Ancistrus malacops ( Cope, 1872 )

Provenzano, Francisco & Barriga-Salazar, Ramiro, 2018, Species of Ancistrus (Siluriformes, Loricariidae) from Ecuador, with the description of a new species from the Amazon River Basin, Zootaxa 4527 (2), pp. 211-238 : 227-230

Ancistrus malacops ( Cope, 1872)

Tables 4, 5, Figures 2 , 3 , 7 , 10 , 11

Chaetostomus malacops Cope, 1872 . Proceedings of the Academy of Natural Sciences of Philadelphia, v. 23:287, Pl. 15 (fig. 3). Ambyiacu (Ampiyacu?) River, Peru. Syntypes: ANSP 8299 (2, disintegrated).

Xenocara occidentalis Regan, 1904 . Transactions of the Zoological Society of London v. 17, pt 3, no. 1: 257, Pl. 14, fig. 5. Canelos, eastern Ecuador. Syntypes: (7) BMNH 1880.12.8.69-74 (6).

Ancistrus lineolatus Fowler, 1943 . Proceedings of the Academy of Natural Sciences of Philadelphia v. 95: 255, figs. 44-47. Río Orteguasa, Florencia, Caquetá, Colombia. Holotype (unique): ANSP 70517 .

Ancistrus malacops Isbrücker, 1980:70 . Ortega & Vari, 1986:16. Burgess, 1989:437. Isbrücker, 2001:25, 26. Isbrücker, 2002:12. Fisch-Muller, 2003:377. Ferraris, 2007:222. Barriga S., 2012:113.

Ancistrus occidentalis Isbrücker, 1980:71 , Burgess, 1989:437, Isbrücker, 2001:25, 32, Isbrücker, 2002:12, Fisch-Muller, 2003:377, Ferraris, 2007:223.

