectively. Carpus slightly shorter and slenderer than merus; posterior margin with 2 stout setae plus accessory seta; posterodistal end with at least 7 slender setae; anterodistal end with at least 6 setae. Propodus slenderer than carpus; posterior margin with 3 setae; anterodistal end with 5 simple setae. Dactylus claw-like, length almost half of propodus; nail present. Pereopod 4 (Figure 15f) similar in shape to pereopod 3 but slightly longer; coxa 4 wider than 3 with posterior excavation; basis posterior margin without simple seta; merus midanterior margin without setae; propodus posterior margin with 4 stout setae. Pereopods 5–7 (Figure 15g –i) similar in shape; basis posterior lobe rounded and denticulated. Pereopod 7 (Figure 15i) basis lobe widely expanded, almost reaching ischium distal margin; basis lobe, width 1.6 times as width as basis (measured at cleft between basis and basis lobe); posterior margin with 8 serrations, each with 1 setule without stout seta on distal margin; anterior margin with 2 stout setae and one cluster of 2 setae at distal end. Dactylus length less than half of propodus length. Pleopods 1–3 (Figure 16e) not modified, biramous, elongated, rami multi-annulated, with numerous plumose setae; pleopod 1, inner margin of peduncle at distal end with 2 short retinacula (coupling hooks) at distal end. Uropod 1 (Figure 16a) longer than uropod 2; peduncle longer than rami, with 2 dorsal setae, inner and outer distal ends each with 1 seta; rami subequal, inner ramus slightly longer, with 2 dorsal and 4 distal setae, outer ramus with 2 dorsal and 4 distal setae; male without curved setae on inner ramus. Uropod 2 (Figure 16b) as long as peduncle of uropod 1; peduncle shorter than outer rami, with 1 dorsal seta and 1 seta at distal end; rami subequal, inner ramus slightly longer with 2 dorsal and 4 distal setae, outer ramus with 2 dorsal and 3 distal setae. Uropod 3 (Figures 16c, and 23f) slightly shorter than peduncle of uropod 2; peduncle rectangular, wider than ramus with 3 strong distal setae of variable length; inner ramus absent; outer ramus uniarticulate, slender, slightly shorter than peduncle, 2 times length of larger seta of peduncle, basal width almost 2 times width of apex of ramus, with 3 slender apical setae (1 longer) and 1 connate seta. Telson (Figures 16d, and 24f) entire, longer than wide, distal margin rounded, with 2 long simple apposed or separated setae; with two clusters of 3 plumose setae near middle distal portion, near margin, symmetrically distributed. Coxal gills sac-like,present on segments 2–6. Sternal gills tubular, present on segments 3–7. Female (Figure 18d) similar to male. Gnathopod 1 (Figure 15c), carpus with 7 serrate setae on the inner face lobe. Gnathopod 2 (Figure 15d) smaller than male gnathopod 2, parachelated, palm reverse oblique, basis posterior margin without seta; propodus longer than twice maximum width, inner face with 3 serrate setae in a row, outer face with 3 setae in a row and 3 large setae near the palm, anterior and posterior distal half with comb scales. Pereonite 2 with one anterior excavation or notch for amplexus. Pereopod 7 lobes with 10–13 serrations and setules, and without stout setae on the distal margin. Oostegites subtriangular with setae curled on the margins. Habitat. Freshwater, epigean, littoral, associated with sediment and Eichhornia crassipes (Mart.) Solms. Distribution. Lake Catemaco, state of Veracruz, Mexico (18.366°N, 95.084°W). Remarks This species is similar to H. villalobosi sp. nov.; however, H. garyi sp. nov. can be distinguished by the absence of dorsal mucronations on the pleon, the shape of the upper lip (subquadrate), the shape of the lower lip (subtriangular in H. villalobosi sp. nov.), the absence of 1 distal seta in the palp of maxilla 1 (similar to H. azteca s.s.) but with setules (absent in H. wakulla Drumm and Knight-Gray, 2019), the inner plate of maxilla 2 wider, the absence of setae in the hind margin of male gnathopod 2, the length of the merus vs isquium in the pereiopod 3 (close to 2 times), the relative witdth of the base of uropod 3 (less than 2 times), and the distal margin of telson rounded, in contrast to the other species from Veracruz with the margin acute (similar to H. azteca s.s.). In the species from lake Catemaco (H. villalobosi sp. nov. and H. garyi sp. nov.) the articles of the palp in maxilliped are apparently longer than articles in H. azteca and the other species described herein., Published as part of Marrón-Becerra, Aurora & Hermoso-Salazar, Margarita, 2022, Morphological comparison and description of five new species of Hyalella (Crustacea: Amphipoda) from Veracruz and Mexico City, pp. 1215-1263 in Journal of Natural History 56 (25 - 28) on pages 1245-1253, DOI: 10.1080/00222933.2022.2078241, http://zenodo.org/record/7087076, {"references":["Drumm DT, Knight-Gray J. 2019. A new species of the Hyalella ' azteca ' complex (Crustacea: Amphipoda: Hyalellidae) from Florida. Zootaxa. 4545 (1): 93 - 104. doi: 10.11646 / zootaxa. 4545.1.5"]}

Hyalella luciae n. sp. Limberger, Santos and Castiglioni (Figs. 1A e 1B) Type material: Site 1— Holotype, male, body length = 8.69 mm, head length = 0.92 mm, Brazil, municipality of São Pedro das Missões, state of Rio Grande do Sul (27°46’45.8”S- 53°15’37.2”W), December, 05, 2014. Streck-Marx M. T. & Castiglioni, D.S. cols., MNRJ 30141 (Fig. 1A). Allotype, females, body length = 7.30 mm, head length = 0.75 mm, Brazil, municipality of São Pedro das Missões, state of Rio Grande do Sul (27°46’45.8”S- 53°15’37.2”W), December 05, 2014. Streck-Marx, M. T. & Castiglioni, D.S. cols., MNRJ 30142 (Fig. 1B). Paratypes (same data and collectors of the holotype): five males and five females, MNRJ 30143. Paratypes (Laboratório de Taxonomia Animal) (same data and collector of the holotype): 61 males, 67 females and 18 ovigerous females wholes and five males and two females in slides, CLZE 45. Type locality. Brazil, state of Rio Grande do Sul, municipality of São Pedro das Missões, small spring (27°46’45.8”S- 53°15’37.2”W) (Várzea River Basin), 535 meters of altitude (Fig. 2A)., Published as part of Limberger, Márcio, Santos, Sandro & Castiglioni, Daniela Da Silva, 2022, Hyalella luciae (Crustacea, Amphipoda, Hyalellidae) - a new species of freshwater amphipod from Southern Brazil, pp. 568-582 in Zootaxa 5174 (5) on pages 569-570, DOI: 10.11646/zootaxa.5174.5.5, http://zenodo.org/record/6994036

Lake Titicaca, in the High Andes of Perú and Bolivia, harbours the world’s third most speciose ancient-lake amphipod radiation on record. A minimum of nineteen species of Hyalella derived from at least five independent colonization episodes concentrate in this high altitude water body, although the actual species number present has not yet been established and could be much higher. Herein, we take advantage of the description of three new species (H. krolli, H. gonzalezi, and H. hirsuta) and the re-description of other two (H. solida and H. nefrens) to assess the feasibility of adopting a dna-based identification approach to resolve the magnitude of this highly speciose amphipod assemblage. A Bayesian phylogenetic analysis of the evolutionary relationships among South American Hyalella cox1 haplotypes, including those of four out of the five species dealt with herein, shows a great disagreement between taxonomic units delimited under morphological and genetic data, hampering species identification exclusively based on cox1 dna barcode sequences., This work was supported by the Spanish Agencia Española de Investigación, (aei) and the European Regional Development Fund (feder) under Grant cgl2016-76164-P. Francesco Zapelloni benefited from grant bes-2017–081069 of the Spanish Ministerio de Ciencia, Innovación y Universidades.

