scholarly journals Anatomy and evolution of the pectoral filaments of threadfins (Polynemidae)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Paulo Presti ◽  
G. David Johnson ◽  
Aléssio Datovo

Abstract The most remarkable anatomical specialization of threadfins (Percomorphacea: Polynemidae) is the division of their pectoral fin into an upper, unmodified fin and a lower portion with rays highly modified into specialized filaments. Such filaments are usually elongate, free from interradial membrane, and move independently from the unmodified fin to explore the environment. The evolution of the pectoral filaments involved several morphological modifications herein detailed for the first time. The posterior articular facet of the coracoid greatly expands anteroventrally during development. Similar expansions occur in pectoral radials 3 and 4, with the former usually acquiring indentations with the surrounding bones and losing association with both rays and filaments. Whereas most percomorphs typically have four or five muscles serving the pectoral fin, adult polynemids have up to 11 independent divisions in the intrinsic pectoral musculature. The main adductor and abductor muscles masses of the pectoral system are completely divided into two muscle segments, each independently serving the pectoral-fin rays (dorsally) and the pectoral filaments (ventrally). Based on the innervation pattern and the discovery of terminal buds in the external surface of the filaments, we demonstrate for the first time that the pectoral filaments of threadfins have both tactile and gustatory functions.

Zootaxa ◽  
2012 ◽  
Vol 3586 (1) ◽  
pp. 329 ◽  
Author(s):  
ZACHARY S. RANDALL ◽  
LAWRENCE M. PAGE

The genus Homalopteroides Fowler 1905 is resurrected and distinguished from the genus Homaloptera van Hasselt 1823based on a combination of characters including a unique mouth morphology, dorsal-fin origin over pelvic fin,≤60 lateral-line scales, and≤30 predorsal scales. Species included in Homalopteroides are H. wassinkii (Bleeker 1853), H. modestus(Vinciguerra 1890), H. rupicola (Prashad & Mukerji 1929), H. smithi (Hora 1932), H. stephensoni (Hora 1932), H. weberi(Hora 1932), H. tweediei (Herre 1940), H. indochinensis (Silas 1953), H. nebulosus (Alfred 1969), H. yuwonoi (Kottelat1998), and possibly H. manipurensis (Arunkumar 1999). Homalopteroides modestus (Vinciguerra 1890) is a poorlyknown species that was originally described from the Meekalan and Meetan rivers of southern Myanmar. It occurs in theSalween, Mae Khlong, and Tenasserim basins, and can be distinguished from all other species of Homalopteroides by thecombination of caudal-fin pattern (black proximal and distal bars, median blotch), 15 pectoral-fin rays, pectoral-fin lengthgreater than head length, 5½–6½ scales above and 5–6 scales below the lateral line (to the pelvic fin), 39–44 total lateral-line pores, no axillary pelvic-fin lobe, pelvic fin not reaching anus, orbital length less than interorbital width in adult, and maxillary barbel reaching to or slightly past the anterior orbital rim.


Zootaxa ◽  
2017 ◽  
Vol 4244 (2) ◽  
pp. 207 ◽  
Author(s):  
ÍTHALO DA SILVA CASTRO ◽  
WOLMAR BENJAMIN WOSIACKI

A new species of Ituglanis is described from rio Iratapuru, near the rio Jari, Amapá, Brazil. The new species is distinguished from all congeners by the reduced number of post-Weberian apparatus vertebrae (36 or 37); the low number of paired ribs (2); the low number of interopercular odontodes (12–15); the number of branchiostegal rays (7 or 8); the presence of elongated fontanel in parieto-supraoccipital; the pectoral-fin rays (i,5); head length (18.9–25.0); and the presence of pores supraorbital s1, infraorbitals i1 and i3 of the laterosensory system. The new taxon has a reduced body size and fully ossified skeleton, but does not display a large number of paedomorphic traits compared to congeners. Comments about taxonomy and intrageneric comparisons are made, and paedomorphic in Ituglanis is discussed. Thoughts about conservation of the new species are presented. 


Zootaxa ◽  
2007 ◽  
Vol 1614 (1) ◽  
pp. 53-60 ◽  
Author(s):  
THIAGO N.A. PEREIRA ◽  
PAULO H.F. LUCINDA

A new characid species, Jupiaba elassonaktis, is described from the rio Tocantins drainage. The new species is distinguished from its congeners by the following combination of characters: medial cusps of premaxillary teeth much larger than remaining cusps, dentary teeth decreasing abruptly in size from the fifth tooth backwards, first dorsaland anal-fin rays not prolonged by an elongate filament, presence of a vertically elongate humeral spot, 33–39 scales on lateral line, 5–7 scales series above lateral line, 9–11 pectoral-fin rays, and a incomplete series of median predorsal scales.


