Otocinclus batmani, a new species of hypoptopomatine catfish (Siluriformes: Loricariidae) from Colombia and Peru

A new species of the hypoptopomatine catfish genus Otocinclus is described from two localities in the upper Río Amazonas basin: a tributary of the Río Puré in Colombia and two tributaries to the Río Amazonas near Iquitos in Peru. The new taxon can be easily distinguished from all congeners, except Otocinclus cocama, by having a single, intensely pigmented, vertical Wshaped caudal fin spot and by having three discrete dark bands on dorsum, between the dorsal-fin base and the caudal fin. Otocinclus batmani differs from O. cocama by the absence of vertically elongated blotches from the dorsal midline to the ventral border of flanks, and by lacking a posterior extension of black pigmentation on the base of two central caudal-fin rays. Phylogenetic relationships of the new species are investigated and it is possibly more closely related to a clade formed by O. huaorani, O. mariae, O. bororo, O. mura, and O. cocama.


Introduction
The genus Otocinclus Cope, 1871 is composed of 16 species of small (less than 60 mm SL) freshwater catfishes distributed in the Neotropics from Colombia to northern Argentina, occurring in tributaries to the east of the Andes (Schaefer, 2003).Schaefer (1997) revised the genus and recognized 13 species.Britto & Moreira (2002) described Otocinclus tapirape from the rio Araguaia basin in central Brazil and reexamined the phylogenetic relationships within the genus.Axenrot & Kullander (2003) recently added O. mimulus from the Río Parana in Paraguay, and Reis (2004) described O. cocama from the Río Ucayali basin in Peru.These fishes are mostly herbivorous, are typically diurnal, and are usually found at or near the water surface, typically in close association with marginal vegetation or subsurface structures (Schaefer, 2003).Otocinclus is a basal member of the tribe Hypoptopomatini and is believed to be monophyletic (Schaefer, 1997) on the basis of several synapomorphies, especially of the cranial and hyobranchial skeleton, dorsal gill arch musculature, and gut.Otocinclus shares with Acestridium, Hypoptopoma, Nannoptopoma, Niobicthys, Oxyropsis, and a new taxon from Brazil and Colombia, a reduced preopercle.Schaefer (1997) also provided a set of hypotheses for its biogeographic history.The phylogenetic relationships among the hypoptopomatines are currently under study, and the genus Otocinclus may eventually be relocated.In this paper, Otocinclus batmani is described from Colombia and Peru in the upper Amazon River basin.

Material and Methods
Counts, morphometrics, and nomenclature follow Schaefer (1997), Britto & Moreira (2002), Douglas et al. (2002), and Axenrot & Kullander (2003).Specimens studied were cleared and stained (c&s) using the methods of Taylor & Van Dyke (1985).Counts listed in the text are followed by their frequency in parentheses, an asterisk indicating values for the holotype.The specimens examined belong to the following institutions: ANSP, Academy of Natural Sciences, Philadelphia; Total plates in median lateral series 23.Lateral line discontinuous; anterior field of canal-bearing lateral line with 6*(6) or 7(4) plates; posterior field with 8(3) or 9*(7) plates and separated from anterior field by gap of 6(4) or 7*(6) non canalbearing plates.Greatest body depth at dorsal-fin origin.Dorsal fin when depressed reaching to vertical through posterior third of anal fin.Pectoral fin reaching to proximal third of pelvic-fin length; pelvic fin almost reaching to anal-fin origin.
Abdomen with paired series of 7(5) or 8*(5) large, rectangular, median plates arranged in irrregular series and becoming smaller and more irregularly shaped posteriorly; pre-anal plate well developed, continuous with median abdominal plates only in specimens above 30 mm SL.
Arrector fossa closed.Odontodes evenly distributed and regularly arranged on head and body; those on margins of snout only slightly larger than those on remainder of head.Enlarged odontodes along distal portion of unbranched rays of all fins, procurrent rays, and edges of caudal peduncle.Lateral margins of nuchal plate reduced, not expanded over transverse processes of first dorsal-fin radial.Dorsal fin II,7*(9) or 8(1); pectoral fin I,6; pelvic fin i,5; anal fin i,5; caudal fin i,14,i*(9) or i,13,i(1).Dorsal and ventral caudal-fin lobes equal in length.Dorsal procurrent rays two or three, ventral procurrent rays two or three.Vertebrae 22, excluding those incorporated into Weberian complex.
Color in alcohol.Ground color pale yellow.Complex pattern of melanophores along entire dorsal surface of head and trunk; occasionally concentrated in diffuse clusters between supraoccipital and dorsal-fin origin and with three discrete bands along midline between dorsal-fin base and caudal fin.Head and trunk with distinct midlateral stripe composed of superficial and deep-lying melanophores extending from snout (pre-nasal plates) to base of caudal-fin rays; pigment especially concentrated in region immediately ventral to margin of pterotic-supracleithrum and posterior to dorsal margin of opercle.Caudal fin with one W-shaped vertical mark in distal half, heavily pigmented, from middle portion to poste-rior fin margin.Pigmentation along median rays between caudal-fin base and W-shaped mark always absent.Modally three uppermost and three lowermost caudal-fin rays with unpigmented tips.Middle rays 4-11 typically pigmented to distal margin.Pigmentation in dorsal fin concentrated in 3-4 distinct blotches along spine; two bands on branched rays; interradial membranes unpigmented.Anal fin unpigmented.Pectoral fin with 3-4 blotches along spine; branched rays and interradial membranes unpigmented.Pelvic fin unpigmented.Ventral surface of head and body mostly unpigmented (Fig. 1).
Distribution.Otocinclus batmani is known from the typelocality, a small stream tributary to the Río Puré in Colombia, and from two creeks emptying into the Río Amazonas near Iquitos, Peru, in the upper Amazon River basin (Fig. 2).
Etymology.The name batmani, alludes to Bob Kane's hero Batman of the comic adventures, which had a bat shape for his symbol, referring to the single W-or bat-shaped vertical spot on the caudal-fin.

