Caridina zhujiangensis, Chen & Chen & Guo, 2018

Chen, Qing-Hua, Chen, Wen-Jian & Guo, Zhao-Liang, 2018, Caridean prawn (Crustacea, Decapoda) from Dong'ao Island, Guangdong, China, Zootaxa 4399 (3), pp. 315-328 : 319-323

Caridina zhujiangensis , new species

( Figs. 4–6 )

Material. Holotype, adult female (FU, 14–08–23–01), tl 30.5 mm, cl 8.7 mm, rl 1.2 mm, near the Resort Hotel , Dong'ao Island, Guangdong Province (E 113°42'03", N 22°01'06", al. 19 m, stn.4), 23 August 2014, coll. Z. L. Guo. Paratypes: 4 males (FU, 14–08–23–02 to 05) , 11 females (FU, 14–08–23–06 to 15), same data as holotype .

Diagnosis. Rostrum short, extending to end of first segment of antennular peduncle, unarmed dorsal but ventral margin bearing 1 teeth. Endopod of the first male pleopod is sub-rectangular, slightly wider proximally, distal margin broadly rounded, inner margin slightly concave, outer margin slightly convex; appendix interna well developed, arising from distal 1/3 of endopod, just reaching beyond tip of endopod. Appendix masculina rodshaped, reaching about 0.67 times length of endopod, inner margin and distally bearing numerous stout spines; appendix interna reaching about half length of appendix masculina.

Description. Body: slender and sub-cylindrical, males up to 23.5 mm tl, females up to 30.5 mm tl.

Rostrum. ( Fig. 4a ) Short and narrow, only 0.15–0.19 of cl, usually reaching end of eye to the end of first antennular segment; curving downwards; dorsal border without tooth; ventral border with 0-5 tooth (usually 0); lateral carina dividing rostrum into two unequal parts, continuing posteriorly to orbital margin.

Eyes. ( Fig. 4a ) Small, on short ocular peduncle, cornea globular, well developed.

Carapace. ( Fig. 4a ) Smooth, glabrous; lower orbital angle indistinct; pterygostomian margin rounded, slightly produced forward; pterygostomian spine absent. Antennal spine pointed sharply and placed below orbital angle, long and strong.

Antennule. ( Fig. 4a, b ) Peduncle reaching beyond scaphocerite; stylocerite about 0.70–0.72 times as long as proximal segment; second segment about 0.48–0.56 times as long as proximal segment, about 1.0–1.2 time as long as distal segment; all segments with sub-marginal plumose setae.

Antenna. ( Fig. 4a, c ) Peduncle about 0.51–0.64 times as long as scaphocerite; scaphocerite length about 2.9– 3.6 times width, outer margin straight, asetose, ending in a strong sub-apical spine, inner and anterior margins with long plumose setae.

Mandible. ( Fig. 4d ) Without palp; left incisor process with 3 sharp teeth; medially 2 groups of setae; molar process ridged.

Maxillula. ( Fig. 4e ) Lower lacinia broadly rounded; upper lacinia broadly elongate, medial edge stright, with several rows of strong spinules; palp simple, slightly expanded distally, with 2 long simple setae, upper, middle and lower endite with simple marginal and sub-marginal setae.

Maxilla. ( Fig. 4g ) Scaphognathite tapers posteriorly, distally with regular row of long plumose setae and short marginal plumose setae continuing down proximal triangular process, furnished with numerous long plumose setae, the latter with prominent basal dilation; upper and middle endite with marginal simple, denticulate and submarginal simple setae, distally with plumose setae; lower endite with long simple marginal setae; palp shorter than the cleft of upper endite, wider proximally than distally.

First maxilliped. ( Fig. 4f ) Palp broadly triangular ending in fringe-like tip and with terminal plumose setae; caridean lobe broad; exopodal flagellum well developoed; ultimate and penultimate segments of endopod indistinctly divided; medial and distal margins of ultimate segment with marginal and sub-marginal rows of simple, denticulate and plumose setae; penultimate segments with marginal long plumose setae.

Second maxilliped. ( Fig. 4h ) Ultimate and penultimate segments of endopod indistinctly divided; inner margin of ultimate, penultimate and basal segments with long plumose setae; exopod long.

Third maxilliped. ( Fig. 4i ) Reaches to end of second antennular peduncle segment, endopod three-segmented, length of penultimate segment about 0.87–0.92 times as long a basal segment; distal segment about 0.88–0.95 times as long as penultimate segment, ending in a large claw-like spine surrounded by simple setae, preceded by about 5–8 spines on distal third of posterior margin, proximally a clump of long and short simple, serrate setae; exopod reaches to about 0.45 times of second segment of endopod, distal margin with long plumose setae.

Branchial formula typical for genus.

First pereiopod. ( Fig. 4j ) Reaches end of eyes; chela 2.0–2.2 times as long as wide, about1.3–1.8 times length of carpus; movable finger 2.2–2.8 times as long as wide, 0.54–1.09 times length of palm; carpus excavated distodorsally, 1.2–1.5 times as long as wide, about 0.83–0.92 times length of merus.

