Comparative Cytogenetics 5(4): 259-275, doi: 10.3897/CompCytogen.v5i4.1834
Chromosomal complements of some Atlantic Blennioidei and Gobioidei species (Perciformes)
Tatiana Barbosa Galvão 1, Luiz Antonio Carlos Bertollo 2, Wagner Franco Molina 1
1 Department of Cell Biology and Genetics, Centro de Biociências, Universidade Federal do io Grande do Norte, Campus Universitário, 59078 – 970, Natal, RN, Brazil
2 Department of Genetics and Evolution, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, 13565 – 905, São Carlos, São Paulo, Brazil

Corresponding author: Wagner Franco Molina (

Academic editor: V. Gokhman

received 20 July 2011 | accepted 13 September 2011 | Published 9 November 2011

(C) 2011 Tatiana Barbosa Galvão. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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A remarkable degree of chromosomal conservatism (2n=48, FN=48) has been identified in several families of Perciformes. However, some families exhibit greater karyotypic diversity, although there is still scant information on the Atlantic species. In addition to a review of karyotypic data available for representatives of the suborders Blennioidei and Gobioidei, we have performed chromosomal analyses on Atlantic species of the families Blenniidae, Ophioblennius trinitatis Miranda-Ribeiro, 1919 (2n=46; FN=64) and Scartella cristata (Linnaeus, 1758)(2n=48; FN=50), Labrisomidae, Labrisomus nuchipinnis (Quoy & Gaimard, 1824)(2n=48; FN=50) and Gobiidae, Bathygobius soporator (Valenciennes, 1837)(2n=48; FN=56). Besides variations in chromosome number and karyotype formulas, Ag-NOR sites, albeit unique, were located in different positions and/or chromosome pairs for the species analyzed. On the other hand, the heterochromatic pattern was more conservative, distributed predominantly in the centromeric/pericentromeric regions of the four species. Data already available for Gobiidae, Blenniidae and Labrisomidae show greater intra- and interspecific karyotypic diversification when compared to other groups of Perciformes, where higher uniformity is found for various chromosome characteristics. Evolutionary dynamism displayed by these two families is likely associated with population fractionation resulting from unique biological characteristics, such as lower mobility and/or specific environmental requirements.


Chromosomal evolution, marine fish, Bleniidae, Gobiidae, Labrisomidae


Although karyotypic characteristics for some families of marine fish are already known, information on groups of Perciformes is still significantly disproportionate. Among these, suborders Blennioidei and Gobioidei stand out because of the large number of species they represent.

Suborders Gobioidei, with 2, 121 species, and Blennioidei with 732 species, are spread throughout the tropical zone, typically represented by small specimens with low mobility and the ability to withstand changes in temperature and salinity (Nelson 2006).

Species of Blennioidei and Gobioidei investigated (e.g. Cataudela et al.1973; Garcia et al.1987; Ene 2003) have shown sufficient chromosomal peculiarities for species discrimination and understanding of their evolutionary aspects. In some families, such as Blenniidae, Labrisomidae and Gobiidae, sharing cryptic morphological characteristics combined with poor knowledge of the biological characteristics for many species, contributes to the relative taxonomic inaccuracy of this group. As such, cytotaxonomic markers (Garcia et al. 1987; Caputo 1998; Caputo et al. 2001) and phylogenetic analyses based on molecular data (Wang et al. 2001; Thacker 2003; Gysels et al. 2004; Almada et al. 2005) have been increasingly used when assessing their kinship relations. Indeed, it has been suggested that phylogenetic analyses combine molecular and morphological data (Thacker 2003), as well as cytogenetic information. However, in light of the diversity in these groups, solid chromosome data are not yet sufficiently available, with only 7.5% of Bleniidae species and 4.5% of Gobioidei was karyotyped (Table 1). Despite the scarcity of data, a high degree of chromosomal polymorphism has been characterized among Gobiidae, primarily Robertsonian rearrangements (Caputo et al. 1999, Ene 2003), along with others such as tandemfusions and pericentric inversions (Giles et al. 1985; Thode et al. 1985; Amores et al. 1990).

Table 1.

Cytogenetic data for Blennioidei and Gobioidei (Perciformes).

