Caenopedina porphyrogigas, Anderson, Owen F., 2009

Anderson, Owen F., 2009, The giant purple pedinid — a new species of Caenopedina (Echinodermata: Echinoidea: Pedinidae) from New Zealand and Australia, Zootaxa 2007, pp. 43-57 : 46-51

publication ID	https://doi.org/ 10.5281/zenodo.185697
DOI	https://doi.org/10.5281/zenodo.6224470
persistent identifier	https://treatment.plazi.org/id/D55D3A62-FFC3-FF8A-FF0E-1DC6FDA0FE2C
treatment provided by	Plazi
scientific name	Caenopedina porphyrogigas
status	sp. nov.

Treatment

Caenopedina porphyrogigas View in CoL sp. nov.

( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Holotype: TD 73 mm; VD 45 mm, Bay of Plenty, North Island, New Zealand (in the vicinity of Waioweka Knoll, a seamount frequently trawled for orange roughy), 37°01.2'S, 176°43.2'E, 976 m, coll. Jim Wills, government fisheries observer aboard FV “Margaret Philippa”, NIWA 25889. Stored in 80% ethanol.

Paratypes: Bay of Plenty: 2 specimens, 37°13.2'S, 177°13.8'E, 693 m, NIWA 6533; 1 specimen, 37°13.2'S, 177°13.8'E, 693 m, NIWA 6534; 1 specimen (69 mm TD), 37°04.8'S, 177°16.2'E, 733 m, NIWA 20775; 1 specimen (102 mm TD), 37°01.2'S, 176°43.2'E, 972 m, NIWA 25894; 2 specimens (92, 92 mm TD), 35°58.2'S, 176°49.2'E, 750 m, NIWA 25895. South Chatham Rise: 2 specimens (34, 45 mm TD), 44°40.8'S, 175°49.2'E, 979 m, NIWA 25886. Stored in 80% ethanol.

Other material: Measurements provided only for intact specimens. Chatham Rise: 3 specimens (57, 62, 53 mm TD), 44°14.4'S, 174°36.6'W, 985 m, NIWA 25878; 1 specimen (34 mm TD), 44°34.8'S, 177° 49.8W, 978 m, NIWA 25881; 1 specimen, 44°43.8'S, 177°13.2'W, 1175 m, NIWA 25885; 10 specimens (43, 46, 49, 54, 57, 58, 78 mm TD), 44°34.8'S, 177°49.8'W, 978 m, NIWA 25888; 6 specimens (32, 40 mm TD), 44°34.8'S, 177°49.8'W, 978 m, NIWA 25892; 1 specimen (69 mm TD), 44°42'S, 178°30'W, 1099 m, NIWA 25893; 2 specimens, 44°45.6'S, 173°37.8'E, Te Papa EC6530. Tasmania/South Tasman Rise: 1 specimen (88 mm TD), 47°27'S, 148°48'E, 884 m, NIWA 25896; 1 specimen, 47°28.2'S, 148°52.8'E, 1031 m, NIWA 25882; 1 specimen, 48°37.8'S, 150°27'E, 913 m, NIWA 25884; 1 specimen, J1 Seamount, 44°14.4'S, 147°21.6'E, 1200 m, CSIRO SS 01/97 40, NMV F165577. West Norfolk Ridge: 1 specimen (84 mm TD), 34°48.6'S, 169°50.4'E, 650 m, NIWA 25883. Louisville Ridge: 3 specimens (82, 72 mm TD), 44°01.2'S, 160°37.2'W, 1000 m, NIWA 25890. Macquarie Ridge: 2 specimens (64, 70 mm TD), 48°31.8'S, 164°57'E, 1060 m, NIWA 39584; 1 specimen, 48°31.8'S, 164°56.4'E, 1364 m, NIWA 39636. All preserved in 80% ethanol. Unknown localities: 6 specimens preserved in 80% ethanol (42, 53, 58 mm TD), NIWA 45980, NIWA 25879, NIWA 25891; 3 cleaned and dried tests (62, 80, 92 mm TD), NIWA 41588.

Etymology: From the Greek porphyro (purple) and gigas (giant) in recognition of the common name in usage for several years, reflecting the colouration and large size of the test.

Diagnosis: Adults large, to at least 100 mm TD; brown spines, length in larger specimens no longer than TD; undifferentiated genital pores, lacking genital grooves; tubercles of apical system numerous and spread uniformly over plates excluding plate margins; areoles of interambulacral plate primary tubercles frequently not confluent; globiferous pedicellariae absent.

