A new species of Aspidoras (Siluriformes: Callichthyidae) from a small coastal drainage in northeastern Brazil

A new species of Aspidoras from the rio da Dona basin, a small coastal river drainage in Bahia State, is described herein. The new taxon differs from its congeners by presenting infraorbital 1 with well-developed ventral laminar expansion, nuchal plate nearly reaching to or sometimes contacting posterior process of parieto-supraoccipital, anterior tip of nuchal plate just posterior to dorsal margin of first dorsolateral body plate, and blotches on dorsal half of dorsolateral body plates and/or ventral half of ventrolateral body plates fused with midlateral series of blotches, forming three or four enlarged and oblique black blotches.


Introduction
Aspidoras Ihering, 1907 comprises 22 valid species (Eschmeyer et al., 2016) of small armored catfishes that are relatively broadly distributed in Brazil, mainly in the central and northeastern regions.The only comprehensive study regarding the taxonomy of Aspidoras is by Nijssen, Isbrücker (1976), who redescribed the nominal species and described nine new ones.The monophyly of Aspidoras is more deeply investigated and currently well accepted (see Reis, 1998;Britto, 2003;Alexandrou et al., 2011).According to Britto (2003), the Aspidoras clade is supported by five synapomorphies: (I) posterior portion of mesethmoid wide, (II) frontal fontanel reduced, (III) parieto-supraoccipital with circular fossa, (IV) operculum compact, and (V) ossified portion of the pectoral spine very small, less than half the length of first branched ray.

Material and Methods
Morphometric and meristic data follow Reis (1997), with modifications of Tencatt et al. (2013).Measurements were obtained using digital caliper to the nearest 0.1 mm.Standard length (SL) is expressed in mm and all other measurements are expressed as percents of standard length, with the exception of subunits of the head, which are expressed as percents of head length (HL).Osteological analysis was performed on cleared-and-stained (c&s) specimens, prepared according to the protocol of Taylor, Van Dyke (1985).Material fixed directly in alcohol (mol) is given after the total number of specimens.Osteological terminology follows Reis (1998), except for parieto-supraoccipital instead of supraoccipital (Arratia, Gayet, 1995), compound pterotic instead of pteroticsupracleithrum (Aquino, Schaefer, 2002), and scapulocoracoid instead of coracoid (Lundberg, 1970).The suprapreopercle sensu Huysentruyt, Adriaens ( 2005) is treated here as a part of the hyomandibula according to Vera-Alcaraz (2013).Vertebral counts follow Britto et al. (2009).Frequencies of counts are given in parentheses in the text, and an asterisk indicates values for the holotype.Nomenclature of latero-sensory canals follows Schaefer, Aquino (2000), and that of preopercular pores follows Schaefer (1988).Homologies of barbels follow Britto, Lima (2003).Comparative data of Aspidoras brunneus were obtained from its original description and/ or high resolution photographs of type-specimens available from the All Catfish Species imagebase (NSF DEB-0315963).Museum collection codes follow Sabaj (2016).poorly to moderately developed in remaining species, see Britto, 1998: 363, fig. 5).The new species is distinguished from A. carvalhoi, A. fuscoguttatus, A. lakoi, A. maculosus and A. rochai by having the nuchal plate nearly reaching or sometimes contacting the posterior process of parietosupraoccipital, with the anterior tip of nuchal plate just posterior to the dorsal margin of first dorsolateral body plate (vs.nuchal plate relatively distant from posterior process of parieto-supraoccipital, with anterior tip of nuchal plate just posterior to second dorsolateral body plate); from A. menezesi, A. poecilus, A. raimundi, and A. spilotus by having blotches on the dorsal half of dorsolateral body plates and/or ventral half of ventrolateral body plates fused with midlateral series of blotches, forming three or four enlarged and oblique black blotches (vs.blotches on dorsal half of dorsolateral body plates and/or ventral half of ventrolateral body plates not fused with midlateral blotches; blotches not oblique).