Suborder/Family Species 2n Karyotype formula FN References
Blenniidae Aidablennius sphynx 48 4m+4sm+40a 56 Cano et al. (1982)
Aidablennius sphynx 48 2st+46a 50 Cataudella and Civitelli (1975)
Atrosalarias fuscus 48 48a 48 Arai and Shiotsuki (1973)
Blennius ocellaris 48 2m+2st+44a 52 Vitturi et al. (1986)
Blennius ponticus 48 16sm+10st+22a 74 Garcia et al. (1987)
Blennius yatabei 48 6sm+12st+30a 66 Arai and Shiotsuki (1974)
Coryphoblennius galerita 48 2m+12sm+34a 62 Garcia et al. (1973)
Dasson trossulus 40 8m+32st/a 48 Arai and Shiotsuki (1974)
Istiblennius enoshimae 48 2m+46a 50 Arai and Shiotsuki (1973)
Istiblennius lineatus 48 48st/a 48 Arai and Shiotsuki (1974)
Lipophrys canevai 48 8st+40a 56 Cataudella and Civitelli (1975)
Lipophrys pholis 46 8m+8sm+30a 62 Garcia et al. (1987)
Lipophrys trigloides 46 4m+4sm+10st+28a 64 Cano et al. (1982)
Lipophrys trigloides 48 2m+6sm+18st+22a 74 Cataudella and Civitelli (1975)
Lipophrys trigloides 48 2m+22sm+2st+22a 74 Garcia et al. (1987)
Lipophrys trigloides 48 2m+6sm+18st+22a 74 Vitturi et al. (1986)
Omobranchus elegans 42 10m+2sm+6st+24a 60 Arai and Shiotsuki (1974)
Omobranchus punctatus 44 4m+40a 48 Arai (1984)
Ophioblennius trinitatis 46 6m+12st+28a 64 Present study
Parablennius incognitus (= Blennius incognitus) 48 4st+44a 52 Cano et al. (1982)
Parablennius pilicornis (= Blennius pilicornis) 48 8st+40a 56 Catalano et al. (1985)
Parablennius gattorugine 48 2m+4sm+42a 54 Vitturi et al. (1986)
Parablennius pilicornis 48 48a 48 Brum et al. (1992)
Parablennius sanguinolentus 48 12st+36a 60 Cataudella et al. (1973)
Parablennius sanguinolentus 48 20sm+10st+18a 78 Garcia et al. (1987)
Parablennius tentacularis 48 48st/a 48 Vasil’ev (1985)
Parablennius tentacularis 48 1st+47a 49 Carbone et al. (1987)
Parablennius tentacularis 47 1sm+46a 48 Carbone et al. (1987)
Salaria fluviatilis 48 48st/a 48 Cataudella and Civitelli (1975)
Salaria pavo 48 8st+40a 56 Cataudella et al. (1973)
Salaria pavo 48 16sm+14st+18a 78 Garcia et al. (1987)
Salaria pavo 48 2st+46a 50 Vasil’ev (1980)
Salarias faciatus 48 48a 48 Arai and Shiotsuki (1973)
Salarias luctuosus 48 48st/a 48 Arai and Shiotsuki (1974)
Scartella cristata (= Blennius cristatus) 48 2st+46a 50 Vitturi et al. (1986)
Scartella cristata 48 2sm+46st/a 50 Brum et al. (1995)
Scartella cristata 48 4st+44a 52 Present study
Clinidae Clinithracus argentatus 48 2st+46a 50 Vitturi et al. (1986)
Labrisomidae Labrisomus nuchipinnis 48 2sm+46a 50 Affonso (2000)
Labrisomus nuchipinnis 48 2st+46a 50 Present study
Eleotridae Dormitator latifrons 46 44m/sm+2st/a 90 Uribe-Alcocer et al. (1983)
Dormitator maculatus 46 34m/sm+12st/a 80 Maldonado-Monroy et al. (1985)
Dormitator maculatus 46 40m/sm+6st/a 86 Molina (2005)
Dormitator maculatus 46 14m+28sm+2st+2a(♀) 13m+28sm+3st+2a(♂) 90 Oliveira and Almeida-Toledo (2006)
Eleotrioides strigatus 44 2m+42st/a 46 Arai and Sawada (1974)
Eleotris acanthopomus 46 46st/a 46 Arai and Sawada (1974)
Eleotris picta 52 52a 52 Uribe-Alcocer and Diaz-James (1996)
Eleotris pisonis 46 2m/sm+42st/a 46 Uribe-Alcocer and Diaz-James (1996)
Eleotris pisonis 46 46a 46 Rocon-Stange (1992)
Eleotris pisonis 46 46a 46 Molina (2005)
Eleotris muralis 46 46a 46 Khuda-Bukhsh and Nayak (1990)
