Cnesterodon Garman, 1895

Lucinda, Paulo H. F., 2005, Systematics of the genus Cnesterodon Garman, 1895 (Cyprinodontiformes: Poeciliidae: Poeciliinae), Neotropical Ichthyology 3 (2), pp. 259-270 : 261-262

Genus Cnesterodon Garman, 1895

Clade [107]

Cnesterodon Garman, 1895: 43 . Gender masculine. Type -species: Poecilia decemmaculata Jenyns, 1842 . Type by original designation.

Gulapinnus Langer, 1913: 207 . Gender masculine. Type -species: Poecilia decemmaculata Jenyns, 1842 . Type by original designation. Junior objective synonym of Cnesterodon Garman.

Diagnosis. Cnesterodon species share the following uniquely derived and unreversed features: (1) anterior tip of basipterygium sinuous in adult males [37-2**]; (2) outer surface of basipterygium base narrow in adult males [39-1**]; (3) haemal arch and spine of vertebrae 13-17 in adult males modified in rudimentary gonapophyses [47-3**]; (4) gonapophysis of vertebra 14 rudimentary in adult males [52- 3**]; (5) distal portion of plural ribs 6, 7, and 8 in adult males expanded [56-1**]; (6) large basal process on first anal-fin proximal radial in adult males [69-2**]; (7) unpaired appendix at tip of R3 [101-1**]; (8) distal segment at tip of R5a transformed in retrorse triangular spine [122-1**]; (9) dark spot posterior to anal-fin base of males continuous ventrally side by side and continuous with ventral median line of caudal peduncle [139-1**].

Additionally, the genus Cnesterodon is diagnosed by the following not uniquely derived and/or reversed features: (1) preopercular canal absent or opened in a shallow groove [8- 1]; (2) posterior border of basipterygium anterior to posterior border of chleitrum [35-3]; (3) width of first pelvic-fin ray in adult males decreasing abruptly at distal portion, distal slender portion short [41-2]; (4) second pelvic-fin ray unbranched in adult males [42-1]; (5) ligastyle absent [46-0]; (6) absence of well-developed gonapophyses [48-0]; (7) functional gonapophyses absent [49-0]; (8) pleural rib 7 longer than pleural rib 8 in adult males [57-1]; (9) first proximal radial of dorsal fin in adult males located between neural spines of 12th and 13th vertebrae [62-0]; (10) gonactinost complex relative to body longitudinal axis very inclined backwards, forming a less than 45º angle with body longitudinal axis [68-0]; (11) fusion of anal-fin posterior median radials (5th to last) to respective proximal radials in adult males [77-1]; (12) lateral process on base of fifth median anal-fin radial very large in adult males [79-2]; (13) nine anal-fin rays in males [85-4]; (14) dorsal expansion present on R5p [124-1]; (15) more distal elements of branches of R6 totally fused [127-2]; (16) hypural plate completely fused [131-0]; and (17) absence of orbital bones [143-0].

Composition. Nine species: Cnesterodon decemmaculatus Jenyns,1842 ; C. carnegiei, Haseman, 1911 ; C. brevirostratus Rosa & Costa, 1993 ; C. septentrionalis Rosa & Costa, 1993 ; C. omorgmatos Lucinda & Garavello, 2001 ; C. hypselurus Lucinda & Garavello, 2001 ; C. raddai Meyer & Etzel, 2001 ; C. iguape sp. nov., and Cnesterodon sp.B , a new species being described by J. Anza, P. Lucinda, and L. Malabarba.

Distribution. Rio Uruguay drainage, laguna dos Patos system, río Negro, río Salado, western drainages of Argentina and small coastal drainages of Uruguay and Argentina, upper portions of the rio Iguaçu and its upper tributaries, the headwaters of the rio Maquiné in the Tramandaí system, and the headwaters of rio Itajaí -Açu drainage, upper rio Araguaia drainage, rio Paranapanema basin, rio Paraguay and lower rio Paraná drainages, upper rio Iporanga tributary of the rio Ribeira do Iguape ( Fig. 1 ).

Remarks. Apparently Garman (1895) erected Cnesterodon based on immature male individuals judging from his figures. He stated: “As seen in Plate VIII., figs. 16 and 17, the modification of the anal fin of the male differs from that of both Glaridodon and Girardinus , in Plate VIII. Figs. 13 -15, and approaches that of Gambusia.” Garman (1895) also synonymized Girardinus iheringii [= Phalloptychus iheringii ] and Girardinus caudimaculatus [= Phalloceros caudimaculatus ] with Girardinus januarius and placed the latter in his new genus Glaridodon . It is evident from Garman’s figure of a male Glaridodon januarius (Plate VIII, fig. 15) showing a distal appendix on gonopodium, that he had only Phalloceros specimens at hand. Then, we conclude that Garman proposed Cnesterodon when comparing immature males with Phalloceros adult males. Further, Garman stated: “In the specimens dissected there were no subvertebral processes for support of the anal fin” [= gonapophyses], Plate VIII, fig. 16, which left no doubt that he actually had Cnesterodon specimens at hand.

Phillipi (1906) placed P. decemmaculata in the genus Glaridichthys , a replacement name for Glaridodon (preoccupied in Dinosauria). Phillipi (1908) considered Girardinus caudimaculatus as a junior synonym of Glaridichthys januarius, but judging from his figures he had solely examined specimens of the first species. Langer (1913) has similarly confused the situation. Based on gonopodium differences, Langer created Gulapinnus for his Glaridichthys decemmaculatus. Therefore, Gulapinnus is a junior synonym of Cnesterodon .

Figures

Fig. 1. Collection localities of Cnesterodon species: C. septentrionalis (eight-pointed stars, 1), C. hypselurus (triangles, 2), C. iguape (five-pointed stars, 3), C. omorgmatus (cross, 4), C. carnegiei (lozenges, 5), C. raddai (pentagons), C. brevirostratus (circles, 6), and C. decemmaculatus (squares, 7). Some symbols represent more than one lot or locality. Numbers represent type localities.