Hyalella warmingi Stebbing, 1899

González, Exequiel R. & Watling, Les, 2003, A new species of Hyalella from Brazil (Crustacea: Amphipoda: Hyalellidae), with redescriptions of three other species in the genus, Journal of Natural History 37 (17), pp. 2045-2076 : 2060-2067

Hyalella warmingi Stebbing, 1899

(figures 12–16)

Hyalella warmingi Stebbing, 1899: 406–407 , figure 32A; Stebbing, 1906: 580; Barnard and Barnard, 1983: 709; Pereira, 1983: 38–45, figures 8–10.

Hyalella (Mesohyalella) warmingi: Bousfield, 1996: 192 .

Type material. Copenhagen Museum, CRU-8614.

Type locality. Lagoa Santa , Minas Gerais State, Brazil (19 ° 38 ∞ S, 43 ° 53 ∞ W).

Material examined. Lagoa Santa, Brazil; Zoological Museum, Copenhagen.

Diagnosis. Body surface smooth. Coxa 4 excavated posteriorly. Eyes pigmented. Antenna 1 shorter than antenna 2. Antenna 2 more than half of body length. Mandible incisor toothed. Maxilla 1 palp short, reaching less than half of the distance between base of palp and tip of setae on outer plate; inner plate slender, with two strong and pappose apical setae. Maxilla 2 inner plate with one strong pappose seta on inner margin. Gnathopod 1 propodus twice as long as maximum width or longer (rectangular), hammer-shaped, inner face with 10 pappose setae, disto-posterior and disto-anterior borders without setose scales. Gnathopod 2 propodus rectangular, elongated, palm shorter than posterior margin, slope oblique, anterior corner with a wide truncated or rounded process. Peraeopods 3 and 4 merus and carpus posterior margin with four clusters of short setae; propodus posterior margin with two to four groups of setae. Uropod 3 peduncle with seven strong distal setae; outer ramus longer than peduncle, proximally twice as wide or less than distally. Telson longer than wide, apically pointed, with two widely spaced, long simple setae, asymmetrically distributed on the apical margin. Sternal gills on peraeonites 2–7.

Female. Gnathopod 1 similar in size, but different in shape to gnathopod 2. Gnathopod 2 different from male gnathopod 2 in shape and smaller, propodus less than twice as long as maximum width, normally subchelate, palm transverse.

Description of male. Size 8.2 mm. Body surface smooth (figure 12). Epimeral plates 1–3 acuminate (figure 13 E). Coxae 1–4 subequal in size and shape, slightly overlapping, acumination in coxae absent. Coxa 1 subequal to coxae 2 and 3. Coxa 3 narrower than coxa 4. Coxa 4 deeper than wide, excavated posteriorly. Coxa 5 posterior lobe deeper than anterior lobe. Coxa 6 anterior lobe small.

Head smaller than first two thoracic segments, typically gammaridean, rostrum absent. Eyes pigmented, small, round, located between insertion of antennae 1 and 2.

Antenna 1 less than half of body length, shorter than antenna 2, longer than peduncle of antenna 2; peduncle same length as head, articles 1 and 2 subequal in length, article 3 the shortest; flagellum of 13 articles, longer than peduncle, basal article not elongated; aesthetascs on flagellum distally beginning at article 5 (figure 14 A1).

Antenna 2 more than half of body length; peduncle slender, longer than head, article 4 shorter than article 5, setal groups on article 4 scarce, setal groups on article 5 abundant; flagellum with 18 articles, longer than articles 1–5 together, basal article slightly elongated (figure 14 A2).

Basic amphipodan mandible (in the sense of Watling, 1993); incisor toothed; left lacinia mobilis with four teeth; setae row on left mandible with three main setae plus accessory setae, right mandible with two main setae plus accessory setae; molar medium-sized, cylindrical, triturative, accessory seta present. Labrum ventral margin slightly rounded to truncate. Lower lip outer lobes rounded without notches or excavations, mandibular projection of outer lobes round (figure 13 Ml, U, L).

Maxilla 1 palp uniarticulate, short, reaching less than half of the distance between base of palp and tip of setae on outer plate, distal setae absent; inner plate slender, smaller than outer plate, with two strong and pappose apical setae; outer plate with nine stout and serrate setae (figure 13 X1r, X1l). Maxilla 2 inner plate subequal in length and more slender than outer plate, one strong pappose seta on inner margin, outer and inner plates with abundant setules (figure 13 X2r).

Maxilliped inner plates apically truncated, with three connate setae, pappose setae apically and medially; outer plates larger than inner plates, apically truncated, apical, medial and facial setae simple; palp longer than outer plate, four articles; article 2 longer than wide, medial margin with long simple setae; article 3 outer distal face with few long simple setae, inner distal face with long plumose setae, inner distal margin with long setae, outer margin with one or two strong and long plumose setae; dactylus unguiform, shorter than third article, distal setae simple and shorter than nail, inner border with setae, distal nail present (figure 13 S).

