Typhlotanais compactus Kudinova-Pasternak, 1966

Błażewicz-Paszkowycz, Magdalena, 2007, Family Nototanaidae Sieg, 1976 and Typhlotanaidae Sieg, 1984, Zootaxa 1599, pp. 101-120 : 108-113

Typhlotanais compactus Kudinova-Pasternak, 1966

Figures 4–6

Material examined. 5 females, station XR-12, 41º37.67’– 41º37.08’N 146º54.19’– 146º52.72’E, 5473– 5484 metres, 4 m ORE beam trawl, 26 September 2001. 2 females, station TD-4, 39°27.08’– 39°29.15’N 143°37.79’– 143°38.52’E, 3272–3146 metres, 26 September 2001.

Diagnosis. Body six to seven times as long as wide. Pereonites lateral edges rounded in dorsal view, all wider than long. Antennule longer than carapace; article 3 three times as long as article 2. Antenna article 4 seven times as long as wide. Cheliped carpus 2.5 times as long as wide; with two minute setae dorsally. Pereopods 1–3 with moderate size spur; pereopods 2–3 carpus and propodus with spiniform setae disto-ventrally; pereopods 2 and 3 merus without spiniform seta; pereopods 4–6 with prickly tubercles surrounded by row of spines; pereopods 4 and 5 with distal seta shorter than dactylus. Uropod endopod with two articles, proximal article as long exopod, with ten setae in distal half.

Complementary description of female

Body ( Figs 4 A,B). 3.1 mm, 6.6 times as long as wide.

Carapace. As long as wide, little shorter than pereonites 1 and 2 combined; lateral margins slightly rounded; rostrum slightly pointed.

Pereonites. Smooth, all wider than long. Pereonite 1 shortest, over twice as wide as long, half as long as pereonite 3. Pereonite 2 little shorter than pereonite 3 and subequal to pereonite 6. Pereonites 2, 4 and 5 subequal.

Pleon 1.3 times as long as carapace. Pleonites similar in size.

Pleotelson. Rounded.

Antennule ( Fig. 5 A). Article 1 short, 2.5 times as long as wide, with one simple and two pinnate setae at middle of outer margin, one long and one pinnate seta distally, and with row of four short setae on inner margin. Article 2 with one long and two short setae distally. Article 3 almost four times as long as article 2, with apical spur and five setae distally.

Antenna ( Fig. 5 B). Article 2 about as long as wide, article 2 and 3 with strong microtrichias. Article 4 seven times as long as wide, with two long and three pinnate setae distally. Article 5 with one simple seta distally. Article 6 very short, with six terminal setae.

Mouthparts. Labrum lost during dissection. Mandibles ( Figs 5 C,D) molar well developed, longer than incisor with irregular edges; incisor blunt; lacinia mobilis well developed, serrated. Maxillule ( Fig. 5 E) endite with eight apical spiniform setae, palp ( Fig. 5 E’) with two terminal setae. Labium both lobes ( Fig. 5 G) poorly setose distally. Maxilliped ( Fig. 5 I) basis 1.5 times as long as wide, with seta little shorter than endites; endite with two simple setae and two tubercles distally; palp article 1 unarmed; article 2 wedge-shaped, with three setae on inner margin and one seta on outer margin; article 3 trapezoidal, with four weakly serrated setae on inner margin; article 4 slender, with one simple seta on outer margin and five setae distally. Epignath ( Fig. 5 H) curved, simple distally.

Cheliped ( Fig. 6 A). Basis slightly rounded, almost twice as long as wide. Merus wedge shaped, with one seta ventrally. Carpus with two simple and one short setae ventrally, and two minute setae dorsally; propodus as long as carpus, with seta on inner and outer side near cheliped insertion. Fixed finger (propodus projection) tipped by strong spine, with three setae on well calcified inner margin and two setae ventrally. Dactylus slightly curved, with one short seta proximally on dorsal margin.

Pereopod 1 ( Fig. 6 B). Slender (walking type). Coxa with small spur. Basis five times as long as wide, subequal to carpus and propodus combined, with three setae dorsally and one seta ventrally. Ischium short, with one seta. Merus subequal to carpus, with two simple setae distally. Carpus with five setae distally. Propodus 1.4 times as long as carpus, with three setae sub-distally on dorsal margin. Dactylus half as long as unguis with one seta; both 0.8 times as long as propodus.

Pereopod 2 ( Fig. 6 C). Slender (walking type). Coxa with small spur. Basis 3.5 times as long as wide, with three setae dorsally and two ventrally. Ischium with simple seta. Merus as long as carpus, with one robust and three simple setae distally. Carpus with four simple setae and one spiniform distally; both merus and carpus with calcified microtrichiae ventrally. Propodus 1.7 as long as carpus, with spiniform seta ventrally and two setae dorsally. Dactylus half as long as unguis, with one simple seta.

Pereopod 3 ( Fig. 6 D). Similar to pereopod 2, but merus with two robust setae.

