Carlos Alberto S. de Lucena

Laboratório de Ictiologia, Museu de Ciências e Tecnologia da PUCRS. Av. Ipiranga 6681, 90619-900, Porto Alegre, RS, Brazil; lucena@pucrs.br

Dirección de correspondencia

Abstract

A freshwater fish Roeboides loftini n.sp. is described from the Río Coclé del Norte drainage of the Atlantic versant of Panamá. The new species differs from other species of the Roeboides guatemalensis-group by the number of perforated scales on the lateral line (83-100), body depth (31.8-36.1%), predorsal distance (49.1-51.9%) and the shape of the humeral spot. Rev. Biol. Trop. 59 (4): 1663-1667. Epub 2011 December 01.

Key words: distribution, freshwater fish, Río Coclé del Norte, Atlantic versant.

Palabras clave: distribución, peces de agua dulce, Río Coclé del Norte, vertiente del Atlántico.

The genus Roeboides Günther, 1864 comprises a monophyletic assemblage of 16 valid species occurring in Central and South America. Six Central American species (R. dayi Steindachner, 1878, R. guatemalensis Günther, 1864, R. occidentalis Meek & Hildebrand, 1916, R. bouchellei Fowler, 1923, R. ilsea Bussing, 1985, & R. carti (Lucena 2000) along with R. dientonito Schultz, 1944 from Lago Maracaibo, the Río Orinoco drainage and rivers of Northwestern Guyana, compose the R. guatemalensis-group (Lucena 2007).

Among the synapomorphies that support the Roeboides guatemalensis-group are: the presence of infraorbitals 4 and 5, the presence of cusps on the teeth of the inner tooth series of the premaxilla; the absence of D4 teeth of the dentary (Lucena 1998); a long, slender projection on the lower posterior margin of cleithrum slightly surpassing the first pectoral-fin ray, and a humeral spot located posterior to the vertical through the middle of the pectoral fin (Lucena submitted).

Lucena (2000) examined a few young specimens in poor condition from the Río Coclé del Norte drainage (Río Tambo) and identified them as Roeboides sp. He pointed out some differences between these specimens and specimens belonging to other species of Roeboides in Central America. The analysis of new samples from that drainage allowed the recognition of a new species of Roeboides, which is described herein.

Holotype: STRI-7655 (65.1mm SL), Río Turbe, tributary of Río San Juan, upper Río Coclé del Norte drainage, Panamá, 08º 47’05’’ N - 80º 38’10’’ W, 2009, Jorge Garcia.

Paratypes: STRI-7656 (3, 44.4-64.6mm SL), same locality as holotype; STRI-7657 (14, 39.7-80.2mm SL, 1 c&s specimen, 65.0mm SL), Río Turbe, tributary of Río San Juan, upper Río Coclé del Norte drainage, Panamá. 08º47’09’’ N - 80º 37’55’’ W, MCP 45775 (3, 57.7-75.1mm SL), same locality as STRI-7657.

Diagnosis: Roeboides loftini is a member of the R. guatemalensis-group. It differs from R. occidentalis, R. dayi, and R. dientonito by the number of lateral line scales (83-100 vs. 51-80), from R. dayi and R. dientonito by the number of scale rows above the lateral line (20-22 vs. 10-18) and around the caudal peduncle (27-30 vs. 17-24), and from R. dientonito by the number of scale rows below the lateral line (20-24 vs. 17-21). Roeboides loftini differs from R. ilsea, a species with a high number of lateral line scales (84-93), by the lower body depth (31.8-36.1%, mean=33.7% vs. 36.9-41.8%, mean=38.8%) and shorter predorsal distance (49.1-51.9%, mean=50.4% vs. 51.4-55.9%, mean=52.9%). Roeboides loftini differs from other Central American species, R. bouchellei, R. guatemalensis and R. carti in the shape of the humeral spot. Roeboides bouchellei exhibits a small, sometimes inconspicuous, slightly vertically elongate humeral spot, extending over 3 or 4 horizontal rows of scales and 2 or 3 vertical rows, whereas R. loftini exhibits a conspicuous, slightly rounded humeral spot extending over 5-7 horizontal rows of scales and 5-8 vertical rows. In addition, R. loftini has a tenuous, short extension on the anterodorsal portion of the humeral spot (Fig. 1) which is absent in R. bouchellei. The humeral spot of R. carti reaches or surpasses the vertical through the origin of the anal fin and, in adults, extends posteriorly to the vertical through the origin of the dorsal fin (Lucena 2000). Roeboides guatemalensis has a large, anteriorly sometimes bifurcate, black stripe, extending between the vertical through the middle of the pelvic fin and the vertical near the posterior terminus of the base of the dorsal fin (Lucena 2000). Roeboides loftini differs from R. carti and R. guatemalensis by its rounded humeral spot located far from the verticals through the origins of the dorsal and anal fins (5-8 and 3-5 vertical series of scales, respectively).

