Sinocorophium dongtanense, Ren, Xianqiu & Liu, Wenliang, 2014

Ren, Xianqiu & Liu, Wenliang, 2014, A new species of Sinocorophium from the Yangtze estuary (Crustacea: Amphipoda: Corophiidae: Corophiinae: Corophiini), China, Zootaxa 3887 (1), pp. 95-100 : 96-100

Sinocorophium dongtanense sp. nov.

( Figs 1–3 )

Material examined. Holotype: ♂ (11.8 mm), 2005-CA-007, Dongtan wetland, Chongming island, Yangtze estuary, 31.71008°N 121.55046°E, intertidal zone, soft mud, coll. Wenliang Liu, 10 April 2005. Paratype: ♀ (12.0 mm), 2005-CA-008, Dongtan wetland, Chongming island, Yangtze estuary, 31.71008°N 121.55046°E, intertidal zone, soft mud, coll. Wenliang Liu, 10 April 2005; 8 ♀♀ (3.5–7.0 mm), 3 ♂♂ (4.0–6.0 mm), 20080528-1, Dongtan wetland, Chongming island, Yangtze estuary, 31.58587°N 121.90219°E, intertidal zone, soft mud, coll. Wenliang Liu, 28 May 2008.

Non-type material. ovigerous ♀ (6.8 mm), ♂ (7.0 mm), 20100716-1, Chongxi wetland, Chongming island, Yangtze estuary, 31.72376°N 121.24242°E, intertidal zone, soft mud, coll. Wenliang Liu, 16 July 2010.

Description. Body slender, depressed ( Fig. 1 A). Head shorter than combine of pereonites 1 and 2 in length. Male rostrum not beyond lateral corners of head ( Fig. 1 C). Female rostrum longer, beyond lateral corners ( Fig. 1 D). Eyes small and round. Pereonites short and wide, smooth. Posterolateral angle of pleonites 1 and 2 round, with plumose setae. Pleonite 3 longer, lateroventral margin medial concave, with setae, posteroventral angle round ( Fig. 1 B). Urosome free ( Fig. 1 L). Telson wider than long, lateral angles projected, dorsomedial part concave, distal end slightly projected, lateral surface rough, semicircle shape ( Fig. 1 M).

Male antenna 1 ( Fig. 1 F, G) shorter than terminal margin of peduncular article 4 of antenna 2, peduncle longer than flagellum, length ratio of peduncular articles 1–3 about 10:5:3. Peduncular article 1 slender, inner dorsal margin serrated, with a row of small teeth, ventral margin slight concave, medial ridge serrated, with a row of small teeth and fine short hairs; peduncular article 2 shorter, basal half of ventral margin with 2 small protuberances and groups of setae; peduncular article 3 short. Flagellum 17- 18-articulated, each article with short setae. Male antenna 2 ( Fig. 1 H, I) massive, peduncle stout. Inner ventral side of peduncular article 2 with 2 stout teeth, inner tooth larger than outer; peduncular article 3 shorter, inner ventrodistal side with a small projection; peduncular article 4 long and stout, inner terminal lateral side with 2 stout teeth, outer lateral tooth larger than inner, inner lateral side with 2 rows of teeth, 6 small teeth and 3 larger teeth respectively; peduncular article 5 small and shorter than 4, inner ventral side of basal half with 2 stout teeth and dispersed setae. flagellum short, about 1/4 as long as peduncle, 2-articulated. Inner ventral side of flagellar article 1 with a row of 6 small teeth, distal tooth large, and group of setae. Flagellar article 2 short, distal end with setae.

Female antenna 1 ( Fig. 1 E) slender, beyond peduncular article 4 of antenna 2. Peduncle longer than flagellum. Length ratio of peduncular articles 1–3 about 5:3:2. Peduncle smooth, with setae, without teeth-row. Female antenna 2 ( Fig.1 J, K) slight slender and shorter than male’s. Peduncle longer than flagellum. Inner ventral side of peduncular article 2 with 2 stout teeth also, outer lateral tooth smaller; inner ventroterminal end of peduncular article 3 with a small spine; peduncular article 4 strong, inner ventral end with 2 stout teeth, inner ventrolateral surface with 4 small teeth and a distal spine, formed a row, inner medio-lateral surface with a large teeth; inner ventrolateral surface of basal half of peduncular article 5 with 2 strong teeth. Flagellum shorter than peduncle. Flagellar article 1 long and smooth, with setae; flagellar article 2 short and small, with distal setae.

