Paracetopsis esmeraldas, Vari & Ferraris Jr & de Pinna, 2005

Vari, Richard P., Ferraris Jr, Carl J. & de Pinna, Mário C. C., 2005, The Neotropical whale catfishes (Siluriformes: Cetopsidae: Cetopsinae), a revisionary study, Neotropical Ichthyology 3 (2), pp. 127-238 : 228-231

Paracetopsis esmeraldas , new species

Figs. 55 , 57 , Tables 23-29

Pseudocetopsis amphiloxa [not of Eigenmann].– Barriga, 1994b: 77, 80, 84 [ Ecuador, río Esmeraldas; common name; habitat; not citation from Ecuador: río Mira, río Mataje, or río Santiago].

Diagnosis. Paracetopsis esmeraldas is distinguished from all other species in the Cetopsinae with the exception of P. bleekeri and P. atahualpa by the combination of the possession of a vomerine tooth patch with more than one row of teeth and a medial separation of the contralateral components of the patch. Paracetopsis esmeraldas differs from P. atahualpa and P. bleekeri to a notable degree in the number of total vertebrae (50 to 53, with 22 of 26 radiographed specimens having 51 to 53, vertebrae versus 50 in P. atahualpa , and 47 to 50, with 50 in only 1 of 21 radiographed specimens in P. bleekeri ). Paracetopsis esmeraldas further differs from P. atahualpa in the dorsal profile of the body at the rear of the head in the area of contact of the externally apparent posterodorsal portion of the jaw musculature and the anterior portion of the epaxial musculature (without distinct notch versus with distinct notch, respectively), the degree of pigmentation of the basal portion of the maxillary barbel (pale or with few scattered, dark chromatophores versus distinctly dark, respectively), and to a degree in the number of caudal vertebrae (37 to 40, with 38 most common, versus 36 to 38, with 37 most common, respectively; see Table 28). Paracetopsis esmeraldas further differs from P. bleekeri in the extent of the medial gap in the vomerine tooth patch (separated by a limited gap between the contralateral components of the tooth patch equivalent to the width of one or two vomerine teeth versus separated by a distance equivalent to the width of three or four vomerine teeth, respectively), in the pigmentation on the lateral surface of the opercle (patch of dark pigmentation present versus absent, respectively), and in the mode and to a degree in the range of the number of caudal vertebrae (37 to 40, with 38 most common, in P. esmeraldas versus 34 to 38, with 36 most common, in P. bleekeri , see Table 28).

Description. Body relatively elongate, slightly-compressed laterally anteriorly and becoming distinctly-compressed posteriorly. Body depth at dorsal-fin origin approximately 0.22- 0.24 of SL, and approximately equal to distance from anterior margin of orbit to posterior margin of opercle. Lateral line on body complete, unbranched, and midlateral; extending from vertical through pectoral-fin base to hypural plate with short, dorsal bend on hypural plate. Single available, large individual not demonstrating few, short, ventrally-directed branches of lateral line occurring in comparably-sized individuals of con- generic species. Dorsal profile of body slightly convex from nape to dorsal-fin origin, straight from dorsal-fin origin to caudal-fin base. Ventral profile of body convex along abdomen, approximately straight, but posterodorsally-slanted along base of anal fin. Caudal-peduncle depth approximately equal to caudal-peduncle length.

Head in profile acutely triangular with bluntly-rounded snout. Dorsal profile of head convex from tip of snout to vertical through posterior nostril and nearly straight from that point to nape. Ventral profile of head nearly straight and slightly oblique. Profile of snout in dorsal view broadly rounded in smaller specimens, more triangular in largest examined individual. Postorbital margins of head running nearly in parallel from dorsal view. Enlarged jaw musculature not evident externally on dorsal surface of postorbital portion of head. No notch in dorsal profile obvious in lateral view between posterodorsal margin of externally obvious jaw musculature and anterior margin of epaxial musculature.

Opercular membrane attaching to isthmus only in region anterior to vertical through pectoral-fin insertion. Opercular opening large; extending ventral of pectoral-fin insertion by distance equal to that from tip of snout to posterior margin of orbit and extending dorsal of pectoral-fin insertion by distance equal to snout length.

Eye situated on lateral surface of head; located entirely dorsal to horizontal extending through pectoral-fin insertion; eye visible in dorsal view, but not in ventral view of head. Middle of orbit at approximately anterior one-fifth of HL in most specimens (55-145 mm SL), but at approximately anterior one-fourth of HL in largest examined specimen (188 mm SL). Eye diameter approximately equal to one-half of snout length. Interorbital width approximately equal to distance from tip of snout to posterior margin of orbit. Anterior narial opening circular, surrounded by short, anteriorly-directed, tubular rim of skin. Opening of anterior nares located ventral of horizontal through tip of snout and at horizontal extending through maxillary-barbel origin. Distance between anterior nares approximately equal to distance from tip of snout to middle of eye. Posterior narial opening located on dorsal surface of head and along vertical through anterior margin of orbit; opening of posterior nares nearly round and almost completely surrounded by flap of skin, with anterior portion of flap highest and narrow gap between margins of flap posteriorly.

