Tanaopsis rawhitia, Bird, 2011

BIRD, GRAHAM J., 2011, Paratanaoidean tanaidaceans (Crustacea: Peracarida) from littoral and shallow sublittoral habitats in New Zealand, with descriptions of three new genera and seven new species, Zootaxa 2891 (1), pp. 1-62 : 54-55

Tanaopsis rawhitia n. sp.

Figs 31–34

Material examined. Holotype: neuter/non-ovigerous female, 2.22 mm GJB/1-09, [CR.21785]. Allotype: swimming male, 1.42 mm GJB/2-09, [CR.21786]. Paratypes: four manca-III, seven neuters [one partly dissected on microslide: CR.21788], one male, GJB/2-09, [CR.2187]. Other material: one neuter, GJB/5-08.

Diagnosis. Female: Habitus: Tanaopsis with pereonites 4–5 as long as broad; pereonite-6 more than half as long as pereonite-5. Mandibles with acuminate molar. Maxilliped basis seta longer than endite. Cheliped fixed finger with bifid sub-terminal spine. Pereopod-1 coxal spur well-developed; pereopod-1 substantially larger than rest. Uropod exopod 1-segmented, as long as ‘segment-1’ of endopod. Male: Habitus swimming form, pereonites 4–6 longer than pereonites 1–3 and pleonites. Cephalothorax about as long as broad. Antennule with 4-segmented flagellum, penultimate segment about as long as last segment. Cheliped fixed finger and dactylus shorter than palm of propodus. Pereopod-1 merus about as long as carpus.

Etymology. From Te reo Māori adjective r ā whiti, ‘eastern’, a reference to the two records on the east coast of North and South Island.

Type locality. Armer’s Bay , Kaikoura, South Island, New Zealand, low intertidal muddy sand and red-algal turf .

Description. Neuter/non-ovigerous female: Habitus ( Fig. 31A ) typical Tanaopsis , small cephalothorax, irregular pereonite outline and wide pleon, slender, 7.5 times ltb; length 1.51–3.33 mm. Cephalothorax pear-shaped, as long as broad, and as long as pereonites 1–2. Pereon 57% of body length; pereonite-1 ( Fig. 31B ) weakly trapezoidal, coxa projecting beyond anterolateral corner; pereonites 2–3 weakly hexagonal; all with rounded lateral corners; pereonite-5 longest; 0.3, 0.58, 0.7, 0.88, 0.98 and 0.64 times ltb respectively. Pleon wider than pereon, 22% of body length, as long as pereonites 5–6; pleonites 1 and 5 longer than 2–4, all with small epimeral seta. Pleotelson ( Figs 31C–D ) as long as pleonite-5 and half of pleonite-4, sub-conical with two posterior dorsal setae, two PSS and four apical setae (two deflexed).

Antennule ( Fig. 31G ) almost as long as cephalothorax; article-1 half total length, with blunt-tipped setae on distal mesial and lateral margins; article-4 as long as article 2–3, with vestige of a small cap-like fifth terminal article; other setation as figured. Antenna ( Fig. 31H ) typical, article-2 larger than article-3, with long superior seta and smaller inferodistal seta; article-3 with long superior seta; article-4 4 times longer than broad, with a mesial PSS, three distal simple and two PSS; article-6 with thick (fused?) seta.

Labrum ( Fig. 32A ) typical, hood shaped. Labium not observed. Mandibles ( Figs 32B–C ) typical, with acuminate molar. Maxillule ( Figs 32D–E ) typical, endite bent at right-angle, with distal setae and six (?) terminal spines,

one much larger than rest. Maxilla not observed. Maxilliped ( Figs 32F–G ) typical; basis seta longer than endite; flared endite with distal seta. Epignath ( Fig. 32H ) typical, thin and strap-like.

Cheliped ( Figs 31E , 32J–M ) typical; coxal sclerite triangular, rear apex meeting posterior of cephalothorax; basis with large free posterior margin, overlapped by pereopod-1, with distolateral seta; merus with one seta; carpus 1.4 times ltb, with two inferior and two superior setae; propodus narrower and slightly longer than carpus, palm not distally wider, with lateral seta near dactylus insertion mesial comb of six spines; fixed finger 0.4 times propodal total length, with three superior distal and two inferior setae, incisive margin with three small distal teeth, bifid distal spine and bifid terminal spine; dactylus with weakly crenulated superior margin, and mesial seta, incisive margin with two small peg-like spines.

