Hyalella mboitui, Mussini & Stepan & Vargas, 2024

Mussini, Giovanni, Stepan, Nicole D. & Vargas, Gersey, 2024, Two new species of Hyalella (Amphipoda, Dogielinotidae) from the Humid Chaco ecoregion of Paraguay, ZooKeys 1191, pp. 105-127 : 105

publication ID	https://dx.doi.org/10.3897/zookeys.1191.113840
publication LSID	lsid:zoobank.org:pub:389318B6-701B-43B0-9B24-08185E930018
persistent identifier	https://treatment.plazi.org/id/B7930020-036E-457F-AEDF-26DE31C2B599
taxon LSID	lsid:zoobank.org:act:B7930020-036E-457F-AEDF-26DE31C2B599
treatment provided by	ZooKeys by Pensoft
scientific name	Hyalella mboitui
status	sp. nov.

Treatment

Hyalella mboitui sp. nov.

Type material.

Holotype, male (Fig. 1A View Figure 1 ), total body length = 8.29 mm, head length = 0.89 mm (CIPLT-O-38); Allotype female (Fig. 2A View Figure 2 ), total body length = 7.10 mm, head length = 0.70 mm (CIPLT-O-38). Paraguay, Department of Ñeembucú, Pilar, Ring Road field locality (26°52'31"S, 58°14'59"W), September, 08, 2021. Paratypes. 43 males, 54 females, Ring Road (CIPLT-O-37; 26°52'31"S, 58°14'59"W) and San Lorenzo (CIPTL-O-39; 26°52'35"S, 58°18'40"W) field localities.

Type locality.

Paraguay, Department of Ñeembucú, Pilar, Ring Road field locality (26°52'31"S, 58°14'59"W).

Diagnosis.

Flagella of antennae 1 and 2 with 13-14 and 16-17 articles, respectively. Left mandible incisor toothed, 5-denticulate; left lacinia mobilis multi-denticulate, with median serrated surface and two prominent elongated denticles laterally. Gnathopod 1 propodus subtriangular, without triangular space between propodus and dactylus, with papposerrate setae on disto-anterior corner. Gnathopod 2 propodus with papposerrate setae on disto-posterior margin, with palm with pronounced cup for dactylus. Pereopod 5 shorter than other pereopods. Uropod 1 endopod with a curved seta. Uropod 3 ramus dorsal margin without setae. Uropod 3 peduncle with two cuspidate setae and four simple setae apically. Uropod 3 peduncle longer than wide (rectangular).

Description.

Male (Figs 1 View Figure 1 - 5 View Figure 5 ). Mean total body length: 7.98 mm; mean head length: 0.84 mm (N = 44). Body surface smooth. Epimeral plates not acuminate. Head smaller than first two thoracic segments, typically gammaridean, rostrum absent. Eyes pigmented, rounded, located between insertion of antennae 1 and 2 (Fig. 2A View Figure 2 ).

Antenna 1 about 2.2 × shorter than body length, 1.4 × shorter than antenna 2, 1.8 × longer than peduncle of antenna 2; peduncle 1.1 × longer than head length; flagellum with 13-14 articles, 1.5 × longer than peduncle; aesthetascs occurring distally after article 4 (Fig. 2B View Figure 2 ).

Antenna 2 about 1.5 × shorter than body length; peduncle 1.6 × longer than head length; articles 1 to 3 with several simple setae on distal margin; flagellum 1.7 × longer than peduncle, with 16-17 articles, with basal article elongated, with several simple setae on distal margins, and with four simple setae apically (Fig. 2C View Figure 2 ).

Basic amphipodan mandibles (sensu Watling 1993), without palp; left incisor toothed, 5-denticulate; left lacinia mobilis multi-denticulate, with medial surface with multiple small serrated denticles and two prominent elongated denticles laterally, setal row with five papposerrate setae, with setules, molar process large and cylindrical, triturative, with one accessory seta (Fig. 2E View Figure 2 ). Right mandible incisor 6-denticulate; lacinia 5-denticulate, setal row with six papposerrate setae, with setules.

Upper lip distal margin truncate; distal border covered by setules on ventral and dorsal faces (Fig. 2D View Figure 2 ). Lower lip outer lobes rounded, not notched, with several setules on dorsal and ventral faces (Fig. 2G View Figure 2 ).

