Typhlotanais grahami, Blażewicz-Paszkowycz, Magdalena, 2004

Blażewicz-Paszkowycz, Magdalena, 2004, A description of a new species of Typhlotanais (Crustacea: Tanaidacea) from West Antarctic with a note on the genus, Zootaxa 535, pp. 1-12 : 2-9

Typhlotanais grahami n. sp. ( Fig. 1–3 )

Peraeospinosus sp.: Blażewicz & Jażdżewski, 1996 Polish Polar Research, 17, 213–220 Peraeospinosus sp. A: Blażewicz­Paszkowycz & Jażdżewski (2000) Polish Polar Research, 21(3– 4), 171–180

Peraeospinosus sp. A: Blażewicz­Paszkowycz & Sekulska­Nalewajko (2004) Polar Biol, 27, 222– 230

Diagnosis. Female body length up to 1 mm, carapace smooth, rounded laterally, as long as wide; rostrum rounded; pereonites smooth rounded laterally; pleonites 1 – 5 similar in size; pleotelson rounded; mandible molar process well developed, with undulated, smooth (no spines or teeth) crushing surface; maxillule palp with nine terminal spiniform setae (two are fused together); chela (propodus) similar size as carpus, twice as long as wide; pleopodal endopod proximal seta reduced; uropod exopodite and endopodite 1­articled, exopodite about 2/3 of endopodite, its longer distal with large basal part and bend in the ¼ of it’s length. uropod endopodite with five terminal simple seta. Male of swimming type; body length 0.78 mm; carapace a little shorter than length of pereonites 1–2; all pereonites and pleomeres subequal except pereonites 5–6 that are longer; Pleotelson with well­developed caudal processes.

Material examined: Holotype, non­ovigerous female ( NSNM 1024255), body length 1 mm, Admiralty Bay, Ezcurra Inlet, Herve Cove (King George Island, South Shetland Islands, Antarctic); sample no. D­42 collected on 20 December 1993 at the depth 6 m during SCUBA diving within XVII Polish Antarctic Expedition; Paratypes from the same locality ( NSNM 1024256; 668 specimens).

Additional material: Admiralty Bay (King George Island): OC­245, depth 15 m, 2 Jan 1980 Van Veen Grab (VVG): 8 ΨΨ; OC­297, depth 18 m, 7 Mar 1980, VVG: 14 ΨΨ; OC­299, depth 15 m, 7 Mar 1980, VVG: 88 ΨΨ; OC­304, depth 10 m, 7 Mar 1980, VVG: 389 ΨΨ, 61 ɗɗ, 17 mancae; OC­302, depth 17 m, 7 Mar 1980, VVG: 3 ΨΨ; OC­306, depth 30m, 8 Mar 1980, VVG: 1 Ψ; OC­370, depth 47 m, 12 Nov 1983, dredging: 2 ΨΨ; OC­371, depth 57 m, 12 Nov 1983, dredging: 1 Ψ; OC­431, depth 120 m, 8 Feb 1985, VVG: 1 Ψ; OC­457, depth 46 m, 17 Mar 1985, VVG: 2 ΨΨ; OC­544, depth 20 m, 5 Jan 1986, VVG, 46 ΨΨ; OC­545, depth 26 m, 5 Jan 1986, VVG: 9 ΨΨ; OC­467, depth 33 m, 20 Mar 1985, VVG: 7 ΨΨ; OC­526, depth 45 m, 6 Nov 1985, VVG: 3 ΨΨ; OC­439, depth 52 m, 16 Feb 1985, VVG: 5 ΨΨ; OC­440, depth 56m, 16 Feb 1985, VVG: 8 ΨΨ; OC­582, depth 80 m, 17 Jan 1988 (dredging): 1 Ψ; D­ 15/VIII, depth 6 m, 6 Mar 1993, VVG: 7 ΨΨ; D­ 16/VI, depth 6 m, 12 Mar 1993, VVG: 152 ΨΨ; D­36, depth 3 m, 17 Dec 1993 ( SCUBA): 10 ΨΨ; D­38, depth 9 m, 17 Dec 1993 ( SCUBA): 242 ΨΨ; D­39, depth 12 m, 17 Dec 1993 ( SCUBA): 173 ΨΨ; D­44, depth 10 m, 20 Dec 1993 ( SCUBA): 172 ΨΨ; D­ 50, depth 20 m, 30 Jan 1994 ( SCUBA): 162 ΨΨ; D­51, depth 6 m, 7 Jan 1994 ( SCUBA): 14 ΨΨ; D­52, depth 2 m, 8 Jan 1994 ( SCUBA): 7 ΨΨ; D­53, depth 3 m, 8 Jan 1994 ( SCUBA): 1 Ψ.

