Gammarus zhouqiongi, Zhang & Wang & Ge & Ma & Zhou, 2022

Zhang, Kui, Wang, Jun, Ge, Yihao, Ma, Jishun & Zhou, Qiong, 2022, A new Gammarus species from Xinjiang Uygur Autonomous Region (China) with a key to Xinjiang freshwater gammarids (Crustacea, Amphipoda, Gammaridae), ZooKeys 1090, pp. 129-147 : 129

Gammarus zhouqiongi sp. nov.

Figs 4 , 5 , 6 , 7 , 8 , 9 , 10

Material examined.

Holotype: male (GAHBH-001), 14.9 mm, Habahe County (48.08°N, 86.35°E), altitude 528 m, Xinjiang Uygur Autonomous Region , China, October 16, 2020, collected by Kui Zhang. Paratypes: female (GAHBH-002), 12.3 mm; five males and three females (GAHBH003-010), same data as holotype . three males and two females (GAKLY001-005), Emin County (46.76°N, 84.42°E), altitude 991 m, Xinjiang Uygur Autonomous Region , China, July 12, 2015, collected by Jun Wang and Yihao Ge.

Etymology.

The specific name was to thank Professor Zhou for funding this study.

Diagnosis.

Peduncle articles IV-V of antenna II with clusters of short setae; merus to carpus of pereopod III with clusters of long setae that exceed the width of the underlying segment on posterior margins; epimeral plates III with subacute posterodistal corners; inner ramus of uropod III more than twice times as long as peduncle, reaching 0.7 times the length of outer ramus, both inner and outer margins of inner ramus and the inner margins of outer ramus with plumose setae, and outer margin of outer ramus with long simple setae.

Description of male holotype.

(GAHBH-001), 14.9 mm.

Head. (Fig. 5A ): eyes reniform, inferior antennal sinus deep.

Antenna I (Fig. 5B, C ): peduncle articles I-III in length ratio 1.0: 0.7: 0.4 bearing short setae; flagellum with 30 articles, most with aesthetascs; accessory flagellum with five articles; both primary and accessory flagella bearing small setae distally.

Antenna II (Fig. 5D, E ): peduncle articles III-V in length ratio 1.0: 3.0: 2.9, peduncle article III with lateral setae, articles IV and V of peduncle with clusters of lateral and medial setae; flagellum with 14 articles, each article with setae along ventral margins; articles II-VI with calceoli.

Upper lip (Fig. 5F ): ventral margin rounded, with minute setae on the distal part.

Mandible (Fig. 5H, I ): left mandible incisor with five teeth; lacinia mobilis with four teeth; spine row with five pairs of plumose setae; articles I-III of palp in length radio 1.0: 2.3: 3.0, second article of palp with 11 marginal setae, article III with three A-setae, three B-setae, 19 D-setae, and five E-setae apically; incisor of right mandible with four teeth; lacinia mobilis bifurcate, with a row of small teeth at the end.

Lower lip (Fig. 5G ): inner lobes lacking, outer lobes covered with thin setae.

Maxilla I (Fig. 5J, K ): asymmetrical, left inner plate with 14 plumose setae on medial margin; outer plate with 11 robust serrated apical spines, each spine with small teeth; second article of left palp with six slender spines, two long setae and one spine with small setae; second article of right palp with five stout spines, one stiff seta and one slender spine.

Maxilla II (Fig. 4L ): inner plate with 15 plumose facial setae in an oblique row; inner and outer plates with long setae apically.

Maxilliped (Fig. 4M ): inner plate with three stout apical spines, one subapical spine, eight simple setae, and 12 plumose setae; outer plate bearing a row of blade spines and six plumose setae apically; article IV of palp hooked, with a group of setae at hinge of unguis.

Pereon. Gnathopod I (Fig. 6A, B ): coxal plate bearing one seta on both anterior and posterior margins; basis with long setae on anterior and posterior margins; carpus 1.1 times as long as wide, 0.7 times as long as propodus; propodus oval, palm with one medial spine and 16 spines on posterior margin and surface; dactylus with one seta on outer margin.

Gnathopod II (Fig. 6C, D ): coxal plate bearing three setae and one seta on anterior and posterior margins; basis with long setae on anterior and posterior margins; carpus 1.2 times as long as wide, 0.6 times as long as propodus; propodus subrectangular, palm margin with one medial spine and four spines on lateral posterior margin and surface; dactylus with one seta on outer margin.

Pereopod III (Fig. 7A, B ): both anterior and posterior margins of coxal plate bearing one setae; basis elongate, with setae along anterior and posterior margins; merus with two spines accompanied by one seta on anterior margin and clusters of long setae on posterior margin, 1 spine accompanied by setae in anterodistal corner; carpus with five spines accompanied by setae on posterior margin, one spine with setae in anterodistal corner; propodus with five spines accompanied by setae on posterior margin and one spine on posterodistal corner; dactylus with one plumose seta on anterior margin, and one setae at hinge of unguis.

