Zeuxoides lauriebourqueae, Edgar, 2008

Edgar, Graham J., 2008, Shallow water Tanaidae (Crustacea: Tanaidacea) of Australia, Zootaxa 1836 (1), pp. 1-92 : 35-40

Zeuxoides lauriebourqueae n. sp.

( Figs 16–18 )

Material examined. Holotype. Ovigerous female ( NMV J56141 ), 5.3 mm, Canal Rocks, WA, 6 m, macroalgal washings, 19 Dec 1993.

Paratype. Male ( NMV J56142 ), 3.9 mm, holotype location .

Other material. One male, four females ( NMV J57283 ), Wreck Rock, Marmion Lagoon, WA, 5 m, sponge washings, 12 Jan 1993 . Three females ( NMV J57284 ), Marmion Lagoon, WA, 4-8 m, algal washings, 14 Jan 1993 .

Diagnosis. With characters of genus. Antennule article 1 about 2.5 (female) and 4.0 (male) times longer than wide, terminal article with five (female) and six to eight (male) aesthetascs; left mandible with lacinia mobilis reduced to acutely-pointed peg-like process, right mandible with lacinia mobilis reduced and thornlike; pereopod 1 coxa with pronounced anterior bulge with five setae; pleopod basal article with nine setae on outer margin, one seta on inner margin, endopod with six setae on inner margin; uropod with seven articles in mature individuals.

Description. FEMALE

Body ( Fig. 16 ). Length to 5.3 mm; preserved specimens with mottled pigmentation extending prominently from cephalothorax to pleonite 5 other than pereonites 1 and 2, and on chelipeds, antennules and antennae.

Cephalothorax rounded and narrowing anteriorly in dorsal view, slightly longer than wide, length just less than one quarter body length.

Pereon occupies about 56% of total length; pereonites with several setae along anterio-dorsal and lateral margins; pereonite 1 length about five times width; pereonite 2 twice length of pereonite 1, three-quarters length of pereonite 3; pereonites 4 and 5 largest, about twice length of pereonite 2, pereonite 6 slightly shorter than pereonite 5.

Pleonites together one sixth as long as body; pleonites 1 and 2 similar, together slightly longer than pereonite 6, with long plumose setae extending from margins part way on to the dorso-lateral surface; pleonite 3 slightly shorter than pleonite 2; pleonites 4 and 5 similar, together as long as pleonite 3.

Pleotelson about one-third length of pleonites; posterior margin with pair of short setae central between pair of long setae, about three long and two short setae anterior to articulation with uropod, two lateral setae.

Antennule ( Fig. 16 ). Article 1 about 2.5 times longer than wide, three small pappose setae and about three long setae along outer margin and two clusters of several simple setae with pappose seta distally; article 2 about one-third length of article 1, about 1.5 times longer than wide, with clusters of about five simple setae and about five simple setae plus pappose seta distally; article 3 about half length of article 2, with about five setae distally; article 4 greatly reduced and cap-shaped, with numerous long setae and five aesthetascs.

Antenna ( Fig. 16 ). Article 1 as long as wide, lacking setae; article 2 more than twice length of article 1, with two to four small setae on outer margin and two distal setae; article 3 half length of article 2, lacking setae; article 4 2.5 times length of article 3, with about six long distal simple setae and a pappose seta; article 5 two-thirds length of article 4, with about four simple distal setae and two pappose setae; sixth and seventh articles greatly reduced, much wider than long, with numerous long setae.

Mouthparts ( Fig. 17 ). Labrum carpeted by fine setae, longest setae associated with distal lateral margins.

Left mandible with lacinia mobilis reduced to pointed peg-like process with short spiniform accessory seta, pars incisiva smooth and acutely-pointed, pars molaris broad and corrugated; right mandible with lacinia mobilis reduced and thorn-like, lacking accessory seta, pars incisiva bifurcated, pars molaris broad and corrugated.

Labium with inner and outer lobes covered in fine setae distally, outer lobe with small elongate terminal process and small spines projecting from proximal lateral margins.

Maxillule endite with eight large terminal spiniform setae, and cluster of fine setae on outer margin near base of spinous setae; palp with eight long simple setae.

Maxilliped coxa and basis not joined medially; coxa with three large proximo-medial setae; basis with two distal setae; endite finely setulose marginally, with two short spiniform setae distal near medial margin, two short spiniform setae medial on distal margin, and two distal circumplumose setae that are about onequarter length of simple setae on inner margin of palp; palp with four articles, article 1 width similar to length with two long setae distally on indented outer margin, article 2 slightly longer than article 1 with single seta on outer margin, four or five long setae extending distally in a row from midway near inner margin, three long distal setae near articulation with article 3, and three long setae on distal inner margin, article 3 slightly shorter in length than article 2, fringed with two rows of about seven long setae along inner margin, article 4 approximately two-thirds length of article 3 with two rows of about six long setae distally on inner margin and single seta on outer margin.

Epignath with terminal circumplumose seta and fringed by fine setules.