Description: Test ( Fig. 1 View FIGURE 1 ) large, circular, flattened slightly, especially aborally; sides slightly unevenly arched with ambitus slightly below vertical mid-line; lower surface slightly concave, upper surface flat. Ratio of VD to TD ranging from 43–77% (n = 15; intact specimens). Colour of cleaned test of holotype and three cleaned and dried tests cream with pink/mauve around sutures, in poriferous zones, and in apical disc. Test of preserved and fresh specimens a distinct purple varying in intensity but strongest around apical disc and on oral side. Primary tubercles perforate and non-crenulate.

Between 27 and 28 plates in interambulacral columns cleaned for examination in holotype, uppermost plate either wholly without a primary tubercle or bearing a semi-formed one and otherwise naked (two of the largest plates bear 1 or 2 small tubercles). Width of interambulacral zone at ambitus 33 mm, individual plates short and wide, distinctly chevron-shaped, pointing downwards ( Fig. 2 View FIGURE 2 ). Each plate bearing large, central tubercle to form vertical series running on slight diagonal from the genital plates to peristome, being more adradial adapically and more interradial adorally; tubercles scarcely diminishing in size from ambitus to apical disc but diminishing considerably in size adorally. Areoles of adjacent tubercles in this series narrowly confluent between some pairs but not others, this condition independent of position in column. Narrow confluence more common in dried specimens, with only a few of the more adapical tubercles non-confluent; variability between individuals apparently not size-related in larger individuals, but examination of a specimen of 40 mm TD showed confluence between all areoles in a series. Second series of much smaller tubercles (less than half the size of those of first series) lying interradially to main series, distinguishable on all but uppermost one or two plates; a third, intermittent series, discernable further interradially, more obvious in central region of column. A series of small tubercles sometimes discernable adradially to main series on dried and cleaned specimens, but not at all obvious on cleaned interambulacral columns of holotype. Remainder of plate surfaces entirely covered in smaller secondary/miliary tubercles and granules, leaving no naked areas. Adorally, buccal notches shallow, gills small and more or less palmate, with spicules comprising large, flat, finely and regularly fenestrated plates.

Ambulacral columns cleaned for examination in holotype comprising 24 plates, uppermost 1 or 2 yet to form into a compound plate. Compound plates almost square, trigeminate in diadematoid style, central plate widening only slightly perradially ( Fig. 2 View FIGURE 2 ). Ambulacral zones much narrower than interambulacral zones—width at ambitus of holotype 9 mm. A large, central primary tubercle placed across the three plates of each compound plate, forming distinct series running from apical disc to peristome. These tubercles, each surrounded by ragged ring of smaller tubercles of various sizes, half size (in surface area) of largest interambulacral tubercles at ambitus (and becoming relatively smaller adapically) but only slightly smaller on lower surface. Apical-most plate of most compound plates below ambitus with secondary tubercle perradial to primary tubercle, distinctly larger than the remainder; remainder of plate surfaces covered in smaller tubercles/granules, as in interambulacrals, leaving no naked areas. Pore-pairs in very shallow arcs of 3, following contour of large primary tubercle to form slightly sinuous vertical line. Pore pairs oblique (perradial pore in each pair lower than adradial pore) and non-conjugate, separated by distinctly raised, oblique wall. Pore-pairs on lower surface (below about the tenth plate) larger and with distinctly raised outer wall, presumably to accommodate larger, more robust tube-feet in this region, arcs more pronounced—forming strong zigzag pattern and widening poriferous zones. Sphaeridia perradial to tube foot of lower element of each compound plate, smooth, oval, about 0.2 mm wide by about 0.3 mm long. Tube-feet spicules a dense meshwork of fenestrated plates in two longitudinal series, typical of genus; with ring of basal plates of more regular rod-like design, with marginal fenestrations ( Fig. 2 View FIGURE 2 ), similar to that of C. alanbakeri (see Rowe 1989: fig. 5).

Apical disc of holotype ( Fig. 2 View FIGURE 2 ) circular to pentagonal (22 mm diameter), relatively large (30% of TD), dark violet colouration extending onto uppermost coronal plates, strongly dicyclic—ocular plates well separated from periproct and about one-fourth size of genital plates. Genital plates approximately equal in size and shape, similar in size to periproct and, excluding naked margins, evenly covered in about 40 small tubercles bearing small spines (up to 5 mm in length) and about 40 small granules bearing mostly triphyllous pedicellariae on long stalks of similar length to the spines. Madreporite conspicuous, pale, moderately raised, wholly confined to and occupying about one-fourth of genital 2 (which is not enlarged), and off centre slightly—towards genital 3. Genital pores circular, located about two-thirds across plate towards interambulacrum, single (with slightly confluent double pore in genital 4 in smaller of two dried specimens). Sexual dimorphism not obvious—of the 20 or so specimens examined, collected at different times and from a variety of localities, none exhibited the slit-like genital pores of males of other species of Caenopedina . Although unlikely, it is possible that all specimens examined were female and males of the species, when examined, will exhibit slit-like genital pores. Genital papillae present, about 3 mm long. Ocular plates identical in size and shape with 8 or 9 larger tubercles bearing spinelets and 6–9 smaller tubercles/granules bearing mostly triphyllous pedicellariae; tubercles/granules mostly confined to plate interior and not extending out beyond ocular pore; ocular pore set in shallow depression near plate edge. Periproct roughly circular, diameter in holotype 9.3 mm, covered in numerous small, flat plates and about 25 larger, swollen plates bearing small tubercles (spines). Anus subcentral, offset slightly toward ocular I in holotype and smaller of the two dried specimens; anus in larger dried specimen offset more towards genital 2 than ocular I.

