Typhlotanais mixtus Hansen, 1913

Błażewicz-Paszkowycz, Magdalena, 2007, Figure 6. Typhlotanais Compactus, Female A In Family Nototanaidae Sieg, 1976 And Typhlotanaidae Sieg, 1984, Zootaxa 1598, pp. 1-141 : 108-112

Typhlotanais mixtus Hansen, 1913

( Figs 62–64 )

Typhlotanais mixtus: Hansen (1913) 3 (3): 53, 59–61; Nierstrasz (1913) 32 (a): 38; Stephensen (1913) 22: 270, 421;

Stephensen (1932) 6: 350; Stephensen (1936) 80 (2): 29; Lang (1970) 23 (4): 275, 288; Morino (1971) 18 (5): 353. Peraeospinosus mixtus: Sieg (1986a) 45: 156–163; Błażewicz-Paszkowycz & Sekulska-Nalewajko (2004) 27: 224, 226.

Material examined: Syntype: one female, CRU 7351 , Ingolf 125, Arctic, N. of Iceland, 68º08'N, 016º02'W, depth 1373m, 29 Jul 1896 ; Other material: two females (one dissected on slides), BIOICE 2773, Iceland Plateau, 69º24.8'N, 14º27.53'W, depth 1629 m, RP, 3 Aug 1995; bottom temp -0.86ºC, salinity 34.90 ‰.

Diagnosis: Carapace narrow (1.5 times as long as wide). Cheliped carpus 2.5 times as long as wide, propodus as long as carpus. Pereopods 1–3 coxa without projection; pereopod-1 merus and carpus about as wide as long; pereopods 2–3 propodus with two simple setae on dorsal margin.

Description: Female ( Fig. 62 ). 1.7 mm body length, body long, 7.3 times as long as wide. Carapace 1.5 times as long as wide, almost as long as pereonite-1 and 2 combined, 20% of total body length. All pereonites rectangular, with lateral margin parallel; pereonites 2 and 6 subequal, 1.5 times as long as pereonite-1; pereonite-3 slightly longer than pereonite-2, as long as wide; pereonites 4 and 5 subequal, as long as wide. Pleon a little longer than carapace; pleonites 1–5 subequal; pleotelson with well-developed distal process.

Antennule ( Fig. 63A ): Article-1 2.75 times as long as wide, 1.75 times as long as articles 2 and 3 combined, with two groups of simple and pinnate setae at middle and distally; article-2 with two short setae distally; article-3 twice as long as article-2, with two four setae distally.

Antenna ( Fig. 63B ): Article-2 slightly longer than article-3, with two setae almost as long as article-3; article-3 with one seta distally; article-4 1.75 times as long as article-5 with two simple and two pinnate setae distally; article 5 with one seta distally; article-6 small with four setae distally.

Mouth parts: Labrum, maxilla, maxilliped and epignath destroyed during dissection. Mandible ( Fig. 63C, D ) stout; molar process well-developed, with well-calcified distal margin supported with tubercle-like structures; lacinia mobilis well-developed, crenulated. Maxillule ( Fig. 63E ) endite with eight apical spiniform setae with numerous delicate short seta along margins; palp lost during dissection. Both lobes of labium ( Fig. 63F ) poorly separated, hirsute in distal parts.

Cheliped ( Fig. 64A ): Basis 1.9 times as long as wide; merus wedge-shaped, with one short seta ventrally; carpus over 2.3 times as long as broad, with two dorsal setae and with two short setae ventrally; propodus and fixed finger as long as carpus, over three times as long as wide; fixed finger with three teeth and three setae on inner margin and two setae on ventral margin.

Pereopod-1 ( Fig. 64B ): Slender (walking type); coxa present; basis a little shorter than merus, carpus and propodus combined, with two setae on dorsal margin and one seta on ventral margin; ischium with simple seta; merus almost as long as carpus, with two setae distally; carpus with two short, simple and one spiniform setae distally; propodus with three subdistal seta dorsally; dactylus 0.3 times length of propodus.

Pereopod-2 ( Fig. 64C ): Slender (walking type); basis as long as merus, carpus and half of propodus combined, with one seta ventrally and one seta dorsally; ischium with simple seta; merus almost as long as carpus with two setae distally; carpus with four short simple setae and one spiniform seta distally; propodus with one spiniform seta ventrally and two simple setae dorsally reaching end of dactylus.

Pereopod-3 ( Fig. 64D ): Similar to pereopod-2.

Pereopod-4 ( Fig. 64E ): Clinging type; basis three times as long as wide; ischium with two setae; merus with two spiniform setae; carpus with spiniform hooks and large prickly tubercles, as long as carpus; propodus almost four times as long as wide, with two spiniform ventro-distal setae and with distal seta just reaching half of dactylus; unguis simple, with dactylus almost as long as propodus.

Pereopods 5 and 6 lost during dissection.

Pleopods 1–5 ( Fig. 64F ): Basal article naked; exopod with eight plumose setae on outer margin and one seta on inner margin; endopod with twelve pinnate setae on outer margin. Gap between most proximal seta and other setae in both rami.

Uropod ( Fig. 64G ): Both rami two-articled. Endopod proximal article little longer than distal, with one pinnate seta distally; distal article tipped by five simple setae. Exopod two-articled; proximal article little longer than distal article, with two simple seta distally; distal article with two (short and long) terminal setae.

Distribution: North Atlantic Davis Strait, North of the Faroes, East and North of Iceland, south Jan Mayen at the depth range 906–2626m (temp. 0.6–1.5°C) and Iceland Plateau (69º24.8'N, 14º27.53'W) at depths of 1373–1629 m.

Figures

FIGURE 62. Typhlotanais mixtus Hansen, 1913, female. A), lateral view; B) dorsal view. Scale = 0.1 mm.

FIGURE 63. Typhlotanais mixtus, female. A) Antennule; B) Antenna; C) Left mandible; D) Right mandible incisor; E) Maxillule; F) Labium. Scale: A, B = 0.1 mm; C–F = 0.01 mm.

FIGURE 64. Typhlotanais mixtus, female. A) Cheliped; B) Pereopod-1; C) Pereopod-2; D) Pereopod-3; E) Pereopod-4; F) Pleopod; G) Uropod. Scale = 0.1 mm.