Thursday, April 8, 2021

[Crustacea • 2021] Caridina incolor • Integrative Taxonomy uncovers A New Stygobiotic Caridina Species (Decapoda, Caridea, Atyidae) from Guizhou Province, China

Caridina incolor 
 Feng, Chen & Guo, 2021

Collecting much-needed information on the taxonomy, distribution, and ecology of cave-dwelling shrimp is vital for addressing the urgent challenges in conservation biodiversity in fragile cave ecosystems. Caridina incolor sp. nov., a new atyid shrimp from an underground stream of Yaoshui Cave, Daqikong scenic area, Libo County, Guizhou Province, southwestern China is described based on morphology and DNA analysis (mitochondrial COI). Caridina incolor sp. nov. differs from epigean congeners by its smaller eyes which range from reduced to completely blind; colorless body and appendages; long stylocerite and sixth abdominal segment; and relatively large eggs. In comparison to other cave species, Caridina incolor sp. nov. presents a long rostrum and stylocerite; slender sixth abdominal segment; and unique shape of the appendix masculina. Data on the habitat, ecology, and levels of threat are provided and suggest that it should be categorized as Critically Endangered (CR) under the current IUCN criteria.

Keywords: Caridina, COI, conservation biodiversity, freshwater biodiversity, southwestern China, speleology, taxonomy

Figure 1. Type locality and schematic diagram of the cave of Caridina incolor sp. nov.
A Yaoshui Cave is located near Libo County and is marked by the red dot B the sampling point of shrimp C the sampling point of fish D side view of the cave E plan view of the cave F a pool in a weak light zone G river in the dark zone.

Figure 5. Habitats, variable features, and live coloration of Caridina incolor sp. nov.
 A surrounding environment of Yaoshui Cave during the dry season B same site during the rainy season C–E variable rostrum and eye size in life F ovigerous female in life.

Caridina incolor 

Diagnosis: Body and appendages without coloration, translucent. Rostrum slender, slightly elevated at base, reaching to base of 3rd segment of antennular peduncle to end of scaphocerite; straight, slightly sloping downwards, sometimes with tip turned upwards; rostral formula 6–10+11–27/4–15. First pereiopod carpus 0.83–0.91 × as long as chela, 2.3–2.7 × as long as high; chela 2.2–2.5 × as long as broad; fingers 1.1–1.4 × as long as palm. Second pereiopod carpus 1.3–1.4 × as long as chela, 5.4–5.6 × as long as high; chela 2.4–2.6 × as long as broad; fingers 1.6–1.8 × as long as palm. Third pereiopod propodus 3.8–4.0 × as long as dactylus, 13.6–14.4 × breadth, with 8–11 thin spines on the posterior and lateral margins. Fifth pereiopod propodus 4.0–4.7 × as long as dactylus, 17.6–20.5 × breadth, with 17–20 thin spines on the posterior and lateral margins, dactylus terminating in one claw, with 50–55 spinules on flexor margin. Endopod of male subrectangular, slightly wider proximally, length 0.39–0.46 × exopod length, 2.0–2.2 × proximal breadth, ending broadly rounded; inner margin slightly concave, bearing spine-like setae, outer margin slightly convex, proximally 1/3 bearing nearly equal length short spine-like setae, distally 2/3 bearing nearly equal length long spine-like setae, and top bearing nearly equal length stout spine-like setae; appendix interna well developed, arising from distal 1/3 of endopod, beyond the end of endopod, distally with cincinulli. Appendix masculina rod-shaped and gradually tapering into a triangular tip, reaching about 0.48–0.51 × length of endopod, with numerous long spined setae on proximal and distal regions; endopod reaching about 0.76–0.79 × length of exopod; appendix interna well developed, reaching about 0.58–0.78 × length of appendix masculina, with cincinulli distally. Uropodal diaeresis with 10–12 movable spinules. Females carry 10–15 eggs, size of undeveloped eggs (without eyespots) 0.83–0.88 × 1.18–1.26 mm.

Etymology: Caridina incolor sp. nov. is named after the colorless and transparent body color.

 Shuo Feng, Qing-Hua Chen and Zhao-Liang Guo. 2021. Integrative Taxonomy uncovers A New Stygobiotic Caridina Species (Decapoda, Caridea, Atyidae) from Guizhou Province, China. ZooKeys. 1028: 29-47. DOI: 10.3897/zookeys.1028.63822