Zeuxoides rimuwhero, Bird, Graham J, 2008

Bird, Graham J, 2008, Untying the Gordian Knot: on Tanais novaezealandiae Thomson (Crustacea, Tanaidacea, Tanaidae) from New Zealand, with descriptions of two new Zeuxoides species, Zootaxa 1877, pp. 1-36 : 26-34

Zeuxoides rimuwhero n.sp.

Figs 13–17

Material examined. Holotype: preparatory Ψ, 3.22 mm, GJB/1-07 ( NMNZ Cr. 012181).

Allotype: ɗ 2.51 mm, GJB/1-07 ( NMNZ Cr. 012179).

Paratypes: two prep. ΨΨ, two ovig. ΨΨ, three prep. ɗɗ, three ɗɗ GJB/1-07 (NMNZ Cr. 012180).

Additional material: seven neuters (one on microslide), two ɗɗ, GJB/1-05; one manca-3, one neuter, two prep. ΨΨ, (one on microslide), three ovig. ΨΨ, one ɗ, GJB/2-05; six manca-2, one manca-3, five neuters, four prep. ɗɗ, GJB/3-05; two manca-3, eleven neuters, one ɗ, GJB/4-05; 17 n, six prep. ΨΨ, 31 prep. ɗɗ, five ɗɗ GJB/1-07 ( NIWA.44927); nine neuters, two prep. ΨΨ, two ovig. ΨΨ, four prep. ɗɗ, two ɗɗ, GJB/2-07; 14 neuters, four prep. ΨΨ, seven prep. ɗɗ, one ɗ, GJB/3-07; two ɗɗ, GJB/4-07; one ovig. Ψ, 2BLU105-TN ( NIWA.44906); one prep. Ψ, one ovig. Ψ, 2LYT011-TN ( NIWA.44907); one ɗ, 2LYT042-TN ( NIWA.44908); three prep. ΨΨ, one ovig. Ψ, one ɗ, 1STW181-TN ( NIWA.44909); one neuter, one prep. ɗ, three ɗɗ, 1STW233-TN ( NIWA.44910); one neuter, one ɗ, NMNZ. Cr. 012191; four neuters, three prep. ΨΨ, two prep. ɗɗ, four ɗɗ, NMNZ Cr. 012140; two ɗɗ, SA-866 ( NMNZ Cr.12149); three neuters, one prep. Ψ, two prep. ɗɗ, SA-3492 ( NMNZ Cr. 012148); one?neuter, one prep. Ψ, one ovig. Ψ, NIWA.27332; two prep. ΨΨ, NIWA.27336; two individuals, probably G.M. Thomson collection ( NIWA.44929).

Diagnosis. Zeuxoides with cephalothorax longer than pereonites 1–3; dorso-lateral plumose setae on pleonites 1–3. Antennule articles 3–4 more than half as long as article-2; six aesthetascs on terminal article. Mandibles without setal row, right lacinia mobilis small, spiniform, with bifid incisor, left lacinia tooth-like. Pereopod-1 coxa with up to three or four-cusped spur; pereopods 2–3 carpus with eight or nine spines; pereopods 4–6 carpus with twelve spines. Pleopod basis with one inner and eight outer plumose setae, exopod with five inner setae. Uropod six or seven articled. Sexual dimorphism weak to moderate, male slightly stouter; antennule slightly longer, with six to eight terminal aesthetascs; stouter cheliped.

Description. Female: Body ( Fig. 13 A) about 5.2 times longer than broad, length 3.00– 5.68 mm (holotype 3.22 mm). Pigmentation dark purple-brown scattered on most of dorsal surfaces, with patterns of un-pigmented spots and lacunae. Cephalothorax just longer than broad, longer than pereonites 1–3 combined, with a few setae posterior to the eye-lobe and mid-laterally; rostrum weakly triangular. Pereon about 50% of body length, pereonites 1–3 progressively longer, pereonite-1 with lateral and dorso-lateral setae, pereonites 2–3 with lateral setal groups; pereonites 4–5 equally long, pereonite-6 just longer than pereonite-3; other setation as figured. Pleon ( Fig. 13 B) about 19% of total body length, pleonites 1–3 progressively smaller, with about one, seven and five lateral plumose setae and about four or five plumose setae in dorso-lateral clusters; other setation as figured; pleonites 4–5 short and broad, with dorsal and lateral setal groups. Pleotelson ( Fig. 13 B) 0.44 times as long as broad; with two long apical setae and two groups of (three and four) setae on each lateral margin.

Antennule ( Fig. 14 A) 0.6 times as long as cephalothorax, article-1 2.4 times longer than broad, 2.6 times longer than article-2, with several simple and pinnate lateral setae and inner and outer distal setal groups; article-2 with about seven inner and seven outer simple setae, in addition to several pinnate setae; article-3 0.6 times as long as article-2, with several simple and pinnate setae; article-4 very short, with about seven long setae, about six shorter setae and six aesthetascs. Antenna ( Fig. 14 B) just longer than antennule; article-1 short; article-2 longer than broad, with one dorsal, two lateral and four ventral setae, with dorsal spinulose margin; article-3 short, without setae; article-4 a proximal setae and about eight distal setae; article-5 with several simple and pinnate setae; article-6 short, with at least eight setae; article-7 cap-like with at least twelve terminal setae.

