Peraeospinosus emergensis, Błażewicz-Paszkowycz, 2005

Błażewicz-Paszkowycz, Magdalena, 2005, Revision of the genus Peraeospinosus Sieg, 1986 (Crustacea: Peracarida: Tanaidacea), Journal of Natural History 39 (45), pp. 3847-3901 : 3879-3883

Peraeospinosus emergensis n. sp.

( Figures 15 , 16 )

Material examined Holotype: non-ovigerous ♀, USNM 306701 , Ross Sea, Eltanin 51, Sta. 5761, 76 ° 51.59–

76 ° 01.69S, 179 ° 49.99– 179 ° 53.59E, depth 388– 399 m. One non-ovigerous ♀ paratype, length 9.8 mm, USNM 306700 , Eltanin 51, Sta. 5762, 76 ° 02.19 – 76 ° 02.39S, 179 ° 57.09– 179 ° 51.19E, depth 347–358 m; three non-ovigerous ♀♀, USNM 000000, one dissected on slides, USNM 1082152 , Ross Sea, Eltanin 51, Sta. 5761, 76 ° 51.59 – 76 ° 01.69S, 179 ° 49.99– 179 ° 53.59E, depth 388–399 m; three non-ovigerous ♀♀, USNM 306700 , Ross Sea, Eltanin 51, Sta. 5762, 76 ° 02.19 – 76 ° 02.39S, 179 ° 57.09– 179 ° 51.19E, depth 347–358 m; one nonovigerous ♀, two mancas, USNM 306703 , Ross Sea, Eltanin 51, Sta. 5761, 76 ° 51.59 – 76 ° 01.69S, 179 ° 49.99– 179 ° 53.59E, depth 388–399 m; one non-ovigerous ♀, one manca, USNM 306704 , Eltanin 51, Sta. 5762, 76 ° 02.19 – 76 ° 02.39S, 179 ° 57.09– 179 ° 51.19E, depth 347–358 m; seven non-ovigerous ♀♀, two mancas, USNM 306702 , Eltanin 51, Sta. 5762, 76 ° 02.19 – 76 ° 02.39S, 179 ° 57.09– 179 ° 51.19E, depth 347– 358 m.

Etymology

Named according to the phenomenon of ‘‘polar emergence’’ that is observed for the genus Peraeospinosus .

Diagnosis

Female. Carapace rounded, swollen, little longer than wide. Pereonites 2–5 rectangular and narrowed in middle. Pereonite 1 relatively long (two-thirds length of carapace). Pereonite 6 with rounded margins. Pleon shorter than carapace, pleotelson rectangular. Antennule article 3 only two times as long as article 2. Pereopod 1 carpus with long calceolus on distodorsal corner ( Figure 15A ). Pereopod 2 propodus long (length: width ratio about 8). Pereopod 6 propodus distal setae not longer than dactylus. Uropod rami subequal.

Description

Female without oostegites, holotype, length 11.3 mm ( Figures 15 , 16 ).

Body. Body about 10 times as long as wide.

Cephalothorax. Smooth, rounded, swollen, little longer than wide, rostrum pointed.

Pereonites. Pereonites 2–5 rectangular, with only slightly rounded corners; pereonite 6 with rounded margins in lateral view.

Pleon. All pleonites similar in size; pleotelson rectangular; caudal projection distinctive.

Antennule ( Figure 15B ). Article 1 massive, about twice as long as articles 2 and 3 combined, with three groups of simple and pinnate setae; article 2 half length of article 3, with one pinnate seta and two rod setae; article 3 with five simple apical setae.

Antenna ( Figure 15C ). Articles 1–3 subequal; article 4 twice as long as article 5, with three minute distal setae; article 5 with one simple seta distally; article 6 very short with five terminal setae.

Mouthparts. Labrum hood-shaped, covered by numerous short needle-like setae (not drawn). Mandible ( Figure 15D, E ) robust, molar process well-developed with margins covered by numerous teeth, incisor sharp, lacinia mobilis well-developed, crenulated. Maxillule ( Figure 15F ) endite as long as palp, with nine apical spiniform setae (two of them fused together); palp with two pinnate setae, one longer than the other. Maxilla hemispherical, smooth.

Maxillipeds ( Figure 15G ). Basis fused in heart-shaped plate, with plumose seta on distal margin; endite with two setae and two tubercles distally; palp article 1 unarmed, second wedge-shaped, with three plumose setae on inner margin and one minute seta on outer margin; article 3 trapezoidal, with three setae on inner margin and one simple seta on outer margin; article 4 more slender than the others, with one simple seta in outer margin and five plumose terminal setae.