Mouth inferior; its width approximately one-half of HL. Margin of lower jaw gently rounded, its posterior limit reaching to vertical through posterior margin of orbit. Premaxillary tooth patch in form of gently-arched band continuous across midline, with anterior margin convex and posterior margin concave and running in parallel to anterior margin. Teeth on premaxilla small, conical, sharply-pointed, and arranged in four, regular rows in most examined specimens (55-145 mm SL), but with five regular rows present in largest examined individual (188 mm SL). Vomerine teeth arranged in distinct, contralateral patches located to each side of midline, with patches obliquely-aligned and slightly separated medially by distance equivalent to width of one or two vomerine teeth. Vomerine teeth similar in form to, but distinctly larger than, those on premaxilla, with one row medially and second shorter row laterally in smaller specimens and with two complete rows medially and third shorter row laterally in larger individuals. Dentary teeth comparable in size and shape to premaxillary teeth. Dentary dentition consisting of four rows medially, that taper to two rows laterally.

Maxillary barbel slender, its length approximately equal to distance from tip of snout to middle of eye in most specimens (45-145 mm SL), approximately equal to snout length in single distinctly larger specimen (188 mm SL); barbel origin located ventral to middle of orbit. Mental barbels approximately equal in length to maxillary barbel and to each other. Medial mentalbarbel origin located along vertical through rictus of jaw. Lateral mental-barbel origin situated only slightly posterior to medial mental-barbel origin. Tips of adpressed mental barbels falling short of posterior margin of opercle.

Dorsal fin moderately large overall with length of dorsalfin base approximately 0.38-0.41 of HL. Longest dorsal-fin ray equal in length to approximately three-fourths of HL in most examined specimens (45-145 mm SL), approximately two-thirds of HL in single, distinctly larger examined individual (188 mm SL). Dorsal-fin spinelet absent. First dorsal-fin ray not spinous and without distal filament (see “Sexual Dimorphism” below). Distal margin of dorsal fin straight, with first ray longest. Dorsal-fin origin located at, or slightly short of, approximately anterior one-third of SL and along vertical extending through distal one-fourth of adpressed pectoral fin. Tip of adpressed dorsal fin falling slightly short of vertical through tip of adpressed pelvic fin but reaching vertical through anal-fin origin. Posterior most dorsal-fin ray without posterior, membranous attachment to body.

Caudal fin moderately-forked, symmetrical; tips of lobes slightly rounded. Length of longest caudal-fin ray approximately two times length of middle fin rays in most examined specimens, approximately 1.5 times length of middle fin rays in single distinctly larger specimen.

Base of anal fin comparatively long. Anal-fin origin located slightly to distinctly posterior of middle of SL. Anal-fin margin straight along entire length (see “Sexual Dimorphism” below) with posterior most unbranched fin ray longest and subsequent fin rays becoming progressively shorter. Posterior most anal-fin ray without posterior, membranous attachment to body.

Pelvic fin moderately long. Distal margin of pelvic fin nearly straight, with first branched ray longest. Pelvic-fin insertion located distinctly anterior to middle of SL and slightly posterior of vertical through posterior terminus of base of dorsal fin. Tip of adpressed pelvic fin extending beyond middle of SL; reaching slightly posterior of vent and nearly to anal-fin origin in specimens of smaller and moderate sizes, but reaching only to middle of vent in single, distinctly larger examined individual. Medial most pelvic-fin ray with membranous attachment to body for basal two-thirds of its length.

Pectoral-fin length approximately two-thirds of HL. Pectoral-fin margin very slightly concave laterally and then convex medially, with first ray longest. First pectoral-fin ray not spinous and without short, distal filament (see “Sexual Dimorphism” below).

Coloration in alcohol. Head and body with scattered, dark pigmentation dorsally and laterally, with overall coloration somewhat darker dorsally. Abdomen and underside of head and snout lack dark pigmentation. Blotch of darker pigmentation located on body immediately posterior of opercle and dorsal to basal one-half of adpressed pectoral fin. Lateral surface of head with distinct boundary between dorsal pigmented and ventral unpigmented regions; boundary extending from level of maxillary barbel posteriorly to base of operculum; boundary distinct in specimens of 55 to 145 mm SL, but obscured in single, distinctly larger examined specimen (188 mm SL). Lateral surface of opercle with variably distinct, dark blotch. Blotch more obvious in smaller specimens and located entirely dorsal of horizontal extending through pectoral-fin insertion (blotch not readily apparent in photograph of specimen, Fig. 56 ); blotch obscure in single, examined individual of distinctly larger body size. Posterior margin of opercle only lightly pigmented.