Second pereiopod. ( Fig. 4k ) Reaches about end of second antennular peduncle segment, more slender and longer than first pereiopod; chela about 1.9–2.5 times as long as wide; about 0.70–0.92 times length of carpus, movable finger 3.9–4.1 times as long as wide and 1.2–1.4 times length of palm; setal brushes well developed; carpus 4.1–4.7 times as long as wide, slightly excavated distally, about same length of merus.

Third pereiopod. ( Fig. 5a, b ) 1/4 distal propodus reaches beyond end of scaphocerite; dactylus 2.8–3.7 times as long as wide, ending in prominent claw-like spine surrounded by simple setae, behind which bears 4–6 spines; propodus 3.4–4.2 times length of dactylus, bearing numerous thin spines on posterior margin plus a few of thin spines on the anterior and lateral margin, about 7.1–8.9 times as long as wide; carpus about 0.67–0.82 times length of propodus; merus 1.7–1.9 times as long as carpus, longer and broader than propodus, with about 2–3 strong spines on the posterior lateral margin.

Fourth pereiopod. Reaches middle of second segment of antennular peduncle, proportion and spination similar to third pereiopod.

Fifth pereiopod. ( Fig. 5c, d ) Reaches end of second segment of antennular peduncle; dactylus 2.3–3.9 times as long as wide, ending in claw-like spine surrounded by simple setae, behind which bears comb-like row of 45–48 spines on posterior margin; propodus 3.9–4.1 times length of dactylus, bears numerous thin spines on posterior margin, about 8.9–10.9 times as long as wide; carpus 0.58–0.85 times as long as propodus; merus 1.4–1.6 times as long as carpus, with 2–3 strong spines on posterior margin.

First pleopod. ( Fig. 5e ) Endopod in male is rectangular, wider proximally, about 0.45 times length of exopod, 2.5 times proximal width, tip broadly rounded, inner margin bearing nearly equal spines, outer margin and tip bearing numerous nearly equal long plumose setae, basal part of outer margin with marginal simple setae; appendix interna well developed, arising from distal 1/3 of endopod, slightly longer than width of endopod, reaching beyond end of endopod, distally with numerous cincinuli.

Second pleopod. ( Fig. 5f ) Appendix masculina rod-shaped, reaching about 0.66 times length of endopod, inner margin and tip bearing two rows of stout spines; appendix interna reaching about 0.63 times length of appendix masculina, longer than width of appendix masculina, distally with many cincinuli.

Telson. ( Fig. 5g ) 0.66–0.81 times cl, distinctly longer than sixth abdominal segment, tapering posterior, ending in rounded margin, dorsal surface with 5–6 pairs of stout movable spines including the pair at poster lateral angles; posterior margin with 4 pairs of nearly equal long intermedial plumose setae. Exopodite of the uropod bears a series of 18–20 stout spines along the diaeresis ( Fig. 5h ).

Eggs size. 0.22–0.27 x 0.35–0.39 mm in diameter.

Colouration. When alive, body is green-brown colour and translucent, the dorsal carapace is darker than the lateral carapace, and the body are dispersed with orange spots ( Fig. 6 ).

Habitat. The type specimens were collected from a small pool, near the Resort Hotel, Dong’ao Island, Guangdong Province (E 113°42'03", N 22°01'06", al. 19 m). The pool with rocky bed, is about 1 m ² and about 0.1 m in depth, and the water is clear and flowing, the shrimps live under the stones.

Etymology. As Pearl river is also called “Zhujiang”, the longest river within Guangdong province’s boundary, and the Dong’ao island is locates the mouth of Pearl river. The new species is named after its distributional area, the Zhujiang.

Remarks. Caridina zhujiangnensis is most similar to C. typus Milne-Edwards, 1837 in the shape of appendix masculina of male second pleopod and same egg size. It can be distinguished from C. typus by shorter rostrum (reaching the end of eye versus reaching the end of second antennular segment); the longer appendix interna of endopod of male pleopod (arising from distal 1/3 of inner endopod and slightly longer than width of endopod versus arising form distally and distinct shorter than proximal width in C. typus); the broader carpus of second pereiopod (carpus 4.09–4.64 times of width verus 5.4 times); the dactylus of fifth pereiopod bears less spines (bears comb-like row of 45–48 spines versus 100); the shorter appendix interna of male second pleopod (reaching about to half length of appendix masculina versus reaching about to 0.9 times).

Distribution. Guangdon Province, southern China.

Figures

FIGURE 4. Caridina zhujiangensis, new species. a. cephalothorax, holotype, female (FU, 14–08–23–01), tl 30.5 mm, cl 8.7 mm; b. antennular; c. antenna; d. mandible; e. maxillula; f. first maxilliped; g. maxilla; h. second maxilliped; i. third maxilliped;j. first pereiopod, k.second pereiopod.b-n: paratype, male, cl 5.8 mm (FU, 14–08–23–02).

FIGURE 5. Caridina zhujiangensis, new species. a. third pereiopod; b. dactylus of the third pereiopod; c. fifth pereiopod; d. dactylus of the fifth pereiopod, e. first pleopod of the male; f. second pleopod of the male; g. posterior portion; h. diaeresis of the telson.b-n:paratype, male, cl 5.8 mm (FU, 14–08–23–02).

FIGURE 6. Caridina zhujiangensis, new species, live specmen, showing the characteristic colouration, male, cl. 8.5 mm.