Cetopsorhamdia clathrata, Bockmann & Reis, 2021

Bockmann, Flávio A. & Reis, Roberto E., 2021, Two new, remarkably colored species of the Neotropical catfish genus Cetopsorhamdia Eigenmann & Fisher, 1916 (Siluriformes, Heptapteridae) from Chapada dos Parecis, western Brazil, with an, Papéis Avulsos de Zoologia (Pap. Avulsos Zool., S. Paulo) 61, pp. 1-33 : 3-13

Cetopsorhamdia clathrata sp. nov.

http://zoobank.org/ 03CD1517-2543-4698-BDF0-9212BDEBDF4A ( Figs. 1-4 , Table 1)

Cetopsorhamdia new species 1. – Bockmann & Reis, 2011 [distribution – upper Rio Madeira basin, in State of Rondônia: unnumb. p.; brief characterization based

Rio Ji-Paraná (or Machado) basin Rio Roosevelt basin TOTAL H Min Max Mean SD N Min Max Mean SD N Min Max Mean SD N Total length (mm) 62.7 25.6 76.4 — — 13 45.4 93.8 — — 3 25.6 93.8 — — 16 Standard length (mm) 50.8 20.3 61.2 — — 13 35.5 72.7 — — 3 20.3 72.7 — — 16 1. Predorsal length 45.6 43.8 48.5 45.7 1.6 13 43.5 44.8 44.2 0.6 3 43.8 48.5 45.4 1.6 16 2.Preanal length 67.5 66.8 71.9 69.2 1.8 13 67.2 71.5 69.0 2.2 3 66.8 71.9 69.1 1.8 16 3.Prepelvic length 44.5 43.1 49.2 46.3 1.9 13 43.6 46.5 45.5 1.7 3 43.1 49.2 46.1 1.8 16 4.Preadipose length 72.9 69.5 75.4 72.4 1.9 13 69.2 73.3 71.3 2.1 3 69.2 75.4 72.2 1.9 16 5.Caudal-peduncle length 20.7 16.7 20.7 18.8 1.2 13 18.9 20.8 19.5 1.1 3 16.7 20.8 18.9 1.2 16 6.Caudal-peduncle depth 9.2 8.5 10.5 9.3 0.5 13 9.3 10.1 9.7 0.4 3 8.5 10.5 9.4 0.5 16 7.Adipose-fin length 14.4 13.7 16.2 15.2 0.7 13 15.3 17.1 16.4 1.0 3 13.7 17.1 15.4 0.9 16 8.Adipose-fin depth 3.9 3.4 5.7 4.4 0.6 13 4.4 4.6 4.6 0.1 3 3.4 5.7 4.4 0.6 16 9.Dorsal fin to adipose fin 18.8 13.0 18.8 16.5 1.5 13 15.6 18.6 17.2 1.5 3 13.0 18.8 16.6 1.5 16 10.Anal-fin base 12.3 12.3 15.3 13.7 1.1 13 12.8 13.5 13.1 0.4 3 12.3 15.3 13.6 1.0 16 11.Snout-anus distance 51.0 49.4 55.8 52.5 2.0 13 50.7 52.5 51.6 0.9 3 49.4 55.8 52.3 1.8 16 12.Snout-urogenital papilla distance 52.8 50.6 56.5 54.1 2.1 13 52.0 54.1 53.4 1.2 3 50.6 56.5 54.0 2.0 16 13.Anus-urogenital papilla distance 1.7 0.8 1.7 1.3 0.3 13 1.3 1.9 1.5 0.3 3 0.8 1.9 1.3 0.3 16 14.Length of first dorsal-fin ray (unbranched) 13.4 12.6 16.9 15.0 1.5 13 14.3 16.8 15.2 1.4 3 12.6 16.9 15.0 1.4 16 15.Length of rigid part of first dorsal-fin ray 4.8 4.0 6.9 5.7 0.8 13 5.5 6.2 6.0 0.4 3 4.0 6.9 5.7 0.7 16 16.Length of second dorsal-fin ray (first branched) 16.2 15.0 19.3 17.2 1.3 12 15.7 18.1 17.2 1.3 3 15.0 19.3 17.2 1.3 15 17.Length of third dorsal-fin ray (second branched) 15.4 15.1 19.2 17.1 1.6 13 17.0 17.5 17.3 0.3 2 15.1 19.2 17.1 1.5 15 18.Dorsal-fin base 10.2 9.5 11.6 10.7 0.7 13 10.1 11.3 10.7 0.6 3 9.5 11.6 10.7 0.6 16 19.Length of first pectoral-fin ray (unbranched) 14.1 12.4 15.1 13.7 0.9 13 13.6 14.5 14.1 0.4 3 12.4 15.1 13.7 0.9 16 20.Length of rigid part of first pectoral-fin ray 5.1 3.4 5.2 4.4 0.5 13 5.1 6.2 5.6 0.6 3 3.4 6.2 4.6 0.7 16 21.Length of second pectoral-fin ray (first branched) 15.5 13.7 16.1 15.1 0.7 13 15.4 16.6 16.1 0.7 3 13.7 16.6 15.3 0.8 16 22.Length of third pectoral-fin ray (second branched) 15.5 13.9 16.4 15.1 0.8 13 15.1 16.0 15.5 0.5 3 13.9 16.4 15.2 0.8 16 23.Length of first pelvic-fin ray (unbranched) 11.2 11.0 13.8 12.3 1.1 12 10.9 12.0 11.5 0.6 3 10.9 13.8 12.2 1.0 15 24.Length of second pelvic-fin ray (first branched) 13.1 12.8 15.3 14.3 0.8 12 13.9 15.0 14.4 0.6 3 12.8 15.3 14.3 0.7 15 25.Length of third pelvic-fin ray (second branched) 14.0 13.0 15.4 14.2 0.7 11 13.1 13.5 13.4 0.3 3 13.0 15.4 14.0 0.7 14 26.Length of dorsal caudal-fin lobe 23.0 19.8 24.3 22.8 1.3 13 22.6 26.2 24.0 1.9 3 19.8 26.2 23.1 1.4 16 27.Length of ventral caudal-fin lobe 26.2 20.3 27.9 24.8 1.7 13 25.7 29.6 27.4 2.0 3 20.3 29.6 25.3 2.0 16 28.Body depth 16.6 12.8 16.6 15.3 1.3 13 13.4 15.1 14.3 0.9 3 12.8 16.6 15.1 1.2 16 29.Body width 12.8 10.4 12.8 11.5 0.7 13 11.1 11.7 11.4 0.3 3 10.4 12.8 11.5 0.6 16 30.Cleithral width 17.8 16.2 18.2 17.2 0.6 13 17.2 18.3 17.6 0.6 3 16.2 18.3 17.3 0.6 16

