Paradoxapseudes bassoprofundo, Bamber & Błażewicz-Paszkowycz, 2013

Bamber, Roger N. & Błażewicz-Paszkowycz, Magdalena, 2013, Another inordinate fondness: diversity of the tanaidacean fauna of Australia, with description of three new taxa, Journal of Natural History (J. Nat. Hist.) 47 (25 - 28), pp. 1767-1789 : 1769-1776

Paradoxapseudes bassoprofundo sp. nov.

( Figures 1–4 )

Type material

Holotype. 1 ♀ ( MV J58575 ), Stn. SLOPE 40 , South of Point Hicks , Victoria, 38 ◦ 17.70 ′ S, 149 ◦ 11.30 ′ E, 400 m depth, coarse sand, gravel, mud, many sponges, 24 July 1986, WHOI Epibenthic sled, coll. M. Gomon et al.; RV Franklin.

Allotype. 1 ♂ ( MV J58576 ), same data as holotype.

Paratypes. 10 ♂♂, 24 ♀♀ (mostly brooding or with oostegites; 2 dissected) ( MV J57910 ), same data as holotype . 21 specimens ( MV J57929 ), Stn. SLOPE 22 , off Eden , New South Wales, 37 ◦ 00.60 ′ S, 150 ◦ 20.70 ′ E, 363 m depth, 21 July 1986, WHOI Epibenthic sled, coll. G. Poore et al . 1 specimen ( MV J57914 ), Stn. SLOPE 1 , off Nowra , New South Wales, 34 ◦ 59.31 ′ S, 151 ◦ 05.56 ′ E, 204 m depth, 14 July 1986, WHOI Epibenthic sled, coll. G. Poore et al . 1 specimen ( MV J57934 ), Stn. SLOPE 47 , off Freycinet Peninsula , Tasmania, 41 ◦ 58.43 ′ S, 148 ◦ 38.80 ′ E, 500–600 m depth, coarse shell, 27 July 1986, WHOI Epibenthic sled, coll. M. Gomon et al.; RV Franklin . 32 specimens ( MV J57919 ), Stn. SLOPE 21 , off Eden , New South Wales, 36 ◦ 57.40 ′ S, 150 ◦ 18.80 ′ E, 220 m depth, 20 July 1986, WHOI Epibenthic sled, coll. G. Poore et al .

Description of female

Body ( Figure 1A,B ) dorsoventrally flattened, holotype 4.1 mm long, seven times as long as wide, tapering towards posterior. Cephalothorax subrectangular, 1.3 times as long as wide, with large triangular rostrum; eyelobes and eyes present. Pereonites midlaterally indented, pereonites 3 to 6 with stout angular anterolateral corners; pereonite 1 shortest, 0.3 times as long as cephalothorax; pereonite 2 just longer than pereonite 1; pereonites 3 and 5 subequal in length, 1.6 times as long as pereonite 1, pereonite 6 shorter, 1.25 times as long as pereonite 1 (all pereonites respectively 2.5, 2.1, 1.5, 1.3, 1.3 and 1.6 times as wide as long). Pleon narrower than pereon, 1.3 times as long as cephalothorax, tapering posteriorly, with five free subequal pleonites bearing pleopods; each pleonite about three times as wide as long and extended posterolaterally into sharp, triangular apophysis. Elongate pleotelson subpentangular, as long as last four pleonites together, three times as long as wide.

Antennule ( Figure 2A ) proximal peduncle article four times as long as wide, margins with penicillate setae largely in proximal half and simple setae largely in distal half, inner margin with no proximal corrugation; second peduncle article 2.5 times as long as wide, 0.4 times as long as first, with inner and outer simple distal setae; third article half length of second, about twice as long as wide; fourth peduncle article half as long as third. Main flagellum of seven segments, single aesthetasc present on each of fifth and seventh segments; accessory flagellum of three segments.

Antenna ( Figure 2B ), proximal peduncle article with inner apophysis bearing small seta and two teeth. Second peduncle article twice as long as first, twice as long as wide, margins sinuous with mid-inner setae adjacent to pointed apophysis, with elongate linguiform squama bearing six marginal setae. Third peduncle article just shorter than wide and one-fifth as long as second; fourth article 0.7 times as long as second, fifth article as long as fourth. Flagellum of five segments.

