Poorea gutui, Bird, 2019

Bird, Graham J., 2019, Tanaidacea (Crustacea: Peracarida) from the Southern French Polynesia Expedition, 2014. I. Tanaidomorpha, Zootaxa 4548 (1), pp. 1-75 : 26-28

Poorea gutui n. sp.

( Figs 11–15 )

Material examined. Holotype —non-ovigerous ♀, 2.6 mm, P. 102339, Stn 54-2, northern entrance to Ahurei Harbour , Rapa Iti, Austral Islands, 27° 36' 46" S 144° 20' 32" W, finely-branched coral, 1–5 m, 6 October 2014, coll. A. Reid, S.J. Keable, C. Sim-Smith, and C. Bedford.

Allotype —dimorphic ♂, 2.24 mm, P. 102333, Stn 54-5, coral rubble, other station details as for holotype.

Paratypes —AUSTRAL ISLANDS: one non-ov. ♀ P. 102340, three non-ov. ♀♀, one ov. ♀, three ♂♂ P.99213, Stn 6-6; one non-ov. ♀, one prep. ♀, one post-ov. ♀ P. 102338, Stn 8-8; one non-ov. ♀ P. 102337, Stn 16-7; seven non-ov. ♀♀, three ♂♂ MA73584, one ♂ P. 102342, one ♂ P.99216, Stn 54-2; one prep. ♀ dissected on two microslides P. 102332, P.102332.001, one manca-III (lost), three non-ov. ♀♀, one prep. ♀, one ov. ♀♀, one post-ov. ♀, eight cop. ♂♂ P. 102334, one cop. ♂ dissected on two microslides P.102335.001, one post-ov. ♀ chelipeds dissected on microslide P. 102336, P.102336.001, one non-ov. ♀, four ♂♂ P. 102341, Stn 54-5.

Diagnosis. Female. Cephalothorax as long as pereonites 1–3 combined. Pereonite-1 shorter than pereonites 2– 3. Antenna article-3 without ventrodistal seta or spine. Maxilliped bases with three setae; endites with three flat tubercles. Cheliped merus with three setae; propodus with six distal setae. Pereopod-1 dactylus and unguis together longer than propodus. Pereopods 2–3 ischium with one seta; merus with inferodistal crotchet; propodus with two distal setae. Pereopods 4–6 ischium with two setae. Uropod endopod four-segmented (mature individuals), exopod half length of segment-1 of endopod.

Male. Most of above and: antennule about length of cephalothorax; article-1 about length of articles 2–3 combined; flagellum four-segmented. Cheliped basis anterior mass with mesial distodorsal apophysis; merus longer than ventral margin of carpus; palm with vertical spine comb; fixed finger with triangular (cf., ‘square’ sensu Edgar 2012 ) proximal apophysis on incisive margin.

Etymology. For Professor Modest Guţu, of the Muséum National d’Histoire Naturelle “Grigore Antipa”, for his many contributions to tanaidacean systematics and recent work on the complex family Leptocheliidae .

Description. Holotype non-ovigerous female, 2.6 mm (P. 102339). Habitus ( Fig. 11A ) slender, 7.6 times ltb. Cephalothorax 1.5 times ltb, just longer than pereonites 1–2 combined; carapace entire, lateral margins with seta just posterior to eye-lobe (but cheliped sclerite and basis setae also visible in dorsal view); rostrum pointed, weakly produced; eyes conical, multifaceted, with dark pigment. Pereon with weakly convex margins of pereonites 1–6, all shorter than broad, 0.5, 0.8, 0.8, 0.8, 0.9, and 0.7 times ltb respectively, pereonite-6 slightly wider posteriorly, all with pair of anterolateral setae (coxal setae visible in dorsal view on pereonites 1–3). Pleon 16% of body length, just longer than broad, epimera 1–5 ( Fig. 11B ) with two setae. Pleotelson ( Fig. 11A, C–D ) length of pleonite-5 and half of pleonite-4 together ( Fig. 11D for true length), rounded with weakly produced posterior margin, and deflexed apex bearing two long setae; other setation as figured.

