Hyalella temimina, Bichuette, 2025

Hyalella temimina View in CoL sp. nov.

Penoni, Deotti and Bueno

( Fig. 9–15 View Figure 9 View Figure 10 View Figure 11 View Figure 12 View Figure 13 View Figure 14 View Figure 15 )

Zoobank: urn:lsid:zoobank.org:act:

Type material. Holotype: adult male ( Fig. 9A View Figure 9 ) (L 10.62 mm, HL 1.01 mm), MZUSP 45193 View Materials , Brazil, state of São Paulo, municipality of Apiaí, Parque Estadual Turístico do Alto Ribeira , Temimina II cave ( 24°22’36.8”S 48°33’56.2”W), November 2017, M.E. Bichuette, T. L.C. Scatolini, A. Pereira, D. Monteiro-Neto colls GoogleMaps . — Paratypes: 1 adult female ( Fig. 9B View Figure 9 ) (L 6.44 mm; HL 0.49 mm), MZUSP 45190 View Materials , same locality as the holotype, April 2018, M.E. Bichuette, T. L.C. Scatolini, A. Pereira, D. Monteiro-Neto colls GoogleMaps .; 1 male on slide CCUFLA 451, and 1 female on slide CCUFLA 452, same locality as the holotype, March 2009, M.E. Bichuette, T. L.C. Scatolini, A. Pereira, D. Monteiro-Neto colls GoogleMaps .

Diagnosis. Body surface smooth. Eyes round, pigmented. Epimeron 1 and 3 postero-distal margin subacute (angular and slightly rounded), epimeron 2 postero-distal margin acute (acute angle). Antenna 2 smaller than body length. Maxilla 1 palp longer than wide, longer than half distance between base of palp and base of seta on outer plate. Gnathopod 1 propodus posterior margins without comb-scales. Uropod 3 ramus longer than peduncle, with excavation close to apex, bearing cuspidate seta with accessory seta, simple seta, and short triangular cuspidate seta apically. Telson with 8 apical cuspidate setae with accessory seta and 3 small plumose setae on each side,

Deotti et al. Deotti et al.: New Hyalella

Nauplius, 33: e20250478

Deotti et al. Deotti et al.: New Hyalella

Nauplius, 33: e20250478

Deotti et al. Deotti et al.: New Hyalella

Nauplius, 33: e20250478

Nauplius, 33: e20250478

laterally. Coxal gills sac-like and present on segments 2 to 6. Sternal gills present on segments 3 to 7.

Description of male ( Fig. 9A View Figure 9 ). Mean body length: 10.77 mm ( N = 2); mean head length: 0.96 mm ( N =2). There were smaller animals observed at the collection site. Body surface smooth. Epimeral plates 2 acute and 1 and 3 subacute ( Fig. 7J View Figure 7 ). Coxae 1–4 subequal in size and shape, slightly overlapping.Coxa 1 similar to 2 and 3. Coxa 3 wider than 4. Coxa 4 longer than wide, excavated posteriorly. Coxa 5 posterior lobe narrower than anterior lobe. Coxa 6 as long as wide. Coxa 7 reduced. Eyes round and pigmented.

Antenna 1 ( Fig. 10A View Figure 10 ) about 3.2 × smaller than body length, 1.5 × smaller than antenna 2, 1.7 × longer than peduncle of antenna 2; peduncle 1.2 × longer than head; article 1 1.3 × longer than 2, article 3 1.3 × shorter than 1 and 1x shorter than article 2; flagellum with 20 articles, 2.5 ×longer than peduncle; aesthetascs occurring on flagellum from article 7 to 19 distally.

Antenna 2 ( Fig. 10B View Figure 10 ) 2.2 × smaller than body length; peduncle slender, 2.1 × longer than head; article 4 1.2 × shorter than article 5; flagellum with 23 articles, 1.5 × longer than peduncle.

Mandible without palp; incisor toothed; left ( Fig. 10C View Figure 10 ) lacinia mobilis with 5 teeth and setal row with 3 long and strong pappose setae and 1 shorter pappose seta, molar process without accessory seta; right mandible ( Figure 10D View Figure 10 ) with 2 longer central and 2 shorter pappose setae; molar process broad and cylindrical without accessory seta.

Upper lip( Fig. 10E View Figure 10 ) margin rounded; distal border covered by setules. Lower lip ( Figure 4F View Figure 4 ) outer lobes rounded and distally notched, with setules on dorsal and ventral faces.

Maxilla 1 ( Fig. 10G View Figure 10 ) inner plate slender, shorter than outer plate, with 2 apical papposerrate setae and setules distally. Outer plate with 9 serrate setae, increasing in size from inner to outer margin. Palp relatively long, uniarticulate, longer than wide, reaching more than half of distance between base of palp and base of seta on outer plate, with distal long seta.