Labrum ( Fig. 15 A) typical of genus, hood-like and distally setose. Mandibles ( Figs 15 B–C) typical of genus, robust; right mandible with strongly bifid incisor and short spiniform lacinia mobilis; left mandible with tooth-like lacinia mobilis without setal row. Labium ( Fig. 15 D) typical of genus; inner and outer lobes setose, with ‘granular’ spines; outer margin spinose, and with small conical accessory lobe. Maxillule ( Fig. 15 E) typical of genus; palp with eight long terminal setae; endite with seven terminal spines (one thinner than rest) and distal array of setae. Maxilliped ( Figs 15 F–H) typical, robust; each basis elongate, with proximal lobe with two setae, distal margin with one setae; endites with setose lateral and distal margin, each with two coupling hooks, two spiniform disto-medial setae and inner distal margin with two large, articulated pinnate setae; palps typical, article-2 with three long distal pectinate setae in addition to inner setal rows. Epignath ( Fig. 15 I) typical of genus.

Cheliped ( Figs 16 A–B) typical of genus; sclerite narrowly triangular; basis with one ventral seta, and one seta near articulation with sclerite; merus with three setae near articulation with carpus, and four ventral setae; carpus 1.5 times longer than broad, with disto-dorsal and ventral setal groups (as figured); chela about twice as long as broad, propodus with five outer setae near dactylus and two on inner face; fixed finger with seven ventral setae and six setae on outer incisive margin, two on inner; dactylus with incisive margin set with small spines, and a small anterior seta.

Pereopod-1 ( Figs 16 C–D) Coxa with distinct anterior four-cusped spur, with five setae; ischio-basis 4.4 times longer than broad, with three simple and one pinnate proximal setae, and two unequal disto-ventral setae; merus short, with single dorsal and ventral setae; carpus 1.1 times as long as merus, with three dorsal and two ventral setae; propodus 0.9 times as long as merus and carpus together, with strong anterior seta, one dorso-terminal seta and seven ventral setae; dactylus and unguis about a half length of propodus, unguis with hollow (spinning) tip.

Pereopod-2 ( Figs 17 A–B) much stronger than pereopod-1, coxa annular, with three setae; ischio-basis with three proximal setae and five ventro-terminal setae; merus over half length of ischio-basis, with two dorsal and seven ventral setae and a ventro-lateral complex spine; carpus shorter than merus, 1.4 times longer than broad, with about four dorsal and three ventral setae and nine complex spines; propodus twice as long as carpus, with six ventral setae and two dorso-terminal setae; dactylus and unguis about half length of propodus, dactylus with accessory seta and unguis with spinning pore.

Pereopod-3 ( Figs 17 C–E) similar to pereopod-2, but ischio-basis with four proximal setae and four distal setae; merus shorter; carpus only as long as broad, with eight complex spines; propodus shorter, with seven ventral setae.

Pereopod-4 ( Figs 17 F–H) ischio-basis broader than in pereopods 1-3, with two proximal seta, one ventral pinnate seta and five distal setae; merus about twice as long as broad, with groups of six dorsal and four ventral setae and two complex spines; carpus as long as merus, with dorsal paired groups each of three or four setae, and twelve complex spines; propodus longer than carpus, with four ventral setae and four distal setae, one pair of which are long and strong; claw typical of genus.

Pereopod-5 ( Figs 17 I–J) Similar to pereopod-4, but ischio-basis with two pinnate setae.

Pereopod-6 ( Figs 17 K–M) Similar to pereopods 4–5 but propodus with disto-lateral comb of about ten blade-shaped spines.

Pleopod ( Fig. 14 C) All of similar size; basis broader than rami, with one inner and eight outer plumose setae; endopod with five setae on outer margin, and about 25 on inner margin, thicker distally; exopod with about 38 marginal setae.

Uropod ( Fig. 13 C) Robust, six or seven-articled; basis with about four inner and three outer distal setae; endopod with short articles, articles 1, 2 and 5, stouter than articles 3–4, with several long distal setae (about seven, eight, ten and eight respectively), article-6 very short with about five long terminal setae.

Manca-2: Length 0.72–0.9mm, uropod four-articled, terminal article not cap-like.

Manca-3: Length 1.14–1.32 mm, uropod four-articled, terminal article not cap-like.

Non-ovigerous/neuter: Length 1.21–3.87 mm. Pereopod-1 coxa ( Fig. 16 E) with two or three-cusped spur. Uropod four to seven-articled, smallest individuals without cap-like terminal article.

Preparatory female: Length 2.51–5.13 mm. Pereopod-1 coxa with two to four -cusped spur. Uropod six, seven or eight-articled; oostegite buds posterior to pereopod-4 attachment.