Material examined. All from Ecuador. Morona-Santiago province: MEPN-10535, 6, 73.8–144.5 mm SL, Río Chiguaza, camino a Huamboya, 01°59’17”S 77°56’44”W, S. Rampon, August 1956. MEPN-17986, 1, 77.7 mm SL, Río Shaime en la vía Santiago-Méndez, afluente del río Morona , 02°56’54”S 77°46’51”W, R. Barriga, P. Arguello, E. Calvache, F. Cugushi, 12 November 2015 . MEPN-17987, 7, 45.8–86.0 mm SL, Río Wawaimi entre Pto. Morona y río Shaime, afluente del río Morona , 02°56’02”S 77°44’37”W, R. Barriga, P. Arguello, E. Calvache, F. Cugushi, 13 November 2015 . Napo province: MEPN-8182, 5, 80.2–113.6 mm SL, Río Chililin, 12 km E de la carretera vía Auca , km 57, 00°48’54”S 76°47’57”W, R. Barriga, 25 May 1996 . MEPN-9000, 2, 51.5–84.5 mm SL, Río Apayacu, a 2 km de la Estación Jatun Sacha, Ahuano , 00°04’43”S 77°46’59”W, R. Barriga, B. Bohger, G. Tapuy, 23 April 1999 . MEPN-9139, 1 ,, 108.3 mm SL, Río Sardinas a 6 km W de la Estación Biológica Jatun Sacha, Ahuano , 01°04’43”S 77°39’59”W, R. Barriga, B. Bohger, G. Tapuy, 23 April 1999 . MEPN-9140, 3, 95.2– 126.0 mm SL, Río Apayacu a 2 km de la Estación Jatun Sacha, Ahuano , 00°04’43”S 77°46’59”W, R. Barriga, B. Bohger, G. Tapuy, 23 April 1999 . MEPN-9141, 1, 138.5 mm SL, Río Pillisyacu 6 km al Noreste de Jatun Sacha, Ahuano , 01°05’57”S 77°36’15”W, R. Barriga, B. Bohger, G. Tapuy, 23 April 1999 . MEPN-11716, 8, 96.3–140.0 mm SL, Río Suno, junto a Caimitoyacu , 00°27’30”S 77°37’52”W, R. Barriga, 0 9 September 1996 . MEPN-11730, 7, 60.0– 111.8 mm SL, Río Burroyacu afluente del río Huataraco , 00°42’39”S 77°26’22”W, R. Barriga, 13 September 1996 . Orellana province: MEPN-2384, 4, 93.6–108.7 mm SL, Estero sin nombre, 20 km al W del Pueblo Edén, afluente Río Cariyuturi , 00°34’35”S 76°06’56”W, R. Barriga, L. Salazar, D. Stewart, 28 February 2003 . MEPN-10249, 26, 35.0– 85.7 mm SL, Estero Sunka a 20 minutos 1/ 2 km del Pozo de Petróleo Sunka. Afluente del Río Tivacuno , 00°40’48”S 76°43’29”W, R. Barriga, J. Tivirán, 0 2 December 1988 . MEPN-10322, 9, 84.5–148.1 mm SL, Río Cotapino, Alto Napo, 00°44’21”S 77°31’36”W, M. Olalla, August 1966 . MEPN-11556, 1, 108.9 mm SL, Río Chambira, afluente del río Tiputini , 00°37’51”S 76°30’59”W, R. Barriga, J. Silva, 19 May 2008 . MEPN-11648, 4, 45.8–80.1 mm SL, Río sin nombre afluente del río Cononaco , 00°58’56”S 76°59’18”W, J. Quilindaña, 12 July 2000 . MEPN-14858, 2, 75.6–87.0 mm SL, Río Huarmiyuturi, cerca al Helipuerto , 00°34’12”S 76°04’19”W, R. Barriga, 23 April 2009 . Pastaza province: MEPN-4476, 2, 92.8–101.9 mm SL, Canelos, río Bobonaza, 01°36’01”S 77°45’22”W, M. Olalla, April 1983 (Type locality of A. occidentalis ). MEPN-4652, 2, 72.0– 90.4 mm SL, Río Avispa , a 1500 m al W del pozo abandonado Manatí , 02°02’38”S 76°30’21”W, R. Barriga, A. Cartagena, A. Gavilánez, 0 9 May 1989 . MEPN-15405, 6, 92.5–114.9 mm SL, Bajos del Río Bobonaza, sitio equidistante entre Montalvo y Chicherota , 02°22’18”S 76°39’12”W, 17 February 1975 . Sucumbíos province: MEPN-4719, 1, 85.2 mm SL, Río Pushino, km 27 vía Lumbaqui-Puerto Coca, 4 km antes del pozo Rubí No. 2, 00°02’41”S 77°10’05”W, R. Barriga, L. Guatatoca, R. Chimbo, 0 5 May 1997 . MEPN-9272, 3, 81.5–100.8 mm SL, Río Ere, a 10 m de la casa de Ignacio Aguirre , 00°08’15”N 76°45’18”W, R. Barriga, A. Lusitante, 0 3 May 1995 . MEPN-10696, 3, 57.9–76.8 mm SL, Quebrada Yamanunka , km 16, drenaje pantano–charca, 00°18’00”S 76°39’41”W, R. Barriga, M. Cortez, 13 December 2010 . MEPN-10699, 1, 73.2 mm SL, Quebrada sin nombre en la Cooperativa 28 de Marzo , 00°02’17”S 76°39’15”W, R. Barriga, M. Cortez, J. Revelo, 14 December 2010 . MEPN- 15633, 2, 66.5–80.6 mm SL, Río sin nombre afluente del río Pañayacu , 00°24’46”S 76°04’22”W, R. Barriga, H. Machoa, 24 February 2010 .