Range Range Range

16 15 16 16 16 16 16 16 16 16 16 15 16 16 16

2.8 2.3 1.5 1.5 3.3 2.1 2.6 2.2 1.2 1.4 1.6 1.2 1.2 1.1 2.5

21.8 16.6 13.0 26.9 49.6 70.2 27.8 20.4 11.7 39.6 26.8 13.6 12.2 15.3 38.5

25.6 20.4 15.6 29.2 55.8 75.4 31.6 24.6 13.5 43.6 30.2 16.8 13.9 17.9 41.5

16.6 12.3 9.7 24.5 44.3 67.1 24.2 17.4 8.8 38.1 24.4 12.2 10.3 13.7 33.8

3 3 3 3 3 3 3 3 3 3 3 2 3 3 3

0.4 0.5 0.2 1.2 1.2 1.4 1.2 0.6 2.0 0.7 1.2 0.3 1.0 0.5 2.4

21.3 16.9 13.3 26.8 45.7 70.0 25.5 18.5 11.1 39.0 26.3 12.6 12.1 14.4 38.3 21.6 17.3 13.4 28.1 46.7 71.5 26.7 19.2 12.6 39.7 27.1 12.8 13.3 14.8 39.8

20.9 16.3 13.1 25.8 44.3 68.8 24.2 18.1 8.8 38.4 25.0 12.3 11.3 13.9 35.5

13 12 13 13 13 13 13 13 13 13 13 13 13 13 13

3.2 2.6 1.7 1.7 2.9 2.2 2.6 2.3 1.0 1.5 1.7 1.2 1.2 1.2 2.6

21.9 16.5 12.9 27.0 50.5 70.3 28.3 20.8 11.9 39.8 26.9 13.8 12.2 15.5 38.6 25.6 20.4 15.6 29.2 55.8 75.4 31.6 24.6 13.5 43.6 30.2 16.8 13.9 17.9 41.5

16.6 12.3 9.7 24.5 46.4 67.1 25.0 17.4 10.1 38.1 24.4 12.2 10.3 13.7 33.8

16.6 12.3 9.7 25.8 50.2 71.4 26.3 19.6 10.8 40.9 27.7 14.5 10.3 13.7 33.8

nare posterior and

length length tip snout

length width width

Maxillary-barbel Outer mental-barbel Inner mental-barbel Head length Head depth width Head interorbital Fleshy interorbital Bony Eye diameter length Snout between Distance length Intranarial internarial Anterior Posterior internarial gape Mouth

...............

