Ancistrus yutajae, De & Taphorn & Armbruster, 2019

De, Lesley S., Taphorn, Donald C. & Armbruster, Jonathan W., 2019, Review of Ancistrus (Siluriformes: Loricariidae) from the northwestern Guiana Shield, Orinoco Andes, and adjacent basins with description of six new species, Zootaxa 4552 (1), pp. 1-67 : 58-61

Ancistrus yutajae , new species

( Fig. 28 )

Holotype. MCNG 7854 (1, 82.80 mm SL) Amazonas, Venezuela, Orinoco / Ventuari / Yutajé River , Yutajé River at the end of the airstrip at Campamento Yutajé, 6.146078 o, -61.492243 o 14-Feb-1981, S. Reid.

Paratypes. ANSP 205666 (2, 60.3–78.4 mm SL), AUM 71045 (2, 66.6–75.8 mm SL), and MCNG 2664 (1, 62.4 mm SL) Amazonas, Venezuela, Orinoco / Ventuari / Yutajé River , Yutajé River near campamento Yutajé, 15- Mar-1981, 5.547222 o, -66.115833 o, S. Reid ; MCNG 41745 (4, 39.8-50.1 mm SL) Amazonas, Venezuela, Orinoco / Ventuari / Yutajé River , Caño Yutajé near confluence of Rio Corocoro, 26-Mar-1999, 6.29835 o,-61.531858 o, S. Reid .

Diagnosis. Ancistrus yutajae can be separated from all other Ancistrus in the area by having the rows of tentacles barely diverging, almost parallel along the median line (vs. tentacles widely diverging in a V - or U- shape to almost straight and transverse), by having a rectangular naked patch centrally posterior to tentacles and extending to anterior margin of nares (vs. no central naked spot behind tentacles and naked area ending anterior to anterior margin of nares, also present in A. kellerae ); and by almost always having two or three branched anal-fin rays (vs. four, one specimen of A. yutajae has four); from all except A. amaris and specimens of A. triradiatus from the Río Orotoy of Colombia by having very long dentaries (minimum interorbital width divided by dentary length 1.24–1.76 vs. Ź1.91), and from A. amaris by having the longest tentacles of nuptial males about equal to orbit diameter (vs. less than orbit diameter). Ancistrus yutajae differs from other Ancistrus along the Andean piedmont with long jaws ( A. bolivianus , A. bufonius , A. greeni , A. heterorhynchus , A. marcapatae , A. megalostomus , A. occloi , A. sericeus , and perhaps A. jelksii ) by having the dorsal fin reaching the preadipose plate (vs. well short), by having the pectoral-fin spine when adpressed below pelvic fin reaching to beyond pelvic-fin base (vs. barely or not reaching pelvic fin), and by having the body relatively deep (vs. very depressed)

Description. Morphometrics given in Table 7. A relatively small-sized Ancistrus , body broadest anteriorly, greatest body width just posterior to opercles, then narrowing progressively to end of caudal peduncle. Head and body depressed, greatest body depth between level of pectoral-fin insertions and dorsal-fin origin. Caudal peduncle deep, robust, compressed posteriorly. Dorsal profile of head ascending steeply in convex arc from tip of snout to just posterior of orbits, ascending in straight line to posterior tip of supraoccipital, then descending to dorsal-fin origin. From the dorsal-fin origin descending in a slight convex arc to just posterior of dorsal-fin base, then straight to caudal fin. Ventral profile flat to slightly convex from tip of snout to pelvic-fin insertions. Abdomen flat to slightly concave to pelvic-fin insertions, from there, straight to slightly convex and sloping gently ventrally towards caudal fin.

Head wide, interorbital width equal or slightly less than head depth, slightly less than half of head length. Snout rounded with large broad naked margin in males, less wide in females and juveniles. Snout length about onehalf head length. Eye small in size, interorbital area slightly convex. Oral disk ovate, wider than long. Lips covered with minute papillae, larger near mouth. Lower lip moderate in size, not reaching gill aperture, its border covered with very small papillae. Maxillary barbel very short, its length less than orbit diameter. Jaws long with premaxillary tooth rows forming slight arc and dentary tooth rows almost straight (slightly less than 180°). Dentary and premaxillary tooth rows moderately curved medially, lateralmost dentary tooth lateral to lateralmost premaxillary tooth. Teeth numerous (82–145 per jaw ramus), asymmetrically bifid, medial cusp much larger and spatulate, lateral cusp minute and pointed, usually not reaching more than half length of medial cusp, equal in worn teeth. Hypertrophied cheek odontodes strongly evertible, 13–34, stout with tips hooked anteriorly, bases encased in thick fleshy sheaths. Exposed part of opercle small, roughly triangular with few odontodes.