Pereopod IV (Fig. 7C, D ): coxal plate concave, bearing five setae on posterior margin; basis with clusters of setae on anterior and posterior margin; merus has several clusters of setae on posterior margin and 1 spine on anterior margin, anterodistal corner with one spine accompanied by setae; carpus with five spines on posterior margin and two spines accompanied by setae on posterodistal corner; propodus with seven spines accompanied by setae on posterior margin and two spines on posterodistal corner; dactylus with one plumose seta on anterior margin and one seta at hinge of unguis.

Pereopod V (Fig. 7E, F ): coxal plate bearing two setae on posterior margin; basis expanded, with setae and six spines on anterior margin, anterodistal corner with one spine and three setae, posterior margin with seven setae; merus with three spines accompanied by setae on both anterior margin and anterodistal corner, posterior margin with one spine and posterodistal corner with three spines; carpus with three or two groups of spines on anterior margin and posterior margin, respectively; propodus with five groups of spines on anterior margin; dactylus with one plumose seta on posterior margin, and one seta at hinge of unguis.

Pereopod VI (Fig. 7G, H ): coxal plate bearing two setae on posterior margin; basis expanded, with three setae and four spines on anterior margin, anterodistal corner with two spines accompanied by setae, posterior margin with nine setae; merus with three pairs of spines on anterior margin and three spines accompanied by setae on anterodistal corner, posterior margin with one pair of spines and posterodistal corner with three spines; carpus with three or two groups of spines on anterior margin and posterior margin, respectively; propodus with five groups of spines on anterior margin, posterior margin with one spine and five setae; dactylus with one plumose seta on posterior margin, and one seta at hinge of unguis.

Pereopod VII (Fig. 7I, J ): coxal plate bearing three setae on posterior margin; basis expanded, with two setae and six spines on anterior margin, anterodistal corner with three spines, eleven setae on posterior margin and one spines accompanied by three setae on posterodistal corner, respectively; both mersus and carpus with three spines on anterior margin and one spine on posterior margin; propodus with five groups of spines on anterior margin and two setae on posterior margin; dactylus with one plumose seta on posterior margin and one seta at hinge of unguis.

Coxal gills (Figs 6C , 7A-E ): coxal gill of gnathopod II longer than basis; gills of pereopod III-V are almost as long as their basis; gills of pereopod VI-VII are shorter than their basis.

Pleon. Epimeral plates (Fig. 6E-G ): plate I ventrally rounded, bearing seven setae on anteroventral margin and two setae on posterior margin; plate II with four spines on ventral margin and four setae on posterior margin, posterodistal corner blunt; plate III with four spines on ventral margin and three setae on posterior margin, posterodistal corner subacute.

Pleopods (Fig. 7A-C ): similar, peduncle with two retinacula accompanied by two or three setae; outer ramus slightly shorter than inner ramus, both inner and outer rami fringed with plumose setae.

Urosome. Urosomites (Fig. 6H ): urosomite I with two-one-one-two spines accompanied by setae on dorsal margin; urosomite II with two-one-one-two spines accompanied by setae on dorsal margin; urosomite III with one-one-one-one spine accompanied by one seta.

Uropods I-III (Fig. 8D-F ): uropod I peduncle with one basofacial spine, one and three spines on inner and outer margins, with one and two spines on inner and outer distal corners, respectively; inner ramus with one spine on inner margin; outer ramus with one and two spines on inner and outer margins, respectively; both rami with five terminal spines. Uropod II peduncle with two spines on both inner and outer margins and one distal spine on each corner; inner ramus with three spines on inner margin, outer ramus with two spines on outer margin, both rami with five terminal spines. Uropod III peduncle with one spine accompanied by three setae and eight distal spines; inner ramus about 2.4 times as long as peduncle, reaching 0.7 times the length of outer ramus, with two spines on inner margin, both inner margin and outer margin have plumose setae; proximal article of outer ramus with five pairs of spines accompanied by several simple setae on outer margin, inner margin with both simple setae and plumose setae, and four distal spines accompanied by long simple setae; terminal article with long simple setae.

Telson (Fig. 7K ): deeply cleft, approximately as long as wide; left lobe with two spines and two setae on surface; right lobe with one spine and one single seta; each lobe bearing three distal spines.

Description of paratype female.

(GAHBH-002). 12.3 mm

Pereon. Gnathopod I (Fig. 9A, B ): coxal plate bearing one seta on both anterior and posterior margins; basis with long setae on anterior and posterior margins; propodus oval, palm with 8 spines on posterior margin and surface; dactylus with one seta on outer margin.

