Lefua costata (Kessler, 1876)

Conway, Kevin W., 2011, Osteology of the South Asian Genus Psilorhynchus McClelland, 1839 (Teleostei: Ostariophysi: Psilorhynchidae), with investigation of its phylogenetic relationships within the order Cypriniformes, Zoological Journal of the Linnean Society 163 (5), pp. 50-154 : 104-108

B. Lefua costata

60. Pharyngobranchial tooth plates ( Fink & Fink, 1981: character 48): (0) present; (1) absent (CI = 1.00; RI = 1.00).

All cypriniform fishes lack pharyngobranchial tooth plates ( Fink & Fink, 1981). At least one pharyngobranchial toothplate is present in all outgroup taxa examined.

61. Anterior basibranchial copula toothplate ( Fink & Fink, 1981: character 50): (0) present; (1) absent (CI = 0.50; RI = 0.50).

All cypriniform fishes lack an anterior basibranchial copula toothplate (basibranchial 1–3 toothplate of Fink & Fink, 1981). A toothplate is associated with the anterior basibranchial copula in all outgroup taxa examined, excluding Denticeps clupeoides ( Greenwood, 1968) . An anterior basibranchial copula toothplate, however, is present in other clupeiforms fishes ( Grande, 1985), and as such the absence of this toothplate in D. clupeoides is probably the result of an event independent of that leading to the loss of this toothplate in cypriniform fishes.

62. Posterior basibranchical copula: (0) with dermal toothplates associated with dorsal surface; (1) with dermal (toothless) plates associated with dorsal surface; (2) without dermal plates or toothplates (CI = 1.00; RI = 1.00).

All cypriniform fishes, except for members of the family Gyrinocheilidae , lack dermal plates on the posterior basibranchial copula. Dermal plates are also absent from the posterior basibranchial copula in the gonorynchiform, characiform, and clupeiform outgroup taxa selected for the analysis, and appear to be absent in other members of these groups based on a survey of the literature. In basal teleosts, such as Elops cf. senegalensis and Hiodon alosoides , two separate toothplates are associated with the posterior basibranchial copula ( Forey, 1973; Hilton, 2002). In members of the family Gyrinocheilidae two toothless dermal plates are associated with the dorsal surface of the posterior basibranchial copula ( Siebert, 1987; Fig. 30E ).

63. Gill-raker teeth ( Johnson & Patterson, 1997): (0) present; (1) absent (CI = 0.50; RI = 0.50).

All cypriniform fishes lack gill-raker teeth ( Johnson & Patterson, 1997; Fig. 31B–D ). Tiny teeth are associated with the gill rakers of all outgroup taxa examined ( Fig. 31A ), excluding Denticeps clupeoides .

64. Gill rakers: (0) small-based elements, base narrower than total height; (1) wide-based elements, base wider than total height (CI = 1.00; RI = 1.00).

In the gastromyzontine balitorids Gastromyzon cranbrooki and Annamia normani , the gill rakers are short, dorsally compressed bones with a wide base, that form a series of low ridges along the branchial arches ( Fig. 31E ). Although the gill rakers of other cypriniform fishes and out-group taxa exhibit a variety of shapes, the width of the base is much shorter than the length of the total length of the gill raker, and as such the gill rakers have a more upright appearance ( Fig. 31A–D ).

65. Gill rakers: (0) without comb-like projections along dorsal edge; (1) with comb-like projections along dorsal edge (CI = 1.00; RI = 1.00).

In members of the Catostomidae the gill rakers exhibit a number of short projections dorsally, giving each gill raker the appearance of a small comb (Willink, 2002; Fig. 31C, D ). In other cypriniform fishes and in out-group taxa the gill rakers lack such projections ( Fig. 31A, B ). Strikingly similar gill rakers to those present in members of the Catostomidae were observed in the cyprinid Xenocypris davidi Bleeker, 1871 (AMNH 10933). The striking similarity between the gill rakers of Xenocypris and members of the Catostomidae is interpreted as the result of homoplasy based on the apical phylogenetic position of the xenocyprines within the cyprinid phylogeny ( Cavender & Coburn, 1992; Saitoh et al., 2006), and the absence of short projections on the gill rakers of other cyprinid fishes closely related to Xenocypris (K.W. Conway, pers. observ.).