Mogurnda mogurnda 46 6sm+40st/a 52 Arai et al. (1974)
Mogurnda obscura 62 - - Nogusa (1960)
Ophiocara porocephala 48 48a 48 Arai and Fujiki (1979)
Oxyeleotris marmorata 46 2m+2sm+42a 50 Arai and Fujiki (1979)
Gobiidae Aboma latipes 40 40a 40 Arai and Sawada (1974)
Acanthogobius flavimanus 44 44st/a 44 Arai and Sawada (1974)
Acanthogobius flavimanus 44 36st+8a 80 Arai and Kobayashi (1973)
Acanthogobius flavimanus 44 10m/sm/st+34a 54 Arai and Sawada (1975)
Acentrogobius pflaumi 50 48m/sm+2st/a 98 Nogusa (1960)
Amblygobius albimaculatus 44 2m+42st/a 46 Nishikawa et al. (1974)
Aphia minuta 44 44a 44 Caputo et al. (1999)
Aphia minuta 43 42a+1st 42 Caputo et al. (1999)
Aphia minuta 42 1m+1st+40a 44 Caputo et al. (1999)
Aphia minuta 42 1M+1m+40a 44 Caputo et al. (1999)
Aphia minuta 41 2M+1st+38a 44 Caputo et al. (1999)
Apocryptes bato 46 24m+10sm+12a 80 Nayak and Khuda-Bukhsh (1987)
Apocryptes lanceolatus 38 14m+22sm+2st 76 Nayak and Khuda-Bukhsh (1987)
Awaous grammepomus 46 46st/a 46 Khuda-Bukhsh and Barat (1987)
Awaous tajasica 46 46a 46 Stange and Passamani (1986)
Bathygobius fuscus 48 48a 48 Arai and Sawada (1975)
Bathygobius soporator 48 2m+46a 50 Brum et al. (1996)
Bathygobius soporator 48 2m/sm+46a 50 Cipriano et al. (2002)
Bathygobius soporator 48 2m+6st+40a 56 Present study
Bathygobius stellatus 46 2st+44a 48 Vasil’ev (1985)
Bathygobius stellatus 47 1sm+2st+43a 49 Vasil’ev (1985)
Boleophthalmus boddaerty 46 46m/sm 92 Subrahmanyan (1969)
Boleophthalmus glaucus 46 12m+20sm+2st+12a 80 Manna and Prasad (1974)
Boleophthalmus pectinirostrus 46 46st/a 46 Arai and Sawada (1975)
Bostrichthys sinensis 48 4m/sm+44a 52 Arai et al. (1974)
Chaenogobius annularis 44 18sm+26st/a 62 Arai and Sawada (1975)
Chaenogobius annularis 44 36m/sm+8a 80 Arai et al. (1974)
Chaenogobius annularis 44 44a 44 Nogusa (1960)
Chaenogobius castaneus 44 36m/sm/st+8a 80 Nishikawa et al. (1974)
Chaenogobius isaza 44 12sm+32st/a 56 Arai and Sawada (1975)
Chaenogobius urotaenia 44 - - Nogusa (1960)
Chaenogobius urotaenia 42 14sm+28a 56 Yamada (1967)
Chasmichthys dolichognatus 44 44st/a 44 Arai and Sawada (1975)
Chaenogobius gulosus 44 44st/a 44 Arai and Sawada (1975)
Chaenogobius gulosus 44 16m/sm/st+28a 60 Nishikawa et al. (1974)
Ctenogobius criniger 50 34m/sm+6st+10a 90 Arai and Sawada (1974)
Gillichthys mirabilis 44 12sm+32a 56 Chen and Ebeling (1971)
Gillichthys seta 44 6m+14sm+24a 64 Chen and Ebeling (1971)
Glossogobius fasciatopunctatus 44 10m+28sm+2st+4a 84 Fei and Tao (1987)
Glossogobius giuris 46 46a 46 Rishi and Singh (1982)
Gobiodon citrinus 44 2m+42st/a 46 Arai and Sawada (1974)
Gobiodon citrinus 43 1m+42st/a 44 Arai and Sawada (1974)
Gobiodon quinquestrigatus 44 44a 44 Arai and Fujiki (1979)
Gobiodon rivulatus 44 44a 44 Arai and Fujiki (1979)
Gobioides rubicundus 46 2m+26sm+10st+8a 84 Manna and Prasad (1974)
Gobionellus shufeldti 48 48a (♀) 48 Pezold (1984)
Gobionellus shufeldti 47 46a+1m (♂) 48 Pezold (1984)
Gobiosoma macrodon 38 38a 38 Musammil (1974)
Gobiosoma zebrella 38 38a 38 Musammil (1974)
Gobius abei 46 - - Nogusa (1960)
Gobius bucchichi 44 2sm+42a 46 Thode and Alvarez (1983)
Gobius cobitis 46 46a 46 Caputo et al. (1997)
Gobius cruentatus 46 2st+44a 48 Thode and Alvarez (1983)