Paratype non-ovigerous female, 2.4 mm (P. 102332, P.102332.001). Antennule ( Fig. 11E ) 0.8 times length of cephalothorax, 4.5 ltb; article-1 0.6 times total length, 2.7 times ltb, lateral margin with three proximal PSS, one long seta with associated PSS at midlength, and distal seta with associated PSS longer than article-2, mesial margin with seta; article-2 twice length of broad, with three distal setae, longest 0.6 times length of article; article-3 length of article-2, with distal seta and one PSS; cap-like segment with four setae and an aesthetasc. Antenna ( Fig. 11F ) 0.75 times length of antennule; article-1 with ventrodistal seta; article-2 just longer than broad, with slender dorso- and ventrodistal thorn-like spines, ventral spine appearing fused with article; article-3 0.8 times length of article-2, with dorsodistal thorn-like spine and subdistal spinule; article-4 2.8 times ltb, length of articles 2 and 3 combined, with 2 or 3 sub-distal PSS and three simple distal setae (two longer than article-5); article-5 length of article-3, with two unequal setae and one PSS; article-6 with five setae .

Mouthparts. Labrum ( Fig. 12A ) typical, hood-shaped, setulate. Mandibles ( Fig. 12B–C ) typical; left mandible ( Fig. 12B ) incisor crenulate, lacinia broad and distally crenulate, molar with spinose-ridged and granulose apex; incisor of right mandible ( Fig. 12C ) weakly bifid, with crenulate distal margin, molar as in left mandible. Labium ( Fig. 12D ) typical, outer lobes broader but not as long as inner, both distally setulate. Maxillule ( Fig. 12E ) endite setulate on distal part, with at least eleven crowded terminal spines and outer corona of finer setae and setules; palp with two setae. Maxilla not observed.

Maxilliped ( Fig. 12F–G ) combined bases 0.9 times ltb, basis with three long setae, overreaching endite (mature individuals). Endite distal margin with large blunt lateral seta, one blunt (medial) and two acuminate tubercles, and with two medial coupling hooks. Palp article-2 with lateral seta and four unequal mesial setae, mesial margin finely setulate, article-3 with about eight setae (in two rows); article-4 with superodistal seta and about ten apical setae. Epignath not observed.

Cheliped ( Fig. 12H–J ) coxal sclerite triangular, reaching posterior of cephalothorax, with seta (visible in dorsal view); basis posterior lobe reaching pereonite-1, half length of anterior mass, latter with dorsolateral seta; merus with three dispersed ventral setae; carpus 1.9 times ltb, with two dorsal setae and three ventral setae. Chela just shorter and narrower than carpus; propodus 2.3 times ltb, palm typically sub-parallel, with slender spine near articulation with dactylus on strongly convex margin, and ( Fig. 12J ) two mesial combs of four spines and about nine setules respectively; fixed finger 0.45 times length of palm, with three ventral/mesial setae and three near incisive margin, incisive margin raised, undulate; dactylus with proximomesial spine, incisive margin distally crenate.

Pereopod-1 ( Fig.13A ) coxa (not figured) with seta (and oostegite bud in preparatory female); basis arcuate, 3.8 times ltb, with proximal superior seta and PSS; ischium with seta; merus just longer than distal breadth, distal margin oblique with carpus, with inferodistal seta; carpus 1.2 times longer than merus, with three superodistal setae and one inferodistal seta; propodus just longer than merus and carpus combined, 3.3 times ltb, with three unequal superodistal setae, and one inferodistal seta; dactylus 1.1 times longer than unguis, with proximal accessory seta; unguis with distal pore, together with dactylus just longer than propodus.

Pereopod-2 ( Fig. 13B ) coxa with seta (and oostegite bud in preparatory female); basis broader than in pereopod-1, 2.6 times ltb, with proximal superior seta and two PSS; ischium with seta; merus length of broad, with inferodistal crotchet and inferior spinules; carpus just longer than merus, 1.1 times longer than broad, with superodistal seta, two short inferodistal crotchets (mesial weaker and more acuminate) and one seta, inferior margin spinulate; propodus 2.5 times ltb, length of merus and carpus combined, with two distal setae and one inferodistal spine; dactylus with accessory seta, length of unguis, together claw-like and 0.6 times length of propodus.