Aspidoras kiriri, new species
Description.Morphometric data of holotype and paratypes in Tab. 1. Head compressed with slightly convex dorsal profile overall; bluntly triangular in dorsal view.Snout relatively large and pointed.Dorsal profile convex along snout; somewhat straight along interorbital region; slightly convex from that point to dorsal-fin origin; slightly convex along dorsal-fin base; straight to slightly concave from end of dorsal-fin base to adipose-fin spine; slightly concave along caudal peduncle.Ventral profile slightly convex from isthmus to anal-fin origin; slightly concave from that point to caudal-fin base.Body elongate; roughly elliptical in cross section at pectoral girdle, gradually becoming more compressed toward caudal fin.
Eye rounded, dorsolaterally positioned on head; orbit delimited dorsally by lateral ethmoid, frontal and sphenotic, ventrally by infraorbitals.Anterior and posterior nares close to each other, only separated by flap of skin.Anterior naris tubular.Posterior naris close to anterodorsal margin of orbit, separated from it by distance equal to naris diameter.Mouth small, subterminal, width larger than orbital diameter.Maxillary barbel elongate, reaching to anteroventral limit of gill opening in most specimens.Outer mental barbel slightly longer than maxillary barbel.Inner mental barbel fleshy, with base close to its counterpart.Lower lip moderately developed, forming small semicircular fleshy flap.Small rounded papillae covering entire surface of all barbels, upper and lower lips, snout and isthmus.Gill membranes united to isthmus.
Four branchiostegal rays decreasing in size posteriorly.Hypobranchial 2 somewhat triangular, tip ossified and directed toward anterior portion, posterior margin cartilaginous, ossified portion well developed, about twice the size of cartilaginous portion.Five ceratobranchials with expansions increasing posteriorly; ceratobranchial 1 with small process on anterior margin of mesial portion; ceratobranchial 3 with continuous posterolateral margin; ceratobranchial 5 with long anterior portion and toothed on posterodorsal surface; 29-30 (3) teeth aligned in one row.Four epibranchials similar in size; epibranchial 2 slightly larger than others, with small pointed process on laminar expansion of posterior margin; epibranchial 3 with triangular uncinate process on laminar expansion of posterior margin.Two pharyngobranchials (3 and 4); pharyngobranchial 3 with triangular process on posterior margin.Upper tooth plate oval; 34-40 (3) teeth aligned in two rows on posteroventral surface.Lateral-line canal entering neurocranium through compound pterotic, branching twice before entering sphenotic: pterotic branch with a single pore; preoperculomandibular branch conspicuously reduced, with a single pore close to postotic main canal.Sensory canal continuing through compound pterotic, entering sphenotic as temporal canal split into two branches: one branch giving rise to infraorbital canal, other branch entering frontal through supraorbital canal, both with single pore.Supraorbital canal branched, running through nasal bone.Epiphyseal branch of supraorbital canal relatively long; pore close to frontal fontanel; branch slightly shorter; pore closer to supraorbital main canal in some specimens.Nasal canal with three openings, first on posterior edge, second on posterolateral portion and third on anterior edge; second pore generally fused with first pore.Infraorbital canal running through entire second infraorbital, extending to infraorbital 1 and opening into two pores.Preoperculomandibular branch giving rise to preoperculo-mandibular canal, which runs through entire preopercle, leading to pores 3, 4, and 5, respectively.

Coloration in alcohol.
Ground coloration of body pale yellow to light brown (Fig. 1).Dorsal portion of head with concentration of small black chromatophores, from snout to posterior tip of parieto-supraocciptal and laterally on most of first dorsolateral body plate; interorbital region less pigmented in some specimens.Lateral portion of snout with black stripe between anteroventral portion of orbit and origin of maxillary barbel in most specimens; ventral portion of snout yellowish white with scattered dark chromatophores.Barbels poorly pigmented, black chromatophores scarce 6 e160118 [6] on dorsal portion of maxillary barbel.Opercle and cleithrum generally almost entirely black.Ventral surface of head and trunk pale yellow.Dorsal series of four black blotches, first at anterior portion of dorsal-fin base, second at posterior portion of dorsal-fin base, third at adiposefin base and fourth at caudal-fin base.Most specimens with three to four large black blotches along midlateral side of body variably coalesced to a series of dorsolateral blotches, often resulting in a single anterodorsally oblique large blotch; midlateral blotches also ventrally elongated by coalescence to blotches in ventral series; blotches around and posterior to anal fin sometimes reaching their counterparts at midventral line; some individuals without blotches along ventral portion of body.Few specimens without coalescence of those three longitudinal series of blotches, with somewhat rounded blotches on dorsolateral portion of body isolated from midlateral and/or midventral portion of body.Ground color of fins pale yellow.Dorsal fin with large triangular black blotch usually occupying anterior two thirds of fin proximally; distal margin of dorsal fin hyaline.Adipose-fin spine brown, membrane hyaline or with few sparse chromatophores.Pectoral-fin rays brown dorsally; interradial membranes and distal margin of rays hyaline.Pelvic fin usually hyaline; few chromatophores on dorsal portion of anterior rays in some specimens.Anal fin with diffuse black or dark brown wide bar across middle region of fin, from second to last branched fin ray, and formed by chromatophores over rays.Caudal fin with three to four transversal black or dark brown bars, formed by chromatophores concentrated over rays; membranes hyaline.

