Caridina H. Milne Edwards, 1837

Tu, Do Van, Thu, Cao Thi Kim & Rintelen, Thomas Von, 2021, Deep into darkness: the first stygobitic species of freshwater shrimp of the genus Caridina (Crustacea: Decapoda: Atyidae) from Northern Vietnam, Zootaxa 4933 (3), pp. 422-434 : 425

Genus Caridina H. Milne Edwards, 1837

Type species. Caridina typus H. Milne Edwards, 1837, by original designation

Caridina thachlam , sp. nov.

( Figs. 2–5 )

Examined material. Holotype: 1 male, cl 4.2 mm, Vietnam, Thanh Hoa Province, Thach Thanh District, Thach Lam Commune, Bo Village , N 20°21’24.0779” E 105°30’27.347” (cave 1, lower), IEBR–FS–004, 10.v.2019, Do VT, Hoang AT & Dang VD . Paratypes: 4 females, cl 3.5–4.5 mm; 2 males, cl 4.2 mm, ZMB 30337, same data as holotype ; 1 female, cl 4.2 mm; 2 males, cl 3.7–4.2 mm, Vietnam, Thanh Hoa, Thach Thanh, Thach Lam, Bo , (cave 2, higher, site 2), N 20°21’8.214” E 105°31’8.681”, ZMB 300337 , 10.v.2019, Do VT, Dang VD . 5 females, cl 4.3–4.8 mm; 1 male, cl 4.5 mm, Vietnam, Thanh Hoa, Thach Thanh, Thach Lam, Bo , (cave 2, higher, site 1), N 20°21’8.214” E 105°31’8.681”, ZMB 31773, 10.v.2019, Do VT, Dang VD .; 2 males, cl 3.2–3.8 mm; 6 females (incl. one ovigerous), cl 3.0– 4.6 mm, Vietnam, Ninh Binh, Nho Quan, Cuc Phuong, Dang , N 20°16’59.5” E 105°40’37.2”, ZMB 31781, 9.v.2019, von Rintelen T, Do VT, Hoang AT, Dang VD. All caves are located in Cuc Phuong National Park .

Comparative material. Caridina clinata Cai, Nguyen & Ng, 1999 : male, cl 3.1 mm, Vietnam, Ninh Binh, a small stream in Cuc Phuong National Park , N 20°19’11.118’’ E 105°37’42.168’’, ZMB 30664, von Rintelen T & Do VT, 3.iv.2017. Caridina cucphuongensis Dang in Dang, Thai & Pham, 1980: male, cl 3.8 mm; 2 females, cl 4.2–4.4 mm, Vietnam, Ninh Binh, Cuc Phuong National Park , a small stream near the foot path to the one thousand year old tree (Vietnamese name: chò), N 20°21’0.779’’ E 105°36’11.675’’, ZMB 30234, von Rintelen T, Do VT, 03.iv.2017 .

Figures

FIGURE 2. Caridina thachlam, sp. nov.A, Holotype male, cl 4.5 mm (IEBR–FS 004), cephalothorax, lateral view; B, Paratype female, cl 4.5 mm (ZMB 31781, from Dang cave), rostrum and eye, lateral view. C–N, Paratype male, cl 4.2 mm (ZMB 30338), cephalic appendages, lateral view; C, antennular peduncle; D, scaphocerite; E, telson; F, distal portion of telson; G, preanal carina; H, uropodal diaeresis; I, mandible; J, maxillula; K, maxilla; L, first maxilliped; M, distal end of palp of first maxilliped; N, second maxilliped; O, third maxilliped. Scales: A, C, D, E = 1mm; B, F–O = 0.5 mm.

FIGURE 3. Caridina thachlam sp. nov.A–H, J, K, Paratypes male, cl 4.2 mm (ZMB 30338); I, Paratype male, cl 3.7 mm (ZMB 30337). A, first pereiopod; B, second pereiopod; C, third pereiopod; D, dactylus of the third pereiopod; E, fifth pereiopod; F, dactylus of the fifth pereiopod; G, male first pleopod; H, I, endopod of male first pleopod; J, male second pleopod; K, appendix masculina and interna of male second pleopod. Scale: A–K = 0.5 mm.

FIGURE 4. The caves in Bo village (A, B), in Dang village (C) and the entrance of the cave in Bo village (D).

FIGURE 5. Live coloration of Caridina thachlam sp. nov., collected in Dang village (A) and in Bo village (B)