Caridina tunchengensis Hou, Chen & 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

publication ID	https://doi.org/10.3897/zse.101.172207
publication LSID	lsid:zoobank.org:pub:55065651-D7CD-46B2-AB9E-B53611DD38A5
DOI	https://doi.org/10.5281/zenodo.17651083
persistent identifier	https://treatment.plazi.org/id/0779195C-5441-5BC9-8730-BFB71541D327
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Caridina tunchengensis Hou, Chen & Guo
status	sp. nov.

Treatment

Caridina tunchengensis Hou, Chen & Guo sp. nov.

Figs 2 H View Figure 2 , 17 View Figure 17 , 18 View Figure 18

Materials examined.

China – Hainan Island • Holotype: 1 ♂, cl 3.9 mm, ( FU 5700001 ), Tuncheng Town , Tunchang County, 19°28'23"N, 110°6'21"E, al. 181 m, stn. 11, coll. WANG G. Y. and HOU J. J., 18 Jan. 2025 GoogleMaps .

Paratypes: 1 ♂, cl 4.2 mm, ( FU 5716002 ); 1 ♂, cl 3.8 mm, ( FU 5716003 ); 1 ♂, cl 3.7 mm, ( FU 5716004 ); 1 ♂, cl 4.3 mm, ( FU 5716005 ); 1 ♀, cl 3.9 mm, ( FU 5716006 ), 1 ovigerous ♀, cl 4.4 mm, ( FU 5716007 ), same collection data as holotype GoogleMaps .

Description.

Body (Fig. 2 H View Figure 2 ): Small, slender and sub-cylindrical, males up to 4.3 mm cl, females up to 4.4 mm cl. Sixth abdominal somite 0.40–0.51 times as long as carapace.

Rostrum (Fig. 17 A View Figure 17 ): Short, straight, reaching from not beyond the eye to beginning of second segment of antennular peduncle; 0.2–0.3 of cl; armed dorsally with 3–13 teeth, including 0–5 on carapace posterior to orbital margin, ventrally with 1–2 teeth; rostral formula 0–5 + 3 – 8 / 1 – 2; lateral carina dividing rostrum into two unequal parts, continuing posteriorly to orbital margin.

Eyes (Fig. 17 A View Figure 17 ): Well-developed, on short ocular peduncle, cornea globular.

Carapace (Fig. 17 A View Figure 17 ): Smooth, glabrous; antennal spine acute, fused with inferior orbital angle; pterygostomian margin broadly rectangular, slightly produced forward; pterygostomian spine absent.

Antennule (Fig. 17 B View Figure 17 ): Stylocerite reaching 0.79–0.90 times as long as basal segment of antennular peduncle; basal segment shorter than combined length of second and third segments, 1.46–1.74 times as long as second segment; second segment 1.16–1.40 times as long as third segments; all segments with marginal plumose setae.

Antenna (Fig. 17 C View Figure 17 ): Scaphocerite 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. 17 G View Figure 17 ): Palp of first maxilliped broadly triangular, ending with no finger-like projection.

Third maxilliped (Fig. 18 B View Figure 18 ): Basal segment 1.07–1.17 times as long as penultimate segment; penultimate segment 0.97–1.02 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 the middle of second segment, distal margin with long plumose setae.

First pereiopod (Fig. 18 C View Figure 18 ): Chela 1.79–2.26 times as long as high, 1.21–1.34 times as long as carpus; movable finger 2.08–2.77 times as long as wide and 0.71–1.33 times as long as palm, setal brushes well developed; carpus 1.38–1.85 times as long as wide, slightly excavated distally; merus 1.03–1.11 times as long as carpus.

Second pereiopod (Fig. 18 D View Figure 18 ): Chela 2.22–3.15 times as long as high, 0.66–0.76 times as long as carpus; movable finger 2.85–4.37 times as long as wide and 1.07–1.47 times as long as palm, setal brushes well developed; carpus 5.17–5.66 times as long as wide, slightly excavated distally; merus 0.88–0.99 times as long as carpus.

Third pereiopod (Fig. 18 E View Figure 18 ): Dactylus 2.95–3.96 times as long as wide, terminating in a prominent claw-like spine surrounded by simple setae, followed by 5–7 spiniform setae; propodus 3.04–4.24 times as long as dactylus, 8.13–10.05 times as long as wide; carpus 0.67–0.82 times as long as propodus; merus 1.42–1.96 times as long as carpus, with 3 spiniform setae on the posterior margin. Ischium sometimes with 1 small movable spiniform setae on the posterior margin.

Third and fourth pereiopods with 1 spine on ischium.

