PEREZ EARFANTE: AMERICAN SOLENOCERID SHRIMPS 



FIGURE 7. — Hymenopenaeus debilis, 9 15.5 mm cl, Dominica 

 Island, Lesser Antilles. Thelycum, ventral view. 



Thelycum (Figure 7) with median protuberance 

 on sternite XIV pyriform, strongly produced 

 anteriorly into acute, freely projecting apical 

 portion overlapping, and closely appressed to, 

 sternite XIII; latter bearing paired subtriangular 

 elevations with bases raised in horizontal ridges 

 flanking tip of protuberance on sternite XIV; 

 anterior part of sternite XIII with setose trans- 

 verse prominence; sternite XII bearing pair of 

 large, setose, posterolateral horns reaching or 

 slightly surpassing midlength of sternite XIII. 



Photophores.-Six present on sternum: pair in 

 elevated posterior margin of sternite XIII, just 

 mesial to coxae of fourth pereopods; pair between 

 second pleopods; single one between bases of 

 fourth pereopods, and another between bases of 

 fifth pleopods. Details of their structure given by 

 Burkenroad (1936). 



Co/or.-Bouvier (1908) on the basis of a water 

 color illustration made at the moment of capture 

 stated that the color is "d'un rouge-orange presque 

 uniform." Burkenroad (1936) described fresh 

 material as "transparent, speckled with minute 

 scarlet chromatophores which were concentrated 



at the bases of the pleopods and uropods and at the 

 tip of the telson. The ocular peduncle at the base of 

 the cornea, the mouthparts, and the tip of the 

 second maxillipede were scarlet. The stomach was 

 red, the pleonic gut and nerve-cord orange; the 

 gastric gland brownish, the ovary creamy (as seen 

 through the overlying tissues). The eyes were 

 reddish brown." 



Maximum size-Males, 55 mm tl; females, 78 mm 

 tl (Bouvier 1908). Largest specimens examined by 

 me: males 15.5 mm cl, 52 mm tl; females, 19.5 mm 

 cl, 75 mm tl. 



Geographic and bathymetric ranges-Western 

 Atlantic: from Hudson Canyon, New Jersey 

 (39°55'N, 70°31'W) through the Gulf of Mexico 

 and Caribbean Sea to Guyana (08°14'N, 57°38'W). 

 Eastern Atlantic: Azores Islands and northwest 

 Africa — from Cap Spartel, Morocco, to Cape 

 Verde Islands, including Canary Islands (Figure 

 8). It has been found at depths (Figure 9) between 

 300 and 2,163 m (latter in Bouvier 1908). 



Affinities -Hymenopenaeus debilis closely resem- 

 bles H. aphoticus, but differs from it in that the 

 rostrum is usually armed with ventral teeth (only 

 3% of the specimens examined by me lack such 

 teeth), and the sternum bears six photophores 

 which are absent in H. aphoticus. The cornea is 

 subreniform, and it is disposed such that its prox- 

 imal margin is oblique to the basal margin of the 

 ocular peduncle and an imaginary line extending 

 from the medial tubercle parallel to the basal 

 margin of the peduncle crosses its proximolateral 

 extremity. The cornea (actually the entire eye) of 

 H. debilis is also much larger than that of H. 

 aphoticus: its maximum diameter about twice 

 that of the basal margin of the peduncle, and the 

 proportion of the diameter to the carapace length 

 ranges from 15.5 to 22.0, averaging 19.7. Fur- 

 thermore, in males of H. debilis the petasma 

 exhibits larger distal processes than does that of 

 H. aphoticus, but the lateral one is produced 

 proximally in an auricle which is small and 

 unarmed, and the proximomesial spinules on the 

 free margin of the mesial process are only slightly 

 longer than the remaining ones instead of consid- 

 erably so as in//, aphoticus. Finally, the length of 

 the ventrolateral spur borne by the sclerite at the 

 base of the appendices masculina and interna is 

 equivalent to 0.50-0.75 that of the appendix 

 masculina. The thelyca of the two species are 



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