Caridina longiacuta, Guo & Wang, 2005

Guo, Zhao-Liang & Wang, Xiao-Qing, 2005, Caridina longiacuta, a new species of freshwater atyid shrimp (Decapoda, Atyidae) from Hunan Province, China, Zootaxa 1008 (1), pp. 13-20 : 14-18

Caridina longiacuta , new species ( Fig. 1 )

Material examined: Holotype.Adult male( FSTC,92­08­01):tl 23.4mm,cl 5.6mm,rl 2.5mm . Paratypes. 6 males ( FSTC, 92­08­02 to 07): tl 17.2–21.4 mm, cl 4.0– 5.2 mm, rl 1.7–2.3 mm ; 14 females ( FSTC, 92­08­08 to 21), tl 20.1–26.1 mm, cl 4.5–5.8 mm, rl 1.9–2.5 mm, near Yuanliping village , Yizhang County, Hunan Province (ca. 25°25’N, 112°57’ E). 9 August 1992 .

Diagnosis: Rostrum long, extending to end of antennular peduncle, dorsal border bearing 12–18 teeth, with 5–7 teeth situated behind the posterior orbital margin, 1–4 ventral teeth. Endopod of the first male pleopod is leaf­shaped, inner margin with a few thin marginal spiniform setae; appendix interna well developed, arising from distal 1/4–1/3 of endopod, just reaching end or half­length beyond the end of endopod. Appendix masculina rod­shaped, reaching about 0.85 times length of endopod, inner margin and tip bearing numerous stout hamate setae; appendix interna reaching about half of appendix masculina. Eggs 0.67–0.72 x 0.97–1.05 mm in diameter.

Description: Small, slender and sub­cylindrical, males reach 23.4 mm tl, females reach 26.1 mm tl.

Rostrum ( Fig.1a ): Broad, 0.42–0.46 of cl, reaching tip of antennular peduncle, curving downwards; armed with 12–18 dorsal teeth, of which 5–7 situated on carapace behind the orbital margin, and 1–4 ventral teeth.

Eyes ( Fig.1a ): Small, on short ocular peduncle; cornea globular, well developed.

Carapace ( Fig.1a ): Smooth, glabrous. Lower orbital angle indistinct, almost fused to sharp antennal spine. Pterygostomian margin rounded, slightly produced forward; pterygostomian spine absent.

Antennule ( Fig.1b ): Peduncle three­segmented, not reaching beyond scaphocerite; stylocerite about 0.72–0.81 times as long as proximal segment; second segment about 0.54– 0.56 times as long as proximal segment, about 1.4 time as long as distal segment, anterolateral angle of basal antennular segment with long finger­like process, which is about 0.71–0.84 times of second segment. All segments with submarginal plumose setae.

Antenna ( Fig.1c ): Peduncle about 0.45 times as long as scaphocerite; scaphocerite slightly longer than antennular peduncle, outer margin straight, asetose, ending in a strong sub­apical spine; length about 3.3 times width, inner and anterior margins with long plumose setae.

Mandibles, maxillula, maxilla, first and second maxilliped, and branchial formula typical for genus.

Third maxilliped ( Fig.1d ): Reaches to tip of scaphocerite, endopod three­segmented, length of basal segment about 3.6 times width, slightly expanded distally; length of penultimate segment about 6.1 times width, about 1.1 times as long a basal segment; distal segment about 0.92 times as long as penultimate segment, ending in a large claw­like spine surrounded by simple setae, preceded by about 3–6 spines on distal fifth of posterior margin, proximally a clump of long and short simple, serrate setae; exopod reaches to about 1/ 4 of second segment of endopod, distal margin with long plumose setae.

First pereiopod ( Fig.1e ): Reaches tip of eyes; chela 1.9–2.0 times as long as wide, about 1.3–1.8 times length of carpus; movable finger 0.82–1.0 times length of palm; carpus excavated disto­dorsally, 1.2–1.5 times as long as wide, 0.57–0.75 times as long as chela and 0.72–0.84 times length of merus.

Second pereiopod ( Fig.1f ): More slender and longer than first pereiopod, reaches end of second antennular peduncle; chela about 1.9–2.5 times as long as wide, about 0.83–1.1 times length of carpus; movable finger 2.9–4.1 times as long as wide, 1.2–1.7 times length of palm; carpus 3.2–4.3 times as long as wide, slightly excavated distally, about 0.93–1.2 times as long as chela and about 0.73–0.95 times as long as merus.