Diagnosis. Ancistrus malacops differs from species inhabiting Amazonian Andean piedmont rivers, except A. latifrons , A. alga and A. shuar by the length of the mandibular ramus which fits 2.4–3.8 times in the interorbital width. In A. bufonius , A. marcapatae , A. montanus , A. heterorhynchus , A. boliviana , A. megalostomus , A. occloi and A. greeni , the reported mandibular ramus fits fewer than 2.0 times in the interorbital width. It further differs from A. latifrons , A. alga , A. megalostomus , A. lineolatus and A. tamboensis , by its interorbital width in head length, 2.3–2.8 vs. fewer than 2.3 times. In A. montanus and A. heterorhynchus the interorbital width fits 3.0 times in the head length. The species A. bufonius , A. jelskii , A. marcapatae , A. boliviana , A. occloi , A. greeni , and A. shuar have similar values of interorbital width. Among the species caught in eastern Ecuador, it is easily distinguished from A. alga by its color pattern, and shape of body and head. Values of cleithral width and interorbital width are 27.9%–31.8% SL vs. 34.3%–36.2% SL, and 13.4%–16.3% SL vs. 17.5%–20.5% SL, respectively. The differences with A. shuar are moderate or, in females, near none. But there is a tendency to have a more slender body and head. Values of cleithral width and interorbital width are 27.9%–31.8% SL vs. 30.3%– 32.5% SL, and 13.4%–16.3% SL vs. 14.4%–17.0% SL, respectively. Males of A. malacops are even more different in cleithral width 27.8%–30.2% SL vs. 30.7%–32.5% SL in A. shuar and 35.3%–36.2% SL in A. alga ; and interorbital width 13.5%–15.7% SL vs. 15.4%–17.0% SL in A. shuar and 20.1%–20.5% SL in A. alga ( Table 5).

Description. Morphometric data given in Tables 4 and 5. Body depressed anteriorly and, progressively become compressed posteriorly. Caudal peduncle compressed, deep and, robust. Dorsal profile of body convex from tip of snout through dorsal-fin origin. From there descending straight to adipose-fin origin, then straight and horizontal to caudal-fin origin. Ventral profile of body flat and straight or slightly concave. Ventral surface of head and belly naked until anal-fin origin. Urogenital papilla is not visible, in some mature males opening partially visible just posterior to anus ( Figs. 2 , 7 ).

Head moderately wide and depressed. Snout partially naked with or without fleshy cylindrical tentacles branched or not, its contour semicircular. In adult males, naked area is wider, and closer to nares or orbits. Females and juveniles have only narrow naked strip on snout border. Nostrils juxtaposed and closer to eyes than tip of snout. Eyes in dorsal lateral position, orbits not raised and without odontodes. Interorbital space is broad and flat or gently conv, Supraoccipital flat without ridges, posterior border straight and truncate. Movable hypertrophied cheek odontodes well developed, specimens can have 10–12. Size of these odontodes also is variable in each specimen, the longest odontode almost reaches to pectoral-fin origin independently of size of specimen. Anteriorly, base of movable hypertrophied odontodes are covered by plates. Opercular bone has an exposed surface easy visible externally, its lateral margin carries odontodes.

Mouth rounded or oval. Upper lip narrow, usually covering premaxilla and only external surface visible, its edge is almost horizontal, and with papillae very small. The internal surface papillose. Lower lip broad, its border with very minute undulations. Lower lip surface papillose. Papillae smaller near border of lip increasing in size near lower jaws. Papillae of anterior lip have similar size from those near lower jaws. Maxillary barbels short and free. Upper jaw larger than lower. Upper jaws straight and placed horizontally. Lower jaws forming a V between them. Teeth numerous and minute. Between 60-70 teeth in upper jaw and between 40-50 teeth in lower jaw. Premaxillary and dentary teeth of same size. Teeth incisor type, asymmetrically bifid, medial cusp longer and wider than lateral cusp. Medial cusp rounded or straight truncated, lateral cusp pointed. Tooth apex curved toward interior of mouth. Tooth apex yellowish, stalk whitish. Premaxillary and dentary without posterior papillae or ornamentation.

