Cyclopoapseudes (Exopoapseudes) plumosa, Błażewicz-Paszkowycz & Bamber, 2012

Błażewicz-Paszkowycz, M. & Bamber, R. N., 2012, The Shallow-water Tanaidacea (Arthropoda: Malacostraca: Peracarida) of the Bass Strait, Victoria, Australia (other than the Tanaidae), Memoirs of Museum Victoria 69, pp. 1-235 : 32-38

Cyclopoapseudes (Exopoapseudes) plumosa sp. nov.

Figures 22–25

Material examined. 1 (J60994), holotype, 1 (3.5 mm long) (J60993), allotype, 2 females with empty brood pouch (3 mm long), 1 brooding (3 mm long), 7, 8 subadult (1 dissected), 47 other specimens (J57560), paratypes, CPBS 33 S, Western Port off Crib Point, 38º22.06'S 145º14.10'E, 13 m depth, reef with sponges, 5 March 1965, coll. A.J. Gilmour.

Description of female with oostegites. Body ( Fig. 22A) compact, grossly similar to that of C. diceneon , holotype 3.7 mm long (tip of rostrum to posterior of pleotelson), 3.5 times as long as wide, narrower posteriorly. Cephalothorax subrectangular, wider than long (1.5 times as wide as long without rostrum), anterior margin with conspicuous rounded rostrum with smooth anterior margin. Eyes present on robust eyelobes; paired dorsal plumose setae, lateral plumose and simple setae as figured. Pereonites all with lateral margins expanded and uniformly convex, each with anterior row of 6 to 8 plumose setae, posterior pair of plumose setae, and numerous lateral marginal plumose and simple setae; pereonites 1 to 5 subequal in length (pereonite 1 just shortest), about 0.4 times as long as cephalothorax; pereonite 6 shortest, 0.6 times as long as pereonite 2 (all pereonites respectively 3.25, 3.0, 3.0, 2.6, 2.6 and 3.8 times as wide as long). Pleon three times as long as pereonite 2, of five free subequal pleonites bearing pleopods; pleonites dorsally with paired low posterior tubercles, about seven times as wide as long, with paired mid-dorsal plumose setae, laterally expanded by spiniform apophyses each bearing three or four plumose setae. Pleotelson distally with truncated protuberance, slightly longer than wide and half as long as whole pleon, with midlateral indentation; anterodorsal row of four plumose setae, postero-dorsal triad of plumose setae, laterally with seven marginal plumose setae.

Antennule ( Fig. 23A). Peduncle proximal article compact, twice as long as wide, inner margin with paired mesial and three subdistal plumose setae, outer margin with entire row of plumose setae; second article one-third as long as first, with inner and distal groups of plumose setae; third article two-thirds length of second, with outer distal seta and inner marginal plumose setae; fourth just shorter than third, with distal simple setae. Main flagellum of 7 segments, segments 2, 3 and 5 each bearing single aesthetasc; accessory flagellum of 4 segments.

Antenna ( Fig. 23B). Proximal peduncle article with inner distal pair of plumose setae; article 2 just longer than article 1, inner margin bearing pair of plumose setae and sub-proximal rounded apophysis, outer margin with three plumose setae and subdistal squama with seven simple marginal setae; peduncle article 3 shorter than wide, one-quarter the length of article 2, with one simple and one plumose inner setae; article 4 twice as long as article 3, with inner distal pairs of simple and penicillate setae; article 5 slightly longer than article 4, with inner and outer distal simple setae and paired inner penicillate setae. Flagellum of seven segments.

Labrum (not figured) rounded, distally finely setulose. Left mandible ( Fig. 23D) bearing strong, pointed and crenulated pars incisiva, lacinia mobilis slender with fine denticulations, setiferous lobe with one stout and five finer compound setae, pars molaris ( Fig. 23 D') robust, blunt, margin with row of rounded tubercles and fine teeth; mandibular palp of three articles, proximal article with single subdistal seta, article 2 more than half as long as whole palp with four simple distal setae, article 3 shorter than article 1 with four subdistal and two distal simple setae. Right mandible ( Fig. 23C) as left, but lacinia mobilis with more robust dentition, setiferous lobe with one simple and seven compound setae. Maxillule ( Fig. 23E) inner endite with five finely setulate distal setae, inner margin finely setulose; outer endite with nine distal spines and two subdistal setulose setae, outer margin finely setose, inner margin with fine rows of setules. Palp of two articles, distal article with distal row of five simple setae Maxilla ( Fig. 23F) with naked outer margin; outer lobe of moveable endite with two simple subdistal setae and eight simple distal setae; inner lobe of moveable endite with four simple and two setulose setae; outer lobe of inner endite with six outer simple setae interspersed with two bidenticulate spines, inner half with two bidenticulate spines and three distally compound spines; inner lobe of fixed endite with rostral row of 19 setae guarding five longer setulose setae. Labium ( Fig. 23G) with smooth outer margin, palp with fine lateral setules and two simple distal spines. Maxilliped ( Fig. 23H) basis with finely setose outer margin, no distal setae; palp article 1 with outer distal simple seta and inner distal finely setulose seta; palp article 2 longer than wide, inner margin with rows of numerous short setae, and two simple and two setulose longer setae in proximal half, outer margin finely denticulate with slender distal spine reaching tip of third article; palp article 3 with 10 simple setae along inner margin; palp article 4 with eleven setae along broad distal margin. Endite ( Fig. 23 H') with paired, slender, simple inner caudodistal setae, linguiform inner distal spines and simple outer distal setae, setulose outer margin, two coupling-hooks. Epignath ( Fig. 23I) slender, linguiform, with distally setulose distal spine.