Coloration in life.
General color pattern similar to preserved specimens (Fig. 2).Dorsal half of head, opercle, cleithrum and dorsal portion of body with distinctly golden areas, mainly between dorsolateral black blotches.Ventral portion of body and fins whitish.
Sexual dimorphism.Males of Aspidoras kiriri (around 20.9-30.9mm SL) possess genital papilla lanceolate in shape, similar to that found in other members of Corydoradinae (Britto, 2003: 142, fig. 23).Females without papilla or projections, the condition typically found in females of other species within Corydoradinae.

Geographic distribution.
Aspidoras kiriri is known only from two headwater tributaries of rio da Dona, a small coastal drainage in eastern Bahia, Brazil (Figs. 6a-b).Ecological notes.The rio da Dona enters the Atlantic Ocean near Ilha de Itaparica, Bahia, and its headwaters drain the eastern slopes of Serra da Jibóia.The area is located in the Atlantic Forest and Caatinga domains sensu Ab'Sáber (1977), and includes mountains that reach 800 m above sea level and moist hillside forests characteristic of northern Bahia.The new species occurs in small streams crossing the Atlantic Forest, at 244-303 m above sea level.The Cai-Camarão tributary, type-locality of the new species, is 1-4 m wide and 20-40 cm deep, and has a rocky bed alternating with sand and organic debris.Specimens were sampled from small pools in stretches of rapids or larger pools below the rapids.The water temperature during the period of sampling was around 21.0 ºC, pH 4.55 and dissolved oxygen 7.3 mg/l.At this location, Aspidoras kiriri was sampled syntopically with Astyanax bimaculatus (Linnaeus, 1758), Astyanax sp., Characidium sp., and Trichomycterus sp.A second tributary, the rio Sururu is similar overall, but severely impacted where sampled, almost dry due to its proximity to road BA-495 and water removal for human use.The few specimens gathered from rio Sururu were found in very small mud-bottomed pools less than 10 cm deep.

e160118[7]
Etymology.Named after the Kiriri Indians who originally inhabited a broad area in eastern Brazil.Nowadays, they are restricted mainly to the municipality of Banzaê, in northern Bahia.The name of the indigenous people can be written as Cariri or Kariri and has its origin in the Tupi language, meaning silent, taciturn.A noun in apposition.
Conservation status.Populations of Aspidoras kiriri are currently known only from the rio da Dona basin, a relatively small drainage from Bahia State.Despite some records about threats for the region, such as deforestation, water pollution and erosion (Santos, Góis, 2004;Góis, Almeida, 2011), there is no data about direct effects of these threats to the populations of A. kiriri so far.Therefore, with the currently available data, and according to the International Union for Conservation of Nature (IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2016), A. kiriri should be classified as Least Concern (LC).

Discussion
According to the most recent phylogenetic studies (Alexandrou et al., 2011;Vera-Alcaraz, 2013), Aspidoras is paraphyletic since A. pauciradiatus and A. virgulatus are members of other clades.Despite that, A. kiriri can be unequivocally assigned to Aspidoras by having all the synapomorphies presented by Britto (2003) and a general morphological pattern very similar to A. rochai, type species of the genus, contrary to A. pauciradiatus and A. virgulatus, which are morphologically compatible with the species of lineages 4/5 and 3 sensu Alexandrou et al. (2011), respectively.

Tab. 1 .
Morphometric data of holotype and 20 paratypes of Aspidoras kiriri.The range includes the holotype.SD = standard deviation.