DeBrosse et al : Megalopal stages of Cancer oregonensis and C productus 



41 



Abbreviations used in the text are defined as follows: 

 TL: Total leng:th, measured from the tip of the rostrum 

 to the midpoint of the telson; CL: Carapace length, 

 measured from the tip of the rostrum to the posterior 

 midpoint of the carapace. 



Description: Cancer oregonensis Dana 



TL 5.6-6.2 mm, CL 2.5-3.8 mm. 



Carapace (Fig. 2A) Considerably longer than broad, 

 lacking setae; lateral knobs usually absent, but with 

 pair of gastric protuberances. Rostrum well developed. 

 Dorsal spine projecting posteriorly over first two ab- 

 dominal somites. Rostral region broad, with ventro- 

 medial tubercle. Eyes well developed, corneae slight- 

 ly dilated. 



Antennule (Fig I A) Biramous; peduncle 3-seg- 

 mented, proximal segment broadly expanded and with 

 6-14 scattered setae, penultimate segment with 4 or 

 5 submarginal setae distally, ultimate segment with 2 

 or 3 setae. Exopod 4-segmented, basal segment naked, 

 2nd segment with 7-13 aesthetascs, 3rd with 6-9 

 aesthetascs and 2 or 3 submarginal setae, 4th with 3-5 

 aesthetascs, 1 distomarginal seta and 1 terminal seta. 

 Endopod indistinctly 2-segmented, proximal segment 

 naked, distal segment with 2 or 3 marginal and 3 or 

 4 terminal setae. 



Antenna (Fig. IB) Peduncle 3-segmented, flagellum 

 with 8 articles; setal formula varying from 3,2,4,0,0, 

 3,0,3,0,4,3 to 6,3,5,0,1,4,0,5,1,4,4. 



Mandible (Fig. IC) Molar and incisor processes not 

 distinguishable. Mandibular palp 2-segmented, prox- 

 imal segment naked, distal segment with 9-11 mar- 

 ginal setae. 



Maxillule (Figure 1 D) Endopod indistinctly 2-seg- 

 mented, prf)ximal segment with or without 1 marginal 

 seta basally, distal segment with 1 or 2 terminal setae. 

 Coxal endite with 13-16 setae. Basal endite with 23-29 

 total setae/spines including 4 or 5 distinct marginal 

 setae basally. 



Maxilla (Fig. 1 E) Endopod broad basally, with 4-6 

 naked setae on outer margin in proximal half. Coxal 

 endite with 3-6 terminal and 1-3 subterminal plumose 

 setae on proximal lobe, 2-5 terminal and 1-3 subter- 

 minal plumose setae on distal lobe. Basal endite with 

 8-10 terminal and 1 or 2 subterminal plumose setae 

 on proximal lobe and 8-11 terminal and 1 or 2 subter- 

 minal plumose setae on distal lobe. Scaphognathite with 

 68-85 marginal and 4 or 5 scattered surface setae (not 

 shown in illustration). 



First maxilliped (Fig. IF) Epipod with 14-17 mar- 

 ginal or sulimarginal setae. Exopod 2-segmented, 

 proximal segment with 2-4 plumose marginal setae 

 distally, distal segment with 3-6 terminal plumose 

 setae. Endopod 1-segmented with 1-3 marginal setae 

 basally, 3-5 setae distally and 1 short terminal seta. 

 Coxal endite with 15-20 setae. Basal endite with 26-35 

 setae. 



Second maxilliped (Fig. 1G) Epipod with 6-9 mar- 

 ginal setae; protopod with 1-5 setae. Exopod 2-seg- 

 mented, proximal segment with 1 or 2 short marginal 

 spine-like setae, distal segment with 3-5 terminal 

 plumose setae. Endopod 4-segmented, merus with 1-4 

 submarginal setae distally, carpus unarmed or with 1 

 or 2 marginal setae distally, propodus with 6-9 setae 

 distally, dactyl with 8-11 marginal and submarginal 

 setae, some distinctly serrate. 



Third maxilliped (Fig. IH) Epipod with 17-21 mar- 

 ginal setae; protopod with numerous scattered setae 

 on surface. Exopod 2-segniented, proximal segment 

 with 3-5 submarginal setae, distal segment with 4-8 

 terminal plumose setae. Endopod 5-segmented, ischium 

 with inner margin somewhat denticulate, 24-32 mar- 

 ginal and/or submarginal and surface setae, merus with 

 9-13 setae, carpus with 14-19 setae, propodus with 

 12-18 simple and serrate setae, dactyl with 7-9 simple 

 or serrate setae and 1 or 2 distinctly toothed bristles. 



Pereopods (Figs. 2B,C,E-G) Segments of all pereo- 

 pods with scattered short setae. Cheliped with veniral 

 surface of ischium unarmed; cutting edge of fixed 

 finger with 3 or 4 teeth, cutting edge of dactyl with 

 2-4 teeth. Second pereopod with coxa and ischium each 

 armed with acute process on ventrodistal margin (Fig. 

 2D), latter 1/3 size of former; dactyl with 6 or 7 spines 

 on ventral margin. Third, 4th and 5th pereopods lack- 

 ing coxal and ischial processes. Dactyls with 4-8, 5-7 

 and 3 or 4 spines on ventral margins respectively; 

 dactyl of 5th also with 3 terminal setae. 



Abdomen and pleopods (Figs. 2 A, 2H,I) Abdomen 

 6-segmented, segments unarmed. Second through 5th 

 pleopods with 3-5, 4 or 5, 3 or 4, and 4 hooks respec- 

 tively on appendix internae. Exopods with 20-22, 

 19-22, 17-22, and 17-19 plumose setae respectively. 

 Uropods 2-segmented, peduncle with 1 marginal plu- 

 mose seta, exopod with 11-13 plumose setae, endopod 

 absent. 



Telson (Fig. 2J) Dorsal surface with 3 or 4 pairs of 

 short setae in midline distally, terminal margin slight- 

 ly rounded, without marginal setae. 



