Poptella fortispina, Garcia-Ayala & Benine, 2023

Garcia-Ayala, James R. & Benine, Ricardo C., 2023, A new Poptella from the rio Xingu basin, Brazil (Characiformes: Characidae), Neotropical Ichthyology (e 220086) 21 (1) : -

Poptella fortispina , new species

urn:lsid:zoobank.org:act:8E1CD88D-B2A7-45B1-94C5-1F0D44C1914C

( Figs. 1–4, Tab. 1)

Poptella compressa . — Reis, 1989:24 (specimens examined). —Garcia-Ayala, Benine, 2017:571 (comparative material examined, specimens from rio Xingu).

Poptella sp. —Garcia-Ayala, Benine, 2019:7 (comparative material examined, specimens from rio Xingu). — Garcia-Ayala, Benine, 2021:7 (comparative material examined).

Holotype. INPA 59843 , 53.3 mm SL, Brazil, state of Pará , municipality of Altamira , igarapé Cobal, rio Xingu basin, 03°23’88”S 51°75’19”W, 8 Apr 2013, D. Bastos.

Paratypes. All from Brazil, rio Xingu basin. State of Pará : INPA 52827 , 39 (20, 38.3–60.8 mm SL), same data as holotype. ANSP 194605 , 1 , 31.7 mm SL, rio Bacajái , sand/gravel shoal and rocky outcrop ca. 2.2 and 3 river km, respectively, upstream from the confluence with rio Xingu , 03°35’30.4”S 51°45’156.3”W, 16 Sep 2013, M. H. Sabaj Pérez, L. M. Sousa, A. Gonçalves, N. K. Lujan, D. B. Fitzgerald, P. Madoka Ito, A. Oliveira, R. Robles & fishermen. ANSP 194636 , 10 , 31.0– 39.4 mm SL, rio Itatá ca. 1.1 river km upstream from confluence with right bank of rio Xingu , 03°37’15.7”S 51°49’14.1”W, 17 Sep 2013, A. O. Sawakuchi, J. L. Antinao Rojas, M. H. Sabaj Pérez & fishermen. ANSP 197062 , 1 , 22.4 mm SL, rio Bacajái , a shallow channel through forest and flooded sedges, ca. 5 river km upstream from the confluence with rio Xingu , 03°36’13”S 51°46’03.5”W, 10 Mar 2013, A. O. Sawakuchi, J. L. Antinao Rojas, M. H. Sabaj Pérez & fishermen. INPA 59846 , 4 , 31.4–37.4 mm SL, Travessão, rio Xingu , 08°17’41”S 55°12’67”W, 5 Aug 2015, F. C. T. Lima, O. Oyakawa, W. Ohara & M. Pastana. LBP 16680, 4, 38.3–40.5 mm SL, rio Xingu, 03°37’14.3”S 52°02’19”W, 30 Sep 2012, C. Oliveira, R. Britzke, L. M. Souza & D. Bastos. LBP 16681, 38 (24, 32.0– 40.2 mm SL), radiographed, 4 c&s, 32.6–38.9 mm SL, rio Xingu, unnamed creek, 03°30’14.3”S 52°02’19”W, 30 Sep 2012, C. Oliveira, R. Britzke, L. M. Souza & D. Bastos. LBP 17695, 2, 37.8–38.2 mm SL, rio Xingu, creek on road PA-279, 06°44’29.5”S 51°49’52”W, 18 May 2013, R. Britzke & M. Martins. MCP 54911 , 5 , 32.8–34.4 mm SL, rio Xingu, unnamed creek, 03°30’14.3”S 52°02’19”W, 30 Sep 2012, C. Oliveira, R. Britzke, L. M. Souza & D. Bastos. MZUSP 119361 , 5 , 26.4–46 mm SL, disctric of Castelo dos Sonhos, rio Xingu, creek on road BR-163, 08°17’41”S 55°12’67”W, 5 Aug 2015, F. C. T. Lima, O. Oyakawa, W. Ohara & M. Pastana. ROM 112950 , 5 , 31.3–33.8 mm SL, municipality of Altamira, rio Xingu , unnamed creek, 03°30’14.3”S 52°02’19”W, 30 Sep 2012, C. Oliveira, R. Britzke, L. M. Souza & D. Bastos. ZUEC 17550 , 5 , 30.8– 33.4 mm SL, Altamira, unnamed creek, 03°30’14.3”S 52°02’19”W, 30 Sep 2012, C. Oliveira, R. Britzke, L. M. Souza & D. Bastos. State of Mato Grosso, municipality of Gaúcha do Norte : MZUSP 94333 , 28 , 15 , 33.1–38.8 mm SL, marginal lagoon at the mouth of the ribeirão da Anta, just above the farm of the Mr. Zezé, rio Culuene , 13°30’51”S 53°05’49”W, 22 May 2007, F. C. T. Lima, F. A. Machado, C. A. Figueiredo & J. L. Birindelli. MZUSP 96886 , 8 , 38.1–54.9 mm SL, córrego do Lício tributary to rio Culuene , 13°50’22”S 53°14’59”W, 5 Oct 2007, F. C. T. Lima, F. A Machado, C. L Moreira, A. C. Ribeiro, O. Oyakawa, W. Ohara & M. Pastana .