Gnathopod II (Fig. 9C, D ): coxal plate bearing three setae and one seta on anterior and posterior margins; basis with long setae on anterior and posterior margins; propodus subrectangular, palm margin with four spines on lateral posterior margin and surface; dactylus with one seta on outer margin.

Pereopods III-VII (Fig. 10A-E, J-N ): similar to those of males.

Oostegite (Fig. 9F-I ): oostegite of gnathopod II broad, oostegites of pereopods III-V elongated and oostegite of pereopod V smallest.

Urosome. Uropods I-III (Fig. 9G-F ): uropod I peduncle with one or three spines on inner and outer margins respectively, with one spine on both inner and outer distal corners; both rami with two spines on inner margin and five terminal spines. Uropod II peduncle with one or two spines on inner and outer margins respectively and one distal spine on each corner; both rami with two spines on inner margin and five terminal spines. Uropod III peduncle with one spine accompanied by setae and eight distal spines; inner ramus about 2 times as long as peduncle, reaching 0.8 times the length of outer ramus, with four spines on inner margin and one distal spine accompanied by long setae, both inner and outer margins have plumose setae; proximal article of outer ramus with one spine and three pairs of spines accompanied by several simple setae on outer margin, inner margin with both simple setae and plumose setae, and four distal spines accompanied by long simple setae; terminal article with long simple setae.

Telson (Fig. 8G ): deeply cleft, approximately as long as wide; left lobe with two spines and two setae on surface; right lobe with two setae; each lobe bearing three distal spines.

Habitat.

This species was collected from streams and the adjacent small puddles, usually under big rocks.

Remarks.

The new species Gammarus zhouqiongi sp. nov. is similar to G. takesensis in pereopods III and IV with straight setae on posterior margin; epimeral plates III with subacute posterodistal corners; and inner ramus of uropod III about 0.7 times as long as outer ramus. It differs from G. takesensis ( G. takesensis in parentheses) by accessory flagellum of antenna I with five articles (four articles); inner and outer margins of inner ramus and the inner margins of outer ramus of uropod III with long plumose setae (short plumose setae); posterodistal corner of basis of pereopod VII with spines and setae (only with setae).

Gammarus zhouqiongi sp. nov. is also similar to G. tastiensis in peduncle articles IV-V of antenna II with short setae; pereopods III and IV with long and straight setae on posterior margin; both inner and outer margins of inner ramus and the inner margins of outer ramus of uropod III with plumose setae, and outer margin of outer ramus of uropod III with simple setae. It can be distinguished from G. tastiensis by the following characters ( G. tastiensis in parentheses): inner ramus of uropod III more than 2 times as long as peduncle (inner ramus uropod III less than 2 times as long as peduncle); pereopods III-V are slender (strong).

A comparison between Gammarus species in Xinjiang is presented in the following key.

Figures

Figure 4. Gammarus zhouqiongi sp. nov., holotype.

Figure 5. Gammarus zhouqiongi sp. nov., male holotype A head B antenna I C flagellar article of antenna I with aesthetasc D antenna II E calceoli of antenna II F upper lip G lower lip H left mandible I incisor and lacinia mobilis of right mandible J left maxilla I K distal part of palp article II of right maxilla I L maxilla II M maxilliped.

Figure 6. Gammarus zhouqiongi sp. nov., male holotype A gnathopod I B propodus and dactylus of gnathopod I C gnathopod II D propodus and dactylus of gnathopod II E epimeral plate I F epimeral plate II G epimeral plate III H dorsal margins of urosomites I-III.

Figure 7. Gammarus zhouqiongi sp. nov., male holotype A pereopod III B dactylus of pereopod III C pereopod IV D dactylus of pereopod IV E pereopod V F dactylus of pereopod V G pereopod VI H dactylus of pereopod VI I pereopod VII J dactylus of pereopod VII K telson.

Figure 8. Gammarus zhouqiongi sp. nov. A-F male holotype G female paratype A plepod I B pleopod II C pleopod III D uropod I E uropod II F uropod III G telson.

Figure 9. Gammarus zhouqiongi sp. nov., female paratype (GAHBH- 002) A gnathopod I B propodus of gnathopod I C gnathopod II D propodus of gnathopod II E uropod I F uropod II G uropod III.

Figure 10. Gammarus zhouqiongi sp. nov., female paratype (GAHBH- 002) A pereopod III B pereopod IV C pereopod V D pereopod VI E pereopod VII F oostegite of gnathopod II G oostegite of pereopod III H oostegite of pereopod IV I oostegite of pereopod V J dactylus of pereopod III K dactylus of pereopod IV L dactylus of pereopod V M dactylus of pereopod VI N dactylus of pereopod VII.