The exposure to environmentally relevant chlorpyrifos concentrations (0.03, 0.06 and 0.12 µg chlorpyrifos L−1) causes increases in precopulatory guardian behavior time, amplexus reformulation after exposure and in the number of ovigerous females in the amphipod Hyalella curvispina. Effects in incubation period, effective hatching and median lethal concentration on the decapods Macrobrachium borellii and Aegla uruguayana, both in adults and embryos, were achieved at higher concentrations than those found in the environment. Environmentally relevant chlorpyrifos concentrations appear not to affect decapods but several effects in reproductive traits of amphipods were observed.

Since its description, the troglobitic amphipod Hyalella veredae Cardoso & Bueno, 2014 has been recorded only in its type locality, Vereda da Palha cave, in southeastern Brazil. We report this species from three other caves in the region, expanding its distribution by at least 20 km². Inter- and intra-population variability in eye size was observed. Two caves had larger populations, probably due to the presence of biofilm. The species was classified as Critically Endangered due to its restricted area of occurrence, and regional impacts and threats.

Resumen Introducción: Los arroyos asociados a bofedales se hallan en ambientes donde las condiciones son extremas con temperaturas muy variables, baja presión atmosférica e intensa radiación solar. Sin embargo, existen ensamblajes de macroinvertebrados asociados a estos ambientes, cuya información es escasa. A escala global y regional, las características de los macroinvertebrados cambian con el aumento de la latitud y altitud (disminución de la riqueza y variación de la composición). A nivel local, también se puede agregar el efecto de las aguas ácidas y de elevada conductividad proveniente de manantiales que se unen a los arroyos, que generan heterogeneidad en la calidad de agua y consecuentemente en las características de los macroinvertebrados. Objetivo: Comparar la diversidad, composición y abundancia de macroinvertebrados y las características fisicoquímicas del agua de arroyos asociados a dos bofedales altoandinos, ubicados en el departamento de Ayacucho, Perú. Metodología: Se estudiaron once estaciones ubicados en arroyos de dos bofedales: 7 en Guitarrachayocc (G) de 43 ha (n = 28) y 4 en Pichccahuasi (P) de 28 ha (n = 8). Se empleó una red de Surber (0.3 mm de malla, área de muestreo de 1 200 cm2), para realizar muestreos mensuales de octubre de 2016 a abril de 2017. Análisis de componentes principales (PCA) y análisis de varianza multivariante no paramétrico (NP-MANOVA) se aplicaron para comparar las características del agua. Además, se utilizó un análisis de coordenadas principales (PCoA) y NP-MANOVA para comparar el ensamblaje. La prueba no paramétrica de Kruskal-Wallis (α = 0.05) se utilizó para comparar las abundancias absolutas de los taxa principales. Resultados: Las características del agua fueron heterogéneas, con pH de 3.2 (± 0.4) a 7.6 (± 0.1), conductividad de 168.9 (± 91) µS/cm a 1 117 (± 159.3) µS/cm; diferencias que fueron significativas (p < 0.05) al comparar las estaciones de muestreo, donde el agua de G6 presenta los mínimos valores de pH y los máximos de conductividad, al igual que cloruros. Se recolectaron un total de 8 126 individuos, distribuidos en 26 taxa de 20 familias, 11 órdenes y cinco clases. Los insectos fueron el grupo más diverso y abundante. A pesar a la cercanía de los arroyos de los bofedales, presentaron diferencias: en G, se registró 25 taxa, con dominancia de Macrelmis sp., Dicrotendipes sp., Claudioperla sp., Meridialaris sp. y en P, 9, con dominancia de Pedrowygomya sp., Hyalella sp. y Dicrotendipes sp. La densidad fue de 475 ind./m2 y de 31 ind./m2 para el bofedal G y P respectivamente, estos valores fueron estadísticamente diferentes (p < 0.05). El PCoA y el PCA confirmados por NP-MANOVA mostraron que G6 es diferente (p < 0.05) dentro de G porque recibe el aporte de agua de un manantial. Conclusiones: La riqueza, composición y densidad de los macroinvertebrados son diferentes en los arroyos según el bofedal al cual se halla asociado. La contribución de los manantiales a los arroyos genera cambios drásticos en la calidad del agua y los macroinvertebrados, determinando la formación de ensamblajes con diferente riqueza y estructura. Abstract Introduction: Streams associated with high Andean wetlands are found in environments where conditions are extreme, highly variable temperature, low atmospheric pressure, intense solar radiation. The macroinvertebrate assemblages have been poorly studied compared to streams located at lower altitudes. On a global and regional scale, the characteristics of macroinvertebrates change with the increase in latitude and altitude (decreasing in richness and variation in composition). At the local level, the effect of acidic waters with high conductivity from springs that join streams generate heterogeneity in water quality and consequently in the characteristics of macroinvertebrate structure. Objective: To compare the diversity, composition and abundance of macroinvertebrates and the physicochemical characteristics of stream water in two high Andean wetlands in Peru. Methodology: Eleven stations located in streams of two high Andean wetlands were studied: 7 in Guitarrachayocc (G) of 43 ha (n = 28) and 4 in Pichccahuasi (P) of 28 ha (n = 8). A Surber sampler (0.3 mm mesh, sampling area of 1 200 cm2) was used to carry out monthly samplings from October 2016 to April 2017. Principal Component Analysis (PCA) and Non-Parametric-Multivariate-Analysis-Of-Variance (NP-MANOVA) were applied to compare water characteristics. The macroinvertebrate assemblages from the two streams were compared by using a Principal coordinate analysis (PCoA), NP-MANOVA, and a non-parametric Kruskal-Wallis test (α = 0.05). Results: The characteristics of the water were heterogeneous, with significant differences in pH which ranged from 3.2 (± 0.4) to 7.6 (± 0.1) and conductivity ranging from 168.9 (± 91.0) µS / cm to 1 117.0 (± 159.3) µS / cm. In particular, G6 presented the lowest pH values and the highest electrical conductivity, as well as chlorides. A total of 8 126 individuals were collected, distributed in 26 taxa from 20 families, 11 orders and five classes. Insects were the most diverse and abundant group. Differences were found between the streams of the highland wetlands, despite their proximity: in G, 25 taxa were registered, with a dominance of Macrelmis sp., Dicrotendipes sp., Claudioperla sp. and Meridialaris sp. and in P, 9, with a dominance of Pedrowygomya sp., Hyalella sp. and Dicrotendipes sp. The density was 475 ind./m2 and 31 ind./m2 for G and P respectively, these values were statistically different (p < 0.05). The PCoA and PCA confirmed by NP-MANOVA showed that G6 was different (p < 0.05) within G because it receives water contribution from a spring. Conclusions: The richness, composition and density of macroinvertebrates were different in streams depending on the bofedal with which it is associated. The contribution of the springs to the streams generates drastic changes in the quality of the water and the macroinvertebrates, determining the formation of assemblages with different richness and structure.

