Tympanopleura cryptica, Walsh & Ribeiro & Py-Daniel, 2015

Walsh, Stephen J., Ribeiro, Frank Raynner Vasconcelos & Py-Daniel, Lúcia Helena Rapp, 2015, Revision of Tympanopleura Eigenmann (Siluriformes: Auchenipteridae) with description of two new species, Neotropical Ichthyology (Neotrop. Ichthyol.) 13 (1), pp. 1-46 : 24-28

Tympanopleura cryptica , new species urn:lsid:zoobank.org:act:BF66586A-0B47-47CE-B812-5B7B809D3430

Figs. 1c , 6d , 13

Holotype. MUSM 47102 (ex INHS 40163 ), 84.9 mm SL, prenuptial male, Peru, Loreto, río Solimões drainage, río Orosa, mouth of Tonche Cano , 69.4 mi E of Iquitos c. 3°47’26”S 73°14’50”W, 12-13 August 1996, M.H. Sabaj Pérez, J.W. Armbruster & M. Hardman.

Paratypes. 40 specimens (54.1-78.2 mm SL). Brazil. Amazonas : INPA 12609 , 1 (67.5 mm SL), Ilha da Marchantaria, Lago Camaleão , 4 Feb 1981 , INPA ichthyology team; INPA 18986 , 1 (66.9 mm SL), Tefé, rio Japurá, margin of Mamirauá Sustainable Development Reserve , 19 Jan 1999, W.G . R. Crampton; INPA 25112 , 1 (78.2 mm SL), rio Madeira, Cachoeirinha , 19 Sep 2004, D. Pimpão ; INPA 35926 , 4 (54.1-72.0 mm SL, 1 c/s), rio Purus, Lago Samaúma, tributary of rio Abufari , Berurí , 8 Dec 2000, L.H. Rapp Py-Daniel et al . Peru. Loreto: ANSP 139065 , 1 (59.0 mm SL), vicinity of Iquitos, río Nanay opposite naval base, backwater pools 1 & 2, above Amazon , 12 Oct 1955, C.G. Chaplin et al. (Catherwood Expedition) ; ANSP 194024 , 2 (65.5-66.0 mm SL), collected with holotype ; CAS 158750 , 1 (63.0 mm SL), Yahnas Yacu, proximity of Pevas (= Pebas ), 24 Jul 1941, W.G. Scherer ; INHS 40163 , 15 (56.2-67.1 mm SL), collected with holotype ; INHS 44032 , 1 (67.6 mm SL), río Nanay, Pampa Chica 4.54 km W center of Iquitos c. 3°45’8.8”S 73°17’0.1”W, 22 Jul 1997, M.H. Sabaj Pérez & J.W. Armbruster ; INHS 44198 , 1 (68.3 mm SL), río Nanay upriver from Santa Clara at Mizplaya , 13.9 km W of Iquitos c. 3°46’54.6”S 73°21’49.6”W, 29-30 Jul 1997, M.H. Sabaj Pérez et al .; MHNG 2394.39 , 3 (56.5- 61.0 mm SL), río Calleria, vers. Embouchure, dans le río Ucayali Cocha Tachsitea , 3 Oct 1984, P. de Rham & H. Ortega ; MUSM 47103 , 3 (62.6-65.8 mm SL), collected with holotype ; MZUSP 115005 , 2 (60.9-64.5 mm SL), collected with holotype ; UF 185771 , 2 (62.3-67.3 mm SL), collected with holotype ; USNM 270812 , 2 (56.4-72.2 mm SL), río Ucayali, Pucallpa, Tacshitea , 3 Oct 1984, H. Ortega .

Non-type material. 3 specimens (35.0- 39.5 mm SL). Peru. Loreto: UF 128851 , 1 (39.5 mm SL), Caño Yarina, río Pacaya in Reserva Nacional Pacay Samiria c. 5°17’39.5”S 74°29’53.1”W, 12 May 2003, J.S. Albert & W.G. R. Crampton; UF 129190 , 2 (35.0-37.0 mm SL), same general locality as UF 128851 c. 5°24’37.3”S 74°30’15.18”W, 14 May 2003, J.S. Albert & W.G. R. Crampton .

