FISHERY BULLETIN: VOL. 73, NO. 4 



median lobe, attachment area distinguishable to 

 level of elongate projection of external lobe. In- 

 ternal lobe undivided, bearing rigid hooks con- 

 tinuous with row of cincinnuni, holding two halves 

 of petasma together. The accessory lobe develops 

 early in the juvenile stage (Figure 3i, j, k) and 

 together with characteristic spination of telson 

 and presence of podobranchs behind second max- 

 illiped, young of this species were discernable to a 

 size of 6 mm c.l. (the smallest size captured). 



Thelycum (Figure 31) with plate on eighth 

 thoracic sternite pentagonal, with anteriormost 

 angle concave, anterolateral margin bearing long 

 spines (this plate exhibits greatest variation dur- 

 ing growth, being more rectangular in young 

 females, changing to the pentagonal shape of ma- 

 turity but becoming almost bilobed in very large 

 females). Plate of seventh thoracic sternite bear- 

 ing three anterior directed projections; lateral 

 pair, shortest, bearing short spines; center projec- 

 tion exhibits varying amount of concavity after 

 maturity such that distolateral margins may ap- 

 pear as raised wings. Elevated plate on sixth 

 thoracic sternite triangular and inverted "V" 

 shaped, with apex pointing anteriorly; apex not 

 reaching anterior limit of sternite. Sperm recep- 

 tacles located toward lateral edges near bases of 

 inverted V. 



Coloration at time of capture varying from deep 

 red over entire body to medium red on 

 cephalothorax and lighter on abdomen. Black pig- 

 ment fleck on distolateral edge of ocular peduncle 

 just below corneal region (Figure 2a). Other small 

 flecks of purple pigmentation often observed on 

 carpus and propodus of third maxilliped and first 

 and second pereiopods, on carpus of third 

 pereiopod, and on ventral surface of abdominal 

 somites just anterior to lateral edge of base of each 

 pleopod. 



/Jemarfcs. -Burkenroad (1936) proposed the genus 

 Bentheogennema for those species of Gennadas 

 Bate which possesses podobranchs on the second 

 maxilliped to third pereiopods inclusive. Other 

 generic characters he included were: arthrobranch 

 of first maxilliped large and richly plumose; 

 exopod of first maxilliped without a constricted, 

 segmented distal portion; dorsal carina on sixth 

 abdominal somite only; telson with truncated apex 

 and more than a single pair of mobile lateral 

 spinules. 

 As is often the case, the addition of a new 



species changes the generic formula for that 

 group. The new species is similar to Gennadas in 

 the armature of the telson but more closely 

 resembles Bentheogennema with podobranchs on 

 the second maxilliped through third pereiopod. We 

 agree with Kemp (1909) and Burkenroad (1936) 

 that the presence of podobranchs, a primitive 

 characteristic, is a more important generic trait 

 than the number of pairs of spines on the telson. 



We found that the two species of Bentheogen- 

 nema— B. borealis (Rathbun) and B. burkenroadi 

 n. sp.— from the Oregon coast lack the large, richly 

 plumose arthrobranch on the first maxilliped that 

 Burkenroad (1936) included as a generic 

 characteristic. Both have small rudimentary 

 arthrobranchs similar to Gennadas. We assume 

 that Burkenroad (1936) did not have samples of B. 

 borealis but included this arthrobranch structure 

 as a generic characteristic from samples of B. in- 

 termedium (Bate) and B. pasithea (Man). 



Although Tirmizi (1959) stated that the endopod 

 of the first maxilliped is five-segmented in Gen- 

 nadas and apparently only four-segmented in 

 Bentheogennema, we have found that Gennadas 

 propinquus Rathbun off the Oregon coast has a 

 four-segmented endopod. Hence these characters 

 are not reliable to distinguish these two genera. 



Bentheogennema burkenroadi can be separated 

 from B. borealis, B. intermedium, B. pasithea, and 

 B. stephenseni (Burkenroad) by the armature of 

 the telson, and the structures of the petasma and 

 thelycum. The telson of B. burkenroadi typically 

 possesses only a single pair of terminal-lateral 

 spines, whereas the other members of this genus 

 possess two or more pairs of lateral spines: B. 

 borealis and B. stephenseni two pairs; B. pasithea 

 three pairs; B. intermedium (as described by Tir- 

 mizi 1959) four pairs. The number of spines 

 present on the telson should not be held as an 

 invariable characteristic, there is undoubtedly a 

 small percentage of variation as exemplified by 

 the two males of B. burkenroadi (USNM 150839, 

 150840) which possess two pairs of terminal spines. 

 It is possible that one of the two specimens of 

 Gennadas calmani (Kemp) (synonymy: B. 

 borealis), which Kemp (1909) illustrated with two 

 pairs of terminal spines is also an example of such 

 variation. 



The petasma of this new species is unique and 

 easily distinguishable from that of other members 

 of the genus. The combined structures of the ac- 

 cessory lobe with its mode of attachment, its large 



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