Cheliped ( Fig. 24B) basis 2.8 times as long as wide, narrow proximally, with short dorsodistal simple setae and four longer ventrodistal setae; exopodite with four plumose setae. Merus subrectangular, with four distal simple setae. Carpus 2.5 times as long as wide, with row of long simple setae along ventral margin. Chela stout, palm just longer than wide and fixed finger 0.6 times as long as palm, ventral margin densely setose; slight setose apophysis between fixed finger and articulation of dactylus; cutting edge of fixed finger serrated, distal claw stout; dactylus with proximal tooth-like apophysis on cutting edge, distal claw pointed.

Pereopod 1 ( Fig. 25A) basis three times as long as wide, dorsal margin with five simple setae on a slightly convoluted margin, ventral margin with paired proximal plumose setae, two mid-ventral setae and four ventrodistal setae; exopodite present, 3-articled, article 3 with five distal plumose setae. Ischium with four simple ventrodistal setae. Merus just under half as long as basis, expanded distally, with numerous ventral simple setae, ventrodistal spine, and curved, slender dorsodistal spine with longer adjacent simple setae. Carpus 0.8 times as long as merus, with two ventral spines and intervening simple setae, and single dorsodistal spine amongst tuft of longer setae. Propodus slightly anaxial on carpus, longer than merus, with four ventral spines alternating with simple setae, one ventrodistal spine adjacent to dactylus, and five dorsal spines alternating with simple setae. Dactylus more than half as long as propodus, with mid-dorsal fine setae, ventrodistal seta; unguis mounted subdistally, short.

Pereopod 2 ( Fig. 25B) more slender but similar to pereopod 1. Coxa with plumose setae. Basis three times as long as wide with ventral and ventrodistal plumose setae. Merus 1.1 times as long as carpus, with ventrodistal spine but no dorsodistal spine. Propodus with four ventral and three dorsal spines with interspersed setae. Pereopod 3 ( Fig. 25C) similar to pereopod 2, but basis with longer and dorsal plumose seta, merus with two ventral spines, carpus with two dorsodistal spines, propodus with two dorsal spines.

Pereopod 4 ( Fig. 25D) basis 5 times as long as wide, naked other than three ventrodistal plumose setae; merus with two ventrodistal spines and inner-distal group of setae as long as carpus; carpus twice as long as merus, distally with slender, curved spines and simple setae; propodus as long as carpus, articulated anaxially on carpus, widening distally to square end, with dense group of finely denticulate shorter and longer setae; dactylus plus unguis as long as propodus. Pereopod 5 ( Fig. 25E) similar to pereopod 2, basis with ventral simple setae; merus shorter than carpus, with two ventrodistal spines; carpus with two ventrodistal and one dorsodistal spines; propodus with three ventral and two dorsodistal spines.

Pereopod 6 ( Fig. 25F) basis arrayed with proximal, dorsal subdistal, and ventral plumose setae as figured; ischium with four ventrodistal plumose setae; merus and carpus with plumose setae along dorsal and ventral margins, carpus with single dorsodistal spine; propodus with comb of fine leaf-like spines along distal half of ventral margin and around dactylus, dactylus with adjacent slender, curved spine.

Pleopods ( Fig. 25G) all alike. Basis with two dorsal plumose setae, ventral margin naked. Endopod shorter than exopod, linguiform, with nine ventral and distal plumose setae; exopod subovate, with seven plumose setae around distal margin.

Uropod ( Fig. 25H) biramous, exopod just shorter than pleotelson, of six segments, endopod 3.75 times as long as exopod, of fifteen segments.

Distinctions of male. Sexual dimorphism minimal ( Fig. 22B), cheliped ( Fig. 24A) more robust, dorsal margin of basis expanded and bearing row of 11 simple setae; merus narrow proximally, with two distal setae; carpus only 1.7 times as long as wide, with three mid-ventral setae; propodus as long as wide, with dorsal marginal rows of microtrichia, chela fingers as those of female but more robust.

Etymology. named for the plumose dorsal setae on the carapace.

Remarks. The morphology of the body of the present species is typical for the genus, as are the conformation of the mandible palp, and of the fourth pereopod, both being unusual features characteristic of the genus. As commented above, Cyclopoapseudes (Exopoapseudes) plumosa sp. nov. shares the possession of exopodites on the cheliped and pereopod 1 only with C. (E.) diceneon . It is distinguished from that species particularly in the form of the pleotelson, that of the present species being almost square in outline (although with mid-lateral indentation), that of C. (E.) diceneon narrowing at half its length to give a T-shape when viewed dorsally, with a conical posterior protuberance bearing long paired distal setae. In addition, C. (E.) plumosa has plumose setae dorsally on the carapace (that of C. (E.) diceneon being naked), a somewhat more slender and more setose antennule, more setose pereopods, inter alia.

Gardiner (1973) distinguished brooding females and subadult males (with a presumed male genital cone “anlage”), and only the latter had a cheliped with a stout propodus and a tooth-like apophysis on the cutting edge of the dactylus. The cheliped of the female figured here ( Fig. 24B) is even more robust than that of Gardiner’s male, but has an oostegite, contrary to Gardiner’s (ibid.) contention that all metapseudids are without an oostegites on the cheliped. The male cheliped of the present species also demonstrates sexual dimorphism. Menzies (1953) based C. indecorus on what he referred to as a male (without specifying why), and his relatively incomplete description shows a chela without tooth-like apophysis; with only one specimen, no sexual dimorphism is known for this species. Finally, Băcescu (1975) gave an even less complete description of C. estafricana , but based on a brooding female and a juvenile, so again no information is available on dimorphism or hermaphroditism. This genus unfortunately is generally of sparse occurrence.