Parotocinclus jacumirim, Silva-Junior & Ramos & Zanata, 2020

Silva-Junior, Dario Ernesto da, Ramos, Telton Pedro Anselmo & Zanata, Angela Maria, 2020, A new species of Parotocinclus with reduced adipose fin (Loricariidae: Hypoptopomatinae), from the rio Jacuípe basin, Bahia State, Brazil, Neotropical Ichthyology (e 190137) 18 (2), pp. 1-15 : 4-9

Parotocinclus jacumirim , new species urn:lsid:zoobank.org:act:9748E789-B3C4-48BC-8FF9-E888370C4C9D

( Figs. 1–2 ; Tab. 1)

Holotype. MZUSP 125761 , 34.5 mm SL, Brazil, Bahia State, Dias d’Ávila, rio Jacumirim, tributary of rio Jacuípe , on road BA-093 between municipalities of Dias d’Ávila and Mata de São João , 12°34’59.3”S 38°18’59.6”W, 5 Apr 2019, A. M. Zanata, P. C. Camelier, L. O. Silva & V. P. Abrahão.

Paratypes. All specimens from type locality . MZUSP 125762 , 2 , 29.4–33.2 mm SL , UFBA 8924 , 11 , 22.7–39.9 mm SL + 7 tissue samples, collected with holotype . UFBA 7562 , 25 , 36.8–47.5 mm SL, 2 c&s, 29.7–30.9 mm SL, 21 Apr 2013, A. M. Zanata , T. Ramos, L. Oliveira & T. Duarte . MCP 54426 , 3 , 28.6–37.3 mm SL ; UFBA 7600 , 22 , 39.9–50.7 mm SL ; UFPB 11971 , 3 , 32.3–33.6 mm SL, 5 Nov 2005, C. Figueiredo, A. M. Zanata . UFPB 12003 , 3 , 28.8–34.8 mm SL, 5 Jun 2013, C. Figueiredo, A. M. Zanata .

Diagnosis. Parotocinclus jacumirim is distinguished from its congeners, except P. bidentatus , P. cabessadecuia , P. dani , P. halbothi , P. muriaensis , P. pentakelis , P. seridoensis , and P. spilurus , by the possession of a reduced adipose fin, restricted to the adipose-fin spine (vs. adipose fin completely developed). The new species differs from P. bidentatus , P. halbothi , and P. muriaensis by lacking unicuspid accessory teeth (vs. unicuspid accessory teeth present), from P. bidentatus , P. cabessadecuia , P. dani , P. muriaensis , P. pentakelis , and P. spilurus by possessing broad naked abdominal areas between lateral and medial patches of plates (vs. abdomen without broad naked areas, covered by small or large platelets); and from P. seridoensis by having the snout tip completely covered by plates and odontodes (vs. naked area at snout tip).

Description. Standard length of examined specimens 24.0– 50.7 mm SL. Measurements and counts in Tab. 1. Body elongate, without conspicuous keels, moderately depressed. Trunk trapezoidal, and caudal peduncle ellipsoid in cross section. Dorsal profile of body slightly convex from snout tip to supraoccipital process and slightly convex to straight from that point to dorsal-fin origin. Dorsal profile straight from dorsal-fin origin to caudal-peduncle midlength and somewhat concave from that point to origin of dorsalmost caudal-fin rays. Greatest body width at cleithrum, progressively tapering posteriorly, and greatest body depth at dorsal-fin origin, gradually tapering posteriorly to caudal peduncle. Ventral profile slightly concave from snout tip to cleithrum, straight to slightly convex from that point to anus, slightly slanted from anus to end of anal-fin base, almost straight along caudal peduncle.