Diagnosis. Tympanopleura cryptica is distinguished from congeners on the basis of a unique combination of characters. Tympanopleura cryptica differs from T. atronasus in having more gill rakers on the first arch (21- 26, mode 22 vs. 14-23, mode 16), fewer preanal vertebrae (14-15 vs. 16-19), fewer total vertebrae (38-41, mode 38 vs. 39-43, mode 41), fewer pleural rib pairs (4-5 vs. 7-8), greater distance between pectoral- and dorsal-fin origin (21.6-24.3% SL vs. 15.7-20.9% SL), and a uniform body coloration that does not include a dark blotch of melanophores on the flank above the anal-fin base or streaks in the caudal fin, as is typically present in T. atronasus . Tympanopleura cryptica differs from T. brevis in having fewer anal-fin rays (23-30 vs. 31-36), fewer pectoral-fin rays (8-10, mode 9 vs. 10-12, mode 11), and fewer total vertebrae (38 vs. 38-41,mode40). Tympanopleura cryptica differs from T. longipinna in having fewer anal-fin rays (23-30 vs. 32-42), fewer pectoral-fin rays (8-10, mode 9 vs. 10-13, mode 11), more preanal vertebrae (14-15, mode 15 vs. 13-15, mode 14), fewer total vertebrae (38-41, mode 38 vs. 40-43, mode 43), greater preanal length (59.6-66.0% SL vs. 49.7-57.6% SL), shorter distance between dorsal- and adipose-fin origin (33.9-46.7% SL vs. 46.5-54.0% SL), shorter anal-fin base (24.4-30.3% SL vs. 33.9-39.9% SL), and a slightly larger eye diameter (16.7-25.6% HL vs. 11.6-18.5% HL). Tympanopleura cryptica differs from T. piperata in having fewer anal-fin rays (23-30 vs. 31-38), more gill rakers on the first arch (21-26, mode 22 vs. 16- 23, mode 19), fewer total vertebrae (38-41, mode 38 vs. 39-41, mode 40), greater prepelvic length (48.4-53.6% SL vs. 41.3-47.0% SL), greater prepectoral length (29.7-33.8% SL vs. 23.6-28.3% SL), greater distance between pectoral- and dorsal-fin origin (21.6-24.3% SL vs. 15.2-20.9% SL), shorter distance between dorsal- and adipose-fin origin (33.9-46.7% SL vs. 45.9-55.4% SL), shorter anal-fin base (24.4-30.3% SL vs. 30.9-39.3% SL), a slightly smaller eye diameter (16.7-25.6% HL vs. 24.3-35.7% HL), presence of two small posterior diverticula on gas bladder (vs. diverticula absent), and base of the caudal fin without a characteristic dark, hourglass-shaped transverse bar usually present in T. piperata . Tympanopleura cryptica differs from T. rondoni in having fewer anal-fin rays (23- 30, mode 29 vs. 28-37, mode 31), fewer pectoral-fin rays (8-10, mode 9 vs. 10-13, mode 11), fewer gill rakers on the first arch (21-26, mode 22 vs. 24-33, mode 29-30), fewer total vertebrae (38-41, mode 38 vs. 38-42, mode 40), fewer pleural rib pairs (4-5, mode 5 vs. 4-6, mode 6), a larger eye diameter (16.7-25.6% HL vs. 8.4-17.0% HL), gas bladder cordiform and with two short posterior diverticula (vs. gas bladder elongated antero-posteriorly and with two longer, recurved diverticula), and pigmentation on the head and body diffuse and relatively uniform in appearance, in contrast to the prominent spotted pattern of T. rondoni .

Description. Tympanopleura cryptica is a small-sized auchenipterid. Specimens of undetermined sex, mature females, and non-nuptial males ranged in size from 35.0- 78.2 mm SL (n=29). Prenuptial and nuptial males ranged in size from 57.5-84.9 mm SL (n=15). Morphometric data are summarized in Table 10. Dorsal profile of head nearly straight or weakly convex to dorsal-fin origin. Dorsal profile of body from behind dorsal fin to caudal fin slightly convex to nearly straight. Body relatively short, depth at base of dorsal fin approximately equal to or slightly greater than body width at origin of pectoral fin. Ventral profile of head flat, ventral profile of body from isthmus to anal-fin origin straight or gently rounded, angled upward posteriorly along anal-fin base. Caudal peduncle deep, 8.3-11.4% SL. Body not markedly compressed at pectoral- or pelvic-fin base, but rather gradually tapered to base of caudal fin.