31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

on body coloration: unnumb. p.; phylogenetic relationships: unnumb. p.].

Cetopsorhamdia sp. n. 3. – Bockmann & Slobodian, 2013 [likely endemic of part of the Rio Madeira system: 19; photograph in left lateral view: 24 (UFRO-I 10968, 72.7 mm SL); distribution – Rio Machado and Roosevelt , Brazil: 25; material cited – UFRO-I 10869 (misspelled catalog number; actually UFRO-I 10968; part of lot currently at LIRP 10032): 25; brief description: 25; in key of identification of heptapterids of Rio Madeira basin: 72; in list of heptapterids report- ed to the Mamoré/Beni/Madre de Díos/Madeira system – geographic distribution; additional material (MCP 36063, MCP 36064): 74, unnumb. tab.]; Ohara & Lima, 2015 [ecological notes of the collecting site – Brazil, Rondônia, Vilhena, rio Madeira basin, upper rio Machado, tributary of igarapé Piracolina, near road BR-364, 12°48′56.5″S, 60°06′37.6″W – UFRO-I 22918: 566]; Ohara & Marinho, 2016 [ecological notes of the collecting site – Brazil, Rondônia, Vilhena, rio Madeira basin, upper rio Machado, tributary of igarapé Piracolina, near road BR-364, 12°48′56.5″S, 60°06′37.6″W – UFRO-I 22918: 41]; Ohara et al., 2016 [ecological notes of the collecting site – Brazil, Rondônia, Vilhena, rio Madeira basin, upper rio Machado, tributary of igarapé Piracolina, near road BR-364, 12°48′56″S, 60°06′37″W – UFRO-I 22918: 547].

Undescribed species of Cetopsorhamdia . – Ohara et al., 2016 [endemic to the Rio Madeira basin: 549].

Holotype: MCP 36064, 50.8 mm SL in ethyl alcohol (ms and xr), Brazil, Rondônia State, Vilhena, Igarapé Piracolina, Rio Ji-Paraná (or Machado) basin, Rio Madeira drainage, ca. 6 km W of Vilhena, near highway BR- 364, at Chapada dos Parecis, 12°43′33″S, 60°11′34″W, coll. R.E. Reis, P.A. Buckup, A.R. Cardoso, E.H.L. Pereira, 14 Jul 2004.

