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Description

"Pasiphaea balssi Burukovsky and Romensky, 1987

 

Figs. 20, 21, and 22

 

Synonymy.

 

Pasiphaea longispina, Balss, 1925, p. 238, fig. 11.

 

Pasiphaea acunfrons, Zarenkov, 1968, p. 156, fig. 1.

 

Pasiphaea balssi Burukovsky and Romensky, 1987, pp. 52, 58 (in key), figs. 1(1-7), 2(9), 4.

 

Material examined. Cruise 46: Sta. 313, one male (CL = 23.4), USNM 256353.

 

Diagnosis. Rostrum long, reaching beyond anterior margin of carapace to beyond posterior margin of cornea, narrowed anteriorly into spinelike extremity, not rising above level of dorsal surface of carapace. Carapace dorsally carinate almost to posterior margin. Branchiostegal spine strong, marginal, noncarinate. Branchiostegal sinus present but not deep. All abdominal somites lacking posterodorsal spine. Abdominal somite 1 dorsally rounded; somites 2-6 dorsally carinate (6 on anterior two-thirds). Somite 6 about 1.6 times length of somite 5 and about 1.2 times length of telson. Telson dorsally sulcate, posterior margin deeply cleft. Pereopod 1 merus armed with 7-8 movable spines on posterior margin; ischium and basis not armed with movable spines. Pereopod 2 merus armed with 16-19 movable spines on posterior margin; ischium armed with 1 movable spine; basis armed with 10 movable spines.

 

Description. Rostrum (Figure 20a) long, reaching beyond anterior margin of carapace to beyond posterior margin of cornea of eye, anteriorly narrowed into spinelike extremity, low, not rising above level of dorsal surface of carapace. Carapace dorsally carinate almost to posterior margin. Lateral surface of carapace with suprabranchial carina. Anterior margin of carapace dorsally produced as prominent convex lobe overreaching first segment of ocular peduncle and about as far as rounded orbital angle; anterior margin continuing ventrally from orbital angle as concave margin to broadly rounded angle above level of branchiostegal spine, anteroventral angle below spine broadly rounded, leading into shallowly concave branchiostegal sinus. Branchiostegal spine strong, marginal, noncarinate.

 

Abdomal somite 1 dorsally rounded; somites 2-6 dorsally carinate (6 on anterior two thirds), all somites lacking posterodorsal spine. Pleuron 1 broadly rounded ventrally; pleuron 2 with somewhat sinuous ventral margin; pleura 3-5 ventrally straight, with rounded lobelike extension anteriorly. Somite 6 about 1.6 times length of somite 5 (measured midlaterally) and about 1.2 times length of telson, with curved lateral ridge. Telson dorsally sulcate, posterior margin deeply cleft (Figure 21h), with 8 pairs of spines, decreasing in length medially (large lateral pair missing).

 

Antenna 1 with stylocerite not reaching distal margin of basal peduncular segment, broadening distally, api­cally acute; segment 2 less than half length of basal seg­ment, somewhat more than half length of segment 3.

 

Antenna 2, scaphocerite reaching beyond peduncle of antenna 1 by less than half its length, tapering distally, outer margin weakly convex, produced into strong distal tooth extending well beyond apex of lamella; peduncle segment 2 bearing strong obliquely directed ventrodistal spine.

 

Mouthparts as illustrated. Maxilliped 3 reaching to distal one fourth of scaphocerite, ultimate segment apically slightly rounded, anterior and posterior margins with single row of long setae; menial surface with dense rows of short setae; penultimate segment 0.6 times length of ultimate segment, with several dense rows of setae on distomesial surface, exopod well developed.

 

All pereopods with well-developed exopods, but no epipods. Pereopod 1 (Figure 21b) reaching beyond scaphocerite by length of fingers of chela; fingers slender, cutting edges toothed, tips curved and capable of crossing each other, 0.6 times length of palm; palm (Figure 21c) with posteromedial row of 10-11 small movable spines and setae; carpus about 0.4 times length of palm; merus 4 times length of carpus, with 7-8 movable spines on posterior margin; posterior margin of ischium and basis not armed with movable spines, posterodistal margin of basis in form of strong spinelike projection.

 

Pereopod 2 (Figure 21d) reaching beyond scaphocerite by fingers and distal one fourth of palm; fingers slender, cutting edges toothed, tips curved and crossing each other, about 0.8 times length of palm; carpus 0.25 times length of palm; merus 6 times length of carpus, with 16-19 movable spines on posterior margin; ischium with 1 movable spine on posterior margin; basis with 10 movable spines on posterior margin, posterodistal margin of basis in form of strong spinelike projection.

 

Pereopod 3 very slender, reaching as far as distal end of pereopod 1.

 

Pereopod 4 shorter than either pereopod 3 or pereopod 5, reaching to distal one fourth of carpus of pereopod 5; dactylus 0.2 times length of propodus, ovate, setose; propodus with several rows of setae on posteromesial surface.

 

Pereopod 5 reaching to midlength of merus of pereopod 2; dactylus distally rounded, with fringe of setae increasing in length distally; carpus about 0.4 times length of propodus.

 

Pleopod 1 with endopod (Figure 21i) somewhat ovate, small rounded lobe bearing tiny hooks on menial margin. Pleopods 2-5 with slender appendix interna distally armed with patch of small hooks; pleopod 2 with appendix masculina (Figure 21j) about 0.5 times length of appendix intema, bearing 7 spines on distal and outer margins.

 

Inner uropodal ramus reaching beyond apex of telson by about 0.3 times its length; outer uropodal ramus reaching beyond inner ramus by 0.25 times its length.

 

Remarks. This specimen appears to agree in most essential details with the description and figures of P. balssi of Burukovsky and Romensky [1987], with the exception of not agreeing with the characteristic used in group IX of their key to members of the genus, i.e., having a rostrum reaching the distal end of the eye. However, it is noted that in their description, the rostrum is described as reaching the middle of the pigmented part of the eye.

 

Distribution. The specimen of P. balssi dealt with here is the first record of the species from Subantarctic waters of the southeastern Indian Ocean south of Australia (Figure 22). The species has previously been collected from Subantarctic waters of the South Atlantic [Burukovsky and Romensky, 1987; Zarenkov, 1968] and Subantarctic waters of the southern Indian Ocean [Balss, 1925]."

 

(Wasmer, 1992)

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© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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