Description. Ovigerous female. Body length 1 mm ( Fig. 1 A, 1B), 4.5 times as long as wide; carapace smooth, rounded laterally, and as long as wide; rostrum rounded; pereonites smooth with rounded lateral margins: pereonite 1 and 6 short, pereonite 2 and 3 slightly longer, pereonite 4 and 5 the longest; pleonites 1 – 5 similar in size; pleotelson rounded; caudal projection reduced ( Fig. 1 E).

Antennule ( Fig. 1 F): 3­articled; article 1 massive, about 1.5 times longer than article 2 and 3 combined, with distal and medial setae; article 2 shorter than article 3, with two simple and one plumose setae; article 3 tipped by five simple terminal setae.

Antenna ( Fig. 1 G): 6­articled; article 1 short; article 2 slightly longer than article 3, with one simple seta; article 4 twice as long as article 5, armed with two short distal setae; 5 with one simple distal seta; article 6 with two simple subterminal setae and four terminal setae.

Mouthparts: Labrum ( Fig. 2 C) hood­shaped, covered by numerous minute setae. Mandible ( Fig. 2 A, 2B) massive; molar process well developed, with undulated, smooth edges; right mandible ( Fig. 2 B) incisor with sharp smooth margin; left mandible ( Fig. 2 A) incisor undulated; lacinia mobilis well developed undulated. Maxillule ( Fig. 2 D) inner endite equal to palp, armed with nine terminal spiniform setae (two are stuck together, see Figure 4 ); palp with two pinnate setae of different lengths. Maxilla ( Fig. 2 E) kidney­shaped, naked. Maxilliped ( Fig. 2 F): coxa reduced; bases elongated and fused; each with simple setae; endite armed with plumose seta and two flat setae on distal margin; palp 4­articled: article 1 naked, article 2 wedge­shaped with two bipinnate setae on inner margin, article 3 trapezoidal with three bipinnate and one simple setae on inner margin, article 4 slender (1.5 times as long as wide) with one simple seta on outer margin and five bipinnate terminal setae.

Cheliped ( Fig. 2 G): slender; basis with one simple seta on outer margin, posterior margin rounded; merus wedge­shaped with seta on ventral margin; carpus twice as long as wide (length wide ratio 2.1), with two setae ventrally; chela subequal to carpus, twice as long as wide, with one seta at insertion of dactylus; inner margin of fixed finger with two or three teeth and three setae in distal part, ventral margin with two simple setae; dactylus slightly curved, with two spiniform setae on inner margin.

Pereopod 1 ( Fig. 2 H) of walking type; basis naked, longer than ischium, merus and carpus combined; ischium short; carpus slightly longer than merus but shorter than propodus; ischium, merus and carpus each with one ventral seta; carpus also with dorsal seta, propodus with two serrate, subdistal setae; unguis 1.5 times as long as dactylus.

Pereopod 2 ( Fig. 2 I) of walking type; basis subequal to rest of articles combined; ischium short, with one seta on ventral margin; merus subequal to carpus, both with two distal setae (carpal setae one shorter than another); propodus longer than carpus, dorsal margin with two distal setae and two spiniform setae on ventral margin; dactylus shorter than unguis.