Pereopod-3 ( Fig.13C ) like pereopod-2 but slightly shorter overall.

Pereopod-4 ( Fig. 13D ) coxa without seta (and with oostegite bud in preparatory female, as figured); basis broader than in pereopods 2–3, 2.2 times as ltb, with superior groove and proximal superior PSS; ischium heavily shielded by basis, with two setae; merus geniculate, about twice length of broad, with two stout inferodistal crotchets; carpus about length of merus, subrectangular with three distal crotchets and one superodistal seta; propodus 1.2 times longer than carpus, superior margin with rows of microtrichia, with one blade-like and two slender superodistal spines, and two inferodistal spines; dactylus and unguis claw-like, 0.7 times length of propodus, dactylus with distal setule.

Pereopod-5 ( Fig. 13E ) as pereopod-4.

Pereopod-6 ( Fig. 13F ) like pereopod-5 but propodus with five slender distal spines, one longer than rest.

Pleopod ( Fig. 13G–H ) peduncle just shorter than broad, mesial margin with plumose seta; rami subequal, subovate, endopod and exopod about 2.1–2.3 times ltb respectively; endopod mesial margin with plumose seta at mid- length, lateral margin with fringe of 10–11 plumose setae, distalmost with whip-like tip; exopod lateral margin with proximal plumose seta separated by small gap from fringe of 17 plumose setae.

Uropod ( Fig. 11G ) peduncle longer than broad, naked; endopod four- segmented, with one or two simple setae on sub-terminal segments, segment-3 with two PSS, segment-4 with five simple setae and a PSS; exopod onesegmented, half length of segment-1 of endopod, with three distal setae.

Intraspecific variation. Non-ovigerous, preparatory, ovigerous, and post-ovigerous females. Body length 1.3– 3.0 mm, of which non-ovigerous females 1.0– 2.8 mm (n=19), preparatory females 2.1–2.5 mm (n=3), ovigerous females 1.9–2.9 mm (n=3), and post-ovigerous females 2.6–3.0 mm (n=3).

Manca-III. Habitus like small non-ovigerous female but with rudimentary pereopods-6 and pleopods; length 0.9 mm (n=1). Uropod endopod three-segmented.

Allotype copulatory male, 2.2 mm (P. 102333). Habitus ( Fig. 14A ) fairly slender, 6.1 times ltb. Cephalothorax 1.3 times ltb, rostrum slightly produced, carapace with two setae posterior to each eyelobe, and basis and sclerite setae visible from above. Pereonites all shorter than broad, pereonite-1 shortest, pereonites 2–3 1.3 times longer than pereonite-1, subequal, and pereonites 4–5 longer and subequal; setation as figured. Pleon 19% of body length, length of broad, epimera each with two or three setae. Pleotelson as in female.

Paratype copulatory male, 2.5 mm (P.102335.001). Antennule ( Fig. 14B ) just longer than cephalothorax; peduncle three-articled, article-1 2.3 times ltb; article-2 1.7 times ltb; article-3 0.6 times length of article-2, simple; flagellum four-segmented, last segment much smaller than preceding segments, all except terminal with bundle of aesthetascs, segment-1 with two bundles; other setation as figured. Antenna ( Fig. 14C ) like that in female but spines of articles 2–3 weaker; article-5 longer and thinner.

Mouthparts atrophied, fused solid mass.

Maxilliped ( Fig. 14D–E ) present but reduced, bases with three distal setae, endites minute and distally crenulate, palp one-articled.

Cheliped ( Fig. 14F–H ) stout form; triangular sclerite with seta; basis posterior lobe smaller than anterior mass, with dorsolateral seta and distomesial condyle; merus with proximomesial seta and three inferior setae; carpus 1.4 times ltb; propodus longer but narrower than carpus, 1.9 times ltb, palm 1.6 times longer than fixed finger, mesial comb ( Fig. 14H ) with 14 simple spines; fixed finger with two triangular apophyses on incisive margin; dactylus with row of peg-like spines; other setation as figured.