Pereopod-1 (Fig. 33A) largest of pereopods; coxa with acuminate spur bearing seta; basis with proximal seta; ischium with one seta; merus naked; carpus as long as merus, with three distal setae; propodus longer than merus and carpus together, with superior microtrichia, two superior distal and one inferodistal seta; dactylus shorter than unguis, together longer than propodus. Pereopod-2 (Fig. 33B) about 0.75 times length of pereopod-1; coxa annular; basis four times ltb, ischium with one seta; merus as long as broad, naked; carpus just longer than merus, with three distal setae; propodus longer than merus and carpus, similar to that of pereopod-1; dactylus and unguis just longer than propodus. Pereopod-3 (Fig. 33C) similar to pereopod-2 but shorter; basis 3.5 times ltb; merus, carpus, propodus and dactylus-unguis all shorter.

Pereopod-4 (Figs 33D–E) similar in length to pereopod-3; basis stouter, 2.9 times ltb, with an inferodistal PSS; ischium with two setae; merus longer than broad, with two stout inferodistal spines; carpus as long as merus, with three distal spines and one superior distal seta; propodus longer than carpus, superior margin with microtrichia and a PSS, with one superior distal and two inferodistal spines; dactylus longer than unguis, claw-like, together half as long as propodus. Pereopod-5 (Fig. 33F) similar to pereopod-4 but basis with two inferior PSS. Pereopod-6 (Fig. 33G) similar to pereopods 4–5 but basis with simple inferior seta, propodus with three pectinate superior distal spines.

Pleopod ( Fig. 32N ) typical, endopod shorter and wider than exopod, with distomesial seta and 8–9 distolateral setae, with naked proximal lateral margin; exopod lateral margin with continuous fringe of 25–26 setae.

Uropod ( Fig. 31F ) typical, exopod half length of endopod; endopod with pseudo-segmentation marked by two PSS.

Manca-III: Habitus stouter than non-ov. female; length 1.13–1.22 mm.

Male: Habitus ( Fig. 34A ) typical swimming male, fairly stout, 4.6 times ltb, length 1.42–1.43 mm. Cephalothorax as long as broad, flask-shaped, epistome ( Fig. 34B ) prominent, acuminate. Pereon 46% of body length, pereonites 1–3 subequal, pereonites 4–5 twice as long as 1–3. Pleon not much wider than pereon, 27% of total length. Pleotelson ( Fig. 34C ) conical, with more prominent apical process than female.

Antennule ( Fig. 34D ) peduncle article-1 stout, about 40% of total length; flagellum segment-1 very short, segment-3 longer than segment-2, subequal to segment-4; segments 1-3 with inferior bundle of aesthetascs; other setation as figured.

Mouthparts (not figured) typical of genus, reduced.

Cheliped ( Figs 34E–F ) similar to female but carpus stouter, 1.2 times ltb; palm with mesial comb of thirteen spines.

Pereopod-1 ( Fig. 34G ) similar to female but coxa without spur, other articles more slender; carpal and propodal setae longer; dactylus and unguis only as long as propodus. Pereopod-3 ( Fig. 34H ) similar to female but more slender. Pereopod-4 ( Fig. 34 ) similar to female but basis with two pinnate setae; meral and carpal spines more slen- der.

Pleopod (not figured) with setae longer than in female.

Uropod ( Fig. 34C ) exopod 2-segmented; endopod 2-segment, segment-1 with proximal band of PSS.

Remarks. This New Zealand species is very similar to the West European T. graciloides , differing in the presence of a mandibular molar. If using the key given by Sieg & Dojiri (1991) T. rawhitia n. sp. would appear in couplet ‘5’, close to the undescribed Antarctic species, but would be distinguished by the bifid sub-terminal spine on the cheliped fixed finger. The Australian species T. canaipa is easily distinguished by, among other things, its long cephalothorax, different pereonite shapes and 2-segmented uropod exopod. The uropod endopod of T. rawhitia is essentially 1-segmented or with barely visible pseudo-segmentation, it has gracile chela, and among the largest pereopod-1 coxal spur within the genus. Although substantial, the size disparity of pereopod-1 to the other pereopods is not as great as in T. chotkarakde Bird & Bamber, 2000 .

Distribution and ecology. Aside from the type locality, this new Tanaopsis species has been recorded from Castlepoint, Wairarapa on the east coast of North Island. As with other species in this study, it may be quite common in sandy low intertidal and subtidal habitats.

Figures

FIGURE 31. Tanaopsis rawhitia n. sp. Holotype non-ovigerous female: A dorsum; B pereonite-1 and coxal spur; C pleotelson;

FIGURE 32. Tanaopsis rawhitia n. sp. Paratype non-ovigerous female: A labrum, lateral; B–C left and right mandibles; D

FIGURE 34. Tanaopsis rawhitia n. sp. Allotype swimming male: A dorsum; B cephalothorax anterior, with epistome; C pleotelson and uropod; D antennule; E right cheliped; F left cheliped palm (mesial view); G pereopod-1; H pereopod-3; J pereopod- 4. Scale bars: (i) 1 mm for A; (ii) 0.125 mm for B–J.