Pereopod 3 ( Fig. 2 J) similar to pereopod 2 but one distal carpal seta modified to short spiniform seta.

Pereopod 4 ( Fig. 2 K) of clinging type; basis wide slightly shorter than ischium, merus and carpus combined, with two pinnate setae distally; ischium with one seta; carpus subequal to merus with two subdistal setae on dorsal margin, and couples of specialised spines/cusps on merus and carpus; propodus twice as long as carpus ventral margin with one terminal serrate seta and two spiniform setae; dactylus tipped by minute unguis.

Pereopod 5 ( Fig. 2 L): similar to pereopod 4 except merus with two additional spiniform setae.

Pereopod 6 ( Fig. 2 M): similar to pereopod 5 but basis naked, ischium with two simple setae, propodus with three terminal setae.

Pleopod 1–5 ( Fig. 1 H): all pleopods similar; basal article with one circumplumose seta, endopod outer margin with six plumose setae, inner margin with one plumose seta; exopod armed with twelve plumose setae on outer margin; proximal seta reduced.

Uropod ( Fig. 1 D, 1E): uropod exopodite and endopodite 1­articled, exopodite about 2/ 3 of endopodite, its longer distal with large basal part and bend in the ¼ of it’s length; uropod endopodite with five terminal simple setae.

Male ( Fig. 1 C): of swimming type; body length 0.78 mm cephalothorax a little shorter than the length of three first pereonites. All pereonites and pleonites subequal except pereonite 5 and 6, which are longer than others. Pleotelson with well­developed caudal processes ( Fig. 3 L).

Antennule ( Fig. 3 A): 7­articled; article 1 and 2 subequal and massive with some simple medial setae; article 3 twice as long as article 4 and with two distal setae, article 5 as

long as article 6 and 7 combined, article 6 little longer than 7; articles 4–7 with aesthetascs.

Antenna ( Fig. 3 B): 7­articled, articles 1–4 subequal, article 3 with one distal seta; article 5–6 subequal, article 7 half as article 6 length; articles 5–7 with simple subdistal or distal setae.

Maxilliped ( Fig. 3 C): bases fused; endite lobe­shaped; palp 4­articled: article 1 unarmed, article 2 with distal setae, articles 3 and 4 armed in with four distal setae.

Cheliped ( Fig. 3 D): slender; basis unarmed and rounded distally, merus wedge­shaped with simple seta on ventral margin; carpus more massive than that of female (length: wide ratio 1.7), trapezoidal, with two setae on ventral margin; chela more slender than carpus, fixed finger tipped by large spinose seta, three setae on dorsal margin, one on ventral margin; propodus inner side with row of nine setae distally (eight short and one long); dactylus slightly curved with two spiniform setae on inner margin.

Pereopod 1 ( Fig. 3 E): of walking type; basis slightly shorter than ischium, merus, carpus combined; ischium short, with one seta; merus and carpus subequal; propodus slightly longer than carpus; dactylus as long as half propodus with long unguis (longer than dactylus).

Pereopod 2 ( Fig. 3 F): similar to pereopod 1, but a little shorter, ischium, merus, carpus and propodus with one simple seta on distal edge, propodus with one seta on dorsal margin additionally.

Pereopod 3 ( Fig. 3 G): similar to pereopod 2.

Pereopod 4 ( Fig. 3 H): of walking type; length proportions of articles are similar to pereopod 1; ischium with one seta, merus and propodus distal parts with two/three distal spiniform setae; carpus dorsal margin one aesthetascs (rod­like seta) propodus dorsal margin with one terminal seta; dactylus subequal to unguis.

Pereopod 5 ( Fig. 3 I): similar to pereopod 4 but basis more massive and armed with plumose submedial setae.

Pereopod 6 ( Fig. 3 J): similar to pereopod 4 but ischium with two setae and propodus armed with three terminal spiniform setae.

Pleopods 1–5 ( Fig. 3 K): all pleopods of similar size and structure; endopod with five long plumose setae on outer margin and single seta on inner margin; exopod with nine plumose setae on outer margin.