Maxilla 2 ( Fig. 10H View Figure 10 ) inner plate subequal to outer plate, inner plate with 1 proximal and 1 distal strong papposerrate seta; inner and outer plates with several serrulate and simple setae, and setules distally.

Maxilliped ( Fig. 11A View Figure 11 ) inner plate longer than wide, with 3 cuspidate distal setae and up to 8 small pappose setae apically, without comb-scales; outer plate smaller than inner plate, with several long simple setae, without comb-scales; palp longer than inner, longer than outer plate, with 4 articles; article 1 triangular, outer margin with up to 3 long simple setae; article 2 longer than wide, inner margin with several long simple setae, outer margin with up to 6 long simple setae and 1 long and strong pappose seta; article 3 longer than wide, inner margin with several long simple setae, outer margin with pappose and long simple setae, without comb-scales; dactylus unguiform, relatively small, longer than wide, with distal setae simple and shorter than nail, without comb-scales, and distal nail present.

Gnathopod 1 ( Fig. 12A View Figure 12 ) subchelate; coxal plate 1.6× wider than longer, with simple setae on margin; basis and ischium with dorsal and apical serrate setae, without comb-scales; merus with pappose setae on distal margin, without comb-scales; carpus 2.6 × longer than wide, 1.1 × longer than propodus, with lateral distal lobe produced, with 8 serrate seta on disto-anterior margin, without comb-scales; posterior lobe without pectinate border or polygonal pattern, several pappose setae on margin and in inner face; propodus 1.4 × longer than wide, hammer-shaped, with several simple long setae on disto-anterior margin, comb-scales absent, inner face with many pappose setae, disto-posterior margin with simple setae and polygonal pattern; palm slope transverse, with many pappose setae with accessory seta, posterior distal corner with 2 long and strong cuspidate setae with accessory seta and polygonal pattern; dactylus claw-like, polygonal pattern present on disto-anterior margin, with 1 plumose seta dorsally and terminal simple setae on proximal margin.

Gnathopod 2 ( Fig. 12B View Figure 12 ) subchelate; coxal plate 1.7 × wider than long, with simple setae on margin; basis and ischium with several distal and apical serrate setae, without comb-scales; merus with up to 12 papposerrate setae on posterior margin,without comb-scales; carpus 2.6 × wider than long, posterior lobe slim produced between merus and propodus, forming scoop-like structure,margin with many papposerrate setae, polygonal pattern forming pectinate border; propodus ovate, 1.2 × longer than wide, polygonal pattern present and few small pappose setae on inner face; palm subequal to posterior margin of propodus, slope oblique, margin with row of several cuspidate setae with accessory seta and few simple and pappose setae, posterior distal corner with 2 short cuspidate setae and with cup for dactylus; dactylus claw-like, congruent with palm, plumose seta dorsally, terminal simple setae on proximal margin and comb-scales absent.

Pereopods 3 to 7 ( Fig.13A–E View Figure 13 ) simple. Pereopods 3 and 4 merus and carpus posterior margin with several simple setae, some cuspidate with accessory seta and some serrate setae; propodus posterior margin of pereopod 3 and 4 with several cuspidate setae with accessory seta, some simple setae and few serrate setae; dactylus 2.7 × and 2.8 × shorter than propodus, respectively, with plumose seta dorsally.Pereopods 5 to 7 merus, carpus and propodus posterior margin with several cuspidate setae most of them with accessory seta and some simple setae, dactylus 2.5 ×, 3.1 ×, and 2.8 × shorter than propodus, respectively, with plumose seta dorsally. Pereopod 3 and pereopod 4 similar sizes; pereopod 5 smaller than others; pereopod 6 longer than pereopod 7.

Pleopods ( Fig. 14A View Figure 14 ) peduncle longer than wide, shorter than both rami, with 2 coupling spines; both rami with several plumose setae.

Uropod 1 ( Fig. 14B View Figure 14 ) 1.4 × longer than uropod 2; peduncle 1.1 ×longer than outer ramus and subequal to inner ramus, with 5 cuspidate setae with accessory seta; inner ramus 1.2 × longer than outer ramus, with 3 dorsal cuspidate setae with accessory seta on margin and 3 small cuspidate setae with accessory seta, 2 longer cuspidate and 1 short triangular cuspidate seta apically, without curved seta; outer ramus with 3 dorsal cuspidate setae with accessory seta on margin and 2 longer, 1 shorter and 1 triangular cuspidate setae apically.

