Pachypops trifilis ( Mueller and Troschel 1848)

Lilian Casatti, 2002, Taxonomy of the South American genus Pachypops Gill 1861 (Teleostei: Perciformes: Sciaenidae), with the description of a new species., Zootaxa 26, pp. 1-20 : 10-14

Pachypops trifilis ( Mueller and Troschel 1848)

(Fig. 5)

Micropogon trifilis Mueller and Troschel 1848 : 622 (type locality: Guyana).

Pachypops trifilis : Gill 1861: 87 (comparison with Corvina furcraea Cuvier ), Steindachner 1863: 168 (redescription, Rio Guaporé and Rio Negro), Steindachner 1879: 12 (junior synonym of Pachyurus trifilis ), Jordan and Eigenmann 1889: 413 (review of American Sciaenidae, as valid), Eigenmann and Eigenmann 1891: 67 (listed, Rio Guaporé and Guyana), Eigenmann 1910: 468 (listed, rio Guaporé and Guyana), Eigenmann 1912: 72 (listed, Demerara River), Campos 1942: 18 (revision), Fowler 1954: 252 (freshwater fishes of Brazil, erroneously listed as synonym of Pachypops camposi ), Travassos and Rego-Barros 1971: 60 (listed, Brazil), Chao 1978: 42 (west Atlantic Sciaenidae), Cervigón 1982: 238 (comparison with P. cevegei ), Aguilera 1983: 116 (soft anatomy), Aguilera 1987: 91 (soft anatomy), Ferreira et al. 1998: 146 (key, commercial fishes of Santarém, Brazil).

Pachyurus trifilis : Steindachner 1879: 12 ( new combination for Pachypops trifilis ( Mueller and Troschel) ).

Pachypops camposi Fowler 1954 : 252, fig. 843 (type locality: Rupununi River, Guyana), Cervigón 1982: 238 (reference).

Material examined. Type specimens. - ZMB 936, holotype of Micropogon trifilis (150.0 mm SL), Guyana, no locality information. - ANSP 39773, holotype of Pachypops camposi (148.0 mm SL), Rupununi River, Guyana.

Non-type (40 specimens). - Bolivia: Río Mamoré, MNHN 1988-1959 (1, 125.6) ; - Brazil: Amazonas: Rio Negro, between rio Tarumã and Tarumã-Mirim, INPA 8503 (2, 87.1- 89.9) ; Igarapé Jaraqui, tributary of Rio Negro, MZUSP 6226 (1, 128.3) ; Rio Negro, Anavilhanas, INPA 618 (2[4], 81.7-89.3) , INPA 610 (1, 163.0) ; Rio Negro, Lago do Prato, INPA 12364 (1, 96.3) ; Rio Negro, NMW 85487 (2, 144.2-157.0) , MZUSP 6754 (2[5], 94.9-136.7, 1 C & S) ; Lago Januari, MZUSP 6909 (2, 121.7-136.2) ; Lago Tefé, INPA 12921 (2, 135.1-151.0) ; Rio Tefé, Lago Tefé, INPA 626 (2, 96.4-105.3) ; Rio Purus, Lago Jari, INPA 603 (10[12], 140.8-189.4) ; Rio Coari, Lago Coari, INPA 8270 (2[3], 71.9- 90.8) ; Rio Coari, INPA 11982 (2[4], 113.2-119.9) ; Rio Japurá, MPEG 1672 (3[9], 112.0- 124.6) ; Rio Uatumã, INPA 10431 (1, 135.5) ; Pará State: Lago Grande de Monte Alegre, INPA 10171 (2, 146.4-152.0) ; Lago Aruanã, MPEG 1668 (2[3], 132.2-149.5) ; Rio Trombetas, Oriximiná, MZUSP 5487 (2[3], 133.7-151.8) .

Diagnosis. A species of Pachypops distinguished by the following combination of characters: presence of three or four longitudinal dark stripes on trunk (versus trunk without stripes), and horizontal diameter of eye 3.0-3.6 in HL (versus 2.4-3.1 in P. fourcroi , and 2.2-2.8 in P. pigmaeus ).

