Paratyphlotanais alveolus, 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 : 20-24

Paratyphlotanais alveolus n. sp.

( Figs 8–10 )

Material examined: Holotype: one female, ( K 41390 ), ANT XXII-3 , PS 67/74-6-E, 71°18.35’– 71°18.28’S, 13°57.71’– 13°57.31’W, depth 1030–1040 m, 20 Feb 2005 ; Paratypes: two females (one dissected on slides), ( K 41387 ), ANT XXII-3 , PS67/133-2-S, 62°46.49’– 62°46.38’S, 53°3.50’– 53°3.98’W, depth 1584– 1579 m, 16 Mar 2005 ; eight females, ( K 41389 ), ANT XXII-3 , PS 67/133-2-Epi, the same locality ; one female, (K 41 391), ANT XXII-3 , PS 67/80-9-Epi, 70°39.07’– 70°39.22’S, 14°43.36’– 14° 43.39’W, depth 3102– 3102 m, 23 Feb 2005 ; one female, ( K 41449 ), ANT XXII-3 , PS 67/80-9-S, the same locality; three mancae, ( K 41388 ), ANT XXII-3 , PS 67/74-6-S, 71°18.35’– 71°18.28’S, 13°57.71’– 13°57.31’W, depth 1030–1040 m, 20 Feb 2005 .

Diagnosis (neuter/female): Paratyphlotanais with complex pereon outline; pereonite-1 depressed dorsally, with large hyposphaenium; pereonites 2 and 3 with hyposphaenium prominent; pereonites 4 and 5 with small hyposphaenium. Pereopods 1–2 coxa with large spur. Chelipeds gracile with one ventral carpal seta exceeding carpal width and with only two setae dorsally; meral and carpal spiniform setae of pereopods 1–3 only weakly serrate. Uropod endopod up to ten times as long as broad.

Etymology: Alveolus [Lat.] = cavity, tray, river-bed. The name alludes to the dorso-ventrally depressed form of pereonite-1.

Description: Non-ovigerous female body length 2.8 mm ( Fig. 8A,B ). Cephalothorax 15% of total length, 1.5 times as long as basal width; rostrum pointed, overlapping base of antennules. Pereonites 1–3 narrower caudally; pereonites 4 and 5 rounded; pereonite-6 narrowest rostrally; pereonite-1 four times wider than long, depressed at middle; pereonites width: length ratios: 3.5, 1.5, 1.2, 1.2, 1.0, 1.4 respectively; large sternal hyposphaenium on pereonite-1, prominent hook on each of pereonites 2 and 3, and small hook on each of pereonites 4 and 5. Pleon 22% of body length, little longer than carapace. Pleotelson ( Fig. 10H ) rectangular, just longer than two preceding pleonites, with modest apex.

Antennule ( Fig. 9A ): Almost 0.6 times length of cephalothorax; article-1 twice as long as wide, 1.4 times as long as articles 2 and 3 combined, with four setae along margin and one long (longer than article-2) simple seta and two pinnate setae distally; article-2 half as long as article-3, with one long (just as article-3) distal seta; article-3 with terminal spur and four simple setae distally.

Antenna ( Fig. 9B ): Article-2 three times as long as article-3, with dorsal seta; article-3 naked; article-4 with two long, one short and one pinnate setae distally, 4.5 times as long as wide; article-5 with one terminal seta; article-6 with four setae.

Mouth parts: Labrum ( Fig. 9C ) with rounded, setose distal margin. Mandible ( Fig. 9D,E ) molar broad with crenulated margin, and crenulated incisor; left mandible with broad lacinia mobilis. Maxillule endite ( Fig. 9F ) with eight distal setae; palp ( Fig. 9 F’) with two terminal setae. Maxilla ( Fig. 9G ) oval. Labium ( Fig. 9H ) with inner lobe setose distally and with minute setae along margin on outer lobe. Maxilliped ( Fig. 9I ) basis 1.5 times as long as wide, with long seta reaching over endites distally; endites with one tubercle and one seta on distal margin; palp four-articled: article-1 naked; article-2 wedge-shaped, with three setae on inner margin and one relatively long seta on outer margin; article-3 with three long and one short setae on inner margin; article-4 shorter than article-3 with four long and two short setae distally.

