Caridina huangi Hou, Zhang & Guo, 2025

Hou, Junjie, Zhang, Jiping, Chen, Bing, Zhang, Yixuan, Chen, Wenjian & Guo, Zhaoliang, 2025, Integrative taxonomy reveals the Caridina clinata Cai, Nguyen & Ng, 1999 species complex (Crustacea, Decapoda, Atyidae), with descriptions of eight new species from Hainan Island, China, Zoosystematics and Evolution 101 (4), pp. 2295-2336 : 2295-2336

Caridina huangi Hou, Zhang & Guo sp. nov.

Figs 2 E , 11 , 12

Materials examined.

China – Hainan Island • Holotype: 1 ♂, cl 4.1 mm, ( FU 5727001 ), Qiongzhong County, 18°56'39"N, 109°57'1"E, al. 242 m, stn. 8, coll. WANG A. and HOU J. J., 17 Jan. 2024 .

Paratypes. 1 ♂, cl 4.2 mm, ( FU 5727002 ); 1 ♂, cl 4.4 mm, ( FU 5727003 ); 1 ♂, cl 4.4 mm, ( FU 5727004 ); 2 ♂♂, cl 4.1–4.7 mm, ( FU 5727007 ); 1 ♀, cl 4.5 mm, ( FU 5727005 ); 1 ovigerous ♀, cl 4.6 mm, ( FU 5727006 ), same collection data as holotype .

Description.

Body (Fig. 2 E ): Small, slender and sub-cylindrical, males up to 4.7 mm cl, females up to 4.6 mm cl. Sixth abdominal somite 0.46–0.52 times as long as carapace.

Rostrum (Fig. 11 A ): Short, straight, reaching to the end of the first segment to the middle of the second segment of antennular peduncle; 0.2–0.5 of cl; armed dorsally with 9–15 teeth, including 3–5 on carapace posterior to orbital margin, ventrally with 0–2 teeth; rostral formula 3–5 + 6 – 10 / 0 – 2; lateral carina dividing rostrum into two unequal parts, continuing posteriorly to orbital margin.

Eyes (Fig. 11 A ): Well-developed, on short ocular peduncle, cornea globular.

Carapace (Fig. 11 A ): Smooth, glabrous; antennal spine acute, fused with inferior orbital angle; pterygostomian margin broadly rectangular, slightly produced forward; pterygostomian spine absent.

Antennule (Fig. 11 B ): Stylocerite reaching 1.19–1.31 times as long as basal segment of antennular peduncle; basal segment shorter than combined length of second and third segments, 1.32–1.53 times as long as second segment; second segment 1.20–1.45 times as long as third segments; all segments with marginal plumose setae.

Antenna (Fig. 11 C ): Scaphocerite 3.0–3.3 times as long as wide, outer margin straight, asetose, ending in a strong sub-apical spine, inner and anterior margins with long plumose setae.

First maxilliped (Fig. 11 G ): Palp of first maxilliped broadly triangular, ending in finger-like projection.

Third maxilliped (Fig. 12 B ): Basal segment 0.94–1.21 times as long as penultimate segment; penultimate segment 0.92–1.00 times as long as distal segment, ending in a large claw-like spine surrounded by simple setae, preceded by 5–6 thin spines on distal third of posterior margin, proximally a clump of long and short simple, serrate setae; exopod reaching beyond the middle of second segment, distal margin with long plumose setae.

First pereiopod (Fig. 12 C ): Chela 2.00–2.33 times as long as high, 1.30–1.44 times as long as carpus; movable finger 2.41–3.00 times as long as wide and 0.80–1.21 times as long as palm, setal brushes well developed; carpus 1.51–2.40 times as long as wide, slightly excavated distally; merus 1.03–1.21 times as long as carpus.

Second pereiopod (Fig. 12 D ): Chela 2.44–2.92 times as long as high, 0.75–0.86 times as long as carpus; movable finger 3.87–4.79 times as long as wide and 1.10–1.54 times as long as palm, setal brushes well-developed; carpus 4.78–5.45 times as long as wide, slightly excavated distally; merus 0.79–1.03 times as long as carpus.

Third pereiopod (Fig. 12 E ): Dactylus 3.22–3.81 times as long as wide, terminating in a prominent claw-like spine surrounded by simple setae, followed by 4–6 spiniform setae; propodus 3.29–4.44 times as long as dactylus, 8.32–10.25 times as long as wide; carpus 0.58–0.79 times as long as propodus; merus 1.79–2.25 times as long as carpus, with 3 spiniform setae on posterior margin.

Fourth pereiopod: Proportion and spination similar to third pereiopod.

Fifth pereiopod (Fig. 12 F ): Dactylus 3.27–4.85 times as long as wide, ending in prominent claw-like spine surrounded by simple setae, followed by a row of 41–49 spiniform setae; propodus 3.35–3.62 times as long as dactylus, 11.22–13.12 times as long as wide; carpus 0.48–0.73 times as long as propodus; merus 1.48–1.86 times as long as carpus, with 2–3 spiniform setae on the posterior margin.

First four pereiopods with epipod.

First pleopod (Fig. 12 G ): Endopod in male 0.44–0.46 times as long as exopod, oblong-reniform, 2.40–2.80 times as long as distally wide, tip rounded, inner margin slight concave, outer margin slightly convex, long pappose setae on outer and distal margins, medium-length setae on inner margin; appendix interna well-developed, arising from distal 0.33 of endopod, reaching slightly beyond end of endopod, distally with cincinuli.