Fifth pereiopod (Fig. 18 F View Figure 18 ): Dactylus 3.37–4.62 times as long as wide, ending in prominent claw-like spine surrounded by simple setae, followed by a row of 36–42 spiniform setae; propodus 3.37–4.18 times as long as dactylus, 9.63–12.61 times as long as wide; carpus 0.51–0.61 times as long as propodus; merus 1.42–1.63 times as long as carpus, with 3 spiniform setae on the posterior margin.

First pleopod (Fig. 18 G View Figure 18 ): Endopod reaching 0.42–0.45 times as long as exopod, oblong-reniform, 2.46–2.58 times as long as distally wide, terminal width subequal to basal width; inner margin concave, outer margin convex, long pappose setae on outer and distal margins, medium-length setae on inner margin; appendix interna well developed, arising from distal 0.2 of endopod, reaching slightly beyond the end of endopod, distally with cincinuli.

Second pleopod (Fig. 18 H View Figure 18 ): Appendix masculina rod-shaped, reaching 0.63–0.64 length of endopod; with some short spiniform setae on outer surface and some long and stout spiniform setae on distal surface; appendix interna reaching 0.50–0.56 length of appendix masculina.

Telson (Fig. 18 I View Figure 18 ): With 4 pairs of short spiniform setae dorsally and one pair of short spiniform setae dorsolaterally; posterior margin triangular, with 3–4 pairs of intermedial plumose setae, lateral plumose setae slightly longer, intermediate plumose setae subequal. Exopodite of the uropod (Fig. 18 J View Figure 18 ) bears a series of 17–22 movable spinules along diaresis.

Eggs: 0.71–0.78 mm × 1.09–1.23 mm in diameter.

Remark.

Caridina tunchengensis sp. nov. is similar to C. clinata Cai et al., 1999 , but differs by: shorter and stouter endopod of first pleopod (length 2.46–2.58 times width vs. 2.40–3.04 times in C. clinata ); fewer dorsal and ventral rostral teeth (3–13 dorsal, 1–2 ventral vs. 12–21 dorsal, 1–5 ventral in C. clinata ); fewer spiniform setae on fifth pereiopod dactylus (36–42 spiniform setae vs. 41–51 spiniform setae in C. clinata ); absence of digitiform process on first maxilliped exopod (present in C. clinata ); palp of first maxilliped (ending with no finger-like projection vs. ending with a finger-like projection in C. clinata ).

Caridina tunchengensis sp. nov. is similar to C. fontinalis sp. nov., but differs by: shorter first pleopod endopod (0.42–0.45 times as long as exopod vs. 0.49–0.61 times as long as exopod in C. fontinalis sp. nov.); more uropodal exopod spines (17–22 vs. 12–16 in C. fontinalis sp. nov.); fewer merus spines on third and fifth pereiopods (3 vs. 3–5 in C. fontinalis sp. nov.); palp of first maxilliped (absence of digitiform process on first maxilliped exopod vs. with a digitiform process on first maxilliped exopod in C. fontinalis sp. nov.).

Molecular results.

According to the COI sequence, the intraspecific p-distances of COI of the new species were 0 % – 0.2 %. The new species is most similar in genetic divergence (p-distance) to C. fontinalis sp. nov. (5.3 % – 5.7 %) and C. wenchangensis sp. nov. (9.1 % – 9.4 %). According to molecular analysis, the distance between the new species and C. clinata is 9.4 % – 9.6 %. According to the 16 SrDNA sequence, the intraspecific p-distances of 16 SrDNA of the new species were 0.4 % – 1.1 %. The new species is most similar in genetic divergence (p-distance) to C. fontinalis sp. nov. (1.6 % – 2.7 %) and C. clinata (2.7 % – 3.2 %). According to molecular analysis, the distance between the new species and C. wenchangensis sp. nov. is 5.6 % – 5.8 % (Fig. 21 View Figure 21 , Suppl. materials 1, 2).

Coloration.

Eyes reddish-brown; body translucent; posterior carapace margin with a black longitudinal stripe; mid and posterior abdominal segments with faint black speckles. (Fig. 2 H View Figure 2 ).

Etymology.

The name is derived from its type locality, Tuncheng Town.

Ecological notes.

C. tunchengensis sp. nov. was collected from site 11. At site 11, the stream measured 0.5–1.0 m in width and 0.2–0.3 m in depth, and its substrate consisted of rock, mud, leaf litter, and aquatic plants. The shrimps lived among leaf litter and marginal vegetation, exhibiting high population density. The stream water was slow-flowing (Fig. 2 H View Figure 2 , Table 1 View Table 1 ).

Distribution.

Only occurring in the type locality, Tuncheng Town, Tunchang County, Hainan Island.