Sub Antarctic waters
Caprellid, “Ghost” or “Skeleton” shrimps, so called for their skeletal appearance. Amphipod crustaceans, easily distinguished by the elongate stick-like body form and reduction of the abdominal appendages. Head is generally fused with pereonite 1. Pereopods on first 2 segments (pereonites) are most flexible and called gnathopods; gnathopods 2 being the largest, used in defense, feeding and substrate attachment. In many species pereopods 3 and 4 may also be reduced or absent. Gills on pereonites 3 + 4, rarely on pereonite 2. Pereopods 5 - 7 much smaller than 1 + 2, used for clinging to the substratum. In females, brood plates (öostegites) develop on pereonites 3 + 4. Much remains to be learnt about their biology, ecology and in many cases changing distributions.
“Pseudoprotomina hedgpethi, new species
Distribution. Type locality: 41°41'S, 59°19'W. Other records: Off east coast of South America and South Orkney Islands. Depth range: 71-403 meters.
Diagnosis. Flagellum of antenna 2 with 2 or 3 articles, male abdomen with anterior pair of papillalike appendages and 2 pairs of biarticulate appendages.
Material examined.
Verna, cruise 14: Sta. 5, 45°51'S, 61°52W, February 3, 1958, 107 meters, 25+ paratypes AMNH 1.3140. Sta. 6, 46°47.7'S, 62°47'W, February 4, 1958, 105 meters, 25+ paratypes AMINII 13141. Sta. 14, 54°23'S, 65°35'W, February 19, 1958, 75 meters, 25+ paratypes AMNH 13142.
Verna, cruise 17: Sta. 74, 41°27'S, 59°33V, May 23, 1961, 71 meters, 25+ paratypes AMNH 13143. Sta. 75, 41°41'S, 59°19'W, May 23, 1961, 82 meters, 1 ♂ holotype AMNH 13144, 92 ♂♂, 62 ♀♀ paratypes AMNH 13145. Sta. 76, 41°57'S, 59°03W, May 23, 1961, 81 meters, 5 ♂♂, 1 ♀ paratype AMNH 13146. Sta. 88, 45°11'S, 60°55'W, June 11, 1961, 110 meters, 1 ♂ paratype AMNH 13147. Sta. 89, 45°02'S, 61°18W, June 11, 1961, 102 meters, 50+ paratypes AMNH 13148. Sta. 90, 44°53'S, 61°43'W, June 11, 1961, 99 meters, 6 ♂♂, 3 ♀♀ paratypes AMNH 13149. Sta. 91, 44°45'S, 62°11'W, June 11, 1961, 98 meters, 1 ♂ paratype AMNH 13150. Sta. 102, 34°25'S, 52°19'W, June 27, 1961, 73 meters, 100+ paratypes AMNH 13151.
Eltanin, cruise 12: Sta. 1082, 60°50'S, 42°55'W, April 14, 1964, 293-311 meters, 1 ♀ paratypes USNM 123753. Sta. 1084, 60°22'S, 46°50'W, April 15, 1964, 293-403 meters, 1 juvenile ♀ paratype USNM 123752.
Description. Male holotype: Body smooth. Length 13.5 min. Antenna 1 approximately 2/3 body length, flagellum with 12 articles. Antenna 2 sparsely setose, flagellum with 2 articles. Setal formula for terminal article of mandibular palp 1-7-1. Mandibles with incisor, lacinia mobilis, several accessory plates; setal row of right mandible with 3 small and 2 large spines, that of left with 7 small and 2 large; molar absent. Pa1p of maxilla 1 with 9 apical and 3 subapical setae, outer lobe with 5 apical spines. Lobes of maxilla 2 with 5 or 6 apical setae. Outer lobe of maxilliped with 8 or 9 marginal setae, margin only slightly serrate; inner lobe with 3 large apical spines; pall) not distinctive, inner distal margins of articles 2 and 3 setose. Propodus of gnathopod 1 subtriangular, grasping margin with 5 proximal grasping spines, palm not serrate but with distinct row of short paired spines; dactylus not serrate. Propodus of gnathopod 2 inflated at midlength with spine notch at approximately 1/2 length, grasping margin with row of short paired spines. Gills elongate, subelliptical. Pereopods 3 and 4 long, propodus with only few small distal setae, dactylus long and approximately equal in length to propodus. Pereopod 5 shorter than 3 and 4, terminal article dactyliform. Abdomen with 2 pairs of biarticulate appendages and anterior pair of small papillalike appendages, penes lateral.
Remarks. The holotype is a small adult male. Although not the largest male in our collection, it was chosen because some larger males show the same inflation and collapsing of the palm of gnathopod 2 as is common in Phtisica marina. The largest male in our collection measured 15.3 mm and agreed closely with the holotype except that the spine notch on the propodus of gnathopod 2 is more proximal and the spines on the outer lobe of maxilla 1 appeared to be degenerate. The largest female, 8.1 mm, resembles the holotype except that the flagellum of antenna 2 consists of 3 articles and lacks the typically male papillalike appendages on the abdomen hut instead has a raised projection. The outer lobe of maxilla 1 of the largest female showed the same degenerate condition as the largest male. The smallest ovigerous female measured 7 mm and agreed with the largest female except that the outer lobe of maxilla 1 bore 6 well-developed spines.
There was considerable variation in the spination of the grasping margin of the propodus of pereopods 3 and 4. Some large males had up to 6 large spines along with several setae, while smaller males and females had nearly smooth grasping margins. The setal formula for the terminal article of the mandibular palp varied from 1-1-1 to 1-7-1. The mandible of the larger males bore an incisor, lacinia mobilis, itp to 2 accessory plates, and up to 9 spines in the setal row. In smaller specimens the incisor, lacinia mobilis, arid the accessory plates were developed; but the setal row varied and in one case appeared to be absent.
Pseudoprotominta Iredgpethi differs from P. hurleyi McCain, 1969, the only other species of this genus in that in the former the flagellum of antenna 2 consists of 2 or 3 articles and in the latter, 4 articles. The other main difference between the species is that the males of P. hedgpethi bear small papillalike appendages in the anterior portion of the abdomen that are lacking in P. hurleyi. These papillalike appendages, reminiscent of the third pair of appendages of Phtisica marina, emphasize the close relationship of Phtisica and Pseudoprotomima.
The specific name is in honor of Dr. Joel W. Hedgpeth, Director of the Yaquina Marine Biological Laboratory of Oregon State University, in gratitude for his enthusiastic support of this project.”
(McCain and Gray, 1971: 133-135)
