Triparatanais polynesiensis Bird 2019, n. sp.
Creators: name: Bird, Graham J.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Tanaidacea
Paratanaidae
Triparatanais
Triparatanais polynesiensis

description: Triparatanais polynesiensis n. sp.
(Figs 19–21)
Material examined. Holotype —non-ov. ♀, 3.0 mm, P. 102345, Stn 64-2, Morane, 23° 09' 59" S 137° 09' 16" W, rubble, 19 m, 10 October 2014, A. Berthelsen, A. Reid, S.J. Keable, and C. Bedford.
Paratypes —AUSTRAL ISLANDS: one non-ov. ♀ P. 102349, Stn 6.6; one prep. ♂ (?) P.99214, Stn 9-1; two non-ov. ♀♀ P.99212, Stn 28-1; one non-ov. ♀, one ov. ♀ P. 102344, Stn 28-61; two non-ov. ♀♀ MA73586, Stn 54- 2; one manca-III, four non-ov. ♀♀ P. 102343, Stn 54-5; one non-ov. ♀ P.99211, Stn 54-5.
MORANE: one ov. ♀ P. 102348, Stn 56-2; two non-ov. ♀♀ P.99215, Stn 59-2; four non-ov. ♀♀, one prep. ♀ MA73588, four non-ov. ♀♀, one prep. ♀, one post-ov. ♀ P. 102346, one non-ov. ♀, 3.0 mm, dissected on three microslides P. 102347, P.102347.001, one non-ov. ♀ P. 102351, Stn 64-2.
Diagnosis. Antennule article-3 four times longer than article-2. Cheliped propodus with two ventral setae. Pereopods 2–3 ischium with spine, merus with inferodistal spine and seta, carpus with three crotchets and seta. Pereopods 4–6 carpus with four crotchets and seta. Pereopod-6 propodus with three dorsodistal spines.
Etymology. Commonly-used form of Polynesia with Latin suffix - ensis, denoting of the place.
Description. Holotype preparatory female, 3.0 mm (P. 102345). Habitus (Fig. 19A–B) slender, 7.8 times ltb (extended, ca. 6.6 times ltb contracted). Cephalothorax 1.2 times ltb, just longer than pereonites 1–2 combined (contracted), with single anterolateral setae posterior to eyes. Pereon with all pereonites shorter than broad, pereonites 1 and 6 shortest, pereonites 2–3 subequal, pereonites 4–5 subequal, longest; pereonite-1 sternite (Fig. 19C–D) with median process separating two anterior semicircular depressions; all pereonites with two anterodorsal setae, pereonites 4–6 also with two posterolateral setae. Pleon 1.26 times ltb, about 19% of body length (contracted), pleonites equal in length, with slightly raised sternites. Pleotelson (Fig. 19E–F) shorter than pleonites 4–5 combined, with two posterolateral setae, two posterodistal setae and two PSS, and two deflected apical setae.
Paratype non-ovigerous female, 3.0 mm (P. 102347, P.102347.001). Antennule (Fig. 19G) just shorter than cephalothorax, 4.9 times ltb; article-1 with internal distal division, 1.3 times longer than articles 2–3 combined, 2.7 times ltb, lateral margin with three proximal PSS, one seta and a PSS at midlength, and distal seta and three PSS, mesial margin with distal seta; article-2 shorter than broad, with lateral and mesial single setae; article-3 four times length of article-2, 3.8 times ltb, with apical spur, without distinct cap-like segment, with five unequal simple setae and one aesthetasc. Antenna (Fig. 19H) article-1 as long as broad, naked; article-2 slightly inflated, 1.4 times ltb, twice length of article-3, with dorsodistal seta, distolateral seta, and small ventrodistal seta; article-3 just longer than broad, with acute superodistal spine; article-4 length of article-2, 2.8 times ltb, with two unequal setae and three PSS; article-5 0.6 times length of article-4, 2.7 times ltb, with long distal seta; article-6 cap-like, with one short and four long setae.
Mouthparts. Labrum (Fig. 20A) distally setulate, hood-like. Mandibles (Fig. 20B–C) robust, right incisor weakly crenate, entire, molar three-lobed; left incisor weakly crenate, lacinia broad, weakly flared and distally crenate, molar with granular triturative surface and row of spines, lobed apex with notch. Labium (Fig. 20D) inner lobes with weak medial crenulation, lateral margin with three spinules and several setules, outer lobes much reduced with two lateral spinules and several setules. Maxillule (Fig. 20E–F) endite with distal setules, with nine terminal spines, three of which are weakly hooked. Maxilla (Fig. 20G) elongate, subovate.
Maxillipeds (Fig. 20H) typical paratanaidin. Endites with distomedial flat tubercles rounded, medial seta length of endite. Palp article-1 shorter than broad, naked; article-2 lateral seta shorter than article, mesial margin with long simple seta, one weakly serrulate seta and pectinate seta; article-3 with mesial apophysis bearing three serrulate setae, with one inner (oral) simple seta; article-4 with proximomesial setules, one small superior seta and five distal serrulate setae. Epignath not observed.