Despite being remote, polar and sub-polar regions are increasingly threatened by global ecological change. For instance, South America’s sub-Antarctic forest ecoregion is considered one of the world’s last wilderness areas and a global reference site for pre-Industrial Revolution nutrient cycles. Nonetheless, the North American beaver (Castor canadensis) was introduced to Tierra del Fuego in 1946 and, as an invasive ecosystem engineer, has transformed the ecology of regional watersheds. Beavers’ engineering activities transform forested streams (FS) into beaver ponds (BP), where there is greater light and primary production (allochthonous organic matter) and, consequently, increased basal resource quality. To investigate this, we analyzed algal, diatom, fungal and bacterial fatty acid (FA) biomarkers in three basal resource categories (biofilm, very fine benthic organic matter, coarse benthic organic matter) and benthic consumers from four functional feeding groups (FFG). The amphipod Hyalella spp. was chosen as an indicator species due to its abundance and biomass in both habitats. Hyalella spp. had higher proportions of algal and bacterial FA in BP than FS. In FS, Hyalella spp. (gatherer) and Gigantodax spp. (filterer, Diptera) had greater contributions of higher quality FA (higher in polyunsaturated FA), while Rheochorema magallanicum (predator, Trichoptera) and Meridialaris spp. (scraper, Ephemeroptera) showed lower quality monounsaturated and saturated FA. All FFGs showed evidence of microbial FA and had higher levels of autochthonous FA biomarkers than their food resources. Scrapers had the greatest proportion of autochthonous FA. These data provide new insights into the utilization of basal resources by stream consumers in sub-Antarctic streams and how beavers modify these ecosystems. Fil: Anderson, Christopher Brian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur. Instituto de Ciencias Polares, Ambientales y Recursos Naturales; Argentina Fil: Tagliaferro, Marina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Fisk, Aaron. University of Guelph; Canadá Fil: Rosemond, Amy D.. University of Georgia; Estados Unidos Fil: Sanchez, Marisol. University of North Texas; Estados Unidos Fil: Arts, Michael T.. Ryerson University; Canadá

Regulatory assessment of the bioaccumulation from water is commonly based on bioconcentration factors (BCFs) derived from fish flow-through tests. Such experiments require many laboratory animals and are time-consuming and costly. An alternative test setup for organic, neutral compounds using the amphipod Hyalella azteca was recently suggested, resulting in BCF values which show a strong correlation with fish BCF data. In the present study, the bioconcentration potential of the ionic compound laurate was elucidated in H. azteca. The sodium salt of 1-14 C laurate was applied to H. azteca in a flow-through and a semistatic approach. Because of rapid biodegradation, a semistatic approach with frequent medium replacements was required to ensure a stable medium concentration. Laurate was also rapidly metabolized by H. azteca. A large proportion of the total radioactivity measured in the amphipod tissue was not extractable, suggesting that mineralized laurate was accumulated in the calcified exoskeleton of H. azteca. This was confirmed in a further study using carbonate [14 C]. A lipid-normalized (5.0%) Hyalella BCF of 8.9 was calculated for laurate, measured as free fatty acids. The results of the bioconcentration studies with H. azteca confirm the low bioaccumulation potential of the test item previously observed in fish. However, more organic ionic compounds with various properties need to be tested to assess whether a general correlation between fish and Hyalella BCF data exists. Environ Toxicol Chem 2020;39:310-322. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Hyalella insulae Rangel, Limberger & Castiglioni, n. sp. (Figs. 3–8) Type material. MNRJ 30138 — Holotype male. Body length = 5.87 mm, head length = 0.62 mm, Cachoeira Grande, Monumento Natural Municipal da Lagoa do Peri, municipality of Florianópolis, Santa Catarina Island, state of Santa Catarina, Brazil (48°32’22”W, 27°43’55.00”S), 27 August 2010, Lisboa, Lemos & Siegloch cols. MNRJ 30139 — Allotype female. Body length = 4.26 mm, head length = 0.45 mm, with the same place and data as holotype. MNRJ 30140— Paratypes (3 males and 3 females), with the same place and data as holotype. Measurements from paratypes: males—mean body length 5.33 ± 0.599 mm, mean head length 0.56 ± 0.06 mm; females—mean body length 4.86 ± 0.76 mm, mean head length 0.51 ± 0 0.08 mm. UFSM 100—Site 1— Paratypes: 7 males and 13 females (being two ovigerous females wholes; 5 males and 2 females in slides), with the same place and data as holotype. Other material: UFSM 101 — Ribeirão Grande, Sertão do Peri, Monumento Natural Municipal da Lagoa do Peri, municipality of Florianópolis, Santa Catarina Island, state of Santa Catarina, Brazil (48º32’03’W, 27º44’08”S), 28 May 2010, Coelho & Siegloch cols., 2 males and 4 females. Type locality. Brazil, state of Santa Catarina, municipality of Florianópolis, Santa Catarina Island, locality of Monumento Natural Municipal da Lagoa do Peri, Cachoeira Grande stream (48°32’22”W, 27°43’55.00”S), 27 August 2010 (Fig. 2). Diagnosis. Body surface smooth. Epimeral plates not acuminated. Eyes pigmented. Antenna 1 shorter than antenna 2. Mandible incisor toothed. Maxilla 1 palp short, longer than wider, reaching less than half length the distance between base of palp and tip of setae on outer plate; inner plate slender, with two papposerrate apical setae; outer plate with nine serrate setae apically. Maxilla 2 inner margin of inner plate with two papposerrate setae, being one longer. Propodus of gnathopod 1 hammer-shaped, inner face with seven serrate setae, denticles as comb scales on disto-anterior and disto-posterior margins, posterior lobe of carpus with pectinate border. Gnathopod 2 propodus ovate, elongated, irregular palm, disto-posterior margin with denticles as comb-scales, posterior lobe of carpus with pectinate border. Uropod 1 male inner ramus with curved seta. Uropod 3 peduncle with ten cuspidate setae with accessory setae, ramus with eight simple setae and one cuspidate seta. Telson apically rounded, with six cuspidate setae with accessory setae. Sternal gills on segments 2 to 7. Description of males paratypes. (Figure 3A). Mean body length: 5.87 ± 0.74 (N = 10), minimum body length = 4.70 mm, maximum body length = 6.81 mm; mean head length: 0.62 mm ± 0.09 mm (N = 10), minimum head length = 0.50 mm, maximum head length = 0.72 mm. Body surface smooth. Epimeral