Gobius fallax 38 8m/sm+30a 46 Thode et al. (1988)
Gobius fallax 39 7m/sm+32a 46 Thode et al. (1988)
Gobius fallax 40 6m/sm+34a 46 Thode et al. (1988)
Gobius fallax 40 7m/sm+33a 47 Thode et al. (1988)
Gobius fallax 41 5m/sm+36a 46 Thode et al. (1988)
Gobius fallax 42 4m/sm+38a 46 Thode et al. (1988)
Gobius fallax 43 3m/sm+40a 46 Thode et al. (1988)
Gobius niger 52 2m+4sm+16st+30a 74 Vitturi and Catalano (1989)
Gobius niger 51 3m+4sm+16st+28a 74 Caputo et al. (1997)
Gobius niger 50 4m+4sm+16st+26a 74 Caputo et al. (1997)
Gobius niger 49 5m+4sm+16st+24a 74 Caputo et al. (1997)
Gobius paganellus 48 2sm+46a 50 Caputo et al. (1997)
Gobius similis 44 ? Nogusa (1960)
Gobiusculus flavescens 46 6m/sm+40a 52 Klinkhardt (1992)
Luciogobius grandis 44 ? Arai (1981)
Luciogobius guttatus 44 ? Arai and Kobayashi (1973)
Mesogobius batrachocephalus 30 16m+14a 46 Ivanov (1975)
Neogobius cephalarges 46 46a 46 Vasil’ev (1985)
Neogobius constructor 42 4m/sm+38a 46 Vasil’ev and Vasil'yeva (1994)
Neogobius cyrius 36 structural polymorphism Vasil’ev and Vasil'yeva (1994)
Neogobius fluviatilis 46 46a 46 Vasil’ev (1985)
Neogobius eurycephalus 32 12m+2sm+18a 46 Ene (2003)
Neogobius eurycephalus 31 13m+2sm+16a 46 Ene (2003)
Neogobius eurycephalus 30 14m+2sm+14a 46 Ene (2003)
Neogobius gymnotrachelus 46 46a 46 Vasil’ev and Grigoryan (1992)
Neogobius kessleri 46 46a 46 Vasil’ev (1985)
Neogobius melanostomus 46 46a 46 Vasil’ev (1985)
Neogobius rhodionovi 46 46a 46 Vasil’ev and Vasil'yeva (1994)
Odontamblyops rubicundus 46 4m+16sm+26st/a 66 Arai and Sawada (1975)
Padogobius martensi 46 1m+3sm+2st+40a 52 Cataudella et al. (1973)
Parioglossus raoi 46 46st/a 46 Webb (1986)
Periophthalmus cantonensis 46 18m+12sm+16st/a 76 Arai and Sawada (1975)
Pomatoschistus lozanoi 37 3m+12sm+10st+12a 62 Webb (1980)
Pomatoschistus microps 46 4m+16sm+20st+6a 86 Klinkhardt (1989)
Pomatoschistus minutus 46 4m+16sm+16st+10a 82 Klinkhardt (1989)
Pomatoschistus minutus 46 18sm+18st+10a 82 Klinkhardt (1992)
Pomatoschistus norvegicus 32 10m+10sm+8st+4a 60 Webb (1980)
Pomatoschistus pictus 46 22m/sm+12st+12a 80 Klinkhardt (1992)
Proterorhinus marmoratus 46 46a 46 Rab (1985)
Pterogobius elapoides 44 14sm+30st 88 Arai and Kobayashi (1973)
Pterogobius zonoleucus 44 14sm+30st 88 Arai and Sawada (1975)
Quietula guaymasiae 42 6m+4sm+32a 52 Cook (1978)
Quietula y-cauda 42 42a 42 Cook (1978)
Rhinogobius brunneus 44 44a 44 Nishikawa et al. (1974)
Rhinogobius flumineus 44 44a 44 Arai and Kobayashi (1973)
Rhinogobius giurinus 44 44a 44 Nishikawa et al. (1974)
Rhodoniichthys laevis 42 16m/sm+26st 84 Arai et al. (1974)
Sicyopterus japonicus 44 10m+10sm+24a 64 Arai and Fujiki (1979)
Synechogobius hasta 44 2m+42st/a 46 Arai and Sawada (1975)
Tridentiger obscurus 44 10m/sm+34a 54 Arai et al. (1974)
Tridentiger trigonocephalus 44 28m/sm/st+16a 72 Arai et al. (1973)
Tridentiger trigonocephalus 46 16sm+6st+24a 68 Fei and Tao (1987)
Trypauchen vagina 46 12m+6sm+10st+18a 74 Khuda-Bukhsh (1978)
Tukugobius flumineus 44 44a 44 Nadamitsu (1974)
Zosterisessor ophiocephalus (= Gobius ophiocephalus) 46 46a 46 Vasil’ev (1985)
Zosterisessor ophiocephalus (= Gobius ophiocephalus) 45 1st+45a 47 Vasil’ev (1985)
Zosterisessor ophiocephalus 46 2m/sm+44a 48 Caputo et al. (1996)