Description: Table 1 presents the morphometric data for the holotype and 20 paratypes. Predorsal profile elevated and convex from base of supraoccipital process to dorsal fin origin; posteroventrally sloped along dorsal-fin base and straight from terminus of dorsal fin base to caudal peduncle. Ventral profile convex from lower lip to anal fin origin; straight along anal fin base. Mouth subterminal with lower jaw slightly shorter than upper jaw. Snout profile convex from dorsal view. Maxilla expanded anteroposteriorly, extending posteriorly to vertical through middle of orbit or slightly beyond that point. Premaxilla with two large mamilliform teeth projecting anteriorly from each side of upper jaw at margin of lip. Rows of teeth irregular. Outer row with 4 to 6 conical teeth, rarely with side cusps. Inner row with 3 to 5 mamilliform-like teeth with two small lateral cusps. Maxilla with 9-14 teeth; first five to seven conic with one or two mamilliform teeth displaced towards lateral surface of bone and followed by conic or mamilliform-like teeth along ventral border of bone. Dentary with one large mamilliform teeth projecting anterolaterally and laterally (Lucena, 1998). Two anteriormost dentary tooth larger, mamilliform, weakly tricuspid and followed by two or three smaller conic and one mamilliform-like tricuspid teeth and then 9-14 smaller conic teeth posteriorly curved lingually.

Gill-rakers long, upper limb with five to seven rakers (n=20, mode=6) [6], lower limb with nine or ten rakers (n=20, mode=9) [9].

Dorsal fin rays i+9 (n=20). Fin origin situated approximately slightly beyond vertical through origin of anal fin. Anal fin rays iv-v, 45-50 (n=20, mode=47) [46]. Males with one or two small, retrorse bony hooks per segment on first to seventh or eighth segmented rays. Pectoral fin rays i+12-14 (n=19, mode=13) [12]. Tip of longest ray falling slightly short of, or reaching, anal fin origin. Pelvic fin rays i,7 (n=20). Longest pelvic ray extending beyond anal fin origin. Males with one bony hook per segment present from first to seventh segmented anal fin rays. Caudal fin forked with 19 principal rays (n=20).

Lateral line scales 83-100 (n=20, mode=88/89) [85]. Scale rows above lateral line 20-22 (n=20, mode=20) [21]; scale rows below lateral line 20-24 (n=19, mode=22) [22]; scale rows around caudal peduncle 25-30 (n=10, mode=29/30) [20]. Precaudal vertebrae 15; caudal vetrabrae 23; total vertebrae 38 (n=1 c&s specimen).

Color in alcohol: Ground color yellowishtan. Dorsal portions of head and body densely pigmented dark brown. Conspicuous dark lateral band extending between margin of opercle and caudal fin base. Expanded posteriorly into large spot on caudal peduncle. Slightly dusky lateral band situated anterior of humeral spot. Most specimens with chromatophores concentrated along the myosepta within lateral band resulting in chevron-shaped marks. Conspicuous black humeral spot distinctly separated from verticals through origins of dorsal and anal fins by 5-8 and 3-5 rows of scales, respectively. Humeral spot in well-preserved specimens shows faint dorsal, anteriorly-oriented extension. Fins, especially dorsal and anal fins, dusky.

Color in life: Overall coloration silvery or yellowish. Tip of snout black. Dark midlateral stripe sometimes inconspicuous and hidden by silvery lateral band. Dark humeral spot conspicuous. Caudal peduncle spot dark diffuse. Caudal fin yellow. Tip of caudal-fin rays clear. Other fins slightly yellowish.

Etymology: The specific epithet, loftini, is a patronym in honor of Dr. Horace Loftin in recognition of his contributions to our knowledge of the distribution of the freshwater fishes of Panamá.

Roeboides loftini has an incomplete infraorbital series. One of the synapomorphies of the R. guatemalensis-group is a complete infraorbital series with the presence of the fourth and fifth infraorbitals (Lucena submitted). The condition present in R. loftini may be parsimoniously considered an autapomorphy.

In addition to R. loftini, five species of Roeboides occur in Panamá, all showing disjunct distributions: R. dayi, R. guatemalensis, and R. carti from the Atlantic versant, and R. occidentalis and R. bouchellei, from the Pacific versant. Along the Atlantic versant of Panamá, the Río Coclé del Norte drainage represents the westernmost occurrence of Roeboides. R. bouchellei, another species that may occur in the Atlantic drainages of Central America, has its distribution from Río Matina, Costa Rica (Bussing 2002) to the Río Negro drainage (or Río Sico Tinto), Honduras (Matamoros et al. 2009). This apparent gap in the Atlantic versant distribution of Panamá may be due to the lack of collections in that area. Roeboides is absent along the Atlantic coast of Central America North from Río Negro, Honduras.