Petilipinnis grunniens ( Schomburgk, 1843 )

Casatti, Lilian, 2002, Petilipinnis, A New Genus For Corvina Grunniens Schomburgk, 1843 (Perciformes, Sciaenidae) From The Amazon And Essequibo River Basins And Redescription Of Petilipinnis Grunniens, Papéis Avulsos de Zoologia 42 (7), pp. 169-181 : 171-174

Petilipinnis grunniens ( Schomburgk, 1843)

( Figs. 1-2 )

Corvina grunniens Schomburgk, 1843: 136 , pl. 2 (original description; type locality: British Guiana [ Guyana], Essequibo River ).

Pachypops grunniens Jordan & Eigenmann, 1889: 414 (name only); Eigenmann, 1912: 476 (freshwater fishes of British Guiana [ Guyana]).

Pachyurus grunniens Chao, 1978: 43 (Western Atlantic Sciaenidae ).

MATERIAL EXAMINED

63 specimens. Guyana: Essequibo: Essequibo River, upstream Kurupukari , ANSP 176038, 10(33.9-102.5), 27.I.1997, W.G. Saul col.; Essequibo River, upstream Maipure , ANSP 176039, 5(22.6-51.7), 02.II.1997, W.G. Saul col.; Essequibo River , ANSP 176040, 1(50.7), 31.I.1997, W.G. Saul col.; ANSP 176041, 1(77.5), 26.I.1997, D.Torres col.; ANSP 176042, 2(90.3-107.7), 25.I.1997, W.G. Saul col.; ANSP 176043, 1(252.0), 27.I.1997, W.G. Saul col.; AMNH 215024, 5(49.2-69.6), 1935, A.S. Pinkus col.; AMNH 220463, 1(140.9), 09.XII.1937, T. Holden col.; Essequibo River, Kartabo , AMNH 220423, 1(34.0), 12.IV.1924, Beebe col.; AMNH 220438, 4(62.7-95.6), 05.VI.1924, Beebe col.; Potaro River, Tumatumari , FMNH 53957, 1(132.7), 1908, C.H. Eigenmann col.; Unorowo River, branch of Essequibo River , AMNH 220483, 2(176.0-202.4), 28.XII.1937, T. Holden col.; Mazzaruni-Potaro: Cuyuni River , AMNH 73005, 1(155.6), 18.VIII.1983, Schmidt col.; AMNH 72961, 2(123.6-127.4), 12.VIII.1983, Schmidt col.; AMNH 72063, 1(97.7), 06.VIII.1982, Schmidt col.; Venezuela: Bolivar: Cuyuni River , ANSP 167919, 1(38.6), 23.I.1991, S. Schaefer col.; Brazil: Amazonas: Rio Uatumã, INPA 10433, 1(192.0), 17.IV.1983, Equipe de Ictiologia INPA col.; INPA 2724, 1(266.0), IX.1985, M. Jegu col.; INPA 2725, 2(225.0-245.0), VII.1985, M. Jegu col.; INPA 12918, 2(187.1-215.2), 31.I.1985, Equipe de Ictiologia INPA col.; Rio Pitinga, Cachoeira Quarenta Ilhas , INPA 3302, 1(278.0), 12.X.1989, F. Martinho col.; Pará: Rio Trombetas , INPA 3293, 1(198.0), 17.IV.1985, E. Ferreira col.; INPA 10425, 1(166.0), V.1988, Equipe de Ictiologia INPA col.; INPA 10420, 3(98.1-117.5), 1 Cleared and Stained, 10.XI.1981, Equipe de Ictiologia INPA col.; Rio Trombetas , Cachoeira Porteira, INPA 10418, 1(132.1), V.1988, Equipe de Ictiologia INPA col.; INPA 10425, 1(166.0), V.1988, Equipe de Ictiologia do INPA col.; Rio Trombetas , Cachoeira Vira-Mundo, INPA 3263, 1(139.3), 09.X.1985, Equipe de Ictiologia INPA col.; Rio Fresco , São Félix do Xingu , MZUSP 35995, 1(275.5), VIII.1983, M. Petrere col.; Rio Tocantins, INPA 10415, 2(97.0-110.6), 10.XI.1981, Equipe de Ictiologia INPA col.; INPA 10429, 1(217.0), 08.XI.1981, Equipe de Ictiologia INPA col.; INPA 10414, (102.2-114.6), I.1981, Equipe de Ictiologia INPA col.; INPA 10436, 1(200.6), XI.1980, Equipe de Ictiologia INPA col.; MZUSP 14673, 1(83.7), 17.IX.1970, Expedição Permanente à Amazônia col. Rondônia: Rio Machado , INPA 12916, 1(222.7), 04.VI.1984, G. Mendes col.

DESCRIPTION

Morphometric and meristic data are presented in Table I. Body relatively elongate, sub-cylindrical; greatest body depth at origin of dorsal fin. Dorsal profile of body convex. Ventral profile flattened from prepelvic region to anal fin. Ventral profile of caudal peduncle slightly convex.

Head pointed in profile. Mouth inferior and small (4.2-6.9 in HD). Lower jaw not extending beyond vertical through anterior edge of eye. Teeth small, villiform, and in single bands in both jaws. Snout pointed, typically longer than horizontal diameter of eye; nostrils of each side close together, anterior circular and posterior crescent-shaped.

