Zeuxoides mawbeyi, Edgar, 2008

Edgar, Graham J., 2008, Shallow water Tanaidae (Crustacea: Tanaidacea) of Australia, Zootaxa 1836 (1), pp. 1-92 : 40-46

publication ID	https://doi.org/ 10.11646/zootaxa.1836.1.1
DOI	https://doi.org/10.5281/zenodo.5127390
persistent identifier	https://treatment.plazi.org/id/676CB04D-FFB5-FFD4-FF32-FA77FAEB3387
treatment provided by	Felipe
scientific name	Zeuxoides mawbeyi
status	sp. nov.

Treatment

Zeuxoides mawbeyi View in CoL n. sp.

( Figs 19–21 View FIGURE 19 View FIGURE 20 View FIGURE 21 )

Material examined. Holotype. Ovigerous female ( NMV J56143 View Materials ), 2.7 mm, Cloudy Lagoon , Tasmania (43º26’S 147º13’E), 1 m depth, seagrass ( Heterozostera nigricaulis ) washings, 20 Apr 1992. GoogleMaps

Paratypes. Four ovigerous females, four males, two juveniles ( NMV J56144 View Materials ), holotype location, 29 Mar 1992 .

Other material. Six females, six juveniles, Broulee Island , NSW (35º51’S, 150º11’E), 1 m, macroalgal washings, 29 Sep 1999 GoogleMaps ; two males, three females, Low Head , Tasmania (40º51’S, 146º48’E), 1 m, macrophyte washings, 4 Oct 1999 GoogleMaps ; four males, twelve females, Rocky Cape West , Tasmania (41º04’S, 145º30’E), 1 m, macroalgal washings, 4 Oct 1999 GoogleMaps ; two males, 14 females, Cloudy Bay , Tasmania (43º27’S, 147º13’E), macroalgal washings, 13 Oct 1999 GoogleMaps ; one male, three females, Conningham , Tasmania (43º05’S, 147º17’E), macroalgal washings, 5 Oct 1999 GoogleMaps ; seven females, four juveniles, Tinderbox , Tasmania (43º04’S, 147º19’E), macroalgal washings, 5 Oct 1999 GoogleMaps ; one male, four females Smooth Pool, Eyre Peninsula , SA (32º55’S, 134º04’E), macrophyte washings from low intertidal rockpool, 11 Sep 1993 GoogleMaps .

Diagnosis. With characters of genus. Antennule article 1 about 2.5 times longer than wide in both sexes, terminal article with three or four (female) and six to eight (male) aesthetascs; left mandible with lacinia mobilis reduced and peg-like with acutely-pointed tip, right mandible with lacinia mobilis almost lacking, reduced to very fine thorn; pereopod 1 coxa with three or four setae; pleopod basal article with five or six setae on outer margin, one seta on inner margin, endopod with two to four setae on inner margin; uropod with six articles in mature individuals.

Description. FEMALE.

Body ( Fig. 19 View FIGURE 19 ). Length to 3.0 mm; preserved specimens with mottled pigmentation extending prominently from cephalothorax to pleotelson and on chelipeds, pereopods, antennae and articles 1 and 3 of antennules, often with two prominent dark spots on either side of the pleotelson.

Cephalothorax rounded and narrowing anteriorly in dorsal view, length slightly more than one-fifth body length.

Pereon occupies about 52% of total length; pereonites with several setae along anterio-dorsal and lateral margins; pereonite 1 length about five times width; pereonites 2 and 3 similar, almost twice length of pereonite 1; pereonites 4 and 5 largest, about 1.5 times length of pereonite 2, pereonite 6 three-quarters length of pereonite 5.

Pleonites together one sixth as long as body; pleonites 1 and 2 similar, together as long as 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 length of pleonite 2; posterior margin with pair of short setae central between pair of long setae, three or four long setae plus shorter pappose seta anterior to articulation with uropod, two or three long setae postero-laterally.

Antennule ( Fig. 19 View FIGURE 19 ). Article 1 about 2.4 times longer than wide, three small pappose setae and about three long setae along outer margin and two clusters of about four simple setae with single pappose seta distally; article 2 about one-third length of article 1, length about equal to width, with clusters of about five simple setae and about five simple setae plus pappose seta distally; article 3 about two-thirds length of article 2, with about five setae distally; article 4 greatly reduced and cap-shaped, with numerous long setae and three or four aesthetascs.

Antenna ( Fig. 19 View FIGURE 19 ). Article 1 as long as wide, lacking setae; article 2 about 1.5 times length of article 1, with two setae on outer margin and two distal setae; article 3 half length of article 2, lacking setae; article 4 twice length of article 3, with about five distal setae; article 5 two-thirds length of article 4, with about four simple distal setae; sixth and seventh articles greatly reduced, much wider than long, with about seven long setae.

Mouthparts ( Fig. 20 View FIGURE 20 ). Labrum carpeted by fine setae.