Labrum ( Figure 2C ) rounded, simple, distally crenulate; epistome conspicuous. Right mandible ( Figure 2D ) with tricuspidate pars incisiva, outer margin roughly denticulate, setiferous lobe with five compound setae and one simple seta; palp ( Figure 2 D′ ) of three articles, proximal article shortest with four simple setae, second article longest with two medial simple setae, third article with nine inner setae of various sizes in distal half and one subdistal outer seta. Left mandible (not figured) similar but with crenulate lacinia mobilis. Labium ( Figure 2G ) with setulose outer and distal margins, palp with fine lateral setules and three simple distal setae. Maxillule ( Figure 2E ) inner endite with slight outer apophysis, finely setose outer margin and four setulose distal setae, outer endite with eleven distal spines and two subdistal setae, outer margin finely setose, palp of two articles, distally with three setae each with setulose tip. Maxilla ( Figure 2F ) outer lobe of moveable endite with two simple subdistal sickle-like setae and four distal setulose setae, inner lobe with five slender curved setae and five stouter setae; outer lobe of fixed endite with three simple and five compound distal spines and subdistal biserrate spine, inner lobe with four stout, proximally setulose setae and rostral row of 15 setae. Maxilliped ( Figure 2H ) basis naked but with two rounded outer tubercles; first palp article with one very long inner seta and smaller outer seta; second palp article longer than wide, with four submarginal and about 16 marginal inner setae, and outer distal spine; third palp article nearly twice as long as wide, with inner group of seven simple curved setae; fourth palp article with seven distal simple setae; endites ( Figure 2 H′ ) with two coupling hooks, outer margin densely setulose, distally with single inner and outer simple seta and numerous slender, blunt, bifurcate spines, one longer proximally setulose subdistal seta. Epignath ( Figure 2I ) oval, with setose inner lobe and setose distal spine.

Cheliped ( Figure 3A ) basis twice as long as wide, ventrally with two proximal, one central and paired distal simple setae, dorsally with two fine distal setae; threearticled exopodite present, slender, distal article with four plumose setae. Merus with two simple setae on ventrodistal “shoulder”; carpus three times as long as wide, with five ventral marginal plumose setae. Chela stout, fixed finger as long as palm with five ventral setae, cutting edge setose and with proximal tooth-like apophysis, tuft of four setae proximal to apophysis; dactylus and claw not overreaching fixed finger, with three outer setae and fine setules on cutting edge.

Pereopod 1 ( Figure 4A ) with conspicuous setose apophysis on coxa; basis 4.3 times as long as wide, dorsal margin bearing one longer and three shorter simple setae in proximal half, ventral margin with single proximal, single mid-ventral and paired distal simple setae; exopodite ( Figure 4 A′ ) three-articled, distal article with six plumose setae. Ischium with one simple ventrodistal seta. Merus half as long as basis, widening distally, with single dorsodistal and ventrodistal spines, ventroproximal and ventrodistal groups each of three simple setae. Carpus as long as merus, with one dorsodistal and two ventral spines, setose margins including dorsodistal setae exceeding tip of propodus. Propodus 0.8 times as long as carpus, with two dorsodistal and four ventral spines interspersed with single fine setae, short simple distal spine adjacent to dactylus attachment. Dactylus slender, with two ventral denticulations, unguis short, both together 0.9 times as long as propodus.

Pereopod 2 ( Figure 4B ) basis 5.5 times as long as wide with three ventrodistal setae not reaching to half length of merus; ischium as long as wide, with four ventral setae; merus shorter than carpus, with four ventral and two dorsodistal setae; carpus with single slender ventrodistal and dorsodistal spines, and few adjacent simple setae; propodus just longer than carpus, with five ventral and four dorsodistal setae; dactylus with dorsal seta, dactylus and unguis slender, curved, subequal in length, together as long as propodus. Pereopod 3 ( Figure 4C ) similar to pereopod 2 but basis with ventroproximal seta, ischium with two setae.

Pereopod 4 ( Figure 4D ) similar to pereopod 3 but with stouter basis 4.7 times as long as wide, with three dorsoproximal setae and one ventro-subdistal penicillate seta; carpus 2.7 times as long as merus, with distal setae forming crown; propodus shorter than carpus, with dorsoproximal penicillate seta and distal tuft of about 12 shorter setae; dactylus longer than unguis, both together shorter than propodus.