Discussion
This new species is most probably closely related to the clade B of Schaefer (1997: 103), which originally included Otocinclus bororo, O. mariae, O. mura, and O. huaorani, supported by the presence of 20 or more teeth in both the premaxilla and dentary (character 27).Otocinclus cocama also shares more than 20 teeth on upper and lower jaws, and should be included in the clade B as well.Within this group, the new species shares with O. cocama the presence of a single, intensely pigmented W-shaped caudal fin spot, which is here identified as a synapomorphy uniting these two species.
The first anal-fin pterygiophore is exposed ventrally in Otocinclus batmani, O. hasemani, O. hoppei, O. huaorani, O. macrospilus, O. mariae, O. mura, and O. vittatus.In callichthyids, Astroblepus, delturines and neoplecostomines, the first anal-fin pterygiophore is covered by skin.In all members of the Loricariinae (Paixão, 2004) and Hypoptopomatinae, except for some Otocinclus species, and the Otothyrini sensu Schaefer (1998), the first anal-fin pterygiophore is exposed ventrally.Paixão (2004;character 67) proposed the first analfin pterygiophore exposed ventrally and with plates around it (state 2) as a synapomorphy for the Loricariinae.However, in most hypoptopomatines examined, the same condition was observed.This character may represent an informative condition among neoplecostomines and hypoptopomatines (Lehmann & Reis, in progress).Thus, the phylogenetic information of this feature should be verified in a future work on a revision of hypoptopomatines.
In callichthyids and most loricariids (Armbruster, 2004) the first dorsal-fin spine is a short, V-shaped structure, involved in the locking mechanism of the dorsal-fin spine in an upright position.In most otothyrins and some neoplecostomines, the spinelet is a rectangular, plate-like structure, and is not functionally a locking mechanism of the dorsal-fin spine.This spinelet is absent in all hypoptopomatins, but is present in all Otocinclus species (including the new species), which have a V-shaped spinelet and funtional locking mechanism of the dorsal-fin spine.

Table 1 .
ICNMHN, Instituto de Ciencias Naturales, Museo de Historia Natural, Universidad Nacional de Colombia, Bogotá; MCNG, Museo de Ciências Naturales, Guanare; MCP, Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre; MHNUC, Museo de Historia Natural de la Universidad del Cauca, Popayán; MZUSP, Museu de Zoologia da Universidade de São Paulo, São Paulo; Description.Counts and proportional metrics given in Table2.Standard length of examined specimens 23.2-36.7 mm.Dorsal profile of head from snout tip to dorsal-fin origin smoothly convex; straight between anterior margin of frontals and posterior supraoccipital tip.Dorsal profile of trunk from dorsalfin origin to dorsal procurrent caudal-fin rays slightly concave.Ventral profile of head and abdomen from snout tip to pelvic-fin base straight, transversely flat.Ventral profile of trunk straight between pelvic-fin base and anal-fin origin, concave between anal-fin origin and caudal peduncle.Cau- dal peduncle slightly rectangular in cross section.Snout tip smoothly rounded.Eyes moderately large, orbit center positioned approximately midway between snout tip and posterior process of pterotic-supracleithrum. Iris flap absent.Lateral ethmoid with expanded subnasal lamina.