plates not acuminated. Head smaller than first two thoracic segments. Eyes round and pigmented. Antenna 1 less than half of body length, shorter than antenna 2, longer than peduncle of antenna 2, peduncle shorter than head; flagellum with 11–12 articles, longer than peduncle, basal article not elongated; aesthetascs on flagellum on articles 5 (2), 6 (2), 7 (2), 8 (2) and 9 (2) distally (Fig. 4B). Antenna 2 less than half of body length; peduncle with similar size of the head; flagellum with 14 to 15 articles (Fig. 4C) Basic amphipodan mandible (in the sense of Watling 1993) without palp; incisor toothed; left lacinia mobilis with five teeth, setae row with three pappose setae, molar process large, cylindrical, with large accessory setae; right mandible with three pappose setae (one shorter), molar large, cylindrical, triturative with accessory seta (Fig. 4D). Upper-lip margin rounded, distal margin covered by several short setules on ventral and dorsal faces (Fig. 4E). Lower-lip lobes rounded without notches or excavations, with several small setules on dorsal and ventral faces (Fig. 4F). Maxilla 1 palp uniarticulate, longer than wider, short, reaching less than half length the distance between base of palp and tip of setae on outer plate, inner plate slender, smaller than outer plate, with two papposerrate apical setae and margin with several simple setae; outer plate with nine serrate setae (Fig. 4G). Maxilla 2 inner plate wider than outer plate and with two papposerrate setae (being one longer), 10 pappose setae, several simple setae apically, and several setules distally; outer plate apex with abundant long simple setae (Fig. 4H). Maxilliped inner plates apically rounded, with three strong cuspidate distal setae, five serrate setae and five pappose setae; outer plate larger than inner plate, apically rounded, apical, medial and facial with simple setae; palp longer than outer plate, with four articles, margin with several simple setae; dactylus unguiform, smaller than third article, with simple setae and distal nail (Fig. 4I). Gnathopod 1 subchelate; basis, ischium and merus with simple setae; carpus longer than wide, as long as propodus, with strong and wide posterior lobe, margin with polygonal pattern (border pectinate), one row of denticles as comb-scales and one row of serrate setae, ten serrate setae on ventral face; propodus length about 1.5 times maximum width (rectangular), hammer shape, inner face with seven serrate setae and five short simple setae and some triangular setae, disto-posterior border with two cuspidate setae, denticles as comb-scales and three simple setae, antero-posterior border with comb-scales and cluster of simple setae, mid-anterior margin with two simple setae; dactylus claw-like not surpassing the palm, with denticles as comb scales, one plumose seta dorsally (Fig. 5A). Gnathopod 2 subchelate; basis (long), ischium and merus with cluster of simple setae on disto-posterior border; carpus wider than long, narrow posterior lobe, margin elongated with border pectinate, one row of serrate setae and one row of denticles as comb scales; propodus ovate (length 1.2 maximum width), palm shorter than posterior margin, slope oblique, palm with irregular margin with several long and short cuspidate setae with accessory setae and some simple setae, disto-posterior margin with denticles as comb scales, two short and strong cuspidate setae with accessory setae and some simple setae, anterior margin with one simple setae, disto-anterior margin with two cluster of simple setae; dactylus claw-like, shorter than propodus, with one one plumose seta dorsally (Fig. 5B). Peraeopods 3 to 7 simple; merus, carpus and propodus posterior margins with clusters of 2–3 cuspidate setae with accessory setae, cluster of simple setae on anterior and posterior borders; peraeopods 3 to 7 dactylus less than half-length of propodus; peraeopods 3 to 6 with similar size and peraeopod 7 slightly longer; coxal plates of peraeopod 3, 5, 6 and 7 wider than longer, with small simple setae on margin; peraeopod 4 coxal plate excavated posteriorly and slightly wider than longer (Fig. 6A–E). Pleopods not modified and all similar in shape; peduncle slender; ramus longer than peduncle, with two coupling setae (Fig. 7A). Uropod 1 longer than uropod 2; peduncle longer than ramus, seven cuspidate setae with accessory setae on dorsal surface; inner ramus slightly longer than outer ramus with three cuspidate setae with accessory setae and one curved seta on lateral margin, apex with five cuspidate setae with accessory setae and two strong cuspidate setae; outer ramus with four dorsal cuspidate setae with accessory setae and four distal cuspidate setae (two with accessory setae) (Fig. 7B). Uropod 2 peduncle longer than wide, similar size of ramus with five cuspidate setae with accessory setae; inner ramus with three dorsal cuspidate setae with accessory seta and six distal cuspidate setae (four with accessory setae); outer ramus with four dorsal and four distal setae (two with accessory setae) (Fig. 7C). Uropod 3 peduncle rectangular and slightly longer than ramus, with ten strong cuspidate setae with accessory setae, outer margin with one simple seta and three simple setae on basis; inner ramus absent; outer ramus uniarticulate with eight simple setae (some longer than others) and one small cuspidate seta (Fig. 7D). Telson wider than long, apically rounded, with six cuspidate setae with accessory setae and two small plumose setae laterally close to each distal seta (Fig. 7E). Coxal gills sac-like, on segments 2 to 6. Sternal gills tubular, on segments 2 to 7. Description of paratypes females (Figure 3B): Mean body length: 4.60 ± 0.36 (N = 10), minimum body length = 4.23 mm, maximum body length = 5.17 mm; mean head length: 0.49 mm ± 0.04 mm (N = 10), minimum head length = 0.45 mm, maximum head length = 0.55 mm. Antenna 1 shorter than Antenna 2. Antenna 1 flagellum with nine to ten articles. Antenna 2 similar in shape to male, flagellum with eleven to twelve articles. Gnathopod 1 slightly wider than gnathopod 2; similar to male gnathopod 1 in size and shape; basis, ischium and merus without comb-scales; carpus with pectinate lobe with comb-scales and several serrate setae, four serrate setae on ventral face; propodus inner face with seven serrate setae, simple setae on the inner margin, disto-anterior border with comb-scales, disto-posterior border without comb-scales but with a cluster of simple setae; dactylus claw-like with one plumose setae and with comb-scales (Fig. 8A). Gnathopod 2 different from male gnathopod 2 in shape and size; gnathopod 2 slightly slender than gnathopod 