Pereopod 5 ( Figure 4E ) similar to pereopod 4, but basis without penicillate setae, carpus more sparsely setose; propodus with ventral comb of 11 leaf-like spines in distal half. Pereopod 6 ( Figure 4F ) similar to pereopod 5, but basis with five plumose dorsal setae, and proximally with one dorsal penicillate seta and one ventral simple seta; merus with two dorsal plumose setae; carpus with two dorsal plumose setae; propodus with two dorsal penicillate setae and combs of small leaf-like spines ventrally and distally; dactylus plus unguis slender, curved, together as long as propodus.

Pleopods typical for genus ( Figure 4G ), basis with one inner but no outer plumose setae, endopod with seven plumose marginal setae, exopod shorter with six plumose marginal setae.

Uropod ( Figure 4H ) biramous, basis with five distal simple setae; exopod more than twice as long as basis and of five segments; endopod elongate, filiform, with about 17 segments.

Dimorphism of male ( Figure 1C )

Generally similar to female, slightly smaller (body length 3.5 mm); dimorphism shown by antennules and antennae being proportionately longer, and by cheliped ( Figure 3B ). Cheliped basis with mid-dorsal spine; carpus with large, rounded ventral expansion, doubling width of article; chela as that of female but substantially larger, proximal apophysis on fixed finger more pronounced.

Etymology

A concatenation of “basso” from the Bass Strait, and “profundo” from the Latin profundus – deep, this being the deepest-occurring species of Paradoxapseudes yet discovered (noun in apposition).

Remarks

Paradoxapseudes bassoprofundo sp. nov. is the only described species of the genus to have a combination of no plumose setae on the basis of pereopod 1 nor proximal serration on the antennal peduncle, and with three maxillule palp setae. It is also larger than other described species, most of which are around 2.5 to 3 mm in body length.

Of the other three species with three maxillule palp setae, Paradoxapseudes bermudeus Băcescu 1980 , recorded from a marine cave in Bermuda, also has a prominent epistome as does the present species, but it has one fewer segment in the antennal flagellum, one fewer ventral spine on the propodus of pereopod 1, one more dorsal plumose seta on the basis of pereopod 6, 15 setae on the second article of the mandibular palp (compared with only two in P. bassoprofundo ), no pleopod basis setae, and antennular peduncle serration. Paradoxapseudes basibidens Guţu, 2007 , from the coast of Tanzania, has one fewer ventral spines on the propodus of pereopod 1, one fewer dorsal plumose setae on the basis of pereopod 6, six setae on the second article of the mandibular palp, two pleopod basis setae (compared with only one in P. bassoprofundo ), and plumose setae on the basis of pereopod 1. Paradoxapseudes larakia (Edgar, 1997) , also from Australia, has one fewer segment in the accessory flagellum of the antennule, one more dorsal plumose seta on the basis of pereopod 6, six setae on the second article of the mandibular palp, no pleopod basis setae, as well as plumose setae on the basis of pereopod 1 and antennular peduncle serration. The two shallow-water (<95 m) species from the Bass Strait ( Błażewicz-Paszkowycz and Bamber, 2012) differ from P. bassoprofundo in their mandibular palp setation, their shorter uropod exopods, in the conformation of the female cheliped and the antennae, and in the setation and spination of pereopod 1 (inter alia).

Of the eight putative species currently assigned to this genus in which males have been recorded, none of those males has the ventral expansion of the cheliped carpus shown by P. bassoprofundo .

Paradoxapseudes bassoprofundo was collected from the slope off southeastern Australia (Tasmania and New South Wales), at 204 to 600 m depth .

Figures

Figure 1. Paradoxapseudes bassoprofundo sp. nov. (A) Female holotype (MV J58575) dorsal; (B) female holotype lateral; (C) male (MV J58576), lateral. Scale bars 1.0 mm.

Figure 2. Paradoxapseudes bassoprofundo sp. nov. (A) antennule; (B) antenna; (C) labrum; (D) right mandible, with (D′), distal two articles of palp; (E) maxillule, with (E′), palp; (F) maxilla; (G) labium; (H) maxilliped, with (H′), endite; (I) epignath. Scale bars 0.1 mm.

Figure 3. Paradoxapseudes bassoprofundo sp. nov. Chelipeds of (A) female; (B) male. Scale bars 0.1 mm.

Figure 4. Paradoxapseudes bassoprofundo sp. nov. (A–F) Pereopods 1 to 6 respectively; (A′) exopodite of pereopod 1; (G) pleopod; (H) uropod. Scale bars 0.1 mm.