Uropod ( Fig. 3 L, 3M) exopod 1­articled, as long as endopod article 1, with two terminal setae and simple short seta in the middle of article; exopod 2­articled; articles subequal; article 2 with five terminal simple setae.

Distribution. Species known only from the type locality: Admiralty Bay, King George Island, South Shetland Islands, the Antarctic; depth range 2– 120 m.

Etymology. This species is named in honour of Dr Graham Bird (Sunfish Consultants Ldt., U.K.) in recognition of his extensive experience in Tanaidacea .

Remarks. The female of the new species is characterized by (1) a smooth carapace, as long as it is wide; (2) pereonites smoothly rounded laterally; (3) a rounded pleotelson; (4) an undulated, smooth mandible molar process; (5) nine terminal spiniform setae (two are fused together) on the maxillule palp; (6) a chela (propodus) of similar size to the carpus, and twice as long as it is wide; (7) a reduced proximal seta on the pleopodal endopod; (8) a uropod exopodite with one article, about 2/3 of the endopodal length, which is longer distally with a large basal part and a bend about a quarter of the way along its length.

Genus Typhlotanais is represented in Antarctic waters by eight species: T. dubius Tzareva, 1982 , T. gruzovi Tzareva, 1982 , T. greenwichensis Shiino, 1970 , T. longus Kudinova­ Pasternak, 1975, T. parangularis Kudinova­Pasternak, 1975 , T. parvus Sieg, 1986 , T. plicatus Kudinova­Pasternak, 1993 , and T. grahami n. sp. The most distinct of these Typhlotanais species is T. plicatus with its unique transverse rings on pereonites 1–3. Typhlotanais parangularis is characterized by trapezoidal­shape pereonites 1–3, by a bifurcated unguis on pereopods 4–6, and chelipeds which are attached anteriorly, i.e. the edge of the cheliped basis does not reach the first pereonite. Typhlotanais longus is distinguished by a long pereonite 1 (subequal to carapace) and a trifurcated unguis on pereopod 6, while T. greenwichensis displays projections on the basis of pereopods 1–3 and a row of minute setae on the dorsal margin of the carpal cheliped; T. dubius has a thick spiniform seta near the cheliped unguis and an acute mandibular molar process, while T. gruzovi has pereopod 4 and 5 adapted for walking. The acute molar part of the mandible and the lack of clinging pereopods 4–6 should separate both the species ( T. dubious and T. gruzovi ) of genus Typhlotanais . However, because the type material is not available for re­examination, their taxonomical status must be accepted at the present stage. Typhlotanais grahami is superficially most similar to T. parvus but laterally rounded carapace and characteristic setation of exopod uropod immediately distinguish T. grahami from T. parvus .

Figures

FIGURE 1. Typhlotanais grahami n. sp., A – B, female paratype lateral and dorsal view; C, male dorsal view; D, female uropod; E, female pleotelson and uropods; F, female antennule; G, female antenna; H, female pleopod. Scale bar: a = 0.1 mm for A – C; a = 0.2 mm for E, a = 0.05 mm for D, b = 0.1 mm for F – G, c = 0.1 mm for H.

FIGURE 2. Typhlotanais grahami n. sp, female: A, left mandible; B, right mandible; C, labrum; D, maxillule; E, maxilla; F, maxilliped; G, cheliped; H—M, pereopods 1 — 6; Scale bar: 0.05 mm for D; 0.2 mm for G; 0.1 mm for A—C, E—F, H—M.

FIGURE 3. Typhlotanais grahami n. sp. male: A, antennule; B, antenna; C, maxilliped; D, cheliped; E – J, pereopods 1 – 6; K, pleopod; L, pleotelson; M, uropod. Scale bar: a = 0.1 mm for D, L; b = 0.1 mm for A – C, E – K, M.

FIGURE 4. Typhlotanais grahami n. sp, female: tip of maxillule with two fused spiniform setae.