Metatanais bipunctatus, Blazewicz-Paszkowycz & Zemko, 2009

Blazewicz-Paszkowycz, Magdalena & Zemko, Karol, 2009, A new species of Metatanais Shiino, 1952 (Crustacea, Tanaidacea, Paratanaoidea) from Australian coral reefs, with a redefinition of the genus, ZooKeys 18 (18), pp. 129-141 : 133-139

Metatanais bipunctatus sp. n.

urn:lsid:zoobank.org:act:0DFA750C-CDC5-43FB-9083-CB8FD71AA9CA

Figs 3–5

Material examined: Holotype: Female (1.7 mm) ( MTQ W31164), CGLI 31 , 14.68039°S, 145.4453°E, Lizard Island , Casuarina Beach, dead coral, depth 1 m, 15

Apr 2008. Paratypes: 1 specimen (1.5 mm), ( MTQ W31164), CGLI 20, 14°64.553’S, 145°65.335’E, North Point, dead coral rubble, depth 0.5–1.5 m, 12 Apr 2008. 1 specimen, dissected in slides ( WAM C42469), NIN 17, Western Australia, Ningaloo Reef, off Tantabiddy, reef front 21.92833°S, 113.9196°E, dead Acropora head, depth 13–15 m, 17 Jun 2008.

Diagnosis: Body over four times as long as wide. Antennule article 1 less than twice as long as wide. Pereopod 4–6 propodus compact (about three times as long as wide), with spiniform setae ventrally.

Etymology: bipunctatus [Latin]: with two spots, referring to presence of dorsal orange spots, one on the posterior of the carapace and one on pereonite 6.

Description: Female without oostegites ( Fig. 1A, B ) 1.5 mm long. Body about 4.5 times as long as wide. Carapace 16% of body length, as long as wide, without rostrum, tapering towards the anterior, with mid-dorsal orange spot near posterior margin. Pereon about half of total body length. All pereonites wider than long, margins rounded in dorsal view. Pereonite 1 0.25 times as long as wide; pereonites 2 and 3 subequal and little longer than pereonite 1. Pereonites 4 and 5 subequal, 0.4 times as long as wide. Pereonite 6 subequal to pereonite 2, with orange spot mid-dorsally. Pleonites subequal in size (0.15 times as long as wide); pleotelson as long as combined length of pleonites 3 to 5, tapering posteriorly, produced medially.

Antennule ( Fig. 2A ) three-articled; article 1 barrel-shaped, half as long as carapace, less than twice as long as wide, with two simple, blunt setae on distal upper margin, distally overlapping base of article 2. Article 2 as long as wide, about one fifth as long as article 1, with one seta. Article 3 subequal in length to article 2, but slightly narrower, with one long and two short rod setae and one aesthetasc distally.

Antenna ( Fig. 2B ) six-articled. Article 2 1.1 times as long as wide, with one setae distally. Article 3 little shorter than wide, half as long as article 2, with one simple setae distally. Article 4 compact, about twice as long as wide, and subequal in length to article 2, with two pinnate setae along the dorsal margin. Article 5 1.3 times as long as wide, with one simple seta distally. Article 6 minute, with two long and two short distal setae.

Mouthparts: Labrum ( Fig. 2C ) hood shaped, with fine setae. Left mandible ( Fig. 2D ) molar robust, as long as wide, incisor with sharp processes distally; lacinia mobilis of moderate size, distal margin crenulated; right mandible ( Fig. 2E ) incisor process simple, lacinia mobilis absent. Maxillule ( Fig. 2G ) endite with eight spiniform setae distally and setose outer margin. Palp ( Fig. 2 G') with two articles, distal article tipped by two long simple setae. Maxilla ( Fig. 2H ) triangular, naked. Maxilliped ( Fig. 2F ) bases semi-fused; endites plate-like, exceeding bases of maxilliped distally and laterally, with one long simple setae distally and anterolateral rows of fine setae. Maxilliped palp article 1 with simple seta on outer margin; article 2 wedge-shaped with two plumose and one simple seta on the inner margin; article 3 with one plumose seta and three simple setae on the inner margin; article 4 with five plumose setae distally and one simple seta on outer margin.

Epignath ( Fig. 2I , I') narrow with six short simple setae on distal margin.

Cheliped ( Fig. 3A ) basis as long as wide; similar in size to sidepiece. Merus wedgeshape, naked. Carpus 1.3 times as long as wide, with one seta on dorsal margin. Propodus massive about twice as long as wide; palm little longer than dactylus; fixed finger

with strongly calcified inner margin; two small setae on ventral margin. Dactylus little longer than well-calcified unguis.

Pereopod 1 ( Fig. 3B ) coxa with one simple seta on dorsal margin; basis about as long as combined length of carpus and propodus, 5.3 times as long as wide. Ischium naked. Merus as long as carpus, naked. Carpus with two spines and one seta distally ( Fig. 3 B'). Propodus ( Fig. 3 '') 1.4 times as long as carpus, with two dorso-distal rod setae and one minute spine ventrally. Dactylus shorter than unguis.

Pereopod 2 ( Fig. 3 C–C'') similar to pereopod 1, but propodus ( Fig. 3 C'') with one rod seta dorso-distally.

Pereopod 3 ( Fig. 3D ) similar to pereopod 2, but merus with two minute distal spines ventrally, propodus without simple setae on the dorsal margin.

Pereopod 4 ( Fig. 3E ) basis broken; ischium with one simple seta, merus with two short spines disto-ventrally; carpus with one rod seta and spine distally, propodus with one simple seta distally, one spine ventrally and one fine seta in middle of dorsal margin; dactylus twice as long as unguis, curved.

Pereopod 5 ( Fig. 3F ) similar to pereopod 4, but ischium naked and carpus with three thick short distal spines.

Pereopod 6 ( Fig. 3G ) similar to pereopod 5, but propodus with four short simple setae distally.

Uropod ( Fig. 3H ) rudimentary; uniramous, basal article wider than long, embracing base of ramus article 1; article 2 rudimentary with one short and four long rod setae distally.

Distribution. Th e species was recorded from reefs around Lizard Island (northeastern Australia) and Ningaloo Reef, (north-western Australia) in coral rubble and on dead heads of coral at depths down to 15 m.

Figures

Figure 1. Metatanais cylindricus Shiino 1952 female, lectotype A body, dorsal B body, lateral. Scale bar equals 1 mm.

Figure 2. Metatanais cylindricus Shiino, 1952, female, lectotype.A antennule B antenna C chela D pereopod 1 E pereopod 2 F pereopod 3 G pereopod 4 H pereopod 5 I pereopod 6. Scale bars equal 0.1mm.

Figure 3. Metatanais bipunctatus sp. n. female, A body, dorsal B body, lateral. Scale bar equals 1 mm.

Figure 4. Metatanais bipunctatus sp. n. paratype, female. A antennule B antenna C labrum D left mandible E right mandible F maxilliped G maxillule G' maxillule palp H maxilla I epignath I' detail of epignath. Scale bars equals 0.01mm.

Figure 5. Metatanais bipunctatus sp. n. paratype female. A cheliped B pereopod 1 B' pereopod 1 carpus detail B''pereopod 1 propodus detail C pereopod 2 C' pereopod 2 carpus detail C''pereopod 2 propodus detail D pereopod 3 E pereopod 4 F pereopod 5 G pereopod 6 H uropod. Scale bars equal 0.1mm for A–G; 0.01 mm for H.