Preparatory male: Length 1.56–2.80 mm. Pereopod-1 coxa with a two or three-cusped spur. Uropod five or six-articled, rarely seven-articled.

Male ( Fig. 13 D): Slightly more robust and compact than female, 4.5 times longer than broad (although dependant on relaxation/contraction); length 2.08–3.83 mm. Antennule ( Fig. 14 D) only article-1 slightly more elongated than in female, with six to eight terminal aesthetascs. Cheliped ( Fig. 16 F) carpus stouter, propodus compact, incisive margin of fixed finger and dactylus almost straight, minutely serrate or corrugated. Pereopod-1 coxa with a two or three-cusped spur ( Fig. 16 G). Uropod ( Fig. 14 E) six or seven articled.

Etymology: Combination of Te reo Mãori ‘rimu’ = ‘seaweed’ and ‘whero’ = ‘red’, alluding to principal habitat.

Type locality: Pukerua Bay, Kapiti Coast, New Zealand, in Corallina , filamentous red algal turf and other encrusts on rock platforms in lower eulittoral (‘ Corallina -Hormosira banksii ’ zone).

Distribution: Recorded from Snares Island, Fjiordland, Stewart Island, Bluff, Lyttelton, Kaikoura, Wellington and the West coast of the North Island from Plimmerton to New Plymouth; littoral or shallow sublittoral.

Remarks: This is generally a smaller and more gracile species than Z. aka n.sp., with more slender antennules (especially longer articles 3–4) and uropods, a more cuspate pereopod-1 coxal spur, and mandibles with even greater reduction of the lacinia mobilis. It appears to be closest to the Tasmanian Z. mawbeyi but Z. rimuwhero has the antennal article-4 with a proximal seta, coarser labial setation, eight maxillule palp setae, the cheliped carpus and ventral fixed finger are more setose, and there are more carpal spines on pereopods 2–3. From Z. helleri this species is distinguished by its proportionately larger cephalothorax, the lack of the setal row on the mandibles, and the left lacinia is broader and more rectangular. Zeuxoides rimuwhero also attains six-articled uropods at much smaller sizes than Z. helleri , i.e. between 1.6–3.2 mm and has seven, or even eight between 2.3–5.6 mm, compared to Sieg’s few specimens of Z. helleri of between 5–6 mm.

The manca and very small neuter stages of this species indicate that the reduced terminal uropod article state is not expressed from the onset, but appears at a certain moult stage later in development. A wide range in size (age?) is also observed but this may be related to habitat stability.

At the Titahi Bay-Pukerua Bay intertidal localities Z. rimuwhero occurs with other small apseudomorphan and tanaidomorphan species: Apseudomorpha timaruvia (Chilton) , Cycloapseudes sp, Metapseudes aucklandiae Gardiner , Konarus sp. and a Paratanais species.

Figures

FIGURE 13 Zeuxoides rimuwhero n. sp. Holotype preparatory Ψ (3.22 mm; Pukerua Bay, Stn GJB / 1 - 07; NMNZ Cr. 012181): A, dorsal view, typical pigmentation shown; B, pleon and pleotelson; C, uropod. Allotype ♂ (2.51 mm; Pukerua Bay, Stn GJB / 1 - 07; NMNZ Cr. 012179): D, dorsal view, pigmentation not shown. Scale bar = 1 mm for A and D, 0.4 mm for B, 0.3 mm for C.

FIGURE 14 Zeuxoides rimuwhero n. sp. Paratype preparatory Ψ (Pukerua Bay): A, antennule; B, antenna; C, pleopod. Allotype ♂: D, antennule; E, uropod. Scale bar = 0.25 mm.

FIGURE 15 Zeuxoides rimuwhero n. sp. Paratype preparatory Ψ (Pukerua Bay): A, labrum; B – C right and left mandibles respectively, with detail of lacinia mobilis and setal row; D, labium; E, maxillule; F, maxilliped (palps omitted); G, maxilliped palp; H, endite, inner face. I, epignath. Scale bar = 0.5 mm for F, 0.25 mm for A – E, G – I.

FIGURE 16 Zeuxoides rimuwhero n. sp. Paratype preparatory Ψ (Pukerua Bay): A, cheliped; B, inner view of cheliped fixed finger; C, pereopod- 1; D, pereopod- 1 coxal spur. Neuter (2.5 mm): E, pereopod- 1 coxal spur. Paratype ♂ (3.05 mm; Pukerua Bay )): F, cheliped; G, pereopod- 1 coxal spur. Scale bar = 0.25 mm for A – C and F; 0.125 mm for D, E and G.

FIGURE 17 Zeuxoides rimuwhero n. sp. Paratype preparatory Ψ (Pukerua Bay): A, pereopod- 2; B, same, inner carpal setation; C, pereopod- 3; D – E, same, inner carpal setation and dactylus / unguis; F, pereopod- 4; G – H, same, inner carpal setation and claw; I, pereopod- 5; J, same, inner carpal setation; K, pereopod- 6; L – M, same, inner carpal setation and claw. Scale bar = 0.25 mm for A – G, I – L, 0.16 mm for H and M.