Head smooth, bones on back of head not carinate; supraoccipital with margins between surrounding bones and plates usually clearly visible. Lateral plates not carinate, lateral line pores distinctly visible, horizontally elongate.

Ventral surface of head and abdomen naked, no exposed platelets anterior to anal-fin spine. Nuchal plate small and curved posterolaterally. No enlarged odontodes at edge of lateral plates. Five series of lateral plates anteriorly, three series on caudal peduncle, mid-dorsal and mid-ventral plate series end on caudal peduncle beneath preadipose plate just anterior to embedded adipose-fin spine. Last plate in median series slightly smaller than penultimate plate, and median plate below end of adipose fin about twice as high as wide. Base of caudal fin with five platelets covering bases of caudal-fin rays.

Dorsal-fin origin situated anterior to vertical through pelvic-fin insertion. First dorsal-fin ray elongate, just slightly longer than snout length; last dorsal-fin ray reaching first preadipose plate when depressed. Adipose-fin spine (if present) embedded, oriented parallel to horizontal axis of body, membrane present, not visible beneath spine. Pectoral spine short and stout, when adpressed ventrally rearching the insertion of the pelvic fin. Anal fin small but well developed; base of first anal-fin pterygiophore covered by skin, its origin below or posterior to vertical through base of last dorsal-fin ray. Pelvic fins reaching well past anal-fin origin, inserted posterior to vertical through first branched dorsal-fin ray. Caudal fin truncate, lower lobe longer than upper. Tiny odontodes present on body plates, largest on posterior margins of plates. All fin spines with small odontodes, more developed in pectoral-fin spine of males. All fin rays with tiny odontodes on rays.

Meristics (N=10). Mid-ventral plates 17–19, x= ̃18; median plates 21–23, x= ̃22; mid-dorsal plates 14–19, x= ̃ 18; plates bordering dorsal-fin base seven to eight, x= ̃seven; plates between dorsal and adipose fins six to seven, x = six; preadipose plates one to two, x= ̃ one. Fin-ray formulae: dorsal II,7; pectoral I,6; pelvic i,5; anal i,2–4, x= ̃ i,3; caudal i,14,i. Caudal procurrent spines: dorsal: five, ventral: three.

Sexual dimorphism. Snout tentacles of nuptial males short, largest 1.5 times eye diameter. Posteromedial tentacles diverging in almost parallel along anteriorly triangular snout plates that are covered in thick skin. Naked areas of snout without tentacles rugose, separated from naris by single, narrow plate; naked area wide, distance from anteromedial plate to snout greater than distance from anteromedial plate to line formed between anterior edges of nasal aperatures.

Color in alcohol. ( Fig. 28 ) Base color light brown with small light dots, mostly faded. Plateless area of snout and tentacles also light brown no spots. All fins light brown, no spots or bands. Ventral surface of head and abdomen tan to yellowish tan with small dots, oral disk yellowish, plates of ventral surface of caudal peduncle with posterior margins slightly darker brown, forming alternating light and dark pattern.

Life colors. Live color is unknown.

Distribution. Known only from the Yutaje River of Venezuela ( Fig. 7 ). Despite recent collecting in the area, no specimens other than those collected in 1981 were procured.

Etymology. Named after the Yutajé River where the holotype was collected, and in tribute to a legend of the indigenous people of the Panare and Makiritare tribes. According to the legend, the name Yutajé commemorates Yu and Taje, young lovers whose tribes were at war. Upon learning of their forbidden love, the Maquiritare chief ordered their capture. On a clear moonlit night the lovers found themselves cornered on the edge of a cliff and launched themselves into the void. In the air they invoked the god of waters, who took pity on them and turned them into twin waterfalls, which today intermingle to form the Yutajé Falls and the Yutajé River. The legend states that the lovers will someday return to their human forms, when their tribes unite to form a single people and peacefully inhabit the Guiana Shield lands. Treated as a noun in the genitive case.

Figures

FIGURE 7. Distribution of species of Ancistrus from the northwestern Guiana Shield and neighboring regions.

FIGURE 28. Ancistrus yutajae, holotype, in dorsal, lateral, and ventral views, MCNG 7854, 82.8 mm SL. Scale = 1 cm. Photos by J.W. Armbruster.