Paratypes: All specimens from Brazil, Rondônia State, Vilhena: ANSP 188921, 2 ex. in ethyl alcohol (21.3-55.0 mm SL, ms and xr), collected with holotype; LIRP 10032 (ex UFRO-I 10968), 2 ex. in ethyl alcohol (35.5-40.1 m SL, ms and xr), unnamed igarapé affluent of Rio Roosevelt , Rio Madeira drainage, at Chapada dos Parecis, 12°24′33.6″S, 59°58′31.5″W, coll. Laboratório de Ictiologia e Pesca/UNIR team, 4 Sep 2011; MCP 36063, 5 ex. in ethyl alcohol (20.3-27.8 mm SL, all ms and xr), 1 ex. c&s (49.2 mm SL); MNRJ 35877, 1 ex. in ethyl alcohol (40.9 mm SL, ms and xr), collected with holotype; MZUSP 115512, 9 ex. in ethyl alcohol (15.5-52.4 mm SL), unnamed igarapé affluent of Igarapé Piracolina, Rio Ji-Paraná (or Machado) basin, Rio Madeira drainage, ca. 3 km from the border between the states of Mato Grosso and Rondônia, at Chapada dos Parecis, 12°48′58″S, 60°06′43″W, coll. W.M. Ohara, 3 Sep 2014; MZUSP 117063, 1 ex. in ethyl alcohol (31.0 mm SL), unnamed igarapé affluent of Igarapé Piracolina, Rio Ji- Paraná (or Machado) basin, Rio Madeira drainage, at Chapada dos Parecis, 12°48′58″S, 60°06′43″W, coll. W.M. Ohara, 12 Nov 2014; UFRO-I 10968, 1 ex. in ethyl alcohol (72.7 mm SL,ms and xr), same data as LIRP 10032; UFRO-I 10979, 2 ex. in ethyl alcohol (24.7-53.9 mm SL, ms and xr), unnamed igarapé affluent of Rio Ji-Paraná (or Machado), Rio Madeira drainage, near Vilhena, towards Porto Velho, at Chapada dos Parecis, 12°42′54.1″S, 60°21′35.6″W, coll. Laboratório de Ictiologia e Pesca/UNIR team, 3 Sep 2011; UFRO-I 22918, 12 ex. in ethyl alcohol (21.7-34.0 mm SL), unnamed igarapé affluent of Igarapé Piracolina, Rio Ji- Paraná (or Machado) basin, Rio Madeira drainage, at Chapada dos Parecis, 12°48′56.5″S, 60°06′37.6″W, coll. W.M.Ohara,D.B. Hungria, B.S.Barros, 14 Sep 2013;UFRO-I 22921, 1 ex. in ethyl alcohol (61.2 mm SL, ms and xr), unnamed igarapé affluent of Igarapé Piracolina, Rio Ji- Paraná (or Machado) basin, Rio Madeira drainage, at Chapada dos Parecis, 12°40′04″S, 60°15′58″W, 29 July 2013, coll. I.D. Costa; UFRO-I 23004, 1 ex. in ethyl alcohol (28.3 m SL, ms and xr), unnamed stream affluent of Igarapé Piracolina, where crossed by highway BR- 364, in the road next to the telecom tower, at Chapada dos Parecis, 12°40′51″S, 60°13′36.9″W, coll. Laboratório de Ictiologia e Pesca/UNIR team, 14 Sep 2013.

Diagnosis

Cetopsorhamdia clathrata differs from its congeners, and all other heptapterids, by a unique color pattern of trunk constituted by two longitudinal rows of 10-12 quadrangular marks which gives the fish a crisscross appearance (evident in specimens 27.8 mm SL and larger). Such a color pattern is produced by two presumably independent features: 9-11 transverse bars of interrupted pigmentation and an unpigmented stripe along the midlateral portion of trunk (vs. body homogeneously darkly pigmented or with different color pattern). Specimens of all sizes of C. clathrata are further distinguished from other species of Cetopsorhamdia by possessing a higher number of vertebrae, 40-42, usually 41 (vs. 37 in C. boquillae ; 37-39, usually 37-38, in C. iheringi ; 35-38, usually 36-37 in C. insidiosa , C. nasus , and C. picklei ; 39-40 in C. spilopleura ). It can be distinguished from most species of Cetopsorhamdia , except C. spilopleura , by having: very short maxillary barbel, not reaching posterior margin of opercle in specimens 22.4 mm SL or longer (vs. reaching the first third of pectoral fin in C. insidosa and C. nasus ; reaching the second third of pectoral fin in C.iheringi and C. picklei ; and surpassing the posterior margin of pectoral fin in C. boquillae ); dorsal fin more posteriorly located, with first basal radial articulated with the bifid dorsal process of vertebrae 11-12 (vs. 8-9 in C. boquillae , C. iheringi , C.insidiosa , C.nasus , and C. picklei ); anal fin situated more posteriorly, with its first basal radial normally articulated between hemal spines of vertebrae 23-25 (vs. 21-22 in C. boquillae and C. insidiosa , 21-23 in C. iheringi and C. nasus ; and 20-23, usually 20-22, in C. picklei ); and whitish ovoid areas on both caudal-fin lobes (vs. caudal fin lobes homogeneously dark in other species). Cetopsorhamdia clathrata is further distinguished from C. spilopleura by having fins narrow, with marked concave posterior margins (vs. fins broad,with convex posterior profiles); a long and complete lateral line, extending to slightly beyond the caudal-fin base (vs. lateral line fragmented as isolated patches behind the level of the adipose-fin origin, reaching the level of the anterior portion of the caudal plate); and the laterodorsal and lateroventral regions of the trunk with continuous dark pigmentation (not forming two unpigmented lateral streaks), except for the intervals between the squares (vs. laterodorsal and lateroventral regions of trunk devoid of dark pigmentation).

