Pamphorichthys pertapeh, Figueiredo, 2008

Figueiredo, Carlos Augusto, 2008, A new Pamphorichthys (Cyprinodontiformes: Poeciliidae: Poeciliini) from central Brazil, Zootaxa 1918 (1), pp. 59-68 : 61-66

Pamphorichthys pertapeh , new species

( Fig. 1 )

Holotype. MNRJ 32467 , male. 16,3 mm SL; Brazil: State of Goiás: Municipality of Formosa: lagoa (lake) Perta-Pé at the left side of rio Bezerra , tributary of Preto river , tributary of Paracatu river , São Francisco river basin; Coord. 15°59'02”S 047°11'51”W ( Fig. 2 ); C. A. Figueiredo and D. F. Moraes Jr. 18.Oct.1998.

Paratypes. MNRJ 18090 , locality data as holotype, 49 exs. (10 exs. males 16,7– 14,2 mm SL, 31 exs. females 19,4– 12,7 mm SL, 07 exs. young 13,7– 7,4 mm SL) ; MZUSP 99750 , locality data as holotype, 20 exs. (09 exs. males 15,5– 13,8 mm SL, 08 exs. females 17,2– 13,8 mm SL, 3 exs. young 12,1– 10,5 mm SL) ; MCP 41345, locality data as holotype, 20 exs. (09 exs. males 16,8– 13,4 mm SL, 07 exs. females 17,4– 13,7 mm SL, 04 exs. young 13,4– 10,4 mm SL) ; USNM 393312 , locality data as holotype, 20 exs. (08 exs. males 15,9– 14,5 mm SL, 07 exs. females 17,9– 14,1 mm SL, 05 exs. young 12,9– 10,2 mm SL) ; UF 171129, locality data as holotype, 20 exs. (09 exs. males 17,0–14,0 mm SL, 07 exs. females 18,7– 13,1 mm SL, 04 exs. young 11,8– 09, 3 mm SL) ; UMMZ 248719 , locality data as holotype, 20 exs. (08 exs. males 16,5– 14,6 mm SL, 08 exs. females 16,2– 14,2 mm SL, 04 exs. young 12,4–10,0 mm SL)

Diagnosis. Pamphorichthys pertapeh is distinguished from all other Poeciliinae species by two derived characters, unique among poeciliins: (a) bilobed teeth present on dentary and external tooth row of the premaxilar bone ( Fig. 3 ) and (b) distal-most segments of the anterior branch of the fourth gonopodial ray and of the third gonopodial ray are independently fused into elongated segments ( Fig. 4 ). Other diagnostic characters that are also found in other species of the tribe Poeciliini are: dark longitudinal stripe on female caudal peduncle; urogenital region of females with heavy dark pigmentation; third pelvic-fin ray of males curved distally ( Fig. 5 ); and specialized pair of anal scales anterior to the urogenital opening in females.

Description. Morphometric and meristic data are given for males (table 1) and for females (table 2). Females larger than males.

Dorsal profile of males gently convex from snout to dorsal fin origin, and slightly concave to caudal-fin base. In females, dorsal profile straight on head, gently curved from occipital base to dorsal-fin origin and slightly convex from origin of dorsal fin to caudal-fin base. Ventral profile of males convex on head, with a slight notch between head and pelvis. Pelvic region convex, abruptly angled at the insertion of pelvic fins, presenting a depression between its posterior margin and urogenital papillae, which is attached to the gonopodium. Caudal peduncle convex from gonopodium base to caudal-fin base, with a discrete keel of scales in some males. Ventral profile of females gently convex from head to anal opening with a slightly notch on the opercular borders. A depression occurs between the anus and the base of the anal fin, which is thickened on its first rays. Profile slightly convex from the first rays of the anal fin to the base of the caudal fin. Border of the dorsal fin in both sexes gently curved on distal extremes. Border of caudal fin in both sexes rounded. Border of anal fin is slightly rounded in females, with the third ray being longer than the remaining rays. Pectoral fins rounded and symetrical. Pelvic fins in full-grown males have the second ray elongated and the third ray curved at its subdistal end. Female pectoral fin rays, without any special mophological features, have the second ray being the longest. Gonopodium with a gonopodium palp enveloping its tip and extending beyond the tips of the gonopodium rays.