Cheliped ( Fig. 16 ). Basis longer than wide with distal seta near ventral margin; merus triangular with group of about three setae two-thirds distance along ventral margin, one or two setae distal on dorsal margin; carpus similar in length to basis, with three setae distal on ventral margin, three setae distal on dorsal margin, and seta midway along dorsal margin; propodus similar in length to carpus, with large terminal spiniform seta, about seven setae midway along ventral margin, about eight setae near dorsal margin of fixed finger and three simple setae and single pappose seta near articulation with dactylus; dactylus with row of about 14 very short setae along ventral margin, unguis short and solid, about one-fifth total length of dactylus.

Pereopod 1 ( Fig. 18 ). Coxa produced into anterior process with five setae; basis length approximately six times width; merus about one-quarter length of basis; carpus 1.5 times length of merus; propodus almost length of merus and carpus together, with about six setae near distal ventral margin, long seta near distal dorsal margin and pappose seta; unguis three-fifths length of dactylus.

Pereopods 2 and 3 ( Fig. 18 ). Similar; basis width between one-third and one-quarter length, slightly shorter than merus, carpus and propodus together; merus two-fifths length of basis, with two short spiniform setae and about three simple setae distal on ventral margin and simple seta dorso-distally; carpus two-thirds length of merus, eight to ten serrated spiniform setae near distal margin with dorsal spiniform seta longest; propodus 1.5 times length of carpus, with pappose seta, several distal setae and three setae evenly spaced along ventral margin; unguis three-fifths length of dactylus.

Pereopods 4 and 5 ( Fig. 18 ). Similar; basis length 2.3 times width; merus two-fifths length of basis, with two short spiniform setae and about three simple setae distal on ventral margin and about four simple seta dorso-distally; carpus with two parallel rows of six or seven serrated spiniform setae and about four longer simple setae near distal margin; propodus 1.2 times length of merus, with about four setae on ventral margin and pappose seta plus two long simple setae distal near dorsal margin; unguis merged into claw-like dactylus, with lateral comb-like row of about six flattened setae.

Pereopod 6 ( Fig. 18 ). Basis length 2.3 times width; merus two-fifths length of basis, with two short spiniform setae and about three simple setae distal on ventral margin and about four simple seta dorso-distally; carpus with two parallel rows of about seven serrated spiniform setae and four long simple setae near distal margin; propodus with distal comb-like row of about ten flattened denticulate setae and dorso-distal group of about five slightly longer denticulate setae, a pappose seta and pair of long simple setae; dactylus with lateral comb-like row of about eight flattened setae.

Pleopods 1–3 ( Fig. 18 ). Similar; basal article with about eight plumose setae along outer margin and one plumose seta on inner margin; exopod with about 36 plumose setae along outer margin; endopod with six plumose setae along inner margin, large terminal circumplumose seta and about eighteen plumose setae along outer margin.

Uropod ( Fig. 18 ). Seven articles; basal article length nearly twice width, with about six very long distal setae; article 2 half length of basal article; articles 3, 4, 5 and 6 with length similar to article 2, up to eight long simple setae and pappose seta distally; article 7 reduced to about one-third length of article 6, with about seven very long terminal setae.

MALE. Similar to female, other than

Antennule ( Fig. 16 ). Basal article length about four times width, article 2 length almost twice width, terminal article with six to eight projecting aesthetascs.

Antenna ( Fig. 16 ). Articles proportionately longer than in female, article 2 length about twice width.

Cheliped ( Fig. 16 ). Articles with greater width relative to length than female, basis and carpus length equal to width.

Etymology. Named after Susan Laurie-Bourque, in recognition to her artistic skills and invaluable help with this study.

Distribution. Perth to Canal Rocks, WA. 5–6 m depth.

Remarks. The combination of shape of mandibles, relatively low number of aesthetascs on antennule, uropod with seven articles, and presence of five setae on coxa of pereopod 1 separate this species from all others in the genus. Zeuxoides lauriebourqueae shows greatest similarity with another southwestern Australian species Zeuxoides casanuda , differing primarily in lesser reduction of lacinia mobilis of mandibles, more numerous spiniform setae on carpus of pereopods 2–6, greater number of terminal setae on maxillule palp, and pleopod endopod with six rather than four plumose setae along inner margin. It differs from Zeuxo lasti primarily in the more reduced character of the mandibles, narrower body proportions, details of setation, and lack of pigmentation on pereonites 1 and 2.

Figures

FIGURE 16. Zeuxoides lauriebourqueae n. sp. Canal Rocks, WA. Female dorsal (holotype), male dorsal (paratype; pigmentation not shown), antennules (A1), antennae (A2), chelipeds (CH), pleotelson (Plt). Scale units 0.1 mm (appendages) and 1 mm (dorsal).

FIGURE 17. Zeuxoides lauriebourqueae n. sp. Canal Rocks, WA. Labrum (L), left mandible (Mdl), right mandible (Mdr), labium (La), maxillule (Mx), maxilliped (Mxp), epignath (E). Scale units 0.1 mm.

FIGURE 18. Zeuxoides lauriebourqueae n. sp. Canal Rocks, WA. Pereopods 1–6 (P1–P6), pleopod (Pl), uropod (U). Scale units 0.1 mm.