Description

Morphometrics of holotype and some paratypes in Table 1. See Figs. 1-4 for general body shape. Body relatively elongated, its cross-section oval predorsally, becoming gradually more compressed caudally. Anterior dorsal profile of body gently convex, with sometimes discrete hump at posterior limit of head. Dorsal profile of head gently convex, continuous with dorsal profile of trunk. Dorsal profile of trunk posterior to dorsal-fin base approximately straight to base of caudal fin. Ventral profile of head approximately straight and continuous with abdominal region. Ventral trunk contour slightly convex or straight from pelvic-fin origin to end of anal-fin base, and straight to base of caudal fin. Posterior body depth gradually decreasing caudally. Axillary pore minute, just dorsal to pectoral-fin base, and ventral to first pore of lateral line. Urogenital and anal openings adjacent to each other; anal opening approximately on vertical through middle of pelvic fin.

Head longer than broad, depressed, and subtriangular to trapezoidal in dorsal view ( Figs. 1-5 ). Anterior and posterior cranial fontanels short, separated from each other by broad bridge, about two times longer than each fontanel ( Fig. 6B ). Eye small, laterodorsally located, approximately equidistant from snout tip and supraoccipital end, and without free orbital rim except for shallow ventral invagination. Deep longitudinal facial ridge marking dorsal limit of adductor mandibulae muscle, extending from dorsal base of maxillary barbel to or just anterior of eye. Cheek distinctly swollen below eye forming groove to maxillary barbel. Anterior intranarial width and posterior intranarial width approximately equal. Anterior and posterior nares far apart from each other; internarial length slightly greater than distance between each pair of nares. Anterior naris surrounded by fleshy tubular flap of integument, with anterior margin slightly raised. Base of anterior nostril shallow, not sunk in conspicuous trench. Posterior naris wide, elliptical, with transversal axis longest. Posterior naris surrounded by low fleshy flap anteriorly, mesially and laterally; posterior margin devoid of flap. Mouth distinctly subinferior; gape gently convex anteriorly, slightly downturned at corners. Skin of lips with fleshy rictal fold at corner of gape. Rictal fold ventrally subtended by submandibular groove that extends anteriorly to point approximately adjacent to third or fourth preoperculomandibular pores (pm3 and pm4, respectively).

Premaxilla with 8-9 and dentary with 4-5 irregular rows of small, villiform teeth ( Fig. 6C ). Anteriormost tooth row of premaxilla with 15-18 teeth; anteriormost tooth row of dentary with 23-26 teeth. Palate and vomer edentulous.

Gular fold distinct, fleshy, and broadly V-shaped. Branchiostegal membranes well-developed, free, united to isthmus only at medial apex, and not connected to each other anteriorly ( Fig. 5C ). Branchiostegal rays 8 (13*) or 9 (4), posteriormost two wider and more laminar than anterior ones ( Fig. 7 ). Ceratobranchials 1-2, and 5 with rakers along lateral margin only; ceratobranchials 3-4 with rakers along both lateral and mesial margins ( Fig. 8 ). Branchial rakers short and straight, 6/6 (4), 6/7 (2), 7/6 (1), 7/7 (9*), or 8/8 (1) on first ceratobranchial (including one on angle formed with epibranchial), and 0/0 (16*) or 1/0 (1) on first epibranchial.

Barbels relatively short and flattened dorso-ventrally, and progressively tapering distally ( Figs. 1-5 ). Tip of maxillary barbel barely reaching posterior limit of opercle and rarely surpassing posterior margin of branchiostegal membrane (only in 22.1 mm SL or smaller specimens), when adpressed against body. Outer mental barbel longer than inner barbel. Inner and outer mental barbels inserted at approximately same line. Tip of outer mental barbel slightly beyond posterior border of branchiostegal membrane when parallel to main body axis, sometimes reaching level of pectoral-fin base, in 40.9 mm SL or smaller specimens; barely reaching posterior border of branchiostegal membrane of 50.8 mm SL or larger specimens. Tip of inner mental barbel slightly beyond to just reaching posterior border of branchiostegal membrane when papallel to main body axis in 27.8 mm SL or smaller specimens; barely reaching posterior border of branchiostegal membrane of specimens 50.8 mm SL or larger.