Pereopod-1 ( Fig. 15A ) like that of female but basis more slender, 4.9 times ltb and with two superior PSS; merus with more oblique articulation with carpus and with two inferior setae. Pereopod-2 ( Fig. 15B ) like that of female but basis slightly more elongate, 3.2 times ltb; merus with inferior seta. Pereopod-3 ( Fig. 15C ) like pereopod-2 but smaller, 0.9 times as long overall.

Pereopod-4 ( Fig. 15D ) like that of female, but basis slightly stouter, twice length of broad, with two superior PSS; propodus and claw combined proportionately longer, propodus with three slender superodistal spines. Pereopod-5 ( Fig. 15E ) like pereopod-4 but basis slightly (1.1 times) longer. Pereopod-6 ( Fig. 15F ) like pereopods 4–5 but basis slightly more slender, 2.5 times ltb; propodus with one long superodistal seta and five blade-like spines.

Pleopod ( Fig. 15G ) like that of female but with one or two additional setae on distal fringe of exopod and endopod; exopod more slender, three times ltb.

Uropod ( Fig. 15H ) like female, but peduncle with four distal setae, one terminal seta much longer than rest.

Body length of other copulatory males 1.4–2.5 mm (n=14).

Distribution and habitat. Ahurei Harbour and Pariati Bay, Rapa Iti, Austral Islands, 1–22 m, from coral rubble and finely branched coral.

Remarks. Males of Poorea are known for five of the seven species, and females also for five, with only three having descriptions of both sexes: P. karragarrus ( Bamber, 2008) , P. nobbi , and P. vatulelensis ( Guţu & Iliffe, 2011) . Poorea gutui n. sp. has a unique combination of characters useful for diagnosis although it shares some with other species, such as the dentition of the male’s cheliped fixed finger with P. wrighti . It differs from P. vatulelensis from Vatulele ( Fiji) and Ouvéa (Loyalty Islands) in having, in the female, three maxilliped basis setae (cf. three or four), six distal setae on the cheliped fixed finger (cf. seven), an inferodistal seta rather than a spine on the merus of pereopods 2–3, and a shorter uropod exopod. Poorea gutui is also one of the most slender species, with the lowest cephalothorax: pereonites 1–3 length ratio. With the male, apart from P. gutui having fewer flagellar segments in the antennule (four rather than six), the differences are largely in the cheliped—a comparison of salient characters distributed in all the Poorea species is shown in Table 7.

Figures

FIGURE 11. Poorea gutui n. sp. non-ovigerous female holotype (P.102339). A, habitus; B epimeral setation; C, pleotelson, dorsal (downcurved); D, pleotelson, lateral. Non-ovigerous female paratype (P.102332, P.102332.001). E, antennule; F, antenna; G, uropod. Scale bars: habitus 1 mm, others 0.1 mm.

FIGURE 12. Poorea gutui non-ovigerous female paratype (P.102332, P.102332.001). A, labrum; B–C, left and right mandibles respectively; D, labium; E, maxillule; F, maxilliped, palps omitted; G, palp. Non-ovigerous female paratype (P.102336, P.102336.001). H, right cheliped; I, fixed finger, distal; J, left chela mesial comb and dactylus. Scale bars: 0.1 mm.

FIGURE 13. Poorea gutui non-ovigerous female paratype (P.102332, P.102332.001). A–F, pereopods 1–6 respectively; G, pleopod; H, pleopod endopod. Scale bars: 0.1 mm.

FIGURE 14. Poorea gutui male allotype (P.102333). A, habitus. Male paratype (P.102335.001). B, antennule; C, antenna; D, maxilliped; E, maxilliped endites (?); F, right cheliped; G, detail of cheliped basis condyle; H, left chela. Scale bars: habitus 1 mm, others 0.1 mm.

FIGURE 15. Poorea gutui male paratype (P.102335.001). A–F, pereopods 1–6 respectively, D–F with details of obscured spines; G, pleopod; H, uropod. Scale bars: 0.1 mm.