Lateral angle of upper lip ( Fig. 2 G) round, medial part of anterior margin with 2 shallow notches, both side with short fine hairs. Mandible ( Fig. 2 H, I): incisor with 3–4 small teeth, lacinia moblis with 3 teeth; spine-row with 3–4 spines; molar developed, triturative form; palp 2 articles, subequal to length, distal end of each article with a plumose seta. Inner lobe of lower lip developed, ridge of outer lobe with short fine hairs, lateral angles round and projected. Inner plate of maxilla I small ( Fig. 2 J), outer plate with 7 spines, palp 2 articulated, article 1 short, article 2 slender, terminal end with a row of spines. Two plate of maxilla II ( Fig. 2 K) narrow and longer, frontal margin and terminal end with long setae. Maxilliped strong ( Fig. 2 M), inner plate with terminal setae, frontal margin of outer plate with long setae, palp 4-articulated, article 3 short, article 4 needle-form.

Coxa of gnathopod 1 narrow and long, projected forward, distal end with 3–4 setae; basis longer; length ratio of carpus and propodus about 5:4, propodus narrow and longer, ventral margin slight concave inward, palmar margin slightly arched, with small spines; dactylus claw-shaped. Gnathopod 2 normal form, coxa longer than deep; outer anterolateral side of basal part of basis with a small tooth, frontal margin smooth, without teeth; Ischium, merus, carpus and propodus normal, dactylus longer, about 2/3 as long as carpus, ventral margin with 3–4 setae.

Pereopods 3 and 4 normal form ( Fig. 2 A, B), coxa shallow and long, triangular; outer anterolateral side of basal part of basis with a small tooth also; dactylus about 6/7 as long as propodus. Pereopod 5 ( Fig. 2 C): anterior part of coxa wider than poster; basis stout, outer lateral side of basal part with a small tooth; anterior margin of merus with plumose setae; ventral surface of carpus with 2 rows of small teeth, terminal row with 8 stout spines, basal row with 3 small spines; ventroterminal margin with long plumose setae; propodus slender; dactylus clawshaped. Pereopod 6 similar to 5 ( Fig. 2 D), but long, ventral margin of basis with long and dense plumose setae; carpus with 2 rows of spines, 7 and 4 spines respectively. Pereopod 7 slender ( Fig. 2 E), coxa shallow and long, basis narrow and long, basal part wider, dorsal and ventral margins with long plumose setae; merus, carpus and propodus narrow and long; dactylus craw-shaped, shorter than 1/2 as long as propodus.

Coxal gills on pereopods 3–6, oval-form. Brood plates narrow and long from on gnathopod 2 to pereopod 5, 4 pairs, with long plumose setae.

Peduncle of pleopods broad and short ( Fig. 2 F), leaf-form, posteroventral corner with paired coupling hooks. Outer rami shorter than inner rami, both margins with long plumose setae.

Uropod 1 long and strong ( Fig. 1 L), peduncle longer than ramus, with a row of inner lateral strong robust setae and a row of outer lateral slender setae, outer terminal end with a row of setae of spine-form. Ramus short, outer rami longer than inner, basal outer lateral side with 3 spines, inner lateral margin with a row of spines; outer lateral margin of inner rami with a row of spines. Uropod 2 shorter, outer distolateral side of peduncle with a group of setae, inner distolateral end with a spine; both ramus subequal, two margins of outer rami with small spines; outer margin of inner rami with a row of spines. Uropod 3 short, peduncular distal part thicker than basal part, outer distal end with group of setae, inner distal end with a seta; uniramous, ramus long-oval slightly shorter than peduncular, terminal margin with setae.

Etymology. The species name is based on the typical locality, Dongtan wetland in the Yangtze estuary.

Remarks. In the genus Sinocorophium , the new species S. dongtanense and two other species S. hangangense Kim, 2012 known from brackish water regions of Korea, S. homoceratum ( Yu, 1938) known from Bohai sea differ from other species in the relatively large body size (more than 10 mm). S. dongtanense is similar to S. homoceratum ( Yu, 1938) by peduncular article 1 of male antenna 1 in which the inner dorsal margin and ventral margin are serrated and by antenna 2, peduncular article 4 which has two large ventrodistal teeth. It differs from the latter in the inner lateral side of peduncular article 4 of male antenna 2 which has two rows of teeth, the basal half of peduncular article 5 which has two strong teeth and first flagellar article which bears small teeth.

Distribution and habitat. Sinocorophium dongtanense is currently only known from the Yangtze estuary, inhabiting U-type tube of soft mud in intertidal zone ( Fig. 3). This species is a true estuarine component, and the range of salinities for its occurrence was 0–25‰.

Figures

FIGURE 1. Sinocorophium dongtanense sp. nov. A – C, F – I, L – O: holotype male; D – E, J – K: paratype female, 2005 - CA- 008. A. entire animal, lateral view; B. epimeron 1 – 3; C – D. head, antenna 1 and antenna 2; E – G. antenna 1; H – K. antenna 2, ventral and lateral view; L. urosome; M. telson, lateral view; N, O. gnathopod 1 – 2.

FIGURE 2. Sinocorophium dongtanense sp. nov. holotype male. A – E. Pereopods 3 – 7; F. pleopod 1; G. upper lip; H, I. mandible; J. maxilla I; K. maxilla II; L. lower lip; M. maxilliped.