Hyalella viviannae, Marrón-Becerra & Hermoso-Salazar, 2022

Marrón-Becerra, Aurora & Hermoso-Salazar, Margarita, 2022, Morphological comparison and description of five new species of Hyalella (Crustacea: Amphipoda) from Veracruz and Mexico City, Journal of Natural History 56 (25 - 28), pp. 1215-1263 : 1232-1238

publication ID	https://doi.org/ 10.1080/00222933.2022.2078241
publication LSID	lsid:zoobank.org:pub:9DF27EA5-D5DD-4010-9092-CB6BB358E6B7
DOI	https://doi.org/10.5281/zenodo.7102149
persistent identifier	https://treatment.plazi.org/id/0207BC20-8C5B-7B5B-CBCC-FDE54E53F971
treatment provided by	Plazi
scientific name	Hyalella viviannae
status	sp. nov.

Treatment

Hyalella viviannae sp. nov.

http://www.zoobank.org/ urn:lsid:zoobank.org:act:340959E3-C21D-4170-A8A2-85E21305C032

( Figures 8–10 View Figure 8 View Figure 9 View Figure 10 )

Etymology. The new species is named in honour of Dra Vivianne Solís-Weiss, in recognition of her studies of marine and estuarine invertebrates in Mexico.

Material examined. Holotype male, size 4.9 mm (Cat. No. CNCR 35728 ) from Lake San Julian , state of Veracruz, Mexico (19.256°N, 96.265°W), 24 July 2015, 5 m. a.s.l., temp. 37°C, pH 7.8. Collectors: A. Marrón-Becerra, E. Lemus-Santana and M. Hermoso-Salazar. GoogleMaps Paratypes (n = 30 males, n = 30 females): males – mean size 4.5 ± 0.6 mm (n = 27), mean head length 0.6 ± 0.03 mm (n = 10), females – mean size 4.3 ± 0.4 mm, mean head length 0.6 ± 0.03 (n = 30) (permanent slides Cat. No. CNCR 35737 , paratypes and SEM preparations CNCR 35738 ), locality same as holotype GoogleMaps .

Type locality ( Figure 1b View Figure 1 ). Lake San Julian GoogleMaps , state of Veracruz, Mexico (19.256°N, 96.265° 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 tip of setae in outer plate, with 1 large 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 4 serrate setae, comb scales on distoposterior and distoanterior border, carpus inner face lobe with 3 serrate setae. Gnathopod 2, basis hind margin with 2 serrate setae. Uropods without curved setae. Uropod 3, peduncle slightly shorter than ramus, ramus styliform. Telson slightly longer than width, distal margin rounded with 2 long simple apposed setae. Coxal gills on segments 2–6. Sternal gills on segments 3–7.

Description of male

Body ( Figures 8a View Figure 8 , and 17e View Figure 17 ), tergites of pleon 1 and 2 with dorsoposterior carina. Epimeral plates 1–3 slightly acuminate. Coxae 1–3 ( Figures 8a View Figure 8 , and 17e View Figure 17 ) subequal in shape, subrectangular, longer than wide; coxa 4 wider than coxae 1–3 with deep posterior excavation; acumination absent. coxa 5 anterior lobe slightly shorter than posterior; coxa 6 anterior lobe reduced; coxa 7 anterior lobe absent.

Head typically gammaridean ( Figures 8a View Figure 8 , and 17e View Figure 17 ), shorter than first two thoracic segments, rostrum absent. Eyes pigmented, medium, rounded, located between insertions of antennae 1 and 2.

Antenna 1 ( Figure 8a–b View Figure 8 ) less than half body length, shorter than antenna 2, but longer than peduncle of antenna 2; peduncle longer than head, almost reaching second pereonite; articles 1 and 2 subequal in length, article 1 wider than articles 2–3, article 2 longer and wider than article 3 (proportions 1.6:1.3:1), article 1 almost reaching half ventral surface with 1 short cuspidate seta and with one cluster with 3 cuspidate setae at ventral-distal end, articles 2–3 without mid-ventral margin setae; flagellum longer than peduncle with 6 articles gradually shorter towards distal portion; aesthetascs present on articles 3–5 (one).

Antenna 2 ( Figure 8a, c View Figure 8 ) almost 1.2 times longer than antenna 1, reaching one-third body length, almost reaching fifth pereonite; peduncle almost reaching the second 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 (less than 1.5 times); flagellum with 7–9 articles, slightly longer than peduncle (almost 1.5 times); without aesthetascs.

Buccal parts: upper lip ( Figure 8f View Figure 8 ) distal margin rounded with numerous setules.

Lower lip ( Figure 8g View Figure 8 ), subquadrate, outer lobes without notches or excavations, mandibular projection of outer lobes rounded.

Mandibles ( Figure 8h–i View Figure 8 ), 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-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 ( Figure 8d View Figure 8 and 19d View Figure 19 ), palp uniarticulate, longer than wide, distally pointed with 1 stout distal seta, seta length reaching one-third of palp length, setules present; palp length almost reach 2/3 of distance between base of palp and base of seta on outer plate, almost half distance between base of palp and tip of seta on outer plate ( Figure 8d View Figure 8 ); inner plate slender, shorter than outer plate with 2–3 pappose distal setae; outer plate with 9 stout distal serrate setae and with setules ( Figure 8d View Figure 8 ).

Maxilla 2 ( Figure 8e View Figure 8 ) plates subequal; inner plate shorter and slender, with 2 pappose setae on mid-distal margin, and with 7 shorter paposerrate setae; outer and inner plates with large simple distal setae (A 2 type) and abundant setules on both distal surfaces and margins.

