Paratanais Dana, 1852

BIRD, GRAHAM J. & BAMBER, ROGER N., 2013, New littoral, shelf, and bathyal Paratanaidae (Crustacea: Peracarida: Tanaidacea) from New Zealand, with descriptions of three new genera, Zootaxa 3676 (1), pp. 1-71 : 21-22

Paratanais Dana, 1852

Larsen (2001): 358 (bibliography to date); Bird & Bamber (2000): 89; Bamber (2005): 709; Bamber (2008): 180; Bamber & Costa (2009): 193; Bird (2011): 25; Larsen (2012): 37.

Composition. [ NZ species in bold]. Paratanais atlanticus Dollfus , P. caterae sp. nov., P. clarkae Bird & Bamber , P. elongatus (Dana) [type species], P. euelpis Barnard , P. gaspodei Bamber , P. hamulus sp. nov., P. hessleri Kudinova-Pasternak , P. impressus Kussakin & Tsareva , P. incomptus sp. nov., P. limicola Harger , P. linearis Haswell , P. maleficus Larsen, 2001 ; P. martinsi Bamber & Costa, 2009 ; P. monodi Makkaveeva , P. oculatus ( Vanhöffen, 1914) ; P. paraoa Bird, 2011 , P. perturbatius Larsen, 2001 ; P.puia sp. nov., P. rigidus Bate & Westwood , P. tanyherpes Błażewicz-Paszkowycz & Bamber, 2012 ; P. tara Bird, 2011 ; P. tenuis Thomson, 1880 ; P. vetinari Bamber, 2005 ; P. wanga Bamber, 2008 .

Distribution. Eastern and western Australia, Brazil, Indonesia, Magellanic South America, Northeast Atlantic (Azores, Great Meteor Seamount), New Zealand, North Pacific, Red Sea, South Africa, South China Sea (including Hong Kong), Southern Ocean (Kerguelen); eulittoral to 903 m.

Remarks. Bird (2011) described two new Paratanais species from littoral and shallow sublittoral habitats in New Zealand, P. paraoa and P. tara , bringing the world’s total number of named species, excepting those five transferred to Aparatanais (see above), to 21 ( Anderson 2012, and later), although not all are Paratanais sensu stricto (see Bird 2011 for comments pertaining to P. tenuis ). Recently Bamber (2012) has synonymised P. pseudomartinsi Larsen, 2012 with P. martinsi . The known NZ Paratanais diversity remains lower than that of Australia, from where seven species have been described to date ( Bamber 2008: 217; Błażewicz-Paszkowycz & Bamber, 2012).

Species discrimination and identification can be extremely difficult in this genus, especially if key characters such as the setation of antennal articles 2–3 or maxilliped palp article-2 cannot be observed without dissection (but removal or mere displacement of one of the chelipeds is a useful option here). Indeed, Larsen (2001) went as far as saying that without molecular analysis several species would not have been recognised but, although often the case, the similarities between the three species under consideration in that paper have been somewhat overstated (see below). However, a similar situation has now been encountered with some of the NZ Paratanais species , namely P. paraoa and near-cryptic/cryptic relatives.

In Bird (2011), it was also mentioned that P. oculatus had been identified from some NZ tanaidacean samples by the late J. Sieg in 1982 (Bird & Webber in prep.). These specimens, registered in both the NIWA and Te Papa collections, were largely from offshore stations and most are included in the accounts of the new species described below. It is not uncommon to find records of described species well away from their type locality, in this instance the Kerguelen Islands ( Vanhöffen 1914; Kussakin 1966; Shiino 1978) and many such records prove to be invalid on examination that is more detailed. With one possible exception (see below), this has proved to be the case with the NZ ‘ P. oculatus ’.

In the following descriptions many characters are common to all the NZ Paratanais species , and indeed to the new NZ and Australian Paratanais and Paratanais -like genera, described herein and do not require repeating. These are effectively ‘implicit characters’ following Poore (2001) on anthuroid isopods. This results in an extended diagnosis but does not necessarily include, or apply to, all Paratanais species.

Diagnosis. Females: Cephalothorax with small triangular rostrum, carapace entire; eyes present, pigmented; single lateral seta posterior to each eyelobe. Pereon of six free cylindrical pereonites, all as long as or shorter than broad, at most pereonites 4–5 longer than broad, pereonite-1 shortest; pereonites 2–6 with two dorsal setae. Pleon of five free subequal pleonites bearing pleopods, plus pleotelson; pleonites 1–4 with a simple seta and a pappose,

articulating lateral seta on each epimeron, pleonite-5 only with short simple seta. Pleotelson not plate-like, semicircular, short, with single seta anterior of each uropod attachment, posterior margin with one or two simple and one PSS on each side of deflexed apex that bears two setae.

