Brachyhypopomus palenque, Crampton & de Santana & Waddell & Lovejoy, 2016

Crampton, William G. R., Santana, Carlos D. de, Waddell, Joseph C. & Lovejoy, Nathan R., 2016, A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species, Neotropical Ichthyology (e 150146) 14 (4), pp. 639-790 : 749-753

Brachyhypopomus palenque , new species urn:lsid:zoobank.org:act:BA8EFB5D-A00F-42A9-BB1C-F7750BCBDF79

( Fig. 37 ; Tables 2-5, 17)

Brachyhypopomus occidentalis . - Barriga, 1994: 84, note on diet ( NW Ecuador, catalog of fishes). - Jiménez-Prado et al., 2015: 283, color photograph ( Ecuador, Pacific drainages - Santiago- Cayapas , Esmeraldas, Guayas, Daule , Cóngoma , Güijas , and Baba ) .

Brachyhypopomus sp. M. - Crampton & Albert, 2006: 672, fig. 23.8, position in phylogenetic tree, 681; notes on EODs (gymnotiform species and EOD diversity).

Brachyhypopomus sp. ‘pal’/PAL. - Lovejoy et al., 2010: 281, table 1; 283, figs. 2-3 (outgroup in phylogenetic analysis of Gymnotus ). -Crampton, 2011: 176, table 10.2, species list; 179, figs. 10.2-10.3, phylogeny, geographical and ecological distributions (gymnotiform biology). - Carvalho, 2013: 181-185, figs. 41-43, position in phylogeny (phylogenetic systematics of Rhamphichthyoidea ). - Tagliacollo et al., 2016: 28, fig. 5 (phylogeny of Gymnotiformes ).

Brachyhypopomus sp. PALE. -Maldonado-Ocampo et al., 2014: 8, fig. 6, position in phylogeny (phylogeny of Rhamphichthyoidea ).

Brachyhypopomus sp. “palenque ”. - Crampton et al., 2016: 1-66, table 1, 3-4, figs. 1-7, 18-20 (phylogeny, biogeography and ecology of Brachyhypopomus ).

Holotype. UF 180270 , female, 149 mm TL, 135 mm LEA, Ecuador, Los Ríos, mun. Buena Fé, Parroquia Patricia Pilar, Centro Científico río Palenque , 45 km S Santo Domingo, small forest stream, affl. río Palenque , río Guayas dr., 00°35′01″S, 079°22′13″W, 16 Apr 2004, W. Crampton, J. Albert, F. Villao, R. Navarrete.

Paratypes. 31 specimens. Ecuador . Los Ríos. FMNH 79125, 3, 56-97 mm, FMNH 79126, 1, 84 mm, FMNH

79209, 1, 114 mm, FMNH 79210, 1, 97 mm, FMNH 79211, 1, 104 mm, FMNH 93123, 13, 62-196 mm, FMNH 93133, 7, 86-150 mm, FMNH 93142, 2, 77-83 mm, FMNH 93143, 2, 107-115 mm, Estación Biológica río Palenque, series of small pools at bottom of old rd. to station, and pools nr. the station, affl. río Palenque, affl. río Quevedo, affl. río Babahoyo, río Guayas dr., ca. 00°35′S, 079°22′W, 31 Jul 1974, G. Glodek, G. Whitmire & J. Dryan.