Head length 25.9-33.0% SL. Mouth only weakly inferior, upper jaw projecting anterior to tip of lower jaw a distance approximately equal to width of the premaxillary tooth band and less than half of eye diameter. Corners of mouth approximately in line with transverse plane extending between posterior nares; posterior edge of lower jaw extending to a point approaching a plane through middle of the eye. Snout short, 40.4-51.3% HL, forming a broad arc or squared off in dorsal and ventral view. Jaw teeth small, conical, slightly recurved, barely extending through epidermal tissue. Center of premaxillary tooth plate partially to fully exposed in ventral view, fully exposed posterolaterally, with about 3-6 irregular rows of teeth at midline, tapering to 1-2 rows posterolaterally. Dentary teeth small, thin, conical, distributed in about 3-4 uneven rows and slightly exposed laterally. Eye relatively large, horizontal diameter 16.7-25.6% HL, covered by thick epidermis; eyes lateral, equally visible in dorsal and ventral view ( Fig. 1c ). Cranial fontanelle relatively elongate, open from posterior margin of mesethmoid along anteromedial half of frontals to a point just anterior to a plane passing through posterior margins of the eyes. Anterior nares lateral to distal tips of mesethmoid wings and directed anterodorsally; posterior nares remote, about equidistant between anterior nares and anterior margin of orbit, encircled by short ridge of epidermis. Gill membranes broadly fused to isthmus along a plane falling posterior to rear margin of orbit, pre-isthmus length about 62.5-82.8% HL. Branchiostegal rays 7-8 (mode 8; n=19). Total gill rakers on anterolateral margin of first arch 21- 26 (mode 22; n=23); first epibranchial with 6-10 (mode 8) and first ceratobranchial with 13-20 (mode 14) gill rakers. Longest gill rakers near middle of arch thin and crenulate on medial margin; tapering, short, and pointed near distal ends of each arch.

Maxillary barbel of females and non-nuptial males small, filamentous, concealed in premaxillary groove, length 13.9-15.8% HL (mean=15.1±0.8 SD; n=6). Maxillary barbel of prenuptial males ossified and slightly thickened over approximately proximal one-half to three-fourths, with fleshy terminus, extending slightly beyond rictus, lacking well-developed hooks, length 21.2-29.6% HL (mean=24.1±2.7 SD; n=11). Structure of nuptial male maxillary barbel unknown, as no peak nuptial males were available in material examined.

Dorsal fin rays II,6, consisting of a small spinelet, elongated spine, and branched rays; first ray longest, extending anterior to or about equal to midpoint between dorsal-fin origin and adipose-fin origin when fin is adpressed. Dorsal-fin spine short, relatively thin and weak in females and non-nuptial males, depressed spine reaching less than midpoint between dorsal-fin origin and adipose-fin origin, length of spine 16.8-22.3% SL (mean=20.2±1.6 SD; n=10). Dorsal-fin spine elongated in prenuptial and nuptial males, 18.6-34.9% SL (mean=23.5±4.6 SD; n=13). Serration of spine variable. In females and non-nuptial males, anterior margin of spine weakly to strongly crenulated with single row of low-crowned serrae (range 12-33; mean=22.9±6.1 SD; n=15), crowded together proximally and forming a low embedded keel, more distantly separated distally, or absent altogether over distal half or more. Dorsal, ventral, and lateral margins of spine with well developed longitudinal grooves and ridges. Posterior margin of spine in females and non-nuptial males with 13-24 weak serrae (mode 20; mean=18.7±3.0 SD; n=18); serrae short, relatively blunt, absent near base, displaced to ventrolateral edge of spine in some specimens, and occasionally nearly absent on entire posterior margin. Detailed structure of dorsal-fin spine of nuptial males unknown; one prenuptial male examined (USNM 270812; 72.2 mm SL) with entire anterior margin of dorsal-fin spine crenulated, denticulations longest and most closely spaced proximally, but lacking well developed serrae; posterior margin weakly crenulated proximally and smooth distally. Longest dorsal-fin rays reaching well beyond tip of spine in all but prenuptial and nuptial males. Adipose fin small, posterior margin free.

