Gammarus eliquatus, 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 : 43-51

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.10540392
persistent identifier	https://treatment.plazi.org/id/5D2BDE76-FFE7-7113-FF54-FC35FC45FAD4
treatment provided by	Felipe
scientific name	Gammarus eliquatus
status	sp. nov.

Treatment

Gammarus eliquatus sp. nov.

Figs 3B View FIGURE 3 , 30–35 View FIGURE 30 View FIGURE 31 View FIGURE 32 View FIGURE 33 View FIGURE 34 View FIGURE 35

Material examined. Holotype: male (IZCAS-I-A1074-1), 10.2 mm, Wenquan Village , Xiaguan Town (100.03°E, 25.65°N), altitude 1,688 m, Dali City, Yunnan Province, China, February 6, 2010, collected by L. Lin and H. Pu. GoogleMaps Paratype: 1 female (IZCAS-I-A1074-2), 7.1 mm, same data as holotype GoogleMaps .

Etymology. The specific name is from Latin eliquatus (clear), in reference to the habitat of this species; adjective.

Diagnosis. Antenna II densely with long setae on 4 th and 5 th article of pecuncle and flagellum; pereopod III with long setae from merus to propodus; inner ramus of uropod III reaching about 0.6 times the length of outer ramus, all margins with long simple setae and plumose setae; telson with long setae on each lobe.

Description of male. Holotype (IZCAS-I-A1074-1), male 10.2 mm ( Fig. 3B View FIGURE 3 ).

Head ( Fig. 30A View FIGURE 30 ): eyes reniform, 1.8 times as long as wide, inferior antennal sinus deep, lateral cephalic lobe nearly straight.

Antenna I ( Fig. 30B, C View FIGURE 30 ): 1 st to 3 rd article of peduncle in length ratio 1.0: 0.6: 0.5, with setae on distal corner; flagellum with 23 articles, 4 th to 20 th article with aesthetascs; accessory flagellum with 3 articles; both primary and accessory flagella with short distal setae.

Antenna II ( Fig. 30D–F View FIGURE 30 ): about 0.7 times as long as antenna I, 3 rd to 5 th article of peduncle in length ratio 1.0: 3.0: 4.1, 4 th and 5 th article of peduncle with 4–5 clusters of lateral and medial setae; flagellum with 9 articles and 1 tiny distal article, densely with long setae along dorsal and ventral margins; calceoli absent.

Upper lip ( Fig. 30G View FIGURE 30 ): ventral margin rounded, bearing minute setae.

Mandible ( Fig. 30I, J View FIGURE 30 ): left mandible incisor with 5 teeth; lacinia mobilis with 4 teeth; 1 st to 3 rd article of palp in length ratio 1.0: 2.8: 2.2, 2 nd article of palp armed with 14 marginal setae, 3 rd article with 4 A-setae, 4 B-setae, 17 D-setae and 5 E-setae apically; incisor of right mandible with 4 teeth, lacinia mobilis bifurcate, with small teeth.

Lower lip ( Fig. 30H View FIGURE 30 ): inner lobes lacking, outer lobes covered with thin setae.

Maxilla I ( Fig. 30K, L View FIGURE 30 ): asymmetrical, left inner plate with 13 plumose setae on medial margin; outer plate with 11 robust serrated apical spines, each spine with small teeth; 2 nd article of palp with 8 slender spines and 2 stiff setae apically; 2 nd article of right palp with 5 stout spines and 1 slender spine.

Maxilla II ( Fig. 30M View FIGURE 30 ): inner plate with 12 plumose setae in an oblique row; inner and outer plates with long setae apically.

Maxilliped ( Fig. 30N View FIGURE 30 ): inner plate with 1 subapical and 3 stout apical spines, some plumose setae along lateral 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. 31A, C View FIGURE 31 ): coxal plate bearing 3 setae and 1 seta on anterior and posterior margins; basis with setae on posterior margin; carpus 1.4 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 11 spines on posterior margin and surface.

Gnathopod II ( Fig. 31B, D View FIGURE 31 ): 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; merus bearing some long setae on posterior margin; carpus 1.6 times as long as wide, about 0.8 times as long as propodus, with parallel margins, bearing 9 clusters of setae along ventral margin; propodus subrectangular, palm margin with 1 medial spine and 7 spines on posterodistal corner; dactylus with 1 seta on outer margin.

Pereopod III ( Fig. 32A, F View FIGURE 32 ): coxal plate bearing 2 setae and 1 seta on anteroventral and posterior margins; basis elongate, with setae along anterior and posterior margins; merus densely set with long setae on posterior margin and 2 spines accompanied by setae on anterior margin, anterodistal corner with some 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. 32B, G View FIGURE 32 ): coxal plate excavated, bearing 3 setae on anteroventral corner and 6 setae on posterior margin; basis with setae on anteroventral margin and some long setae on posterior margin; merus with clusters of long setae on posterior margin and 1 spine accompanied by 1 seta on anterior margin, anterodistal 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 anterior margin, and 2 setae at hinge of unguis.

Pereopod V ( Fig. 32C, H View FIGURE 32 ): coxal plate bearing 1 seta on anterior margin and 3 fine setae on posterior margin; basis expanded, with 3 simple setae and 1 spine on anterior margin, anterodistal corner with 1 spine, posterior margin with a row of 8 setae; merus to propodus with groups of spines accompanied by setae on anterior margin; dactylus with 1 plumose seta on posterior margin, and 2 setae at hinge of unguis.

