Ancistrus yanesha Neuhaus, Meza-Vargas, Herrera & Lujan, 2023

Family:  Loricariidae (Armored catfishes), subfamily: Hypostominae
Max. size:  15.6 cm SL (male/unsexed)
Environment:  demersal; freshwater; depth range 0 - 1 m
Distribution:  South America: Peru.
Diagnosis:  This species is distinguished from all its congeners, except A. centrolepis, A. claro, A. luzia by having a color pattern of black vermiculated lines covering the head and two to four black parallel, lateral body stripes from head to caudal fin (vs. body uniformly colored or with dark or light spots or blotches over head and body); differs from A. centrolepis, A. claro, A. luzia by dark body stripes never forming dots or vermiculations (vs. dark spots in A. centrolepis, dark vermiculations in A. claro and A. luzia), from A. centrolepis by lateral plates lacking rows of enlarged odontodes (vs. lateral plates having enlarged odontodes in one to three crest-like rows), from A. claro by having deeper caudal peduncle 11.9%-13.4% (vs. 8%-10.7% SL), and from A. luzia by having longer dentary tooth cups 17.5%-22.2% (vs. 8.8%-18% HL). Regarding species described from the Ucayali River basin in Peru, A. yanesha differs from A. bufonius and A. occloi by the adpressed pectoral spine surpassing pelvic-fin unbranched ray insertion in specimens larger than 3.0 cm SL, reaching half-length of pelvic-fin unbranched ray in larger specimens (vs. pectoral spine not reaching or at most touching pelvic-fin unbranched ray insertion in larger specimens), by the lower lip never reaching anterior margin of pectoral girdle (vs. reaching or almost reaching its anterior margin), by having one preadipose plate (vs. keel formed by three or more preadipose plates), and from A. tamboensis by having longer premaxillary 17.6-20.7 (vs. 11.3-17.0) and dentary tooth cup length 17.5-22.2 (vs. 9.7-16.9) (Ref. 130912).
Biology:  This species was collected during the dry season in medium to large streams (20-25 m wide, 0.5-1.0 m deep) in the Palcazu River basin. It's habitats had clear, slow-flowing water and substrates of sand, gravel, boulders, leaf litter, and occasionally submerged wood. Other species collected in the same habitat were Attonitus irisae, Bryconamericus pachacuti, Creagrutus change, Knodus pasco, Odontostilbe sp., Characidium sp., Hoplias malabaricus, Crenicichla sp., Tahuantinsuyoa chipi, Astroblepus sp., Rhamdia sp., Chaetostoma lineopunctatum, Farlowella sp., Hypostomus sp, Rineloricaria lanceolata, and Sturisoma sp. (Ref. 130912).
IUCN Red List Status: Not Evaluated (N.E.) Ref. (130435)
Threat to humans:  harmless


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