Dorsal-fin rays i(7) or ii(10)-7(15) or 8(2) (males), i(6) or ii(9)-7(14) or 8(1) (females); anal-fin rays in females iii(15)-9(15); pelvic-fin rays 5(5); caudal-fin branched rays 11(3); unbranched superior caudal-fin rays 6(1) or 7(1); unbranched inferior caudal-fin rays 6(2); pectoral-fin rays 10(1) or 11(2); scales in longitu- dinal series 26(6) or 27(9) (males), 26(3), 27(3), 28(7), and 29(2) (females); scales in transversal series 7(32); scales around caudal peduncle 15(1) or 16(32); pre-dorsal scales 15(5), 16(12), or 17(8). Pre-caudal vertebra 14(6); caudal vertebra 15(6); number of gonapophyses 2(2); first gonapophysis originating at the 14 th (3) vertebra; number of gonactinosts 7(3). Premaxilary teeth on the outer row, males: 6(1), females: 8(1) or 10(1); Dentary teeth on the outer row, males: 6(1) or 7(1); females: 8 (1) or 10(1); first proximal radial of dorsal fin between 11 th and 12 th vertebrae (6); branchiostegal rays 5(5).

Coloration in alcohol. Cream or pale yellow body background color. Scales with dark chromatophore on posterior borders, except those from the abdomen, producing a reticulate pattern. Chromatophore density increased on the dorsal portion of the body, presenting an overall pattern of a darker body seen from above. Abdomen without any sign of scale reticulation. Ventral portion of caudal peduncle with reticulate pattern abruptly lighter, but still present. Horizontal septum region is denser in chormatophores and show a thin irregular stripe more conspicuously posterior to a vertical line passing on the insertion of the first dorsal-fin ray. Ventral portion of dorsal fin with one or two discontinuous dark transversal stripes consisting of horizontal blotches present on the intermembranes of the fin. Dorsal-fin distal tip dark in males. Other fins hyaline, including gonopodium of males. Female urogenital region covered with a very conspicuous dark patch ( Fig. 6 ).

Distribution and habitat notes. Known only from type location, a marginal lake on the left side of Bezerra river, a tributary of the Negro river, tributary of Paracatu river at the São Francisco river basin. Specimens were collected at the lakeshore, which has a sandy bottom, and in clear and shallow waters near grasses and submerged bushes ( Fig. 7).

Etymology. The specific epithet, pertapeh, is an allusion to the type locality, “Lagoa Perta-pé”, which can be translated into “Squeeze-Foot Lake”. The name of the lake refers to the dense aquatic vegetation present in the lake, except for its shore, that makes wading almost impossible. A noun in aposition

Discussion. Species comprising the tribe Poeciliini need to be classified according to their phylogenetic history, and an extensive phylogenetic analysis of the group is still lacking. Although there have been some recent studies on the systematics of the tribe ( Rodriguez, 1997; Ptacek & Breden, 1998; Breden et al., 1999; Hamilton, 2001) its phylogenetic relationships, both internally and with sister groups, have yet to be clarified and many taxonomic revisions are needed. Consequently, generic and supra-generic taxonomy, in many groups of the subfamily, is still unstable.

The species being described here is considered a member of the genus Pamphorichthys . There are currently no diagnostic characters that allow the inclusion of this species in other available Poeciliini genera, as defined by Rodriguez (1997) or Rosen and Bailey (1963). Their definitions of the subgenera of Poecilia were based mainly on superficially examined characters or characters with doubtful polarization.

