Typhlotanais spinicauda 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 : 117-120

Typhlotanais spinicauda Hansen, 1913

( Figs 68–70 )

Typhlotanais spinicauda: Hansen (1913) 3 (3): 53–54; Niestrasz (1913) 32: 37; Stephensen (1913) 22: 268–269, 418; Stephensen (1936) 6: 35; Lang (1970) (2), 23 (4): 277, 288; Morino (1971) 18(5): 353; Hassak & Holdich (1987) 16(3): 224, 226–229; Kudinova-Pasternak (1990 b) 69: 139; Larsen (2005): 210.

Material examined: Holotype: non-ovigerous female, Davis Strait , Ingolf St. 28, 65°14’N, 55°42’W; depth 420 fm (= 768 m) ; Other material: two females BIOICE 2257 (one dissected on slides), Irminger Basin, 5 Sep 1992, 63 o 14.61'N 26 o 29.14'W, depth 1209 m, epibenthic sled (Rothlisberg-Pearcy); bottom temp. 4.09ºC, salinity 34.94 o/oo, clay with shell sand.

Diagnosis: Pereopods 2 and 3 carpus with spiniform setae only; propodus with two regular dorso-distal seta (one more robust then the other).

Complementary description: Non-ovigerous female. Body length 2.3 mm ( Fig. 68A,B ), body long, 7.5 times as long as wide; carapace smooth, 1.4 times as long as wide, margins almost parallel, tapering proximally; rostrum weakly pointed; pereonites smooth, rectangular, with parallel lateral margins: pereonite-1 shortest, 2.2 times as wide as long; pereonites 2 and 6 0.7 times as long as wide; pereonite-3 square; pereonites 4 and 5 subequal, slightly shorter than wide. Pleon about as long as carapace and pereonite-1 combined; pleonites 1–5 similar in size; pleotelson rounded; caudal projection with two strong spines ( Fig. 68D ).

Antennule ( Fig. 69A ): Article-1 about twice as long as wide and twice as long as article-3, strongly taper- ing distally, with one simple seta and two pinnate setae distally and three short setae in row on outer margin; article-2 as long as wide with small simple and one pinnate setae distally; article-3 three times as long as article-2, with six distal setae.

Antenna ( Fig. 69B ): Articles 1 and 2 broken; article-2 with one simple seta distally; article-3 naked; article-4 twice as long as article-5, with four setae distally; article-5 with simple seta; article-6 with six simple subterminal and terminal setae.

Mouth parts: Labrum ( Fig. 69C ) hood-shaped, covered by numerous relatively long setae. Mandible (Figs

69D,E) stout; molar process well-developed, with strongly crenulated edges ( Figs 69 D’,E’); lacinia mobilis well-developed, crenulated. Maxillule ( Fig. 69F ) endite with eight terminal spiniform setae, three short simple setae on outer margin as well as on inner margin; palp lost during dissection. Maxilla elongated ( Fig. 69G ). Maxilliped ( Fig. 69I ) bases nearly twice as long as wide, without simple setae distally; each endite with two setae and two large tubercles on distal margin; palp article-1 naked; article-2 wedge-shaped, with three simple setae on inner margin and one short, simple seta on outer margin; article-3 trapezoidal; with four setae on inner margin; article-4 with one simple seta on outer margin and five strong terminal setae. Labium ( Fig. 69H ) with group of setae on outer corner of inner lobe; outer lobe with small setae.

Cheliped ( Fig. 70A ): Basis less than twice as long as wide, naked, not reaching pereonite-1 ventrally ( Fig. 68C ); merus with one seta; carpus twice as long as wide, covered by numerous scales, with two simple setae and one minute ventrally and one short setae dorsally; carpal shield poorly developed; chela almost as long as carpus, three times as long as wide and with three setae on inner margin, with two simple setae ventrally; dactylus curved distally, slightly longer than fixed finger, with one short seta proximally.

Pereopod-1 ( Fig. 70B ): Of walking type; coxa naked; basis just as long as propodus and carpus combined, with two setae dorsally and two setae ventrally; ischium short with one simple seta; merus almost as long as carpus, with one short seta dorso-distally; carpus with four short setae distally; propodus with two subdistal setae dorsally and minute subdistal seta ventrally; unguis 1.5 times as long as dactylus; unguis and dactylus somewhat shorter than propodus.

Pereopod-2 ( Fig. 70C ): Of walking type; basis just as long as merus, carpus and propodus combined, with three short seta along article; ischium with one seta; merus as long as carpus, with two simple and spiniform setae distally; carpus with two spiniform setae distally; propodus with spiniform seta ventrally and with two setae dorsally and one more robust than the other; dactylus shorter than unguis, combined shorter than propodus.

Pereopod-3 ( Fig. 70D ): Similar to pereopod-2, but basis as long as rest of articles combined.

Pereopod-4 ( Fig. 70E ): Of clinging type; basis with two pinnate setae ventrally; ischium with two setae; merus almost as long as carpus, with two subdistal spiniform setae; carpus with hooks distally and with large (over half as long as article) prickly tubercles ventrally; propodus twice as long as carpus, with two spiniform setae ventrally, one distal seta reaching over half of dactylus; dactylus tipped by simple unguis; dactylus and unguis as long as propodus.

Pereopod-5 ( Fig. 70F ): Similar to pereopod-4.

Pereopod-6 ( Fig. 70G ): Similar to pereopod-5, but propodus with three terminal setae and carpus with two dorso-distal setae.

Pleopods 1–5 ( Fig. 70H ): All pleopods similar; exopod with eleven plumose setae on outer margin and with one plumose seta one inner margin; endopod with twelve plumose setae on outer margin; both rami with clear gap between proximal outer seta and others.

Uropod ( Fig. 68D ): Basal article shorter than endopod proximal article; exopod and endopod two-articled; exopod articles subequal, combined shorter that endopod proximal article; distal article tipped by one long and one short seta; endopod proximal article with six spiniform setae on inner margin; endopod distal article with one subdistal and four distal setae.

Distribution: known from Arctic Davis Strait ( Hansen 1913) and Iceland-Rockall sector of North Atlantic (Bird personal comm.)

Remarks: T. spinicauda differs from T. squamiger n. sp. in having smaller spiniform setae on the merus, carpus and propodus of pereopods 2 and 3, and much smaller spiniform setae ventrally on the propodus of pereopods 4–6. These spiniform setae are especially robust in T. squamiger . Also, the scale-like cuticular structures covering the antennules, chelae and pereopods are more distinct in T. squamiger than in T. spinicauda . Those scale-like structures occur also on the cheliped bases and in specific light conditions can be visible as ‘teeth’ when seen laterally.

Figures

FIGURE 68. Typhlotanais spinicauda Hansen, 1913, holotype, female. A) dorsal view; B) Holotype, female, lateral view; C) Carapace, ventral view. D) Pleotelson with uropod. Scale: A, B = 1 mm; C, D = 0.1 mm.

FIGURE 69. Typhlotanais spinicauda, female paratype. A) Antennule; B) Antenna; C) Labrum; D) Left mandible; D’) Molar process; E) Right mandible; E’) Molar process; F) Maxillule; G) Maxilla; H) Labium; I) Maxilliped. Scale: A, B = 0.1 mm; C–I = 0.01 mm.

FIGURE 70. Typhlotanais spinicauda, female paratype. A) Cheliped; B) Pereopod-1; C) Pereopod-2; D) Pereopod-3; E) Pereopod-4; F) Pereopod-5; G) Pereopod-6; H) Pleopod. Scale = 0.1 mm.