Maxilla 1 inner plate slender, 1.8 × shorter than outer plate, with two apical papposerrate setae and several setules laterally. Outer plate with nine serrate setae and several setules (Fig. 2H View Figure 2 ). Palp short, uniarticulate, 1.0 × longer than wide, with apical and lateral setules, reaching less than half distance between base of palp and base of setae on outer plate.

Maxilla 2 inner and outer plates subequal in length and width. Inner plate with one papposerrate seta and several simple and serrate setae apically, and several setules on inner face; outer plate with several simple setae on apex and margin, longest apically (Fig. 2I View Figure 2 ).

Maxilliped inner plate 2.0 × longer than wide, apically truncated, with two cuspidate setae, several simple setae apically, and several setules on inner margin, comb-scales absent; outer plate approximately 1.3 × longer than inner plate, apically rounded, with several apical and lateral simple setae, comb-scales absent; palp approximately 2.1 × longer than inner plate, with four articles; article 1 1.1 × longer than wide, inner margin with few simple setae; article 2 1.5 × longer than wide, inner margin with several simple setae, outer margin with few simple setae; article 3 1.8 × longer than wide, inner and outer margins with several long simple setae; article 4 unguiform, 3.0 × shorter than third article, 1.6 × longer than wide, inner margin with several long simple setae, with distal simple seta, with distal nail and comb-scales absent (Fig. 2J View Figure 2 ).

Gnathopod 1 subchelate; coxal plate 2.1 × wider than long, with several simple setae on anterior and posterior margins; basis with one simple seta on anterior margin and one on disto-posterior corner; ischium with few simple setae on disto-posterior corner; merus with few simple setae on posterior margin; carpus 1.3 × longer than wide, 1.1 × longer and wider than propodus, posterior lobe produced and forming scoop-like structure, pectinate margin with several serrate setae, comb-scales and polygonal pattern; propodus 1.3 × longer than wide, hammer-shaped, with several simple setae on anterior margin, with several papposerrate setae on disto-anterior corner; palm slope oblique, with several simple setae, margin convex, disto-posterior corner with long simple setae, and with a pronounced cup for dactylus; dactylus claw-like, congruent with palm, without comb-scales (Fig. 3A View Figure 3 ).

Gnathopod 2 subchelate; coxal plate 1.6 × wider than long; basis with few simple setae on posterior margin and one serrate seta on disto-anterior margin; ischium and merus with few simple setae on posterior margin; carpus 1.8 × wider than long, posterior lobe slim, produced between merus and propodus, margin pectinate with several serrate setae; propodus ovate, 1.4 × longer than wide, comb-scales absent; palm subequal to posterior margin of propodus, slope oblique, margin convex, slightly irregular, with several simple setae and cuspidate setae with accessory seta; disto-posterior corner with two small cuspidate setae and several papposerrate setae, and with a pronounced cup for dactylus; dactylus claw-like, congruent with palm, without comb-scales (Fig. 3B View Figure 3 ).

Pereopods 3 to 7 simple. Pereopod 4 (Fig. 4B View Figure 4 ) with several simple setae on basis posterior margin; pereopods 3 (Fig. 4A View Figure 4 ) and 4 with several simple setae on merus and carpus posterior margins, with several simple and cuspidate setae on propodus posterior margins; dactylus approximately 3.5 × shorter than propodus, in both. Pereopods 5, 6 and 7 (Fig. 4C-E View Figure 4 ) with merus, carpus and propodus posterior margins with several cuspidate and simple, dactylus 1.8 ×, 2.1 × and 2.2 × shorter than propodus, respectively, unguiform, with plumose seta dorsally on pereopods 6 and 7. Pereopod 3 and 4 of similar sizes; pereopod 5 smaller than others; pereopod 6 slightly shorter than pereopod 7.

Pleopods not modified, biramous, elongated; peduncle 4.0 × longer than wide, 1.7 × mean size of rami, with coupling spines distally; both rami multi-annulated, longer than peduncle, with articles decreasing in size distally, with several plumose setae (Fig. 5A View Figure 5 ).

