Hyalella garyi Marrón-Becerra & Hermoso-Salazar 2022, sp. nov.
Creators: name: Marrón-Becerra, Aurora
name: Hermoso-Salazar, Margarita
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Hyalellidae
Hyalella
Hyalella garyi

description: 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.
description: 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