Anonyx gurjanovai Steele, 1986

Kim, Jun-Haeng Heo and Young-Hyo, 2021, Two new record of the genus Anonyx (Crustacea: Amphipoda: Uristidae) from Korean waters, Journal of Species Research 10 (3), pp. 267-275 : 267-270

Anonyx gurjanovai Steele, 1986 ( Figs. 1-3 )

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Anonyx affinis Gurjanova, 1951 ; 224, pl. 89; 1962: 234, pl. 74.

Anonyx gurjanovai Steele, 1986: 2608 , figs. 10-12.

Material examined. 1♂ ( MABIK CR00248291 ), Gajin Port , Gajin-ri , Goseong-gun, Gangwon-do, Korea, 38° 22 ʹ 05 ʺ N, 128°30 ʹ 45 ʺ E, 22 February 2005, Y.H. Kim ; 1♂, Geojin Port , Geojin-ri , Goseong-gun, Gangwon-do, Korea, 38°26 ʹ 38 ʺ N, 128°27 ʹ 57 ʺ E, 24 February 2005, Y.H. Kim ; 1♂, Geojin Port , Geojin-ri , Goseong-gun, Gangwon-do, Korea, 38°26 ʹ 38 ʺ N, 128°27 ʹ 57 ʺ E, 11 March 2006, Y.H. Kim ; 6♂, Bongpo Port , Bongpo-ri , Goseong-gun, Gangwon-do, Korea, 38°15 ʹ 07 ʺ N, 128°34 ʹ 02 ʺ E, 23 February 2007, Y.H. Kim ; 1♂, 28 December 2019, J.H. Heo. The specimens were collected using a light trap.

Description. Adult male, body ( Figs. 1 , 2A ) 8.50 mm long (MABIK CR00248291), dorsally smooth. Head lateral cephalic lobe subacute; eye medium, reniform, black. Epimeron 3 round with small projection posteroventrally. Urosomite 1 with dorsal depression and dorsal mid-carina.

Antenna 1 ( Fig. 2B ), peduncular article 1 stout, with 2 penicillate setae dorsally; peduncular articles 2-3 strongly telescoping, short; length ratio of peduncular articles 1-3 = 1.00: 0.25: 0.18; flagellum 15-articulate, 1.32 times longer than peduncular articles, with callynophore, article 2, 4, 6 with calceoli ventrally; accessory flagellum 9-ar- ticulate, article 1 elongated.

Antenna 2 ( Fig. 2C ) slender, elongated; peduncular article 4 subrectangular, 1.36 times as long as article 5, with a row of setules dorsally, ventral margin expanded, with 3 penicillate and 4 long simple setae; flagellum 22-articu- late, calceoli on flagellum articles.

Left mandible ( Fig. 2D ), incisor broad and smooth with bifid tooth on the cutting edge, lacinia mobilis simple, cy- lindrical (finger-like); accessory spine row with 3 spines and 1 setaceous spine; molar process well developed, columnar, distally truncate and triturative, densely pubescent; palp attached nearly midway, 3-articulate; article 1 short; article 2 longest, with 4 A2-setae; article 3 weakly falcate, 0.85 times as long as article 2, with 15 D3-setae, 3 E3-setae and covered with setules laterally.

Right mandible ( Fig. 2E ) similar to left one, except for the 1 prominent tooth on the cutting edge.

Gnathopod 1 ( Fig. 2F ) subchelate; coxa large, expanded anteriorly, 0.69 times as wide as long; basis with unequal simple setae on both margins; merus subequal in length to ischium, with setules posteriorly and 4 simple setae posterodistally; carpus produced posterodistally, with setules, two clusters of simple setae distally, 0.51 times as long as basis; propodus subrectangular, 1.18 times as long as carpus, palm concave, defined by 2 stout spines posterodistally; dactylus falcate, slightly exceeding palm.

Gnathopod 2 ( Fig. 2G ), coxa subrectangular, 0.49 times as wide as long; basis linear, elongated, with simple setae on both margins; ischium elongated, 1.44 times as long as merus, with 3 simple setae anteriorly and 4 unequal simple setae posterodistally; merus 0.57 times as long as carpus, with patch of setules posteriorly and a cluster of long setae posterodistally; carpus 0.55 times as long as basis, covered with setules laterally, posterodistal margin with spinules and long setae, clusters of long setae distally; propodus short, subquadrate, minutely chelate, with unipinnate setae anterodistally, covered with spinules posterodistally, 0.57 times as long as carpus; dactylus small, acute, fitting palm.

Pereopod 3 ( Fig. 2H ), coxa subrectangular, width 0.48 times length; basis narrowing proximally; merus produced anterodistally, subequal in length to propodus, with unequal simple setae posteriorly and 3 unequal simple setae anterodistally; propodus subrectangular, 1.56 times as long as carpus, with a row of paired long simple setae with spines and 1 blunt spine hooked; dactylus falcate, 0.50 times as long as propodus.