Anal fin relatively short, base 24.4-30.3% SL, with 23-30 rays (mode 29; n=39); distal margin gently convex in juveniles, females, and non-nuptial males. Anal-fin pterygiophores 25-28 (mode 27; n=25) in specimens examined with ≥ 27 anal rays. First 5 anal-fin rays of prenuptial males unbranched, elongated, and thickened to form intromittent organ; gonopore located distally on leading edge of anal fin about one-third to one-half distance from base to tip of longest ray, presumably displaced toward distal end in fully nuptial male.

Pectoral-fin spine well developed, relatively short, stout, 14.2-22.7% SL, not reaching to pelvic-fin origin. Anterior margin nearly smooth or weakly rugose proximally, lacking distinct serrae. Dorsal and ventral surfaces of spine with shallow longitudinal grooves. Posterior margin of spine with single series of retrorse serrae along entire length except short proximal section; serrae range from 16-25 (mode 18; mean=17.7±1.7 SD; n=22). Pectoral fin with 9-10 (mode 9; n =38) branched rays; anterior-most pectoral rays longest. Postcleithral process typically present, short, conical.

N Range Mean SD Holotype MUSM 47102 Standard length (SL, mm) 26 56.4-78.2 --- --- 84.9

Percent of SL

Preadipose length 19 78.6-82.9 80.9 1.1 80.9

Preanal length 26 59.6-66.0 62.5 1.4 63.7 Predorsal length 26 31.9-41.6 37.1 2.1 37.3 Prepelvic length 26 48.3-53.6 50.5 1.2 51.6 Prepectoral length 20 29.7-33.8 30.9 1.0 29.7 Pectoral-fin origin to dorsal-fin origin 20 21.6-24.3 23.3 0.7 21.6 Pelvic-fin origin to dorsal-fin origin 20 23.0-28.2 25.8 1.2 26.1 Pelvic-fin origin to adipose-fin origin 25 18.7-39.7 33.2 6.2 36.0 Dorsal-fin origin to adipose-fin origin 26 33.9-46.7 43.0 3.7 45.2 Adipose-fin origin to anal-fin insertion 20 12.9-15.6 14.8 0.6 15.4

Body depth at dorsal-fin origin 26 17.8-24.2 22.7 1.7 22.1

Caudal peduncle depth 26 8.3-11.4 10.6 0.7 10.2

Caudal peduncle length 26 10.5-14.7 12.6 1.1 11.2

Body width at pectoral-fin origin 26 15.9-25.0 21.8 2.9 22.6

Body width at pelvic-fin origin 20 9.5-13.2 11.7 0.8 11.9

Pectoral spine length 25 14.2-22.7 19.7 2.2 19.6

Anal-fin base length 26 24.4-30.3 27.7 1.3 27.4

Head length (HL) 26 25.9-33.0 29.8 2.0 29.4

Percent of HL

Head depth at supraoccipital 25 47.7-68.6 58.6 4.0 59.6

Head width at postorbitals 26 62.8-80.6 72.1 4.7 73.6

Dorsal interopercular width 20 45.8-58.4 51.0 2.6 50.0

Anterior internarial distance 26 25.6-44.0 32.9 3.7 44.0 Preisthmus length 20 62.5-82.8 71.1 4.7 74.8

Snout length 26 40.4-51.3 44.0 2.7 47.6

Gape width 26 47.5-60.6 55.0 3.6 57.2

Upper jaw length 20 31.4-40.1 35.8 2.2 37.2

Lower jaw length 20 26.3-36.5 32.0 2.3 33.2

Eye diameter 26 16.7-25.6 20.9 2.1 19.6

Pelvic-fin origin posterior to tips of longest adpressed pectoral-fin rays; distal margin of fin straight to slightly convex. Pelvic fin rays i,6; first branched ray longest, subsequent rays progressively shorter.

