ALLEN: GOBIESOCIFORMES 

 Table 167. Extended. 



631 



each species exhibit a unique distribution of melanophores with- 

 in and among these regions (Table 167). The distribution of 

 melanophores within regions can be coded. For example, Con- 

 idcns laticephalus has a pigment pattern which can be designated 

 as the followmg: DH5, DT6-10, LT3-7, DGl 1-15. LGO, VGl 1- 

 14, PV4-5. Trachelochismus melohesia by the same process is 

 designated as: DHO, DTO, LTO, DG26-35, LGO, VGO, DV5- 

 9. If adopted, this system of coding pigment patterns will serve 

 two purposes. It will greatly aid identification of clingfish larvae 

 and will also lead to more comparable descriptions of gobiesocid 

 larvae in the future. 



Pigment patterns do not appear to be related to phylogenetic 

 hypotheses based on adult characteristics. In virtually all known 

 cases closely related species (subfamilial levels) tend to have 

 noticeably different patterns and often range from heavily to 

 lightly pigmented (Table 167). Within the Trachelochisminae, 

 Conidcns laticephalus is heavily pigmented while both Tra- 

 chelochismus melohesia and T. pinnulala are lightly pigmented. 

 The same pattern is exhibited in all other subfamilies (Table 

 167) especially the Lepadogastrinae and Gobiesocinae (partic- 

 ularly in the genus Gobiesox). Members of subfamilies often 

 overlap in their distributions (Briggs, 1955). Diverse pigment 

 patterns among closely related, sympatric clingfish larvae may 

 well represent ecotypic variation. Heavily pigmented larvae often 

 live in surface waters where the pigmentation may protect them 

 against solar radiation or serve as protective coloration (Moser, 

 1 98 1 ). Less pigmentation may indicate that the larvae normally 

 occur deeper in the water column where irradiance does not 

 present problems for development. 



Only a few published descriptions included myomere counts. 

 Those accounts which did revealed a range from 24 up to 37 

 (Table 167). The number of myomeres appears to have great 

 diagnostic value in some cases when used in conjunction with 

 pigment, i.e., among the species of Gobiesox (Table 167). The 

 lack of myomere count data among the described gobiesocid 

 larvae may, in part, be due to the difficulty in countmg caused 



by heavy trunk pigmentation. Nonetheless, it is unfortunate that 

 this important character has not received greater attention es- 

 pecially since vertebral counts are not available for many species. 

 Adult characteristics which are valuable for identifying older 

 larvae are also included in Table 168. 



The most distinctive characteristic of clingfishes is the suction 

 disc which is supported by the pelvic fins and distal postcleithra 

 of the pectoral girdle. The two types of discs are found in go- 

 biesocids. The "double" disc has a small, posterior disc with a 

 free anterior margin separating it from an anterior disc. In the 

 "single" disc the anterior and posterior portions are coalesced 

 into one continuous structure (Briggs, 1955). The onset of suc- 

 tion disc development occurs fairly early in larval development 

 (ranges from 4.5 to 8.0 mm SL) and appears to be closely allied 

 to time of notochord flexion in most species (Table 167). Disc 

 development does not appear to differ appreciably between sin- 

 gle and double disc types except that in the single type a con- 

 sistent connection remains between the anterior and posterior 

 elements throughout development (Fig. 339). The completion 

 of the suction disc is undoubtedly critical in late larval stages. 

 Settlement seems unlikely to occur without a functional disc. 



Specialized glandular tissues appear on the body surface and 

 out onto the finfolds in several species of gobiesocids (Shiogaki 

 and Dotsu, 1971b; Allen and Ilg, 1983). Although these struc- 

 tures are not specifically mentioned in other descriptions, illus- 

 trations of larvae from some of these studies include structures 

 in the finfolds which may be these same glandular tissues. Fur- 

 ther studies are needed to ascertain the extent of this special- 

 ization within the Gobiesocidae and the possible function of 

 these tissues. 



Relationships 



The systematic relationships among the Gobiesocidae were 

 addressed, as previously mentioned, by Briggs (1955). His eight 

 subfamilies reflected both morphological similarities and zoo- 

 geographic distributions (subfamilies occupy fairly distinct re- 