66. Gill-filament ossifications ( Conway & Mayden, 2010): (0) absent; (1) present (CI = 1.00; RI = 1.00).

In members of the families Cobitidae , Balitoridae, and Nemacheilidae , a small ossification is present at the base of the cartilaginous rod of the gill filament ( Conway & Mayden, 2010). In other cypriniform fishes and in outgroup taxa gill-filament ossifications are absent, or are present only as small, irregularly arranged ossifications along the length of the cartilaginous rod.

67. Basihyal ( Siebert, 1987: character 21): (0) anterior edge straight or slightly rounded, with a singular cartilaginous tip; (1) anterior edge bifurcated, with two prominent cartilaginous tips (CI = 0.33; RI = 0.33).

In certain members of the families Balitoridae and Nemacheilidae , the anterior tip of the basihyal is bifurcated, with two prominent cartilaginous tips, giving this bone a Y-shaped appearance ( Siebert, 1987; Fig. 30N ). In other cypriniform fishes and in outgroup taxa the anterior tip of the basihyal exhibits a singular cartilaginous tip, and the bone is rod- or spatula-shaped ( Fig. 30A–M ). Siebert (1987) considered the Y-shaped appearance of the basihyal to be a synapomorphy of his Balitoridae (including Nemacheilidae ). Observations on a number of balitorid and nemacheilid taxa during the course of the present study indicate that the shape of the basihyal is much more variable than previously reported by Siebert (1987), ranging from Y-shaped to spatula-shaped. This character is inapplicable to Gastromyzon cranbrooki , which lacks the basihyal entirely ( Fig. 30O ).

68. Sublingual ossifications ( Siebert, 1987: character 16): (0) absent; (1) present (CI = 0.25; RI = 0.84).

In members of the genus Psilorhynchus , Catostomidae , Botiidae , Cobitidae , Balitoridae , Nemacheilidae, and in the gobionine cyprinids, one or two small endoskeletal elements, the sublinguals ( Nelson, 1969), are present ventral to the basihyal, between the tips of the ventral hypohyals. In Psilorhynchus , members of the Catostomidae , and in the gobionines, a single sublingual ossification is present ( Siebert, 1987; Conway & Mayden, 2007; Engeman, Aspinwall & Mabee, 2009; Figs 7, 30D, K, M–O ). In members of the families Botiidae , Cobitidae , Balitoridae (excluding Gastromyzon cranbrooki ), and Nemacheilidae , two small sublinguals are present, one dorsal to the other ( Sawada, 1982; Siebert, 1987; Conway & Mayden, 2007). In G. cranbrooki a single large sublingual element is present between the tips of the ventral hypohyals ( Fig. 30O ). Engeman et al. (2009) provided evidence that the single large sublingual present in Catostomus commersonii (Lacepède, 1803) has two cartilaginous precursors that fuse and ossify during ontogeny. Sublinguals are absent in nongobionine cyprinids, in members of the Gyrinocheilidae , and in all outgroup taxa examined ( Fig. 30A–C, E–H ).

69. Posterior basibranchial copulae ( Siebert, 1987: character 17): (0) complete; (1) segmented (CI = 0.33; RI = 0.90).

In members of the Cobitoidea , excluding members of the Gyrinocheilidae and Barbatula barbatula (Linnaeus, 1758) , the posterior basibranchial copula is segmented ( Siebert, 1987; Fig. 30D, F–J, L–O ). In other cypriniform fishes and in outgroup taxa the posterior basibranchial copula is intact ( Fig. 30A, B, D, K ).

70. Ventral keel on posterior basibranchial copula or derivative elements (modified from Siebert, 1987: character 19): (0) present; (1) absent (CI = 0.33; RI = 0.92).

In members of the genus Psilorhynchus , and in members of the Cyprinidae and Botiidae , the ventral surface of the posterior basibranchial copula is flat. In other cypriniform fishes and in out-group taxa the ventral surface of the posterior basibranchial copula, or its derivative elements, is keeled ( Siebert, 1987). Siebert (1987) considered the presence of a keel on the ventral surface of the posterior basibranchial copula, or its derivative elements, an apomorphic condition. Based on the presence of such a keel on the posterior basibranchial copula of all outgroups examined, and all other non-ostariophysan teleosts examined, this feature is considered to be plesiomorphic.