Maxilliped ( Figures 8j View Figure 8 , and 20d View Figure 20 ) 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 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, outer margin with 4 simple setae and comb scales, inner margin with 5–6 setae and at least 9 at distal end; fourth article unguiform, longer than nail, with comb scales, inner margin near distal half with 3 setae and 1 near nail base on outer margin; nail exceeds 2/3 of fourth article, with serration at distal half.

Gnathopod 1 ( Figure 9a View Figure 9 ) 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 4 setae. Ischium short, subquadrate; distal posterior end with two clusters of 2 setae. Merus longer than wide, ventral surface with comb scales; distal margin with 5 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; lobe inner surface with 3 serrate setae. Propodus maximum length less than 1.5 times longer than wide; inner surface near distal margin with 4 serrate setae in one row, distal anterior end with one cluster of approximately 7 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 9b View Figure 9 , and 21d View Figure 21 ) subchelated; palm slightly oblique. Basis elongate, more than 3 times longer than wide; posterior margin with 1–2 setae. Ischium short, subquadrate, shorter than merus. Merus short, posterior margin with 8 simple setae; distal third of posterior inner and outer surfaces with comb scales. Carpus shorter than propodus; anterodistal end with 3 setae; posterior lobe scoop-like, elongate, with several submarginal pappose setae and comb scales. Propodus robust, length slightly exceeds 1.5 times as long as wide (1.6 times), subrectangular; palm slightly shorter than posterior margin; slope slightly irregular, with several long simple setae, and few and médium setae; inner face with 4 submarginal thinner simple setae; palm, distal margin, with one truncated process near insertion of dactylus, and without posterior excavation at base, angle stepped ( Figure 22d View Figure 22 ); 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 proximal third with one plumose seta, inner margin crenulate with separated setae.

Pereopods 3–7 ( Figure 9e–i View Figure 9 ) simple, gradually longer posteriorly. Pereopod 5 shorter than 4 and 6.

Pereopod 3 ( Figure 9e View Figure 9 ), basis elongate, mid-posterior margin with 1 simple seta. Merus; anterior margin with 2 setae; posterior margin with 4 setae, anterodistal end with one cluster of 2 setae and posterodistal end with one cluster of 4–5 setae. Carpus shorter and slenderer than merus; posterior margin with 4 stout setae plus accessory setae; posterodistal end with at least 4 slender setae; anterodistal end with at least 2 setae. Propodus shorter than posterior margin of merus; posterior margin with 4 setae; anterodistal end with 5 simple setae. Dactylus claw-like, length almost half of length of propodus; nail present.

Pereopod 4 ( Figure 9f View Figure 9 ) 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 seta; propodus posterior margin with 5 stout setae.

Pereopods 5–7 ( Figure 9g –i View Figure 9 ) similar in shape, basis posterior lobe rounded and denticulated. Pereopod 7 ( Figure 9i View Figure 9 ) 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 width as basis (measured at cleft between basis and basis lobe); posterior margin with 15 serrations, each with 1 setule (13) but 2 serrations with 1 stout seta on distal margin; anterior margin, distal end with three clusters of stout setae on distal half and one cluster of 3 stout setae at distal end. Dactylus length almost half of propodus length.

Pleopods 1–3 ( Figure 10e View Figure 10 ) 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 10a View Figure 10 ) longer than uropod 2; peduncle longer than rami, dorsal margin with 3 dorsal setae, 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; male without curved setae on inner ramus.

Uropod 2 ( Figure 10b View Figure 10 ) slightly longer than peduncle of uropod 1; peduncle as long as outer ramus, with 1 dorsal seta and 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 10c View Figure 10 , and 23d View Figure 23 ) length similar to peduncle of uropod 2; peduncle rectangular, wider than ramus, with 4 strong distal setae of variable length; inner ramus absent; outer ramus uniarticulate, slender, slightly longer than peduncle, more than 2 times (almost 3 times) length of larger setae of peduncle, basal width near 3 times width of apex of ramus, with 3 slender apical setae and 1 connate seta.

Telson ( Figures 10d View Figure 10 , and 24d View Figure 24 ) entire, longer than wide, narrowing posteriorly, with 2 long simple apposed setae; outer surface 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 17f View Figure 17 ) similar to male. Gnathopod 1 ( Figure 9c View Figure 9 ), carpus with 2 serrate setae on inner face lobe; propodus with 3 serrate setae in a row over the inner face. Gnathopod 2 ( Figure 9d View Figure 9 ) smaller than male gnathopod 2, parachelated; palm reverse oblique; basis posterior margin with 1 seta; propodus slightly longer than twice maximum width, outer face with 2 serrate setae in a row and 1 large seta near the palm; anterior and posterior distal half with comb scales. Pereonite 2 with an anterior excavation or notch for amplexus. Pereopod 7 lobes with 10 serrations and setules, and with 3 stout setae on the distal margin. Oostegites subtriangular with setae curled on the margins.

Intraspecific variation. The palp of maxilla 1 is short but presents differences in length and form; especially if the organism is moulting, it could reach almost 2 times its length and present a constricted margin in the middle.

Habitat. Freshwater, epigean, littoral, associated with roots of Typha dominguensis Pers , found in the sediment.

Distribution. Lake San Julian, state of Veracruz, Mexico (19.256°N, 96.265°W).

Remarks

Hyalella viviannae sp. nov. is similar to H. azteca and the other species from state of Veracruz; however, this species can be recognised by the relatively long distal seta in the palp of maxilla 1, the absence of one notch in the palm of gnathopod 2 in males (angle step), the relative length of the ramus in uropod 3 (longer than peduncle), and the form of the telson – longer than wide with 2 apposed setae and the distal margin rounded.)