American seven-spined Gobies
(A general introduction)
by James L. Van Tassell PhD
Tribe Gobiosomini, as originally proposed by Birdsong (1975)
and later revised by Birdsong et al. (1988), unite
what was commonly called the American seven-spined gobies and
several closely allied genera, all endemic to the New World.
Additional genera were added to the tribe by Hoese (1976) and
Birdsong & Robins (1995). Genera currently included
in the tribe are Aboma Jordan and Starks, 1895;
Akko Birdsong and Robins, 1995; Aruma Ginsburg,
1933; Barbulifer Eigenmann & Eigenmann, 1888;
Bollmannia Jordan in Jordan and Bollmann, 1890;
Chriolepis Gilbert, 1892; Elacatinus Jordan,
1904;Eleotrica Ginsburg, 1933a; Enypnias
Jordan & Evermann, 1898; Evermannichthys
Metzelaar, 1920; Ginsburgellus Böhlke & Robins,
1968; Gobiosoma Girard, 1858; Gobulus Ginsburg,
1933; Gymneleotris Bleeker, 1874; Microgobius
Poey, 1876; Nes Ginsburg, 1933;, Ophiogobius
Gill, 1863; Palatogobius Gilbert, 1971; Pariah
Böhlke, 1969; Parrella Ginsburg, 1938;
Psilotris Ginsburg, 1953; Pycnomma Rutter,
1904; Risor Ginsburg, 1933; Robinsichthys
Birdsong, 1988; and Varicus Robins &
Böhlke, 1961. Böhlke and Robins (1968) defined the genus
Gobiosoma to include the subgenera Austrogobius
de Buen, 1950,; Elacatinus Jordan,
1904; Garmannia Jordan and Evermann in Jordan,
1895; Gobiosoma Girard, 1858; and Tigrigobius
Fowler, 1931. While the tribe may not be monophyletic,
later work by Birdsong et al. (1988) inferred a subset
of the group, known as the ‘Gobiosoma Group’ (all
genera except Bollmannia, Microgobius, Palatogobius,
Akko, and Parrella ) to be monophyletic.
of the genera within the tribe are monotypic. They include Aboma,
Akko, Aruma, Eleotrica, Ginsburgellus, Gymneleotris, Nes,
Ophiogobius, Palatogobius, Pariah, Risor, and Robinsichthys.
Several contain only a few species (Pycnomma,
2 spp.; Enypnias, 2 spp.; Psilotris, 3 spp.; Gobulus,
4 spp.; Evermannichthys, 4 spp.; Parrella, 5 spp.)
and are rather distinctive. The most speciose genera,
other than Gobiosoma (37 spp.), are Microgobius (14
spp.) and Bollmannia (13 spp.).
used to unite the Gobiosomini are a dorsal fin pterygiophore
formula of 3-221110 ( in all genera except Evermannichthys,
Pariah, and Risor ), a vertebral count of 11+16-17
(in all but Evermannichthys, and Pariah ), and
the fusion of hypurals 1+2 with 3+4 (in all genera except Aboma,
Akko, Bollmannia, Microgobius, Palatogobius,
and Parrella ) (Birdsong, 1975).
largest genus, Gobiosoma, has been divided into as few
as four or as many as seven subgenera (Ginsburg, 1933b, 1944;
Böhlke and Robins, 1968; Hoese, 1971) based on squamation, cephalic
pore patterns, or sensory papillae patterns. The characters
used to define the genus and to separate the subgenera phenetically
include (1) the number of pores and the extent of development
of the head lateral line canal system, (2) elongation of dorsal
fin spines, (3) precaudal and caudal vertebral numbers, (4)
the shape of the ‘tongue’, (5) the extent of squamation
on the body and (6) the presence or absence of basicaudal scales.
While the species within Gobiosoma are, in general, well-defined,
their phylogenetic relationships have not been investigated
cladistically. Previous authors agree little on the arrangement
of the species within the subgenera or which subgenera to include
within the genus Gobiosoma.
species of Gobiosoma sensu (Böhlke and Robins,
1968) were first studied by Isaac Ginsburg in a series of papers
from 1933 to 1953. He recognized three genera (Aboma,
Gobiosoma, Garmannia ) based on the extent of squamation:
Aboma (monotypic), completely scaled; Garmannia, scaled
at least on the posterior half of the trunk and possessing four
transverse scales on the caudal peduncle; and Gobiosoma,
either completely naked or possessing only two modified basicaudal
scales. Gobiosoma and Garmannia were
divided into numerous subgenera: Gobiosoma into
the subgenera Elacatinus, Nes, Gobiosoma,
Aruma, Dilepidion Ginsburg, 1933, Gerhardinus
Meek & Hildebrand, 1928, and Garmannia into
the subgenera Tigrigobius, Gobicula, Ginsburg
1944, Gobiolepis Ginsburg, 1944, Garmannia,
Gobiohelpis Ginsburg, 1944, Gobiculina Ginsburg,
1944, and Risor, again based on the extent of squamation.
Ginsburg erected the subgenera as temporary holding
areas for the species until he could obtain sufficient data
on each species to change the arrangement. In his final
published papers, he alluded to sensory papillae patterns as
a character that could be used to rearrange the species.
His later work on this subject, however, was never published.
and Robins reviewed the Atlantic species of Gobiosoma and
closely related genera in 1968 and included nominal Pacific
species of Gobiosoma in discussing general relationships.
The genera included in their study were Gobiosoma, Risor,
Ginsburgellus, Nes, Aruma, Enypnias,
Barbulifer, Eleotrica, Gymneleotris, and
Pycnomma. Ten new species and one new genus were
described. They elevated Ginsburg's subgenera Nes
and Aruma to genera and made Garmannia a
subgenus of Gobiosoma. Their classification was
based on the presence or absence of oculoscapular and preopercular
canal pores and numbers of vertebrae rather than on scale patterns
as adopted by Ginsburg. According to Böhlke and Robins,
Gobiosoma was composed of five subgenera (Elacatinus,
Gobiosoma, Austrogobius, Tigrigobius, Garmannia ).
(1971) revised the eastern Pacific species of Gobiosoma
in his doctoral dissertation. The nine Pacific species,
three of which were new, are separated by color pattern, extent
of squamation, presence or absence of head barbels, cephalic
lateral line pore patterns, fin ray counts, sensory papillae
patterns, vertebral counts, elongation of the sphenotic, and
changes in the length to width ratio of the skull. He
included the genus Aboma as a subgenus of Gobiosoma
and commented on the type species, Aboma etheostoma,
as perhaps the most primitive member of Gobiosoma.
Several new species were described and the subgenus Gobiolepis
(Ginsburg 1944) was resurrected.