Pereopod 4 ( Fig. 6 E). Clinging type. Basis robust, twice as long as wide, with two pinnate setae ventrally and two minute dorsally. Ischium with two setae. Merus with one short and one spiniform seta ventrally. Carpus with spine distally and with prickly tubercles surrounded by row of minute spines, one seta disto-dorsally. Propodus with two spiniform setae ventrally and with one dorso-distal seta, about as long as half of dactylus. Dactylus half as long as propodus and four times as long as unguis; unguis bifurcated distally.

Pereopod 5 ( Fig. 6 F). Similar to pereopod 4.

Pereopod 6 ( Fig. 6 G). Similar to pereopod 5, but propodus with three dorso-distal setae.

Pleopod ( Fig. 6 H). Basal article naked. Exopod with one seta on inner margin and thirteen plumose setae on outer margin. Endopod with twenty one plumose setae on outer margin; clear gap between proximal seta and other setae in both rami.

Uropod ( Fig. 6 I). Basal article 1.7 as long as wide. Exopod 2-articled, as long as endopod proximal article, proximal article with minute setae distally, proximal article with one strong seta and one regular seta distally. Endopod 2-articled, proximal article three times as long as distal article, with five setae on outer and five setae on inner margin; distal article with four setae distally.

Remarks: Typhlotanais compactus Kudinova-Pasternak, 1966 can be distinguished from other described typhlotanaids by the unusual proximal article of the uropod endopod: this is almost three times as long as the distal article and also bears five simple setae on the outer and inner margin.

T. compactus displays a set of characters which inhibit its classification to any of the presently distinguished typhlotanaid genera. It lacks long seta in the propodus of pereopods 4 and 5 as in Peraeospinosus ; has short pereonite 1 unlike in Pulcherella ; has normally developed pereonite 1 in contrast to Torquella ; and has much shorter antennule than Typhlamia . T. compactus also cannot be classified in any of the morpho-groups distinguished by BłaŻewicz-Paszkowycz (2007). It lacks two spines on the pleotelson as have members of the ‘ spinicauda ’ group, lacks large prickly tubercles as members of the ‘ mixtus ’ group, and lacks corrugation on pereonites 1–3 as present in the members of the ‘ plicatus group ’. The new species has a short seta on the propodus of pereopod 4–6, distinguishing it from members of the ‘ cornutus ’ group and its body is much longer (over six times as long as wide) than in the ‘ eximus ’ and ‘ penicillatus ’ groups. Finally, because the new species has prickly tubercles surrounded by row of spines it certainly does not belong to Typhlotanais sensu stricto. Consequently, it is proposed to retain it at Typhlotanais sensu lato until a reasonable classification of Typhlotanais can be established.

Distribution: Typhlotanais compactus has been found at three localities by Kudinova-Pasternak in the North Pacific: 40°19.7'N, 175°45.3'E at the depth 6065 metres ( Kudinova-Pasternak 1966), 44°06.7'N, 155°54'E at the depth range from 4895–6135 metres ( Kudinova-Pasternak 1970), and 53°25.7'N, 163°28'E at the depth 4260 metres ( Kudinova-Pasternak 1973) ( Fig. 10 ).

Genus Larsenotanais BłaŻewicz-Paszkowycz, 2007

Diagnosis (after Błażewicz-Paszkowycz, 2007). Body long, more than five times as long as wide, all pereonites rounded laterally in dorsal view, wider than long, pereonite 1 shortest. Antennule less than twice as long as carapace; article 1 with at least five setae along article. Mandible molar with regular tubercles and teeth distally. Maxilliped basis with seta longer than endites; endites with two tubercles and two setae distally. Cheliped basis reaches the edge of pereonite 1. Pereopods 1–3 basis without acute projection; pereopod 1 merus without spiniform seta; pereopods 2 and 3 carpus and propodus with spiniform seta; pereopods 4–6 carpus with moderate prickly tubercles (less than half of carpus length), unguis simple, propodus distal setae shorter than dactylus. Both rami of pleopods with proximal seta separated from others by gap. Uropod rami 1-articled.

Species included: Larsenotanais amabilis BłaŻewicz-Paszkowycz, 2007 ; L. kamchatikus n.sp.

Figures

FIGURE 4. Typhlotanais compactus, adult female, A, lateral view; B, dorsal view. Scale = 1 mm.

FIGURE 5. Typhlotanais compactus, female A, Antennule; B, Antenna; C, Right mandible; D, Left mandible; E, Maxillule; E’, Maxillule palp; F, Maxilla G, Labium; H, epignath; I, Maxilliped. Scale = 0.1 mm.

FIGURE 6. Typhlotanais compactus, female A, Cheliped; B, Pereopod 1; C, Pereopod 2; D, Pereopod 3; E, Pereopod 4; F, Pereopod 5; G, Pereopod 6; H, Pleopod; I, Uropod. Scale = 0.1 mm.

FIGURE 10. Distribution of abyssal nototanaids and typhlotanaids from Kurile-Kamchatka region based on literature data (Hansen, 1913, Kudinova-Pasternak 1966, 1970, 1973, 1976, 1978) and present study.