Second pleopod (Fig. 12 H ): Appendix masculina rod-shaped, reaching 0.59–0.67 times length of exopod, some short spiniform setae on basal part, and inner margin and tip bearing nearly equal long and stout spiniform setae; appendix interna well developed, reaching 0.49–0.55 length of appendix masculina, distally with cincinuli.

Telson (Fig. 12 I ): Tapering posterior, with a projection, with 5 pairs of short spiniform setae dorsally and one pair of short spiniform setae dorsolaterally; posterior margin with 4 pairs of intermedial spiniform setae. Exopodite of the uropod (Fig. 12 J ) bears a series of 19–26 movable spinules along diaresis.

Eggs: 0.66–0.85 mm × 1.10–1.27 mm in diameter.

Remarks.

Caridina huangi sp. nov. resembles C. pacbo Do, von Rintelen & Dang, 2020 (distributed in Cao Bang Province, Vietnam) in the form and armature of the rostrum, the long stylocerite, the proportions between the joints of pereiopods, and also in the coloration and pattern. However, the new species can be distinguished from C. pacbo by the slender scaphocerite (3.0–3.3 times as long as wide vs. 2.64–3.13 times in C. pacbo ); more spinules on the uropodal diaeresis (19–26 spinules vs. 19–20 in C. pacbo ); the slightly broader endopod of the first male pleopod (2.40–2.80 times as long as wide vs. 2.90–3.30 in C. pacbo ); The long spiniform setae on the distal surface are more dense on the appendix masculina of male second pleopod (The long spiniform setae on the distal surface are more sparse on the appendix masculina of male second pleopod in C. pacbo ).

Caridina huangi sp. nov. is most similar to C. mongziensis Liang, Yan & Wang, 1987 (distributed in Mongzi, Yunnan Province) in the shape of the sexual appendages and telson, the long stylocerite, and the proportions between the joints of the pereiopods, although no material of C. mongziensis was available for the molecular phylogenetic analysis in this study. This new species can be easily distinguished from C. mongziensis by the slender scaphocerite (3.0–3.3 times as long as wide vs. 2.9–3.0 times in C. mongziensis ); the slender propodus of the fifth pereiopod (11.22–13.12 times as long as wide vs. 9.8 times in C. mongziensis ) and more spiniform setae on the flexor margin of the dactylus (41–49 spiniform setae vs. 35–40 spiniform setae in C. mongziensis ); the more spinules on the uropodal diaeresis (19–26 spinules vs. 13–18 in C. mongziensis ); and the small eggs (0.66–0.85 × 1.10–1.27 mm vs. 0.93–1.07 × 1.35–1.59 mm in C. mongziensis ).

In terms of the long stylocerite, the rostral morphology and armature, Caridina huangi sp. nov. closely resembles C. qiongzhongensis sp. nov. (see remarks under C. qiongzhongensis sp. nov.).

Molecular results.

The intraspecific p-distances of COI of the new species were 0 % – 0.4 %. The new species is most similar in genetic divergence (p-distance) to C. brevilineata sp. nov. (6.0 %) and C. hepingensis sp. nov. (6.4 % – 6.6 %). According to molecular analysis, the distance between the new species and C. clinata is 11.1 % – 11.8 %. The intraspecific p-distances of 16 SrRNA of the new species were 0 %. The new species is most similar in genetic divergence (p-distance) to C. hepingensis sp. nov. (1.6 %) and C. qiongzhongensis sp. nov. (2.2 % – 2.5 %). According to molecular analysis, the distance between the new species and C. clinata is 3.6 % – 4.6 % (Fig. 21 , Suppl. materials 1, 2).

Coloration.

Body translucent. The surface of the cephalothorax is covered with fine spots. The middle part of the abdominal carapace has a row of small spots, and the abdominal margin has 3–4 fine vertical stripes. (Fig. 2 E ).

Etymology.

The new species is named after its discoverer Mr. Huang.

Ecological notes.

C. huangi sp. nov. was collected from site 8. At site 8, the stream measured 0.5–1.0 m in width and 0.3–0.5 m in depth, and its substrate consisted of rock, leaf litter, and aquatic plants. The shrimps lived densely among leaf litter and marginal vegetation, exhibiting high population density. The stream water was intermediately flowing (Fig. 2 E , Table 1 ).

Distribution.

Only occurring in Heping Town, Qiongzhong County, Hainan Island.

Figures

Figure 2. Habitats of 9 Caridina species on Hainan Island. A. C. clinata Cai et al., 1999; B. C. caii sp. nov.; C. C. wenchangensis sp. nov.; D. C. qiongzhongensis sp. nov.; E. C. huangi sp. nov.; F. C. hepingensis sp. nov.; G. C. fontinalis sp. nov.; H. C. tunchengensis sp. nov.; I. C. brevilineata sp. nov.

Figure 11. Caridina huangi Hou, Zhang & Guo, sp. nov. A. Holotype male (FU 5727001); B – G. Paratype male (FU 5727002): A. Cephalothorax; B. Antennular; C. Antenna; D. Mandible; E. Maxillula; F. Maxilla; G. First maxilliped.

Figure 12. Caridina huangi Hou, Zhang & Guo, sp. nov. A – J. Paratype male (FU 5727002): A. Second maxilliped; B. Third maxilliped; C. First pereiopod; D. Second pereiopod; E. Third pereiopod; F. Fifth pereiopod; G. First pleopod of the male; H. Second pleopod of the male; I. Telson; J. Uropodal diaeresis.

Figure 21. Maximum likelihood method (ML) tree of 8 new species of Caridina and other atyids and 1 Macrobrachium species, based on the analysis of two mitochondrial gene fragments. Numbers on branches show ML bootstrap values (> 70). The scale bar indicates the substitution rate. The code following the species name is the specimen code.