Araphuroides sala, 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 : 152-157

Araphuroides sala sp. nov.

Figures 102–104

Material examined. 1 (J58841), holotype, Western Port , off Crib Point, Stn CPBS-N 52 /272, 38º19.92'S 145º13.95'E, 19 m depth, sand and gravel, 31 March 1965; coll. A.J. Gilmour. 1 (J58843), paratype, Western Port , off Crib Point, Stn CPBS-N 25 /1, 38º20.25'S 145º14.68'E, 11 m depth, sand, 10 March 1965; coll. A.J. Gilmour. 1 (J58839), Stn CPBS-N 32 /1, 1 (J58840), Stn CPBS-N 32 /2, and 4 (J58842), Stn CPBS-N 32 /3 , paratypes, all Western Port , off Crib Point, 38º20.83'S 145º13.48'E, 13 m depth, sandy gravel, 23 March 1965; coll. A.J. Gilmour. 2 (J58534, J58535), paratypes, Eastern Bass Strait , 63 km E of North Point, Flinders Island, Stn BSS 167 , 39º44.8'S 148º40.6'E, 124 m depth, muddy sand, 14 November 1981 , coll. R.S. Wilson .

Description of female. Body ( Fig. 102A, B) slender, holotype 1.4 mm long, 8.1 times as long as wide. Cephalothorax pear-shaped, widest centrally, with distinct rounded rostrum, 1.6 times as long as wide, 2.7 times as long as pereonite 1, naked, eyes absent. Pereonites all naked, lateral margins convex; pereonite 1 short, 0.4 times as long as cephalothorax; pereonites 2 to 5 subequal, 1.25 times as long as pereonite 1; pereonite 6 shortest, 0.8 times as long as pereonite 1 (all pereonites respectively 1.5, 1.25, 1.25, 1.5, 1.3 and 2.0 times as wide as long). Pleon of five free subequal pleonites bearing pleopods plus pleotelson; each pleonite 4.4 times as wide as long, with single lateral epimeral seta on each side. Pleotelson subpentangular, 0.4 times as long as whole pleon, as long as wide, paired laterodistal setae either side of rounded mid-distal margin.

Antennule ( Fig. 103A) of four articles, proximal article 3.6 times as long as wide, longer than distal three articles together, distally with two tufts of penicillate setae and single outer simple seta; second article longer than wide, 0.4 times as long as first article, with four inner distal penicillate setae and one outer simple seta; third article compact, half as long as second article, with two simple distal setae; fourth article tapering, 1.4 times as long as third article, with six simple and one penicillate distal setae.

Antenna ( Fig. 103B) of six articles, proximal article compact, shorter than wide, fused to cephalothorax; second article as long as wide, with two distal setae; third article shorter than wide, 0.7 times as long as second article, with dorsodistal seta; fourth article longest, five times as long as wide, more than three times as long as second article, with penicillate seta in proximal half, crown of one simple and five penicillate distal setae and dorsal rows of microtrichia; fifth article as long as second, with one distal simple seta; sixth article minute with four distal setae.

Labrum ( Fig. 103C) rounded, hood-shaped, distally setose. Left mandible ( Fig. 103D) with wide, spade-like crenulate pars incisiva and triangular, crenulate lacinia mobilis, right mandible ( Fig. 103E) with crenulate and distally bifid pars incisiva and without lacinia mobilis; pars molaris of both mandibles stout, with fine, elongate distal denticulations. Labium ( Fig. 103H) simple, outer distal corner of both lobes setulose. Maxillule ( Fig. 103F) with nine finely-denticulate distal spines and few distal setules, palp with two distal setae. Maxilla ( Fig. 103G) simple, triangular, naked. Maxilliped ( Fig. 103I) palp first article naked, second article with one outer and three distal inner setae, two of these finely denticulate; third article with two longer mesial and two shorter distal inner setae, one of each of these finely denticulate; fourth article with four longer and one shorter distal finely-denticulate setae and one small subdistal outer seta; basis naked; endites distally each with two rounded tubercles, with outer-distal microtrichia and inner seta. Epignath ( Fig. 103J) slender, ribbon-like, distally pointed, naked.

Cheliped ( Fig. 103K) with rounded, naked basis 2.3 times as long as wide, merus subtriangular with single ventral seta, and covering about half of ventral margin of carpus; carpus 1.5 times as long as wide, with one longer and one much shorter midventral setae, one dorsodistal seta and one dorsoproximal seta, dorsal margin smooth; propodus just longer than wide, with two ventral setae, dorsally with two rows of rounded tubercles in distal half, outer face with row of rounded tubercles along ventral margin of fixed finger, inner comb-row of four setae; fixed finger with three setae below cutting edge and two or three small tooth-like apophyses on cutting edge; dactylus with rounded tubercles along dorsal margin.

Pereopod 1 ( Fig. 104A) not longer than others, coxa without apophysis, with seta; basis 2.9 times as long as wide, with dorsoproximal penicillate seta; ischium compact, with one ventrodistal seta almost as long as merus; merus 1.2 times as long as carpus, ventrodistally with seta and longer distally-denticulate spine just exceeding half length of carpus; carpus distally with shorter ventral spine and single distally-denticulate dorsodistal spines anteriorly and posteriorly; propodus 1.25 times as long as carpus, with ventrodistal spine and dorsodistal and ventral microtrichia; dactylus naked, unguis 1.5 times as long as dactylus, both together 1.4 times as long as propodus. Pereopod 2 ( Fig. 104B), similar to pereopod 1, basis with two dorsoproximal penicillate setae; merus and carpus subequal in length; propodus 1.5 times as long as carpus; dactylus and unguis together 1.2 times as long as propodus. Pereopod 3 ( Fig. 104C) similar to pereopod 2.