Lateral line plates 23–24. Post-anal plates 12–13. Inter-dorsal plates seven or eight, just in front of the spine of adipose-fin there is one plate with keel. Dorsal-fin origin is anterior to vertical through pelvic-fin origin. Dorsal-fin with one spine, followed by seven branched rays; when depressed their tips very close or reaching the adipose-fin origin. Adipose-fin always present and developed, but membrane is scarce. Adipose-fin spine wide and straight. Pectoral-fin with one spine, and six branched rays. Pectoral-fin spine reaches or surpasses half pelvic-fin spine length when depressed, and is longer than longest branched ray. Distal region of pectoral-fin spine with a fleshy tip, and, enlarged odontodes more developed in males. Pelvic-fin with one spine and five branched rays; its posterior margin surpasses anal-fin base when depressed. Anal-fin with one flexible spine and four branched rays. Distal margin of caudal-fin oblique truncate; lower spine longer than upper; caudal-fin rays i,14,i.

Sexual dimorphism. Adult males exhibit a wide naked area on snout. Tentacles are arranged in the following pattern: Snout edge with conical tentacles bordering, those near and at the tip are longest and branched. On dorsal midline, three to five tentacles, very long, and with many branches are present. Posteriorly, dorsal midline row split into two rows, oriented to the nostrils, with two or four tentacles branched each. Laterally to midline row, and anteriorly to rows close to nostrils, no tentacles are found, only a wrinkled and naked surface. On each side, in front of cheek odontodes, a row of three to five conical tentacles, runs from the snout edge to near eyes ( Fig. 7 ). In some cases one branched tentacle is present just in front of cheek odontodes. In some lots, we noticed that some adult males have small or very small fleshy tentacles. Females of A. malacops have a similar condition on snout tentacles to that observed in females of A. shuar ( Figs. 2 , 3 ).

Color. Head, and dorsolateral surface of the body varies from light to dark brown with whitish rounded blotches, evident or vanished, occasionally, rounded blotches may be blackish. Abdominal surface is lighter brown, uniform or with a great number of white or whitish dots. All fins with alternate combination of bands, blotches or dots, whitish or blackish, over rays and interradial membrane. Caudal-fin with a whitish or orange spot on its dorsal and ventral tips ( Figs.2 , 7 ).

Geographical distribution. Ancistrus malacops inhabits the eastern versant of Ecuador, from Sucumbíos province to Morona-Santiago province, except the Santiago River basin, apparently, the Morona River is the southern limit of the species ( Fig. 8 ).

Figures

FIGURE 2. Females of Ancistrus species, lateral view. From top to bottom: A. shuar, MEPN 17983, 93.9 mm SL. A. alga, MEPN 15169, 160.9 mm SL. A. clementinae, MEPN 5996, 100.1 mm SL. and A. malacops, MEPN 7804, 93.4 mm SL.

FIGURE 3. Ventral view of the head of females to show the presence (arrows) or absence of soft, fleshy tentacles on snout. A) A. clementinae, MEPN 5996, 100.1 mm SL. B) A. malacops, MEPN 7804, 93.4 mm SL. C) A. alga, MEPN 15169, 160.9 mm SL, D) A. shuar, MEPN 17983, 93.9 mm SL.

FIGURE 7. Ancistrus malacops, MEPN 14705, 117.8 mm SL, male. From top to bottom, lateral, dorsal and ventral view.

FIGURE 8. Map of Ecuador showing the geographical distribution of the species. A. shuar, star. A. alga, square. A. clementinae, circle. A. malacops, triangle. Symbols may represent more than one lot.

FIGURE 10. Ancistrus malacops juveniles, head close-up, dorsal view, showing the difference in naked surface on snout, between sexes, and the similar arrangement of soft, fleshy tentacles on edge. MEPN 10249, A) Female, 47.3 mm SL. B) Male, 46.3 mm SL.

FIGURE 11. Head close-up, dorsal view, male juveniles showing the difference in soft, fleshy tentacles. A) Ancistrus shuar, MECN-DP-1631, 50.85 mm SL. B) Ancistrus malacops, MEPN 17987, 45.8 mm SL.