The present study focuses on the karyotypic characterization of some Atlantic species of the families Blenniidae, Ophioblennius trinitatis Miranda-Ribeiro, 1919 and Scartella cristata (Linnaeus, 1758), Labrisomidae, Labrisomus nuchipinnis (Quoy & Gaimard, 1824)and Gobiidae, Bathygobius soporator (Valenciennes, 1837), through conventional chromosomal analysis, characterization of nucleolar organizer regions (Ag-NORs) and the distribution pattern of C-positive heterochromatin (C-banding) in chromosomes, discussing evolutionary aspects.

Material and methods

A total of 25 specimens of Ophioblennius trinitatis (7♂, 4♀ and 14 indeterminate), 11 specimens of Scartella cristata (4♂, 5♀ and 2 indeterminate), 13 specimens of Labrisomus nuchipinnis (4♂, 4♀ and 5 indeterminate) and 12 specimens of Bathygobius soporator, (5♂, 5♀ and 2 indeterminate) were used for chromosome analysis. Ophioblennius trinitatis specimens came from the coast of Rio Grande do Norte (5°13'1.73"S; 35°9'57.85"W), northeastern Brazil (n=1), and the Saint Peter and Saint Paul (n=8) (00°55'02"N; 29°20'42"W) and Fernando de Noronha (n=16) (3°52'11"S; 32°26'13"W) archipelagos. The remaining specimens were collected on the coast of Rio Grande do Norte. Individuals were previously submitted to mitotic stimulation with compound attenuated antigens, for 24 to 48 hours (Molina 2001, Molina et al. 2010), anesthetized with clove oil (Eugenol) and sacrificed for the removal of anterior kidney fragments. Sexing of specimens was performed by macroscopic and microscopic examination of the gonads. Chromosome preparations were obtained from kidney cells (Gold et al. 1990). Nucleolar organizer regions (NORs) were identified by stain with silver nitrate - Ag-NORs (Howell and Black 1980) and C-positive heterochromatin sites through C-banding (Sumner 1972).