Dorsal fin approximately triangular in lateral profile, not reaching to adipose fin when adpressed ( Figs. 1-3 ). Dorsal fin with i,6 (17*) rays. First dorsal-fin ray (spinel- et) absent. Second dorsal-fin ray unbranched, with basal third stiffened and unsegmented and distal two thirds flexible and segmented. Second dorsal-fin ray slightly shorter than third and fourth rays (first and second branched rays, respectively). Origin of dorsal fin slightly anterior to vertical through pelvic-fin origin. Dorsal fin with 7 (17*) basal radials. Anteriormost dorsal-fin basal radial on neural spine of vertebra 11 (3), on space between neural spines of vertebrae 11 and 12 (2), or on neural spine of vertebra 12 (12*).Posteriormost dorsal-fin basal radial on space between neural spines of vertebrae 15 and 16 (10), on neural spine of vertebra 16 (3), or between neural spines of vertebrae 16 and 17 (4*).

Pectoral fin with distal margin straight to slightly convex ( Figs. 1-4 ), with i,7 (2) or i,8 (15*) rays. First pectoral-fin ray with basal third rigid and unsegmented and distal two thirds flexible and segmented ( Fig. 9 ). First pectoral-fin ray slightly shorter than second (first branched) and third (second branched) rays, whose tips project slightly beyond tip of first ray. Pectoral fin lying parallel to main body axis when expanded and slightly directed upwards when adpressed to body.

Pelvic fin wide, with distal border straight to slightly rounded ( Figs. 1-3 ), with i,5 (17*) rays. Origin of pelvic-fin base slightly posterior to vertical through dorsal-fin origin, on vertical through space between insertions of first (unbranched) and second (first branched) dorsal-fin rays (8*), or on vertical through insertion of second (first branched) dorsal-fin ray (9). Inner margins of pelvic-fin bases apart from each other. Tip of adpressed pelvic fin falling at mid distance between pelvic- and anal-fin origins. Lateralmost ray unbranched, completely flexible, segmented, and with tip distinctly falling short of tips of second and third rays (first and second branched rays,respectively).Origin of pelvic fin on vertical through region between centra 13 and 14 (1), on vertical through vertebral centrum 14 (5), on vertical through region between centra 14 and 15 (7), or on vertical through vertebral centrum 15 (4*).

Anal fin deeper than adipose fin, with short base and distal border slightly rounded ( Figs. 1-3 ), with 12 (9*), 13 (7), or 14 (1) total rays, including 7 (3), 8 (12*), or 9 (2) branched rays. Anal-fin rays with following branching pattern: iv,8 (6*), iv,9 (2), v,7 (3), or v,8 (6). Two anteriormost anal-fin rays vestigial, unsegmented, embedded into thick anterior fold. Origin of anal-fin base just anterior to vertical through origin of adipose fin. End of anal-fin base at or slightly posterior to vertical through middle of adipose-fin base. Anal fin with 10 (10), 11 (6*), or 12 (1) basal radials. Anteriormost anal-fin basal radial on space between hemal spines of vertebrae 22 and 23 (3), on space between hemal spines of vertebrae 23 and 24 (10), or on space between hemal spines of vertebrae 24 and 25 (4*). Posteriormost anal-fin basal radial on space between hemal spines of vertebrae 28 and 29 (9*), on space between hemal spines of vertebrae 29 and 30 (7), or on space between hemal spines of vertebrae 30 and 31 (1).

Adipose fin moderately deep and short, highest approximately at midpoint ( Figs. 1-3 ). Adipose fin merging gradually with back anteriorly, with imprecise origin. Distance from dorsal-fin base to adipose fin approximately twice length of dorsal-fin base. Origin of adipose fin slightly posterior to origin of anal fin, on vertical through insertion of last unbranched anal-fin ray (5), on vertical through insertion of first branched anal-fin ray (9), or second branched anal-fin ray (2*). Posterior limit of adipose fin well-defined, with distinct free, rounded lobe.Vertical through end of adipose-fin base at or slightly posterior to tip of posteriormost anal-fin ray. Origin of adipose fin on vertical through vertebral centrum 26 (5), on vertical through region between centra 26 and 27 (3), on vertical through vertebral centrum 27 (7), or on vertical through region between centra 27 and 28 (2*). End of adipose-fin base on vertical through vertebral centrum 34 (1), on vertical through region between centra 34 and 35 (4), on vertical through vertebral centrum 35 (9*), on vertical through region between centra 35 and 36 (2), or on vertical through centrum 36 (1).

