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Description

Bathypanoploea schellenbergi n. sp.

 

Iphimediopsis australis Schellenberg, 1931: 127, pl. 1, fig. c (not Acanthonotozoma australis Chilton, 1912). Bathypanoploea australis Schellenberg, 1939: 137 (footnote, by implication).

 

Material. - Swedish Southpolar Expedition 1901-1903, between South Georgia and the Falkland Islands, 28 June 1902, 50° 19' S 50°50' W, 2675 m, 1 ♀with juveniles in brood pouch, 45 mm (holotype; in Swedish Museum of Natural History, Stockholm, Sweden). Paratypes: "Eltanin", Cruise 9, Sta. 684, 25 August 1963, 54°55' S 38°05-07'W, 595-677 m, 1 ♀ with juveniles in brood pouch, 28 mm; Cruise 12, Sta. 997, 14 March 1964, 61 °44-46' S 55°56-54' W, 769 m, l ♂, 50 mm, 1 ♂, 38 mm; Cruise 32, Sta. 2016, 14 January 1968, 73°59'S 176°11'E, 581-586 m, 1 ♀ with juveniles in brood pouch, 50 mm; Cruise 32, Sta. 2085, 1 February 1968, 77°31' S 172°32' W, 468-482 m, 1 ♀ with juveniles in brood pouch, 45 mm; all paratypes deposited in U.S. National Museum of Natural History, Washington, D.C., U.S.A.

 

Diagnosis. - As for genus.

 

Description (,supplementing Schellenberg, 1931). - Strong middorsal carinae present on pereonites 7, pleonites 1-3, and urosomite 1 in most large adults, juveniles from brood pouch with carina only on urosomite 1. Antenna 1 considerably shorter than antenna 2, reaching slightly past end of peduncle article 5 of antenna 2. Antenna 1 article 1 with short mediodorsal tooth, ac- cessory flagellum uniarticulate. Antenna 2, article 5 slightly longer than article 4. Upper lip asymmetrically lobed, nonsetose. Mandible without molar but in- cisor strongly toothed, setal row and accessory plate present on both right and left sides. Palp 3-articulate, article 2 longest, both articles 2 and 3 setose along one margin. Lower lip with inner lobes, distal margin broad, setose, with small, acute projection at outer distal corner. Maxilla 1, palp biarticulate with well-spaced spines distally, one specimen also with short row of finer setae, as in Alexandrella; shape of palp variable but always expanded; outer plate carry- ing 9-11 strong spines distally; inner plate with nonplumose setae medially and on inner face. Maxilla 2 inner plate wider than outer; outer plate without pec- tinate setae, no distinction between distal and medial setae on inner plate, none plumose; inner plate not as medially expanded as in Alexandrella, plate on- ly half as wide as high. Maxilliped outer plate clearly longer than palp, medial margin sparsely spinose; inner plate extends slightly past proximal margin of palp article 1 but not to distal margin; palp 4-articulate, article 4 approximately 80% of article 3. Gnathopods 1 and 2 simple and alike; gnathopod 1 carpus slightly longer than gnathopod 2 carpus, dactyl approximately half as long as propodus. Pereopods 5 and 6, bases slightly expanded, anterior and posterior margins almost parallel, merus and carpus of each subequal, propodus longest. Pereopod 7 basis posterior margin strongly expanded into proximal lobe, excavate below, posterodistal corner subacute, carpus longer than merus but subequal to propodus, dactyl almost as long as propodus. All uropods biramous with minute spines present along lateral margins of rami and pedun- cle. Uropod 1 inner ramus slightly shorter than outer, outer subequal to peduncle. Uropod 2 outer ramus approximately 0.7 inner, both rami longer than peduncle. Uropod 3, peduncle short, rami lanceolate. Telson variably cleft, with spines along lateral and distal margins.

 

Distribution. - South Georgia to South Shetland Islands and Ross Sea; 468-2675 m.

 

Remarks. - Differences with size and sex were noted for both middorsal carinae and overall body shape. Large females with juveniles in their brood pouches exhibited a noticeable enlargement and "humping" of the first four pereonites relative to the head (not in specimen from "Eltanin" Sta. 684). All adult specimens examined had well-developed carinae on pereonite 7 and pleonites 1-3 as well as on urosomite 1, though carinae were less pronounced on smaller specimens. One specimen also had an acute posteriorly-directed tooth on pereonite 6. Juveniles (5-10 mm) removed from the brood pouch lack all but the acute keel on urosomite 1. The shape and proportionate height of the maxilliped outer plate, and the shapes of the maxilla 1 palp and telson were also found to be,variable. The size and shape of the maxilliped outer plate may be subject to geographical variation. The outer plates were proportionately longer relative to the palp in specimens from the Falklands, South Georgia, or South Shetland Island (` `Eltanin" Sta. 684, 997, and type-material) than the outer plates of specimens from the Ross Sea (` `Eltanin" Sta. 2016 and 2085). Differences in the shapes of the maxilla 1 palp and telson appear to be in- dividually variable.

 

Schellenberg (1931) originally considered this species to be identical with Alexandrella australis (Chilton). There are, however, several differences that distinguish it from the genus Alexandrella; the shape and setation of maxilla 2, the setation of the maxilliped, the length of the inner plate and palp article 4 of the maxilliped, and the shape and ornamentation of the telson. In addition, it differs specifically from A. australis in the shape of coxa 5, lack of a prominent mediodorsal tooth on article 1 of antenna 1, form of the upper lip and dentation of the mandible incisor. Bathypanoploea has been retained as the generic designation for the species described by Schellenberg. The specific name australis must refer to Chilton's species, consequently schellenbergi has been chosen to replace it. Schellenberg offered no explanation of the placement of this species in the Acanthonotozomatidae, although he may simply have been following the lead of Chilton, who unfortunately did not examine his specimen's mouthparts. The smoothly rounded distal margins of the first several coxae, the quadrate mouthparts, expanded and setose maxillae and enlarged outer plate of the maxilliped do not suggest this affinity (see also remarks under A. australis).”

 

 

(Holman & Watling, 1983a: 47-52)

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© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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