Gammarus egregius, HOU & LI & LI, 2013

HOU, ZHONGE, LI, JUNBO & LI, SHUQIANG, 2013, Ten new Gammarus species (Crustacea: Amphipoda: Gammaridae) from Yunnan-Guizhou Plateau, China , Zootaxa 3687 (1), pp. 1-95 : 35-43

publication ID	https://doi.org/ 10.11646/zootaxa.3687.1.1
publication LSID	lsid:zoobank.org:pub:193BA226-D0D0-42C9-9815-639E8E48EF7A
DOI	https://doi.org/10.5281/zenodo.10540390
persistent identifier	https://treatment.plazi.org/id/5D2BDE76-FFEF-710B-FF54-FF26FE9FFCFF
treatment provided by	Felipe
scientific name	Gammarus egregius
status	sp. nov.

Treatment

Gammarus egregius sp. nov.

Figs 3A View FIGURE 3 , 24–29 View FIGURE 24 View FIGURE 25 View FIGURE 26 View FIGURE 27 View FIGURE 28 View FIGURE 29

Material examined. Holotype: male (IZCAS-I-A1107-1), 9.8 mm, from Sandie Spring, (100.77 °E, 27.52°N), altitude 2,662 m, Biyi Valley , Ninglang County, Lijiang City, Yunnan Province, China, July 7, 2010, collected by C. Wang and L. Lin. GoogleMaps Paratype: 1 female (IZCAS-I-A1107-2), 9.2 mm, same data as holotype GoogleMaps .

Etymology. The specific name is from Latin egregius (famous), in reference to this species are found in a beautiful scenic area; adjective.

Diagnosis. Inner plates of maxilla I and II with fewer plumose setae; urosome segment I dorsally bare, urosome segment II with 2 single spines on dorsal margin, urosome segment III with 2 spines accompanied by 1 seta on each side and 2 clusters of 2 setae on dorsal margin; inner ramus of uropod III reaching 0.6 times the length of outer ramus, with clusters of simple setae on each margin.

Description of male. Holotype (IZCAS-I-A1107-1), male 9.8 mm ( Fig. 3A View FIGURE 3 ).

Head ( Fig. 24A View FIGURE 24 ): eyes oval, 1.4 times as long as wide, inferior antennal sinus deep, lateral cephalic lobe nearly straight.

Antenna I ( Fig. 24B, C View FIGURE 24 ): 1 st to 3 rd article of peduncle in length ratio 1.0: 0.7: 0.5, with setae on distal corner; flagellum with 23 articles, 4 th to 22 nd article with aesthetascs; accessory flagellum with 4 articles; both primary and accessory flagella with short distal setae.

Antenna II ( Fig. 24D View FIGURE 24 ): about 0.8 times as long as antenna I, 3 rd to 5 th article of peduncle in length ratio 1.0: 3.2: 3.2, 4 th and 5 th article of peduncle with 5–6 clusters of lateral and medial setae; flagellum with 7 articles and 1 tiny distal article, with setae along dorsal and ventral margins; calceoli absent.

Upper lip ( Fig. 24E View FIGURE 24 ): ventral margin rounded, bearing minute setae.

Mandible ( Fig. 24G, H View FIGURE 24 ): left mandible incisor with 5 teeth; lacinia mobilis with 4 teeth, spine row with 4 pairs of plumose setae along ventral margin; 1 st to 3 rd article of palp in length ratio 1.0: 3.2: 3.2, 2 nd article of palp armed with 15 marginal setae, 3 rd article with a row of 4 A-setae, 2 clusters of B-setae, 20 D-setae and 5 E-setae apically; incisor of right mandible with 4 teeth, lacinia mobilis bifurcate, with small teeth.

Lower lip ( Fig. 24F View FIGURE 24 ): inner lobes lacking, outer lobes covered with thin setae.

Maxilla I ( Fig. 24I, J View FIGURE 24 ): asymmetrical, left inner plate with 10 plumose setae on medial margin; outer plate with 11 robust serrated apical spines, each spine with small teeth; 2 nd article of palp with 9 slender spines and 2 stiff setae apically; 2 nd article of right palp with 5 stout spines, 1 stiff seta and 1 slender spine.

Maxilla II ( Fig. 24K View FIGURE 24 ): inner plate with 8 plumose facial setae in an oblique row; inner and outer plates with long setae apically.

Maxilliped ( Fig. 24L View FIGURE 24 ): inner plate with 1 subapical and 3 stout apical spines, some plumose setae along ventral margin; outer plate bearing a row of blade spines and 3 plumose setae apically; 4 th article of palp hooked, with a group of setae at hinge of unguis.