Caudal fin forked, with ventral lobe longer than dorsal lobe ( Figs.1-3 ). Dorsal lobe with 7 (17*) branched rays; ventral lobe with 8 (16*) branched rays, rarely 7 (1). Total caudal fin-rays 39 (1), 40 (1), 41 (4), 42 (1), 43 (2), 44 (5*), 45 (1), 46 (1), or 47 (1), being 18 (1), 20 (6), 21 (4*), 22 (4), or 23 (2) rays in dorsal lobe, and 20 (1), 21 (6), 22 (4), 23 (5*), or 24 (1) rays in ventral lobe. Dorsal caudal plate (uroneural and hypurals 3, 4, and 5) with 8 (17*) rays, arranged as follows:6 rays on hypural 3+4 and 2 rays on hypural 5 (16*), or 8 rays on hypural 3+4+5 (1). Ventral caudal plate (parhypural plus hypurals 1 and 2) with 8 (16*), rarely 9 (1) rays, arranged as follows: 1 ray on parhypural and 7 rays on hypural 1+2 (6), 2 rays on parhypural and 6 rays on hypural 1+2 (9*), 8 rays on parhypural + hypural 1+2 (1), or 2 rays on parhypural and 7 rays on hypural 1+2 (1).

Number of vertebrae 40 (6), 41 (10*) or 42 (1); first completely formed hemal spine on centrum 16 (6) or 17 (11*); and ribs 8/8 (10) or 9/9 (7*). Last four (4*), five (7), or six (6) precaudal vertebrae with discrete neural processes. Last precaudal vertebra (1), or last two (5), three (6), or four (5*) precaudal vertebrae with very discrete, almost imperceptible, neural processes.

Figures

Figure 1.Cetopsorhamdiaclathrata,MCP 36064,50.8mm SL,holotype;Brazil,Rondônia State,Vilhena:Igarapé Piracolina,RioMadeirabasin,at Chapadados Parecis.

Figure 2. Cetopsorhamdia clathrata, UFRO-I 10979, 53.9 mm SL,paratype (right after collection);Brazil,Rondônia State,Vilhena: unnamed igarapé affluent of Rio Ji-Paraná (or Machado),Rio Madeira drainage,nearVilhena,towards PortoVelho,at Chapada dos Parecis.Photograph byW.M.Ohara.

Figure 3. Developmental series of Cetopsorhamdia clathrata, lateral view,paratypes, showing ontogenetic color pattern changes; Brazil, Rondônia State,Vilhena: Igarapé Piracolina,Rio Madeira basin:MCP 36063,(A) 21.5 mm SL,(B) 22.1 mm SL,(C) 22.4 mm SL,(D) 27.8 mm SL;and MNRJ35877,(E) 40.9 mm SL.

Figure 4. Developmental series of Cetopsorhamdia clathrata, dorsal view, paratypes, showing ontogenetic color pattern changes; Brazil, Rondônia State,Vilhena: Igarapé Piracolina,Rio Madeira basin:MCP 36063,(A) 21.5 mm SL,(B) 22.1 mm SL,(C) 22.4 mm SL,(D) 27.8 mm SL;and MNRJ 35877, (E) 40.9 mm SL.

Figure 5.Anterior portion of the body of Cetopsorhamdia clathrata, ANSP 188921,55.0 mm SL,paratype,showing laterosensory canal system.(A) left lateral view; (B) dorsal view;(C) ventral view.Scale bar = 4 mm.

Figure 6. Neuroranium and associated structures of Cetopsorhamdiaclathrata, MCP 36064,50.8 mm SL,holotype (CT reconstructions).(A) leftlateral view;(B) dorsal view;(C) ventral view.Cartilage not represented.Scale bars= 2 mm.

Figure 8. Branchial arches of Cetopsorhamdia clathrata, MCP 36064, 50.8 mm SL, holotype (CT reconstruction). Dorsal view. Dorsal elements of left arches not shown.Cartilage not represented.Scale bar = 2 mm.

Figure 9. Left pectoral fin of Cetopsorhamdia clathrata, UFRO-I 10979, 53.9 mm SL,paratype (radiograph).Dorsal view.Scale bar = 3 mm.

Figure7. Hyoid archesofCetopsorhamdiaclathrata, MCP36064,50.8 mmSL, holotype (CT reconstruction). Ventral view. Cartilage not represented. Scale bar = 2 mm.