Diagnosis. Poptella fortispina can be distinguished from all congeners by having a higher number of scale rows around the caudal peduncle (15–18 vs. 13–14). It can be further distinguished from P. brevispina , P. longipinnis , and P. fuscata by having fewer branched dorsal-fin rays (9 vs. 10–11). The new species is distinguished from P. compressa , P. paraguayensis , and P. actenolepis by having a comparatively robust, thick, broad, and downward curved predorsal spine (vs. delicate, thin, and narrow straight predorsal spine) ( Figs. 2, 4). Additionally, it can be distinguished from P. actenolepis by having more scale rows between the lateral line and dorsal-fin origin (8–10 vs. 7) and a comparatively elongated predorsal spine (4.3–5.5 vs. 2.8–4.2% mm SL).

Description. Morphometric data summarized in Tab. 1. Largest specimen examined 60.8 mm SL. Greatest body depth at dorsal-fin origin. Dorsal profile slightly convex between tip of snout and vertical through middle of orbit; slightly concave from this point to end of occipital process, and convex from tip of occipital process to dorsal-fin origin. Dorsal-fin base posteroventrally slanted. Profile straight or slightly convex from posterior terminus of dorsal-fin base to end of adipose fin. Caudal peduncle profile slightly concave both dorsally and ventrally. Ventral profile convex from tip of dentary to anal-fin origin. Body profile along anal-fin base straight and posterodorsally slanted. Prepelvic region compressed with median keel.

Mouth terminal. Distal tip of maxilla reaches vertical through anterior margin of pupil, not extending beyond third infraorbital. Premaxillary teeth in two rows; outer row with four*(110), rarely five (4) tricuspid teeth. Inner row with five*(113) or rarely six (1) pentacuspid teeth. Maxilla with one (37) or two*(75) conical or tricuspid teeth. Dentary with four teeth with five cusps, usually central cusp longest, and one small tricuspid tooth, followed by five to seven small conical teeth ( Fig. 3).

Dorsal-fin rays iii,9*(124). First dorsal-fin element modified into well-developed spine. Anterior end of predorsal spine rounded and ventrally concave, saddle-shaped

( Figs. 2–4). Predorsal-spine origin anterior to vertical through middle of standard length. First unbranched dorsal-fin ray shorter than second one. Second unbranched and first branched dorsal-fin rays slightly longer than following ones. Adipose fin present. Anal-fin rays iv* (124) or v (1), 25 (1), 27 (7), 28 (33), 29 (44), 30 (26), 31 (13), 32 (1). Pectoral-fin rays i,10 (20), i,11* (98) or i,12 (7). Posteriormost unbranched and first branched anal-fin rays longer than branched rays. Tip of pectoral fin reaching middle of when depressed pelvic fin. Pelvic-fin rays i,7* (125). Tip of pelvic fin reaching first two small unbranched anal-fin rays when depressed. Caudal fin i,16,i (1) or i,17,i (8). Dorsal procurrent caudal-fin rays 10 (2) or 11 (2); ventral procurrent caudal-fin rays 8 (3) or 9 (1). Caudal fin forked, lobes somewhat pointed and of similar size.

Scales cycloid, with two to six parallel radii. Lateral-line series with 35 (34), 36* (72) or 37 (19) perforated scales. Lateral line slightly curved downward. Predorsal scale series 1 (19), 2 (9) or 3* (3), irregularly arranged. Scale rows between dorsal-fin origin and lateral line 8 (20), 9* (50), or 10 (55). Scale rows between lateral line and midventral scale series 8 (4), 9* (70), or 10 (51). Scale rows around the caudal penducle 15 (48), 16 (23), 17 (25) or 18* (29). Small scales at base of anal fin in two series at first fin rays and becoming a single series extending to middle of anal fin. Small scales covering proximal two-thirds of caudal-fin lobes.