Pereopod 4 ( Fig. 104D) not more compact, coxa naked, basis three times as long as wide, with two dorsoproximal and two midventral penicillate setae; ischium with one shorter and one longer ventrodistal setae, latter as long as merus; merus just shorter than carpus, with two finely-denticulate ventrodistal spines; carpus with single dorsodistal and ventrodistal setae and three finely-denticulate ventrodistal spines, distally with microtrichia; propodus 1.2 times as long as carpus, with ventral fields of microtrichia, dorsal penicillate seta, two ventrodistal and one dorsodistal finely-denticulate spines; dactylus 0.8 times as long as unguis, both with fields of microtrichia, dactylus and unguis not fused into a claw, the two together 1.1 times as long as propodus. Pereopod 5 ( Fig. 104E) as pereopod 4, but basis without penicillate setae. Pereopod 6 ( Fig. 104F) as pereopod 5, but propodus with two ventral and three dorsal distal spines.

Pleopods ( Fig. 104G) all alike, with naked basis, endopod with subdistal inner plumose seta, exopod without setae on inner margin, outer margins with respectively 5 and 12 plumose setae, additional proximal exopod seta separated from others.

Uropod ( Fig. 104H, H') half as long as pleotelson, basis naked, exopod process half as long as endopod, with three distal setae; endopod of one segment, setose as figured.

Male. Unknown.

Etymology. Named after the English journalist George Augustus Henry Sala who, during a visit to Victoria in 1885, coined the phrase “Marvellous Melbourne”, which stuck long into the twentieth century and is apparently still used today by Melburnians (noun in apposition).

Remarks. Within the genus Araphuroides , only the three species described herein and A. bombus Larsen, 2005 are without a pseudo-articulation line on the fourth antennal article, and only the present species and A. batmania have rounded tubercles on the chela; these two also share the elongate setae on the ischia of the pereopods. A. batmania differs from A. sala sp. nov. in being without the dorsodistal tubercles on the chela, as well as in having only rounded distal tubercles on the mandibular molar process, and in having a uropod with a longer exopod process and a two-segmented endopod.

Araphuroides sala was found in Western Port and off Flinders Island in coarse to muddy sands at depths between 11 and 124 m.

Discussion of the genera Araphura and Araphuroides .

Sieg (1986a) originally distinguished Araphuroides from Araphura by their “body shape”, the pereonites of Araphura having parallel margins while those of the two species he attributed to Araphuroides (see above) having “gently rounded” margins; additionally, pereonite 2 in Araphura is “normally” as long as wide or slightly wider than long, while it is “distinctly broader than long” in Araphuroides ; further, he maintained that the merus on pereopod 1 is short, “only slightly longer than broad”, in Araphura , but “distinctly longer than broad” in Araphuroides . Finally, the pars molaris of the mandible is broad, with “at least one longer and several small toothlike processes” in Araphuroides , but is pointed “ending in three or four tiny tips” in Araphura .

Sieg & Dojiri (1989) expanded on these distinctions, citing pereonite 2 as being “at least as long as broad, but mostly longer than broad” in Araphura ; strangely, these authors showed the features of the ratio of length to width of pereonite 2, and of parallel- or convex-sided pereonites to be ontogenically variable. Larsen (2005) and Larsen et al. (2009) added the body length to width proportions as distinguishing these two genera ( Araphura 9 to 13 times as long as wide, Araphuroides less than nine times), even though this feature was not cited by Sieg (locc. cit.).

These various features for the Australian species of these two genera are shown in Table 2. None of the species has a pereopod 1 merus “only slightly longer than broad”. Other than this, it is apparent that the only species agreeing wholly with Sieg’s concept of Araphura is A. pygmothymus , and it is the only one with a “pointed” mandibular molar process. Yet, from their remaining morphology, A. yarra is clearly a species close to A. pygmothymus . Indeed, a number of these species appear to be siblings. Considering Larsen’s (2005) concept of body length to width, these Australian species show a gradation suggesting that any such distinction is entirely arbitrary.

Indeed, it is apparent that the “characters” diagnosing these genera according to Sieg (locc. cit.) are not consistent, and consideration of the features shown in table 2 as being diagnostic is to fall into the error or classifying characters rather than animals. To quote Linnaeus, “Characters come from the genus, not the genus from the characters. Characters are not there so that there should be a genus but in order that the genus should be recognized.” ( Linné, 1751; see also Mayr, 1969). One might be as justified in using the tuberculation on the chela found here (and in A. whakarakaia ) in all three species named in Araphura plus two of the Araphuroides species; however, this can hardly be a generic character, as it is also present in another and quite distinct tanaellid genus, described below, as well as some species of the unrelated genera Chauliopleona Dojiri & Sieg, 1997 and Akanthophoreus Sieg, 1986 .

The right conclusion is probably to dismiss Araphuroides as a distinct genus, but that must necessitate a reanalysis of all 24 species attributed to these two genera (including those described herein).At present,the three species above attributed to Araphuroides are distinguished simply on their convex (or relatively convex) lateral pereonite margins. On that basis, despite its being apparently close to the Araphuroides species described above, Araphura io is returned to its original genus.