71. Basibranchial 1 ( Siebert, 1987: character 14): (0) present; (1) absent (CI = 0.20; RI = 0.82).

In members of the Botiidae ( Fig. 30F, G ), Cobitidae ( Fig. 30I, J ), Nemacheilidae ( Fig. 30K, L ), Balitoridae ( Fig. 30M–O ), Vaillantellidae ( Fig. 30H ), and Gyrinocheilidae ( Fig. 30E ), the labeonine cyprinids Osteochilus hasselti and Labeo cf. longipinnis ( Fig. 30B ), and Psilorhynchus pseudecheneis ( Fig. 10F ), basibransilorhynchuschial 1 is absent. In the remaining cypriniform fishes and in out-group taxa basibranchial 1 is present ( Figs 10A–E , 30A, C, D ).

72. Basibranchial 2 ( Siebert, 1987: character 22): (0) anterior edge similar in width or only slightly wider than posterior edge; (1) anterior edge markedly wider than posterior edge (CI = 0.33; RI = 0.90).

In members of the Cobitidae ( Fig. 30I, J ), Balitoridae ( Fig. 30M–O ), and Nemacheilidae ( Fig. 30K, L ), and in certain members of the Botiidae and the labeonine cyprinids ( Fig. 30B ), the anterior edge of basibranchial 2 is much wider than the posterior edge, giving this bone a T-shaped or mushroom-like appearance in dorsal view ( Siebert, 1987). In other cypriniform fishes and in outgroup taxa basibranchial 2 is a roughly rod-shaped element ( Figs 10 , 30A, C–E, H ).

73. Posterior tip of basibranchial 3: (0) on same plane as anterior tip, not intimately associated with the tip of hypobranchial 3: (1) lower than anterior tip, articulating in a concave facet on the anterior tip of hypobranchial 3 (CI = 1.00; CI = 1.00).

In members of the Cobitidae , hypobranchial 3 is closely associated with its antimere along the midline, forming a concave facet in which the posteriormost tip of basibranchial 3 articulates ( Fig. 30I, J ). In some cobitid species a single hypobranchial-3 element is present ( Conway & Mayden, 2007), presumably the result of ontogenetic fusion between the pair of hypobranchial 3 ossifications ( Fig. 30I, J ). The posteriormost tip of basibranchial 3 articulates with this single hypobranchial 3 element in these later species in a similar manner. In other cypriniform fishes and in outgroup taxa an articulation between hypobranchial 3 and basibranchial 3 is absent ( Figs 10 , 30A–H, K–O ).

74. Basibranchial 4 ( Siebert, 1987: character 18): (0) absent; (1) present (CI = 0.33; RI = 0.92).

In members of the genus Psilorhynchus , and in members of the Cobitidae and Balitoridae , basibranchial 4 is present ( Siebert, 1987; Conway & Mayden, 2007; Figs 10 , 30I–K, M ). In other cypriniform fishes and in outgroup taxa the posterior basibranchial copula (or its derivative elements) does not ossify, and remains cartilaginous ( Fig. 30A–H, L, N, O ).

75. Hypobranchial 2: (0) present; (1) absent, only hypobranchial 3 cartilage present (CI = 1.00; RI = 1.00).

In members of the genus Psilorhynchus hypobranchial 2 is absent, and is represented only by its cartilaginous precursor, hypobranchial2 cartilage ( Conway & Mayden, 2007; Fig. 10 ). In other cypriniform fishes and in outgroup taxa hypobranchial 2 is present ( Fig. 30 ).

76. Hypobranchial 3 ( Siebert, 1987: character 15): (0) present; (1) absent, only hypobranchial 3 cartilage present (CI = 0.50; RI = 0.83).

In members of the families Catostomidae and Gyrinocheilidae ( Fig. 30D, E ), and in P. sucatio ( Fig. 10A ), hypobranchial 3 is absent and is represented only by its cartilaginous precursor, hypobranchial3 cartilage ( Siebert, 1987; Conway & Mayden, 2007). In other cypriniform fishes and in outgroup taxa, hypobranchial 3 is present ( Fig. 30A–C, E–O ).

77. Ceratobranchial 5 ( Fink & Fink, 1981: character 52): (0) extending no further dorsally than other ceratobranchials; (1) extending much further dorsally than other ceratobranchials (CI = 0.33; RI = 0.71).

In all cypriniform fishes, excluding members of the Gyrinochelidae and the gastromyzontin balitorids, ceratobranchial 5 extends much further dorsally than ceratobranchials 1–4 ( Fink & Fink, 1981). In members of the Gyrinocheilidae , gastromyzontin balitorids, and outgroup taxa, the dorsalmost tip of ceratobranchial 5 is level with or ventral to the dorsalmost tip of ceratobranchials 1–4.