1; basis, ischium and merus without comb-scales; carpus with pectinate lobe with comb-scales and two serrate setae on ventral face; propodus length about 1.5 times maximum width, four serrate setae on ventral (inner) face, anterodistal margin with comb-scales and two simple setae, disto-posterior margin without comb-scales and with cluster of simple setae, mid-posterior margin with one simple seta; dactylus claw-like with comb-scales and one plumose setae (Fig. 8B). Habitat. Freshwater, epigean. The Cachoeira Grande watershed, from the source to the outfall, is inserted in the Monumento Natural Municipal da Lagoa do Peri. The Cachoeira Grande watershed is composed of first, second, and third-order streams that trains an area of 1.66 km 2. In this portion, the Atlantic Rainforest is at an advanced stage of regeneration (Caruso 1983), with a thick canopy cover of 73–88%. The stretch of the stream where the H. insulae n. sp. was found is characterized as a second order stream located in the Cachoeira Grande watershed (48°32’22”W – 27°43’55.00”S). In this stretch, there is primary riparian vegetation with about 90% of vegetation cover, abundant diversity of habitats with stony substrate, and accumulation of allochthonous organic matter in stretches of rapids and backwaters. The stretch has an average width of 2.95 m and 0.22 m deep, with good oxygenation (8.62 mg /l), low electrical conductivity (60.26 μS/cm) and hydrogen potential close to neutrality (7.45). The holotype was collected in organic material deposited in backwater. The Ribeirão Grande watershed is composed of first, second, and third-order streams. The vegetation is in an intermediate stage of conservation because of anthropogenic impact, e.g., deforestation watershed. The streams have riparian vegetation composed of secondary forest and introduced species; thus, the tree cover shows a sparse canopy, and the streams receive greater solar insolation. The surrounding area is characterized by traditional families who explore the preserved area by developing subsistence agriculture (Schmitt et al. 2019). Some individuals of H. insulae n. sp. were sampled in a stretch of a third-order stream (48º32’03’W–27º44’08’S) located in the Ribeirão Grande watershed. This stretch of the stream presents at least 30 m of riparian vegetation width along the sampled section. This stream is characterized by pools and riffles stretches with the benthic substrate composed mainly of sand and coarse organic matter. The stretch presents average values of 2.61 in width and 0.24 m in depth with running water (0,16 m/s), good oxygenation (8.41 mg /l), low electrical conductivity (53.8 μS/cm) and hydrogen potential close to neutrality (7.21). The main environmental impacts that can interfere with the local biodiversity of the Cachoeira Grande watershed are related to the urban occupation around the MNLP. On the other hand, around the main rivers and streams of the Ribeirão Grande watershed, there is a development of subsistence agriculture by traditional families (that already occupied the area before the implementation of the UC) with small plantations of banana, beans, cassava, corn, and others, plus small livestock (Schmitt et al. 2019). However, it is noteworthy that the streams sampled have riparian vegetation along its entire extension. Etymology. The species epithet “ insulae ” is in reference of the first species of the genus in a Brazil island. Remarks. In general, H. insulae n. sp. has similarities with most species from state of Santa Catarina, and the neighboring states, Parana and Rio Grande do Sul, in some features of taxonomic importance, such as the presence of a curved seta on the inner ramus of uropod 1 (absent only in H. pseudoazteca González & Watling, 2003, and H. longipropodus Limberger, Graichen & Castiglioni, 2021). The new species differs in relation to the body surface smooth only from H. kaingang Araujo & Cardoso, 2013 (flanges on pleonites 1 and 2), H. pleoacuta González, Bond-Buckup & Araujo, 2006 (flanges on pereonite 7 and pleonites 1, 2 and 3) and H. pseudoazteca (flanges on pereonite 7 and pleonites 1 and 2) (Table 1). Other similarity is the location of the sternal gills from the 2nd to the 7th thoracic segment (except H. curvispina Shoemaker, 1942, H. imbya Rodrigues & Bueno, 2012, H. montenegrinae Bond-Buckup & Araujo, 1998, H. palmeirensis Streck-Marx & Castiglioni, 2020, and H. pseudoazteca, which present from the 3rd to the 7th). However, it is noticed that H. insulae n. sp. differs from the other species from state of Santa Catarina in some remarkable features. The species H. insulae n. sp. has morphological differences in the maxilla 2 (two papposerrate setae, one smaller) when comparing with H. catarinensis (only one papposerrate setae) and H. rioantensis (several papposerrate setae), but shares similarity with H. sambaqui and H. lagoana, which also present two papposerrate setae, one smaller than the other (Table 1). The four species with occurrence in the state of Santa Catarina, differ from H. insulae n. sp. in the number of serrate setae in the inner face of male gnathopod 1, number of setae of uropods 1, 2 and 3, and number and shape of setae on telson (Table 1). The species H. insulae n. sp. has a greater number of setae in the peduncle of uropod 3 (9–10 cuspidate setae), when comparing to H. catarinensis, H. rioantensis (both with six cuspidate setae), H. sambaqui (three cuspidate setae) and H. lagoana (five cuspidate setae) (Table 1). It was observed that only H. lagoana share similarity with H. insulae n. sp. in the number of setae on telson, which also present six cuspidate setae, but the new species present telson wider than long and H. lagoana, just like the other species from state of Santa Catarina, present telson longer than wide. When comparing with the species of the neighboring states, Rio Grande do Sul and Paraná, H. insulae n. sp. also differ in relation to the number and shape of setae of the gnathopods, uropods and telson (Table 1). Hyalella gauchensis Streck & Castiglioni, 2017, H. kaigang, H. longipropodus and H. minuana Talhaferro & Bueno, 2021 are similar to H. insulae n. sp. in relation to the presence of two papposerrate setae (one longer than the other) on the inner margin of maxilla 2. When comparing the number of serrate setae in the inner face of propodus of gnathopod 1, it was noticed that only H. imbya and H. longipropodus resembles H. insulae n. sp. (with seven serrate setae) (Table 1). The only species that resembles Hyalella n. sp. when comparing the type and number of setae of telson is H. gauchensis Streck & Castiglioni, 2017 (with six cuspidate setae) (Table 1).