Gnathopod I ( Fig. 25A, C View FIGURE 25 ): coxal plate bearing 6 setae and 1 seta on anterior and posterior margins, respectively; basis with setae on anterior and posterior margins; carpus 1.8 times as long as wide, about 0.8 times as long as propodus, posterior margin bearing short setae; propodus oval, palm with 1 medial spine and 9 spines on posterior margin and surface; dactylus with 1 seta on outer margin.

Gnathopod II ( Fig. 25B, D View FIGURE 25 ): coxal plate bearing 3 setae and 1 seta on anterior and posterior margins; basis with setae on anterior and posterior margins, posterodistal corner with short setae; carpus 1.8 times as long as wide, carpus as long as propodus, with parallel margins, bearing 7 clusters of setae along ventral margin, 2 clusters of setae on dorsal margin; propodus subrectangular, palm margin with 1 medial spine and 4 spines on posterodistal corner; dactylus with 1 seta on outer margin.

Pereopod III ( Fig. 26A, F View FIGURE 26 ): coxal plate bearing 5 setae and 1 seta on anterior and posterior margins; basis elongate, with setae along anterior and posterior margins; merus with clusters of setae on posterior margin, anterodistal corner with 1 spine accompanied by setae; carpus and propodus with groups of spines accompanied by setae on posterior margin; dactylus with 1 plumose seta on posterior margin, and 2 setae at hinge of unguis.

Pereopod IV ( Fig. 26B, G View FIGURE 26 ): coxal plate excavated, bearing 4 setae on anterior margin and 9 setae on posterior margin; basis with some simple setae along posterior margin; merus with clusters of setae on posterior margin and 2 tiny setae on anterior margin, anterodistal with 1 spine accompanied by some setae; carpus and propodus with groups of spines accompanied by setae on posterior margin; dactylus with 1 plumose seta on anterior margin, and 2 setae at hinge of unguis.

Pereopod V ( Fig. 26C, H View FIGURE 26 ): coxal plate bearing 4 setae on posterior margin; basis with 2 setae and 4 spines on anterior margin, anterodistal corner with 1 spine accompanied by some setae, posterior margin with a row of 12 setae; merus with 4 and 1 cluster of tiny setae on anterior and posterior margins, anterodistal and posterodistal corners with 2 spines respectively; carpus and propodus with groups of spines on anterior margin; dactylus with 1 plumose seta on posterior margin, and 2 setae at hinge of unguis.

Pereopod VI ( Fig. 26D, I View FIGURE 26 ): coxal plate bearing 3 setae on posterior margin; basis elongate, with 4 setae and 3 spines on anterior margin, anterodistal corner with 1 spine accompanied by some setae, posterior margin dwindling distally, with a row of 11 setae; merus to propodus with groups of spines on anterior margin; dactylus with 1 plumose seta on posterior margin, and 2 setae at hinge of unguis.

Pereopod VII ( Fig. 26E, J View FIGURE 26 ): coxal plate bearing 4 setae on posterior margin; basis expanded, posterior margin weakly narrowed distally, anterior with 2 setae and 3 spines, anterodistal corner with 1 spine, inner surface with 1 spine, posterior with a row of 19 setae; merus to propodus with groups of spines on anterior margin; dactylus with 1 plumose seta on posterior margin, and 2 setae at hinge of unguis.

Coxal gills: coxal gill of gnathopod II and gills of pereopods III–V a little shorter than bases; gill of pereopod VI more than half the length of basis; gill of pereopod VII smallest, less than half of basis.

Epimeral plates ( Fig. 27B–D View FIGURE 27 ): plate I ventrally rounded, bearing 5 long setae and 3 short setae on anteroventral margin, with 7 setae on posterior margin; plate II with 3 setae and 1 spine on ventral margin, with 9 setae on posterior margin, posterodistal corner blunt; plate III with 3 spines on ventral margin and 9 setae on posterior margin, posterodistal corner blunt.

Pleopods I–III ( Fig. 27E–G View FIGURE 27 ): similar, peduncle with 1–2 retinacula accompanied by 1–2 setae; outer ramus slightly longer than inner ramus, both rami fringed with plumose setae.

Urosome ( Figs 25E View FIGURE 25 , 27A View FIGURE 27 ): dorsally flat. Urosome segment I dorsally bare. Urosome segment II with 2 single spines on dorsal margin. Urosome segment III with 2 spines accompanied by 1 seta on each side and 2 clusters of 2 setae on dorsal margin.

