Trichomycterus iheringi (Eigenmann, 1917)

Wolmar B. Wosiacki, 2005, A new species of Trichomycterus (Siluriformes: Trichomycteridae) from south Brazil and redescription of T. iheringi (Eigenmann)., Zootaxa 1040, pp. 49-64 : 56-61

Trichomycterus iheringi (Eigenmann, 1917)

(Figs. 3, 4; Table 1)

Pygidium iheringi Eigenmann, 1917 :697 (Brazil, São Paulo). Eigenmann, 1918:330. Henn, 1928:80. Gosline, 1945:60. Ibarra & Stewart, 1987:73.

Trichomycterus iheringi - Miranda-Ribeiro, 1918:725. Fowler 1954:27. Burgess, 1989:322. Bizerril, 1994:623. de Pinna & Wosiacki, 2003:282. Costa, 1992:103. Eschmeyer, 1998:760. Barbosa & Costa, 2003:287. Bockmann & Sazima, 2004:61. Bockmann, Casatti & de Pinna, 2004:226. Triques & Vono, 2004:162. Wosiacki, 2004:9. Wosiacki & Garavello, 2004:9.

Holotype: CAS 64585 (Ex. IU 10785), 139.6mm SL, Santos, São Paulo, Brazil, collected by R. von Ihering.

Paratypes: CAS 64586, 3 ex. (117.6 128mm SL). Orig. n. IU 10785, collected with holotype; FMNH 58074, 2 ex. (125.7-134.1mm, X-rays), Sapina, São Paulo, Brazil, collected by J.D.Haseman, 23 July 1908.

Diagnosis: No uniquely derived features were found to diagnose T. iheringi . Trichomycterus iheringi shares with T. castroi , T. davisi , T. guaraquessaba , T. mboycy , T. naipi , T. papilliferus , T. plumbeus , T. stawiarski , and T. zonatus the first pectoral-fin ray not prolonged as a filament and differs from all other congeners from south and southeastern Brazil ( T. albinotatus , T. alternatus , T. auroguttatus , T. bahianus , T. brasiliensis , T. candidu , T. caudofasciatus , T. concolor , T. giganteus , T. goeldii , T. immaculatus , T. itacambirussu , T. itatiayae , T. jequitinhonhae , T. landinga , T. longibarbatus , T. maracaya , T. mimonha , T. mirissumba , T. nigricans , T. pantherinus , T. potschi , T. taroba , T. trefauti , T. reinhardti , T. triguttatus , T. variegatus , and T. vermiculatus ) by the presence of the first pectoral-fin ray prolonged as a filament. Trichomycterus iheringi shares with the larger assemblage of species congeners from south and southeastern Brazil the presence of two pores s6 paired at the interorbital space (vs. one symphyseal pore s6 in T. alternatus , T. giganteus , T. nigricans , and T. paquequerensis ). Trichomycterus iheringi shares with T. castroi , T. guaraquessaba , T. plumbeus , and T. stawiarski I-7 pectoral-fin rays (vs. I-5 in T. mboycy , T. naipi , and I-6 in T. davisi , T. papilliferus , and T. zonatus ). Trichomycterus iheringi is readily from T. castroi and T. stawiarski by the uniform light tan color pattern with numerous, poorly defined small spots over the dorsal and lateral portions of the head, trunk and caudal peduncle (vs. large and well defined spots and stripes). Furthermore, T. iheringi can be distinguished from T. guaraquessaba , T. plumbeus , and other congeners by the combination of pelvic-fin margin distance from the urogenital opening equal to half of its the fins length (vs. in contact with urogenital opening or covering it), caudal fin rounded (vs. truncate as in T. guaraquessaba ), and 9-10 branched rays in the dorsal fin (vs. 6-8).

Redescription: Morphometric data for holotype and paratypes are given in Table 1.

“T1”

Body elongate, roughly cylindrical close to head and gradually more compressed in trunk towards caudal fin. Profiles of trunk straight dorsally and slightly convex ventrally. Dorsal and ventral profiles of caudal peduncle straight. Integument thick, especially over base of dorsal and anal fins. Small papillae on lips and scattered over lateral surface of head.