Pereopod 4 ( Fig. 2I ) similar to pereopod 3 except coxa broader than that of pereopod 3, posterior margin excavate, posterodistal lobe produced.

Pereopod 5 ( Fig. 3A ), coxa large, rounded quadrate, equilobate, width 1.19 times length; basis subquadrate, width 0.85 times length, posterior margin serrate, posteroventral lobe rounded and expanded, with a row of spines along anterior margin; merus expanded posteriorly, anteri- or margin with 4 spines and 3 long setae, posterior margin with 3 robust spines; carpus subequal in length to merus, with 4 spines and 1 long seta; propodus slender, rectangular, slightly longer than carpus, anterior margin with a row of robust spines; dactylus falcate, 0.50 times as long as propodus, with 1 penicillate seta posteriorly.

Pereopod 6 ( Fig. 3B ) similar to pereopod 5, but coxa small, bilobate, anterior lobe small; each article longer in proportion than pereopod 5.

Pereopod 7 ( Fig. 3C ), coxa small, subquadrate; basis subovate, posterior margin serrate, round and convex, width 0.82 times length, anterior margin nearly straight, with a row of spines; ischium to dactylus similar to those of pereopod 6, except ischium and merus without simple setae anteriorly.

Uropod 1 ( Fig. 3D ), peduncle subrectangular, 1.20 times as long as outer ramus, with a row of 6 dorsolateral robust spines and 5 long dorsomedial robust spines; outer ramus 1.06 times as long as inner one, lateral margin with 3 robust spines, inner ramus with 2 robust spines on each margin.

Uropod 2 ( Fig. 3E ), peduncle subquadrate, subequal in length to outer ramus, with a row of 3 dorsal robust spines; outer ramus subequal in length to inner one, with 2 lateral spines, inner ramus with 2 medial and 1 lateral spines.

Uropod 3 ( Fig. 3F ), peduncle short, 0.54 times as long as outer ramus, with 1 dorsomedial, 3 dorsolateral, and 3 ventrodistal spines; outer ramus 1.09 times as long as inner ramus, biarticulate, proximal article with 8 plumose setae along medial margin, lateral margin with 4 spines, each margins with 1 distal robust spine, distal article short, 0.13 times as long as proximal one; inner ramus not reaching end of proximal article of outer ramus, medial margin with 10 plumose setae and 3 spines, lateral margin with 2 robust spines and 1 plumose seta.

Telson ( Fig. 3G ) much longer than broad, cleft about 77 % of its length, each lobe with deep apical notch bearing 1 stout spine and 1 penicillate seta, 2 robust spines and a pair of penicillate setae dorsolaterally.

Distribution. Southern British Columbia to Japan, Korea (East Sea).

Remarks. Anonyx gurjanovai Steele, 1986 belongs to the A. laticoxae group comprising A. laticoxae Gurjanova, 1962 ; A. schefferi Steele, 1986 ; A. stegnegeri Steele, 1986 ; A. hurleyi Steele, 1986 ; A. multiarticulatus (Pearse, 1913) ; A. petersoni Steele, 1986 ; A. affinis Ohlin, 1895 ; A. sculptifer Gurjanova, 1962 ; A. magnus Gurjanova, 1962 ; A. orientalis Gurjanova, 1962 ; A. volkovi Kudrjaschov, 1965 ; and A. exilipes Jung, Coleman, Kim and Yoon, 2018 , which posesses an unconstricted inner ramus of uropod 2 and is prevalent in the North Pacific. This species is the smallest known species of the genus Anonyx ( Steele, 1986) . Anonyx gurjanovai is similar to A. stegnegeri , but can be distinguished through the outer ramus of uropod 3 based on the presence of an elongated distal article and a straight projection on the epimeron 3 (vs. significantly shorter distal article and an upturned projection in A. stegnegeri ). Anonyx gurjanovai is also similar to A. hurleyi , but differs based on the lack of lateral setae on the inner ramus of uropod 3 ( Steele, 1986). Our specimen represents an adult male, and exhibits characteristics similar to that of male gnathopod 1 with a concave palm ( Steele, 1986).

Figures

Fig. 1. Anonyx gurjanovai Steele, 1986, adult male, 8.50 mm, habitus. Scale bar=1.0 mm.

Fig. 2. Anonyx gurjanovai Steele, 1986, adult male, 8.50 mm.A, habitus; B, antenna 1; C, antenna 2; D, left mandible; E, right mandible; F, gnathopod 1; G, gnathopod 2; H, pereopod 3; I, pereopod 4. Scale bars: A=1.0 mm, B-G=0.2 mm, H, I=0.5 mm.

Fig. 3. Anonyx gurjanovai Steele, 1986, adult male, 8.50 mm. A, pereopod 5; B, pereopod 6; C, pereopod 7; D, uropod 1; E, uropod 2; F, uropod 3; G, telson. Scale bars:A-C, G =0.5 mm, D-F=0.2 mm.