Left mandible with lacinia mobilis reduced and peg-like with acutely-pointed tip and thorn at base, pars incisiva with acutely-pointed tip, pars molaris broad and corrugated; right mandible with lacinia mobilis almost lacking, reduced to very fine thorn, lacking accessory seta, pars incisiva smooth and acute, pars molaris broad and corrugated

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

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

Maxilliped coxa and basis not joined medially; coxa with two large proximo-medial setae; basis finely setulose marginally, with single long seta distally; endite 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 half length of setae on inner margin of palp; palp with four articles, article 1 as long as wide with long seta distal on outer margin, article 2 slightly longer than article 1 with single seta distal on outer margin, five very long setae extending distally in a row from midway along inner margin and two long distal circumplumose setae, article 3 considerably smaller 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. 19 View FIGURE 19 ). Basis longer than wide with distal seta near ventral margin; merus triangular with group of about two setae three-quarters distance along ventral margin, two setae central; carpus similar in length to basis, with about four setae distal on ventral margin, distal dorsal group of four or five setae; propodus similar in length to carpus, with large terminal spiniform seta, about four 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 eight very short setae along ventral margin, unguis short and solid, about one-sixth total length of dactylus.

Pereopod 1 ( Fig. 21 View FIGURE 21 ). Coxa produced into slight anterior bulge with three or four setae; basis length approximately four times width; merus about one-quarter length of basis; carpus 1.5 times length of merus; propodus length of merus and carpus together, with about four setae near distal ventral margin; unguis threefifths length of dactylus.

Pereopods 2 and 3 ( Fig. 21 View FIGURE 21 ). 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 short spiniform seta and about three simple setae distal on ventral margin; carpus between one-half and two-thirds length of merus, with about six serrated spiniform setae along distal margin with dorsal spiniform seta longest; propodus 1.5 times length of carpus, with about four distal setae; unguis three-fifths length of dactylus.

Pereopods 4 and 5 ( Fig. 21 View FIGURE 21 ). Similar; basis width about one-third length; merus two-fifths length of basis, with two short spiniform setae and about three simple setae distal on ventral margin and about two simple setae dorso-distally; carpus with two parallel rows of three and five serrated spiniform setae and about four long simple setae near distal margin; propodus 1.2 times length of merus, with about three 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. 21 View FIGURE 21 ). Basis width about one-third length; merus two-fifths length of basis, with two short spiniform setae and about three simple setae distal on ventral margin and about two simple setae dorso-distally; carpus with two parallel rows of about five spiniform setae near distal margin; propodus with distal comb-like row of about ten flattened denticulate setae and dorso-distal group of about four slightly longer denticulate setae and a long simple seta and pappose seta; dactylus with lateral comb-like rows of about eight flattened setae.

Pleopods 1–3 ( Fig. 21 View FIGURE 21 ). Similar; basal article with five or six plumose setae along outer margin and one plumose seta on inner margin; exopod with about 30 plumose setae along outer margin; endopod with two to four plumose setae along inner margin, large terminal circumplumose seta and about 18 plumose setae along outer margin.

Uropod ( Fig. 21 View FIGURE 21 ). Six articles; basal article length slightly more than twice width, with two long and two short distal setae; article 2 variable in length, but in mature individuals often as long as basal article and with constriction midway, an apparent preliminary stage to segmentation, and about four distal setae; articles 3, 4 and 5 similar in length, with four to six distal setae; article 6 reduced to about one-third length of article 5.

MALE. Similar to female, other than

Body ( Fig. 19 View FIGURE 19 ). Cephalothorax approaching triangular in dorsal view.

Antennule ( Fig. 19 View FIGURE 19 ). Article 1 about 2.5 times longer than wide; article 4 with six to eight terminal aesthetascs.

Cheliped ( Fig. 19 View FIGURE 19 ). All articles proportionately wider than in female; basis and carpus length equal to width; dactylus with unguis about one-tenth total length of dactylus.

Etymology. Named after Ron Mawbey, in recognition of his contribution to the study of Tasmanian fauna over four decades.

Distribution. Eyre Peninsula, SA, to Broulee I, NSW, and Tasmania. 0–5 m depth.

Remarks. Zeuxoides mawbeyi possesses a reduced terminal article in the uropod, but in other morphological features, particularly with respect to details of setation, is allied to species in the genus Zeuxo . Sieg (1980b) regards the presence of numerous aesthetascs in the male antennule as a distinguishing characteristic of Zeuxoides ; however, as few as six are present in Z. mawbeyi whereas up to ten occur in Zeuxo russi .

Zeuxoides mawbeyi shows much greater reduction in the lacinia mobilis of the mandibles than other known species of Zeuxoides , with the exception of southwestern Australian Zeuxoides casanunda . It differs from that species most notably in possessing a uropod with six rather than seven articles, an acutely-pointed lacinia mobilis of left mandible, and in details of setation, including slightly greater number of setae on pleopods ( Bamber, 2005).

This species exhibits considerable variation in setal number and patterns of pigmentation between and within sites. Genetic studies should be undertaken to assess whether the species comprises a complex of more than one cryptic species.