78. Transversus ventralis V process on ceratobranchial 5 ( Siebert, 1987: character 24): (0) absent; (1) present (CI = 1.00; RI = 1.00).

In members of the families Botiidae , Cobitidae , Balitoridae , Nemacheilidae , and Vaillantellidae the ventrolateral face of ceratobranchial 5 bears a large spine-like process, for the attachment of the transversus ventralis V ( Siebert, 1987). In other cypriniform fishes and in outgroup taxa a transversus ventralis V process is absent.

79. Ceratobranchial 5 teeth ( Fink & Fink, 1981: character 53): (0) teeth bound to Cb5 by collagenous fibers; (1) teeth ankylosed to Cb5 (CI = 1.00; RI = 1.00).

In all cypriniform fishes, excluding members of the Gyrinocheilidae (in which ceratobranchial 5 teeth are absent), the teeth associated with ceratobranchial 5 are ankylosed to the main shaft of that bone ( Fink, 1981; Fink & Fink, 1981). In outgroup taxa the teeth associated with ceratobranchial 5 are bound to the main shaft of the bone by collagenous fibers ( Fink, 1981). This character is inapplicable to Gyrinocheilus .

80. Epibranchial 1: (0) not dorsally overlapped by epibranchial 2; (1) dorsally overlapped by epibranchial 2 (CI = 1.00; RI = 1.00).

In the labeonine cyprinids the posteromedial tip of epibranchial 1 is dorsally overlapped by the anteromedial tip of epibranchial 2 ( Fig. 32A–C ). In other cypriniform fishes and in outgroup taxa epibranchial 1 is not overlapped by epibranchial 2 ( Figs 32D–I , 33).

81. Anterior head of epibranchial 1 ( Siebert, 1987: character 8): (0) not twisted ventrad; (1) twisted ventrad (CI = 0.50; RI = 0.75).

In members of the family Cobitidae , except for Cobitis taenia Linnaeus, 1758 , the anterior head of epibranchial 1 is twisted ventrad ( Siebert, 1987; Fig. 33F). In other cypriniform fishes, including C. taenia , and in outgroup taxa the anterior head of epibranchial 1 is not twisted ventrad ( Figs 11 , 32 , 33A–E, G–I).

82. Anterior edge of epibranchial 1: (0) without large membranous flange on anterior edge; (1) with large membranous flange on anteroventral edge (CI = 1.00; RI = 1.00).

In the labeonine cyprinids the anterior edge of epibranchial 1 exhibits a large, heavily fenestrated flange of membrane bone, which extends far anterior of the main shaft of the bone ( Fig. 32A–C ). This flange probably provides some degree of support to the vomeropalatal organ, present on the dorsal surface of the oral cavity in these fishes ( Reid, 1982; Stiassny & Getahun, 2007). In other cypriniform fishes and in outgroup taxa the anterior edge of epibranchial 1

A. Balantiocheilos melanopterus B. Labeo cf. longipinnis C. Rasbora cephaloteania

Figures

Figure 10. Ventral gill-arch skeleton of Psilorhynchus in dorsal view. Anterior to top of page. A, Psilorhynchus sucatio, CAS 50289, 39.6-mm standard length (SL). B, Psilorhynchus balitora, UMMZ 244782, 31.2-mm SL. C, Psilorhynchus breviminor, ZRC 43452, paratype, 32.0-mm SL. D, Psilorhynchus gracilis, UMMZ 205345, paratype, 39.1-mm SL. E, Psilorhynchus robustus, CMK 17941, paratype, 58.1-mm SL. F, Psilorhynchus pseudecheneis, KU 29517, 41.5-mm SL. Cartilage highlighted in grey. Abbreviations: Bb1–4, basibranchials 1–4; Bh, basihyal; Cb1–5, ceratobranchials 1–5; Gr, gill raker; Hb1–3, hypobranchials 1–3; Hb2–3C, hypobranchials 2–3 cartilage.

