Macrobrachium lingyunense

Macrobrachium lingyunense (Li & Luo, 2001) Fig. 11 Typhlocaridina lingyune nsis Li & Luo, 2001: 72, fig. 1. Type locality: Sha Cave, Lingyun County, Guangxi, China. Macrobrachium lingyunense Li et al., 2006: 277, figs 1–3; Cai and Ng 2018: 29. Material examined. • 1 male (IBGAS - Dec-Pal- 498-1) (tl 41.2 mm, cl 11.0 mm, rl 5.9 mm) and 2 females (IBGAS - Dec-Pal- 498-2 – 3) (tl 37.6–41.9 mm, cl 10.3–11.1 mm, rl 5.8–6.2 mm), Guangxi, Lingyun County, Sha Cave, 24.4185°N, 106.6123°E, alt. 669 m, 25.XII.2023, Jiang X. K. & Liu Y. W. leg. Distribution. Lingyun County, Guangxi, China. Habitat. A small run-of-river hydropower station has been built at the entrance of Sha Cave, which generates electricity from May to December each year. The cave consists of two layers. The upper layer features intermittent small pools. The lower layer is an underground river with a large water flow. The underground space of Sha Cave is extensive, with scattered large boulders from collapses and soil mounds. Macrobrachium lingyunense was discovered in the pools of the upper level, approximately 500 meters from the cave entrance, located within the dark zone. Remarks. This species differs from all epigean species as well as M. parvum sp. nov. and M. tenuipes by the completely degraded somatic pigmentation and eyes. It can be distinguished from M. elegantum by the tip of rostrum unicuspidate (bifurcate in M. elegantum), the broader scaphocerite (2.2 times longer than wide in M. guizhouense sp. nov. vs. 3.0 in M. elegantum), the different rostral formula (3–4 + 5–7 / 3 – 4 in M. guizhouense sp. nov. vs. 3–4 + 3–4 / 4 – 6 in M. elegantum) and the different ratios between the segments of second pereiopods. This species can be distinguished from M. duanense by the palm of second pereiopods shorter than ischium; from M. lingyunense by the relatively slenderer scaphocerite (2.4 times longer than wide in M. lingyunense vs. 2.2 in M. guizhouense sp. nov.) (Table 4).