Hyalella fatimae n. sp. (Figs. 1–7) Type locality. Argentina, Salta Province, Los Andes Department: 24°13’6.41’’S 66°28’24.09’’W (Fig. 1), 4458 m a.s.l., peatbog near to Chorrillos. Type specimens: Holotype male, body length 8.10 mm (FML-CRUST 01273). Paratypes: one female (ovigerous), body length 6.92 mm (FML-CRUST 01274); two males, body length 5.8 and 7.57 mm (FML-CRUST 01275). All collected at type locality (Fig. 1), 18-XII-2013; Col. J. Rodríguez. Additional material: Argentina; 3 males, 7 females Argentina; Salta Province, peatbogs vega Abra de Chorrillos, left branch (VC1C); 24°11’38’’S 66°32’15’’W (Fig. 1). 4358 m a.s.l., 17-XII-2013; Col. J. Rodríguez (FML- CRUST 01277). One female, Argentina, Salta Province, Los Andes Department: 24°13’6.41’’S 66°28’24.09’’W, 4458 m a.s.l., peatbog near to Chorrillos, 18-XII-2013; Col. J. Rodríguez (FML-CRUST 01276, SEM preparations). Diagnosis. Antenna 1 shorter, barely longer than head. Inner plate of maxilla 1 reaching base of palp, with two short and robust pappose setae. Inner plate of maxilla 2 with one robust papposerrate seta. Propodus of male gnathopod 1 hatchet-shaped, with nine serrate setae on inner face, palm angle with three cuspidate setae with accessory seta (one longer external, two shorter, internal). Epimeral plate I rounded, II and III posterodistally slightly acuminate. Etymology. The species epithet “ fatimae “ honors the limnologist Fátima Romero (Fundación Miguel Lillo- Tucumán, Argentina) for her contributions to the study of freshwater macroinvertebrates in Argentina. Habitat. Freshwater, epigean. Description of Holotype male. Size, 8.10 mm. Head smaller than first two thoracic segments combined. Eyes pigmented, large, subrounded. Body surface smooth. Epimeral plate I rounded, different from plates II and III, which are posterodistally slightly acuminate (Fig. 4A). Pereiopodal coxae I to III subequal in shape, slightly overlapping. Acumination in coxae absent. Coxa III narrower than IV. Coxa IV deeper than wide, excavated posteriorly. Posterior lobe of coxa V deeper than anterior lobe. Anterior lobe of coxa VI small (Figs 7A–D). Antenna 1 (Fig. 4B) much shorter than antenna 2 but longer than peduncle of latter; peduncle shorter than head, first segment &frac13; longer than second one, third segment slightly shorter than second; all segments of peduncle with group of simple setae; in addition, second segment with medial plumose seta. Flagellum of eight articles, all with groups of simple setae, additionally 1–2 aesthetascs per article arranged distally between articles 5–7, distal article with group of four long setae and one small simple seta. Antenna 2 (Fig. 4C) less than half of body length, with peduncle slightly longer than head, article 4 shorter than article 5; articles 3–5 with groups of simple setae, and 1–2 plumose setae, article 5 with other simple medial setae. Flagellum with 10 articles, distally with group of simple setae, and some articles with plumose setae. Labrum (Fig. 4D) ventral margin truncate, covered by short distal setules. Mandibles basic amphipodan type (sensu Watling 1993); each with well-developed large, cylindrical, triturative molar. Left mandible (Fig. 4F) incisor 6-denticulate (three short, three long); lacinia 3-denticulate; setal row with five pappose setae. Right mandible (Fig. 4E) incisor 6-denticulate (three very short, three long); lacinia complex, setal row with two pappose setae. Lower lip (Fig. 5A) outer lobes rounded with distal and internal setules, mandibular projection of outer lobes round. Inner lobes wanting Maxilla 1 (Fig. 5B) palp unsegmented, longer than wide, reaching more than half the distance between base of palp and base of setae on outer plate, setulose and with strong papposerrate seta distally; nine serrate long distal setae on outer plate; inner plate slender, shorter than outer one, bearing two apical papposerrate setae; both plates with setules and denticles on outer face. Maxilla 2 (Fig. 5C) plates subequal in length. Inner plate with one strong, long papposerrate seta proximally on inner margin. Both plates sparsely setulose, with apex wearing serrulate, simple, pappose and serrate setae as figured. Maxilliped (Fig. 5D) inner plate apically rounded, longer than wide, with three strong cuspidate setae, apex and margins with setules, pappose and simple setae; outer plate with apical pappose setae continuous with a row of simple setae that cover most of medial margin; outer distal face of both plates with 1–2 short setae; palp longer than outer plate, 4-segmented, second segment longer than wide; inner margins of segments 2 and 3 with several long simple setae; outer distal face of segments 1 and 2 with 1–3 setae; inner distal margin of segment 3 with seven serrate setae; segment 4 unguiform, shorter than segment 3, with thin apical seta shorter than distal nail. Coxal gills on gnathopod 2 (Fig. 6B) to pereiopod 6 (Figs. 7A–C), sac-like. Sternal gills tubular on pereionites II–VII. Gnathopod 1 (Fig. 6A) subchelate. Coxal plate margin with small simple setae. Basis, ischium and merus with serrate setae on posterior margin. Carpus longer than wide, with strong, wide concave posterior lobe, border pectinate and with several serrate setae. Propodus length less than two times maximum width, hatchet-shaped, anterodistal border with group of thin simple setae, inner face with nine serrate setae; denticles of type T1 on postero-distal border; palm slope slightly transverse, margin slightly convex covered with simple setae; palm angle with three cuspidate setae with accessory seta (one longer, external). Dactylus claw-like, inner margin with denticles and three endal setae, outer margin with one thin plumose seta dorsally. Palmar Index (sensu Ruffo 1973) = 0.44. Gnathopod 2 (Fig. 6B) subchelate. Basis approximately 2x longer than wide; posterior margin with five long serrate setae. Basis, ischium and merus each with group of setae on postero-distal border. Posterior lobe of carpus elongated, border pectinate with some serrate setae. Propodus ovate, with scales on postero-distal margin; palm margin slightly longer than posterior margin, with slope slightly oblique, straight and regular with several strong short and medium-length setae; antero-distal border with cluster of thin simple setae; palm angle with two cuspidate setae with an accessory seta. Dactylus claw-like with several endal setae and comb-scales, congruent with palm, with one thin plumose seta dorsally. Palmar Index (sensu Ruffo 1973) = 0.47. Pereiopods 3–4 (Figs. 7A, B) similar in size and shape. Coxal plate of pereiopod 3 longer than wide; coxa of pereiopod 4 excavated posteriorly, deeper than wide; both coxal plates with margins bordered with thin simple setae; posterior margin of basis, ischium, merus, carpus and propodus with simple or cuspidate setae; anterior margin of merus, carpus and propodus with cluster of distal setae; dactylus less than half length of propodus, with one plumose seta. Pereiopods 5–7 (Figs. 7C–E) pereiopod 5 distinctly shorter than 6 and 7, which are subequal in length. Coxal plate of pereiopod 5: wider than long, posterior lobe deeper than anterior; coxa of pereiopod 6: as long as wide, anterior lobe much reduced; coxa of pereiopod 7: wider than long; all coxal plates with thin simple setae on margin. Posterior margin of basis of pereiopods 5–7 expanded (more so in 5 and 7 than in 6) and finely serrate. Anterior margins of basis, merus, carpus and propodus with marginal clusters of 2–6 cuspidate setae; dactylus 5 less than half length of propodus, dactylus 6–7 not reaching half length of propodus, all with a plumose seta. Pleopods (Fig. 8A) all similar, peduncle shorter than rami, biramous; rami multi-annulated and bearing long plumose setae. Uropod 1 (Fig. 8B) peduncle 1.4 times longer than rami, with three proximal cuspidate setae aligned in a longitudinal row and two other distal cuspidate setae; rami subequal in length; outer ramus with two dorsal and four distal cuspidate setae; inner ramus with two dorsal and five distal cuspidate setae (one of them slender); modified curved seta on inner side of inner ramus wanting. Uropod 2 (Fig. 8C) shorter than uropod 1; peduncle subequal to rami, with four cuspidate setae; rami subequal with two proximo-dorsal cuspidate setae; inner ramus of left uropod 2 with four cuspidate setae at the distal end, one of them longer than rest; apex of inner ramus of right uropod 2 with five cuspidate setae; apex of outer ramus with four cuspidate setae (one of them shorter than rest). Uropod 3 (Fig. 8D) much shorter than peduncle of uropod 2; peduncle slightly longer than wide, wider than ramus, with two strong cuspidate distal setae and two other thin simple marginal setae; outer ramus unsegmented, shorter than peduncle, basal width near 1.6 times tip of ramus, apex with three simple setae, and one cuspidate shorter seta. Telson (Figs. 8E, F) wider than long, entire, bearing two widely apart simple setae, symmetrically distributed on distal margin, and with two or three short plumose setae at each side laterally to the simple ones. Females. Measurements: Body length ranging from 3.28 to 7.5 mm; mean body size: 4.59 mm (8 individuals). Habitus similar to male except for the following characters: Antenna 1 flagellum with 5–7 articles. Antenna 2 flagellum with 6–10 articles. Gnathopods 1 and 2 similar to each other in size and shape. Gnathopod 1, inner face of propodus with eight serrate setae (Fig. 6C). Gnathopod 2, inner face of propodus with five serrate setae (Fig. 6D); gnathopod 2 differs from that of the male in shape and smaller propodus. Oostegites subtriangular, with curled setae on the margins (Fig. 6D). Variability in males: Measurements: body length ranging from 5.8 to 9.5 mm; mean body size: 7.8 mm (6 individuals). Some variations were observed in the setae of gnathopod 1 propodus, setae of uropods 2–3, and number of flagellum articles of antennae. Gnathopod 1: some males with seven serrate setae on inner face of propodus (instead of nine). Uropods: in one adult male, peduncle of right uropod 3 with four connate setae (left peduncle with three); another adult male, uropod 3 peduncle with three connate setae, two long and one short, ramus with one simple seta (instead of three). In one adult male, uropod 2 peduncle with four marginal cuspidate setae (two in holotype). Number of articles in antennal flagellum increases with size of the individual, in largest male (9.5 mm) A1 with 10–11 articles, A2 with 13–14 articles; in smallest male (5.8 mm) A1 had only 8 articles and A2 only 10 articles.