Many interambulacral primary spines of holotype broken, longest intact spine 33 mm, primary spine diameter 1.4–1.6 mm. Spines cylindrical, tapering only slightly in distal third to blunt point, smooth with no hairs or prominent projections but ornamented with finely serrated longitudinal striations (up to at least 50 in largest spines) formed by distinct terminal wedges of radiating spoke construction ( Fig. 3 View FIGURE 3 ). Central axis filled with fairly dense, irregular meshwork. Milled ring conspicuous, about 30% wider than adjacent spine shaft diameter, but not at all obliquely angled. Secondary spines and ambulacral primaries similar in structure to ambulacral primaries but with somewhat less densely filled axial cavity). Number of longitudinal striations on spines depending on spine diameter—as few as 12 or 13 on minute spines of genital plates to about 30 on the secondary spines of the corona.

Colour of both primary and secondary spines a rich brown, uniform except for distal 5–10 mm of some larger primary spines which are distinctly lighter brown; spine colouration highly constant between individuals, only smallest paratype (34 mm TD) being slightly lighter brown overall.

Ambulacral regions of peristomial membrane embedded with several small plates bearing small spinelets and pedicellariae; buccal plates roughly shield-shaped with pairs close together and distinctly separated from adjacent pairs; tube-feet ringed by small spinelets and pedicellariae.

Low variety of pedicellariae found; a large and small tridentate form, a simple ophicephalous form, and a triphyllous form ( Figure 4 View FIGURE 4 ). Globiferous pedicellariae apparently completely lacking. Large tridentate pedicellariae quite rare on many of the tests examined, although several found adapically on holotype and also thinly distributed over much of the test of one of the Macquarie Ridge specimens. They are of the rostrate form, the long, narrow, serrated blades tapering gradually for about half their length—meeting only in the distal part. Largest found were 5 mm long and, typical for large pedicellariae, lacking a neck. Small tridentate pedicellariae supported by a long neck, more strongly constructed and with a shorter but broader distal section than the larger form, this section varying from about 1.5 to 3 times the length of the proximal part. Ophicephalous pedicellariae very similar to small tridentate pedicellariae and, apart from the basal calcareous arch, differ in that the distal section is generally of similar length to or only slightly longer than the proximal section, and there is no neck. They have a single row of fine marginal teeth and a relatively slight median constriction. Triphyllous pedicellariae typically small (head length typically 150–250 microns) but common over the test and borne on a long neck. In larger examples, the longitudinal septum extends onto the blade a short distance, giving it additional strength.

Occurrence: Since the first specimen was taken in 1984, C. porphyrogigas has been collected from 22 locations, representing 50 individuals. An additional 15 records of this species have been made by fisheries observers and fisheries scientists on New Zealand deep-sea trawlers, without the specimen being kept. These additional records are probably reliable because of the distinctive appearance of this species and its inclusion in photographic identification guides available to observers and researchers since 1997.

Six of the confirmed records (accounting for 25 of the 50 retained specimens) are from the south Chatham Rise ( Fig. 5 View FIGURE 5 ). Of the other confirmed records of C. porphyrogigas , several are associated with seamounts in the Bay of Plenty and West Norfolk Ridge (representing the northern known limit for the species); two records are from the South Tasman Rise (western limit); two from the Macquarie Ridge; one from the Bollons Seamount (southern limit); and one from the Louisville Ridge (eastern limit). Positional data from the unconfirmed records extend the likely species range across the north Chatham Rise, the western Challenger Plateau, and to a seamount feature west of the northern tip of the North Island (Tauroa Knoll).

A conservative but reliable depth range for the species can be determined from the confirmed records where both the start and finish depth were recorded, by taking the shallowest maximum and deepest minimum of these pairs. This gives a range of 350–1200 m with a potential range (taking the shallowest minimum and deepest maximum) of 219–1450 m.