Gobioidei: Relationships 

 D. F. HoESE 



APPROXIMATELY 500 genera and 2,000 species of gobioid 

 fishes have been named. Currently, about 270 genera are 

 recognized, and it is estimated that the group contains between 

 1,500 and 2,000 species. About 50 families, subfamilies, and 

 tribes have been named. Gobioid fishes are distributed through- 

 out much of the tropical, subtropical and temperate regions of 

 the world, occurring in a variety of habitats in fresh, brackish, 

 and coastal marine waters to depths of about 220 meters on the 

 continental shelf Of the six extant families recognized here, 

 three (Eleotrididae, Gobiidae, and Microdesmidae) are world- 

 wide, and three (Xenisthmidae, Rhyacichthyidae, and Krae- 

 mariidae) are restricted to the Indo-Pacific. Most species of 

 gobioid fishes are benthic, but some are pelagic, many are bur- 

 rowers, and many live in burrows constructed by other organ- 

 isms. 



Much of the early history of the classification of gobioid fishes 

 has been summarized by Iljin (1930), Koumans (1931), and 

 Miller (1973). Early classifications, based on external features 

 were provided by Gunther (1861), Bleeker (1874), Jordan (1923), 

 and Berg ( 1 940). Sanzo (1911) published the first extensive study 

 of the lateralis-system pores and papillae, characters which have 

 come into wide usage in the last 20 years at the generic and 

 specific levels. Regan (1911c) presented the first classification 

 based largely on osteological characters. He established the fam- 

 ily Psammichthyidae (=Kraemariidae), and provisionally placed 

 it with the gobioids, a placement which was not accepted until 

 relatively recently. The study of Regan was largely confined to 

 the cranial osteology, pectoral girdle, and vertebral numbers. 

 Gosline (1955) examined the osteology of a few representatives 

 of the major groups of gobioid fishes, and gave evidence for the 

 placement of microdesmids and kraemariids among the go- 

 bioids. Takagi (1950, 1953) contributed to the classification 

 based on examination of scales and the glossohyal, and later 

 (1966) published an extensive paper on the distribution of the 

 group. Akihito (1963, 1967) studied the scapula in a number of 

 species, and later (1969) presented one of the most detailed 

 studies of the higher classification of gobioid fishes, dealing with 

 major osteological features of 7 1 genera and 85 species, but did 

 not present a classification. Miller ( 1 973) described the osteology 

 of Rhyacichthys, and presented a largely new classification of 

 the group. Birdsong (1975) presented information on the prim- 

 itive character states for several osteological characters and in- 

 dicated presumed trends for each character. He also criticized 

 the classification of Miller and recommended a return to the 

 traditional classification. 



Dawson ( 1 974b) characterized the Microdesmidae and (1973) 

 summarized distributional information on Indo-Pacific species. 

 Rofen (1958) reviewed the Kraemariidae. Matsubara and Iwai 

 (1959) described the osteology of Kraemaria scxradiata. Obrhe- 

 lova (1961) described a new family of gobioid fishes (Pirsken- 

 iidae) from Oligo-miocene fossil material from Europe. 



Few studies have been carried out on the relationships of the 

 suborder to other fishes. Most early workers considered the 

 group related to perciform or scorpaeniform fishes. McAllister 



(1968) and Freihofer (1970) suggested a relationship with the 

 Paracanthopterygii. Other workers have accepted a perciform 

 derivation (Miller, 1973: Springer, 1983; Gosline, 1955), al- 

 though Gosline (1971) suggested that the group might eventually 

 be regarded as a distinct order based on the structure of the 

 suspensorium and the caudal skeleton. No sister group has been 

 postulated. 



Gobioid fishes are characterized by the following features: no 

 parietals; a pelvic intercleithral cartilage: interhyal displaced 

 away from the dorsal end of the symplectic: a gap between 

 symplectic and preoperculum: no orbitosphenoid or basisphe- 

 noid: lacrimal typically present, extending over maxilla, but not 

 forming lower margin of orbit: only one other suborbital rarely 

 present; fourth basibranchial cartilaginous; penultimate verte- 

 bra with a short expanded neural spine and an elongate ex- 

 panded hemal fused to centra; caudal skeleton with one to three 

 epurals, a small free parhypural, an enlarged lower hypural plate 

 articulating with and sometimes fused with urostyle. an enlarged 

 upper hypural plate fused to urostyle, and a small free upper 

 hypural; procurrent caudal rays articulate with cartilaginous 

 plates; lateral line usually absent on body, canals often devel- 

 oped on head, suborbital canal and mandibular canal usually 

 absent; first spine or ray, when spine absent, associated with 

 proximal elements of two pterygiophores (median element of 

 first pterygiophore of second dorsal fin rarely present); last two 

 rays of second dorsal and anal fins closely spaced and articulating 

 with a single pterygiophore in each fin. Meristics are given in 

 Table 152. 



The following groups are recognized: 



Rhyacichthyidae. — The monotypic family Rhyacichthyidae is 

 the most primitive gobioid fish in the following features: bran- 

 chiostegals 6; mesopterygoid and dorsal postcleithrum present; 

 lateral line present on body; an anterior sclerotic; lacrimal and 

 one additional suborbital present; 3 epurals; interhyal adjacent 

 to dorsal end of symplectic; 3 posttemporals; infraorbital and 

 mandibular head canals present; scales with multiple rows of 

 ctenii. Its specializations are related to adaptations to fast flow- 

 ing rocky streams and include: thickened muscular pelvic fins, 

 small mouth, placed ventrally and anteriorly. 



Eleotrididae— The eleotridids, largely confined to freshwater 

 and estuarine environments, are currently definable on the basis 

 of the following primitive features: branchiostegal rays 6; pelvic 

 fins widely separate, pelvic girdle with a short post-pelvic pro- 

 cess, extending well beyond last pelvic ray, pelvic rays in line 

 with pelvic spine; mesopterygoid and dorsal postcleithrum gen- 

 erally present; interorbital normally broad; caudal peduncle long, 

 generally longer than second dorsal base; palatine normally more 

 or less L-shaped, with a short ethmoid process, articulating 

 medially with lateral ethmoid; scapula normally completely os- 

 sified; anterior sclerotic, suborbital (other than lacrimal), post- 

 temporals, and median element of first pterygiophore of second 

 dorsal fin usually absent; first basibranchial cartilaginous, ba- 



588 