Total vertebrae 30 (10) or 31 (2). Supraneurals 3 (12) with bony lamellae on upper portion. First gill-arch with 13* (76), 14 (24) or 15 (3) gill rakers on ceratobranchial, 1* (103) on cartilage between ceratobranchial and epibranchial, and 9 (23), 10 (70) or 11 (10) gill rakers on epibranchial.

Coloration in alcohol. General body color yellowish. Dorsal portion of head and body darkly pigmented. Chromatophores concentrated on snout, jaws, dorsal portion of neurocranium and along dorsal midline of body. Posterior portion of scales slightly dark and generally delineated by dark chromatophores. Two vertically elongated humeral blocthes, extending up to six horizontal scale rows above lateral line and one scale row below lateral line, and separated by two horizontal scale rows. First blotch more conspicuous, with concentration of dark chromatophores forming a darker round blotch just above lateral line. Second humeral blotch faint. Narrow longitudinal dark line with chevron-like marks running along horizontal septum, extending from humeral region to caudal peduncle. Caudal peduncle blotch absent. Pectoral fin hyaline, with chromatophores scattered throughout interradial membranes. Dorsal, pelvic, and anal fins with scattered dark chromatophores concentrated along first rays and interradial membrane. Adipose fin with scattered dark chromatophores. Caudal fin with scattered dark pigmentation on its distal margin ( Fig. 1).

Sexual dimorphism. Mature males with small bony hooks on the unbranched and branched rays of the dorsal and anal fins. Dorsal fin with one to two hooklets on the distalmost segments of the posterior branch of the 2 nd to the 4 th branched rays. Anal-fin hooks unevenly distributed on the distalmost segments of the 1 st unbranched ray to the 26 th branched rays, being more numerous in the first twelve branched rays, with one to two hooks per segment.

Geographical distribution. Poptella fortispina is widely distributed in the rio Xingu basin, Pará and Mato Grosso states, Brazil ( Fig. 5).

Etymology. The name fortispina is from Latin “ fortis ” meaning strong and “ spina ” meaning spine, in reference to the robust predorsal spine.

Conservation status. Considering that no imminent threats to the species were

detected in area of occurrence, we suggest that Poptella forstispina be classified as least

concern ( LC) according to the International Union for Conservation of Nature ( IUCN)

categories and criteria ( IUCN Standards and Petitions Subcommittee, 2022).

Remarks. As demonstrated by Garcia-Ayala, Benine (2020), the number of branched dorsal-fin rays is helpful for the taxonomy of the Stethaprion Clade in properly separating the species of Poptella and Brachychalcinus . Poptella may be split into three groups according to the number of branched rays in the dorsal fin: nine, ten or eleven ( Garcia-Ayala, Benine 2020). Poptella fortispina is the seventh species described for the genus and shares with P. compressa , P. paraguayensis , and P. actenolepis the condition of nine branched dorsal-fin rays. Poptella brevispina and P. longipinnis have ten branched dorsal-fin rays and P. fuscata has eleven branched dorsal-fin rays (Tab. 2).

Along with the number of branched dorsal-fin rays, the length of the predorsal spine has been employed in the taxonomy of Poptella ( Reis, 1989; Garcia-Ayala, Benine 2019, 2020). Reis (1989) used the length of the predorsal spine as part of the diagnostic characters for the species of Poptella , indicating, however, overlapping ranges for P. compressa (3.1– 6.9% mm of SL), P. longipinnis (2.5–3.4% mm of SL), P. paraguayensis (4.7–6.4% mm of SL), and P. brevispina (2.6–4.2% mm of SL). The population of Poptella from the rio Xingu basin was first identified by Reis (1989) as P. compressa , due to the presence of nine branched dorsal-fin rays, adipose fin hyaline, and an elongated predorsal spine. Owing to the broad range and probably in an attempt to identify a putatively hidden diversity, Reis (1989) subdivided P. compress a into four populations named Guyana, rio Madeira, NE Brazil, and rio Orinoco. This procedure substantially reduced the range in each subgroup, except for NE Brazil, which kept values between 4.0% and 6.9% mm of SL. Reis’ (1989) NE Brazil included 32 specimens from tributaries of the rio Tocantins, rio Araguaia, rio Corda (Maranhão state), rio Parnaíba, and rio Xingu. Our analyses also showed more discrete subdivisions when these drainages were analyzed separately. Predorsal spines in specimens from the rio Tocantins-Araguaia vary between 5.4–7.0% mm of SL; from the rio Parnaíba, 3.9–4.9% mm of SL; and in specimens from the rio Xingu is 4.3–5.5% mm of SL. Therefore, these values indicate that the length of the predorsal spine may help distinguish specimens from the rio Xingu ( P. fortispina ) from those from the Tocantins-Araguaia basin. These differences, along with other diagnostic features (e.g., the number of scale rows around the caudal peduncle), indicate a hidden diversity in northeastern Brazil yet to be described.

