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ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



to near or fused with caudal; eyes rudimentary and placed for- 

 ward in orbit; lateral process of symplectic large; 2 epurals. The 

 worldwide group occurs in estuaries or off river mouths, and 

 includes about 10 genera and the following named taxa: Go- 

 bioididae, Taenioididae, Trypauchenidae. 



Sicydiinae.— Tongue fused to floor of mouth or free only at tip, 

 highly modified jaw suspension; thickened and highly branched 

 pelvic rays and fleshy pads at tips of pelvic spines. The world- 

 wide group occurs in freshwater and includes about 5 or more 

 genera and the following included taxa: Sicydiaphiinae (in part). 



Gobiinae.— The worldwide group includes about 200 genera 

 and is not easily definable. The group includes the following 

 named higher taxa: Aphyinae, Austrolethopinae, Benthophiliae, 

 Brachygobii, Calleleotrinae, Chaeturichthyi, Croilinae, Crystal- 

 logobiinae, Doliichthyidae, Gobiodontinae. Gobiosomini, 

 Gymnogobiini, Latrunculini, Lebetinae, Leioterinae, Luciogo- 

 biinae, Platygobii, Rhinogobiinae, Triaenophorichthyini, Tri- 

 dentigeriinae, Valencienninae. 



Kraemariidae(=Psammichthyidae.)— The family agrees in most 

 features with the Gobiidae, being specialized in having a large 

 amount of cartilage in the skeleton and 3 pectoral radials. The 

 group is restricted to the Indo-Pacific and includes 2 genera. 



Relationships 



Most workers have generally agreed that the Rhyacichthyidae 

 and Eleotrididae represent the most primitive gobioid fishes 

 characterized by 6 branchiostegal rays, a mesopterygoid, and 

 dorsal postcleithrum. In addition other primitive features, not 

 found in gobiids are sometimes present, such as an anterior 

 sclerotic, lower suborbital (other than lacrimal), and extrascap- 

 ulae. Most other features generally retain a primitive nature in 

 eleotridids, such as 2 epurals, ossified scapula, head canals, when 

 present, separate between eyes, and a ventral postcleithrum. 

 Gobiids, microdesmids, and kraemariids have 5 branchiostegal 

 rays and lack a mesopterygoid and dorsal postcleithrum (with 

 over two thirds of the genera examined). These differences in 

 organizational grades have lead some workers to suggest that 

 the advanced gobiid level of organization may be polyphyletic 

 (Springer, 1983). 



The primary innovate character defining the gobiid fishes is 

 the development of a pelvic cup-shaped disc, formed by mem- 

 branes connecting the inner pelvic rays and two pelvic spines 

 (interspinal membrane or frenum); with the forward and ventral 

 rotation of the pelvic spines on the pelvic girdle. It has been 

 shown that reef gobiids often have secondarily separate pelvic 

 fins (Hoese, 1971), although most species retain a rudiment of 

 the interspinal membrane and the typical gobiid pelvic spine 

 orientation. Consequently, the question of whether gobiid fishes 

 are monophyletic depends in part on whether the disc has evolved 

 independently in various gobiid groups. Studies of other gobiid 

 specializations, although incomplete, have not indicated that 

 gobiids are polyphyletic. For example Regan (191 1 c) first noted 

 that the eleotridids have an L-shaped palatine and gobiids a 

 T-shaped palatine. In eleotridids the ethmoid process of the 

 palatine is short and articulates directly with the middle of the 

 lateral ethmoid, while in gobiids the ethmoid process is typically 

 long, extending across to the median ethmoid, which is displaced 

 ventrally. Similarly in gobiids there is an intemeural gap be- 



tween the two dorsal fins (a space between two neural arches 

 without a pterygiophore). Primitively in eleotridids, the pteryg- 

 iophores of the two dorsal fins are continuous, without a gap. 

 From the relationship between the pterygiophores of the second 

 dorsal and the anal fins, it appears that the gap in gobiids forms 

 from a posterior shift of the second dorsal fin. The intemeural 

 gap also occurs in Rhyacichthys and Xenisthmus, and several 

 eleotridid genera from New Guinea, Australia, and New Zealand 

 (Gobiomorphus, Philypnodon, Grahamtchthys, and two new 

 genera) and the Central American genus Leptophilypnus. Struc- 

 tural comparisons indicate that Rhyacichthys probably obtained 

 the gap by loss of a dorsal spine or forward shift of the posterior 

 dorsal spines. It is currently unknown whether the Xenisthmidae 

 and the Gobiomorphus- Leptophilypnus group are convergent 

 with gobiids or represent sister groups. Both groups sometimes 

 lose primitive eleotridid features such as the mesopterygoid and 

 dorsal postcleithrum. In general body form the Gobiomorphus- 

 Leptophilypnus group most closely approach the gobiid body 

 form expected of an ancestral gobiid. Although currently placed 

 with the eleotridids further studies are underway to determine 

 the relationships of the genera in the group. 



The microdesmids also represent a gobiid level of organiza- 

 tion, in lacking several primitive features, but their relationships 

 to other gobioid fishes are unclear. The group is characterized 

 primarily by the unique specialization of having an elongate 

 posterior pelvic process. The two subfamilies have other spe- 

 cializations in common and show similar trends, with the Pter- 

 eleotrinae representing the primitive sister group. The micro- 

 desmids retain a primitive palatine-ethmoid articulation, and 

 the posterior pelvic process probably represents an elongation 

 of the short posterior pelvic process of eleotridids. Microdes- 

 mids share with gobiids the loss of the anterior branchiostegal 

 ray. The strong compression of the head may have lead inde- 

 pendently to the loss of the anterior branchiostegal ray. Unfor- 

 tunately no immediate sister group is known, although on the 

 basis of the intemeural gap, the Xenisthmidae represent a pos- 

 sible group. Although the inner rays of the two pelvic fins are 

 sometimes connected in microdesmines, no species is known 

 with an interspinal membrane. The microdesmines have pre- 

 sumably secondarily lost the intemeural gap. A similar situation 

 occurs in the gobiid Trypauchen, where a single long-based dor- 

 sal fin is present. 



The kraemariids appear closest to gobiids. Whether the group 

 will remain a family is uncertain, since the group shows some 

 similarity to the gobiid Parkraemaria. 



Since no immediate sister group has been postulated for go- 

 bioid fishes, relationships of the more primitive groups are un- 

 clear. Miller (1973) and Springer (1983) have recognized only 

 two gobioid families, Rhyacichthyidae and Gobiidae. Springer 

 (1983) has suggested that the Rhyacichthyidae represents the 

 primitive sister group of all gobioid fishes. It is clear that Rhy- 

 acicithys is more primitive than any other known gobioid (al- 

 though arguably only marginally more primitive than some eleo- 

 tridid genera, such as Micropercops), and at the same time 

 specialized. However, eleotridids do not show obvious inno- 

 vative specializations in relation to Rhyacichthys, but show loss 

 of some primitive features. Until a proposed phylogeny of prim- 

 itive genera becomes available, the eleotridids can only be re- 

 garded as a primitive stock, which gave rise to one or more lines 

 leading to the families recognized here. While most eleotridid 

 genera may well have evolved before the xenisthmid-micro- 