Head wide, rounded and depressed, slightly longer than wide, the transversal section at posterior tip of opercle slightly wider than anteriorly at nostril, anterior margin rounded. Lateral region of eye slightly swollen by jaw muscles in both large and small specimens. Profiles of head straight dorsally and convex ventrally. Eyes rounded, well defined rim, dorsally oriented, covered by thin skin, distinctly separated from surface of eyeball. Ocular structures readily visible on surface of skin, not deeply sunken. Orbital rim not free. Anterior nostril same size as posterior one, surrounded by fleshy flap of integument. Posterior nostril with thin flap of integument anteriorly. Anterior and posterior nostrils half diameter of eye. Gill membranes thick, united to isthmus only at anteriormost point. Gill openings not constricted. Five branchiostegal rays visible externally, 7-8 in X-rayed specimens (Fig. 4). Mouth subterminal, its corners laterally oriented. Lower lip with conspicuous lateral fleshy lobes, internal to origin of rictal barbels. Anterior margin of upper lip rounded. Small papillae on external surface of upper lip; large papillae continuous inside of mouth to region of teeth attachment. Upper lip continuous with dorsal surface of head. Barbels long with large bases and gradually narrowing towards tip. Tips of nasal barbels reaching midway between posterior rim of eye and base of anterior opercular odontodes; tips of maxillary barbels reaching tip of posterior opercular odontodes; tips of rictal barbels reaching base of posterior most interopercular odontodes. Origin of nasal barbels on posterolateral portion of integument flap around anterior nostril. Interopercular patch of odontodes long, 20-22 conical odontodes covered by thick integument, anteriormost odontodes smaller and slightly curved medially, gradually longer and more curved distally. Opercular patch of odontodes rounded, covering posterior edge of opercle, 25-27 conical odontodes, anterior ones smaller and straight, gradually longer and curved distally. Supraorbital canal complete, infraorbital incomplete. Infraorbital anterior section pores i1 and i3, and posterior section pores i10 and i11. Supraorbital pores s1, s2 and s6 paired.

Pectoral fin with rounded margin, I-7 rays, first short and thickest, third and fourth longest. Dorsal-fin with margin semicircular when expanded, II-III/9-10 (Holotype, II/9) rays, fourth the longest. Anal fin slightly elongate in overall shape, slightly smaller than dorsal fin, I/5-II/5 (Holotype, II/5) rays, fourth the longest, origin at vertical through seventh dorsal-fin ray. Pelvic-fin origin anterior to dorsal-fin origin, rounded margin, not reaching anal and urogenital openings, I/4 rays, second and third longest. Caudal fin rounded, margin distinctly wider than remaining caudal region, I/11/I principal rays, branched rays splitting three times. Only the first dorsal and ventral caudal-fin accessory rays visible. Anal and urogenital openings closer to anal-fin origin than pelvic-fin base.

Free vertebrae 35. Ribs 11 pairs, first one thickest, 3rd -4th longest. Dorsal-fin pterygiophores 9, first inserting in front of the neural spines of 15th -16th free vertebrae. Anal-fin pterygiophores 6, first in front of hemal spines of 21st -22nd free vertebrae. Dorsal procurrent rays 18. Ventral procurrent rays 8. Caudal skeleton composed of pleurostyle, hypurals 4+5, hypural 3, and fused parhypural and hypurals 1+2 (Fig. 4).

Color pattern: Refer to figure 2 for general view of color pattern in alcohol. The pattern is the same for smaller (117.6 mm SL) to larger (139.6 mm SL) specimens. Uniform light tan on dorsal surface of trunk, gradually lighter laterally. Numerous, poorly defined spots over dorsal and lateral portions of head, trunk and caudal peduncle. Spots coalescent over head at the occipital and interorbital space. Spots larger at dorsal trunk and caudal peduncle, gradually less numerous and smaller ventrally. Nasal, maxillary and rictal barbels unpigmented. Ventral surfaces of head, trunk and caudal peduncle unpigmented. Pectoral fin with few small spots over dorsal surface scattered from base to half of its length. Pelvic fins unpigmented. Dorsal fin with few small spots scattered from base to half of its length rays. Caudal fin with few spots over rays, larger and closer each other at base, gradually smaller and scattered to margin.

Distribution: Known from the type-locality, Santos, on the costal area of São Paulo State, and headwaters of rio Tietê ( Paraná basin), southeastern Brazil. The Sapina locality cited by Eigenmann (1917 and 1918) for the paratypes was not located. However, Eigenmann (1911) cited “Sapina, Rio Tieté, into Paraná. Coll. Nos. 1599-1616. Four miles from the city, July 23, 1908 ”, for the Paratypes. In the same paper, cited “Santos, coast of São Paulo. July 23, 1908 ” [no July 3, 1908 in Eigenmann, 1918] for the Holotype. It is assumed that Sapina is a locality on the headwaters of rio Tietê, close to Santos.

