Psilorhynchus pseudecheneis

Conway, Kevin W., 2011, Osteology of the South Asian Genus Psilorhynchus McClelland, 1839 (Teleostei: Ostariophysi: Psilorhynchidae), with investigation of its phylogenetic relationships within the order Cypriniformes, Zoological Journal of the Linnean Society 163 (5), pp. 50-154 : 79

C. Psilorhynchus pseudecheneis

2 mm

its lateral edge. All middle radials are well ossified. In specimens larger than 15.4-mm SL, all distal radial cartilage are ossified endochondrally, and each exhibits a small lateral perichondrally ossified projection at the points of articulation with the base of the associated fin rays. In the two smallest specimens examined (14.0- and 15.3-mm SL), distal radial cartilages are ossified perichondrally around their points of articulation with the base of the associated fin rays. A small endoskeletal ossification, termed the end piece or anal fin stay ( Weitzman, 1962), articulates with the posteroventral edge of the last middle radial. The anal fin stay exhibits a large flange of membrane bone along its posterodorsal surface that projects posteriorly well past the endoskeletal portion of the bone.

Comparisons

The anal fin skeleton of additional species of Psilorhynchus are illustrated in Figure 17B–F. There are few differences between the anal fin skeleton of P. sucatio and the other species of Psilorhynchus examined, except in terms of meristic counts ( Table 1). All other species examined, except for P. balitora , exhibit one additional small unbranched ray in supernumerary association with the first anal fin pterygiophore that is not present in P. sucatio . This small, unbranched ray is variably present in P. balitora . When present it is represented only by a small round nodule of bone.

PECTORAL GIRDLE

Psilorhynchus sucatio

The pectoral girdle of P. sucatio is illustrated in Figures 18A and 19A , and pectoral fin ray counts are provided in Table 1. The cleithrum is the largest bone of the pectoral girdle. It is a large curved bone, extending farthest anteriorly along the ventral midline, where it is tightly bound to its antimere. Ventrally the cleithrum is flattened and plate-like, except for the point of contact with the anterior portion of the coracoid, along its medial edge, where the cleithrum twists dorsally. Dorsally the cleithrum exhibits a shallow groove along its lateral face that accommodates the posteroventral part of the supracleithrum. The supracleithrum is an elongate

Figures

Figure 19. Pectoral radials of Psilorhynchus, left side in lateral view. Anterior to top of page. A, Psilorhynchus sucatio, CAS 50289, 39.9-mm standard length (SL). B, Psilorhynchus balitora, UMMZ 244782, 31.2-mm SL. C, Psilorhynchus breviminor, ZRC 43452, paratype, 32.0-mm SL. D, Psilorhynchus gracilis, UMMZ 205345, paratype, 39.1-mm SL. D, Psilorhynchus robustus, CMK 17941, paratype, 58.1-mm SL. D, Psilorhynchus pseudecheneis, KU 29519, 40.3-mm SL. Cartilage highlighted in grey. Abbreviations: DR, distal radial; DRC, distal radial cartilage; PeR1–4, pectoral radial 1–4.