Pamphorichthys pertapeh is proposed as the sister-group of the remaining species of Pamphorichthys and this relationship is supported by ten shared derived characters: absence of parietal bones, which are also absent in Poecilia reticulata ; shape of the ventral component of the anterior process of the maxilar bone; abrupt shape of the ventral profile of the premaxilar bone; dentary without a lateral process widening the insertion area of the teeth, this process is also absent in Micropoecilia in the sense of Meyer (1993) and Poecilia elegans (Trewavas, 1948) ; forward bending of the median-ventral process in the dentary; process at the endopterigoid connecting to the lateral-ethmoid absent; reduced number of pectoral-fin rays (10-11); second pelvic-fin ray separated from other rays by a deep notch; ventral longitudinal process of the pelvic bones almost imperceptible; number of gonactinosts reduced to seven; gonapophyses parallel to the vertebral spine; Hollister foramen restricted to the anterior tip of the first gonapophysis; and all cephalic sensorial pores substituted by pits with exposed neuromasts.

At least five derived characters are shared by Pseudolimia heterandria , Pamphorichthys pertapeh , and the remaning species of Pamphorichthys: Transverse processes of the parasphenoid not touching the roof of skull; pre-orbital sensorial canal not completely ossified, as in Poecilia reticulata ; reduced number of pectoral-fin rays (<12); anterior insertion of pelvic-fin rays; Hollister foramen on the anterior half of the first gonapophysis.

Four characters are shared by Limia and Pamphorichthys pertapeh : distal portion of the third pelvic-fin ray curved, putatively reversed in Pseudolimia heterandria ; first gonactinost elongated; median segments on the fifth gonopodial ray modified with dorsal projections; a pair of modified scales between anal fin and urogenital opening of females.

Pamphorichthys pertapeh is known only from its type-locality and its highly endemic status places it as an endangered, vulnerable species according to IUCN rules (criterion D2; known occurrence restricted to a small location, i.e. the type-locality). Its description makes it known for biodiversity accounts and conservation efforts, partly revealing an unsuspected morphological diversity and a high level of endemicity not previously known among the species of the Pamphorichthys clade.

Comparative material. Poecilia vivipara: MNRJ 16024 (17 exs.), UFRJ 4091 (04 exs.); Poecilia elegans 23392 (04 ex.), UF 25035 (30 ex.); Limia grossidens: USNM 220524 (paratypes, 82ex.); Pseudolimia heterandria: BMNH 1909.4.2:30-32 (syntypes) (3ex.), CAS 164187 ; Pamphorichthys araguaiensis: UFRJ 1519 (69ex.); Pamphorichthys hasemani: UFRJ 3646 (131ex.); Pamphorichthys hollandi: MZUSP 47356 (273ex.); Pamphorichthys minor: UFRJ 3944 (500ex.), USNM 120268 (02ex. females); Pamphorichthy scalpridens: UFRJ 3914 (362ex.); Micropoecilia branneri: MZUSP 54512 (72ex.), MZUSP 76348 (03ex.); Micropoecilia parae: MZUSP 65428 (117ex.), USNM 66113 (cotype of Acantophacelus melanzonus, 01ex.); Micropoecilia picta: MZUSP 65423 (98ex.), USNM 151459 (04ex.).

Figures

FIGURE 1. Pamphorichthys pertapeh lateral view. (A) Holotype, MNRJ 32467 male, 16,3 mm SL; (B) paratype, MNRJ 18090, female 19,0 mm SL.

FIGURE 2. Geographic position of type locality of Pamphorichthys pertapeh, Perta-Pé lake, Bezerra river, near the region called “Águas Emendadas”, meaning Mended Waters, referring to the confluence of three major neotropical watersheds: A. Tocantins river basin; B. Paraná river basin; C. São Francisco river basin. Dashed line represents watersheds limits.

FIGURE 3. SEM photography of teeth showing outer row of the premaxila with bilobed teeth.

FIGURE 4. Gonopodium of Pamphorichthys pertapeh sp. nov. full view. Scale bar = 1 mm; detailed view in the box of gonopodium tip. Membranous cap represented on the tip of rays 3 and 4a. Scale bar = 1 µm.

FIGURE 5. Urogenital region of female of Pamphorichthys pertapeh showing the pigmented area around anus and urogenital opening. Scale corresponds to 1 mm.

FIGURE 6. Pelvic-fin of sexually mature males Pamphorichthys pertapeh. Scale corresponds to 1 mm.