Cheliped (Figs 19C; 20J–K) with coxal sclerite extending to posterior margin of cephalothorax (Fig. 19C); basis 1.5 times ltb, posterior lobe just shorter than anterior mass, latter with dorsodistal seta; merus typical, with ventrodistal seta; carpus 1.8 times ltb, with two dorsal and two ventral setae. Chela as long as, but narrower than, carpus; propodus 2.4 times ltb, palm 2.1 times longer than fixed finger; palm with two ventrodistal setae, bayonetshaped spine near articulation with dactylus, and comb of four dorsomesial spines; fixed finger with weakly lobed incisive margin and three blunt setae, middle longest, terminal spine narrow; dactylus strong, with two flat and arcuate spines on incisive margin and blunt proximomesial spine.
Pereopod-1 (Fig. 21A) coxa with seta; basis arcuate, 3.8 times ltb, with superoproximal seta; ischium with small seta; merus 2.4 times ltb, with two inferodistal and two superodistal setae; carpus just shorter than merus, twice length of broad, with two superodistal setae and one inferodistal seta; propodus 1.6 times longer than carpus, 4.6 times ltb, with two unequal superodistal setae and one inferodistal seta; dactylus shorter than unguis, with accessory seta; unguis together with dactylus 0.9 times length of propodus.
Pereopod-2 (Fig. 21B) coxa with seta; basis broader than pereopod-1, 2.7 times ltb, with superoproximal seta; ischium with spine; merus 1.6 times ltb, with inferodistal crotchet and seta (mesial); carpus length of merus, 1.5 times ltb, with superodistal crotchet, and two unequal inferodistal crotchets; propodus just shorter than merus and carpus combined, three times ltb, with two unequal superodistal setae and longer inferodistal seta; dactylus with accessory seta, shorter than unguis; unguis together with dactylus about 0.8 times length of propodus.
Pereopod-3 (Fig. 21C) like pereopod-2 but slightly shorter overall; basis broader, 2.4 times ltb.
Pereopod-4 (Fig. 21D) coxa annular; basis broader than in pereopods 2–3, 1.6 times ltb, with longitudinal groove on superodistal margin, inferior margin with one simple seta and two PSS; ischium with two unequal setae; merus sub-geniculate, with two unequal inferodistal crotchets, and spinulate inferior margin; carpus just shorter than merus, 1.3 times ltb, distally wider, with superodistal seta, three unequal distal crotchets, and one inferodistal molariform crotchet, inferior margin with paired spinulate ridges; propodus longer than carpus, 3.3 times ltb, widest at midlength with superior PSS, with superodistal slender spine and two highly unequal inferodistal crotchets; dactylus and unguis claw-like, unguis half length of dactylus, together 0.6 times length of propodus.
Pereopod-5 (Fig. 21E) as pereopod-4.
Pereopod-6 (Fig. 21F) like pereopods 4–5 but basis with one simple seta and one PSS on inferior margin; propodus without superior PSS and with three slender superodistal spines.
Pleopod (Fig. 21G–H) peduncle just longer than broad; rami unequal in length and proportion; endopod 2.2 times ltb, with distomesial seta, proximolateral seta circumplumose, separated by gap from fringe of ten distolateral plumose setae, distalmost whip-like, and mesial margin finely setulate; exopod longer but as wide as endopod, 3.6 times longer than broad, with proximal plumose seta, and distal fringe of 15 lateral plumose setae.
Uropod (Fig. 21I) peduncle just longer than broad; endopod two-segmented, 2.2 times longer than peduncle, three times ltb, with distal seta and two PSS, segment-2 about 0.6 times as long as segment-1, with five unequal distal setae and two PSS; exopod one-segmented, length of peduncle, 0.8 times length of endopod segment-1, with subdistal seta and two unequal apical setae.
Intraspecific variation. Non-ovigerous and preparatory female. Habitus like holotype female; length 1.30– 3.00 mm (non-ovigerous females, n=17), 3.1 mm (other preparatory female).
Ovigerous female. Habitus like preparatory female but slightly dorso-ventrally compressed and with four pairs of oostegites; length 2.09–2.75 mm (n=3).
Distribution and habitat. Rapa Iti (Austral Islands) and Morane; 1–20 m, from coral rubble, finely-branched coral, coarse sand, and rubble.
Remarks. This species is very like the Indo-Pacific (Andaman Islands) T. meios, although T. polynesiensis n. sp. is larger and the pereopodal setation is more complex (reflected in the diagnosis given above). Bamber & Chatterjee (2010: p.23) suggested that the reduction in the number of setae/spines in T. meios may have been due to its small size (1.29 mm) although difficulty in observing all setation may have contributed. Further material of T. meios would be required to confirm this.
A small paratanaidin swimming male of body length 1.15 mm (P. 102350) was recorded in one sample, Stn 9-1 from the Austral Islands. This may belong to T. polynesiensis, but as no other specimens of this species were present in the sample, it has not been included in the description.
description: Published as part of Bird, Graham J., 2019, Tanaidacea (Crustacea: Peracarida) from the Southern French Polynesia Expedition, 2014. I. Tanaidomorpha, pp. 1-75 in Zootaxa 4548 (1) on pages 40-45, DOI: 10.11646/zootaxa.4548.1.1, http://zenodo.org/record/2584426