Non-types. 74 specimens. Ecuador. Azuay. ZOOA, FR-PE-003, 1, Ponce Enrique (Cantón), río Fermín , affl. río Siete , río Siete dr. ( Gulf of Guayaquil ), 03º03′26″S, 079º44′11″W . Cotopaxi. USNM 270692 , 5 (2 CS), 115-203 mm, “río Sigchos, affl. río Esmeraldo” [interpreted as río Toachi nr. town Sigchos, Cotopaxi, affl. río Esmeraldas], río Esmaraldas dr., no coordinates . Esmeraldas. SU 54426 , 2 , 142-150 mm, río Cupa confl. with río Blanco at the Guaillabamba junction, río Esmeraldas dr., ca. 00°27′N, 079°24′W . USNM 270695 , 2 , 99-116 mm, río Bogotá, río Santiago dr., ca. 01°02′N, 078°50′W . Guayas. UF 35330 , 1, 150 mm, 6.7 km S Nobol, río Daule , rio Guayas dr., ca. 01°58′S, 080°00′W . Los Ríos (localities from río Guayas dr.). ROM 93742, 1, 123 mm, Babahoyo (Cantón), Caracol (Sector), río Clara at La Clara, 01°40′30″S, 079°23′14″W . ROM 93755, 3, 145-181 mm, Montalvo (Cantón and Sector), creek on San José del Tambo-Juan Montalvo rd., 01°50′16″S, 079°16′14″W . UF 148572 , 4 (3 female, 143- 157 mm, 1 male, 203 mm), UF 180271 , 5 , immature (1 CS), 19-40 mm, collected with holotype. FMNH 79122, 9, 74- 110 mm, FMNH 79124, 9, 55-101 mm, Estación Biológica río Palenque, affl. río Palenque , affl. río Quevedo , affl. río Babahoyo , ca. 00°35′S, 079°22′W . Pichincha. CAS 72214, 3, 138-170 mm, río Toachi, affl. río Blanco, nr. Santo Domingo de los Colorados, río Esmeraldas dr., ca. 00°14′S, 079°03′W . KU 20008, 6, 76-119 mm, affl. río Baba at Hotel Zaracoyat, E edge Santo Domingo de los Colorados, affl. río Quevedo , río Babahoyo , río Guayas dr., ca. 00°15′S, 079°09′W . KU 20020, 1, 93 mm, rio Verde, 2 km SE Santo Domingo, río Baba, affl. río Quevedo , río Babahoyo , río Guayas dr., ca. 00°16′S, 079°09′W . ROM 93681, 6, 97-173 mm, San Miguel de los Bancos (Cantón), Puerto Quito (Sector), río Silanchi downstream of community of Silanchi, río Esmeraldas dr., 00°09′32″N, 079°14′36″W . ROM 93671, 4, 132-153 mm, San Miguel de los Bancos (Cantón), Puerto Quito (Sector), W Puerto Quito, río Blanco W Puerto Quito, río Esmeraldas dr., 00°07′12″N, 079°14′09″W . ROM 93707, 5, 128-160 mm, Santo Domingo de los Colorados (Cantón), Santo Domingo (Sector), río Chiguilpe nr. bridge, affl. río Quevedo , río Babahoyo , río Guayas dr., 00°19′21″S, 079°13′00″W . SU 54435 , 3 , 115-121 mm, río Toachi, affl. río Blanco , río Esmeraldas dr., ca. 00°06′S, 079°13′W . USNM 247230 , 1 , male, 168 mm, 5 km Santo Domingo de los Colorados, río Quinindé , affl. río Esmeraldas, río Esmeraldas dr., ca. 00°14′S, 079°13′W . USNM 270694 , 2 , 90-111 mm, río Mindó , río Esmeraldas dr., ca. 00°00′N, 078°49′W . Santo Domingo de los Tsáchilas. ZOOA WAM-14-05, 1, Santo Domingo (Cantón), Mimo Chico, nr. Santo Domingo, affl. río Blanco , affl. río Esmeraldas, río Esmeraldas dr., 00°13′26″S, 079°04′20″W .

Diagnosis. Brachyhypopomus palenque is diagnosed from congeners by the following combination of characters: caudal filament length 7.4-14.0% LEA, vs. 14.1-83.1% in B. alberti , B. batesi , B. benjamini , B. brevirostris , B. bullocki , B. cunia , B. draco , B. gauderio , B. hamiltoni , B. hendersoni , B. janeiroensis , B. jureiae , B. menezesi , B. pinnicaudatus , B. provenzanoi , B. sullivani , and B. walteri ; absence of pale stripe along middorsal region, vs. presence of prominent pale uninterrupted middorsal stripe from occipital region to base of caudal filament in B. arrayae , B. beebei , and B. belindae ; mouth width 25.1-37.8% HL, vs. 15.9-23.2% in B. bennetti and B. flavipomus ; absence of accessory electric organ over the opercular region, vs. presence in B. bombilla and B. regani ; precaudal vertebrae 19-22, vs. 24-26 in B. verdii ; absence of continuous or discontinuous dark vertical or diagonally oriented bars or saddles on body surface dorsal to lateral line, vs. presence in B. diazi and B. palenque .

Description. Head and body shape, and pigmentation illustrated in Fig. 37 . Meristic and morphometric data for examined specimens presented in Tables 2-5 and 17. Body shallow to moderate in depth. Head short to moderate in length and shallow to moderate in depth. Dorsal profile of head straight to slightly convex from occiput to snout, ventral profile of head approximately straight between operculum and snout, snout bulbous and rounded. Eye small to moderate in size. Upper jaw with slight sigmoidal angle between premaxillary and maxillary portions in lateral view. No accessory electric organ over operculum. Gill filaments on first gill arch 28-48 (median 38, n = 8). Pectoral fin broad, pectoral-fin rays 17-21 (no mode, median 18). Precaudal vertebrae 19-22 (mode 21), with 1-3 (mode 2) transitional vertebrae. Anal-fin origin slightly (<0.25 HL distance) to substantially (0.33-0.5 HL distance) posterior to tip of pectoral fin. Anal-fin rays 180-229 (median 206). Dorsal rami of recurrent branch of anterior lateral line nerve not visible. Middorsal region of body scaled. Rows of scales above lateral line 5-6 (mode 6). Lateral line continuous. Very sparse depigmented epidermal canals; as irregular short curved scratch-mark like grooves in mid dorsal flank in anterior half of body, and sporadically as short scratch marks close to and parallel to lateral line along much of body, but no dense crisscrossing pattern of epidermal canals in posterior third of body as present in many congeners. 4-5 columns (mode 5) bilateral columns of electrocytes at anal-fin terminus, and 4-6 columns (mode 5) at or near a mid-point between anal-fin terminus and tip of caudal filament in immature, mature female, and mature male specimens. Number of electrocyte columns tapers rapidly to 2-3 at caudal filament tip. Caudal filament very short.