Figure 11. Upper gill arch endoskeleton of Psilorhynchus, left side in dorsal view. Anterior to top of page. A, Psilorhynchus sucatio, CAS 50289, 39.6-mm standard length (SL). B, Psilorhynchus balitora, UMMZ 244782, 31.2-mm SL. C, Psilorhynchus breviminor, ZRC 43452, paratype, 32.0-mm SL. D, Psilorhynchus gracilis, UMMZ 205345, paratype, 39.1-mm SL. E, Psilorhynchus robustus, CMK 17941, paratype, 58.1-mm SL. F, Psilorhynchus pseudecheneis, KU 29517, 41.5-mm SL. Cartilage highlighted in grey. Abbreviations: Eb1–4, epibranchials 1–4; Pb2–3, pharyngobranchials 2–3.

Figure 30. Ventral gill arch skeleton of selected cypriniform fishes in dorsal view. Anterior to top of page. A, Balantiocheilos melanopterus, NRM 24037, 36.8-mm standard length (SL). B, Labeo cf. longipinnis, UAIC 14180.55, 51.9-mm SL. C, Rasbora cephalotaenia, BMNH 2000.10.18.34–40, 55.5-mm SL. D, Cycleptus elongatus, UAIC 14922.01, 47.2-mm SL. E, Gyrinocheilus pennocki, UAIC 14180.51, 73.0-mm SL. F, Syncrossus cf. bedmorei, UAIC 14181.01, 61.1-mm SL. G, Yasuhikotakia sidthimunki, UAIC 14166.48, 24.1-mm SL. H, Vaillantella euepiptera, BMNH 2000.10.25.1301–1332, 60.8-mm SL. I, Acantopsis choirorhynchus, AMNH 58307, 128.6-mm SL. J, Lepidocephalichthys cf. guntea, UAIC 14180.56, 57.4-mm SL. K, Barbatula barbatula, AMNH 37608, 77.9-mm SL. L, Lefua costata, UAIC 14183.18, 44.2-mm SL. M, Homaloptera stephensoni, BMNH 2001.1.15.853–872, 37.9-mm SL. N, Sewellia lineolata, UAIC 14169.43, 33.5-mm SL. O, Gastromyzon cranbrooki, UAIC 14288.01, 34.6-mm SL. Cartilage highlighted in grey. Gill rakers not illustrated. Abbreviations: Bb1–5, basibranchials 1–5; Bb4C–6C, basibranchials 4–6 cartilage; Bh, basihyal; Cb1–5, ceratobranchials 1–5; DP, dermal plate; Hb1–3, hypobranchials 1–3; Hb3C/4C, hypobranchial 3/4 cartilage; PC, posterior copula; Sl, sublingual.

Figure 31. Gill rakers of Distichodus antonii and selected cypriniform fishes. A, gill raker from anterior row of ceratobranchial portion of the first gill arch of Distichodus antonii, AMNH 240032, 69.1-mm standard length (SL). B, gill raker from anterior row of ceratobranchial portion of the first gill arch of Abramis brama, AMNH 37594, 95.6-mm SL. C, gill raker from anterior row of ceratobranchial portion of the second gill arch of Myxocyprinus asiaticus, AMNH 77909, 66.6-mm SL. D, gill raker from anterior row of ceratobranchial portion of the second gill arch of Carpiodes cyprinus, UAIC 14314.03, 67.5-mm SL. E, gill-raker row from the fifth gill arch of Annamia normani, BMNH uncat., 63.5-mm SL. Abbreviation: GRT, gill-raker tooth.

Figure 32. Upper gill arch endoskeleton of selected cyprinid fishes, left side in dorsal view. Anterior to top of page. A, Labeo cf. longipinnis UAIC 14180.55, 51.9-mm standard length (SL). B, Osteochilus hasselti, BMNH 2000.6.10.1625, 52.8-mm SL. C, Crossocheilus reticulatus, UAIC 14180.20, 39.6-mm SL. D, Balantiocheilos melanopterus, NRM 24037, 36.8-mm SL. E, Barbus barbus, AMNH 54635, 54.0-mm SL. F, Rasbora cephalotaenia, BMNH 2000.10.18.34–40, 52.4-mm SL. G, Rhodeus sericeus, AMNH 39117, 47.8-mm SL. H, Gobio gobio, AMNH 37609, 83.3-mm SL. I, Phoxinus phoxinus, AMNH 36873, 58.0-mm SL. Cartilage highlighted in grey. Abbreviations: Eb1–4, epibranchials 1–4; Eb5C, epibranchial 5 cartilage; Pb2–3, pharyngobranchials 2–3; Pb4C, pharyngobranchial 4 cartilage.