Sinocorophium homoceratum Yu, 1938

Kim, Young-Hyo, 2017, A new species and new record of the genus Sinocorophium (Crustacea, Amphipoda, Corophiidae) from Korean Waters, Zootaxa 4312 (1), pp. 155-164 : 160-161

Sinocorophium homoceratum Yu, 1938

( Figs. 5 , 6 )

Sinocorophium homoceratum Yu, 1938 , p. 85, figs. 1–6.

Material examined: 1 ♂, 9 ♂ (DKUAMP201704), Seokpo stream, Seokpo-ri , Jinseo-myeon, Buan-gun, Jeollabuk-do, Korea, 33° 35′ 36″N, 126° 34′ 58″E, 27 April 2015, collected with dredge on bottom, collected by KES.

Type locality. Tangku , Hopei, China.

Habitat. The new recorded species is found in brackish estuary with a water temperature of 21.5 degrees C, salinity of 6.1 PSU, and pH 8.2. Sediment is composed of gravels and sand.

Description. adult male, 5.4 mm, cat no. NIBRIV0000325973.

Body ( Figs. 5 A, 6A) about 5.4 mm long; head longer than pereonite 1; cephalic lobe produced; eye invisible in alcohol; length ratio of pereonites 1–7 = 1.00: 1.30: 1.30: 1.60: 2.00: 2.00: 1.40; coxae flat dorsoventrally, much shallower than pereonites, except coxa 1; urosomites 1–3 separated.

Antenna 1 ( Fig. 6 B) longer than head and pereonites 1–5 combined; peduncle 1.64 × longer than flagellum, peduncular article 1, ventral margin with several irregular tubercles and simple setae, length ratio of peduncular articles 1–3 = 1.00: 0.46: 0.32; flagellum 18-articulate, with small aesthetascs ventrodistally.

Antenna 2 ( Fig. 6 C) massive, peduncle stout; peduncular article 2 with 2 pointed unequal gland cones posterodistally; peduncular article 4 characteristic in form, long and stout, 1.14 × article 5, with 2 strong teeth ventrodistally; peduncular article 5 rectangular, with 2 tubercles anteromedially; length ratio of peduncular articles 2–5 = 1.00: 2.27: 6.07: 5.30; flagellum biarticulate, proximal one 0.59 × peduncular article 5, with 6 small spines on ventral margin, distal one short, about 0.19 × proximal one, surrounded by setae apically.

Urosomites 1–3 ( Fig. 6 D) separate; urosomite 1 longest, widest and slightly curved dorsally; uropods 1–3 arising laterally.

Uropod 1 ( Fig. 6 D) slightly extending beyond end of uropod 2; peduncle much longer than rami, 1.85 × outer ramus, lateral margin with short setae, medial margin with 4 robust setae; outer rami 1.3 × longer than inner.

Uropod 2 ( Fig. 6 D) peduncle slightly longer than rami, with apicodistal robust seta and cluster of setae laterally; rami subequal in length.

Uropod 3 ( Fig. 6 D) uniramous, peduncle short, subequal to ramus; ramus ovate, margins surrounded by simple setae.

Telson ( Fig. 6 D) fleshy, thickened, subtriangular, truncate distally, dorsolaterally with 2 simple setae.

Remarks. Among the species of genus Sinocorophium , only 2 other species have 2 ventrodistal teeth on peduncular article 4 of antenna 2: S. homoceratum and S. dongtanense Ren & Liu, 2014 . However, S. homoceratum is easily distinguished from S. dongtanense by smooth peduncular articles 4–5 of antenna 2, whereas S. dongtanense has distinct teeth on peduncular articles 4–5. Our specimens are well accorded with the original description given by Yu (1938).

Distribution. Korea (Buan-gun).

Figures

FIGURE 5. Sinocorophium homoceratum Yu, 1938, A, paratype, adult male, 8.4 mm, habitus, lateral; B, paratype, adult female, 8.6 mm, habitus, lateral. Scale bars = 2.0 mm (A, B).

FIGURE 6. Sinocorophium homoceratum Yu, 1938, paratype, adult male, 5.4 mm, cat no. NIBRIV 0000325973: A, habitus, lateral; B, antenna 1; C, antenna 2; D, urosomites, uropods, and telson. Scale bars = 0.5 mm (A – C), 0.4 mm (D).