Head rounded anteriorly in dorsal view. Interorbital region flat to slightly convex with supraorbital margins elevated. Snout elongate, depressed. Nostrils ovoid and positioned closer to anterior margin of orbit than from snout tip. Internareal area slightly elevated. Eye medium-sized, dorsolaterally positioned. Patch of slightly hypertrophied odontodes at posterior tip of supraoccipital bone. Odontodes on head equal in size to those on trunk, but border of snout tip with somewhat larger and curved odontodes. Mouth wide and lips rounded; lower lip with delicate fringed margin and not reaching transverse line between gill openings. Lips covered by papillae, except for region immediately behind dentary teeth; papillae of upper lip rounded and small; anteriormost papillae of lower lip digitiform and large, decreasing in size towards lower-lip margin. Teeth slender and bicuspid. Blade-like medial cusp inward curved and approximately three times longer than pointed lateral cusp. Accessory unicuspid teeth absent.

Body entirely covered by dermal plates, except for naked areas around lips, nares, paired-fin bases, parts of abdomen, and anus. Trunk covered by five longitudinal series of dermal plates. Somewhat aligned odontodes covering most of lateral plates, forming parallel to somewhat divergent rows; rows usually more conspicuous on posterior half of body; odontodes slightly larger on posterior border of plates. Median series of lateral plates bearing complete and uninterrupted lateral-line canals. Pored tubes of lateral line visible from compound pterotic to penultimate plate. Trunk plates without keels. Pectoral girdle partially exposed, with anterior medial portion covered by skin. Arrector fossae large and medially positioned. Laterals of abdomen with patch of plates, positioned between coracoid and pelvic fins, isolated from median abdominal plates by broad naked areas; some large specimens (larger than 35 mm SL) with lateral and median patch of plates somewhat connected by a few small plates but with broad naked areas anteriorly and posteriorly to the connection. Lateral patches oval and formed by large laterally elongate plates. Median patch pointed anteriorly close to coracoid and somewhat enlarged and rounded posteriorly, reaching area beyond pelvic-fin base; posteriormost plates usually larger than anterior most plates.

Dorsal-fin rays I,7, spine somewhat arched. Dorsal-fin origin slightly posterior to vertical through pelvic-fin origin. Dorsal-fin spinelet present, plate-like and slightly v-shaped, articulated to first dorsal-fin pterygiophore. Pectoral-fin rays I,6. Pectoral fin with large spine slightly arched; tip of adpressed spine reaching between proximal third to half of pelvic-fin length. Pelvic-fin rays i,5; tip of adpressed fin reaching to anal-fin origin in males, shorter in females. Adipose-fin reduced to poorly visible elevation situated at typical adipose-fin position and adipose-fin membrane absent (type 2 described in the Material and Methods); slightly arched adipose-fin spine visible in c&s specimens, similar in size compared to congeners with adipose fin completely developed; adipose-fin spine not merged to caudal peduncle but juxtaposed to it. Anal-fin rays i,5. Caudal-fin rays i,14,i, with lower unbranched ray slightly longer than upper. Vertebral centra 27 (1), 28 (1), and seven pleural ribs (2).

Coloration in alcohol. Overall ground color of dorsal and lateral surface of head and trunk pale yellow or light brown ( Fig. 1 ). Black chromatophores sparsely distributed on head and body, rarely on belly; brown chromatophores more rarely distributed between black chromatophores. Dorsal surface of head from interorbital to posterior end of supraoccipital darker than snout. Snout usually with black chromatophores homogeneously distributed; some small specimens (up to 30 mm SL) with chromatophores forming distinctly dark patches isolated from each other by clearer areas; dark patches on laterals of head of such specimens forming rough dark narrow stripe from tip of snout to opercle. Dark broad midlateral stripe from rear of opercle to end of caudal peduncle; dorsal and ventral borders of stripe inconspicuous in some specimens; dorsal margin merged with dark vertical bars. Four transverse dark bars crossing dorsal half of body; first bar situated on anterior portion of dorsal-fin base, second aligned to final third of dorsal-fin rays, third aligned to distal half of anal-fin rays, and fourth positioned just ahead of caudal-fin origin. Rays of dorsal, anal, pectoral, and pelvic fins with alternation of dark and clearer bands formed by concentration of black and brown chromatophores, respectively; bands less evident on unbranched rays; interradial membranes hyaline, except on caudal fin. Caudal fin with black and brown blotches, not forming bands; black blotches mainly concentrated on lower lobe and formed by pigmentation of portions of rays and interradial membranes. Ventral surface pale yellow, with black chromatophores sparsely distributed on borders of head, laterals of body, and posterior to anus.