Coloration. ( Fig. 37 ). Background light to dark brown, fading ventrally. Dorsal region without prominent depigmented pale stripe extending along midline from occipital region to base of caudal filament. Dorsal region very dark, with irregular mottling of lighter background pigmentation, no prominent vertically oriented stripes or bands. Ventral flank over body cavity and anal-fin pterygiophores with distinctive irregular marbled pattern of fused dark brown patches over lighter background. Caudal filament darker than body, with or without irregular light patches. Head with evenly scattered dark chromatophores, darker dorsally. Eye without prominent suborbital patch, or stripe, of chromatophores/subcutaneous pigmentation. Pectoral and anal-fin membranes hyaline. Pectoral and anal-fin rays hyaline with light scattering of melanophores. Color in live individuals similar to preserved specimens, with opercular region slightly rosy due to underlying gills.

Size. Moderate adult size, largest specimen examined 203 mm TL, 184 mm LEA (n = 85). Largest male specimen examined 203 mm TL, 184 mm LEA (n = 2). Largest female specimen examined 157 mm TL, 151 mm LEA (n = 4).

Sexual dimorphism. Sexually mature males attain larger sizes than females, and exhibit substantially deeper caudal filaments than immature individuals and breeding females ( Figs. 37 a-b), but do not exhibit an elevated number of horizontal bilateral columns or vertical rows of electrocytes. Instead breeding males exhibit clearly enlarged electrocytes relative to immature specimens and females. Large males often with slight paddle-like lateral compression at caudal filament tip ( Fig. 37b ), which is sometimes free of electrocytes distally. No known sexual dimorphism in pigmentation.

Geographic distribution. Ecuador ( Fig. 36 ). Known from two large Pacific drainages, the río Esmeraldas and río Guayas. Known also from the río Santiago, a smaller Pacific drainage in northern Ecuador, and from the río Siete, a small drainage of the Gulf of Guayaquil.

Ecological notes. Known from small streams and rivers to an altitude of ca. 650m. The type series of B. palenque was collected in a small clearwater streams (up to about 1m wide and 20-30 cm deep) in protected secondary rainforest. The substrate of these streams comprised clay, pebbles, rocks up to about 30 cm in diameter, leaf litter, and decaying logs. The following water parameters were recorded: conductivity 52 μScm-1, dissolved oxygen 6.8 mgl-1, temperature 23.6-23.8°C, pH 6.5, and flow 0.05-0.2 ms-1. All specimens were collected from leaf litter or submerged root mats; usually up against or under logs or large rocks. Several fully mature male and female specimens were collected, and all were spaced at least 0.5 m apart except for a large male and female which were located in very close proximity (ca. 10 cm) and captured in the same net. Scattered along a 10-15 m stretch of stream were many (ca. 20 or more estimated from a fish-finder survey) very small specimens in the size range 19-40 mm (5 vouchered in UF 180271), which were difficult to collect because they passed through the mesh of the dip net. There was no sign of aggregations of post-larval specimens, as observed for B. beebei by Westby (1988). The population at the río Palenque Scientific Center was evidently breeding in mid- April 2004, when the type series was collected. However, the full extent of the breeding season is unknown. Stomach contents of specimens from the type locality comprise aquatic invertebrates, predominantly larval Chironomidae and Coleoptera (WGRC unpublished data). Barriga (1994) reports an omnivorous diet.

Co-occurring congeners: None.

Etymology. The specific name derives from the río Palenque, a Pacific Ocean drainage of Ecuador, where the type series was collected. A noun in apposition.

Local names. Ecuador: Cuchillo, bío-bío, anguila ( Barriga, 1991).

Figures

Fig. 37. Brachyhypopomus palenque. a. UF 180270 (WC05.160404), holotype, female, 149 mm TL (head in lateral view, and body in lateral and dorsal view, specimen fixed in formalin and preserved in EtOH); Ecuador, río Palenque, río Guayas dr. b. USNM 247230, male, 171 mm TL (body in lateral view, specimen fixed in formalin and preserved in EtOH); Ecuador, río Quinindé, río Esmeraldas dr. Note sexual dimorphism in caudal filament height. Scale bars = 5 mm.

Fig.36. CollectionrecordsforBrachyhypopomusoccidentalis (circles) and B. palenque (squares). The lectotype location for B. occidentalis and holotype location for B. palenque are marked with open symbols. Elevation data refers to altitude above mean sea level (see Fig. 2 for legend).