Uropod 1 1.5 × longer than uropod 2; peduncle 1.1 × longer than longest ramus, with four cuspidate setae; inner ramus 1.4 × longer than outer ramus, 4.9 × longer than wide, with three dorsal cuspidate setae, with one long curved seta and four cuspidate setae apically; outer ramus with three dorsal cuspidate setae and four cuspidate setae apically (Fig. 5B View Figure 5 ).

Uropod 2 1.5 × shorter than uropod 1; peduncle rectangular, subequal in length to outer ramus and 1.2 × shorter than inner ramus, 2.0 × wider than outer ramus and 1.5 × than inner ramus, with two cuspidate setae; inner ramus slightly longer than outer ramus, with four cuspidate setae dorsally and three cuspidate setae apically; outer ramus with three cuspidate setae dorsally and four cuspidate setae apically (Fig. 5C View Figure 5 ).

Uropod 3 (Fig. 5D View Figure 5 ) 2.2 × shorter than peduncle of uropod 1 and 1.1 × than peduncle of uropod 2; peduncle 1.5 × longer than wide, 3.7 × wider than ramus, with six apical long cuspidate setae; inner ramus absent; outer ramus uniarticulate, 1.2 × longer than peduncle, with two cuspidate and four simple setae apically.

Telson entire, 1.1 × longer than wide, apically rounded, without setae laterally, with five apical cuspidate setae (Fig. 5E View Figure 5 ).

Coxal gills sac-like present on pereonites 3 to 6; sternal gills tubular and present on pereonites 3 to 7.

Female (Figs 1B View Figure 1 , 5E View Figure 5 , 6 View Figure 6 ). Mean total body length: 6.23 mm; mean head length: 0.62 mm (N = 55).

Antennae similar in shape to male. Antenna 1 flagellum with 10-11 articles. Antenna 2 flagellum with 16-17 articles.

Gnathopod 1 (Fig. 6A View Figure 6 ) similar to male gnathopod 1 in size but different in shape; basis with few simple setae on disto-anterior and disto-posterior margins; ischium with few simple setae on disto-posterior margin; merus with several simple setae and comb-scales on posterior margin; carpus 1.7 × longer than wide, 1.3 × longer and 1.2 × wider than propodus, with several simple setae on disto-anterior corner, posterior lobe produced and forming scoop-like structure, with pectinate margin, with comb-scales, with several serrate setae and polygonal pattern, and with three serrate setae on inner margin; propodus 1.6 × longer than wide, hammer-shaped, inner margin with six simple setae with accessory setae, dorsal margin with two simple setae, disto-anterior corner with several simple setae; palm 1.4 × shorter than posterior margin of propodus, slope transverse, margin slightly irregular, with several simple setae, with few simple setae and two cuspidate setae on disto-posterior corner; dactylus claw-like, with one plumose seta dorsally.

Gnathopod 2 (Fig. 6B View Figure 6 ) similar in size and shape to gnathopod 1; basis with one simple seta on posterior margin, with few simple setae on disto-anterior corner, and two pappose setae on disto-posterior corner; ischium with several simple setae on disto-posterior corner; merus with several simple setae on posterior margin; carpus 1.5 × longer than wide, 1.0 × longer and 1.3 × wider than propodus, with several simple setae on disto-anterior corner, posterior lobe produced and forming scoop-like structure with pectinate margin, with comb-scales, with several serrate setae and polygonal pattern, inner margin with few simple setae; propodus longer than wide, hammer-shaped, with comb-scales and several simple setae on disto-posterior margin, and several simple setae on disto-anterior corner; inner face with several simple setae; palm 1.9 × shorter than posterior margin of propodus, slope oblique, margin slightly concave, with several simple setae, disto-posterior corner with two cuspidate setae; dactylus claw-like, with one plumose seta dorsally.

Telson approximately as long as wide, with more convex lateral margins than in male, and with five cuspidate setae apically (Fig. 5F View Figure 5 ).

Uropod 1 similar in size and shape to male uropod 1, except for absence of curved seta.

Habitat.

Freshwater, epigean.

Distribution.

Paraguay, Department of Ñeembucú, Pilar. Field localities of Ring Road (26°52'31"S, 58°14'59"W) and San Lorenzo (26°52'35"S, 58°18'40"W).

Etymology.

In reference to Mbói Tu’i, one of the seven legendary monsters of Guaraní mythology and protector of wetlands and aquatic life. The species is named in Guaraní in honour of it being an endemic Paraguayan species.