Caudal fin forked, lobes equal, with 8+9 principal rays, 17-22 (mode 19; n=12) upper, and 13-15 (mode 15) lower procurrent rays.

Preanal vertebrae 14-15 (mode 15; n=32). Total vertebrae 38-41 (mode 38; n=32). Pairs of pleural ribs 4-5 (mode 5; n=17). Little variation was observed in vertebral and rib counts in the material examined, with very few specimens having counts different than the modes ( Tables 4-6).

Gas bladder of adults large, cordiform, posterior margin blunt, tunica smooth and thin over dorsal, lateral, and anteroventral surfaces. Exterior posteroventral surface of tunica thickened, with weak, irregular, posterolaterally radiating ridges as in T. piperata . Two short terminal diverticula joined or weakly proximate at their bases ( Fig. 6d ).

Color in alcohol. Base color of head and body dark brown, gray, or tan with pigmentation generally of relatively uniform shading. Top and sides of head, dorsum, upper half of sides of body with dense pigmentation consisting of small brown to black melanophores, darkest on head, anterolaterally, and dorsally. Pigment on sides of head extends anterior to eye, on membrane over eye, and on opercular skin slightly posteroventrally to eye. Lower half of sides of body with pigment less intense, but extending to base of anal fin and most concentrated anteriorly, especially over pseudotymanum and above pectoral-fin base. Pigment never appearing mottled or spotted. Chin in some specimens with an intense crescent or half-moon shaped patch of dark, concentrated brown melanophores, similar to T. atronasus . Streaks of brown pigment in dorsal and pectoral fins, most intense along leading edge of anterior-most ray; dorsal-fin spine and pectoral-fin spines with flecks scattered along anterior and lateral margins in the former, and anterior and top margins in the latter. Brown pigment extending from sides of body onto base of caudal fin, forming a broad, weakly defined vertical patch, somewhat darker and slightly crescent shaped in upper lobe. Adipose fin with melanophores scattered throughout. Anal and pelvic fins generally hyaline, but the latter with a small patch of melanophores above base of the anterior rays.

Distribution. Tympanopleura cryptica is known from relatively few records in the middle and upper Amazon River basin, State of Amazonas in Brazil and the Loreto Region of Peru ( Fig. 12 ).

Etymology. The specific epithet cryptica is derived from the transliterated Greek kryptos, meaning hidden or concealed, in reference to the close morphological and pigmentation similarities of this species to congeners and its previously unrecognized taxonomic distinctiveness. Gender feminine.

Figures

Fig. 1. Dorsal and ventral head profiles of species of Tympanopleura: (a) T. atronasus, INHS 106400 (82.4 mm SL); (b) T. brevis, ANSP 194010 (63.3 mm SL); (c) T. cryptica, INHS 40163 (84.9 mm SL); (d) T. longipinna, MZUSP 114000 (73.0 mm SL, holotype); (e) T. piperata, ANSP 194022 (45.6 mm SL); (f) T. rondoni, ANSP 194015 (75.3 mm SL). Scale bars: a-d, f = 1 cm; e = 5 mm.

Fig. 6. Gas bladders of species of Tympanopleura in ventral view: (a) T. atronasus, INHS 106400 (79.9 mm SL); (b) T. atronasus, FMNH 93488 (107.3 mm SL); (c) T. brevis, SIUC 39913 (59.4 mm SL); (d) T. cryptica, INHS 40163 (60.5 mm SL); (e) T. longipinna, MZUSP 34417 (50.5 mm SL); (f) T. piperata, ANSP 194019 (42.5 mm SL); (g) T. rondoni. MZUSP 7862 (117.6 mm SL). Scale bars: a-e = 5 mm; f = 2 mm; g = 10 mm.

Fig. 13. Tympanopleura cryptica, new species. (a) holotype, MUSM 47102 (84.9 mm SL), pre-nuptial male, río Orosa, Loreto Region, Peru; (b) paratype, INPA 35926 (65.3 mm SL), nuptial male, rio Purus, Amazonas State, Brazil.

Fig. 12. Distribution of Tympanopleura brevis based on material examined (squares; open square represents typelocality), T. cryptica (diamonds; open diamond represents type-locality), and both species in sympatry (open circles). Some symbols represent more than one lot or locality.