Uropods I–III ( Fig. 27H–J View FIGURE 27 ): uropod I peduncle without basofacial spine, with 2 spines on outer margin, 2 and 1 spine on outer and inner corners; outer ramus with 1 spine on inner margin; inner ramus with 2 spines on inner margin; both rami with 5 terminal spines. Uropod II short, peduncle bearing 1 spine on outer and inner margins respectively, with 1 distal spine on each corner; inner ramus with 1 spine on outer and inner margins; outer ramus shorter than inner ramus, with 1 spine on inner margin; both rami with 5 terminal spines. Uropod III peduncle with 5 distal spines; inner ramus about 1.1 times as long as peduncle, 0.6 times as long as outer ramus, outer margin with 1 spine accompanied by 1 seta and 2 clusters of simple setae, bearing 2 apical spines accompanied by 5 simple setae; 1 st article of outer ramus with 2 pairs of spines accompanied by simple setae on outer margin, inner margin with 4 clusters of simple setae; terminal article shorter than adjacent spines.

Telson ( Fig. 27K View FIGURE 27 ): deeply cleft, 0.8 times as long as wide, left lobe with 2 spines and right lobe with 3 spines, both lobes with 1 cluster of 1 single seta accompanied by 1 plumose seta apically.

Description of female. Paratype (IZCAS-I-A1107-2), 9.2 mm.

Gnathopod I ( Fig. 28A, C View FIGURE 28 ): coxal plate bearing 3 fine setae and 1 seta on anterior and posterior margins, respectively; basis with setae on anterior and posterior margins; propodus oval, palm with 3 spines on posterior margin.

Gnathopod II ( Fig. 28B, D View FIGURE 28 ): coxal plate bearing 4 setae and 1 seta on anterior and posterior margins; basis with setae on anterior and posterior margins, posterodistal corner with short setae; propodus subrectangular, palm margin with 4 spines on posterodistal corner, bearing simple setae along anterior and posterior margins; dactylus with 1 seta on outer margin.

Pereopods III and IV ( Fig. 29A–B, F–G View FIGURE 29 ): with fewer straight setae on posterior margins than those of male.

Pereopods V–VII ( Fig. 29C–E, H–J View FIGURE 29 ): merus with more setae on anterior margins than those of male.

Uropods I–III ( Fig. 27L–N View FIGURE 27 ): uropod I peduncle without basofacial spine, with 2 and 1 spine on outer and inner margins, with 2 and 1 spine on each corner; inner ramus with 1 spine on inner margin; outer ramus with 1 spine on inner and outer margins; both rami with 5 terminal spines. Uropod II short, peduncle bearing 1 spine on outer margin, with 1 distal spine on each corner; inner ramus with 1 spine on inner margin, outer ramus with 1 spine on outer margin; both rami with 5 terminal spines. Uropod III peduncle with 5 distal spines; inner ramus 0.8 times as long as peduncle, reaching 0.5 times the length of outer ramus, with 1 spine accompanied by 1 seta on lateral margin; 1 st article of outer ramus with 2 spines accompanied by setae on outer margin; terminal article short than adjacent spines.

Telson ( Fig. 28I View FIGURE 28 ): cleft, both lobes with 2 spines accompanied by 2 simple setae and 1 plumose seta.

Oostegite ( Fig. 28E–H View FIGURE 28 ): oostegite of gnathopod II broad, with marginal setae, oostegite of pereopods III and IV elongate, oostegite of pereopod V smallest.

Variability. The variability pattern is similar to G. pulex pattern ( Karaman & Pinkster 1977), telson with few or without dorsal setae.

Habitat. Specimens were collected along a small brook from Sandie Spring. The Sandie Spring means there are three springs in different height, the highest spring for drinking, the middle one for washing vegetable, and the lowest one for washing clothes.

Remarks. Gammarus egregius sp. nov. can be distinguished from G. lophacanthus Hou & Li, 2002 by the following characters ( G. lophacanthus in parentheses): urosome segment I dorsally bare, urosome segment II with 2 spines on dorsal margin, urosome segment III with 2 pairs of spines accompanied by 1 seta and 2 clusters of 2 setae on dorsal margin (urosome segments I and II with 1 cluster of 3–4 spines on dorsal margin medially; urosome segment III with 2-1-1-2 spines on dorsal margin); epimeral plates I–III with more setae on posterior margins (with fewer setae); inner ramus of uropod III reaching 0.6 times the length of outer ramus, with clusters of simple setae on each margins (reaching 0.8 times the length of outer ramus, with fewer setae); telson 0.8 times as long as wide (longer than wide).