Gammarus illustris, Hou & Li, 2010
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https://doi.org/ 10.1111/j.1096-3642.2009.00603.x |
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https://treatment.plazi.org/id/AD798550-F113-FFAE-FCC0-D343FB8ABDFD |
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Valdenar |
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Gammarus illustris |
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sp. nov. |
GAMMARUS ILLUSTRIS SP. NOV. ( FIGS 4–8 View Figure 4 View Figure 5 View Figure 6 View Figure 7 View Figure 8 )
Synonymy: Gammarus sp1 Hou et al., 2007: 599.
Material examined: Holotype (IZCAS-I-A171), male, Wuxu Lake (29°6′N, 101°24′E), altitude 3600 m, Jiulong County, Sichuan Province, collected by Z. Hou and Y. Lin, 26.vii.2004 GoogleMaps . Paratypes (from IZCAS-I- A171-2 to IZCAS-I-A171-26): 12 males, nine females, and four juveniles, same locality as holotype GoogleMaps .
Etymology: The specific name ‘illustris’ is derived from the name of the type locality, ‘Wuxu Lake’, meaning ‘shining lake’ in Tibetan.
Diagnosis: Calceoli absent on antenna 2; posterodistal corner of epimeral plates 1–3 with small acute tooth; urosomite 1 with setae only on dorsal margin and no spines; inner ramus of uropod 3 reaching 0.2 times the length of outer ramus, both inner and outer ramus densely set with simple setae.
Description
Holotype: male
Body length: 8.5 mm.
Head ( Fig. 4A View Figure 4 ): eyes oval, 1.6 times as long as wide; inferior antennal sinus distinct, ventral recessed margin nearly straight.
Antenna 1 ( Fig. 4B View Figure 4 ): peduncular articles 1–3 in length ratio 1: 0.8: 0.5, with lateral and distal setae; flagellum with 22 articles, aesthetascs present from articles 5–20; accessory flagellum with three articles; both primary and accessory flagella with distal setae.
Antenna 2 ( Fig. 4C View Figure 4 ): peduncular article 4 about as long as article 5, both with three to four groups of long setae along anterior and posterior margins; flagellum with 11 articles, calceoli absent.
Upper lip ( Fig. 4D View Figure 4 ): convex, with minute setae.
Left mandible ( Fig. 4E View Figure 4 ): incisor with five teeth; lacinia mobilis with four teeth; spine row with five pairs of setae; molar with one plumose seta; palp article 2 with 12 marginal setae, article 3 about 0.85 times as long as article 2, with three A-setae on outer surface, three B-setae on inner surface, a row of 16 D-setae on posterior margin, and four E-setae apically.
Right mandible ( Fig. 4F View Figure 4 ): incisor with four teeth, lacinia mobilis bifurcate, with small teeth.
Lower lip ( Fig. 4G View Figure 4 ): inner lobe absent.
Maxilla 1 ( Fig. 4H–J View Figure 4 ): asymmetrical, left inner plate with a row of 11 plumose setae; outer plate with 11 serrated apical spines, each spine with small teeth; second article of palp with five slender spines and three stiff setae on medial surface; right palp wider, article 2 with four stout spines, one pectinate spine, and one seta.
Maxilla 2 ( Fig. 4K View Figure 4 ): inner plate with a row of ten plumose setae and with medial setal row; outer plate with apical setae and setules on lateral margin.
Maxilliped ( Fig. 4L View Figure 4 ): inner plate with three stout apical and one subapical spines; outer plate with nine blade spines, six pectinate spines; palp article 4 hooked, with a group of setae at hinge of unguis.
Gnathopod 1 ( Fig. 5A, C View Figure 5 ): coxal plate subrectangular, with three setae on anterior corner; basis with long setae on anterior and posterior margins; carpus short, 1.5 times as long as wide, about 0.8 times as long as propodus; propodus oval, palm oblique, with one medial spine and nine spines on posterior margin; dactylus with one seta on outer margin and two short setae at hinge of unguis.
Gnathopod 2 ( Fig. 5B, D View Figure 5 ): coxal plate with three setae on anterior corner and one seta on posterior corner; basis with long setae along anteroproximal and posterior margins; carpus with parallel margins, 1.9 times as long as wide, about 0.7 times as long as propodus; propodus subrectangular, palm margin subacute, with one medial spine and two spines on medial posterodistal corner and two spines on lateral posterodistal corner; dactylus with one seta on outer margin and one seta near the hinge of unguis.
Pereopod 3 ( Fig. 6A, F View Figure 6 ): coxal plate with three setae on anterior corner and one seta on posterior corner; basis with long setae on posterior margin; merus and carpus densely set with long and weakly curled setae on posterior margin, merus with two spines accompanied by setae on anterior margin, carpus and propodus with spines on posterior margin; dactylus with one plumose seta on posterior margin, and two setae at hinge of unguis.
Pereopod 4 ( Fig. 6B, G View Figure 6 ): coxal plate with three setae on anterior corner, and four setae on posterior margin, posterior margin excavated; basis with groups of long setae on posterior margin; merus with three groups of straight setae on posterior margin, carpus and propodus with spines on posterior margin; dactylus with one plumose seta on posterior margin and two stiff setae at hinge of unguis.
Pereopods 5–7 slender.