Dorsal fin covered with scattered, dark pigmentation; pigmentation slightly darker basally but not forming more intensely-pigmented region. Anal fin with scattered, poorlydeveloped, dark pigmentation on basal two-thirds and with margin of fin clear in specimens of smaller to moderate size, but fin pale overall in single, distinctly larger examined individual. Caudal fin dusky throughout. Pectoral fin with scattered, dark pigmentation on basal one-half of dorsal surface but lacking dark pigmentation on ventral surface. Pelvic fin with few, widely-scattered spots of dark pigmentation basally.

Maxillary barbel with scattered, dark pigmentation basally. Mental barbels without dark pigmentation.

Sexual dimorphism. Apparently none of the available specimens of Paracetopsis esmeraldas is a sexually mature male. This limitation renders it impossible to determine whether this species demonstrates the sexual dimorphism in the anal, pectoral, and dorsal fins that is present in the other species of Paracetopsis and many other species of the Cetopsinae .

Remarks. Barriga (1994b: 80) reported Pseudocetopsis amphiloxa from the río Esmeraldas, río Santiago, río Mataje, and río Mira of the Pacific Ocean versant of northwestern Ecuador. All examined samples of the Cetopsinae from the río Esmeraldas system are Paracetopsis esmeraldas and we consequently consider reports of the occurrence of Pseudocetopsis amphiloxa from that river basin to be based on material of Paracetopsis esmeraldas . In contrast, the examined samples of the Cetopsinae from the río Santiago that presumably were, at least in part, the basis for the citation of Pseudocetopsis amphiloxa by Barriga (1994b) are the Cetopsis amphiloxa of this study (see listing of specimens under “Material examined” for C. amphiloxa ). Paracetopsis esmeraldas does, however, occur in that river basin as evidenced by one examined specimen (CAS 162438) that originated in the río Santiago system. Although we have not examined the samples of the Cetopsinae from the río Mataje and río Mira that were identified by Barriga (1994b: 80) as C. amphiloxa , both of those river systems lie within the known range of that species, but beyond the limits of the known distribution of Paracetopsis esmeraldas . We tentatively conclude that the members of the Cetopsinae present in the río Mataje and río Mira systems are C. amphiloxa rather than Paracetopsis esmeraldas .

Distribution. Paracetopsis esmeraldas occurs in the Pacific Ocean versant rivers of northwestern Ecuador ( Fig. 55 ).

Etymology. The species name, esmeraldas , is in reference to both the Ecuadorian Province of Esmeraldas from which all specimens of the species originated and to the río Esmeraldas basin within which the type series of the species was collected.

Common Name. Ecuador: “Ciego” ( Barriga, 1994b: 77).

Ecology. Barriga (1994b: 80) reported that Paracetopsis esmeraldas (cited therein as Pseudocetopsis amphiloxa ) is a freshwater species common to varying degrees within the río Esmeraldas basin.

with for Total Vertebrae

47484950515253

P. atahualpa 5

P. bleekeri 2 5 13 1

P. esmeraldas 4 12 9 1 Material examined. 32 specimens (55-188 mm SL). Holotype. Ecuador. Esmeraldas: río Blanco, 4 km above junction with río Quininde (0°20’N, 79°28’W; río Esmeraldas basin), collected 20 October 1971, MCZ 48768, 1 (68) . Paratypes. 31 specimens (55- 188 mm SL). Ecuador. Esmeraldas: río Blanco, 4 km above junction with río Quininde (0°20’N, 79°28’W; río Esmeraldas basin), collected with holotype, MCZ 162749 , 10 (49-90) ; USNM 372749 , 3 (61-72) , MEPN 1530 , 3 (62-81) . Río Esmeraldas, 35 km upstream of Esmeraldas (0°59’N, 79°42’W), 21 Oct 1971, MCZ 48769, 10 (68-88) ; MCZ 48770, 1 (145) ; MZUSP 22328 , 3 (2, 55-67; 1 specimen, 58 mm, cleared and stained) . Lower río Santiago or pools and marshes near village of Borbon (latter locality at 1°04’N, 78°59’W) at less than 10 m elevation, M. Olalla, August 1951, CAS 162438 , 1 (188).

Figures

Fig. 55. Map of northwestern South America showing geographic distribution of Paracetopsis atahualpa (1 = holotype locality), Paracetopsis bleekeri (2 = neotype locality; also holotype locality for Cetopsis occidentalis), and Paracetopsis esmeraldas (3 = holotype locality) (some symbols represent more that one locality and/or lot of specimens).

Fig. 57. Paracetopsis esmeraldas, new species, holotype, MCZ 48768, 68 mm SL; Ecuador, Esmeraldas, río Esmeraldas basin, río Blanco, 4 km above junction with río Quininde (0°20’N, 79°28’W).

Fig. 56. Paracetopsis bleekeri, ZMH 12211, 158 mm SL; Ecuador, Guayas, Guayaquil (2°10’S, 79°54’W).