Typhlotanais mimosis, Błażewicz-Paszkowycz, 2007

Błażewicz-Paszkowycz, Magdalena, 2007, Figure 6. Typhlotanais Compactus, Female A In Family Nototanaidae Sieg, 1976 And Typhlotanaidae Sieg, 1984, Zootaxa 1598, pp. 1-141 : 112-116

Typhlotanais mimosis n. sp.

( Figs 65–67 )

Material examined: Holotype: female ( K 41420 ), ANT XXII-3 , PS 67/59-5-E, 67°29.74'– 67°29.61'S, 0°01.93'– 0°02.19'W, depth 4655– 4655 m, epibenthic sledge, 14 Feb 2005 . Paratypes: three females (two dissected on slides) ( K 41421 ), ANT XXII-3 , PS 121-11-E, 63°37.73'– 63°37.55'S, 50°38.09'– 50°38.37'W, depth 2663– 2659 m, epibenthic sledge, 15 Mar 2005 .

Diagnosis: Carapace narrow (1.85 times as long as wide). Cheliped slender, carpus over three times as long as wide, propodus shorter than carpus. Pereopods 1–3 coxa with projection; pereopod-1 merus and carpus about three times as long as wide; pereopod propodus 2–3 with strong seta on dorsal margin.

Etymology: Mimosa is one of four stars in the constellation of ‘The Southern Cross’.

Description: Ovigerous female length 1.8 mm ( Fig. 65A,B ), body long, 8.3 times as long as wide. Carapace 1.8 times as long as wide, almost as long as pereonites 1 and 2 combined, 20% of total body length. All pereonites rectangular, with lateral margin slightly rounded; pereonite-2 almost 1.5 times as long as pereonite- 1; pereonites 2 and 4 subequal; pereonite-3 slightly longer than pereonite-2, as long as wide; pereonite-5 1.25 times as wide as long; pereonite-6 shortest, over twice wider than long, pleon as long as carapace; pleonites 1– 5 subequal; pleotelson with well-developed distal process.

Antennule ( Fig. 66A ): Article-1 over three times as long as wide, longer than articles 2 and 3 combined, with one medial seta and one simple and two pinnate setae distally; article-2 with one short distal seta; article- 3 three times as long as article-2, with two short and three long setae distally.

Antenna ( Fig. 66B ): Article-2 a little longer than article-3, with two setae almost as long as article-3; article-3 with one seta distally; article-4 1.6 times as long as article-5, with one seta distally, article-6 short with one short and three long setae distally.

Mouth parts: Labrum lost during dissection. Mandible ( Figs 66C, D ) stout; molar process well-developed, with well-calcified distal margin supported with tubercle-like structures; lacinia mobilis well-developed, crenulated. Maxillule ( Fig. 66E ) endite with eight apical spiniform setae, with numerous delicate setae along margins; palp lost during dissection. Maxilla lost during dissection. Both lobes of labium ( Fig. 66F ) poorly separated, setose in distal parts. Maxilliped ( Fig. 66G ): basis longer than wide, with short seta on distal margin; endites distal margin with two tubercles and one seta in disto-lateral corner; palp four-articled: article- 1 naked; article-2 wedge-shaped, with three setae on inner margin and one small seta on outer margin; article- 3 with three simple setae on inner margin; article-4 slender (over twice as long as wide), with one simple seta on outer margin and five (two bipinnate and three simple) terminal setae.

Cheliped ( Fig. 66H ): Basis 2.5 times as long as wide; merus wedge-shaped, with one short seta ventrally; carpus over three times as long as broad, with two dorsal setae and with two short setae ventrally; propodus and fixed finger shorter than carpus, over three times as long as wide; fixed finger with three teeth and three setae on inner margin and two rod setae on ventral margin.

Pereopod-1 ( Fig. 67A ): Slender (walking type); coxa with spur tipped with strong seta; basis as long as carpus and propodus combined, with two setae; ischium with simple seta; merus and carpus subequal, with one distal seta; carpus with five short setae; propodus with short subdistal seta ventrally and three subdistal seta dorsally; dactylus a little shorter than unguis; dactylus and unguis combined almost as long as propodus.

Pereopod-2 ( Fig. 67B ): Slender (walking type); coxa with spur tipped with strong seta; basis as long as merus, carpus and propodus combined, with two setae along article; ischium with simple seta; merus and carpus subequal, with two ventro-distal setae; carpus with three short simple setae and one spiniform seta distally; propodus with one spiniform, subdistal seta ventrally and strong seta dorsally reaching end of dactylus; dactylus little shorter than unguis, with one seta; dactylus and unguis combined about half as long as propodus.

Pereopod-3 ( Fig. 67C ): Similar to pereopod-2, but merus with one simple and one spiniform setae.

Pereopod-4 ( Fig. 67D ): Clinging type; basis with one seta dorsally; ischium without seta; merus with two spiniform setae; carpus with spiniform hooks and one dorso-distal seta, prickly tubercles, as long as carpus; propodus four times as long as wide, with two spiniform ventro-distal setae and with distal setae just reaching half of dactylus; unguis simple; unguis and dactylus almost as long as propodus.

Pereopod-5 ( Fig. 67E ): Similar to pereopod-4, but basis ventral margin with simple and pinnate setae, propodus with pinnate seta on dorsal margin.

Pereopod-6 ( Fig. 67F ): Similar to pereopod-4, but propodus with three distal setae as long as half of propodus.

Pleopods 1-5 ( Fig. 67G ): Basal article naked; exopod with eight plumose setae on outer margin and one seta on inner margin; endopod with eleven pinnate setae on outer margin. Gap between most proximal seta and the other setae in both rami.

Uropod ( Fig. 67H ): Endopod two-articled; proximal article less than twice as long as distal article, with one distal seta; exopod two-articled, longer than endopod proximal article; proximal article as long as half of distal article, with one subdistal seta.

Distribution: The species is known from two localities in the Southern Ocean: North of Martha Coast and between the tip of the Antarctic Peninsula and South Orkney Island, at depths of 2659–4655 m.

Remarks: T. mimosis n. sp. can be distinguished from all typhlotanaids by two long proximall setae on pereonite 1. From T. mixtus that is puitative congeneris species, it differs having relative long carapace that is almost twice as long as wide (only 1.5 as long as wide in T. mixtus ). The well developed spur on basis of pereopods 1–3 in the new species is character commonly observed in “greenwichenis” group. The lack of the minute setation along cheliped carpus and large prickly tubercles in pereopods 4–6 of the new species exclude it from “greeenwichensis” group. At the persent stage of knowledge it is assumed that some features (e.g. spur on basis) are consistent within particular morpho-group while can vary within the others groups. A new look on this question could bring a description of more new species while a phylogenetic analysis would test a real realation between ‘mixtus’ and ‘greenwichensis’ group.

Figures

FIGURE 65. Typhlotanais mimosis n. sp., holotype, female. A) dorsal view; B) lateral view. Scale 0.1 mm.

FIGURE 66. Typhlotanais mimosis n. sp., female paratype. A) Antennule; B) Antenna; C) Left mandible; D) Right mandible; E) Maxillule; F) Labium; G) Maxilliped; H) Cheliped. Scale: A, B, H = 0.1 mm, C–G = 0.01 mm.

FIGURE 67. Typhlotanais mimosis n. sp., female paratype. A) Pereopod-1; B) Pereopod-2; C) Pereopod-3; D) Pereopod-4; E) Pereopod-5; F) Pereopod-6; G) Pleopod; H) Uropod. Scale = 0.1 mm.