Hyalella fatimae n. sp. (Figs. 1���7) Type locality. Argentina, Salta Province, Los Andes Department: 24��13���6.41������S 66��28���24.09������W (Fig. 1), 4458 m a.s.l., peatbog near to Chorrillos. Type specimens: Holotype male, body length 8.10 mm (FML-CRUST 01273). Paratypes: one female (ovigerous), body length 6.92 mm (FML-CRUST 01274); two males, body length 5.8 and 7.57 mm (FML-CRUST 01275). All collected at type locality (Fig. 1), 18-XII-2013; Col. J. Rodr��guez. Additional material: Argentina; 3 males, 7 females Argentina; Salta Province, peatbogs vega Abra de Chorrillos, left branch (VC1C); 24��11���38������S 66��32���15������W (Fig. 1). 4358 m a.s.l., 17-XII-2013; Col. J. Rodr��guez (FML- CRUST 01277). One female, Argentina, Salta Province, Los Andes Department: 24��13���6.41������S 66��28���24.09������W, 4458 m a.s.l., peatbog near to Chorrillos, 18-XII-2013; Col. J. Rodr��guez (FML-CRUST 01276, SEM preparations). Diagnosis. Antenna 1 shorter, barely longer than head. Inner plate of maxilla 1 reaching base of palp, with two short and robust pappose setae. Inner plate of maxilla 2 with one robust papposerrate seta. Propodus of male gnathopod 1 hatchet-shaped, with nine serrate setae on inner face, palm angle with three cuspidate setae with accessory seta (one longer external, two shorter, internal). Epimeral plate I rounded, II and III posterodistally slightly acuminate. Etymology. The species epithet ��� fatimae ��� honors the limnologist F��tima Romero (Fundaci��n Miguel Lillo- Tucum��n, Argentina) for her contributions to the study of freshwater macroinvertebrates in Argentina. Habitat. Freshwater, epigean. Description of Holotype male. Size, 8.10 mm. Head smaller than first two thoracic segments combined. Eyes pigmented, large, subrounded. Body surface smooth. Epimeral plate I rounded, different from plates II and III, which are posterodistally slightly acuminate (Fig. 4A). Pereiopodal coxae I to III subequal in shape, slightly overlapping. Acumination in coxae absent. Coxa III narrower than IV. Coxa IV deeper than wide, excavated posteriorly. Posterior lobe of coxa V deeper than anterior lobe. Anterior lobe of coxa VI small (Figs 7A���D). Antenna 1 (Fig. 4B) much shorter than antenna 2 but longer than peduncle of latter; peduncle shorter than head, first segment &frac13; longer than second one, third segment slightly shorter than second; all segments of peduncle with group of simple setae; in addition, second segment with medial plumose seta. Flagellum of eight articles, all with groups of simple setae, additionally 1���2 aesthetascs per article arranged distally between articles 5���7, distal article with group of four long setae and one small simple seta. Antenna 2 (Fig. 4C) less than half of body length, with peduncle slightly longer than head, article 4 shorter than article 5; articles 3���5 with groups of simple setae, and 1���2 plumose setae, article 5 with other simple medial setae. Flagellum with 10 articles, distally with group of simple setae, and some articles with plumose setae. Labrum (Fig. 4D) ventral margin truncate, covered by short distal setules. Mandibles basic amphipodan type (sensu Watling 1993); each with well-developed large, cylindrical, triturative molar. Left mandible (Fig. 4F) incisor 6-denticulate (three short, three long); lacinia 3-denticulate; setal row with five pappose setae. Right mandible (Fig. 4E) incisor 6-denticulate (three very short, three long); lacinia complex, setal row with two pappose setae. Lower lip (Fig. 5A) outer lobes rounded with distal and internal setules, mandibular projection of outer lobes round. Inner lobes wanting Maxilla 1 (Fig. 5B) palp unsegmented, longer than wide, reaching more than half the distance between base of palp and base of setae on outer plate, setulose and with strong papposerrate seta distally; nine serrate long distal setae on outer plate; inner plate slender, shorter than outer one, bearing two apical papposerrate setae; both plates with setules and denticles on outer face. Maxilla 2 (Fig. 5C) plates subequal in length. Inner plate with one strong, long papposerrate seta proximally on inner margin. Both plates sparsely setulose, with apex wearing serrulate, simple, pappose and serrate setae as figured. Maxilliped (Fig. 5D) inner plate apically rounded, longer than wide, with three strong cuspidate setae, apex and margins with setules, pappose and simple setae; outer plate with apical pappose setae continuous with a row of simple setae that cover most of medial margin; outer distal face of both plates with 1���2 short setae; palp longer than outer plate, 4-segmented, second segment longer than wide; inner margins of segments 2 and 3 with several long simple setae; outer distal face of segments 1 and 2 with 1���3 setae; inner distal margin of segment 3 with seven serrate setae; segment 4 unguiform, shorter than segment 3, with thin apical seta shorter than distal nail. Coxal gills on gnathopod 2 (Fig. 6B) to pereiopod 6 (Figs. 7A���C), sac-like. Sternal gills tubular on pereionites II���VII. Gnathopod 1 (Fig. 6A) subchelate. Coxal plate margin with small simple setae. Basis, ischium and merus with serrate setae on posterior margin. Carpus longer than wide, with strong, wide concave posterior lobe, border pectinate and with several serrate setae. Propodus length less than two times maximum width, hatchet-shaped, anterodistal border with group of thin simple setae, inner face with nine serrate setae; denticles of type T1 on postero-distal border; palm slope slightly transverse, margin slightly convex covered with simple setae; palm angle with three cuspidate setae with accessory seta (one longer, external). Dactylus claw-like, inner margin with denticles and three endal setae, outer margin with one thin plumose seta dorsally. Palmar Index (sensu Ruffo 1973) = 0.44. Gnathopod 2 (Fig. 6B) subchelate. Basis approximately 2x longer than wide; posterior margin with five long serrate setae. Basis, ischium and merus each with group of setae on postero-distal border. Posterior lobe of carpus elongated, border pectinate with some serrate setae. Propodus ovate, with scales on postero-distal margin; palm margin slightly longer than posterior margin, with slope slightly oblique, straight and regular with several