Metaphase preparations were examined and photographed on an Olympus BX50 photomicroscope, using an Olympus DP70 digital camera system. Chromosomes were classified according to the position of the centromere in metacentrics (m), submetacentrics (sm), subtelocentrics (st) and acrocentrics (a) (Levan et al. 1964) and organized in order of decreasing size. The chromosome formula and FN (fundamental number or number of chromosomal arms) were established for each species, considering acrocentric chromosomes with a single arm and the remaining chromosomes exhibiting two arms.

Results Cytogenetic analyses of Blenniidae species (Blennioidei)

Ophioblennius trinitatisshowed 2n=46, with a chromosome formula equal to 6m+12st+28a (FN=64), irrespective of sex. Although chromosomes showed a gradual decline in size, the smallest acrocentric pairs corresponded to approximately one-third of the largest metacentric pairs. Nucleolar organizer regions are located in the terminal portions of the short arm on pair 9, the smallest subtelocentric pair. C-positive heterochromatin is discretely located in the centromeric/pericentromeric region of the chromosomes (Fig. 1a, b).

Figure 1.

Karyotypes underGiemsa staining a, c, e, g and C-banding b, d, f, h of Ophioblenius trinitatis; a, b Scartella cristata; c, d Labrisomus nuchipinnis; e, f and Bathygobius soporator; g, h Ag-NOR-bearing chromosome pairs are highlighted.

Scartella cristata showed 2n=48 chromosomes, with a chromosome formula equal to 4st+44a (FN=52). The karyotype also displays a gradual reduction in chromosome size. However, the largest chromosome pair exhibits only double the size in relation to the smallest karyotype pair. Ribosomal sites are located on the terminal portions of the short arms on chromosome pair 1. C-positive heterochromatin is also reduced and located in the centromeric regions of chromosomes (Fig. 1c, d).

Cytogenetic analyses of Labrisomidae and Gobiidae species (Gobioidei)

Labrisomus nuchipinnis (Labrisomidae) showed 2n=48 chromosomes with a chromosome formula of 2st+46a (FN=50), showing relatively more differentiated size between the largest and smallest chromosomes of the karyotype. Nucleolar organizer regions are in the terminal portions of the long arms on pair 2, corresponding to the largest pair of acrocentric chromosomes. C-positive heterochromatin was showed in the centromeric/pericentromeric region of all chromosome pairs, in relatively conspicuous blocks (Fig. 1e, f).

Bathygobius soporator (Gobiidae) also displayed the karyotype composed of 2n=48 chromosomes, but with the chromosome formula distinct from that of Labrisomus nuchipinnis, specifically, 2m+6st+40a (FN=56). Size difference between the largest and smallest chromosomes of the karyotype was far less pronounced. Ribosomal sites were on the terminal portions of the short arms on chromosome pair 4. C-banding showed discrete heterochromatic regions in the centromeric regions of most chromosomes and telomeric regions of some acrocentric pairs (Fig. 1g, h).


Though many perciform families display a conserved karyotype pattern, with 2n=48 acrocentric chromosomes, some groups demonstrate dynamic tendencies in relation to chromosome evolution (Molina 2007). Much of identifiable chromosome diversity is attributed to pericentric inversions, the most common mechanism of chromosome evolution in this order (Galetti et al. 2000, 2006).

Representatives of the suborder Blennioidei (e.g., Carbone et al. 1987) and Gobioidei (e.g., Arai and Sawada 1974, 1975; Thodeet al. 1988; Oliveira and Almeida-Toledo 2006) stand out for their greater karyotype variability and diversity. This includes species with conserved karyotyes and those that are highly diversified.

