Caridina yunnanensis Yu, 1938

Cai, Y. & Ng, P. K. L., 2010, A revision of Caridina yunnanensis and its allied species (Crustacea: Decapoda: Caridea: Atyidae) from Yunnan, southern China, with description of one new species, Journal of Natural History 35 (2), pp. 213-227 : 214-217

Caridina yunnanensis Yu, 1938

( figures 2-4 )

Caridina yunnanensis Yu, 1938: 304 ; figures 15, 16 (type locality: Xundian (Hsun-tien) County, Yunnan); Liang and Yan, 1985: 196.

Material examined

NEOTYPE:, ♂ cl. 4.3 mm ( ZRC. 1998.941 ), Shangyou reservoir , Songming County, Yunnan, southern China.

Other material. Two ♂♂, cl. 5.0- 5.1mm, one ♀, cl. 5.5 mm, one ♀ (ovigerous), cl. 6.0 mm ( ZRC. 1998.921 ); six ♂♂, cl. 4.1-5.1 mm, two ♀♀, cl. 5.2-6.0 mm, one ♀ (ovigerous), cl. 6.0 mm, data same as neotype ( IZAS) .

Description

Rostrum straight or slightly curved downwards, nearly reaching to base of third segment of antennular peduncle or to end of this segment, rostral formula: 5-9 + 4-10/2-10 (3-7), more widely spaced anteriorly than posteriorly; inferior orbital angle of carapace fused with antennal spine; pterygostomial angle subrectangular.

Abdomen with sixth somite 0.4 times as long as carapace, 1.8 times as long as fi fth somite. Telson ending in median projection; five pairs of dorsal spinules, one pair of dorso-lateral spines near distal end, four or nine pairs of setae on distal margin, lateral pair slightly longer than intermediate pairs; preanal carina rounded, unarmed.

Eyes well developed. Antennular peduncle stout, 0.56-0.66 times as long as carapace, basal segment slightly longer than length of peduncle, second segment longer than the third; stylocerite not reaching end of basal segment of antennular peduncle. Scaphocerite 3.4 times as long as wide. Branchial formula normal, with arthropod of second maxilliped poorly developed. Epipods present on first four pereiopods.

Incisor process of mandible ending in irregular teeth, molar process truncated. Lower lacinia of maxillula broadly rounded, upper lacinia elongate, with a number of teeth on inner margin, palp slender. Upper endites of maxilla subdivided, palp short, scaphognathit e tapering posteriorly with some long, curved setae at posterior end. Palp of first maxilliped broadly triangular. Second maxilliped typical of genus. Third maxilliped reaching slightly beyond end of antennular peduncle, ending in a single terminal claw, ultimate segment longer than penultimate segment.

First pereiopod reaching to end of basal segment of antennular peduncle; chela 2.0 times as long as broad, fi ngers 1.2 times as long as palm; carpus shorter than chela, 2.0 times as long as high, merus 3.6 times as long as broad, 1.3 times as long as carpus. Second pereiopod slender, reaching to end of antennular peduncle, chela 3.0-3.3 times as long as broad; fi ngers 1.3 times as long as palm; carpus 4.3-5.0 times as long as high; merus as long as carpus. Third pereiopod reaching end of antennular peduncle, dactylus terminating in two claws, six to eight accessory spines on fl exor margin; propodus 4.0-4.5 times as long as dactylus (terminal spine included), 9-10 times as long as broad, numerous spinules on posterior margin. Fifth pereiopod reaching to end of second segment of antennular peduncle; dactylus stout, 37-43 spinules on fl exor margin; propodus slender, 3.8-4.5 times as long as dactylus, 11-12 times as long as broad.

Endopod of male first pleopod extending to 0.7 times exopod length, sub-elliptical, 2.8-3.0 times as long as broad, inner margin straight, outer margin slightly convex, simple setae longer on exterior margin, longest along anterior margin. Apendix interna on distal one-third, reaching beyond distal margin of endopod. Appendix masculina of male second pleopod reaching to 0.6 times endopod length, armed on inner edge with two rows of strong spines; appendix interna on basal one-third, 0.33 times as long as appendix masculina. Uropodal diaeresis with 13-14 spinules. Eggs 1.20- 1.28 ✕ 0.75-0.85 mm in diameter.

Habitat

Mountain stream ( Yu, 1938), reservoir (present study).

Distribution

Xundian and Songming Counties, Yunnan ( figure 1 ).

Remarks

Yu (1938) described Caridina yunnanensis in some detail on the basis of two male and seven female specimens from a mountain stream at Hsun-Tien (Xundian) County in Yunnan Province. According to Yu, his material was kept in the Fan Memorial Institute of Biology, the forerunner of the present-day Institute of Zoology, Academia Sinica, Beijing ( IZAS). His specimens cannot be located in the IZAS (also A. Dai, personal communication). They are also not present in the research station in Qingdao and Beijing Natural History Museum ( R. Liu, X. Li and S. L. Yang, personal communication). The type specimens of C. yunnanensis Yu, 1938 , are here regarded as lost.

Because C. yunnanensis is the first member of the species group described and its accurate identity is critical to resolving the taxonomy of the other members of the group, a neotype is critically needed. A male specimen (cl. 4.3 mm, ZRC.1998.941) collected from Shangyou Reservoir in Songming County, Yunnan, is here designated the neotype of C. yunnanensis .

We have been unable to obtain specimens from the original type locality of C. yunnanensis in Xundian County. The present locality in Songming County shares the same drainage as the adjacent Xundian County , and we are con fi dent that the same species occurs in both areas. The neotype and other 14 specimens from the new type locality agree well with the description and figures of the species by Yu (1938), although the form of rostrum and male first pleopod is more variable than he reported. The rostrum of the present specimens is variable in length, from reaching to the end of the second segment of the antennular peduncle (n = 4), to extending beyond it (n = 4), and even to the end of the antennular peduncle itself (n = 7). The appendix interna of the male first pleopod reaches to slightly beyond the distal margin of the endopod (n = 2) to well beyond it (n = 4).

Figures

FIG. 2. Caridina yunnanensis. (A) Cephalothorax; female, cl. 6.0 mm (IZAS); (B) cephalothorax, male, cl. 5.1 mm (IZAS); (C) mandible; (D) maxillula; (E) maxilla; (F) first maxilliped; (G) second maxilleped; (H) third maxilliped. Scales: A, B, E, H = 1mm; C, D, F, G = 0.5 mm.

FIG. 3. Caridina yunnanensis. (A) Cephalothorax; male, cl. 4.3 mm (neotype, ZRC.1998.941); (B) cephalothorax, male cl. 4.5 mm (IZAS); (C) scaphocerite; (D) first pereiopod, female; (E) second pereiopod, female; (F) third pereiopod; (G) dactylus of third pereiopod; (H) fifth pereiopod; (I) dactylus of fifth pereiopod. Scales: A-F, H = 1 mm; G, I = 0.5 mm.

FIG. 4. Caridina yunnanensis. Male, cl. 5.1 mm (IZAS). (A) Antennular peduncle; (B) telson; (C) distal portion of telson; (D) first pereiopod; (E) second pereiopod; (F) endopod of male first pleopod, cl. 4.5 mm (IZAS); (G) endopod of male first pleopod, cl. 5.1 mm (IZAS); (H) masculina of male second pleopod, cl. 5.1 mm (IZAS); (I) uropodal diaeresis. Scales: A-E = 1 mm, C, F, G, H, I = 0.2 mm.

FIG. 1. Distribution of Caridina yunnanensis species group.