Color in life. Pattern of dark bars and stripes in freshly collected specimens similar to preserved specimens, although somewhat less evident, and clear brown background color ( Fig. 2 )

Sexual dimorphism. Mature males of Parotocinclus jacumirim have urogenital papilla positioned immediately posterior to the anal opening, a structure absent in females. Males also differ from females by having longer pelvic fin, with tip of first unbranched ray ending posteriorly to the anal-fin origin, and by the presence of a skin flap along the dorsal portion of the first unbranched pelvic-fin ray. In females, the pelvic fin ends anteriorly or close to the anal-fin origin and there is no skin flap on the first pelvic-fin ray. Additionally, males of P. jacumirim have the posterior nostril aperture approximately two times broader than females.

Geographical distribution. The new species is known from the rio Jacumirim, a tributary of the rio Jacuípe, a relatively small independent drainage situated in Bahia State, with headwaters between municipalities of Conceição do Jacuípe and Amélia Rodrigues, and emptying directly in the Atlantic Ocean ( Fig. 3 ).

Ecological notes. The rio Jacumirim is within the geographical Atlantic Forest domain, in area once dominated by Atlantic Forest but currently altered by anthropic actions. The sampled river stretch is approximately one meter wide, varying from a few centimeters up to one meter deep, characterized by having fast water flow, substrate formed mainly by peebles, sand and organic debris, and marginal vegetation with dense grass bushes, sparse trees, and palm trees ( Fig. 4 ). Parotocinclus jacumirim was collected syntopically with Atyanax aff. fasciatus Cuvier, Poecilia reticulata Peters , and a species of Rhamdia Bleeker.

Etymology. Named after the rio Jacumirim, the type locality and the only river where the species is known up to date. The specific name, jacumirim , from the Tupi indigenous language “Jacu” from “Jacuípe”, meaning the river of jacús, a species of bird, and “mirim”, meaning small. A noun in apposition.

Conservation status. Up to date, Parotocinclus jacumirim possesses a relatively small known distribution, collected at just one locality of the rio Jacuípe basin. The area drained by the basin is anthropically altered and the collecting site is within an industrial region of Bahia, in the surroundings of the Pólo Industrial de Camaçari. However, no adequate information is available to make direct, or indirect, assessments of extinction risk based on the distribution and/or population status of the species. Therefore, P. jacumirim could be classified as Least Concern (LC), according to the International Union for Conservation of Nature Standards and Petitions Committee (IUCN, 2019).

Figures

FIGURE 1 | Parotocinclus jacumirim, holotype, MZUSP 125761, female, 34.5 mm SL, rio Jacumirim, tributary of rio Jacuípe, on road BA-093 between municipalities of Dias d’Ávila and Mata de São João, Dias d’Ávila, Bahia, Brazil.

FIGURE 2 | Parotocinclus jacumirim, live paratype, UFBA 8924, not measured, rio Jacumirim, tributary of rio Jacuípe, on road BA-093 between municipalities of Dias d’Ávila and Mata de São João, Dias d’Ávila, Bahia, Brazil.

FIGURE 3 | Distribution of Parotocinclus jacumirim (red star), rio Jacumirim, tributary of rio Jacuípe, on road BA-093 between municipalities of Dias d’Ávila and Mata de São João, Dias d’Ávila, Bahia, Brazil.

FIGURE 4 | Type locality of Parotocinclus jacumirim, rio Jacumirim, tributary of rio Jacuípe, on road BA- 093 between municipalities of Dias d’Ávila and Mata de São João, Dias d’Ávila, Bahia, Brazil.