Zeuxo (Parazeuxo) cloacarattus Bamber, 2006, sp. nov.
Creators: name: Bamber, Roger N.
Publisher: name: Zenodo
Year: 2006
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Tanaidacea
Tanaididae
Zeuxo
Zeuxo cloacarattus

description: Zeuxo (Parazeuxo) cloacarattus sp. nov.
Figs. 1–2
Material: Holotype female (MNHN.Ta890), allotype male (MNHN.Ta891), 12 paratype females (1 brooding) and juveniles (MNHN.Ta892); 3 females (1 brooding), 1 male, paratypes (NHM 2005.212–215), 1 female, 1 male dissected. Lagon, New Caledonia, 22º30.15’S 166º26.43’E, 13 m depth on hydroids, 8/11/95. 1 brooding female, paratype (MNHN.Ta893) on Halimeda, and 1 male, 2 females, paratypes (MNHN.Ta894) on Sargassum, Lagon, Ilot Maitre, New Caledonia, 22º19.41’S 166º20.89’E, 20 m depth, 9/ 11/95 (“Station 99”); all coll. Ichiro Takeuchi.
Description of female: typical Zeuxo, body (Figure 1 A) slender, with only slight indication of dorsal black mottling typical of the genus in preserved material; length of holotype 3.6 mm. Cephalothorax subtriangular, 1.1 times as long as wide, with slight rounded rostrum, eyes present, pigmented. Cephalothorax shorter than pereonites 1 to 3 together. Six free pereonites, rounded laterally, with two lateral setae on each side and paired dorsolateral setae towards anterior of pereonite; pereonite 1 shortest, pereonite 2 1.5 times as long as pereonite 1, pereonites 2 to 4 and six subequal, pereonite 5 half as long again (all pereonites respectively 2.8, 1.8, 1.8, 1.6, 1.2 and 1.6 times as wide as long). Pleon of five free pleonites with two lateral setae on each side and paired dorsolateral setae on pleonites 1 to 3, only one lateral seta on pleonites 4 and 5; pleonites 1 to 3 progressively shorter, about three times as wide as long, without transverse dorsal rows of setae, bearing pleopods; pleonites 4 and 5 shorter and narrower, seven times as wide as long, without pleopods. Pleotelson semicircular, 1.3 times as wide as long, distally cleft, with three lateral setae on each side.
Antennule (Figure 1 B) 0.13 times as long as body, of four articles, proximal article three times as long as wide, with one inner and five longer outer laterodistal setae, two outer plumose sensory setae proximally; second article one­third as long as first with single inner distal seta and distal tuft of four outer setae; third article slightly shorter than second with two subdistal and five distal setae; distal article very small, with two distal setae and three aesthetascs.
Antenna (Figure 1 D) of seven articles, second article longest with single setae midventrally and ventrodistally; third article naked, one third length of second with finely serrated inner margin; fourth and fifth articles subequal, two thirds length of second, fourth with four longer and one shorter distal setae, fifth with two longer and three shorter distal setae; sixth less than half length of fifth and with two distal setae, seventh very small with seven distal setae.
Mouthparts. Labrum (Fig. 1 E) rounded, setose. Left mandible (Figure 1 F) with wide lacinia mobilis with minimal distal crenulation and inner tooth, right mandible (Figure 1 G) with small, elongate scale­like lacinia mobilis and outer tooth; pars molaris robust, marginally crenulate. Labium (Figure 1 H) inner lobe finely setose in distal third, outer lobe with midlateral denticulations, labial palp present, elongate, finely setose. Maxillule (Figure 1 I) with eight distal spines, finely setose outer margin, palp as long as endite with three distal setae. Maxilla (Figure 1 L) small, simple, asymmetrical. Maxilliped typical of genus, distal palp article nearly three times as long as wide (Figure 1 J); endites setose, each with three long distal spines projecting ventrally. Epignath (Figure 1 K) typical of genus, elongate with distal spine.
Cheliped (Figure 2 A) comparatively stout, 0.24 times as long as body, basis with single ventrodistal seta; merus triangular with ventral group of four setae; carpus 1.4 times as long as wide, setose as figured; propodus with four ventral setae, group of three setae at insertion of dactylus, fixed finger with two offset rows of four setae along cutting edge, terminal spine on fixed finger subdistal; dactylus with row of submarginal fine setae along cutting edge.