Eye elliptical, horizontal diameter longer than vertical, 3.0- 3.6 in head length. Laterosensory canal segments clearly visible externally, passing through lachrymals, suborbitals, preopercle, and lower jaw. Preopercle margin slightly serrate. Gill rakers short and slender.

Scales ctenoid, except on snout and preopercle, where they are cycloid. Lateral line curved until the anterior third of second dorsal fin, extending to the hind margin of the caudal fin. Small ctenoid scales on proximal 2/3 of dorsal fin, proximal 3/4 of pelvic fin, proximal 3/4 of caudal fin, and proximal 1/2 of pectoral and anal fins.

First dorsal fin with 10 spines, first very small; a notch present between first and second dorsal fins; second dorsal with an spine. Posterior tip of pectoralfin not reaching the posterior tip of pelvic-fin when depressed. Anal-fin spine slender, most commonly 3.3-3.6 times in head length. Caudal fin rhombic in lateral view.

Swimbladder carrot-shaped with an anterior pair of short branched appendages, its posterior end slightly surpassing anus (fig. 3 a).

Color in alcohol: Head and dorsal 3/4 of body light tan, with small brown irregular spots, concentrated anteriorly. Lower 1/4 of body silvery. First dorsal fin light tan with dark edges and second dorsal fin with numerous small brown spots forming irregular stripes. Pectoral, pelvic, anal, and caudal fins light yellow, slightly silvery. Juveniles are light tan with brown spots smaller than eye on body.

Distribution: Known from rivers of the Amazon River basin in Brazil, and Cuyuni and Essequibo River basins in Guyana (fig. 4).

REMARKS

In the description of Corvina grunniens , a South American freshwater sciaenid from the Essequibo River, Guyana, Schomburgk (1843: 136) cited the presence of black dorsal and anal fins spots, elongate eye, terminal mouth, 32 dorsal-fin soft rays, 14 pectoral-fin rays, and anal-fin with one spine and 7 soft rays. Eigenmann (1912: 476-78), in his study of the freshwater fishes of Guyana, based on four specimens, also reported the presence of a single anal spine in a sciaenid species, identified by him as Pachypops grunniens .

The comparision of swimbladder and external morphology of Petilipinnis to the South American freshwater genera, Pachypops , Pachyurus , and Plagioscion , is presented in Table 2 .

The single published phylogenetic hypothesis about sciaenid genera relationships was proposed by Sazaki (1989). In his work, Pachyurus and Pachypops , both included in the subfamily Pachyurinae , comprise a monophyletic clade supported by three synapomorphies: an anteriorly straight vomer, a pointed ventral tip of the nasal bone, and the dorsal surface of the third infraorbital lying almost parallel to the horizontal axis of eye. A fourth synapomorphy pointed out by Sazaki (1989: 40), a suspensorium strongly depressed, is here discarded as a character since the depression level is not comparable among other genera within the family. The sinapomorfies of the Pachyurinae shared by Petilipinnis reinforces its position in this subfamily. Petilipinnis also shares with Pachyurus the derived second pharyngobranchial plate enlarged, more than twice as large as that on the third epibranquial; in Pachypops the plate on the second pharyngobranchial is smaller than that on the third epibranquial ( Sazaki, 1989: 56; Casatti, 2000: 29). Another derived Pachyurus character is a derived metapterygoid lateral margin overlapping the medial side of the lower arm of hyomandibular which, in contrast, is not found in Petilipinnis and Pachypops that present a straight metapterygoid lateral margin ( Sazaki, 1989: 40; Casatti, 2000: 31).

COMPARATIVE MATERIAL

Cleared and stained specimens: Pachypops fourcroi, MZUSP 34096, 1 specimen, Rio Trombetas, Cuminá, PA, 96,4 mm; MZUSP 34113, 1 specimen, Rio Tapajós, Alter do Chão , PA, 86,7 mm; Pachypops sp. , MZUSP 34108, 1 specimen, Rio Machado , Jamarizinho, RO, 42,7 mm; Pachypops trifilis, MZUSP 6754, 1 specimen, Rio Negro, Manaus, AM, 101,1 mm; Pachyurus adspersus , uncatalogued, 2 specimens, Rio Mucuri , BA, 118,7-118,7 mm; Pachyurus bonariensis, MCP 13206, 2 specimens, Rio Ijuí , RS, 119,9-127,1 mm; Pachyurus francisci, MZUSP 39757, 1 specimen, Rio São Francisco , Projeto UHE/ Formoso, MG, 164,1 mm; Pachyurus paucirastrus, MNRJ 13240, 1 specimen, Rio Tocantins, Cavalcante, GO, 118,4 mm; Pachyurus schomburgkii, INPA 11993, 1 specimen, Rio Uatumã , AM, 186,6 mm; Pachyurus sp. , INPA 15050, 1 specimen, Rio Xingu , Senador José Porfírio, PA, 150,3 mm; Pachyurus sp. , MZUSP 49721, 1 specimen, Rio Purus , AM, 84,4 mm; Pachyurus squamipinnis , uncatalogued, 2 specimens, Rio São Francisco , Projeto UHE/ Formoso, MG, 130,0-160,0 mm.

Figures

Figure 1. Petilipinnis grunniens, MZUSP 35995, 276.0 mm from Rio Fresco, state of Pará, Brazil.

Figure 2. Petilipinnis grunniens, juvenile, ANSP 176038, 33.9 mm from Essequibo River, Guyana.