Uropod 2 ( Fig. 14C View Figure 14 ) peduncle subequal to outer ramus and 0.83 × size of inner ramus, with 4 cuspidate setae; inner ramus with 3 dorsal cuspidate setae with accessory seta and 5 cuspidate setae apically, only 1 with accessory seta; outer ramus with 4 dorsal cuspidate setae, sequentially increasing in size, and 2 short and 2 longer apical cuspidate setae.

Uropod 3 ( Fig. 14D View Figure 14 ) 0.8–0.9 × shorter than peduncle of uropod 2; peduncle longer than wide, with 4 cuspidate setae with accessory seta;inner ramus absent; outer ramus uniarticulate, 1.2 × longer than peduncle, with excavation close to apex, bearing 1 cuspidate seta with accessory seta and 1 simple seta, and 2 long, 2 short simple setae, 1 long cuspidate seta with accessory seta and 1 short triangular cuspidate seta apically.

Telson ( Fig. 14E View Figure 14 ) entire, 1.2 × longer than wide, apically rounded, with up to 8, almost symmetrical, small cuspidate setae with accessory seta apically, with 3 small plumose setae on each side, laterally.

Epimeron ( Fig. 11B View Figure 11 ) 1 and 3 subacute; epimeron 2 acute.

Coxal gills sac-like and present on pereonites 2 to 6. Sternal gills tubular, present on pereonites 3 to 7.

Description of female ( Fig. 9B View Figure 9 ). Mean body length: 10.24mm ( N = 3); mean head length: 0.73mm ( N =3).

Gnathopod 1 ( Fig.15A View Figure 15 )similar to male gnathopod 1; carpus 1.4 × longer than wide, without comb-scales, posterior lobe with pectinate margin, with several serrate setae;propodus 1.5 × longer than wide, hammer-shaped, with comb-scales, palm 0.7 × size of posterior margin of propodus, without comb-scales, inner margin with 11 papposerrate setae, palm slope transverse, dactylus claw-like, with comb-scales.

Gnathopod 2 ( Fig. 15B View Figure 15 ) similar in size and shape to gnathopod 1; carpus similar to gnathopod 1; propodus 1.4 × longer than wide, with polygonal pattern on disto-posterior margin, inner margin with up to 9 papposerrate setae, palm transverse with several long simple setae, without comb-scales; dactylus claw-like, congruent to palm, with 1 plumose seta apically and polygonal pattern on posterior margin.

Telson( Fig. 15C View Figure 15 ) 1.2 × longer than wide, similar in shape to male’s, with up to 9 cuspidate setae with accessory seta asymmetrically distributed apically, and 2 small plumose setae on each side, laterally.

Etymology. The epithet temimina is a recognition of the cave, Temimina II, where the specimens of this new species were collected.

Habitat. Freshwater, hypogean, typical lentic waters, with bottom formed by silt and pebbles. Specimens of Hyalella temimina sp. nov. were found only at cave Teminina II. Despite the absence of specimens in the surface streams, Hyalella temimina sp. nov. does not show troglomorphic traits, and we hypothesize that the new species is troglophilic, similar to Hyalella bocaina sp. nov.

Remarks. Table 1 presents the main morphological features that H. temimina sp. nov. differs from the other 42 species that occur in Brazil. It is a hypogean species with no signs of troglomorphism, having large and pigmented eyes. In this way, it differs from classically troglomorphic species, such as H. caeca , H. spelaea , and H. troglofugia . Hyalella temimina sp. nov. body is smooth, which is different from H. pseudoazteca ; H. temimina sp. nov. has pappose setae and does not have comb-scales on the propodus of male gnathopod 1, while H. longipropodus has serrate setae on the inner face of the propodus and comb scales on propodus of male ganthopod 1. Moreover, H. temimina sp. nov. is characterized by the presence of pappose setae on the inner surface of the propodus of gnathopod 1, which differentiates the new species from H. bala , H. dielaii , and H. montana . Finally, H. temimina sp. nov. is different from Hyalella bocaina sp. nov. because the former has only two teeth on the right mandible incisor, palp of maxilla 1 relatively longer, male gnathopod 1 with polygonal pattern only on the propodus and dactylus, gnathopod 2 with polygonal pattern only on the propodus, and uropod 3 with an apical excavation on the ramus, whereas H. bocaina sp. nov. has six teeth on the right mandible incisor, relatively shorter palp of maxilla 1, and polygonal pattern on the merus and ischium of both male gnathopods, with no excavations on the uropod 3 ramus.

Conservation. We propose for both species, H. bocaina sp. nov. and H. temimina sp. nov., the categorization as vulnerable. Vulnerable (VU) - (D2) = typically, area of occupancy (AOO < 20 km 2) or number of locations (≤ 5) ( ICMBio, 2013). Their populations are restricted to small areas and, similar to other Hyalella species, they are possibly endemic and restricted to the sites, or even micro-basins, where they were collected.