2008 ◽  
Vol 6 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Lúcia H. Rapp Py-Daniel ◽  
Ilana Fichberg

Rineloricaria daraha, new species, is described from the rio Daraá, tributary of rio Negro, northwestern Amazonas State, Brazil. The new species is diagnosed by having seven branched pectoral-fin rays, finger-like papillae on the lower lip, a large multi-angular preanal plate, and at least four quadrangular plates of variable size surrounding the preanal plate. The new species is known only from rio Daraá and its waterfalls.


Zootaxa ◽  
2020 ◽  
Vol 4722 (1) ◽  
pp. 68-76
Author(s):  
BUNGDON SHANGNINGAM ◽  
SHIBANANDA RATH ◽  
ASHA KIRAN TUDU ◽  
LAISHRAM KOSYGIN

A new species of the genus Osteobrama is described from the Mahanadi River, Tikarpada, Angul District, Odisha state, India. Osteobrama tikarpadaensis, new species, differs from its congeners in having two pairs of minute barbels; iii–iv unbranched dorsal-fin rays with 25–33 serrae on the last unbranched ray; 15–16 branched pectoral-fin rays, and 25–27 branched anal-fin rays. The status of Osteobrama dayi is discussed and shown to be a valid species. A key to the species of the genus is provided. 


Zootaxa ◽  
2004 ◽  
Vol 744 (1) ◽  
pp. 1 ◽  
Author(s):  
ALINE R. ALENCAR ◽  
WILSON J.E.M. COSTA

Two new species of Trichomycterus from isolated small river basins of southeastern Brazil are described: T. pantherinus, new species, from the Rio Santa Maria da Vit ria basin, and T. caudofasciatus, new species, from the Rio Itabapoana basin. Both new species are diagnosed by a combination of morphological features, also occurring in T. alternatus and T. longibarbatus, including number of pectoral-fin rays, odontodes and branchiostegal rays, long filamentous first pectoral-fin ray and wide opercular patch of odontodes. Trichomycterus pantherinus differs from other congeners by possessing a light orangish yellow flank with dark brown to black rounded spots. Trichomycterus caudofasciatus is distinguished from other species of the genus by having four gray bars on the caudal fin.


Zootaxa ◽  
2008 ◽  
Vol 1686 (1) ◽  
pp. 29 ◽  
Author(s):  
MARCELO KOVAČIĆ ◽  
ULRICH K SCHLIEWEN

Gorogobius stevcici sp. nov. is described from the São Tomé Islands, Gulf of Guinea. Although it exhibits the unique combination of characters of Gorogobius Miller, it differs from present generic diagnosis of that genus. Therefore, a revised generic diagnosis and description of Gorogobius is provided. The new species differs from its only congener, G. nigricintus, by (1) presence of pore β; (2) row g anteriorly ends more or less in front of row o; (3) transverse interorbital row p present; (4) snout with four median preorbital rows; (5) 37–41 vs. 29–33 longitudinal scale rows; (6) 22–24 vs. 18 predorsal scales; (7) 9 vs. 10–11 anal fin rays; (8) 17 vs. 18–20 pectoral fin rays; (9) coloration.


Zootaxa ◽  
2008 ◽  
Vol 1715 (1) ◽  
pp. 43 ◽  
Author(s):  
RONALD E. WATSON

Stiphodon carisa, n. sp., is described based on material collected in the southernmost watershed in Lampung Province, Sumatra, Indonesia. Stiphodon carisa, n. sp., differs from all other congeners by a combination of characteristics that include having 9 second-dorsal fin rays; 15 pectoral-fin rays; 41–59 premaxillary teeth; predorsal scales sexually dimorphic in number, male with 5–11 and female with 8–16; 25–35 lateral scales; slightly embedded cycloid scales present on belly; male with a triangular-shaped first-dorsal fin with third and/or fourth spines longest but not filamentous and a patch of white fatty tissue posterior to pectoral-fin base; female usually with 5 (4–5) dusky to blackish blotches or spots along lateral midline from second-dorsal fin with usually 4 (3–4) posterior-most spots positioned close together on caudal peduncle, dusky band extending from anterior to eye to upper hypural base usually indistinct posterior to pectoral-fin base, with or without a dusky or black gular blotch; in some females xanthism exists which fades in preservation and in life yellow with orange to bright red markings. Stiphodon semoni is a species common in hill streams of eastern Indonesia and Papua New Guinea and is reported here for the first time from streams entering the Indian Ocean in Lampung Province, Sumatra, Indonesia.


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