Antennule four-articled, with or without distinct cap-like terminal segment; article-1 lateral margin with proximal and distal groups of PSS (usually three per group) and distal seta, medial margin with distal seta; article- 2 distolateral margin with simple seta and one or more short PSS, distomedial margin with seta; article-3 short, annular, with medial and distolateral setae; article-4 slender, with subdistal seta, up to five terminal setae and one aesthetasc (if terminal segment is present most arise from this). Antenna six-articled; articles 2–4 without longitudinal ridge; article-2 larger than article-3, with superodistal seta, and inferior seta (or spine) on apophysis (if this is present); article-3 with superodistal spine; article-4 with one or more simple distal setae and several PSS; article-5 with distal seta; article-6 minute, with about four long setae.

Labrum apically rounded, setose. Mandibles robust, body smooth; left mandible with crenulate lacinia mobilis, molar crushing-grinding type, with spines ventrodistally; right mandible incisor apex bifid, molar without distal spines. Labium simple, two pairs of lobes, outer reduced, finely setose. Maxillule endite distally setulate, with eight or nine terminal spines, palp slender with two long distal setae. Maxilla oval, simple. Maxilliped bases together narrower than expanded endites, unfused distally, with one seta near palp articulation; endites with denticulatesetulate distolateral margin, two close-paired, medial flat tubercles, and single long medial seta; palp article-1 naked, article-2 with one lateral seta, medial margin with one longer seta and two shorter setae; article-3 with four serrulate setae on medial margin (one on oral surface); article-4 with five terminal serrulate setae, one outer simple seta, and several fine proximal-medial setae. Epignath elongate, linguiform.

Cheliped robust, with triangular sclerite that extends to rear of cephalothorax, inserted into dorsum of basis, naked; basis stout, free posterior lobe reaching at least posterior margin of cephalothorax, with superolateral seta (typically); merus triangular, narrow, covering almost whole of inferior margin of carpus, with one seta; carpus with two superior setae and two unequal inferior setae; propodus longer than wide, palm with medial comb of one to four serrate spines, with or without slender sinuate spine near dactylus insertion; fixed finger with distal lamellate apophysis (‘tooth’) on incisive margin (usually reddish-brown), three setae on fixed finger near incisive margin, two setae on inferior margin, and, terminal apophysis distinct (usually reddish-brown); dactylus about as broad as fixed finger, with or without peg-like spines on incisive margin, and with proximomedial serrate spine.

Pereopod-1 longer than others, coxa simple with seta; basis slender, arcuate, with superoproximal or inferior seta; ischium compact with single seta; merus as long as, or longer than, carpus, with oblique articulation with carpus; carpus with at least one distal seta, superior longest; propodus longer and narrower than carpus, with two unequal superodistal setae, and one inferodistal seta; dactylus with proximomedial spine; unguis longer than dactylus. Pereopods 2–3 shorter and more robust than pereopod-1, basis with superoproximal or inferior seta; ischium with one seta; merus expanded distally, with two inferodistal setae or spines; carpus with one superodistal simple seta (in most cases), and three distal serrate spines, superior largest, inferior pair longer than broad, unequal; propodus longer and slightly narrower than carpus, with inferodistal seta and one or two superodistal setae; dactylus and unguis combined shorter than in pereopod-1.

Pereopods 4–6 meral, carpal and propodal spines serrate; basis robust, with at least one mid-inferior PSS; ischium with two setae (usually unequal); merus about as long as carpus, with two inferodistal spines, with or without additional seta; carpus inferior margin with two raised spinulate ridges, with four distal spines and one superodistal stiff seta; propodus with two inferodistal spines, superodistal spine (three in pereopod-6), and midsuperior PSS (but absent on pereopod-6); dactylus and, unguis together claw-like, unguis no more than half as long as dactylus.

Pleopods alike, peduncle naked; rami subovate; endopod with subdistal seta on medial margin with whip-like tip, and several plumose setae along outer margin, with or without setules on medial margin; exopod slightly longer than endopod, proximal seta on outer margin separated from remaining setae.

Uropod peduncle naked, exopod present, one or two-segmented, with mid-lateral and two unequal terminal setae; endopod one or two-segmented, proximal segment (if present) slightly longer than distal segment, and with one disto-medial seta, and two PSS, distal segment with at least three simple setae and one PSS.