Pereopod 1 (Figure 2 B) longer than others, coxal apophysis triangular, with three setae; basis slender, 3.6 times as long as wide; ischium absent; merus one­quarter length of basis; carpus longer than merus; propodus 1.75 times as long as carpus with ventrodistal tuft of four setae; dactylus with distinct, slender unguis, both together 0.6 times as long as propodus.
Pereopod 2 (Figure 2 C) basis 3.2 times as long as wide; merus half length of basis with pair of ventrodistal short toothed spines; carpus shorter than merus, with three laterodistal tooth­like spines on each side, dorsodistal spine 0.4 times as long as propodus; propodus as long as merus; merus, carpus and propodus with rugose ventral margin; dactylus plus unguis as long as carpus.
Pereopod 3 (Figure 2 D) similar to pereopod 2.
Pereopod 4 (Figure 2 E) basis 3.25 times as long as wide, with three distal setae; merus, carpus and propodus with rugose ventral margin; merus and carpus subequal in length; merus with paired ventrodistal tooth­like spines; carpus three laterodistal tooth­like spines on each side; propodus 1.3 times as long as carpus; dactylus and unguis fused into an claw, curved, with lateral spine combs.
Pereopod 5 (Figure 2 F) as pereopod 4.
Pereopod 6 (Figure 2 G) as pereopod 4, but larger, propodus with distal row of six leaflike spines.
Pleopod (Figure 1 M) basis with single inner and four outer plumose setae; exopod with 24 plumose setae along outer edge; endopod with one inner and eleven outer plumose setae, and distally with shorter, stout, articulate seta.
Uropod (Figure 2 H) uniramous, of six segments including basis, segments two to three times as long as wide, subequal in length; setose as figured.
Description of male: generally similar to but much smaller than female, more robust, cephalothorax as long as pereonites 1 to 3 together; body length of allotype 2 mm. Cheliped proportionately larger than that of female, 0.43 times body length, and as long as of that of female of 1.8 times its body length; carpus 1.13 times as long as wide; propodus with five ventral setae. Antennule (Figure 1 C) more elongate, 0.23 times as long as body; first article 3.1 times as long as wide and 2.7 times as long as second; distal article with five distal setae and eleven aesthetascs.
Etymology: from the Latin cloaca – a sewer, and rattus – a rat (ML), a pun on ‘ seurati ’, the species of Zeuxo to which the present species appears morphologically closest.
Remarks: Zeuxo (Parazeuxo) cloacarattus sp. nov. has the elongate proximal article of the antennule, three times as long as the second, which distinguishes this genus from Anatanais (see Sieg 1980). Since Sieg’s (ibid.) analysis of the genus, five further species of Zeuxo have been described, only one of these, the Hong Kong species Z. (P) zorro Bamber & Bird, 1997 (q.v.), being in the subgenus Parazeuxo.
The only described species of Zeuxo (Parazeuxo) with a single seta on the inner margin of the pleopod endopod and six segments in the uropod (five segments plus basis) is Zeuzo (P.) seurati (Nobili) from Touamoto and Hawaii (incl. Anatanais insularis Miller). That species also has a reduced lacinia mobilis on each mandible.
However, the antennular articles of Z. seurati are more compact than those of Z. cloacarattus (proximal article 2.6 times as long as wide), as are the leg articles; the dorsodistal spine on the carpus of pereopod 2 is half the length of propodus; the cheliped is more slender (carpus 1.5 times as long as wide) with only three ventral setae on the fixed finger; the coxa of pereopod 1 in Z. seurati is more typical of Parazeuxo, being rounded (see Sieg 1980: 221–225, fig. 62) rather than triangular as in the present species.
All specimens were collected from algae or hydroids.
description: Published as part of Bamber, Roger N., 2006, Shallow water tanaidaceans (Crustacea: Peracarida: Tanaidacea) from New Caledonia and the Loyalty Islands, pp. 1-21 in Zootaxa 1108 on pages 2-6, DOI: 10.5281/zenodo.171481