Pereopod 5 ( Fig. 6C, H View Figure 6 ): coxal plate with one seta on anterior corner and four setae on posterodistal corner; basis posterior margin straight, posterior corner subquadrate, with two long setae and six spines on anterior margin, a row of 11 setae on posterior margin; merus with two groups of setae on anterior margin, and two spines on posterior margin; carpus with two groups of spines on anterior margin and two groups of spines on posterior margin; propodus with three groups of spines on anterior margin and two groups of setae or spine on posterior margin; dactylus with one seta on posterior margin and two setae at hinge of unguis.
Pereopod 6 ( Fig. 6D, I View Figure 6 ): coxal plate with three setae on posterodistal corner; basis elongate, with two groups of long setae and five spines on anterior margin, posterior margin subsigmoidal, with a row of ten setae; merus to propodus with groups of spines accompanied by short setae on anterior margin; dactylus with one plumose seta on posterior margin and two setae at hinge of unguis.
Pereopod 7 ( Fig. 6E, J View Figure 6 ): coxal plate with four setae on posterior margin; basis with long setae and a row of five spines on anterior margin, posterior margin expanded, shape convex, with 12 setae on posterior margin, inner surface with two setae; merus to propodus with two to four groups of spines accompanied by few short setae on anterior margin, propodus with two setae on posterior margin; dactylus with one plumose seta on posterior margin and two stiff setae at hinge of unguis.
Coxal gills: coxal gill of gnathopod 2 and gills of pereopods 3–5 a little shorter than bases; gill of pereopod 6 about half length of basis; gill of pereopod 7 smallest, less than half of basis.
Epimeral plates ( Fig. 5E–G View Figure 5 ): epimeron 1 ventrally rounded, with three long and two stiff setae on anterior corner, and two setae on posterior margin, posterodistal corner with small acute tooth; epimeron 2 with one long seta on anterior corner, one spine accompanied by one seta on ventral margin, posterodistal corner with small acute tooth, with four setae on posterior margin; epimeron 3 with one long seta and two spines on anterior corner, posterodistal corner with small acute tooth, with three setae on posterior margin.
Pleopods 1–3 subequal ( Fig. 5H–J View Figure 5 ), peduncle with long facial and marginal setae, with two retinacula accompanied by one to two setae on anterodistal corner; both inner and outer rami fringed with plumose setae.
Urosomites 1–3 dorsally flat ( Fig. 7A View Figure 7 ), urosomite 1 with four groups of long setae on dorsal margin, without spines; urosomite 2 with four spines accompanied by long setae on dorsal margin; urosomite 3 with one spine accompanied by long setae on each side and two setae on dorsal margin.
Uropod 1 ( Fig. 7B View Figure 7 ): peduncle with one basofacial spine, one spine on outer margin, two spines on inner margin, with one and two spines on inner and outer distal corners, respectively; outer ramus with one spine on outer margin and one spine on inner margin; inner ramus with one spine on inner margin, both rami with five distal spines.
Uropod 2 ( Fig. 7C View Figure 7 ): peduncle with one spine on inner and outer corners, respectively; outer ramus with one spine on outer margin; inner ramus with one spine on inner margin.
Uropod 3 ( Fig. 7D View Figure 7 ): peduncle with four short setae on lateral margin; inner ramus 0.6 times as long as peduncle, reaching 0.2 times the length of outer ramus, with one spine on lateral margin and one distal spine; article 1 of outer ramus with one single spine and two pairs of spines on outer margin, and two pairs of spines on distal margin, both margins densely set with simple setae, terminal article longer than adjacent spines.
Telson ( Fig. 7E View Figure 7 ): deeply cleft, 0.9 times as long as wide, each lobe with one distal spine accompanied by long setae and long setae on lateral surface.
Female: paratype (IZCAS-I-A171-2)
Body length: 8.1 mm.
Gnathopod 1 ( Fig. 8A, C View Figure 8 ): coxal plate with three setae on anterior corner and one seta on posterior margin; propodus oval, palm margin not as oblique as that of male, with six spines on posterodistal corner; dactylus with one seta on outer margin and three setae at hinge of unguis.
Gnathopod 2 ( Fig. 8B, D View Figure 8 ): propodus subrectangular, palm margin subacute, with three spines on posterodistal corner; dactylus with one seta on outer margin and two setae at hinge of unguis.
Pereopods 3 and 4 with straight setae on posterior margin ( Fig. 7F View Figure 7 ).
Uropod 3 ( Fig. 8E View Figure 8 ): inner ramus about 0.27 times as long as outer ramus, both rami with simple setae, terminal article of outer ramus longer than adjacent spines.
Telson ( Fig. 7K View Figure 7 ): cleft, 0.7 times as long as wide, each lobe with two distal spines accompanied by long setae, a pair of short and a pair of long setae on the surface.
Oostegites ( Fig. 7G–J View Figure 7 ): oostegite of gnathopod 2 broad, with marginal setae, oostegite of pereopods 3 and 4 elongate, oostegite of pereopod 5 smallest.
Habitat: The species occurs under detritus, where water flows through from peak of mountain.
Remarks: Gammarus illustris sp. nov. can be distinguished from G. curvativus by the following characters ( G. curvativus in parentheses): calceoli absent on antenna 2 (present); propodus of gnathopod 2 with long straight setae on dorsal margin (curled setae); urosomite 1 with setae on dorsal margin but no spines (with spines). This new species differs from G. gregoryi (state in parentheses) in calceoli absent (present); pereopod 3 with long setae on posterior margin (few setae on pereopod 3); urosomite 1 with four groups of setae (two groups of setae).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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