Gnathopod 1 subchelate; carpus longer than wide, longer and wider than propodus, with strong and wide posterior lobe, produced and forming a scoop-like structure, open to the inside, inner face with four to seven pappose setae, border pectinate and with several pappose setae; propodus length twice or more maximum width (rectangular), hammer-shaped, with no setae on anterior border, inner face with 10 pappose setae, one to five small triangular setae, posterior and anterior distal borders without setose scales, palm with transverse slope, margin convex, posterior distal corner with robust setae; dactylus claw-like, with one to three endal setae, congruent with palm (figure 15 G1).

Gnathopod 2 subchelate; basis posterior margin with one to three groups of setae; merus with less than seven setae on posterior margin, posterior distal margin straight, distal corner pointed; carpus posterior lobe elongated, produced between merus and propodus, border pectinate with several pappose setae; propodus rectangular, elongated, posterior and anterior distal borders without setose scales, palm shorter than posterior margin, slope oblique, margin irregular, bearing several strong short setae, few long setae, and several medium-sized setae; anterior edge with a wide truncated or rounded process, posterior distal corner with strong setae, and with cup for dactyl; dactylus claw-like, congruent with palm, with a few endal setae (figure 15 G2).

Peraeopods 3–7 simple. Peraeopods 3 and 4 merus and carpus posterior margin with four marginal clusters of short setae; propodus posterior margin with two to four groups of setae; dactylus less than half of propodus length. Peraeopods 5–7 all similar in structure and slightly longer successively; dactylus less than half of propodus length. Peraeopod 5 subequal to peraeopod 4, basis posterior lobe deeper than long, smaller than posterior lobe of peraeopod 7, merus with two posterior marginal setae, proximal and distal setae subequal. Peraeopod 6 as long as peraeopod 4, basis posterior lobe deeper than long, similar to posterior lobe of peraeopod 5, and smaller than posterior lobe of peraeopod 7. Peraeopod 7 subequal to peraeopod 6, basis posterior lobe longer than deep (figure 16 P3, P4, P5, P6, P7).

Pleopods not modified; peduncle slender; longest ramus longer than peduncle.

Uropod 1 longer than uropod 2; peduncle longer than rami; rami subequal; inner ramus with three dorsal and six distal setae, two of which being longer, male without curved setae on inner side of the ramus; outer ramus with four dorsal and four distal setae; peduncle setation present (figure 14 R 1).

Uropod 2 rami subequal; inner ramus with three dorsal and five distal setae; outer ramus with three dorsal and four distal setae; peduncle setation present (figure 14 R 2).

Uropod 3 longer than urosomite 3, shorter than peduncle of uropod 1, as long as peduncle of uropod 2; peduncle slender (rectangular), wider than ramus, with seven strong distal and one marginal seta; inner ramus absent; outer ramus uniarticulate, longer than peduncle, proximally twice as wide or less than distally, with five simple, apical slender setae, and one connate seta (figure 15 R 3).

Telson longer than wide, entire, apically pointed, with two widely spaced, long simple setae, asymmetrically distributed on apical margin (figure 15 T).

Coxal gills sac-like, on peraeopods 2–6. Sternal gills tubular, on peraeonites 2–7.

Characters of female that differ from male. Size 6.6 mm. Antenna 1 flagellum with eight articles. Antenna 2 similar in shape to male, flagellum with 15 or more articles. Gnathopod 1 similar in size, but different in shape to gnathopod 2; similar to male gnathopod 1 in size and shape. Gnathopod 2 different from male gnathopod 2 in shape and smaller, propodus length less than twice maximum width, normally subchelate, palm transverse (figure 14 fG1, fG2).

Habitat. Freshwater, epigean, littoral.

Distribution. Lagoa Santa, Minas Gerais State; Gruta Mirasol, Mirasol, Sao Paulo State (20 ° 00 ∞ S, 49 ° 00 ∞ W).

Remarks. Hyalella warmingi was considered to be morphologically very similar to H. meinerti ( Pereira, 1983) . The original descriptions are not very detailed and could lead to some confusion. After examining the type material, several differences became evident. The eyes in H. warmingi are smaller than in H. meinerti ; the gnathopods do not have the heavily setose scales on the articular margins from ischium to propodus; the shape of the propodus in gnathopod 2 in male and female also differs; and the apical setae on the telson are much stronger in H. meinerti . Here we designate, from the syntype series, the figured material as the lectotype (male, 8.2 mm) for this species. The material is deposited in the Zoologisk Museum in Copenhagen, Denmark. The lectotype consists of a vial with the body and 11 permanent slides with the appendages. The rest of the syntype series now become part of the paralectotype series.