Within the Blennioidei, the Blenniidae, a monophyletic family, is divided into six tribes including Salariini and Parablenniini which, in turn, include the Atlantic species Ophioblennius trinitatis and Scartella cristata respectively (Nelson 2006). Comparisons of mitochondrial DNA sequences in samples of Ophioblennius Gill, 1860 collected throughout the Atlantic suggest that the genus consists of six distinct lineages. One of these corresponds to species found in the Pacific, while the rest are recorded in the biogeographic provinces of the Atlantic: Brazilian, Caribbean, Mid-Atlantic, Sao Tome and Azores/Cape Verde (Muss et al. 2001). Chromosome characteristics reported here for Ophioblennius trinitatis are the first for the genus, exhibiting 2n=46, 6m+12st+28a and FN=64. The relatively low diploid number and higher fundamental number in relation to the mean of other species of Blenniidae (Table 1), as well as the presence of large metacentric chromosomes, suggests pericentric inversion events and the occurrence of Robertsonian translocation involving two of its chromosome pairs. In turn, Scartella cristata, while also belonging to the family Blenniidae, has a distinct karyotype of 2n=48, 4st+44a and FN=52. Thus, Scartella cristata differs from Ophioblennius trinitatis in that it contains an extra pair of chromosomes, lacks metacentric chromosomes and has different numbers of subtelocentric and acrocentric chromosomes in the karyotype. The karyotype of the Scartella cristata population studied here differs from the karyotypes previously described for the coastal population of Rio de Janeiro (SE Brazil), with 2sm+46st/a (Brum et al. 1994), and the Mediterranean population, with 2st+46a (Vitturi et al. 1986). Nevertheless, despite the growing number of discordant karyotype descriptions between populations on the NE and SE coasts of Brazil, one cannot rule out that these differences may arise from the difficulty in precisely defining types of cryptic chromosomes in the karyotype of this species.

In spite of displaying relative diversity in chromosome structure, only 18.5% of Blennioidei species exhibit differences in the basal diploid number, 2n=48 chromosomes. As shown in table 1, diploid numbers for representatives of this suborder vary between 2n=40, found in Dasson trossulus (Jordan & Snyder, 1902)(Arai and Shiotsuki 1974) and 2n=52 in Gobius niger Linnaeus, 1758 (Vitturi and Catalano 1989), but with a conspicuous modal value of 2n=48.

In contrast to Blennioidei, suborder Gobioidei shows much more dynamic karyotype evolution, demonstrating highly variable karyotype patterns, where the diploid number ranges from 2n=30 for Neogobius eurycephalus (Kessler, 1874) (Ene 2003), to 2n=62 in Mogurnda mogurnda (Richardson, 1844) (Nogusa 1960). Cytogenetic data for 95 species show that only 9.6% have 2n=48 chromosomes, whereas the highest frequencies observed correspond to 2n=46 in 40% of species investigated, and 2n=44 in 32% (Table 1). As such, both Gobioidei species studied here are included in the group showing 2n=48 chromosomes, Labrisomus nuchipinnis with 2st+46a and FN=50 and Bathygobius soporator with 2m+6st+40a and FN=56. Thus, Bathygobius soporator differs from Labrisomus nuchipinnis in the presence of metacentric chromosomes and different numbers of subtelocentric and acrocentric chromosomes in the karyotype.

Among chromosome rearrangements involved in karyotypic differentiation of Gobiidae, Robertsonian fusions stand out, and are likely the most common event in this group (Amores et al. 1990; Galetti et al. 2000). However, other more complex changes in karyotypic structure (Thode et al. 1988; Vitturi and Catalano 1989; Caputo et al. 1997; Caputo et al. 1999), as well as the presence of different sex chromosomes (e.g., Pezold 1984; Baroiller et al. 1999), can also be observed, corroborating the high dynamic evolution that characterizes suborder Gobioidei. It has been suggested that the baseline/ancestral karyotype for Gobiidae would consist of 2n=46 acrocentric chromosomes (Vasil’ev and Grigoryan 1993), from which an increase in bi-brachial chromosomes would characterize more derived karyotypes. Based on this proposal, Bathygobius soporator (FN=56) would experience a greater number of structural rearrangements during its karyotypic evolution process in relation to Labrisomus nuchipinnis (FN=50).