Comparative material examined. Brachychalcinus retrospina Boulenger, 1892 : Brazil: NUP 879, 6, 39.7– 58.7 mm SL. Orthospinus franciscensis (Eigenmann, 1914) : Brazil: LBP 8105, 15, 42.5–53.9 mm SL. Poptella actenolepis : Brazil: MZUSP 117586, 15, 17.4–39.9 mm SL, paratypes. Poptella brevispina : Brazil: INPA 3493, 13, 50.5–63.1 mm SL; LBP 9332, 28, 54.3–88.2 mm SL; LBP 21127, 11, 29.4–44.3 mm SL. Poptella compressa : Guyana: ROM 87123, 10, 48.6–63.7 mm SL. Poptella longipinnis : Brazil: INPA 2220, 3, 43.5–50.3 mm SL; LBP 7792, 3, 33.6–37.7 mm SL. Suriname: MCP 11904, 2 59.4–64.1 mm SL. Venezuela: LBP 3060, 17, 34.8–42.3 mm SL. Poptella paraguayensis : Brazil: LBP 3826, 15, 39.9–57.9 mm SL; LBP 5114, 11 32.1–49.2 mm SL; LBP 9885, 10, 39–48.5 mm SL. Poptella sp. : Brazil: INPA 12329, 4, 34.8–36.4 mm SL; INPA 25677, 3, 31.6–46 mm SL; INPA 12329, 4, 34.8–36.4 mm SL; INPA 25677, 3, 31.6–46 mm SL; LBP 8777, 15, 26.7–46.5 mm SL; LBP 8881, 11, 31.2–38.9 mm SL; LBP 8882, 14, 33.1–38.3 mm SL; LBP 14115, 15, 56.7–70 mm SL; LBP 14204, 1, 52.5 mm SL; LBP 14241, 1, 44.2 mm SL; LBP 16213, 1, 39.1 mm SL; LBP 16222, 7, 38.5–68.2 mm SL; LBP 16228, 1, 36 mm SL; LBP 16268, 1, 50.5 mm SL; LBP 16408, 1, 54.4 mm SL; LBP 23782, 8, 38.2–57.1 mm SL; LBP 23782, 8, 37.4–46.4 mm SL; LBP 24486, 16, 31.8–38.3 mm SL; LBP 24495, 16, 41–50 mm SL; LBP 24496, 39, 40–45 mm SL; LBP 24498, 12, 36.1–42.1 mm SL; LBP 24497, 3 50.1–52.4 mm SL; MCP 22932, 15, 34.6–54 mm SL; MCP 38841, 5, 35.8–54.2 mm SL; MZUSP 89289, 39, 29.3–43 mm SL; MZUSP 89385, 20, 36.5–47 mm SL; MZUSP 92288, 10, 67.3– 39 mm SL; MZUSP 97276, 14, 30.2–35.5 mm SL; MZUSP 115653, 11, 34.8–45.4 mm SL; NUP 12724, 10, 36.8–44.1 mm SL; ZUEC 15196, 7, 29.6–36.9 mm SL. Peru: MCP 22939, 8, 29.8–42.7 mm SL; MZUSP 90585, 5, 36.8–43.4 mm SL; MZUSP 98723, 10, 33.9–46.1 mm SL; UMSM 23642, 10, 23.2–57.1 mm SL; UMSM 44773, 15, 56.4–66.3 mm SL; UMSM 47327, 11, 41.5–71.2 mm SL. Stethaprion crenatum Eigenmann, 1916 : Brazil: LBP 31261, 2, 67.8–68.1 mm SL.