RICHARDSON; CURRENT KNOWLEDGE OF SCULPIN LARVAE 



Table 2. — Groupings of 25 cottid genera reported to occur in the northeast Pacific Ocean between Baja California and the Aleutian 

 Islands based on shared larval characters. Group characteristics were based on representative species for which larvae are known, as 

 listed in Table 1. Also included in the groupings is an unidentified larval type, "Cottoid Type A" of Richardson and Washington (1980) 

 which may represent a new genus. 



Group 



General characteristics 



Genera 



Ungrouped genera 



Multiple preopercular spines, rounded snout, stubby shape, slightly trailing gut, 



sometimes with gut protrusions or diverticula 

 Four preopercular spines, pointed snout, moderately slender, postanal pigment when 



present usually restricted to ventral midline 

 Four principal preopercular spines or none, rounded snout, often globose shape 



with loose skin, pigmented pectoral fins 



Four preopercular spines, rounded snout, relatively deep bodied, ca. 4-5 mm NL at 

 hatching, postanal pigment dorsally, ventrally. and laterally 



Four preopercular spines not pronounced, rounded snout, relatively slender, post- 

 anal pigment dorsally, ventrally, laterally, probably >7 mm NL at hatching, 

 pectoral fins unpigmented or with pigment band near margin 



Four preopercular spines, rounded snout, relatively slender, no additional head 

 spines, postanal pigment restricted to ventral midline 

 Enophrys. Gymnocanthus, Myoxocephalus. Radulinus, Rhamphocottus. Hemitripterus 



Artedius, Clinocottus. Oligocottus. 

 Orthonopias 



Paricelinus , Triglops , Icelus , 

 Chitonotus , Icelinus 



Dasycottus. Psychrolutes, Gilbertidia, 

 '7 Malacocottus . Cottoid Type A (new 

 genus?) 



Scorpaenichthys , Hemilepidotus 

 Blepsias , Nautichthys 



Leptocottus, Cottus 



group and of each ungrouped genus are summa- 

 rized to facilitate recognition and minimize tax- 

 onomic and identification problems involving 

 cottid larvae. These groupings are based on com- 

 plete developmental series to the extent available, 

 but only representative figures illustrating one 

 point on a developmental continuum are pre- 

 sented (Figures 1-9). The groupings are necessar- 

 ily preliminary because not all species in all 

 genera are known as larvae. The groups described 

 below are not arranged in any particular order. 

 Generic designations are used as discussed in the 

 previous section. 



Group 1 



This is the tightest group among the 25 genera. 

 Included are Artedius, Clinocottus, Oligocottus , 

 and tentatively Orthonopias (Figures 1, 2). The 

 unique multiple preopercular spine pattern dis- 

 tinguishes it from all other groups or genera. 

 [Although a complete series of Orthonopias has 

 not been described and the spine pattern is un- 

 knov^Ti, small larvae (Figure 2) are very similar 

 to Artedius in form and pigment characteristics 

 and are tentatively included in this group.] The 

 stubby body shape, rounded snout, and somewhat 

 trailing gut Eire remarkably consistent within the 

 group. Presently, identification to genus based on 

 larval characters is still difficult and in need of 

 better definition. Characters used to distinguish 

 species (besides fin ray counts) include: number, 

 spacing, and shape of ventral midline melano- 

 phores; intensity of gut pigmentation; presence of 

 unusual gut diverticula; total number of preoper- 

 cular spines and position of largest spines; num- 



ber of spines (e.g., none, two, cluster) in the 

 parietal and posttemporal-supracleithral regions; 

 presence or absence of pigment on the nape or 

 head. 



Although the multiple preopercular spine pat- 

 tern persists through the larval period, adults 

 have four preopercular spines with the lower three 

 reduced and the upper variously modified. Rem- 

 nants of the larval serrations have been observed 

 only in adult A. notospilotus (Howe'*). It is unclear 

 which four spines of the larvae persist in adults. 



Group 2 



This is also a rather cohesive group (Figure 3) 

 consisting of slender forms with pointed snouts 

 and four prominent preopercular spines [Paricel- 

 inus, Triglops, Icelus (tentatively), Chitonotus, 

 Icelinus]. This general body shape is remarkably 

 similar among genera and is not found in any 

 other genera considered. All have a relatively 

 short snout to anus distance. Postanal ventral 

 midline pigment is usually present (absent in one 

 species of Triglops) with some additional melano- 

 phores along the caudal fin base. Dorsal midline 

 pigment is usually absent except for a few spots in 

 some Icelinus and possibly a row in some late 

 stage Triglops. Generic differences include degree 

 of gut pigmentation (e.g., darkest in Paricelinus 

 and some Triglops), number and position of ven- 

 tral midline melanophores, and degree of head 

 spination (e.g., postocular spines in Paricelinus 

 and Triglops). 



"K. D. Howe, Ph.D. candidate. Department of Fisheries and 

 Wildlife, Oregon State University, Corvallis, OR 97331, pers. 

 commun. September 1978. 



107 