Location and frequency of Ag-NOR sites are efficient cytotaxonomic markers in many groups of fish (Caputo 1998). Among species of Gobiidae, at least six different arrangement patterns for nucleolar organizer regions have been identified (Fig. 2), which supports the occurrence of intense karyotypic diversification mechanisms in this group. Thus, Ag-NOR sites can be found (a) in the telomeric region on the short arm of a single pair of acrocentric chromosomes, as in Gobius fallax Sarato, 1889 (Thode et al. 1983) and Gobius paganellus Linnaeus, 1758 (Caputo 1998); (b) in the telomeric region on the long arm of a single pair of acrocentrics, such as in Zosterisessor ophiocephalus (Pallas, 1814) (Caputo 1998); (c) in the interstitial/pericentromeric region on the long arm of a single pair of acrocentric chromosomes, as seen in Proterorhinus marmoratus (Pallas, 1814) (Ráb 1985) and Gobius cobitis Pallas, 1814 (Caputo 1998); (d) in the telomeric region on the short arm of a single subtelocentric pair, described in Bathygobius soporator;(e) in the interstitial/pericentromeric region on the long arm of a single metacentric pair, observed in Neogobius eurycephalus (Ene 2003); and (f) in the telomeric regions on the short arms of two acrocentric chromosome pairs, recorded in Gobiusculus flavescens (Fabricius, 1779) (Klinkhardt 1992).

Figure 2.

Ag-NOR phenotypes a–f described in species of Gobiidae. Ag-NORs sites described in the karyotypes of Gobiidae species were found a in the telomeric region on the short arm of a single pair of acrocentric chromosomes b in the telomeric region on the long arm of a single pair of acrocentrics c in the interstitial/pericentromeric region on the long arm of a single pair of acrocentric chromosomes d in the telomeric region on the short arm of a single subtelocentric pair e in the interstitial/pericentromeric region on the long arm of a single metacentric pair and f in the telomeric regions on the short arms of two acrocentric chromosome pairs.

Few data are available on ribosomal sites for Labrisomidae. Ag-NORs in Labrisomus nuchipinnis exhibit the phenotype (b) described above, in addition to both species of Blenniidae, Ophioblennius trinitatis and Scartella cristata, which may suggest an ancestral condition for this location.

In contrast, other chromosome characteristics, such as C-positive heterochromatin distribution, may be more conserved. This occurs in several species of Percifomes where discrete blocks are preferentially located in the centromeric/pericentromeric regions of chromosomes (Molina 2007). This pattern is repeated in Scartella cristata, Ophioblennius trinitatis and Labrisomus nuchipinnis, as well as in some Gobiidae, such as Gobius cobitis, Zosterisessor ophiocephalus and Neogobius eurycephalus (e.g. Caputo et al. 1997; Ene 2003). In Bathygobius soporator, in addition to centromeric/pericentromeric regions, heterochromatic sites are also observed in terminal regions of some chromosomes. This arrangement has already been described for other Gobiidae, including Gobius paganellus and Gobius niger, where pericentromeric and telomeric heterochromatic regions are distributed among almost all chromosomes (Amores et al. 1990; Caputo et al.1997).

Moreover, karyotypic diversity present in Gobioidei is increased by the occurrence of chromosome polymorphisms frequently observed in this group. This is particularly evident in several examples of intraspecific karyotypic variability, as well as polymorphisms involving different types of chromosome rearrangements, such as in Gobius niger (Vitturi and Catalano 1989; Caputo et al. 1997) and Gobius fallax (Thode et al. 1988). Data obtained for the paedomorphic Gobiidae Aphia minuta (Risso, 1810) also show variations in the diploid number and chromosome formula, resulting in five different cytotypes (2n=41–44 and FN=42-44) (Caputo et al. 1999). Similar karyotypic variability was reported in Neogobius eurycephalus, where three specific cytotypes (2n=30, 31 and 32) were associated to the occurrence of centric fusions (Ene 2003). All these examples demonstrate clear chromosomal dynamism, with possible transitions to new karyotype patterns.

In fact, karyotypic diversity among Blennioidei and Gobioidei seems to accompany phyletic diversification of these groups. This is a result of vicariant factors (Pampoulie et al. 2004) and could be favored by their low dispersive potential (Fanta 1997), as well as ecological specificities that favor population fractionation in this family (Huyse et al. 2004). The present study also highlight the importance of ribosomal sites as effective chromosomal markers in the further cytogenetic studies in gobiids species.


We are grateful to the National Council of Technological and Scientific Development (CNPq) for its financial support (Project 556793/2009-9) and to José Garcia Júnior for taxonomic identification of species.

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