Pereopod VI ( Fig. 32D, I View FIGURE 32 ): coxal plate bearing 1 seta on anterior margin and 3 setae on posterior margin; basis elongate, with 4 simple setae and 3 spines on anterior margin, anterodistal corner with 1 spine, posterior margin dwindling distally, with a row of 11 setae; merus to propodus with groups of spines accompanied by setae on anterior margin; dactylus with 1 plumose seta on posterior margin, and 2 setae at hinge of unguis.

Pereopod VII ( Fig. 32E, J View FIGURE 32 ): coxal plate bearing 6 setae on posterior margin; basis expanded, posterior margin weakly narrowed distally, anterior with 3 simple setae and 3 spines, inner surface with 3 setae, posterior with a row of 13 setae; merus to propodus with groups of spines accompanied by setae 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. 31E–G View FIGURE 31 ): plate I ventrally rounded, bearing 4 longer setae and 3 shorter setae on anteroventral margin, with 7 setae on posterior margin; plate II with 2 spines and 2 tiny setae on ventral margin and 7 setae on posterior margin, posterodistal corner subacute; plate III with 2 spines and 3 simple setae on ventral margin, and 6 setae on posterior margin, posterodistal corner subacute.

Pleopods I–III ( Fig. 33B–D View FIGURE 33 ): similar, peduncle with 1–2 retinacula accompanied by 2–3 setae; outer ramus slightly longer than inner ramus, both inner and outer rami fringed with plumose setae.

Urosome ( Fig. 33A View FIGURE 33 ): dorsally flat. Urosome segment I with 2 clusters of 1 spine accompanied by setae on dorsal margin, with 1 spine accompanied by setae and 1 cluster of setae on left and right sides, respectively; urosome segment II with 1-2-1 spines accompanied by setae on dorsal margin; urosome segment III with 1 spine and clusters of setae on dorsal margin.

Uropods I–III ( Fig. 33E–G View FIGURE 33 ): uropod I peduncle with 1 basofacial spine, 2 spines on outer and inner margins, 2 and 1 spine on each corner; outer ramus with 1 spine on outer and inner margins; inner ramus with 2 spines on inner margin, both rami with 5 terminal spines. Uropod II short, peduncle bearing 1 spine on outer margin, 1 distal spine on each corner; inner ramus with 2 spines on inner margin, outer ramus with 1 spine on inner margin; both rami with 5 terminal spines. Uropod III peduncle with setae on lateral margin and 3 distal spines; inner ramus about 2 times as long as peduncle, reaching 0.6 times the length of outer ramus, with long simple setae on inner margin and 2 distal spines accompanied by long setae; 1 st article of outer ramus with 2 spines accompanied by long simple setae on outer margin, inner margin densely set with long setae and few plumose setae; terminal article slightly shorter than adjacent spines.

Telson ( Fig. 33H View FIGURE 33 ): deeply cleft, about 1.2 times as long as wide, both lobes with 2 clusters of long setae on dorsolateral margins, bearing 1 apical spine accompanied by 6 long setae.

Description of female. Paratype (IZCAS-I-A1074-2), 7.1 mm.

Gnathopod I ( Fig. 34A, C View FIGURE 34 ): coxal plate bearing 2 fine setae on anteroventral and posterior margins respectively; basis with long setae on posterior margin; propodus oval, palm with 12 spines on posterior margin.

Gnathopod II ( Fig. 34B, D View FIGURE 34 ): coxal plate bearing 3 fine setae and 1 seta on anteroventral and posterior margins; basis with long setae on posterior margin, 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. 35A–B, F–G View FIGURE 35 ): with fewer straight setae on posterior margin than those of male.

Pereopods V–VII ( Fig. 35C–E, H–J View FIGURE 35 ): similar to those of male, merus to propodus with spines accompanied by more setae.

Uropods I–III ( Fig. 33I–K View FIGURE 33 ): uropod I peduncle with 1 basofacial spine, 2 spines on outer margin and 1 spine on inner margin, with 1 spine on outer distal corner; both rami with 5 terminal spines. Uropod II short, peduncle bearing 1 spine on outer margin; each ramus with 1 spine on outer margin and 5 terminal spines. Uropod III peduncle with 5 distal spines and some setae; inner ramus 1.2 times as long as peduncle, reaching 0.6 times the length of outer ramus, with some long setae on lateral margin; 1 st article of outer ramus with 2 spines accompanied by long setae on outer margin, both margins densely set with simple setae; terminal article slightly shorter than adjacent spines.

Telson ( Fig. 34I View FIGURE 34 ): cleft, 0.8 times as long as wide, each lobe with long setae on dorsolateral margins and with 2 spines accompanied by long setae apically.

Oostegite ( Fig. 34E–H View FIGURE 34 ): oostegite of gnathopod II broad, with marginal setae, oostegites of pereopods III and IV elongate, oostegite of pereopod V smallest.

Variability. The ratio of length to width for telson various from 0.8 to 1.2; the setation on dorsal margin of urosome segment III various with 1 or 2 spines accompanied by several groups of setae.

Habitat. This species was collected from a warm spring and the species is known only from the type locality ( Fig. 1 View FIGURE 1 ).

Remarks. Gammarus eliquatus sp. nov. can be distinguished from G. stagnarius Hou, Li & Morino, 2003 by the following characters ( G. stagnarius in parentheses): 3 rd article of mandible palp with 17 D-setae (25 D-setae); antenna II with groups of long setae (short setae); inner ramus of uropod III about 0.6 times the length of outer ramus, outer margin with long simple setae (0.6 times of outer ramus; all margins with plumose setae); both lobes of telson with long setae (short setae); epimeral plates subacute (acute).