Remarks: The present redescription of Trichomycterus iheringi was based on type material of the CAS and FMNH. The holotype and paratypes were in a good state of preservation (Fig. 2), with the color pattern slightly pale. Eigenmann (1917) presented T. iheringi in a short description based on six specimens which was adequate at the time, but incomplete by current standards. In the next year Eigenmann (1918; PL.50: 5) presented a transcription of the original description, with a very sharp drawing of the type. Eigenmann (1917, 1918), with no justification, allied T. iheringi to T. punctatissimus Castelnau , from the rio Araguaia (Tocantins basin). Eigenmann (1918; PL. 45: 1) presented a cartoonish drawing of T. punctatissimus from Castelnau (1855), and a short text of the characters in the key of that paper (“Sides and back with minute dark specks and vermiculations between them; origin of dorsal over origin of ventral”). It was not possible to analyze the type material of T. punctatissimus , and the original description (Castelnau, 1855) does not offer features to support the relationships of this species to T. iheringi . Only the color pattern cited by Castelnau (1855) for T. punctatissimus (“sa couleur générale dun châtain clair. Il est entiérement couvert de très petits point dun brun obscure très serrés et couvrant les nageoires supérieures. Le dessous du corps et les nageoires inferieures sont dun brun jaune”), cited by Eigenmann (1918) suggests some similarity to T. iheringi . However, the presence of several small spots covering the dorsum and sides of the head, trunk and caudal peduncle is a color pattern in many Trichomycterus species ( T. davisi , T. brasiliensis , T. bahianus , T. mimonha , T. mirissumba , T. taroba , and T. rivulatus Valenciennes , among others), in Eremophilus mutisii Humboldt , in Ituglanis amazonicus (Steindachner) , I. eichorniarum (Miranda-Ribeiro) , and I. proops (Miranda-Ribeiro) . Only a detailed phylogenetic analysis will allow inferences about the evolution of the color pattern in the relationships of the Trichomycterus species and of the non monophyletic group “Trichomycterinae”.

Bockmann & Sazima (2005) proposed a group of species, T. maracaya , T. mimonha , T. potschi , and T. vermiculatus , as members of T. brasiliensis species-complex based on the presence of fours longitudinal rows of well-defined blotches, plus I/5-6 pectoral-fin rays. As observed in the type material, T. iheringi does not present the color pattern of four rows of well-defined blotches; hence it could not be included as a member of this group. In addition, all specimens of the type material of T. iheringi have I/7 pectoral-fin rays as observed by Eigenmann (1917 and 1918; P.8), in contrast to that described by Bockmann & Sazima (2005). In a slightly different way Wosiacki (2002) proposed, in a phylogenetic analysis of Trichomycterinae, a different group composed of species with 6 or fewer pectoral-fin rays [ T. candidus , T. naipi , T. mboycy , T. taroba , and Trichomycterus sp. n. (“pelvic-less”) ]. Six or fewer pectoral-fin rays also are present in all Ituglanis species and in the clade composed of Glanapteryginae, Sarcoglanidinae, Tridentinae, Stegophilinae, and Vandelliinae (sensu de Pinna, 1998), interpreted as the result of independent evolution (Wosiacki, 2002).

Bizerril (1994) related T. iheringi , apparently without an analysis of material, to an assemblage of species ( T. mimonha , T. mirissumba , T. triguttatus , T. vermiculatus , and T. concolor ) based on the supraorbital pores being closer to the margin of the eyeball than to the sagittal line, as proposed by Costa (1992). However, as observed in the holotype (Fig. 2) and paratypes, the supraorbital pores of T. iheringi are closer to the sagittal line than the margin of the eyeball, contrary to the proposal of Bizerril (1994).

Phylogenetic assignments: Trichomycterus guaraquessaba and T. iheringi share with all south and southeastern Brazil congeneric species the presence of s6 pores paired, one in each supraorbital canal, except T. alternatus , T. giganteus , T. nigricans , and T. paquequerensis with one epiphyseal pore s6 fused at the sagittal line. Costa (1992) proposed two monophyletic groups for species of Trichomycterus from south and southeastern Brazil: 1) Supraorbital pore s6 paired, each pore closer to the orbit than to the sagittal line; and 2) supraorbital pore s6paired, each pore closer to the sagittal line than to the orbit or fused into a single epiphyseal pore. The position of the supraorbital pore s6 is very variable intra- and interspecifically among Trichomycterinae; however, in a large assemblage of species, the pore s6 opening is directly from the supraorbital canal as in Copionodontinae and Trichogenes , the basalmost groups of Trichomycteridae. Wosiacki (2002) reported that there exists a branching from the supraorbital canal above the epiphyseal bar, in a medial direction, of which the external opening s6 either can be single and median (both sides fused) and at the end of a relatively long canal (equaling the distance between the supraorbital canal and the sagittal plane), or paired having a pore at each side of the sagittal plane between it and the supraorbital canal. The single pore condition is considered as a more derived state. The presence and length of a branch from the supraorbital canal opening either in a single or paired pore as observed in Trichomycterus alternatus , T. brasiliensis , T. giganteus , T. mirissumba , T. mimonha , T. nigricans , and T. paquequerensis probably is a better way of indicating the position of pore s6 than the present reference to distance of the eyes. Regardless, T. guaraquessaba and T. iheringi have the plesiomorphic state without a branching for pore s6. Trichomycterus guaraquessaba and T. iheringi share, with an assemblage of species from south and southeastern Brazil ( T. nigricans , T. davisi , T. stawiarski , T. castroi , T. triguttatus , T. immaculatus , T. itatiayae , T. mirissumba , T. zonatus , T. naipi , T. taboba , T. papilliferus , T. mboycy and T. plumbeus ), the presence of a window at least half of the diameter of the optic foramen in the lateral of the orbito-sphenoid observed by Wosiacki (2002). This feature is an apormophy not observed in the Andeans and trans-Andean species of Trichomycterus .