Pooreotanais ningaloo, Błażewicz-P, 2009

Błażewicz-P, Magdalena, 2009, A new genus of a new Austral family of paratanaoid tanaidacean (Crustacea: Peracarida: Tanaidacea), with two new species., Memoirs of Museum Victoria 66, pp. 5-15 : 11-14

Pooreotanais ningaloo sp. nov.

Figs 4–5

Material. Holotype female (Reg WAM 42784 ), NIN 14C, Ningaloo Reef front, south of Tintabiddy , Western Australia, 21° 54.505'S 113° 57.963'E, small and medium rubble in gully, 10 m depth, 15 June 2008 . Paratype: 1 female dissected on slides, 2.1 mm long, (Reg WAM 42785 ), NIN 5C, Ningaloo Reef , Western Australia, 21° 52.942'S 113° 58.367'E, dead head of coral, 4–5 m depth, 7 June 2008 .

Description of female. Body (fig. 4A) glabrous, generally cylindrical, with cephalothorax and pereonites 1 to 6 slender, pereonite 6 expanded, and pleon (“abdomen”) grossly inflated; holotype 2.27 mm long, pleon 1.7 mm long (0.75 times the length of the whole body). Cephalothorax subrectangular, wider than long, with slight rostrum, eyelobes and eyes absent. Six free pereonites; pereonite 1 shortest, 0.24 times as long as cephalothorax; pereonites 2, 3, 4 and 5 subequal in length, 2.75 times as long as pereonite 1, pereonite 6 expanded, twice as long as pereonite 5. Pleon of five free subequal pleonites plus pleotelson, all expanded; pleonites progressively longer, pleonite 1 about 1.5 times as long as pereonite 6 to pleonite 5 twice as long as pereonite 6; pleotelson stout, rounded, 1.3 times as long as last pleonite.

Antennule (fig. 4B) of four articles; proximal article stout, 1.7 times as long as wide, just shorter than distal three articles together, with one simple outer distal seta; article 2 just longer than wide, 0.5 times as long as article 1, with single distal inner and outer setae; article 3 half length of article 2 with single distal inner and outer setae; article 4 comparatively slender, three times as long as wide and 0.7 times as long as article 2, with six distal setae and one aesthetasc.

Antenna (fig. 4C) of six articles, proximal article compact, naked; article 2 as long as wide, with dorsodistal seta; article 3 wider than long, 0.75 times as long as article 2, with dorsodistal seta; article 4 longest, twice as long as article 2, twice as long as wide, with distinct indication of pseudoarticulation at mid-length, coincident with one penicillate seta, distally with three penicillate and three simple setae; article 5 half as long as article 4 with one long distal seta; article 6 comparatively minute, one-quarter length of article 5, with one subdistal and three distal strong setae.

Labrum (fig. 4D) rounded, naked. Left mandible (fig. 4F) with eight triangular teeth distally on pars incisiva; lacinia mobilis a slight, fused tooth; pars molaris not seen; right mandible (fig. 4E) with five distal triangular teeth, without lacinia mobilis. Labium (not figured) naked, without palp. Maxillule (fig. 4G) endite with five distal spines; palp distinct, unsegmented, with two distal setae. Maxilla (fig. 4G) small, ovoid, naked. Maxilliped (fig. 4H) palp article 1 naked; article 2 subrectangular, no outer setae, one simple inner seta; article 3 almost as wide as long, with one stout inner simple seta; article 4 with one shorter and four longer simple distal setae; basis naked; endites large, naked. Epignath not seen.

Cheliped (fig. 5A) robust, with rounded, elongate basis just less than twice as long as wide; merus subtriangular with one ventral seta; carpus just longer than wide, with mid-dorsal seta and dorsodistal seta, and two ventral setae; propodus longer than wide, with one ventral seta, cutting-edge of fixed finger almost perpendicular to axis of propodus, fixed finger with three distal outer setae, cutting edge minutely crenulated distally, inner setal row at base of dactylus of one seta; dactylus naked.

Pereopod 1 (fig. 5B) coxa naked; basis slender, 3.8 times as long as wide, naked; ischium compact, naked; merus shorter than carpus, both naked; propodus longer than carpus and merus together, with single ventral subdistal seta and three dorsodistal setae; dactylus slender, naked, extending into subequal curved unguis, the two together some 0.6 times as long as propodus. Pereopod 2 (fig. 5C) similar to pereopod 1, but coxa with a seta, carpus with one dorsodistal seta, propodus dorsally with one subdistal seta. Pereopod 3 (fig. 5D) similar to pereopod 2, but dactylus with one long proximal seta.

Pereopods 4 and 6 missing.

Pereopod 5 (fig. 5F) basis stouter than on anterior pereopods, 2.8 times as long as wide, naked; merus and carpus subequal, merus with two minutely denticulate, subdistally bifurcate slender ventrodistal spines; carpus with fine outer distal seta and two minutely denticulate, subdistally bifurcate curved ventrodistal spines; propodus with one minutely denticulate ventrodistal spines; dactylus and unguis not fused, unguis less than half as long as dactylus, distally bifurcate.

Pleopods absent.

Uropod (fig. 5E) compact, biramous, basis as wide as long, naked; exopod of one segment, half as long as proximal endopod segment, with one shorter and one longer distal setae; endopod of two segments, proximal segment wide than long, naked, distal segment 0.6 times as long as proximal segment, with four distal setae.

Male: unknown.

Etymology. Named after Ningaloo Reef , the type-locality (noun in apposition).

Remarks. Pooreotanais ningaloo sp. nov. shows the same features of the coarsely denticulate mandibular incisor and other mouthpart morphology, leg setation and proportionate length of expanded pleon as P. gari , and as listed in the diagnosis of the genus, to which it is accordingly attributed, and by which it is comfortably distinguished from Mirandotanais vorax .

The present species is equally distinct from P. gari on a number of features: the pereonites 4 and 5 are not expanded, but the inflated pleon contributes three-quarters of the bodylength (two-thirds in P. gari ); the pleotelson is longer than any pleonites (shorter in P. gari ); the articles of the antennule and antenna are more compact, and the pseudoarticulation of the antennal article 4 is not found in P. gari ; there are fewer distal spines on the maxillule endite, fewer teeth on the mandibular incisor, fewer inner setae on the maxilliped palp article 1, conversely one inner seta on the article 2 (none in P. gari ); there are also subtle differences in the (sparse) setation of the cheliped and pereopods.