Description. Morphometrics and meristics presented in Table 2. Body elongate, dorsal profile moderately arched, ventral profile nearly straight from prepelvic region to anal fin origin. Maximum body depth at origin of dorsal fin. Head pointed; mouth inferior and small. Maxillar not extending beyond vertical line through anterior edge of eye. Underside of lower jaw with three pairs of mental pores and three mental barbels. Teeth uniformly small, villiform, set in bands on both jaws.

Snout longer than horizontal diameter of eye, with 10 small pores; nostrils closely set, anterior circular and posterior crescent-shaped. Eye elliptical, horizontal diameter longer than vertical height. Laterosensory canal segments in infraorbitals, preopercle, and lower jaw visible externally. Preopercle margin slightly serrate. Gill rakers short and slender; 18- 22 (usually 19) rakers in first gill arch.

Scales usually ctenoid (cycloid on lachrymal, snout, and preopercle). Anterior half of lateral line curved, posterior half extending straight to posterior margin of caudal fin; 48- 52 (usually 50) pored lateral-line scales from supracleithrum to hypural joint; 6-8 [7] (usually6) scale rows above lateral line; 7-10 (usually 8) scale rows below lateral line. Bases of second dorsal, pelvic, pectoral, and anal fins with 3 or 4 rows of small scales. Caudal fin almost completely covered by scales. Dorsal fins: X, I + 24-29 (usually 26), first spine very small (less than 1/5 of the second one); notch present between first and second dorsal fins. Pectoral-fin: I + 15-17 (usually 16), falcate, its posterior tip reaches nearly to vertical through posterior tip of pelvic fin. Pelvic-fin: I + 5, first soft ray prolonged as filament, its tip usually reaches nearly to anus. Anal-fin: II + 6, first spine reduced, approximately equal in length to first dorsal spine; second spine rigid and long, almost as long as longest soft ray. Caudal-fin rhomboidal with 17 principal rays (9+8).

Swimbladder carrot-shaped with pair of short appendages anteriorly, from which a shorter paired appendages project posteriorly (Fig. 1a); posterior tip of appendages reach nearly to anus.

Color in alcohol. Coloration of head and dorsal half of trunk light tan. Some individuals with dorsal surface darkly pigmented, from snout to first dorsal-fin. Trunk with three (sometimes four) longitudinal dark stripes extending from pectoral-fin base to caudal-fin base (few specimens without evident stripes), contrasting with the clear ground color of body. Some individuals also with a wider clear stripe above and/or below principal stripe. Ventral portion of body light tan. First dorsal fin light tan with margin outlined by small chromatophores; second dorsal fin with dark chromatophores forming two dusky longitudinal stripes. Pectoral, pelvic, anal, and caudal fins light tan, sometimes with irregular concentrations of dark chromatophores.

Distribution. Rivers of Guyana and Rio Amazonas basin, in Bolivia and Brazil (Fig. 6).

Comments. The holotype of Micropogon trifilis is deposited in the Museum für Naturkunde Humboldt-Universität ( ZMB 936), and was examined and photographed by Hans-J. Paepke. Although distinctive stripes are no longer visible in the holotype, the proportion between head length and horizontal eye diameter readily indicates that it is a specimen of the striped species, and not of P. fourcroi , as suggested by Eigenmann (1912: 474). Visible stripes were also lacking in many other preserved specimens of P. trifilis .

In the original description of Pachypops camposi from the Rupununi River, Guyana, Fowler (1954: 252) pointed out that the coloration is the most important feature discriminating that species from the remaining species of the genus, and, in agreement with Steindachner (1863: 168), considered the striped species to be a different form from that described by Müller and Troschel. On the other hand, given the horizontal eye diameter (the most distinctive character to diagnose P. trifilis ) Micropogon trifilis and Pachypops camposi are aparently conspecific. Therefore, by priority (ICZN 1999), the senior synonym is Micropogon trifilis and the appropriate combination is Pachypops trifilis .

Pearson (1937: 112) listed P. trifilis for the Paraguay River basin, an obvious misidentification, because this species is unknown from that basin.