Phalloceros leptokeras, Lucinda, 2008

Lucinda, Paulo Henrique Franco, 2008, Systematics and biogeography of the genus Phalloceros Eigenmann, 1907 (Cyprinodontiformes: Poeciliidae: Poeciliinae), with the description of twenty-one new species, Neotropical Ichthyology 6 (2), pp. 113-158 : 126-128

Phalloceros leptokeras , new species

Figs. 15-17

Phalloceros sp. n. F Lucinda & Reis (2005).

Holotype. MNRJ 23606, rio São Francisco, tributary to rio Paquequer, Fazenda São Francisco de Paula, approximately 22 o 2’S 42 o 47’W, Sapucaia, Rio de Janeiro, Brazil, 6Aug 1990, D.A. Halboth etal.

Paratypes. BRAZIL. Rio de Janeiro. MCP 30512, 6/4* and MNRJ 22509, 36, collected with the holotype. MCP 13736, 3, rio São Francisco II, on road from Além Paraíba to Teresópolis, 9 Sep 1989, C.A.S. Lucena et al. MNRJ 14497, 8, Teresópolis, rio Paquequer on road BR 116, upstream Teresópolis, 17 Feb 1990. MNRJ 15525, 2, Teresópolis, córrego Brejal, under bridge at Fazenda Rio Bonito, 17 Oct 1989, D.A. Halboth. MNRJ 22510, 5, Teresópolis, ribeirão Santa Rita (tributary to the left margin of rio Paquequer), near Fazenda Santo Afonso, 11 Mar 1996, P.A. Buckup et al.

Diagnosis. Phalloceros leptokeras can be diagnosed by the following uniquely derived autapomorphy: typical densely pigmented rectangle like lateral spot located on the 14 th or 15 th (very rarely 16 th) scale of longitudinal line [134-5*] ( Fig. 15 ). Furthermore, P. leptokeras is readily distinguished from its congeners, except P. tupinamba and P. aspilos , (1) by the presence a lateral ramus of the female urogenital papilla ( Fig. 16 ); (2) female urogenital papilla left turned ( Fig. 16 ); (3) large sickle like hook on the gonopodial appendix located in its inner surface and close to its base ( Fig. 17 ); and (4) absence of vertical bars along body sides ( Fig. 15 ). Phalloceros leptokeras can be distinguished from P. aspilos by the presence of lateral spot (vs. spot absent). Phalloceros leptokeras can be distinguished from P. tupinamba by the flattened female urogenital papilla (vs. not-flattened in P. tupinamba ) and by the lateral spot densely pigmented, rectangle like, horizontally covering the length corresponding to two or three scales length (vs. normally pigmented, vertically elongated, and horizontally covering the length corresponding to the length of one scale in P. tupinamba ).

Description. Morphometric data in Tables 1 and 2 . Range of SL: 21.7 to 36.5 mm (females), 16.5 to 23.7 mm (males). Dorsal-fin rays: 8* [20]. Branched pectoral-fin rays: 6 [1], 7* [14]. Pelvic-fin rays: 5* [8] (males), 5 [11] (females). Anal-fin rays of females: 11 [11].Anal-fin rays of males: 8 [1], 9* [8]. Branched caudal-fin rays: 10 [1], 11 [3], 12* [10], 13 [1]. Predorsal scales: 14* [10]. Longitudinal series of scales: 28* [7], 29 [9]. Series of scales around caudal peduncle: 16* [20]. Transverse series of scales: 7* [20]. Serrae on R4p: 11 [3], 12 [4], 13 [1], 14 [1]. Epipleural ribs: 12 [1], 13 [3]. Pleural ribs: 14* [2], 15 [1], 16 [1]. Vertebrae: 32 [3], 33 [1]. Female urogenital papilla slightly left turned and with lateral ramus. Female urogenital papilla very flattened. Hooks of gonopodial appendix large and sickle like ( Fig. 17 ).

Color in alcohol. Eye greyish iridescent black with greenish brown pupil. Ground color cream, darker in upper half. Border of scales and subjacent skin replete with brown chromatophores, more concentrated at short distance from scale border, conferring reticulate pattern to body sides, mainly on upper half. Brown chromatophores scattered through whole body, more concentrated on dorsal portion, mainly on head, snout, opercle, and ventral surface of mandible. Lateral spot densely pigmented, rectangle like, horizontally covering two or three scales, located on 14 th or 15 th (very rarely 16 th) scale of longitudinal line. Inconspicuous vertical bars along flanks present or absent. Dorsal-fin membrane hyaline. Faint band of chromatophores on distal border of dorsal fin. Faint band of chromatophores near dorsal-fin base. Pectoral, pelvic, and caudal fins hyaline. Dark brown line along R3. Anal fin of females hyaline; few chromatophores scattered through first three rays but not forming defined patch of pigmentation.

Etymology. From the Greek, λεπτος,−η,−ον [= leptos, é, -ón], adj. masc. nom. sg., meaning strait, narrow plus κερας [= kéras], n. neut. nom. sg. i.f., meaning horn, alluding to the slender gonopodial appendix. Λεπτοκερας ( leptokeras ) is a noun in apposition.

Distribution. Middle portions of rio Paraíba do Sul drainage ( Fig. 18 ).

Remarks. Phalloceros leptokeras is restricted to the middle portions of rio Paraíba do Sul drainage. This species is sympatric and sometimes syntopic with P. harpagos . Phalloceros leptokeras can be easily distinguished from P. harpagos by (1) the hook of gonopodial appendix (large sickle like and located in inner surface of gonopodial appendix and close to its base vs. small and located in the outer surface of gonopodial appendix and near its tip, respectively); (2) female urogenital papillae (left turned and lateral ramus present vs. straight and lacking lateral ramus, respectively); (3) lateral spot (densely pigmented, rectangle like, horizontally covering two or three scales located on the 14 th or 15 th [very rarely 16 th] scale of longitudinal line vs. normally pigmented, vertically elongated, and horizontally covering one scale and located on the 15 th 16 th, 17 th, 18 th or 19 th scale of longitudinal line, respectively); (4) inconspicuous vertical bars along body sides (present vs. absent, respectively).

Figures

Fig. 15. Phalloceros leptokeras. (A) Holotype, male, 22.3 mm SL, MNRJ 23606, rio São Francisco, tributary to rio Paquequer Fazenda São Francisco de Paula, Sapucaia, Rio de Janeiro, Brazil; (B) paratype, female, MNRJ 22509, 33.7mm SL, collected with the holotype.

Fig. 16. Urogenital region of female of Phalloceros leptokeras, MCP 30512.(A) ventral view; (B) lateral view of left side.A = anus; AF = anal fin; PF = pelvic fin; UGP = urogenital papilla. Scale bar 1 mm.

Fig. 17. Gonopodium tip of Phalloceros leptokeras, MCP 30512. (a) ventrolateral view; (b) lateral view. R3, R4a, R4p, R5a, R5p indicate gonopodial rays. H = hook. Scale bar 1 mm.

Fig. 18. Collection localities of Phalloceros elachistos (fivepointed star, 1), P. leptokeras (triangle, 2), P. aspilos (circle, 3), P. alessandrae (inverted triangle, 4), and P. megapolos (square, 5). Some symbols represent more than one lot or locality. Numbers represent type localities. The inset is the range of the genus.