strong short and medium-length setae; antero-distal border with cluster of thin simple setae; palm angle with two cuspidate setae with an accessory seta. Dactylus claw-like with several endal setae and comb-scales, congruent with palm, with one thin plumose seta dorsally. Palmar Index (sensu Ruffo 1973) = 0.47. Pereiopods 3���4 (Figs. 7A, B) similar in size and shape. Coxal plate of pereiopod 3 longer than wide; coxa of pereiopod 4 excavated posteriorly, deeper than wide; both coxal plates with margins bordered with thin simple setae; posterior margin of basis, ischium, merus, carpus and propodus with simple or cuspidate setae; anterior margin of merus, carpus and propodus with cluster of distal setae; dactylus less than half length of propodus, with one plumose seta. Pereiopods 5���7 (Figs. 7C���E) pereiopod 5 distinctly shorter than 6 and 7, which are subequal in length. Coxal plate of pereiopod 5: wider than long, posterior lobe deeper than anterior; coxa of pereiopod 6: as long as wide, anterior lobe much reduced; coxa of pereiopod 7: wider than long; all coxal plates with thin simple setae on margin. Posterior margin of basis of pereiopods 5���7 expanded (more so in 5 and 7 than in 6) and finely serrate. Anterior margins of basis, merus, carpus and propodus with marginal clusters of 2���6 cuspidate setae; dactylus 5 less than half length of propodus, dactylus 6���7 not reaching half length of propodus, all with a plumose seta. Pleopods (Fig. 8A) all similar, peduncle shorter than rami, biramous; rami multi-annulated and bearing long plumose setae. Uropod 1 (Fig. 8B) peduncle 1.4 times longer than rami, with three proximal cuspidate setae aligned in a longitudinal row and two other distal cuspidate setae; rami subequal in length; outer ramus with two dorsal and four distal cuspidate setae; inner ramus with two dorsal and five distal cuspidate setae (one of them slender); modified curved seta on inner side of inner ramus wanting. Uropod 2 (Fig. 8C) shorter than uropod 1; peduncle subequal to rami, with four cuspidate setae; rami subequal with two proximo-dorsal cuspidate setae; inner ramus of left uropod 2 with four cuspidate setae at the distal end, one of them longer than rest; apex of inner ramus of right uropod 2 with five cuspidate setae; apex of outer ramus with four cuspidate setae (one of them shorter than rest). Uropod 3 (Fig. 8D) much shorter than peduncle of uropod 2; peduncle slightly longer than wide, wider than ramus, with two strong cuspidate distal setae and two other thin simple marginal setae; outer ramus unsegmented, shorter than peduncle, basal width near 1.6 times tip of ramus, apex with three simple setae, and one cuspidate shorter seta. Telson (Figs. 8E, F) wider than long, entire, bearing two widely apart simple setae, symmetrically distributed on distal margin, and with two or three short plumose setae at each side laterally to the simple ones. Females. Measurements: Body length ranging from 3.28 to 7.5 mm; mean body size: 4.59 mm (8 individuals). Habitus similar to male except for the following characters: Antenna 1 flagellum with 5���7 articles. Antenna 2 flagellum with 6���10 articles. Gnathopods 1 and 2 similar to each other in size and shape. Gnathopod 1, inner face of propodus with eight serrate setae (Fig. 6C). Gnathopod 2, inner face of propodus with five serrate setae (Fig. 6D); gnathopod 2 differs from that of the male in shape and smaller propodus. Oostegites subtriangular, with curled setae on the margins (Fig. 6D). Variability in males: Measurements: body length ranging from 5.8 to 9.5 mm; mean body size: 7.8 mm (6 individuals). Some variations were observed in the setae of gnathopod 1 propodus, setae of uropods 2���3, and number of flagellum articles of antennae. Gnathopod 1: some males with seven serrate setae on inner face of propodus (instead of nine). Uropods: in one adult male, peduncle of right uropod 3 with four connate setae (left peduncle with three); another adult male, uropod 3 peduncle with three connate setae, two long and one short, ramus with one simple seta (instead of three). In one adult male, uropod 2 peduncle with four marginal cuspidate setae (two in holotype). Number of articles in antennal flagellum increases with size of the individual, in largest male (9.5 mm) A1 with 10���11 articles, A2 with 13���14 articles; in smallest male (5.8 mm) A1 had only 8 articles and A2 only 10 articles., Published as part of Ver��nica, Isa Miranda ��gueda & Alejandra, Peralta Marcela, 2022, A new Hyalella species (Crustacea: Amphipoda: Hyalellidae) from South American Highlands (Argentina) with comments on its cuticular ultrastructure, pp. 202-218 in Zootaxa 5105 (2) on pages 203-208, DOI: 10.11646/zootaxa.5105.2.2, http://zenodo.org/record/6332543, {"references":["Watling, L. (1993) Functional morphology of the amphipod. Journal of Natural History, 27, 837 - 849.","Ruffo, S. (1973) Contributo alla revisione del genere Bogidiella Hertzog (Crustacea, Amphipoda, Gammaridae). Bolletino dell' Istituto di Entomologia della Universita degli Studi di Bologna, 31, 49 - 77."]}

Hyalella is a genus of epigean freshwater amphipods endemic to the Americas. The study of morphological characters alone has traditionally dominated the description of new species. Recently, molecular systematics tools have contributed to identifying many cryptic species and a high level of convergent evolution in species complexes from North America and the South American highlands. In this study, we evaluate for the first time the molecular diversity in Hyalella spp. in Uruguay, a country located in the humid pampa ecoregion, based on four molecular markers. Thus, we investigate the systematic position of H. curvispina in the context of the available phylogenetic hypothesis for the genus. Phylogenetic and morphological analyses confirm that there is a “curvispina complex”. This complex includes H. curvispina and several similar morphological forms but is paraphyletic in relation to some altiplano species. In addition, we found one provisional new species. The results obtained are contrasted with previous studies to help understand the mechanisms of genetic differentiation and speciation of the genus, which seems to have a strong tendency towards morphological convergence.