Third pereiopod ( Fig. 1g, h ): The base of dactylus reaches beyond end of scaphocerite; dactylus 3.4–4.0 times as long as wide, ending in prominent claw­like spine surrounded by simple setae, behind which bears 3–5 spiniform setae; propodus about 3.2–3.9 times length of dactylus; carpus 0.61–0.72 times length of propodus; merus 1.9–2.4 times as long as carpus, with about 3–4 spiniform setae on postero­lateral margin.

Fourth pereiopod: Reaches tip of first segment of antennular peduncle, somewhat similar to third pereiopod.

Fifth pereiopod ( Fig.1i, j ): Reaches the end of second antennular peduncle segment; dactylus 3.5–4.3 times as long as wide, ending in claw­like spine surrounded by simple setae, behind which bears comb­like row of 34–48 spiniform setae on posterior margin; propodus about 3.2–4.0 times length of dactylus; carpus 0.46–0.59 times as long as propodus; merus 1.4–1.7 times as long as carpus, with about 3 spiniform setae on posterior margin; ischium with one spiniform setae on posterior margin.

First pleopod ( Fig.1k, m ): Endopod in male is leaf­shaped, about 0.48–0.58 times as long as exopod, wider proximally, tip broadly rounded, about 2.6–2.9 times as long as maximal width, inner border with a few thin marginal spiniform setae, 1/5 distally of outer margin and tip with long and strong spiniform setae, basal part of the outer border with marginal long plumose; appendix interna well developed, arising from 1/4–1/3 distal part, reaches tip or half of length overreaches the tip of endopod.

Second pleopod ( Fig.1n ): Endopod in male about 0.85 times as long exopod, bearing numerous long spiniform setae on the proximal portion; appendix interna reaching half of appendix masculina; appendix masculina rod­shaped, reaching to about 0.73 times length of endopod, bearing a row of long spines on inner margin and distally.

Abdomen: Glabrous, sixth abdominal somite 0.48–0.50 times cl.

Telson ( Fig.1o ): 0.54–0.58 times cl, distinctly longer than sixth abdominal segment, tapering posteriorly, ending in rounded margin, dorsal surface with 4–5 pairs of stout movable spines including the pair at posterolateral angles; posterior margin with 3–4 pairs of intermedial plumose setae and a small median point, lateral pair usually stouts and longest; diaresis on exopod bearing 10–12 spinules.

Live coloration: When alive, body is light green colour and with numerous small reddish dots.

Egg size: Small, eggs with size of 0.67–0.72 x 0.97–1.05 mm.

Etymology: The species name is derived from the Latin longia, long, and the Latin acuta, process, in reference to the anterolateral angle of basal antennular segment with long finger­like process.

Remarks: C aridina longiacuta , new species, most resembles C. angustipes Guo & Liang, 2003 in the shape of the endopod of the male first pleopod and appendix masculina of the male second pleopod. It can be distinguished from C. angustipes by the long rostrum (reaching beyond tip of antennular peduncle versus reaching tip of second antennular peduncle in C. angustipes ); anterolateral angle of basal antennular segment with long finger­like process (more 2/3 of second segment length versus less 1/3 of second segment length in C. angustipes ); the longer penultimate segment of third maxilliped (longer than the basal segment versus shorter than the basal segment in C. angustipes ); the narrower scaphocerite (3.3 times as long as wide versus 2.8 times in C. angustipes ); the posterior margin of telson with a small median point (versus without in C. angustipes ); and smaller eggs (eggs size 0.67–0.72 x 0.97–1.05 mm versus 1.06–1.20 x 1.58–1.71 mm in C. angustipes ).

Habitat: The senior author collected the type specimens from a small stream at an elevation of 450–700 m near Yuanliping village , Yizhang County, Hunan Province (ca. 25°25’ N, 112°57’ E). The stream has a rocky bed, is about 15–30 m wide and 0.5–2.0 m deep. The shrimps live under stones and aquatic grass beds. The temperature was 25 and pH was 7.0 .

Distribution: Only know from the type locality: Yizhang County, Hunan Province, China.

Figures

FIGURE 1. Caridina longiacuta sp. nov. a. cephalothorax, holotype, male, cl 5.6 mm (FSTC, 92­ 08­01), b. antennular peduncle, c. scaphognathite, d. third maxilliped, e. first pereiopod, f. second pereiopod, g. third pereiopod, h. dactylus of third pereiopod, i. fifth pereiopod, j. dactylus of fifth pereiopod, k. male first pleopod, m. male first pleopod, n. male second pleopod, o. posterior portion of telson. b­k, n, o: paratype, male, cl 5.2 mm (FSTC, 92­08­02); m. paratype, male, cl 5.0 mm (FSTC, 92­08­03). Scale bars indicate 1.0 mm (a, e); 0.5 mm (b­d, f, g, i); 0.4 mm (m); 0.3mm (h, j, k, n, o).