Cheliped ( Fig. 10A ): Basis over twice as long as wide; merus triangular with long ventral seta; carpus three times as long as broad, with two small setae dorsally and two subequal, long setae and one minute seta ventrally; propodus and fixed finger slender, about three times as long as broad; dactylus about 0.7 times as long as propodus, with one seta near insertion of dactylus; fixed finger with three setae on strongly calcified inner margin and two setae on ventral margin; dactylus little shorter than fixed finger, with small setae in proximal part of dorsal margin.

Pereopod-1 ( Fig. 10B ): Coxa with one seta on spur; basis slender 6.5 times as long as broad, a little longer than merus and carpus combined, with proximal seta ventrally; ischium with small seta; merus about twice as long as broad, with spiniform ventral seta and simple dorsal seta; carpus little longer than merus, 2.3 times as long as broad, with spiniform dorsal seta and four minute setae distally; propodus about five times as long as broad, with one short serrate and one simple seta distally; dactylus and unguis about as long as propodus, unguis longer than dactylus.

Pereopod-2 ( Fig. 10C ): Coxa with one seta; basis slender, about six times as long as broad, with proximal and distal seta dorsally; ischium with small seta; merus about twice as long as broad, with ventral spine and two setae distally; carpus as long as merus, with two spiniform and five minute setae distally; propodus about 1.5 times as long as carpus, with one disto-dorsal spiniform seta and one minute seta ventrally; dactylus and unguis together as long as propodus.

Pereopod-3 ( Fig. 10D ): Similar to pereopod-2, but coxa without prominent spur, basis with one seta ventrally.

Pereopod-4 ( Fig. 10E ): More robust than pereopods 1–3; basis three times as long as wide, as long as merus, carpus and propodus combined, naked; ischium with one seta; merus, with two spiniform ventral serrate setae; carpus almost as long as merus, three times as long as broad, with four spiniform setae (one longer than the others); propodus little longer than carpus, with two spiniform setae on ventral margin and one spiniform seta distally; unguis 0.3 times dactylus length, combined 0.6 times propodus length.

Pereopod-5: similar to pereopod-4.

Pereopod-6 ( Fig. 10F ): Basis about three times as long as wide and almost as long as merus, carpus and propodus combined, with one pinnate seta ventrally; ischium with one seta; merus with two spiniform serrated setae ventrally; carpus almost as long as merus, twice as long as broad, with four spiniform setae and two short simple setae distally; propodus longer than carpus, with one spiniform seta subdistally on ventral margin and three spiniform setae distally reaching half of dactylus; unguis and dactylus 0.3 times as long as of propodus; unguis 0.3 times as long as dactylus.

Pleopods ( Fig. 10G ): Both rami subovate, with proximal seta separated from the others; endopod with ten plumose setae, exopod with twenty plumose setae.

Uropods ( Fig. 10H ): Very slender, nearly twice as long as pleotelson; endopod two-articled, proximal article 0.7 times length of ramus, ten times as long as broad; exopod one-articled almost as long as proximal article of endopod; setation as figured.

Distribution: Antarctic: Eastern Weddell Sea and line between tip of Antarctic Peninsula and Southern Orkney Island, at depths of 1030–3102 m.

Remarks: Paratyphlotanais alveolus n. sp. has a transverse depression on first pereonites. This unique character allows immediate recognition of the species; equally it is the only species with a coxal spur present only on the first pereopod.

Figures

FIGURE 8. Paratyphlotanais alveolus n. sp., holotype, adult female. A) dorsal view; B) lateral view. Scale = 0.1 mm.

FIGURE 9. Paratyphlotanais alveolus n. sp., female paratype. A) Antennule; B) Antenna; C) Labrum; D) Left mandible; E) Right mandible; F) Maxillule; F’) Palp; G) Maxilla; H) Labium; I) Maxilliped. Scale = A, B, I = 0.1 mm; C-H = 0.01 mm.

FIGURE 10. Paratyphlotanais alveolus n. sp., female paratype. A) Cheliped; B) Pereopod-1; C) Pereopod-2; D) Pereopod-3; E) Pereopod-4; F) Pereopod-6; G) Pleopod; H) Uropod. Scale = 0.1 mm