Cheliped ( Figure 15H ). Basis robust, slightly rounded, 1.5 times as long as wide, fused with the body; merus rectangular with one seta ventrally; carpus with rounded dorsal margin armed with two setae on ventral margin and row of 11 minute setae on dorsal margin; propodus with seta on inner side; fixed finger (propodus projection) tipped with a strong spine, with two to three teeth and three setae on dorsal margin, two setae on ventral margin; one seta near insertion of dactylus; dactylus slightly curved, with minute seta on dorsal margin.

Pereopod 1 ( Figure 16A ). Basis smooth, with two pinnate setae in proximal part only, longer than ischium, merus, and carpus together; ischium short, naked; merus subequal to propodus, with two simple setae and one rod seta distally; carpus with two setae and one long rod seta distally; propodus with one calceolus and two setae, propodus length: width ratio 6.25; dactylus as long as unguis.

Pereopod 2 ( Figure 16B ). Basis almost equal to the rest of articles combined, with two minute setae on ventral margin; ischium short, naked; merus and carpus subequal, both with one spiniform seta distally; additionally two simple setae on merus and three simple and one pinnate seta on carpus; propodus as long as merus and carpus combined, with one short simple seta and one spiniform seta distally; propodus length: width ratio 7.7; dactylus with one simple seta, tipped by subequal unguis.

Pereopod 3 ( Figure 16C ). Similar to pereopod 2.

ereopod 4 ( Figure 16D ). Basis wide, twice as long as wide and a little shorter than total length of carpus and propodus combined, with four pinnate and three simple setae; ischium with one seta; merus subequal to carpus; carpus with prickly tubercle surrounded by short, blunt and calcified spines, two distal hooks and one spiniform seta distally; propodus twice as long as carpus, with one middle seta; in distal part of propodus one long seta and two spiniform setae ventrally; dactylus tipped by relatively short bifurcated unguis.

Pereopod 5 ( Figure 16E ). Similar to pereopod 4 except for two additional spiniform setae on merus.

Pereopod 6 ( Figure 16F ). Similar to pereopod 5; basis unarmed; ischium with two minute setae; propodus tipped by three relatively short terminal setae.

Pleopods ( Figure 16G ). All pleopods similar in structure; exopod and endopod with a row of plumose setae on outer margin (length: width ratio of exopod 3.1; of endopod 3.4); the most proximal seta on the exopod and endopod, separated from remainder by a gap; one plumose seta on inner margin of endopod.

Uropod ( Figure 16I ). Both rami uni-articled, subequal, three times as long as basal article; endopod with two pinnate setae at the middle, tipped by four simple terminal setae and two pinnate setae; exopod with short simple seta in distal in proximal part of outer margin, tipped by one strong seta and one minute simple seta.

Distribution

Ross Sea, Victoria Land, Pennel Bank (Antarctic) at the depth range of 347–399 m ( Figure 25 ).

Remarks

Peraeospinosus emergensis n. sp. is distinguished by the presence of long calceoli on the distodorsal corner of pereopod 1 (a character easily seen also in small specimens). It is also characterized by a long merus, carpus (about twice as long as wide), and propodus (eight times as long as wide) of pereopod 2. The other members of the genus Peraeospinosus have carpus and merus as long as wide, and propodus 4.5–6 times as long as wide. Pereonites 2–4 long and rectangular, narrowed in the middle is a character shared by P. emergensis n. sp., P. magnificus , and P. exiliremis n. sp., but P. magnificus has an oval carapace (longer than pereonite 1) and P. exiliremis has a pleotelson much narrower than the pereon, and the uropod exopod a little longer than the endopod. The sixth pereonite is smooth and has rounded margins in dorsal view.

Figures

Figure 15. Peraeospinosus emergensis n. sp., female. (A) Female dorsal view; (B) antennule; (C) antenna; (D) left mandible; (E) incisor of right mandible; (F) maxillule; (F9) tip of maxillule; (G) maxilliped; (G9) details of maxilliped endite; (H) cheliped; (H9) details of cheliped propodus and dactylus; (I) uropod. Scale bar: 1.0 mm (A); 0.1 mm (B–I).

Figure 16. Peraeospinosus emergensis n. sp., female. (A–F) Pereopods 1–6, respectively; (G) pleopod. Scale bar: 0.1 mm.

Figure 25. Distribution of genus Peraeospinosus based on Beddard (1886a, 1886b), Kudinova-Pasternak (1966, 1969, 1990), Lang (1968), and Shiino (1978).